PROPERTY MODULATED MATERIALS AND METHODS OF MAKING THE SAME

Abstract

A method of making property modulated composite materials includes depositing a first layer of material having a first microstructure/nanostructure on a substrate followed by depositing a second layer of material having a second microstructure/nanostructure that differs from the first layer. Multiple first and second layers can be deposited to form a composite material that includes a plurality of adjacent first and second layers. By controlling the microstructure/nanostructure of the layers, the material properties of the composite material formed by this method can be tailored for a specific use. The microstructures/nanostructures of the composite materials may be defined by one or more of grain size, grain boundary geometry, crystal orientation, and a defect density.

Claims

1.-17. (canceled)

18. A method, comprising: contacting a portion of a substrate with a bath including at least two electrodepositable species; forming a property modulated composite on the portion of the substrate by: applying a current to the substrate at a first setting having a first determined value of beta for a first duration, beta being defined as a ratio of a value of peak cathodic current density to an absolute value of peak anodic current density, the current having a current density that is a sine waveform, the first setting producing a first material comprising the at least two electrodepositable species, the first material having a first composition and a first nanostructure defined by one or more of a first average grain size, a first grain boundary geometry, a first crystal orientation, and a first defect density; and applying the current to the substrate at a second setting having a second determined value of beta for a second duration, the second setting producing a second material comprising the at least two electrodepositable species, the second material having a second composition and a second nanostructure defined by one or more of a second average grain size, a second grain boundary geometry, a second crystal orientation, and a second defect density, where one or more of the first average grain size differs from the second average grain size, the first grain boundary geometry differs from the second grain boundary geometry, the first crystal orientation differs from the second crystal orientation, or the first defect density differs from the second defect density.

19. The method of claim 18, wherein beta is changed from the first determined value to the second determined value as a continuous function of time.

20. The method of claim 18, wherein the property modulated composite is a layered property modulated composite.

21. The method of claim 20, wherein the layered property modulated composite comprises alternating first and second layers produced by the passing the current through the substrate at the first and second settings.

22. The method of claim 20, wherein a first layer of the layered property modulated composite exhibits a first mechanical property and a second layer of the layered property modulated composite, which is adjacent to the first layer, exhibits a second mechanical property, which differs from the first mechanical property.

23. The method of claim 22, wherein the first mechanical property and the second mechanical property are selected from the group consisting of hardness, elongation, tensile strength, elastic modulus, stiffness, impact toughness, abrasion resistance, and combinations thereof.

24. The method of claim 20, wherein a first layer of the layered property modulated composite exhibits a first thermal property and a second layer of the layered property modulated composite, which is adjacent to the first layer, exhibits a second thermal property, which differs from the first thermal property.

25. The method of claim 24, wherein the first thermal property and the second thermal property are selected from the group consisting of coefficient of thermal expansion, melting point, thermal conductivity, and specific heat.

26. The method of claim 20, wherein the layered property modulated composite includes a plurality of layers, each layer of the plurality of layers having a thickness ranging from about 1 nanometer to about 10,000 nanometers.

27. The method of claim 18, wherein the property modulated composite is a graded property modulated composite.

28. The method of claim 18, wherein the first determined value of beta is less than 1.3 and the second determined value of beta is greater than 1.5.

29. The method of claim 18, wherein the current density has a DC offset.

30. The method of claim 29, wherein the current density has substantially a same DC offset while the current is applied to the substrate.

31. The method of claim 18, wherein the current maintains substantially a same peak cathodic current density and substantially a same peak anodic current density while the current is applied to the substrate.

32. The method of claim 18, wherein the current has substantially a same peak-to-peak current density while the current is applied to the substrate.

33. The method of claim 18, wherein a temperature of the bath is maintained while the current is applied to the substrate.

34. The method of claim 18, wherein the at least two electrodepositable species comprises two or more metals.

35. The method of claim 34, wherein the one or more metals comprise nickel, iron, cobalt, copper, zinc, manganese, platinum, palladium, hafnium, zirconium, chromium, tin, tungsten, molybdenum, phosphorous, barium, yttrium, lanthanum, rhodium, iridium, gold, or silver.

