METHOD AND APPARATUS FOR INFILTRATION OF A MICRO/NANOFIBER FILM

Abstract

There is provided an apparatus and method for manufacturing of an infiltrated fiber-based composite film. The apparatus comprises two tool blocks arranged opposite each other enabling a fiber-based film to be arranged between the tool blocks. At least one of the tool blocks comprises a recess so that the recess can form a sealed cavity enclosing a portion of the film when the tool blocks are in contact with each other. At least one of the tool blocks comprises a vacuum channel connecting cavity to a vacuum pump for drawing a vacuum in the cavity; a melt channel connecting the cavity to a source of molten material. The melt channel comprises a valve arrangement controlling delivery of the molten material to the cavity; pressure means to achieve an elevated pressure onto the molten material within the cavity such that a fiber film in the cavity is infiltrated by the molten material; and an ejection piston for ejecting an infiltrated fiber film from the cavity.

Claims

1. An apparatus for manufacturing of an infiltrated fiber-based composite film, said apparatus comprising: two tool blocks (102a, 102b) arranged opposite each other enabling a fiber-based film (106) to be arranged between said tool blocks, wherein at least one of said tool blocks comprising a recess (104a, 104b); wherein at least one of said tool blocks is movable towards the opposing tool block such that said recess forms a sealed cavity configured to enclose a portion of said film when said tool blocks are in contact with each other; and wherein at least one of said tool blocks comprises: a vacuum channel (116) in a first end connected to said recess and in a second end connectable to a vacuum pump for drawing a vacuum in said cavity; a melt channel (110) in a first end connected to said recess and in a second end connected to a source of molten material (108); said melt channel comprising a valve arrangement configured to control delivery of said molten material to said cavity; a heater configured to heat said cavity to a temperature exceeding a melting temperature of said molten material; pressure means configured to achieve an elevated pressure within said cavity such that a fiber film in said cavity is infiltrated by said molten material; and an ejection piston (122) configured to eject an infiltrated fiber film from the cavity, when the tool blocks are in a retracted position spaced apart from each other.

2. The apparatus according to claim 1, wherein said recess has a depth in the range of 5 to 500 micrometers.

3. The apparatus according to claim 1, wherein said valve arrangement comprises: a channel valve (112) configured to control the delivery of molten material from said source to said melt channel; and an injector valve (114) configured to control the delivery of molten material from said melt channel (7) to said cavity.

4. The apparatus according to claim 1, wherein said pressure means are configured to provide a pressure within said cavity higher than 30 MPa

5. The apparatus according to claim 1, wherein said pressure means comprises an injector piston (116) connected to said melt channel such that said molten material is infiltrated at an elevated pressure into said film in said cavity by means of actuation of said injector piston.

6. (canceled)

7. The apparatus according to claim 1, wherein said tool block comprises cooling means configured to cool said cavity to a temperature lower than said meting temperature of said molten material.

8. The apparatus according to claim 6, wherein said cooling means comprises a cooling channel containing a fluidic cooling medium.

9. The apparatus according to claim 1, wherein each tool block comprises a recess, and wherein said tool blocks are arranged such that said recesses face each other.

10. (canceled)

11. (canceled)

12. An assembly for reel-to-reel manufacturing of an infiltrated fiber-based composite film, said assembly comprising: an apparatus according to claim 1; a micro/nanofiber film (12); a storage reel (8) holding said film; a collecting reel (9) configured to receive said film; wherein said film is arranged between said storage reel and said collecting reel such that a path of said film from said storage reel to said collecting reel runs between said tool blocks.

13. The assembly according to claim 12, wherein said micro/nanofiber film comprise fibers selected from the group comprising polyimide, polyurethane, nylon, polyimide, polyacrylonitrile, polyaramid, high density polyethylene, PEEK, Kevlar polyester, boron nitride, carbon fibers, carbon nanotubes, inorganic fibers and graphene coated fibers.

14. The assembly according to claim 13, wherein said film has a surface modified to facilitate wetting of the molten material to said film, wherein said surface modification compirses coating fibers of said film with Ag, Cu, Au, Ni, Pd, Ti and/or Pt or a combination thereof.

