Metal graphite composite bipolar plate and preparation method thereof

Abstract

The invention provides a metal graphite composite bipolar plate and a preparation method thereof, and solves the technical problems of complex manufacturing process, insufficient overall rigidity and the like in the prior art. The bipolar plate is provided with a graphite layer, a middle layer and a base layer, the bipolar plate is sequentially provided with the graphite layer, the middle layer and the base layer in a metallurgical connection mode from top to bottom, the graphite layer is flexible graphite paper, the middle layer is copper-nickel clad foil, the copper-nickel clad foil sequentially comprises a copper plate and a nickel plate from top to bottom, and the base layer is a titanium thin plate; the preparation method of the bipolar plate comprises the following steps: S1, pretreating flexible graphite paper; S2, cleaning the surfaces of a copper plate, a nickel plate and a titanium thin plate; s3, the flexible graphite paper pretreated in the step S1 and the copper plate, the nickel plate and the titanium thin plate subjected to surface cleaning treatment in the step S2 are stacked from top to bottom for compression molding, mold closing is kept and heated to 800-850 DEG C, the mold closing pressure is 5-10 MPa, and after the pressure is kept for a period of time, the metal graphite composite bipolar plate is obtained; the method can be widely applied to the technical field of fuel cell bipolar plate precision manufacturing.

Description

Technical Field

[0001] The present application relates to the technical field of precision manufacturing of bipolar plates for fuel cells, and in particular to a metal-graphite composite bipolar plate and a preparation method thereof. Background Art

[0002] With the development of hydrogen energy technology, fuel cells, as a clean energy technology, have received widespread attention and application. In the fuel cell system, the bipolar plate, as one of the core components, undertakes multiple functions such as electrical conductivity, heat conduction and gas distribution. The material properties of the bipolar plate directly affect the efficiency, life and cost of the fuel cell. The bipolar plate material needs to be corrosion-resistant, conductive, have good mechanical strength, be low-priced, and easy to batch process.

[0003] At present, commonly used bipolar plate materials mainly include graphite, metal and composite materials. Graphite bipolar plates are widely used in medium and low temperature fuel cells due to their excellent electrical conductivity, good corrosion resistance and high mechanical strength. The Chinese invention with publication number CN109755603 A discloses an ultra-thin metal sheet sandwich flexible graphite bipolar plate and its preparation method. By adding metal sheets to the raw materials of the flexible graphite plate, an ultra-thin flexible graphite hydrogen and oxygen plate is prepared by molding. While ensuring the performance of the original flexible graphite plate, the strength of the bipolar plate is improved and the thickness of the bipolar plate is reduced. However, this method still has the inherent problems of graphite bipolar plates such as complex manufacturing process and insufficient overall rigidity. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the above-mentioned technology, provide a metal-graphite composite bipolar plate and a preparation method thereof, simplify the manufacturing process, and improve the strength of the metal-graphite composite bipolar plate.

[0005] To this end, the present invention provides a metal-graphite composite bipolar plate, which is provided with a graphite layer, an intermediate layer and a base layer; the bipolar plate is provided with a graphite layer, an intermediate layer and a base layer metallurgically connected in sequence from top to bottom; wherein the graphite layer is flexible graphite paper; the intermediate layer is a copper-nickel composite foil, and the copper-nickel composite foil is copper plate and nickel plate in sequence from top to bottom; and the base layer is a titanium thin plate.

[0006] A method for preparing a metal-graphite composite bipolar plate as described above comprises the following steps:

[0007] Step S1. Pre-treating the flexible graphite paper for standby use;

[0008] Step S2. Clean the surfaces of the copper plate, nickel plate, and titanium plate for later use;

[0009] Step S3. The flexible graphite paper pretreated in step S1 and the copper plate, nickel plate and titanium sheet surface cleaned in step S2 are stacked from top to bottom for compression molding, the mold is kept closed and heated to 800-850°C, the mold pressure is 5-10MPa, and after maintaining the pressure for a period of time, a metal-graphite composite bipolar plate is obtained.

[0010] Preferably, in step S3, the forming device used is provided with an upper mold mechanism and a lower mold mechanism, the upper mold mechanism is provided with an upper mold base plate and an upper mold plate, and micro-protrusions are provided below the lower surface of the upper mold plate; the lower mold mechanism is provided with a lower mold base plate and a lower mold plate, and micro-grooves are provided on the upper surface of the lower base plate. The upper mold plate and the lower mold plate are arranged opposite to each other up and down, and after the mold is closed, the micro-protrusions and micro-grooves are matched to form a microchannel.