36. The method of claim 35, wherein the two or more metals comprise nickel, iron, zinc, cobalt, chromium, or a combination thereof

37. The method of claim 18, further comprising removing the property modulated composite from the substrate.

38. The method of claim 18, wherein the current has substantially a same frequency while the current is applied to the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are not necessarily to scale; the emphasis instead being placed upon illustrating the principles of the disclosure.

[0030] FIG. 1A is an illustration of alternating strong layers and ductile layers to form a composite.

[0031] FIG. 1B illustrates the stress versus strain curve for an individual strong layer. FIG. 1C illustrates the stress versus strain layer for an individual ductile layer. FIG. 1D illustrates the stress versus strain curve showing improved performance of the composite (combination of strong and ductile layers).

[0032] FIG. 2 is an illustration of a composite including grain size modulation.

[0033] FIG. 3A is an illustration of a composite including modulated grain boundary geometry. FIG. 3B is an illustration of another composite including modulated grain boundary geometry.

[0034] FIG. 4 is an illustration of an NMC in accordance with the present disclosure that includes layers that alternate between two different preferred orientations.

[0035] FIG. 5 is an illustration of another NMC whose layers alternate between preferred and random orientations.

[0036] FIG. 6 is an illustration of another NMC whose layers possess alternating high and low defect densities.

[0037] FIG. 7 is an illustration of another NMC whose layers possess defects of opposite sign. The borders between the layers are darkened for clarity.

[0038] FIG. 8 is a graph of Vicker's microhardness versus plating bath temperature for an iron (Fe) material electrodeposited in accordance with the present disclosure.

[0039] FIG. 9 is a graph of ultimate tensile strength and percentage of elongation versus frequency for an electrodeposited Fe in accordance with the present disclosure.

[0040] FIG. 10 is an illustration of terminology that may be used to describe a sine wave function used to control the current density in the electrodeposition/electroformation process. Positive values of J (current density) are cathodic and reducing, whereas negative values are anodic and oxidizing. For net electrodeposition to take place with a sine wave function the value of must be greater than one (i.e.. J.sub.offset must be greater than one).

DETAILED DESCRIPTION

[0041] I. Modulation of Properties

[0042] In one embodiment, property modulated composites are provided comprising a plurality of alternating layers, in which those layers have specific mechanical properties, such as, for example, tensile strength, elongation, hardness, ductility, and impact toughness, and where the specific mechanical properties are achieved by altering the nanostructure of those layers. This embodiment is illustrated in FIGS. 1A-1D.

[0043] In general, tensile strength may be controlled through controlling frequency of a signal used for electrodepositing a material. In general, percentage of elongation of a material can also be controlled through frequency. In general, hardness, ductility, and impact toughness can be controlled through controlling deposition temperature. Other methods for controlling tensile strength, elongation, hardness, ductility and impact toughness are also envisioned.

[0044] Another embodiment provides property modulated composite comprising a plurality of alternating layers, in which those layers have specific thermal properties, such as thermal expansion, thermal conductivity, specific heat, etc. and where the specific thermal properties are achieved by altering the nanostructure of those layers.

2. Modulation of Structure

[0045] Another embodiment provides NMCs comprising a plurality of alternating layers of at least two nanostructures, in which one layer has substantially one grain size and another layer has substantially another grain size, and where the grain sizes may range from smaller than 1 nanometer to larger than 10,000 nanometers. Such a structure is illustrated in FIG. 2. Smaller grain sizes, which can range, e.g., from about 0.5 nanometers to about 100 nanometers, generally will yield layers that generally exhibit high impact toughness. Large grain sizes, which generally will be greater than 1,000 nanometers, such as, for example, 5,000 or 10,000 nanometers and generally will produce layers that provide greater ductility. Of course, the grain sizes will be relative within a given group of layers such that even a grain size in the intermediate or small ranges described above could be deemed large compared to, e.g., a very small grain size or small compared to a very large grain size.