15. A method for reel-to-reel manufacturing of a micro/nanofiber-based film infiltrated with metal or metal alloy matrix material, said method comprising the steps of; arranging micro/nanofiber-based film between a storage reel holding said film and a collecting reel receiving said film; enclosing a portion of said film in a cavity formed by pressing together a first and a second tool block arranged opposite each other, wherein at least one of said tool blocks comprises a recess forming said cavity; providing a molten material to said cavity; elevating a pressure onto said molten material within said cavity such that a fiber film in said cavity is infiltrated by said molten material; and cooling said cavity to a temperature below a melting temperature of said molten material; and releasing said film by moving apart said tool blocks.

16. The method according to claim 15, wherein providing a molten material to said cavity comprises: opening a channel valve (112) to allow molten metal to flow from the source of molten material (108) into the melt channel (110); closing the channel valve; opening an injector valve (114) such that the molten metal flows into the cavity; closing the injector valve; and activating said injection piston (117) to push liquid melt into the cavity.

17. The apparatus according to claim 1, wherein the valve arrangement comprises an injection piston (117) arranged to push liquid melt into the tool insert cavity.

18. The apparatus according to claim 1, wherein the valve arrangement comprises a channel valve (112) configured to be opened to allow molten metal to flow from the source of molten material (108) into the melt channel (110).

19. The apparatus according to claim 1, wherein the valve arrangement comprises an injector valve (114) configured to be opened such that the molten metal flows into the cavity.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] These and other aspects of the present invention will now be described in more detail with reference to the appended drawings showing an example embodiment of the invention, wherein:

[0026] FIGS. 1a and 1b schematically illustrates an apparatus according to an embodiment of the invention; and

[0027] FIG. 2 is a flow chart outlining the general steps of a method according to an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0028] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person. Like reference characters refer to like elements throughout.

[0029] The invention relates to a process for making complete and uniform infiltration of a metal/alloy matrix material into films of continuous micro and/or nanofibers. More specifically, this invention relates to the process and tool for forming such composite in a reel-to-reel production.

[0030] FIG. 1 schematically illustrates an apparatus 100 for reel-to-reel manufacturing of an infiltrated micro/nanofiber film. The apparatus comprises a first tool block 102a and a second tool block 102b which are arranged opposite each other. Each tool block comprises a respective recess 104a, 104b so that the recesses form a cavity when the tool blocks are pressed together. A fiber-based composite film 106 is arranged between the tool blocks 102a, 102b and between the recesses 104a, 104b so that a portion of the film 106 is enclosed in the cavity when the two tool blocks 102a, 102b are pressed together. One of the tool blocks, here the second tool block 102b, comprises a delivery system for providing a molten material to the recess. A molten metal material is stored in a container 108 which is connected to a melt channel 110 of the tool block 102b. A channel valve 112 is arranged between the container 108 and the melt channel 110 to control the delivery of molten material to the melt channel. An injector valve 114 is arranged to control the delivery of molten material from the melt channel 110 to the cavity. The tool block 102b further comprises an injector piston 116 arranged in connection with the melt channel 110 and configured to inject the molten material into the cavity at an elevated pressure. The channel arrangement of the tool block 102b also comprises a vacuum channel 116 connecting a vacuum pump 118 to the cavity via a vacuum valve 120. An ejection piston 122 is arranged in the first tool block 102a for ejecting infiltrated portion of the film 106 from the recess 104a. The ejection piston 122 may also comprise cooling channels.

[0031] FIG. 1a further illustrates that the micro/nanofiber film 106 is arranged on a storage reel 124 holding the film. The film 106 runs between the tool blocks 104a, 104b to a collecting reel 126.

[0032] FIG. 1b illustrates the apparatus in a position where the two tool blocks 102a, 102b are pressed together so that the recesses 104a, 104b to form a cavity 150 in which a portion of the film 106 is enclosed.

[0033] FIG. 2 is a flow chart outlining the general steps of the manufacturing method for forming an infiltrated micro/nanofiber film. The method of FIG. 2 will be discussed with reference to FIGS. 1a-b.