[0011] The forming device is also provided with a stepped punch mechanism, which is provided with a pad and multiple punch assemblies; each punch assembly is provided with a segmented punch, a pressure rod, a first spring, and a second spring; a micro-protrusion is provided at the lower part of the segmented punch, and a first blind hole opening upward is provided at the upper part of the segmented punch; a hole edge extending inward is provided at the opening of the first blind hole, and a first spring is installed in the first blind hole.

[0012] The upper template is provided with a plurality of longitudinal through holes spaced in sequence from left to right, and a punch assembly is installed corresponding to each longitudinal through hole; the segmented punch is arranged in the longitudinal through hole, and the two are slidably connected; the pad covers the longitudinal through hole, and the top end of the pressure rod is provided with a first stopper, and the rod body of the pressure rod passes downward through the second spring and the pad in turn and then enters the longitudinal through hole, and the bottom end of the pressure rod is provided with a second stopper, and the second stopper is connected to the first spring. Under the action of the elastic force of the first spring, the second stopper is movably engaged in the edge of the hole.

[0013] The lengths of the rods of the plurality of pressure rods exposed from the pad are distributed in a step-like manner from left to right.

[0014] The present invention provides a metal-graphite composite bipolar plate and a preparation method thereof, and the beneficial effects thereof are as follows:

[0015] (1) Copper-nickel composite foil is used as the intermediate layer to connect the flexible graphite paper and the substrate. Through high-temperature pressure treatment, metallurgical connections such as carbides and metal compounds are formed between the flexible graphite paper and the copper plate, and between the nickel plate and the titanium sheet, which significantly enhances the connection strength between the graphite paper and the metal substrate.

[0016] (2) Copper-nickel composite foil is used as the intermediate layer. The electrode potential of the copper layer is higher than that of the carbon electrode, which will hinder the occurrence of galvanic corrosion.

[0017] (3) When the cathode plate of the bipolar plate is in an oxygen-rich environment, copper is prone to oxidative corrosion. At this time, the protective layer formed by the nickel plate can effectively prevent the further expansion of corrosion and fully protect the substrate surface.

[0018] (5) The flexible graphite paper does not need to be bonded to the intermediate layer before forming, which reduces the risk of the flexible graphite paper breaking during the forming process. The preparation of the metal-graphite composite bipolar plate can be completed in one set of molds and one process, which reduces the preparation process and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 It is a cross-sectional structural diagram of the metal-graphite composite bipolar plate of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram of the structure of the enlarged view of part A shown;

[0022] Figure 3 It is a structural schematic diagram of a partial cross-sectional view of the compression molding device of the present invention in a mold opening state;

[0023] Figure 4 for Figure 3 A schematic structural diagram of an enlarged view of part B shown;

[0024] Figure 5 for Figure 3 The structural schematic diagram of the enlarged view of the C part shown;

[0025] Figure 6 It is a structural schematic diagram of a partial cross-sectional view of the compression molding device of the present invention in the first action during the mold closing process;

[0026] Figure 7 It is a structural schematic diagram of a partial cross-sectional view of the compression molding device of the present invention in the second action during the mold closing process;

[0027] Figure 8 It is a structural schematic diagram of a partial cross-sectional view of the compression molding device of the present invention in a mold closing state.

[0028] Markings in the figure: 1. upper die base plate, 2. upper template, 3. micro protrusion, 4. lower die base plate, 5. lower template, 6. micro groove, 7. pad, 8. punch assembly, 9. segmented punch, 10. pressure rod, 11. first spring, 12. second spring, 13. first blind hole, 14. hole edge, 15. longitudinal through hole, 16. first stopper, 17. second stopper, 18. first guide column, 19. limit support device, 20. limit support rod, 21. second blind hole, 22. third spring, 23. third stopper, 24. sheet workpiece, 25. flexible graphite paper, 26. copper-nickel composite foil, 27. titanium sheet, 261. copper plate, 262. nickel plate. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. The methods used in the present invention are conventional methods unless otherwise specified; the raw materials and devices used are conventional commercial products unless otherwise specified.

[0030] Example 1

[0031] Depend on Figure 1 , Figure 2 As shown, the present invention provides a metal-graphite composite bipolar plate, which is provided with a graphite layer, an intermediate layer and a base layer; it is characterized in that the bipolar plate is provided with a graphite layer, an intermediate layer and a base layer in sequence metallurgically connected from top to bottom; wherein the graphite layer is a flexible graphite paper 25; the intermediate layer is a copper-nickel composite foil 26, and the copper-nickel composite foil 26 is a copper plate 261 and a nickel plate 262 from top to bottom; and the base layer is a titanium thin plate 27.

[0032] On the one hand, copper-nickel composite foil 26 is used as an intermediate layer to connect the flexible graphite paper 25 and the substrate, and metallurgical connections such as carbides and metal compounds are formed between the flexible graphite paper 25 and the copper plate 261 as well as between the nickel plate 262 and the titanium thin plate 27, which significantly enhances the connection strength between the graphite paper and the metal substrate.

[0033] On the other hand, when the copper-nickel composite foil 26 is used as the intermediate layer, the electrode potential of the copper layer is higher than that of the carbon electrode, which will hinder the occurrence of galvanic corrosion.

[0034] Third, when the cathode plate of the bipolar plate is in an oxygen-rich environment, copper is prone to oxidation corrosion. At this time, the protective layer formed by the nickel plate 262 can effectively prevent the further expansion of corrosion and fully protect the surface of the substrate.

[0035] Fourth, there is no adhesive layer between the flexible graphite paper 25 and the middle layer in the prior art, which reduces the risk of rupture of the flexible graphite paper 25 during the forming process. For example, the prior art with publication number CN 110212212 A discloses a bipolar plate with a single-sided metal plate and graphite composite and a preparation method. After the flexible graphite paper 25 is bonded to the metal plate and then molded, it is easy to cause the flexible graphite paper 25 to rupture during the forming process, affecting its conductivity and corrosion resistance.

[0036] Preferably, the thickness of the flexible graphite paper 25 is 0.02-0.05 mm, the thickness of the copper-nickel composite foil 26 is 0.05-0.15 mm, and the thickness of the titanium sheet 27 is 0.08-0.1 mm. Compared with the prior art, the use of the extremely thin flexible graphite paper 25 and the extremely thin metal intermediate layer copper-nickel composite foil 26 only increases the thickness by 0.1-0.15 mm, greatly improves the corrosion resistance of the metal bipolar plate, avoids the coating of the conductive corrosion-resistant coating on the metal surface, and reduces the surface treatment cost of the metal bipolar plate.

[0037] Example 2

[0038] The present invention provides a method for preparing the metal-graphite composite bipolar plate described in Example 1, comprising the following steps:

[0039] Step S1. Pre-treating the flexible graphite paper 25 for standby use;

[0040] Step S2. Clean the surfaces of the copper plate 261, the nickel plate 262, and the titanium sheet 27 for later use;

[0041] Step S3. The flexible graphite paper 25 pretreated in step S1 and the copper plate 261, nickel plate 262 and titanium sheet 27 surface-cleaned in step S2 are stacked from top to bottom for compression molding, the mold is kept closed and heated to 800-850°C, and the mold pressure is 5-10 MPa to ensure sufficient contact between the flexible graphite paper 25 and the copper plate 261 as well as the titanium sheet 27 and the nickel plate 262. After maintaining the pressure for a period of time, a metal-graphite composite bipolar plate is obtained.

[0042] In the step S1, preferably, the pretreatment method of the flexible graphite paper 25 includes: vacuum immersing the flexible graphite paper 25 in the treatment liquid, and drying and curing after fully immersing; the treatment liquid is any one of phenolic resin, epoxy resin, and acrylate diluted with water to a viscosity of 300mPa.s to 600mPa.s. Further preferably, the flexible graphite paper 25 is immersed in a vacuum tank containing the treatment liquid and fully immersed at a vacuum degree of 133Pa; then the soaked flexible graphite paper 25 is placed in a drying furnace, and the curing is completed under the protection of an inert gas at the curing temperature of the treatment liquid. Among them, the curing temperature of the phenolic resin is 130 to 150°C, the curing temperature of the epoxy resin is 60 to 80°C, and the curing temperature of the acrylate is 60 to 80°C. The curing time is generally 2 hours, which can be adjusted according to actual conditions. Thereby solving the technical problem that the prior art uses resin bonding between the graphite paper and the bipolar plate, and the resin is not strong enough during the long-term operating temperature cycle of the fuel cell, and it is easy to fall off from the metal surface.

[0043] In step S2, preferably, the method for cleaning the surface of the copper plate 261 and the nickel plate 262 includes: respectively soaking the copper plate 261 and the nickel plate 262 in a 0.5-0.6 mol / L dilute hydrochloric acid solution, and applying ultrasonic vibration, and applying ultrasonic vibration at the same time. The soaking time is usually 10-20 minutes, which can be adjusted according to actual conditions.

[0044] In the step S2, preferably, the method for cleaning the surface of the titanium thin plate 27 includes: grinding the surface of the titanium thin plate 27, usually using sandpaper, 1000 mesh sandpaper can be used, or other mesh sandpaper can be used according to actual conditions; then placing it in a 6.0-6.5 mol / L dilute nitric acid solution for full immersion, while applying ultrasonic vibration. The immersion time is usually 10-20 minutes, which can be adjusted according to actual conditions.

[0045] The present invention provides a method for preparing the metal-graphite composite bipolar plate described in Example 1. On the one hand, the present invention uses a copper-nickel composite foil 26 as an intermediate layer to connect the flexible graphite paper 25 and the substrate, and forms metallurgical connections such as carbides and metal compounds between the flexible graphite paper 25 and the copper plate 261 and between the nickel plate 262 and the titanium thin plate 27 through high-temperature pressure treatment, thereby significantly enhancing the connection strength between the graphite paper and the metal substrate; on the other hand, the flexible graphite paper 25 does not need to be bonded to the intermediate layer before forming, thereby reducing the risk of the flexible graphite paper 25 breaking during the forming process, and the preparation of the metal-graphite composite bipolar plate can be completed in a set of molds and a single process, thereby reducing the preparation process and improving production efficiency.

[0046] Example 3

[0047] Depend on Figure 3 , Figure 4 As shown, the molding device used for preparing the metal-graphite composite bipolar plate described in Example 1, or the molding device used for molding in step S3 of Example 2, includes an upper mold mechanism and a lower mold mechanism, the upper mold mechanism is provided with an upper mold base plate 1 and an upper mold plate 2, and a micro-protrusion 3 is provided below the lower surface of the upper mold plate 2; the lower mold mechanism is provided with a lower mold base plate 4 and a lower mold plate 5, and a micro-groove 6 is provided on the upper surface of the lower base plate, the upper mold plate 2 and the lower mold plate 5 are arranged opposite to each other up and down, and after the mold is closed, the micro-protrusion 3 matches the micro-groove 6 to form a microchannel.

[0048] The forming device is also provided with a stepped punch mechanism, which is provided with a pad 7 and multiple punch assemblies 8; each punch assembly 8 is provided with a segmented punch 9, a pressure rod 10, a first spring 11, and a second spring 12. The lower part of the segmented punch 9 is provided with a micro-protrusion 3, and the upper part of the segmented punch 9 is provided with a first blind hole 13 opening upward, and the opening of the first blind hole 13 is provided with a hole edge 14 extending inward, and a first spring 11 is installed in the first blind hole 13.

[0049] The upper template 2 is provided with a plurality of longitudinal through holes 15 spaced apart from each other from left to right, and a punch assembly 8 is installed corresponding to each longitudinal through hole 15; the segmented punch 9 is arranged in the longitudinal through hole 15, and the two are slidably connected; the pad 7 covers the longitudinal through hole 15, and the top end of the pressure rod 10 is provided with a first stopper 16, and the rod body of the pressure rod 10 passes downward through the second spring 12 and the pad 7 and then enters the longitudinal through hole 15, and the bottom end of the pressure rod 10 is provided with a second stopper 17, and the second stopper 17 is connected to the first spring 11. Under the action of the elastic force of the first spring 11, the second stopper 17 is movably engaged in the hole edge 14.

[0050] The lengths of the rods of the plurality of pressure rods 10 exposed from the backing plate 7 are distributed in a step-like decreasing manner from left to right.

[0051] When the present invention is used, the upper die bottom plate 1 and the lower die bottom plate 4 are fixed on the hydraulic press respectively, wherein the upper die bottom plate 1 is fixedly connected to the cross beam of the hydraulic press, and the lower die bottom plate 4 is fixed on the base of the hydraulic press, and the downward pressure of the upper die bottom plate 1 is controlled by controlling the displacement of the cross beam of the hydraulic press; first, a sheet workpiece 24 to be formed is placed in the forming area on the lower template 5, and the sheet workpiece 24 is the metal-graphite composite sheet to be formed in Example 1.

[0052] The specific forming process is as follows: the hydraulic press is started, the upper die bottom plate 1 moves downward, first touching the first punch assembly 8 on the left, pushing the pressure rod 10 of the punch assembly 8 downward, so that the first spring 11 and the second spring 12 are compressed, driving the segment punch 9 to move downward, and the micro protrusion 3 at the bottom of the segment punch 9 matches the micro groove 6 located directly below it, forming a micro channel of the plate workpiece 24 located on the far left, as shown in FIG. Figure 3 , Figure 4 , Figure 6 shown.

[0053] As the upper die bottom plate 1 continues to move downward, it touches the second punch assembly 8 on the left side, compresses the second pressure rod 10 on the left side to move downward, compresses the first spring 11 and the second spring 12, drives the segment punch 9 to move downward, and makes the sheet workpiece 24 flow to the left side to form the second microchannel on the left side, as shown in FIG. Figure 6 , Figure 7 shown.

[0054] As the upper die bottom plate 1 continues to move downward, the divided punches 9 of the five male die assemblies 8 form the microchannels from left to right. Finally, the entire upper die plate 2 is driven to move downward to complete the final mold closing process, and then heated and pressurized to complete the preparation of the metal-graphite composite bipolar plate, such as Figure 8 shown.

[0055] During the whole process, the formation of the microchannel of the metal-graphite composite bipolar plate relies on the flow of the flexible graphite paper from the right to the left, rather than the overall stamping deformation of the existing technology, which effectively avoids the rupture of the flexible graphite paper and ensures that the flexible graphite paper is intact.

[0056] In some embodiments, Figure 4 As shown, the first spring 11 is preferably a force transmission spring that maintains a constant elastic force within a corresponding stroke.

[0057] In some embodiments, Figure 4 As shown, the second spring 12 is preferably a compression spring for resisting compression force or storing energy.

[0058] In some embodiments, Figure 3 As shown, the forming device is preferably also provided with a first guide column 18 for guiding and positioning, the two ends of the first guide column 18 are respectively connected to the upper mold base plate 1 and the lower mold base plate 4, and the first guide column 18 is respectively slidably connected through the upper mold base plate 1, the upper mold plate 2, and the lower mold plate 5.

[0059] In some embodiments, Figure 4 As shown, the longitudinal through hole 15 of the upper template 2 is preferably a square hole with good stability.

[0060] In some embodiments, Figure 3 , Figure 5As shown, the forming device is preferably further provided with a limit support device 19, the support device is provided with a limit support rod 20, the lower surface of the upper template 2 is provided with a second blind hole 21 opening downward, a third spring 22 is installed in the second blind hole 21, the bottom end of the limit support rod 20 is installed on the lower template 5, and the top end of the limit support rod 20 is connected to the third spring 22. When the forming device is molded, the third spring 22 is compressed, the top end of the limit support rod 20 gradually enters the second blind hole 21, the third spring 22 is continuously compressed, and the mold is finally closed; when the forming device is molded, the elastic force of the third spring 22 is released, pushing the upper template 2 to rise, so that the upper template 2 and the lower template 5 are separated.

[0061] In some embodiments, preferably, a third stopper 23 is provided at the top end of the limiting support rod 20, the third stopper 23 is connected to the third spring 22, and the third stopper 23 is slidably connected to the inner wall of the second blind hole 21, so that the upper template 2 can rise or fall more stably and reliably.

[0062] In some embodiments, the third spring 22 is preferably a limit spring, which uses the elasticity of the spring to limit the range of the moving part.

[0063] It should be noted that:

[0064] (1) During the process of opening or closing the mold of the hydraulic press, under the action of the spring force of the first spring 11 and the second spring 12, the punch assembly 8 rises or falls in the longitudinal through hole 15; intuitively, the pressure rod 10 drives the segment punch 9 to rise or fall.

[0065] (2) During the mold opening process after the hydraulic press mold closing, the working state of the present invention is as follows Figure 8 , Figure 7 , Figure 6 , Figure 3 order.

[0066] (3) By Figure 3 As shown, the lengths of the rods of the plurality of pressure rods 10 exposed from the pad 7 are distributed in a stepped descending manner from left to right, preferably in an arithmetic progression, and the lengths of the rods of two adjacent pressure rods 10 exposed from the pad 7 differ by the height of the microchannel. The operator can adjust the length of the pressure rod 10 according to actual conditions.