[0046] Generally, such grain sizes can be controlled through process parameters, such as, for example deposition temperature (e.g., electrodeposition bath temperature). To modulate grain size utilizing temperature control, a first layer defined by large grains can be formed by increasing the deposition temperature and a second layer defined by smaller grains can be formed by decreasing the temperature. (The material composition does not change between the first and second layersonly the grain size modulates).

[0047] The thickness of the individual layers in the NMCs can range from about 0.1 nanometer to about 10,000 nanometers or more. Layer thickness may range from about 5 nanometers to 50 nanometers, although varied thicknesses are expressly envisioned. The NMCs may contain anywhere from 2-10, 10-20, 20-30, 30-50, 75-100, 100-200, or even more layers, with each layer being created with a desired thickness, and nanostructure/microstructure.

[0048] When structural modulations are characterized by individual layer thicknesses of 0.5-5 nanometers, it is possible to produce materials possessing a dramatically increased modulus of elasticity, or supermodulus. The modulated structural trait can include, for example, one or more of grain size, preferred orientation, crystal type, degree of order (e.g., gamma-prime vs. gamma), defect density, and defect orientation.

[0049] In another embodiment, NMCs can comprise a plurality of alternating layers of at least two nanostructures, in which one layer has substantially one inter-grain boundary geometry and another layer has substantially another inter-grain boundary geometry, as illustrated in FIGS. 3A and 3B.

[0050] In still another embodiment, NMCs can comprise a plurality of alternating layers of at least two nanostructures, in which one layer has substantially one crystal orientation and another layer has substantially another crystal orientation (FIG. 4), or no preferred orientation (FIG. 5).

[0051] In still another embodiment, NMCs can comprise a plurality of alternating layers of at least two nanostructures, in which one layer has grains possessing a substantially higher defect density and another layer has grains possessing a substantially lower defect density, an example of which is illustrated schematically in FIG. 6. Similarly, embodiments can include materials whose layers alternate between defect orientation or sign, as illustrated in FIG. 7.

[0052] In still another embodiment, NMCs or NGCs can comprise a plurality of alternating layers or diffuse zones of at least two nanostructures. Each layer or zone has a mechanical, thermal, and/or electrical property associated with it, which is a distinct property as compared to an adjacent layer or zone. For example, a NMC can include a plurality of first layers each of which have a Vicker's microhardness value of 400 and a plurality of second layers each of which have a Vicker's microhardness value of 200. The NMC is formed such that on a substrate the first and second layers alternate so that each of the deposited layers has a distinct mechanical property as compared to the layer's adjacent neighbor (i.e., the mechanical properties across an interface between first and second layers are different). In some embodiments, property modulation in Vicker's hardness is created by alternating the deposition temperature in an electrochemical cell. Referring to FIG. 8, the first layers having a Vicker's microhardness value of 400 can be formed by electrodepositing Fe at a temperature 60 C., whereas second layers having a Vicker's microhardness value of 200 can be deposited at a temperature of 90 C.

[0053] In other embodiments, mechanical or thermal properties of NMCs or NGCs can be controlled through other deposition conditions such as, for example, frequency of an electrical signal used to electrodeposit layers on a substrate. In general, by increasing the frequency of the signal utilized in electrodeposition of a material, an increase in ductility (e.g., increase in ultimate tensile strength and percentage elongation) can be realized as illustrated in FIG. 9.

[0054] In addition to the frequency, the wave form of the electrical signal used to electrodeposit layers can also be controlled. For example, a sine wave, a square wave, a triangular wave, sawtooth, or any other shaped wave form can be used in electrodeposition. In general, the frequency of the waves can very from very low to very high, e.g., from about 0.01 to about 1,000 Hz, with ranges typically being from about 1 to about 400 Hz (e.g., 10 Hz to 300 Hz, 15 Hz to 100 Hz). The current also can be varied. Currents ranging from low to high values are envisioned, e.g., from about 1 to about 400 mA/cm.sup.2, with typical ranges being from about 10 to about 150 mA/cm.sup.2, in particular, 20 to 100 mA/cm.sup.2.

3. Production Processes

[0055] One embodiment provides a process for the production of a property modulated composite comprising multiple layers with discrete nanostructures. This process comprises the steps of:

[0056] i) providing a bath containing an electrodepositable species (i.e., a species which when deposited through electrodeposition forms a material, such as a metal);

[0057] ii) providing a substrate upon which the metal is to be electrodeposited;

[0058] iii) immersing said substrate in the bath;

[0059] iv) passing an electric current through the substrate so as to deposit the metal onto the substrate; and

[0060] v) heating and cooling the bath or the substrate according to an alternating cycle of predetermined durations between a first value which is known to produce one grain size and a second value known to produce a second grain size.

[0061] Another embodiment provides a process for the production of a property modulated composite comprising multiple layers with discrete nanostructures. This process comprises the steps of:

[0062] i) providing a bath containing an electrodepositable species (e.g., a species which forms a metal when electrodeposited);

[0063] ii) providing a substrate upon which the metal is to be electrodeposited;

[0064] iii) immersing the substrate in the bath; and

[0065] iv) passing an electric current through the substrate in an alternating cycle of predetermined frequencies between a first frequency which is known to produce one nanostructure and a second frequency known to produce a second nanostructure.

[0066] Another embodiment provides a process for the production of a property modulated composite comprising multiple layers with discrete nanostructures. This process comprises the steps of:

[0067] i) providing a bath containing an electrodepositable species (e.g., a species which forms a metal when electrodeposited);

[0068] ii) providing a substrate upon which the metal is to be electrodeposited;

[0069] iii) immersing the substrate in the bath;

[0070] iv) passing an electric current through the substrate in an alternating cycle of predetermined frequencies between a first frequency which is known to produce one nanostructure and a second frequency known to produce a second nanostructure, while at the same time heating and cooling the bath or the substrate according to an alternating cycle of predetermined durations between a first value and a second value.

[0071] Additional embodiments relate to processes for the production of a material where production parameters may be varied to produce variations in the material nanostructure, including beta, peak-to-peak current density, average current density, mass transfer rate, and duty cycle, to name a few.

[0072] In embodiments, the bath includes an electrodepositable species that forms an iron coating/layer or an iron alloy coating/layer. In other embodiments, the bath includes an electrodepositable species that forms a metal or metal alloy selected from the group consisting of nickel, cobalt, copper, zinc, manganese, platinum, palladium, hafnium, zirconium, chromium, tin, tungsten, molybdenum, phosphorous, barium, yttrium, lanthanum, rhodium, iridium, gold, silver, and combinations thereof.

[0073] Though the discussion and examples provided herein are directed to metallic materials, it is understood that the instant disclosure is equally applicable for metal oxides, polymers, intermetallics, and ceramics (all of which can be produced using deposition techniques with or without subsequent processing, such as thermal, radiation or mechanical treatment).

EXAMPLES

[0074] The following examples are merely intended to illustrate the practice and advantages of specific embodiments of the present disclosure; in no event are they to be used to restrict the scope of the generic disclosure.

Example I

Temperature Modulation

[0075] One-dimensionally modulated (laminated) materials can be created by controlled, time-varying electrodeposition conditions, such as, for example, current/potential, mass transfer/mixing, or temperature, pressure, and, electrolyte composition. An example for producing a laminated, grain-size-modulated material is as follows:

[0076] 1. Prepare an electrolyte consisting of 1.24M FeCl.sub.2 in deionized water.

[0077] 2. Adjust the pH of the electrolyte to 0.5-1.5 by addition of HCl.

[0078] 3. Heat the bath to 95 C. under continuous carbon filtration at a flow rate of 2-3 turns (bath volumes) per minute.

[0079] 4. Immerse a titanium cathode and low-carbon steel anode into the bath and apply a current such that the plating current on the cathode is at least 100 mA/cm.sup.2.

[0080] 5. Raise and lower the temperature of the bath, between 95 C. (large grains) and 80 C. (smaller grains) at the desired frequency, depending on the desired wavelength of grain size modulation. Continue until the desired thickness is obtained.

[0081] 6. Remove the substrate and deposit from the bath and immerse in deionized (DI) water for 10 minutes.

[0082] 7. Pry the substrate loose from the underlying titanium to yield a free-standing, grain-size modulated material.

Example II

Beta Modulation

[0083] This example involves electroplating NMCs by modulating the beta value. In embodiments where the current density is applied as a sine wave having (1) a peak cathodic current density value (J.sub.1>0), (2) a peak anodic current density value (J.sub.<0), and (3) a positive DC offset current density to shift the sine wave vertically to provide a net deposition of material, properties of the deposited layers or sections can be modulated by changing a beta value. (See FIG. 10). The beta value is defined as the ratio of the value of peak cathodic current density to the absolute value of peak anodic current density. At low beta value (<1.3), the electroplated iron layers have low hardness and high ductility, while at high beta (>1.5), the plated iron layers have high hardness and low ductility. The laminated structure with modulated hardness and ductility makes the material stronger than homogeneous material.

[0084] The electroplating system includes a tank, electrolyte of FeCl.sub.2 bath with or without CaCl.sub.2, computer controlled heater to maintain bath temperature, a power supply, and a controlling computer. The anode is low carbon steel sheet, and cathode is titanium plate which will make it easy for the deposit to be peeled, off. Carbon steel can also be used as the cathode if the deposit does not need to be peeled off from the substrate. Polypropylene balls are used to cover the bath surface in order to reduce bath evaporation.

[0085] The process for producing an iron laminate is as follows:

[0086] 1. Prepare a tank of electrolyte consisting of 2.0 M FeCl.sub.2 or 1.7 M FeCl.sub.2 plus 1.7 CaCl.sub.2 in deionized water.

[0087] 2. Adjust the pH of the electrolyte to 0.5-1.5 by addition of HCl.

[0088] 3. Control the bath temperature at 60 C.

[0089] 4. Clean the titanium substrate cathode and low carbon steel sheet anode with deionized water and immerse both of them into the bath.

[0090] 5. To start electroplating a high ductility layer, turn on the power supply, and controlling the power supply to generate a shifted sine wave of beta 1.26, by setting the following parameters: 250 Hz with a peak current cathodic current density of 43 mA/cm.sup.2 and a peak anodic current density of 34 mA/cm.sup.2 applied to the substrate (i.e., a peak to peak current density of 78 mA/cm.sup.2 with a DC offset of 4.4 mA/cm.sup.2). Continue electroplating a for an amount of time necessary to achieve the desired high ductility layer thickness.

[0091] 6. To continue electroplating a high hardness layer, change the power supply wave form using the computer, with a beta value of 1.6, by setting the following parameters: 250 Hz with a peak current cathodic current density of 48 mA/cm.sup.2 and a peak anodic current density of 30 mA/cm.sup.2 applied to the substrate (i.e., a peak to peak current density of 78 mA/cm.sup.2 with a DC offset of 9.0 mA/cm.sup.2). Continue electroplating for an amount of time needed to achieve the desired high hardness layer thickness. (Optionally, the temperature can be decreased to 30 C. during this deposition step to further tailor the hardness of the layer.)

[0092] 7. Remove the substrate and deposit from the bath and immerse in DI water for 10 minutes and blow it dry with compressed air.

[0093] 8. Peel the deposit from the underlying titanium substrate to yield a free-standing temperature modulated laminate.

Example Frequency Modulation

[0094] This example describes a process of electroplating NMCs by modulating the frequency of the wave-form-generating power supply. The wave-form can have any shape, including but not limited to: sine, square, and triangular. At low frequency (<1 Hz), the plated iron layers have high hardness and low ductility, while at high frequency (>100 Hz), the electroplated iron layers have low hardness and high ductility. The laminated structure with modulated hardness and ductility makes the material stronger than homogeneous material.