The film that is infiltrated in the described process can comprise continuous micro and/or nanofibers made of a polymeric, boron nitride or carbon based composition. The film can be formed through, but not limited to, an electrospinning process, followed by additional processes such as nitration or carbonization. Typically the films have a porosity of 6020%, a total thickness of 5-200 m, and are made from fibers with diameters of 100 nm-15 m. The film can also have an additional layer such as a thin coating on the fibers to facilitate the wetting of the molten material, which can be formed through both dry and wet deposition techniques, such as CVD, sputtering, electroplating, and electroless plating. In an example embodiment the reel/spool/roller 124 is carrying a 30 meter long continuous film of continuous polyimide submicron fibers coated with Ag particles. Movement of the film from the storage reel 124 to the collecting reel is controlled by a motor.

[0034] In one embodiment, the tool blocks 102a-b are made from aluminum alloy, and incorporate electrical heating elements with several kW heating effect, channels for oil cooling, and with a geometry that allows an ejection piston. The tool blocks 102a-b comprises insert blocks 128a-b made from stainless steel, having polished surfaces and a cavity of a geometry that corresponds to the desired geometry of the final composite film. The tool blocks and tool inserts have channels connected to an injection piston 116 which can push liquid melt into the tool insert cavity with high pressure.

[0035] First 202, the tool blocks 102a-b closes around the film 106 with a sufficiently high locking force and the recesses 104a-b forms a cavity 150 which is sealed in part by the film itself and in which cavity a portion of the film is in a non-compressed state

[0036] Next, 204, the vacuum valve 120 is opened and the vacuum pump 118 is activated to draw vacuum in the cavity. The vacuum valve 120 is then closed.

[0037] After vacuum is formed in the cavity, heating elements heats 206 the tool blocks 102a, 102b and in particular the inserts 128a, 128b so that the temperature in the parts forming the cavity reaches a temperature of 247 C., which is 30 C. higher than the melting temperature of the metal to be used, in this example a SnAgCu alloy.

[0038] Next 208, the channel valve 112 is opened to allow molten metal to flow from the molten metal container 108 into the melt channel 110. The channel valve 112 is open until the melt channel 110 is filled. Filling of the melt channel may include retracting the injector piston 116 to facilitate additional filling of molten metal in the channel system. The melt channel 110 may also be fully or partially filled with a molten material from a previous cycle. The heating elements for heating the cavity are thus arranged to also ensure that the melt channel is sufficiently heated to enable a flow of molten material through the channel.

[0039] After delivery of molten metal to the melt channel 110, the injector valve 114 is opened so that the molten metal flows into the cavity 150, helped by the vacuum in the cavity 150, to fill 210 the cavity and to enclose the film. After filling of the cavity, the channel valve 112 is closed.

[0040] In the next step 212, a high pressure, typically above 30 MPa, is applied by the injection piston (116) to force infiltration of the melt metal/alloy matrix material into the pores of the film. The force applied on the injection piston is then reduced and the injector valve is closed.

[0041] After infiltration of the film, the tool blocks and inserts are cooled 214 down to a temperature of about 187 C., which is 30 degrees below the melting point of the SnAgCu alloy, by flowing oil in the cooling channels in the tool, the tool inserts and ejection piston 122.

[0042] Once the cavity and the film therein has reached the target temperatures, the tool blocks 104a-b are moved apart and the infiltrated portion of the film is ejected 216 by the ejection piston 122. After ejection of the film, the film may be moved a distance and a new film portion may be infiltrated by restarting the cycle.

[0043] Through the above described method consecutive portions of the film can be sequentially infiltrated in an efficient manner. If reel-to-reel production is undesirable, the apparatus 100 may equally well be used for infiltration of individual pieces of film.

[0044] Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. For example, the channels and valves may be arranged in a different manner, while still achieving the same effect as the above described apparatus. Also, it should be noted that other parts of the system may be omitted, interchanged or arranged in various ways, the apparatus yet being able to perform the functionality of the present invention.

[0045] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage.