Process control systems and methods using a solid-state additive manufacturing system and continuous feeding systems and structures

Abstract

A process control system and a method for process control of a solid-state additive manufacturing system capable of performing various additive processes, such as joining, additive manufacturing, coating, repair and others, are disclosed. The process control system is capable of simultaneous measuring, monitoring and controlling multiple process variables, viz. material temperature, actuator down force, tool force (or torque), tool position, tool angular and transverse velocity, spindle torque (angular velocity), filler flow rate, filler composition, track width, inert gas flow rate and others. A feeding system for continuous supply of filler material to the solid-state additive manufacturing system is also disclosed. The filler material can be in a form of a powder, granules, briquettes, beads, flakes, wires, rods, films, scrap pieces, sheets, blocks or their combinations. Methods for generation of different periodic and non-periodic structures and joints using the process-controlled solid-state additive manufacturing system are also disclosed.

Claims

1. A system to control addition of a solid filler material to a surface of a workpiece using a solid-state additive manufacturing system, the system comprising: a spindle configured to receive solid filler material; tooling configured to receive the solid filler material from the spindle and add the solid filler material to the surface of the workpiece to provide added solid filler material with a selected microstructure on the surface of the workpiece, wherein the tooling comprises a body and a throat capable of receiving the solid filler material from the spindle, and wherein the spindle is configured to provide a downward force to push the solid filler material through the throat of the tooling during addition of the solid filler material to the surface of the workpiece; and a controller electrically coupled to the spindle and the tooling to control the selected microstructure of the solid filler material added to the surface of the workpiece, wherein the controller is configured to receive a first process variable from the spindle and a second process variable from the tooling, and wherein the controller is configured to independently control the spindle using the received, first process variable and control the tooling using the received, second process variable, to add the solid filler material from the tooling to the surface of the workpiece as plasticly deformed solid filler material, and wherein the controller is configured to use the received, second process variable to control the provided downward force from the spindle.

2. The system of claim 1, wherein the controller is configured to provide the selected microstructure that comprises one or more of a honeycomb structure, a sandwich structure, or a repeating block structure.

3. The system of claim 1, further comprising a solid filler system configured to provide the solid filler material to the spindle, wherein the controller is configured to use a received, third process variable from the solid filler system to control continuous loading of solid filler material into the solid filler system to permit continuous addition of the plasticly deformed solid filler material to the surface of the workpiece.

4. The system of claim 3, wherein the controller is configured to use the received, third process variable to control a down force that pushes the solid filler material toward the spindle.

5. The system of claim 3, wherein the controller is configured to use the received, second process variable to control angular velocity of the tooling during addition of the plasticly deformed solid filler material to the surface of the workpiece.

6. The system of claim 3, wherein the controller is configured to use the received, second process variable to control torque of the tooling during addition of the plasticly deformed solid filler material to the surface of the workpiece.

7. The system of claim 3, wherein the controller is configured to use the received, second process variable and provide closed loop control to control a friction force between the tooling and the surface of the workpiece during addition of the plasticly deformed solid filler material to the surface of the workpiece.

8. The system of claim 3, wherein the controller is configured to use the received, second process variable to control transverse movement of the tooling while the plasticly deformed solid filler material is added to the surface of the workpiece.

9. The system of claim 3, wherein the controller is configured to use the received, second process variable to control layering of the plasticly deformed solid added filler material on the surface of the workpiece.

10. The system of claim 3, wherein the controller is configured to use the received, second process variable to control the temperature of the surface of the workpiece.

11. The system of claim 3, wherein the controller is configured to use the received, third process variable to control a temperature of solid filler material in the solid filler system.

12. The system of claim 1, wherein the controller is configured to monitor thickness and width of the solid filler material added to the surface of the workpiece, and wherein when the thickness and width of the added solid filler material is achieved, the controller is configured to retract the tooling from the surface of the workpiece to discontinue addition of the solid filler material to the surface of the workpiece.

13. The system of claim 1, further comprising a first sensor configured to measure the first process variable, and a second sensor configured to measure the second process variable, wherein the first sensor and the second sensor are each electrically coupled to the controller.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The accompanying drawings illustrate certain aspects of embodiments of the present invention and should not be used to limit the invention. Together with the written description the drawings serve to explain certain principles of the invention.

(2) FIG. 1 is a block diagram of a complex process control system for a solid-state additive manufacturing system comprising multiple open and closed control loops according to an embodiment of the invention.

(3) FIG. 2 is a block diagram of a closed-loop control system for the solid-state additive manufacturing process with a variable set point (SP) and a variable process value (PV) as a feedback according to an embodiment of the invention.

(4) FIG. 3A is a block diagram of a feedback control system for the actuator down force variable in the additive manufacturing process according to an embodiment of the invention.

(5) FIG. 3B is a flow diagram of the process control of actuator down force and filler flow rate in an additive manufacturing process according to an embodiment of the invention.

(6) FIG. 3C is a flow diagram of the process control of the friction force and workpiece surface temperature in a solid-state additive manufacturing process according to an embodiment of the invention.

(7) FIG. 4 is a block diagram of a feedback control system for the spindle torque variable in the solid-state additive manufacturing process according to an embodiment of the invention.

(8) FIG. 5 is a block diagram of a feedback control system for the tool angular velocity variable in the solid-state additive manufacturing process according to an embodiment of the invention.

(9) FIG. 6 is a block diagram of a feedback control system for the feeder temperature variable in the solid-state additive manufacturing process according to an embodiment of the invention.

(10) FIG. 7 is a block diagram of a feedback control system for the tool temperature variable in the solid-state additive manufacturing process according to an embodiment of the invention.

(11) FIG. 8 is a block diagram of a feedback control system for the tool temperature variable in the solid-state additive manufacturing process according to an embodiment of the invention.

(12) FIG. 9A is a graph showing upper and lower limits which are imposed for monitoring variables that are not controlled in a closed-loop control system, but which might be critical for the solid-state additive manufacturing process under certain circumstances. The process control system is capable of imposing known strategies to bring the variable value within the limits when it is outside the range.

(13) FIG. 9B is a graph of torque changes with time during deposition of multiple layers of Aluminum. Results of a software-controlled solid-state deposition process are presented when the torque is controlled and maintained to be constant during the layer deposition.

(14) FIG. 9C is a graph of torque changes with time during deposition of multiple layers of Aluminum. Results of a software-controlled solid-state deposition process are presented when the spindle speed is controlled and maintained to be constant during the layer deposition.

(15) FIG. 9D is a torque map (in the x-z plane) during deposition of multiple layers of Aluminum (layers are being deposited on top of each other by tool's forward-backward translational movements), where the torque is controlled during the deposition.

(16) FIG. 9E is a torque map (in the x-z plane) during deposition of multiple layers of Aluminum (layers are being deposited on top of each other by tool's forward-backward translational movements), where the spindle speed is controlled during the deposition.

(17) FIG. 9F is a graphical presentation showing a reduction in spindle speed leading to an increase in the spindle torque.

(18) FIG. 9G is a graphical presentation showing an increase in actuator velocity leading to an increase in the actuator force.

(19) FIG. 10 is a block diagram of a computer-controlled solid-state additive manufacturing system for executing different additive manufacturing operations and monitoring and controlling their process variables according to an embodiment of the invention.

(20) FIGS. 11A, 11B, 11C and 11D are schematic diagrams showing a code-controlled solid-state additive manufacturing process of generating 3D structures (FIG. 11A) and generated triangular, square and hexagonal honeycomb structures (FIGS. 11B-D) according to embodiments of the invention.

(21) FIG. 12A is a schematic diagram of dual super-imposed hexagonal honeycomb structures on a single substrate generated by a computer-controlled solid-state additive manufacturing process according to an embodiment of the invention.

(22) FIG. 12B is a schematic diagram of hierarchical hexagonal honeycomb structures built-up on a single substrate generated by a computer-controlled solid-state additive manufacturing process according to an embodiment of the invention.

(23) FIGS. 13A and 13B are schematic diagrams of dual super-imposed honeycomb structures where the structures have the same cell heights (FIG. 13A) and different cell heights (FIG. 13B) according to embodiments of the invention. The cell wall thickness can be the same or different for the two honeycomb structures.

(24) FIG. 14A is a schematic diagram of a laminate structure built-up by depositing a honeycomb structure on each substrate according to an embodiment of the invention. Each subsequent honeycomb structure may overlap the honeycomb structure underneath or may be displaced with regard to the underlying honeycomb structure. The substrate material and the honeycomb structure material can differ from each other or can be the same. Also, each subsequent substrate/honeycomb structure can be made of the same material or a different material from the previous layer. No adhesive layers are used between the honeycomb layer and the substrates.

(25) FIG. 14B is a schematic diagram of a multi-layer structure comprising multiple honeycomb structures on different substrates according to an embodiment of the invention. The first substrate with double inter-imposed hexagonal honeycomb structures is covered with a second substrate over which the second honeycomb structure, overlapping the larger honeycomb structure on the underlying substrate, is deposited. The second honeycomb structure can also be displaced with regard to the underlying honeycomb structure. Additional substrates can be added with build-up honeycomb structures on their surface yielding multi-layer honeycomb structures.

(26) FIG. 14C is a schematic diagram of a sandwich structure built-up by depositing a honeycomb structure between two substrates according to an embodiment of the invention. The substrate material and the honeycomb structure material can differ from each other or can be the same. No adhesive layers are used between the honeycomb layer and the substrates. Stacks of multiple sandwiched structures are possible as well.

(27) FIG. 15A is a schematic diagram of a hexagonal honeycomb structure made of material A with individual cells filled with material B generated by a computer-controlled solid-state additive manufacturing process according to an embodiment of the invention.

(28) FIG. 15B is a schematic presentation of generated honeycomb structures additionally reinforced with stiffening ribs all generated by a computer-controlled solid-state additive manufacturing process according to an embodiment of the invention.

(29) FIG. 16A is a schematic diagram showing the mixing of two materials A and B with a code-controlled system according to an embodiment of the invention.

(30) FIG. 16B is a schematic diagram showing a deposited layer with a well-controlled material A/B ratio according to an embodiment of the invention.

(31) FIGS. 16C and 16D are schematic diagrams of a filler material in a form of a hollow bar (or rod) made of material A filled with material B according to an embodiment of the invention.

(32) FIG. 16E is a schematic diagram of a filler material in a form of a hollow bar (or rod) made of material A and filled with flakes of material B according to an embodiment of the invention.

(33) FIGS. 16F and 16G are schematic diagrams of a concentration gradient along the deposition length (FIG. 16F) and along the layer thickness (FIG. 16G) generated by a code-controlled solid-state additive manufacturing system according to embodiments of the invention.

(34) FIGS. 17A, 17B, 17C and 17D are schematic diagrams of a process of joining two parts, made of the same, similar or dissimilar materials according to embodiments of the invention, where FIG. 17A shows the solid-state additive manufacturing machine is depositing reinforced or unreinforced material that provides a good bonding between the parts needed to be joined, FIG. 17B shows two parts joined together; and FIGS. 17C and D show additional strengthening/stiffening structures are added for the bonding zone after removal of the backing plate.

(35) FIGS. 18A, 18B and 18C are schematic diagrams showing a process of joining two parts made of same, similar or dissimilar materials according to embodiments of the invention, where FIG. 18A shows the additive manufacturing machine is depositing reinforced or unreinforced material that would keep the two parts in place, and FIGS. 18B and C show two parts joined together with stiffening structures.

(36) FIGS. 19A, 19B, 19C and 19D are schematic diagrams of a process of joining two parts made of same, similar or dissimilar materials according to embodiments of the invention, where FIG. 19A shows the additive manufacturing machine is depositing reinforced or unreinforced material that would provide a good bonding between the parts needed to be joined, FIG. 19B shows two parts joined together, and FIGS. 19C and D show additional strengthening/stiffening structures added to the bonding zone.

(37) FIGS. 20A, 20B 20C, 20D and 20E are schematic diagrams of a process of joining two parts made of same, similar or dissimilar materials according to embodiments of the invention, where FIG. 20A shows the solid-state additive manufacturing machine is depositing reinforced or unreinforced material that would keep the two parts in place and FIGS. 20B-E show embodiments of two parts joined together with stiffening structures.

(38) FIGS. 21A and B are schematic diagrams of a process of joining two parts made of same, similar or dissimilar materials according to embodiments of the invention, where FIG. 21A shows the additive manufacturing machine is depositing reinforced or unreinforced material that would keep the two parts in place, and FIG. 21B shows two parts joined together with stiffening structures.

(39) FIGS. 22A, 22B and 22C are schematic diagrams of a process of making sandwiched thermoplastic polymer structures comprising a prepreg inter-layer according to embodiments of the invention, where FIG. 22A shows deposition of the first thermoplastic polymer layer, FIG. 22B shows placement of the pre-manufactured prepreg, and FIG. 22C shows deposition of the second thermoplastic polymer layer.

(40) FIGS. 23A, 23B, 23C and 23D are schematic diagrams of a process of making sandwiched metal structures comprising a prepreg inter-layer according to embodiments of the invention, where FIG. 23A shows deposition of the first metal, metal alloy or MMC layer, FIG. 23B shows placement of the pre-manufactured prepreg layer, FIG. 23C shows deposition of the second metal, metal alloy or MMC layer, and FIG. 23D shows deposition of thermoplastic layers around the prepreg inter-layer for providing better bonding.

(41) FIG. 24A is a schematic diagram of a solid-state additive process of repairing a blind hole and a variety of surface cracks/defects according to an embodiment of the invention.

(42) FIG. 24B is a schematic diagram of a process of repairing holes and cracks/defects using a backing plate according to an embodiment of the invention.

(43) FIGS. 25A and 25B are schematic diagrams of a drive wheel system for a continuous supply of rod-like filler material to a solid-state additive manufacturing machine according to embodiments, where FIG. 25A shows a drive wheel system with one set of rollers and FIG. 25B shows a drive wheel system with three sets of rollers.

(44) FIGS. 25C, 25D and 25E are schematic diagrams of a drive wheel system for continuous supply of rod-like filler material to a solid-state additive manufacturing machine according to embodiments, where FIG. 25C shows a drive wheel system with multiple sets of rollers, where the rollers can have specific roller surface features or textures, and FIGS. 25D and 25E show a drive wheel system with multiple sets of rollers with variable gaps between the rollers.

(45) FIG. 25F shows a set of rollers where the gap between them is defined by springs.

(46) FIG. 25G is a schematic diagram of a drive wheel system for continuous supply of rod-like filler material to a solid-state additive manufacturing machine according to an embodiment. The drive wheel system shown has a set of rollers presented to re-track (pull-away) the filler rod from the workpiece surface.

(47) FIGS. 26A-26E are schematic diagrams showing cross-sectional views of different types of feeding rollers according to embodiments.

(48) FIG. 27A is a schematic diagram showing feeding rollers with crescent blades (or knife-type blades) for chopping pieces from a block of filler material according to an embodiment.

(49) FIG. 27B is a schematic of feeding rollers with paddle-type blades for supplying briquettes, chops, flakes, granules or powder into the solid-state additive manufacturing system.

(50) FIG. 27C is a schematic showing metal cans that can be introduced in the feeding system of the solid-state additive manufacturing system and used as filler material.

(51) FIG. 27D is a schematic showing plastic bottles that can be introduced in the feeding system of the solid-state additive manufacturing system and used as filler material.

(52) FIGS. 28A, 28B and 28C are schematic diagrams showing filler material rods with different cross-sections according to embodiments.

(53) FIG. 28D is a schematic diagram showing feeding rollers with a groove (channel) for stabilizing the rod supply to the solid-state additive manufacturing machine according to an embodiment.

(54) FIG. 28E is a schematic diagram showing feeding rollers with multiple groves for supplying multiple filler rods to the solid-state additive manufacturing machine according to an embodiment. The rods can be made of different materials enabling in situ formation of MMC, alloy, blends and composites before the filler material reaches the workpiece.

(55) FIG. 28F is a schematic diagram of a drive wheel system for continuous supply of fillers in the form of plates, sheets and/or films according to an embodiment.

(56) FIG. 28G is a schematic diagram of a drive wheel system for continuous supply of sheets made of different materials and in situ formation of MMC, blends, alloy and/or composites according to an embodiment.

(57) FIGS. 29A and 29B are schematic diagrams of several feeding systems with auger screws for delivering powder, beads, flakes and/or granular filler material, where FIG. 29A shows an auger screw in the hopper according to an embodiment and FIG. 29B shows an auger screw in the spindle according to an embodiment. In embodiments, the system can have one or more auger screws in both the hopper and the spindle.

(58) FIG. 29C is a schematic diagram showing an auger screw extending from the hopper via the spindle into the hollow tool according to an embodiment.

(59) FIGS. 30A, 30B, 30C, 30D, 30E, 30F, 30G and 30H are schematic diagrams showing various auger screw designs used for continuous supply of powder and/or granular filler material according to embodiments.

DETAILED DESCRIPTION

(60) Reference will now be made in detail to various exemplary embodiments of the invention. It is to be understood that the following discussion of exemplary embodiments is not intended as a limitation on the invention. Rather, the following discussion is provided to give the reader a more detailed understanding of certain aspects and features of the invention.

(61) Embodiments of the present invention provide novel and nonobvious improvements upon previous technology related to filler material feeding systems for solid-state additive manufacturing. Such previous technology is described in U.S. Patent Application Publication No. 2014/0174344, which is individually incorporated by reference herein in its entirety to provide an efficient way of supplementing the enabling disclosure of this invention. The present invention is also related to the disclosures provided in U.S. Pat. No. 8,893,954 (see also 2014/0134325), U.S. Pat. No. 8,636,194 (see also 2010/0285207), U.S. Pat. No. 9,643,279 (see also 2016/0107262, U.S. Pat. No. 9,943,929 (see also 2017/0216962), U.S. Pat. No. 9,205,578 (see also 2014/0130736), U.S. Pat. No. 8,632,850 (see also 2012/0009339), U.S. Pat. No. 8,875,976 (see also 2012/0279441), U.S. Pat. No. 8,397,974 (see also 2012/0279442), U.S. Pat. No. 9,862,054 (see also 2016/0074958), U.S. Pat. No. 9,266,191 (see also 2015/0165546), U.S. Pat. No. 9,511,446 (see also 2016/0175982), U.S. Pat. No. 9,511,445 (see also 2016/0175981), and U.S. Application Publication Nos. 2008/0041921, 2013/014012, 2017/0043429, 2017/0057204, 2018/0085849, as well as International Patent Application Publication No. WO2013/002869, which are each incorporated by reference herein in their entireties.

(62) As used herein (within both the specification and the drawings), the term “code” refers to what is known in the art as computer-readable code, computer-readable instructions, computer-executable instructions, or “software”. Any of the algorithms, methods, processes, flow diagrams, and/or routines, described in this specification or depicted in the drawings can be programmed or implemented in such code. The computer-readable instructions can be programmed in any suitable programming language, including JavaScript, C, C#, C++, Java, Python, Perl, Ruby, Swift, Visual Basic, and Objective C. By such programming the computer-readable instructions, code, or software instruct a processor to carry out the operations and commands of the novel process control system and method described herein.

(63) A skilled artisan will further appreciate, in light of this disclosure, how the invention can be implemented, in addition to software, using hardware or firmware. For example, the hardware can be or include circuitry for performing a specific operation, process, command, method, algorithm, or other task described in this disclosure. As such, the process control system and method disclosed herein can be implemented in a system comprising any combination of software, hardware, or firmware.

(64) As used herein, the term “coating material” is used interchangeably with “filler material”; both relate to an additive material which is fed through a throat of a rotating stirring tool as described in this disclosure. The additive material can also be referred to interchangeably in this disclosure as a “consumable” material.

(65) As used herein, the term “honeycomb” or “honeycomb structure” refers to a manmade three-dimensional structure having rows of identically-shaped and identically-sized cells juxtaposed or adjacent to each other. The cells can be any rectilinear shape including triangular, square, rectangular, hexagonal, octagonal, and so on. The cells can also be superimposed, have one or more additional layers which can have geometries that differ from one layer to another. Thus, such structure can resemble natural honeycomb with strictly hexagonal cells or can have different rectilinear variations such as the examples shown in the drawings.

(66) In embodiments, the present invention provides: (a) a novel process control system for a solid-state additive manufacturing system and associated additive manufacturing processes performed with the solid-state additive manufacturing system, (b) a process control method for executing and controlling different processes with the manufacturing system, (c) various additive structures that can be generated with the software-controlled manufacturing system, and (d) various feeding system designs for continuous supply of the filler material to the solid-state additive manufacturing machine.

(67) In embodiments, the software-controlled solid-state additive manufacturing system includes the solid-state additive manufacturing machine with numerous associated parts and tools (such as various tools with the same or different tool shapes for processing different material types, including for example, polymer fillers, metal fillers, blends, composites, and parts such as clamps, spindle, bearings for the spindle, motors, generator, drives, inert gas supply, shield, machine covers, etc.), as well as multiple control-, sensor-, monitoring-, and/or imaging-devices, driving units, motors, and actuators. A synchronized and successful operation of the solid-state additive manufacturing system is possible by engaging a reliable process control system configuration that is capable of controlling the process variables and the movements of the machine parts during the particular solid-state additive manufacturing process. The process control system includes a software-operated solid-state additive manufacturing machine and numerous detectors, cameras, gauges, actuators (controllers) located at single or multiple locations within the solid-state additive manufacturing system for control and execution of the particular operations and routines of a given solid-state additive manufacturing process, where the process can be joining, coating, repair, surface functionalization or 3D additive structure fabricated with the software-controlled solid-state additive manufacturing system.

(68) In one embodiment, multiple operations and/or routines are needed to execute the given solid-state additive manufacturing process, e.g. coating. The process control system is capable of controlling all or some of the process steps and associated operations, which include one or more of or any combination or sub-combination of the following (not listed in particular order, some of these steps and operations occur at the same time or occur in a different order than listed): load the filler material (powder, granules, rod), provide the sufficient down force (depending on the filler type) that would push the filler down towards the spindle, achieve desired spindle angular velocity and torque, achieve desired tool angular velocity and torque, achieve desired filler material temperature, provide workpiece clamping, achieve desired workpiece temperature, proceed with an inert gas purge into the working area, bring the rotating tool into close proximity with the workpiece, proceed with fixed spot stirring and filler deposition, proceed with transverse tool movement while the filler is still depositing, proceed subsequent build-up of layers via the tool's back-forth transverse movement to achieve the desired deposited layer (coating) thickness, perform lateral tool movement and tool back-forth movement to achieve the desired deposited layer (coating) width, once the deposited layer thickness and width are achieved, reduce the spindle and tool angular velocity and torque to zero, and retract the tool from the workpiece.

(69) Furthermore, embodiments provide a method for process control of a solid-state additive manufacturing system. In one embodiment, the method for a process-controlled solid-state additive manufacturing system includes at least one of or any combination or sub-combination of the following steps: Identifying measured, controlled and manipulated process variables for a particular solid-state additive manufacturing process; Identifying the independent and dependent process variables for a given solid-state additive manufacturing process; Selecting a process control strategy and a process control design structure; Identifying the critical points in the solid-state additive manufacturing system, where the given process variables must be monitored and/or measured; Determining the continuity of each variable measurement; and in case of discontinuous measurements, determining the frequency of taking each variable measurement; Generating algorithms for process control of the variables that need to be controlled and manipulated during the solid-state additive manufacturing process; Generating computer-readable code for the controllable and manipulated process variables; Generating computer-readable code for controlled movements of different machine parts relevant for a given process; Programming a computer using the generated computer-readable code for controlling the process variables and controlling the machine parts, relevant for the execution of a given solid-state additive manufacturing process, Generating desired set points, “SP”, for each of the controlled process variables in the given process; Measuring and recording the process values, “PV”, for each of the controlled process variable at critical locations in the solid-state additive manufacturing system and at certain time periods for discontinuous variable measurements; Identifying the critical ranges for the difference Δ, where Δ is calculated as: Δ=SP−PV for each of the controlled process variables; in situations where the Δ-value is within the critical range, and there is thus no need for correction of the particular variable; Calculating the difference Δ (Δ=SP−PV) for each of the controlled process variable; Generating feedback control signals for each of the controlled process variables by computer execution of the computer-readable codes that control the process variables; Correcting the controlled process variable, if the difference (Δ) is outside of the critical range for a given process variable; Generating movements of the relevant solid-state additive manufacturing machine parts by computer execution of the computer-readable codes that control the operation of the solid-state additive manufacturing machine parts.

(70) A variety of predefined additive structures can be generated with the software-controlled solid-state additive manufacturing system as such system is capable of a solid-state thermo-mechanical additive (e.g. layer-by-layer) manufacturing process. Some of the additive structures, periodic and non-periodic structures, super-imposed and hierarchical structures are described in the embodiments below.

(71) The solid-state additive manufacturing process and manufacturing system are affected by many input process variables, designated as A, B, . . . N, . . . X, Y, Z in FIG. 1 and many process disturbances. As shown in FIG. 1, selected process variables, depending on their relevance for the particular solid-state additive manufacturing process, can be controlled in closed-loops. In such cases, the variables' process values are provided as feedback into the process and enter the process as “manipulated variables” (FIG. 1). The Filter in the closed loop process control determines if the variable needs a correction, while the Controller takes an action when the variable is off from the predetermined range and needs correction by adjusting one or more input variables which enter and influence the process. The closed-loop control cycle is then reinitiated by Feedback received from one or more sensors, gauges, or detectors which measure corresponding output variables exiting the process. Additionally, one or more disturbances may enter the process which may affect the value of the one or more output variables. Not all of the monitored and measured variables (e.g. X-, Y-, and Z-variables) are controlled with a closed loop control system. For instance, the N-variable in FIG. 1 is measured or monitored, but not closed-loop controlled. However, in some embodiments, if the N-variable value goes out of range, then actions can be taken through some of the other variables that are controlled via closed-loop process control systems and are closely related to the N-variable, or the operator can manually intervene in the process. The variables A and B in FIG. 1 are not monitored or measured during the solid-state additive manufacturing process.

(72) FIG. 2 presents a block diagram of a closed-loop variable control process for a single generic machine variable, where the variable process value (PV) information is continuously fed into the system and compared to the desired variable values (set point, SP), and consequently, manipulated by the Controller in cases when the Filter determines that the difference Δ is out of the critical range. Again, output from the system is measured by one or more sensors, detectors, and cameras, and this output can be affected by one or more process disturbances. Specific examples of control processes for closed-loop controlled variables are provided in FIG. 3A and FIGS. 4-8, which are related to block diagrams for the actuator down force, spindle torque, tool angular velocity, feeder temperature, tool temperature, and traverse speed closed-loop control processes, respectively.

(73) In some embodiments, the actuator down force is controlled in a closed control loop, and consequently, the filler material flow rate (i.e. filler material supply to the workpiece) is controlled, as well. This is a unique feature of the process control system of the present invention and distinguishes the process control system from process control systems where no filler material is added to the welding process. A flow diagram of the process control of the actuator down force, F.sub.act and the filler flow rate, Q.sub.f is provided in FIG. 3B. Initial information on one or more parameters of the filler material, its nature, viz. metal, metal alloy, MMC, polymer, ceramic, or composite, and the filler form, viz. powder, granules, or rods, are provided as inputs for the computer control code for the material; one or more spindle and tool parameters, such as spindle and tool torque and angular velocity, spindle and tool temperature and others, which can be employed during a given solid-state additive manufacturing process, are also fed into respective computer control codes as inputs. The actuator push down force, F.sub.act, is controlled in a closed loop system, which control system might also involve the dependent variable, filler flow rate, Q.sub.f. The boundary conditions for both variables are then imposed as the maximum and the minimum acceptable values for F.sub.act (i.e. F.sub.act,max and F.sub.act,min) and Q.sub.f. (i.e. Q.sub.f,max and Q.sub.f,min) If the F.sub.act is outside the acceptable range defined between the maximum and minimum F.sub.act value, F.sub.act,max and F.sub.act,min, then an alarm message “F.sub.act out of range” appears on a computer monitor used for the software control of the solid-state additive manufacturing system. In such cases, the computer code responsible for controlling the actuator down force activates the power supply to add or reduce the power depending on the measured F.sub.act (i.e. if it is below F.sub.act,min or if it is above the F.sub.act,max value, respectively). If the F.sub.act value is within the acceptable range defined between F.sub.act,min and F.sub.act,max, then the code checks the filler material flow rate Q.sub.f, which is mainly affected by the actuator push down force, F.sub.act, but can be affected by other process parameters, such as spindle temperature and torque. If the Q.sub.f is outside the range defined between Q.sub.f,min and Q.sub.f,max, then an alarm message “Q.sub.f out of range” appears on the computer monitor and an action is taken via adding or reducing the power supply, which directly affects the actuator down force F.sub.act, and thus, the filler flow rate, Q.sub.f. The actuator down force F.sub.act, and the filler flow rate Q.sub.f are recorded, and then a decision is made to stop or reinitiate the control process.

(74) In another embodiment, the friction force, F.sub.f between the tool shoulder and the workpiece surface is controlled in a closed loop control system. Since this friction force directly affects the heat generated by the friction, which usually occurs in the affected working zone including the workpiece surface, then the workpiece surface temperate, T.sub.f would also be directly affected by the friction force, F.sub.f. The friction force, F.sub.f is controlled in a closed loop process control system as presented in FIG. 3C. Input parameters, such as the actuator down force, F.sub.act and filler material flow rate, Q.sub.f, as well as the spindle and tool parameter are fed into the computer software/code embodying the algorithms governing the solid-state additive manufacturing process. The boundary conditions for the Ff (i.e. Ff, max and Ff, mm) and Tf (i.e. Tf, max and T.sub.f,min) are imposed. Once the process starts, F.sub.f is closely recorded. If it is within the range defined between F.sub.f,min and F.sub.f,max, then the code continues to record the T.sub.f on the workpiece surface, which is mainly affected by the friction force, F.sub.f, but can be also affected by other parameters, as well. If the F.sub.f is outside the defined range, then an alarm message “F.sub.f out of range” appears on a computer monitor and actions are taken by increasing or reducing the actuator push force and/or spindle torque, depending of the actual F.sub.f value (i.e. if it is below or above the acceptable range for F.sub.f). Consequently, the workpiece surface temperature, T.sub.f which is mainly affected by the friction can be controlled, as well. The friction force, F.sub.f, and the workpiece surface temperature, T.sub.f are recorded, and then a decision is made to stop or reinitiate the control process.

(75) In yet another embodiment, the friction coefficient is controlled in a closed loop based on a flow diagram very similar to the flow diagram for the friction force, F.sub.f control presented in FIG. 3C.

(76) In another embodiment, the disclosed process control system for a solid-state additive manufacturing machine is capable of executing one or more known strategies for dealing with a monitored process variable in an open-loop control system, when it is outside of the desired range (FIG. 9A).

(77) In one embodiment, as an example only, the torque applied to the deposited material can be controlled and maintained constant or kept within a narrow range during each layer deposition (FIG. 9B). Multiple layers can be deposited on top of each other by tool forward-backward translational movements. Except for the beginning of the solid-state deposition process, the torque in each layer of deposited material (aluminum in this case), which are deposited on top of each other by forward-backward deposition, is maintained constant via adjusting the spindle speed which itself is controlled by adjusting the driving current to the spindle.

(78) In another embodiment, during deposition of multiple layers (of aluminum) on top of each other by tool forward-backward translational movements, the spindle speed is kept constant during each layer deposition. In this case, the torque applied to the deposited material varies during the deposition of the layers (FIG. 9C).

(79) In a different example, the torque is maintained constant (or varies in a narrow range) during multi-layer deposition. The torque map shown in FIG. 9D in such a torque-controlled solid-state additive manufacturing process shows the narrow range of torque values achieved during multiple layer deposition. In contrast, in a no-torque-controlled process for a multi-layer deposition process, where the spindle speed is kept constant, torque variations during a single layer deposition, as well as variations across different layers are expected (FIG. 9E). Due to the difference in the torque values between a torque-controlled process and a no-torque controlled solid-state additive manufacturing process, the resulting microstructures in the deposited layers are different because of the different material temperatures achieved during the deposition, which temperatures are directly related to the applied torque.

(80) Process independent and dependent variables can be controlled. Control is useful for influencing material properties and deposition rate of deposited material. Properties such as surface roughness, mechanical properties, wear resistance, fatigue resistance, etc. can be modified for a given material by varying or holding constant one or more process variables. In FIG. 9B the control system is holding torque at a constant level across the length of each layer and from layer to layer. The control system adjusts other parameters to create torque stability. Other parameters that may be adjusted include rotational speed of the tool, filler feed rate, traverse rate, temperature of added material, temperature of substrate, ambient temperature, etc.

(81) It can be seen in FIG. 9C that without choosing torque as the parameter to hold constant, it will not be constant. In FIG. 9C, the spindle speed (rotational speed of the tool) is held constant. As a result, the torque required for successful operation over many layers decreases. Both of these figures show data for a multilayer deposit and sharp decreases in torque indicate where the tool is being moved upward in the vertical axis to begin a new layer.

(82) FIG. 9D shows process data for Torque control where the control system is instructed to maintain a torque value across layer lengths. This data shows the ability for the control system to successfully maintain a value, similar to FIG. 9B.

(83) FIG. 9E shows the impact on Torque if it is not selected for control. Similar to FIG. C, this shows that choosing spindle speed as the variable to hold constant will create a fluctuation in torque.

(84) Hypothetically, the impact of change in control variables can result in following for a 6xxx series aluminum alloy:

(85) TABLE-US-00002 Variable/ Range of Control Parameter Values Value Impact Relationship Spindle 100-600 RPM 500 Increased Influences speed wear torque resistance, increased UTS Translation .5-30 IPM 21 IPM Reduced Increases rate surface with finish Increased roughness feed rate Feed rate 1-25 IPM 20 IPM Increased Increases fatigue with resistance increased translation rate Ambient 45-300 F. 70 F. Decrease Influences temperature residual torque stress Torque 60-100 ft-lb 90 ft-lb Increased Decreases YS with increased spindle speed Build Increased Decreases temperature UTS, YS, with ductility increased temperature Layer 0.01-0.06″ 0.04″ Process Influences height efficiency torque Track 0.35-2.10″ 1.70″ Process Influences width efficiency torque Temperature 0-400 F. 200 F. Increased Influences control UTS torque Track 0-100% 25% Full Influences overlap density torque

(86) The control system allows for automated quality control due to the repeatability and predictability of process variables to outcomes. Trials indicate that changes in the variables in the chart impact the properties and condition of the deposited material.

(87) TABLE-US-00003 Trial Yield Stress (MPa) U.T.S. (MPa) Elongation % 1 74.3 133 24% 2 72.9 137.2 23% 3 73 137.5 22% 4 76.1 134.7 23% 5 77.9 136.3 24% 6 76 130.8 22% 7 77 120.4 11% 8 77.5 135.9 17% 9 73.6 133 25% 10 77.2 131.2 17% 11 77.3 127.3 14%

(88) FIG. 9F is a graphical presentation of the reduction in spindle speed leading to an increase in the spindle torque.

(89) FIG. 9G is a graphical presentation of the increase in actuator velocity leading to an increase in the actuator force.

(90) In some embodiments, process control algorithms are based on the flow diagrams created for each controllable process variable. Two of the many flow diagrams constructed for the process control system are provided in FIGS. 3B and 3C.

(91) In some embodiments, the algorithms are transformed into computer-readable code and are compiled into executable software that is capable of imposing different control strategies for each of the controlled process variables in a particular solid-state additive manufacturing process (FIG. 10). The software including multiple computer-readable codes which take into account various material properties, process parameters, etc. As an example only, the filler material properties (e.g melting point Tm, friction coefficient, compressive strength), the filler form (e.g. powder, granules, rod, flakes, sheets), the workpiece material properties (e.g. Tm, strength, friction coefficient), the workpiece shape and size, the tool material strength and shape, and the desired track thickness and track width are taken into account in the software-controlled system to calculate the required angular velocity of the spindle and that of the tool (if different), the traverse velocity of the tool relative to the workpiece, the number of tool passes over the workpiece surface and the down force required to execute a given solid-state additive manufacturing process. The software-controlled system further receives input from one or more sensors, cameras, and measurement devices, and affects one or more process variable by providing output to various drives controlling machine components such as actuators, the tool, the spindle, x,y,z motion controllers, the workpiece, the filer, and the clamping system.

(92) Furthermore, in some embodiments, each computer-readable code is written in a such way that it can be easily combined with other code to generate an executable software specific for a given process; for instance, software for joining, software for coating, software for repair, etc.

(93) In some embodiments, the solid-state additive manufacturing software allows for the machine operator to change the process variable process value manually, if needed. For example, the variable process values can be presented on a screen or other computer display in real-time, and the software can allow the operator to manually enter the variable process value, manipulate various machine tools associated with a particular process variable, and so on.

(94) In another embodiment, in the case of certain filler material types, such as metals, MMCs and metal alloys, an algorithm or code predicts the process variables' SP that can yield a given micro-structure(s) in the deposited layer; very often, refined grain structures compared to the incoming material grain structures are desirable when dealing with these materials in the solid-state additive manufacturing process.

(95) In another embodiment, the code that controls the tool rotation is in close interaction with the code controlling the spindle rotation, and these two parts, the spindle and the tool, can rotate with the same or different angular velocities, but need to be well-synchronized for a successful process execution.

(96) In another embodiment, a code is used to control the temperature of the spindle, which is dependent on the spindle torque, which in turn is dependent on the spindle angular velocity. The process control system includes a closed control loop of the spindle angular velocity, while the spindle temperature is treated as a nested variable dependent on the spindle angular velocity and spindle torque.

(97) In yet another embodiment, a code is used in the process control system that regulates the filler material temperature. This code is dependent on the code for regulating the feeder temperature, spindle temperature and tool temperature, the latter two variables being dependent on the corresponding angular velocities and torques of the spindle and the tool.

(98) In other embodiments, the process-controlled solid-state additive manufacturing system is capable of fabricating complex contour parts and structures, periodic and non-periodic structures, viz. honeycomb structures, hierarchical structures, super-imposed structures, gradient structures and other structures using a platform capable of multi-axis motion.

(99) In one embodiment, the code controls the density and/or porosity of the deposited material by controlling the filler material flow rate and the inert gas flow rate that is blown during the deposition process.

(100) In one embodiment, the computer-controlled solid-state additive manufacturing machine is capable of generating periodic cell structures, such as honeycomb structures. Honeycomb structures in a sandwiched geometry have been known to be superior to many other cellular structures as such structures offer a light-weight structure for various load-bearing and energy-absorbing applications. However, most of the traditional processes for making sandwiched structures with honeycomb cores involve multiple steps, and most of the times, require application of adhesive layers to adhere the honeycomb core to the outer sheets of the sandwiched structure. Embodiments of the solid-state additive manufacturing processes and systems of the invention are capable of manufacturing complex honeycomb structures without an adhesive layer.

(101) A variety of honeycomb structures for enhanced mechanical and particularly compressive performance which still provide an excellent strength-to-weight ratio are possible with the computer-controlled solid-state additive manufacturing system. Furthermore, the computer-controlled solid-state additive manufacturing machine is capable of building up any complex cell structures involving cell sub-structures for tailored mechanical performance in any direction (in x, y or z-direction) or tailored isotropic mechanical performance.

(102) In one embodiment, the computer-controlled solid-state additive manufacturing process governs the predetermined x-y movements of the tool relative to the surface of the workpiece while building the non-periodic or periodic, e.g. honeycomb structure in addition to governing the rotational movement of the tool (FIG. 11A). The software-controlled solid-state additive manufacturing system is capable of building the cell structure with any material of choice, e.g. metal, MMC, metal alloy, plastic, ceramic, polymer, composite material comprising reinforcing fibers or particles, etc. The additive material (i.e. the filler material) 1101 passes through the hollow rotating tool 1102 on the substrate (or backing plate) 1103. Depending on both the tool rotational and translational movements, a deposit 1104 with particular track width and thickness is formed on the substrate or backing plate 1103.

(103) In some embodiments, the solid-state additive manufacturing process-controlled system is capable of building any cell structure 1104 on the substrate 1103, such as but not limited to triangular cell strictures (FIG. 11B), square-like cell structures (FIG. 11C), hexagonal honeycomb structures (FIG. 11D), and others, or any combination of them.

(104) In yet another embodiment, gradient (graded) honeycomb structures can be produced yielding a gradient having a particular characteristic or functionality within the final deposited structure. For instance, it has been shown that enhancement in stiffness, strength and energy absorption is possible in the direction of a positive in-plane cell gradient.

(105) In yet another embodiment, the software-controlled solid-state additive manufacturing process control system is capable of producing periodic, non-periodic cell structures, gradient cell structures, super-imposed structures (double-, triple-structures), hierarchical, composite and other complex cell structures or any of their combinations; some of them presented in FIGS. 12A and B. FIG. 12A is a schematic diagram of super-imposed hexagonal honeycomb structures 1204 on a single substrate 1203 generated by a computer-governed solid-state additive manufacturing process. Such structures have been suggested for improved strength and stiffness of the final part. FIG. 12B is a schematic diagram of a combined dual super-imposed honeycomb structure 1204A and a hierarchical honeycomb structure 1204B, matching with one of the underlaying honeycomb structures 1204A, added on top of the dual super-imposed structure, all built-up on a single substrate 1203.

(106) In some embodiments, the periodic and non-periodic structures (e.g. honeycomb structures) made with the software-controlled solid-state additive manufacturing process can be generated with well-defined or random cell structures, and the cells' wall thickness and height can be made to be the same or different (FIGS. 13A and 13B). FIG. 13A is a schematic diagram of cell structures 1304A and 1304B generated by the solid-state additive manufacturing process, where the different cells are of the same height, while the generated cells 1304A and 1304B in FIG. 13B are of different heights.

(107) In another embodiment, the computer-controlled additive manufacturing system is capable of making a simple, composite, super-imposed and hierarchical cell structure on multiple substrates for applications where tailored elastic/stiffness performance, energy absorption, damage tolerance, and/or acoustic and heat control are required (FIGS. 14A-14C).

(108) Specifically, in one embodiment, periodic structures 1404A and 1404B are generated on two or more substrates (1403A, 1403B), as presented in FIG. 14A. The cells' material in each layer can be the same or different. The major difference which distinguishes this structure from other honeycomb structures made with other types of processes is that this one does not include any adhesive layer or layers. The honeycomb structured layer(s) is directly deposited on the substrate with the solid-state additive manufacturing process, yielding a stronger final structure compared to conventional honeycomb structures where adhesive layers are used and usually provide the weakest points in the whole structure.

(109) Another embodiment related to a dual super-imposed honeycomb cell structure 1404A deposited on a substrate 1403A followed by another honeycomb structure 1404B deposited on a subsequent substrate 1403B and matching one of the superimposed structure underneath is presented in FIG. 14B. Again, there is no use of any adhesive layer, which distinguishes the shown structures from conventional simple and super-imposed honeycomb structures.

(110) In yet another embodiment, a sandwich structure of two substrates 1403A and 1403B with a honeycomb structured interlayer 1404 is shown in FIG. 14C. This structure does not comprise any adhesive layer or layers between the honeycomb cells and the substrates, which makes it intrinsically stronger than similar structures produced by conventional methods that use adhesive layers.

(111) In another embodiment, a stack of two or more sandwiched structures with honeycomb structured interlayers can be made by the computer-controlled solid-state additive manufacturing system.

(112) In another embodiment, the computer-controlled solid-state additive manufacturing process is capable of manufacturing cell structures utilizing two or more materials, e.g. a cell structure 1504A made with material A, which cells can be filled 1504B with a different material B, all deposited on a substrate 1503, as shown in FIG. 15A. In this way, a solid layer can be deposited with the additive manufacturing process which includes an embedded honeycomb structure for additional stiffness, strength and/or acoustic control.

(113) In another embodiment, the cell structure 1504A deposited on a substrate 1503 is additionally reinforced by stiffening ribs 1504B that can be simultaneously added along with the cell structures with the software-controlled solid-state additive manufacturing system as shown in FIG. 15B. The stiffening ribs 1504B can be made of the same material as the cells 1504A or with a different material.

(114) In yet another embodiment, the generated periodic or non-periodic structures on a first substrate are deformed (subjected to a controlled shape change) by the subsequent step of depositing the next layer or structures.

(115) In another embodiment, the computer-controlled additive manufacturing system is capable of fabricating the whole sandwiched structure (the outer bottom layer on a backing panel, the core cellular structure and the top layer) without using adhesive layers.

(116) In some of the embodiments, the disclosed process-controlled solid-state additive manufacturing system is capable of repairing a variety of substrates, parts and complex structures. Sometimes, when the damaged structures and parts are made of metals, MMCs, composites or sandwiched and laminated structures, the choice of conventional repair methods is very limited, and are often time-consuming and/or cost-ineffective. The flexibility of the solid-state additive technology offers unique ways for repairing complex geometries that are not possible by conventional methods.

(117) In another embodiment, the predefined additive structure fabricated by the computer-controlled additive manufacturing system is generated via 3D-printing-like processes.

(118) In another embodiment, the predefined additive structure fabricated by the computer-controlled additive manufacturing system is generated via 4D-printing-like processes, which are actually a combination of 3D printing and time as the fourth dimension. Specifically, the computer-controlled additive manufacturing machine deposits a predefined 3D structure made with a shape memory material (also known as a “smart” material). The deposited 3D structure made of shape memory material can change its shape (dimensions) over time while adapting to its surroundings and/or when subjected to certain external stimuli (e.g. electric field, magnetic field, load, light, heat, etc.)

(119) In yet another embodiment, the 3D structure made from shape memory material and deposited with the disclosed computer-controlled solid-state additive manufacturing machine is capable of reversible changes in its shape (and dimensions).

(120) In some embodiments, the solid-state additive manufacturing system is capable of depositing materials known to be antimicrobial and antifungal, such as copper, bronze, brass, Ag-containing alloys and stainless steel enriched with Ag- and Cu-ions. Such materials are very useful for applications, such as ship structures, which are in a continuous contact with sea water, where coatings that have anti-biofilm/anti-slime functionality are preferred.

(121) Moreover, in one embodiment, the software-controlled solid-state additive manufacturing system includes computer-readable code for regulating the concentrations (or volume ratio) of the incoming filler materials, when two or more materials are being added to the feeding unit of the solid-state additive manufacturing system. For instance, two powder or granular materials, material A and material B are brought independently into the feeder and mixed well. Their volume ratio or concentration of material B in material A in the final filler material 1601 can be regulated by a code for controlling the feeding streams of material A and material B in the feeder, and then the well-mixed filler can be deposited on the substrate 1603 (FIG. 16A). As an example only, aluminum (A1) powder and steel powder can be introduced into the feeder independently and mixed in a certain ratio (regulated by the code) to provide the required steel-concentration in the final deposited layer 1604 on a substrate 1603 (FIG. 16B). Furthermore, in another embodiment, such deposited layer (e.g. A1 with incorporated steel) can be further subjected to post-processing treatment to generate desirable surface micro- and/or nano-structures that can provide an additional functionality to the deposit 1604, viz. wear-resistant, self-cleaning, anti-biofilm or anti-microbial functionality.

(122) In another embodiment, the filler material 1601 can be made in a form of a hollow tube or hollow rod (made of material A) filled with another material (material B), as presented in FIGS. 16C, 16D and 16E.

(123) In some embodiments, the code can change the ratio (concentration or composition) of the filler materials with time, i.e. with the number of deposited layers, and thus, can enable a material concentration gradient in the deposited layers. In one embodiment, the material composition gradient can be achieved along the layer length 1604 deposited on a substrate 1603 as presented in FIG. 16F. In another embodiment, the material composition gradient can be achieved along the layers' thickness (deposit thickness), as presented in FIG. 16G, where the deposited layers 1604A, 1604B and 1604C gradually change in their composition. In yet another embodiment, composition (concentration) gradients are possible in both directions, along the deposition length and the deposit thickness.

(124) In some embodiments the computer-controlled solid-state additive manufacturing machine is used to join parts 1705A and 1705B placed on a backing plate 1703 in a manner in which a filler material 1701 can be introduced into the joint between the two parts (FIG. 17A) yielding the final structure presented in FIG. 17B, where the joint between the two parts 1705A and 1705B is filled with the deposit 1704. The filler material 1701 in FIG. 17A can contain reinforcing particles, fibers, CNTs and others to reinforce the final joint 1704 in FIG. 17B. In yet other embodiments, beside the joint 1704 between the two parts 1705A and 1705B, additional stiffening (strengthening) structures, such as 1704A and/or 1704B can be deposited (FIGS. 17C and 17D).

(125) In some embodiments, two parts 1805A and 1805B can be joined together without introducing the filler material 1801 into the space (in the joint) between the two parts by placing the parts in sufficiently close proximity and depositing the filler as stiffening structures 1804A and/or 1804B (FIGS. 18A-C). The filler material used for the joining process can be reinforced with carbon or glass fibers, carbon nanotubes (CNTs), metal particles and other reinforcing particles for adding strength to the joint.

(126) In some embodiments, corner joining of two parts 1905A and 1905B with filler 1901 by introducing filler in the space (joint) between the two parts is presented in FIG. 19A, yielding the joint parts with deposit 1904 as presented in FIG. 19B. In other embodiments, the corner joint can be further reinforced (strengthen) by depositing stiffening structures 1904A, 1904B and/or 1904C as presented in FIGS. 19C and 19D.

(127) In other embodiments, the corner joint is made by the solid-state additive manufacturing system without introducing filler 2001 into the space between the two parts to be joined 2005A and 2005B, but instead only stiffening structures 2004A, 2004B, 2004C and/or 2004D are added (FIGS. 20A-E).

(128) In another embodiment, a T-joint of two parts 2105A and 2105B is made by adding a filler 2101 yielding the final structure with deposited stiffening structures 2104A, 2104B, 2104C and/or 2104D as presented in FIGS. 21A and 21B. In yet another embodiment, the filler material can be deposited in the space between the two parts to be joined via the T-joint and then strengthen with the stiffening structures.

(129) In other embodiments, the solid-state additive manufacturing system is used for joining two parts or structures with simple or complex geometries. The parts can be made of the same, similar or dissimilar materials. It is worth noting that in the case of joining dissimilar materials, the number of available traditional joining processes is limited and/or these traditional joining processes have severe limitations.

(130) In one embodiment, a prepreg inter-layer 2206 is incorporated in the laminate structure between two thermoplastic plates 2204A and 2204B, as presented in FIGS. 22A-C. The plates 2204A and 2204B can be previously fabricated plates, where the machine joins the prepreg layer between the two plates by severe thermo-mechanical (friction) action provided by the tool 2202. In another embodiment, the thermoplastic plates can be deposited with the machine via supplying the filler material 2201 via the hollow tool 2202 in addition to their bonding to the prepreg interlayer by the severe thermo-mechanical action provided by the tool.

(131) The prepreg inter-layer can be a single layer prepreg impregnated with thermoplastic or thermoset polymer or can be a multi-layer prepreg (so-called prepreg laminate). The prepreg usually includes uniaxially-oriented fibers or biaxially-oriented fibers or multi-axis-oriented fibers, where the fibers can be carbon fibers, glass fibers, metal wires, and so on.

(132) In another embodiment, the plates 2304A and 2304B are made of metal, metal alloy or metal-matrix-composite (MMC) or any other composite and the prepreg inter-layer 2306 is added without using adhesive layers as presented in FIGS. 23A-C. For good bonding to the metal plates, thin thermoplastic interlayers 2304C and 2304D around the prepreg layer can be added (FIG. 23D). Already manufactured metal plates 2304A and 2304B can be used or they can be simultaneously deposited via the tool 2302.

(133) In other embodiments, the software-controlled solid-state additive manufacturing system is capable of repairing a defective substrate or a part 2407A having blind holes, surface cracks and other defects 2407B, as presented in FIG. 24A. The defects are filled with a filler material 2401 supplied via hollow rotating tool 2402. In another embodiment, when the holes and cracks 2407B are deeper in the defective substrate or structure 2407A, a backing plate 2403 is used during the repair process (FIG. 24B).

(134) Furthermore, embodiments include various designs of the feeding system and associated parts for continuous supply of the filler material to the solid-state additive manufacturing system.

(135) In an embodiment, one pair of drive rollers 2508 (or drive wheels) is used for a continuous supply of the filler rod material 2501 to the solid-state additive manufacturing system, as presented in FIG. 25A.

(136) In other embodiments, two-, three- or multiple-pairs of drive wheels 2508A, 2508B, 2508C, etc. (also called feeding or feed rollers) are employed for a continuous supply of the filler material 2501, such as a rod of filler material, to the solid-state additive manufacturing system, as presented in FIG. 25B.

(137) In some embodiments, the drive wheels have a smooth surface finish, while in other embodiments, one or more of the rollers can have a surface that is textured or includes one or more groves and/or channels, and/or a surface with roughness or special features. As an example only, FIG. 25C presents a feeding system with three pairs of rollers 2508A, 2508B and 2508C, where one pair rollers 2508C has surface features that would impact the shape of the incoming filler material 2501 for its subsequent easier friction stirring on the workpiece surface.

(138) In some embodiments, the rollers can have different shapes. In other embodiments, the rollers can have the same shape.

(139) In another embodiment, one or more of the rollers are held at ambient temperature or are heated to different temperatures (T1, T2, T3) to enable softening and/or reduction of the density of the filler material, and thus, enabling easier stirring on the workpiece surface (FIG. 25C).

(140) In some embodiment, the compartments where the sets of rollers are located, are heated to different temperatures. Temperatures T1, T2 and T3 in FIG. 25C can be different or the same depending upon the feeding material used. Usually T1<T2<T3, but any other temperature profile can be employed.

(141) In another embodiment, the gap between the rollers is variable as presented in FIGS. 25D and 25E, which is especially useful when handling filler materials such as large plastic blocks 2501 or a large pile of material 2501A that is squeezed between the rollers 2508A, 2508B and 2508C and introduced as a narrow material stream for making additive structures on a workpiece or a flat substrate.

(142) In some embodiments, the variable gap between the rollers 2508 is provided by springs 2509 (FIG. 25F) which push the rollers towards each other, and thus, provide “squeezing” or compression of the material, while pushing the material down towards the workpiece. The material compression depends on the elasticity of the spring from one side, as well as the elasticity and compression strength of the filler material being compressed on the other side.

(143) In another embodiment, the variable gap between the rollers is adjusted manually by way of screws or other means. In embodiments, the variable gap can be adjusted manually and/or automatically, for example, by way of springs.

(144) In yet another embodiment, the force on the filler bar is easily adjusted in situ by adjusting the gap between the rollers.

(145) In some embodiments, the rollers are capable of providing one or more measurements of filler bar dimensions, which measurements are valuable for estimating the volume of the material being deposited through the precise displacement of the rollers.

(146) In particular embodiments, different sets of rollers can be operated at different rates, which is helpful with re-load timing delays.

(147) In some embodiments, the filler rod material 2501 can be engaged (pushed down as presented in FIG. 25A) or disengaged between the rollers 2508, as presented in FIG. 25G. By controlling the direction of roller rotation and roller speeds, the filler material or rod is pushed towards the workpiece or is retracted (pulled away) from the workpiece.

(148) In some embodiments, the rollers 2608 have different surface structures as presented in FIGS. 26A-E. Some of the surface structures are embedded within the roller surface, e.g. groves of different cross-sectional shapes (triangular, square, rectangular) as presented in FIG. 26A. Some of these surface features are especially useful for providing stability to rod-like filler materials during feeding.

(149) In other embodiments, surface features are provided above the roller surface, e.g. crescent blades (knife-type), paddle-type blades, and so on, as presented in FIGS. 26B-E. These types of rollers can have one or more effects on the filler material, depending on the type of filler and its form. For instance, crescent-like/knife-like blades on the rollers 2708A can be used to chop filler material from a large block of material 2701A into small pieces of filler material 2701B, as presented in FIG. 27A. Paddle-type extensions on the rollers 2708B can be used to supply granular material, powder, briquettes, chopped material or any other shape of filler material 2701C to the solid-state additive manufacturing machine, as presented in FIG. 27B.

(150) In some embodiments, the feeding rollers are located inside the spindle of the solid-state additive manufacturing system, while in other embodiments, the rollers are located outside the spindle housing.

(151) In one embodiment, the solid-state additive manufacturing machine is used to recycle waste metal pieces, e.g. machine chips, shavings, scrap metal, plastic scrap pieces or flakes and so on, and deposit them for example as a continuous layer on the workpiece surface (FIG. 27B).

(152) In another embodiment, the scrap metal pieces are first pressed into a solid bar and such bar is supplied as a filler to the solid-state additive manufacturing machine.

(153) In yet another embodiment, the scrap metal pieces are first made into powder, granules or compacted into briquettes and then supplied as a filler to the solid-state additive manufacturing machine.

(154) Furthermore, any used metal pieces, such as bullet casings and shotgun shells and/or other bullet casings can be used as a filler material in the feeding system of the present invention. The used metal pieces can be first chopped into smaller pieces and then supplied to the feeding system, or the feeding system can have a section for chopping or shredding large pieces into smaller pieces.

(155) In one embodiment, the waste metal pieces are used cans 2701A (FIG. 27C) that can be shredded or chopped with rollers with crescent blades 2708A in the feeding section of the solid-state additive manufacturing system and consequently used as a filler material 2701B.

(156) In another embodiment, the feeding system is capable of shredding used plastic objects, e.g. bottles 2701A (FIG. 27D) by way of feeding rollers with crescent blades 2708A, and such shredded material 2701B can then be used as a filler material in the solid-state additive manufacturing process.

(157) In some embodiments the filler material to be supplied to the solid-state additive manufacturing machine is a rod-like material. The rods can be of different shapes, e.g. with square, round, triangular or rectangular cross-sections, examples shown as 2801A, 2801B and 2801C in FIGS. 28A, 28B and 28C, respectively.

(158) In one embodiment, the feeding rollers have one grove (channel) 2808A for a continuous and stable supply of a rod filler material with a square cross-sectional shape 2801 (FIG. 28B).

(159) In yet another embodiment, the rollers have two or more channels (grooves) on their surface 2808B, which are capable of providing a continuous and stable supply of two or more rods of filler materials 2801A, 2801B and 2801C (FIG. 28C). The rods can be made of same material or different materials, which upon passing through heated rollers consolidate and yield in situ MMC, alloy, blend, or composite materials, and as such multicomponent materials can then be deposited onto the workpiece.

(160) In some embodiments, the sets of rollers 2808C are capable of continuously accepting and pushing down plates, films and sheets of the filler material 2801D (FIG. 28D). For instance, many plastics come in the form of plates, sheets or films. Without any prior preparation, such as making pellets or granules, or cutting the sheets into rods, the gap between the rollers can be adjusted to accept and push down the particular plate/sheet/film according to the thickness that the filler material is available in.

(161) In other embodiments, two or more sheets or films of the same or different filler materials 2801D, 2801E and 2801F are continuously supplied through heated rollers 2808C, where they are being consolidated into a single blend, mixture, alloy, composite material, and then, as such an in situ manufactured composite or hybrid material is then supplied to the solid-state additive manufacturing machine (FIG. 28E).

(162) In some embodiments, the filler material is supplied in a powder form or as granules, beads, flakes, pellets, briquettes, chopped fibers or chopped wires. One or multiple types of materials 2901A and 2901B can be supplied via feeding ports 2910A and 2910B. Additives or liquids can be added (injected) via a special port 2911. To provide a continuous supply of well-mixed filler components, an auger screw 2917 and an agitator 2915 with agitator arms 2916 can be included in the feeding section, i.e. hopper 2913, as presented in FIG. 29A. The cover 2914 is optional and serves the purpose of suppressing release of volatile compounds and dust into the surrounding environment. To enable better mixing of the starting filler components, a heater 2918 can be added to the hopper or along its walls. The final material stream 2901C is mixed in the feeding/hopper section serves as the filler material supplied to the subsequent section of the solid-state additive manufacturing system (i.e. to the spindle) (FIG. 29A).

(163) In yet other embodiments, the drive wheels in the feeding section are not only used to provide a continuous supply of filler, but also for mixing, compression, consolidation, squeezing/kneading, cutting, or chopping of the initial fillers.

(164) In some embodiments, the feeding section is equipped with multiple ports 2910A, and 2910B, such as a port for liquid (additives) injection 2911 and a port for venting (or degassing) 2912, as presented in FIG. 29A.

(165) In a particular embodiment, the auger screw 2917 and the agitator 2915 with agitator arms 2916 are introduced into the feeding system (FIG. 29A). One, two or more materials 2901A, 2901B, etc. are supplied via filler materials ports 2910A, 2910B, etc. and mixed well in the entrance section (hopper) 2913 of the feeding system. In addition, a variety of additives (in solid or liquid form), such as lubricants, plasticizers, UV-, ozone- or thermal-stabilizers and others can be supplied in this section via specially designed ports (or injection ports) 2911, or the additives can be mixed together with the filler material prior to the fillers' entrance into the feeding system.

(166) In yet another embodiment, the feeding section is equipped with an agitator 2915 and agitator arms 2916, while the auger screw 2917 is located in the spindle 2919, as presented in FIG. 29B. Heater units 2918A and 2918B can be added to the hopper 2913 and the spindle 2919, respectively.

(167) The auger screw 2917 from the feeding section can extend to other sections of the solid-state additive manufacturing system, e.g. in the spindle 2919 and the tool 2902, as presented in FIG. 29C.

(168) In some embodiments, the feeding section is equipped with a heater 2918, which can be any type of heat exchanger, wall heater, etc. In a particular embodiment, the hopper can be heated inside its cavity or by way of surface heating of the hopper walls.

(169) In another embodiment, a vibration is provided in the hopper and/or other sections of the solid-state additive manufacturing system to enable better mixing and supply of the filler material to the next section of the solid-state additive manufacturing system.

(170) In a particular embodiment, the hopper is equipped with an agitator 2915 and agitator arms 2916 to mix the filler materials in powder, granular, bead, pellet, flakes, and/or briquette form or their combinations along with the additives (lubricants, plasticizers, stabilizers). Then the spindle 2919 with auger screw 2917 is used to further mix and supply the mixed material into the next section of the solid-state additive manufacturing system (FIG. 29B).

(171) In another embodiment, in addition to the agitator, the auger screw is used in the hopper, which extends also in the spindle and the hollow tool (FIG. 29C). The auger screw 2917 can have the same design in all three sections, i.e. in the hopper 2913, the spindle 2919 and the tool 2902, or can vary in diameter and pitch as it extends from one section into another.

(172) In another embodiment, the auger screw for a continuous supply of a filler material is used only in the hollow tool 2902. This particular design can provide quick changes in the flow rate of the filler on the workpiece.

(173) The auger screw designs, used for a continuous supply of materials in a powder, granular, pellet, bead, briquette, flake and other forms, can vary and several examples used in embodiments of the present invention are shown in FIG. 30. For instance, examples of auger screws with constant pitch 2917A (FIG. 30A), variable pitch 2917B (FIG. 30B), variable depth 2917D (FIG. 30D), variable pitch and depth 2917C (FIG. 30C), variable diameter screws 2917E (FIG. 30E), screws with specific endings 2917F (FIG. 30F), twin- or double-auger screws 2917G and 2917H, respectively are shown in FIGS. 30G and 30H. Auger screws with full-pitch, half-pitch segments, tapered- or ribbon-segments can also be used, depending on the material type or form needed to be supplied. Screws with paddle-type blades or crescent-type blades can also be used in certain embodiments.

(174) In some embodiments, the auger screw has a pitch in the range between 10 inches and 0.1 inch, more preferably between 2 inches and 0.2 inches, and most preferably in the range of between 1 inch and 0.3 inches.

(175) In some embodiments, the auger screw has a thread with specific designs that provide less wearing of the threads. For instance, in one embodiment, the front side of the thread is designed to be perpendicular to the auger screw axis. In yet another embodiment, the back side of the thread is such that it has an angle between 10 degrees and 50 degrees, and more preferably between 20 degrees and 30 degrees, with respect to the auger screw axis.

(176) In other embodiments, shaftless flights, or sectional flights (individual turns, helicoidal flights, wraps) are used to move larger pieces of filler materials (e.g. chopped plastic bottles, used bullet casings), sticky materials, lumps, and so on, especially in the entrance section of the feeding system.

(177) In some embodiments, the feeding system is capable of supplying filler material in a form of beads, granules, pellets, briquettes, flakes, fibers (chopped, continuous), irregular or regular shaped particles and their combinations.

(178) In yet other embodiments, besides the filler material, the feeding system is capable of supplying additives such as lubricants (powder, liquid, gels), plasticizers, stabilizers (UV-, ozone-, thermal-stabilizers), reinforcers, fillers and so on, to the solid-state additive manufacturing machine.

(179) The system(s) of the invention can include, at a minimum, one or more computer processor(s) for carrying out the computer-executable instructions of the invention. In addition, or alternatively, the system(s) can include a conventional computer or specialized computer with components such as one or more processor(s), memory, hard drive, graphics processing unit (GPU), and input/output devices such as display, keyboard, and mouse. Such computer can be in communication with the solid-state additive manufacturing machine by way of a wired or wireless connection for issuing commands to various components of the solid-state additive manufacturing machine such as the actuator, or any other actuator, motor, or controller described herein. Further, such computer may be in a wired or wireless communication with any sensor, gauge, or detector described herein for providing inputs to any software, firmware, or hardware for carrying out the methods of the invention. The processor(s) or computer can be separate from the machine or can be integrated with the machine (e.g. share a housing).

(180) The system can also include a non-transitory computer storage media such as RAM which stores a set of computer executable instructions (software) for instructing the processors to carry out any of the methods described in this disclosure. As used in the context of this specification, a “non-transitory computer-readable medium (or media)” may include any kind of computer memory, including magnetic storage media, optical storage media, nonvolatile memory storage media, and volatile memory. Non-limiting examples of non-transitory computer-readable storage media include floppy disks, magnetic tape, conventional hard disks, CD-ROM, DVD-ROM, BLU-RAY, Flash ROM, memory cards, optical drives, solid state drives, flash drives, erasable programmable read only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), non-volatile ROM, and RAM. The non-transitory computer readable media can include the set of computer-executable instructions for providing an operating system as well as a set of computer-executable instructions, or software, for implementing the methods of the invention.

(181) According to embodiments, the solid-state additive manufacturing machine may be or include any tool described or depicted in US Application Publication Nos. 2010/0285207, 2012/0279441, 2015/0165546, 2017/0216962, which are hereby incorporated by reference herein in their entireties. According to one embodiment, the machine comprises a friction-based fabrication tool comprising: a non-consumable body formed from material capable of resisting deformation when subject to frictional heating and compressive loading and a throat defining a passageway lengthwise through the body and shaped for exerting normal forces on a material in the throat during rotation of the body.

(182) According to another embodiment, the machine comprises a non-consumable member having a body and a throat; wherein the throat is shaped to exert a normal force on a consumable material disposed therein for imparting rotation to the coating material from the body when rotated at a speed sufficient for imposing frictional heating of the coating material against a substrate; wherein the body is operably connected with a downward force actuator for dispensing and compressive loading of the consumable material from the throat onto the substrate and with one or more actuators or motors capable of rotating and translating the body relative to the substrate; wherein the body comprises a surface capable of trapping the consumable material loaded on the substrate in a volume between the body and the substrate and forming and shearing a surface of a coating on the substrate.

(183) Other specific embodiments include friction-based fabrication tools comprising: (a) a spindle member comprising a hollow interior capable of housing a consumable coating or filler material disposed therein prior to deposition on a substrate; wherein the interior of the spindle is shaped to exert a normal force on the consumable material disposed therein for rotating the consumable material during rotation of the spindle; (b) a downward force actuator, in operable communication with the spindle, capable of dispensing and compressive loading of the consumable material from the spindle onto the substrate and with one or more motors or actuators for rotating and translating the spindle relative to the substrate; and wherein the spindle comprises a shoulder surface with a flat surface geometry or a surface geometry with structure capable of enhancing mechanical stirring of the loaded consumable material, which shoulder surface is operably configured for trapping the loaded consumable material in a volume between the shoulder and the substrate and forming and shearing a surface of a coating on the substrate.

(184) In some embodiments, the throat has a non-circular cross-sectional shape. Additionally, any filler material can be used as the consumable material, including consumable solid, powder, or powder-filled tube type coating materials. In the case of a powder-type coating material, the powder can be loosely or tightly packed within the interior throat of the tool, with normal forces being more efficiently exerted on tightly packed powder filler material. Packing of the powder filler material can be achieved before or during the coating process.

(185) Further provided are tooling configurations comprising any configuration described in this disclosure, or any configuration needed to implement a method according to the invention described herein, combined with a consumable filler material member. Thus, tooling embodiments of the invention include a non-consumable portion (resists deformation under heat and pressure) alone or together with a consumable coating material or consumable filler material (e.g., such consumable materials include those that would deform, melt, or plasticize under the amount of heat and pressure the non-consumable portion is exposed to).

(186) Another aspect of the present invention is to provide a method of forming a surface layer on a substrate, such as repairing a marred surface, building up a surface to obtain a substrate with a different thickness, joining two or more substrates together, or filling holes in the surface of a substrate. Such methods can comprise depositing a coating or filler material on the substrate with tooling described in this disclosure, and optionally friction stirring the deposited coating material, e.g., including mechanical means for combining the deposited coating material with material of the substrate to form a more homogenous coating-substrate interface. Depositing and stirring can be performed simultaneously, or in sequence with or without a period of time in between. Depositing and stirring can also be performed with a single tool or separate tools, which are the same or different.

(187) Particular methods include depositing a coating on a substrate using frictional heating and compressive loading of a coating material against the substrate, where a tool supports the coating material during frictional heating and compressive loading and is operably configured for forming and shearing a surface of the coating.

(188) In embodiments, the tool and consumable material preferably rotate relative to the substrate. The tool can be attached to the consumable material and optionally in a manner to allow for repositioning of the tool on the coating material. Such embodiments can be configured to have no difference in rotational velocity between the coating material and tool during use. The consumable material and tool can alternatively not be attached to allow for continuous or semi-continuous feeding or deposition of the consumable material through the throat of the tool. In such designs, it is possible that during use there is a difference in rotational velocity between the consumable material and tool during the depositing. Similarly, embodiments provide for the consumable material to be rotated independently or dependently of the tool.

(189) Preferably, the consumable material is delivered through a throat of the tool and optionally by pulling or pushing the consumable material through the throat. In embodiments, the consumable material has an outer surface and the tool has an inner surface, wherein the outer and inner surfaces are complementary to allow for a key and lock type fit. Optionally, the throat of the tool and the consumable material are capable of lengthwise slideable engagement. Even further, the throat of the tool can have an inner diameter and the consumable material can be a cylindrical rod concentric to the inner diameter. Further yet, the tool can have a throat with an inner surface and the consumable material can have an outer surface wherein the surfaces are capable of engaging or interlocking to provide rotational velocity to the consumable material from the tool. In preferred embodiments, the consumable filler or coating material is continuously or semi-continuously fed and/or delivered into and/or through the throat of the tool. Shearing of any deposited consumable material to form a new surface of the substrate preferably is performed in a manner to disperse any oxide barrier coating on the substrate.

(190) Yet another aspect of the present invention is to provide a method of forming a surface layer on a substrate, which comprises filling a hole in a substrate. The method comprises placing powder of a fill material in the hole(s) and applying frictional heating and compressive loading to the fill material powder in the hole to consolidate the fill material.

(191) In yet another embodiment, the machine, in addition to including a tool described in this specification, includes a substrate. Materials that can serve as the consumable filler material or as the substrate(s) can include metals and metallic materials, polymers and polymeric materials, ceramic and other reinforced materials, as well as combinations of these materials. In embodiments, the filler material can be of a similar or dissimilar material as that of the substrate material(s). The filler material and the substrate(s) can include polymeric material or metallic material, and without limitation can include metal-metal combinations, metal matrix composites, polymers, polymer matrix composites, polymer-polymer combinations, metal-polymer combinations, metal-ceramic combinations, and polymer-ceramic combinations.

(192) In one particular embodiment, the substrate(s) and/or the filler material are metal or metallic. The filer material, or the substrate(s) can be independently selected from any metal, including for example A1, Ni, Cr, Cu, Co, Au, Ag, Mg, Cd, Pb, Pt, Ti, Zn, or Fe, Nb, Ta, Mo, W, or an alloy comprising one or more of these metals. In embodiments, the substrate(s) and/or the filler material are polymeric material. Non-limiting examples of polymeric materials useful as a filler material include polyolefins, polyesters, nylons, vinyls, polyvinyls, acrylics, polyacrylics, polycarbonates, polystyrenes, polyurethanes, and the like.

(193) In still yet another embodiment, the filler material is a composite material comprising at least one metallic material and at least one polymeric material. In other embodiments, multiple material combinations can be used for producing a composite at the interface.

(194) The filler materials can be in several forms, including but not limited to: 1) a metal powder or rod of a single composition; 2) mixed matrix metal and reinforcement powders; or 3) a solid rod of matrix bored to create a tube or other hollow cylinder type structure and filled with reinforcement powder, or mixtures of metal matric composite and reinforcement material. In the latter, mixing of the matrix and reinforcement can occur further during the fabrication process. In embodiments, the filler material may be a solid metal rod. In one embodiment, the filler material is aluminum.

(195) According to embodiments, the filler material and/or the substrate(s) are independently chosen from plastics, homo polymers, co-polymers, or polymeric materials comprising polyesters, nylons, polyvinyls such as polyvinyl chloride (PVC), polyacrylics, polyethylene terephthalate (PET or PETE), polylactide, polycarbonates, polystyrenes, polyurethanes, and/or polyolefins such as high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene, composites, mixtures, reinforcement materials, or a metal matrix composite comprising a metal matrix and a ceramic phase, wherein the metal matrix comprises one or more of a metal, a metal alloy, or an intermetallic, and the ceramic phase comprises a ceramic, and independently chosen from metallic materials, metal matrix composites (MMCs), ceramics, ceramic materials such as SiC, TiB2 and/or Al.sub.2O.sub.3, metals comprising steel, Al, Ni, Cr, Cu, Co, Au, Ag, Mg, Cd, Pb, Pt, Ti, Zn, Fe, Nb, Ta, Mo, W, or an alloy comprising one or more of these metals, as well as combinations of any of these materials

(196) The present invention has been described with reference to particular embodiments having various features. In light of the disclosure provided above, it will be apparent to those skilled in the art that various modifications and variations can be made in the practice of the present invention without departing from the scope or spirit of the invention. One skilled in the art will recognize that the disclosed features may be used singularly, in any combination, or omitted based on the requirements and specifications of a given application or design. When an embodiment refers to “comprising” certain features, it is to be understood that the embodiments can alternatively “consist of” or “consist essentially of” any one or more of the features. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention.

(197) It is noted in particular that where a range of values is provided in this specification, each value between the upper and lower limits of that range is also specifically disclosed. The upper and lower limits of these smaller ranges may independently be included or excluded in the range as well. The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. It is intended that the specification and examples be considered as exemplary in nature and that variations that do not depart from the essence of the invention fall within the scope of the invention. Further, all of the references cited in this disclosure are each individually incorporated by reference herein in their entireties and as such are intended to provide an efficient way of supplementing the enabling disclosure of this invention as well as provide background detailing the level of ordinary skill in the art.