[0095] The electroplating system includes a tank, electrolyte of FeCl.sub.2 bath with or without CaCl.sub.2, computer controlled heater to maintain bath temperature at 60 C., a power supply that can generate wave forms of sine wave and square wave with DC offset, and a controlling computer. The anode is a low carbon steel sheet, and the cathode is a titanium plate which will make it easy for the deposit to be peeled off. Carbon steel can also be used as the cathode if the deposit does not need to be peeled off from the substrate. Polypropylene balls are used to cover the bath surface in order to reduce bath evaporation.

[0096] The process for producing an iron laminate is as follows:

[0097] 1. Prepare a tank of electrolyte consisting of 2.0 M FeCl.sub.2 or 1.7 M FeCl.sub.2 plus 1.7 CaCl.sub.2 in deionized water.

[0098] 2. Adjust the pH of the electrolyte to 0.5-1.5 by addition of HCl.

[0099] 3. Control the bath temperature at 60 C.

[0100] 4. Clean the titanium substrate cathode and low carbon steel sheet anode with deionized water and immerse both of them into the bath.

[0101] 5. To start electroplating a high ductility layer, turn on the power supply, and controlling the power supply to generate a sine wave having a beta of 1.26, by setting the following parameters: 10-1000 Hz with a peak current cathodic current density of 43 mA/cm.sup.2 and a peak anodic current density of 34 mA/cm.sup.2 applied to the substrate (i.e., a peak to peak current density of 78 mA/cm.sup.2 with a DC offset of 4.4 mA/cm.sup.2). Continue electroplating for an amount of time necessary to achieve the desired high ductility layer thickness.

[0102] 6. To continue electroplating a high hardness layer, change the power supply wave form (shifted sine wave having a beta of 1.26) using the computer, with the following parameters: 1 Hz with a peak current cathodic current density of 43 mA/cm.sup.2 and a peak anodic current density of 34 mA/cm.sup.2 applied to the substrate (i.e., a peak to peak current density of 78 mA/cm.sup.2 with a DC offset of 4.4 mA/cm.sup.2). Keep on electroplating for a specific amount of time which is determined by the desired high hardness layer thickness.

[0103] 7. Remove the substrate and deposit from the bath and immerse in deionized (DI) water for 10 minutes and blow it dry with compressed air.

[0104] 8. Peel the deposit from the underlying titanium substrate to yield a free-standing temperature modulated laminate.

Possible Substrates

[0105] In the examples described above the substrates used are in the form of a solid, conductive mandrel (i.e., titanium or stainless steel). While the substrate may comprise a solid, conductive material, other substrates are also possible. For example, instead of being solid, the substrate may be formed of a porous material, such as a consolidated porous substrate, such as a foam, a mesh, or a fabric. Alternatively, the substrate can be formed. of a unconsolidated material, such as, a bed of particles, or a plurality of unconnected fibers. In some embodiments, the substrate is formed from a conductive material or a non-conductive material which is made conductive by metallizing. In other embodiments, the substrate may be a semi-conductive material, such as a silicon wafer The substrate may be left in place after deposition of the NMCs or NGCs or may be removed.

Articles Utilizing NMCs or NGCs

[0106] Layered materials described herein can provide tailored material properties, which are advantageous in advance material applications. For example, the NMCs and NGCs described herein can be used in ballistic applications (e.g., body armor panels or tank panels), vehicle (auto, water, air) applications (e.g., car door panels, chassis components, and boat, plane and helicopter body parts) to provide a bulk material that is both light weight and structurally sound. In addition, NMCs and NGC can be used in sporting equipment applications (e.g., tennis racket frames, shafts), building applications (support beams, framing), transportation applications (e.g., transportation containers) and high temperature applications (e.g., engine and exhaust parts).