[0067] In the description of the present invention, it is necessary to understand that the terms "left", "right", "up", "down", "top", "bottom", "front", "back", "inside", "outside", "back", "middle", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0068] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A metal-graphite composite bipolar plate, the bipolar plate comprising a graphite layer, an intermediate layer and a base layer; characterized in that: The bipolar plate is provided with the graphite layer, the intermediate layer, and the base layer metallurgically connected in sequence from top to bottom; wherein the graphite layer is a flexible graphite paper (25); the intermediate layer is a copper-nickel composite foil (26); the copper-nickel composite foil (26) is a copper plate (261) and a nickel plate (262) in sequence from top to bottom; and the base layer is a titanium thin plate (27).

2. The metal-graphite composite bipolar plate according to claim 1, characterized in that: The thickness of the flexible graphite paper (25) is 0.02-0.05 mm, the thickness of the copper-nickel composite foil (26) is 0.05-0.15 mm, and the thickness of the titanium thin plate (27) is 0.08-0.1 mm.

3. A method for preparing a metal-graphite composite bipolar plate as claimed in claim 1 or 2, characterized in that: The steps include: Step S1. pre-treating the flexible graphite paper (25) for standby use; Step S2. Clean the surfaces of the copper plate (261), the nickel plate (262), and the titanium sheet (27) for later use; Step S3. The flexible graphite paper (25) pretreated in step S1 and the copper plate (261), nickel plate (262) and titanium sheet (27) surface-cleaned in step S2 are stacked from top to bottom for compression molding, the molds are kept closed and heated to 800-850° C., the mold pressure is 5-10 MPa, and after maintaining the pressure for a period of time, the metal-graphite composite bipolar plate is obtained.

4. The method according to claim 3, characterized in that In the step S1, the pretreatment method of the flexible graphite paper (25) comprises: vacuum immersing the flexible graphite paper (25) in a treatment liquid, and drying and curing the treated liquid after being fully immersed; the treatment liquid is any one of phenolic resin, epoxy resin, and acrylate, which is diluted with water to a viscosity of 300mPa.s to 600mPa.s.

5. The method according to claim 4, characterized in that The flexible graphite paper (25) is immersed in a vacuum tank containing the treatment liquid and fully immersed at a vacuum degree of 133 Pa; then the immersed flexible graphite paper (25) is placed in a drying furnace and cured at the curing temperature of the treatment liquid under the protection of an inert gas.

6. The method according to claim 3, characterized in that: In the step S2, the method for cleaning the surface of the copper plate (261) and the nickel plate (262) comprises: adding the copper plate (261) and the nickel plate (262) into a 0.5-0.6 mol / L dilute hydrochloric acid solution to fully immerse them, and applying ultrasonic vibration, and applying ultrasonic vibration at the same time.

7. The method according to claim 3, characterized in that In the step S2, the method for cleaning the surface of the titanium thin plate (27) comprises: grinding the surface of the titanium thin plate (27), and then fully immersing it in a 6.0-6.5 mol / L dilute nitric acid solution while applying ultrasonic vibration.

8. The method according to claim 3, characterized in that In the step S3, the forming device used is provided with an upper mold mechanism and a lower mold mechanism, the upper mold mechanism is provided with an upper mold base plate (1) and an upper mold plate (2), and a micro protrusion (3) is provided below the lower surface of the upper mold plate (2); the lower mold mechanism is provided with a lower mold base plate (4) and a lower mold plate (5), and a micro groove (6) is provided on the upper surface of the lower mold base plate, and the upper mold plate (2) and the lower mold plate (5) are arranged opposite to each other in the upper and lower directions, and after the molds are closed, the micro protrusion (3) and the micro groove (6) are matched to form a micro channel; The forming device is also provided with a stepped punch mechanism, the stepped punch mechanism is provided with a pad (7) and a plurality of punch assemblies (8); each of the punch assemblies (8) is provided with a segmented punch (9), a pressure rod (10), a first spring (11), and a second spring (12); a micro protrusion (3) is provided at the lower part of the segmented punch (9); a first blind hole (13) opening upward is provided at the upper part of the segmented punch (9); a hole edge (14) extending inward is provided at the opening of the first blind hole (13); and a first spring (11) is installed in the first blind hole (13); The upper template (2) is provided with a plurality of longitudinal through holes (15) spaced from left to right, and each longitudinal through hole (15) is provided with a corresponding punch assembly (8); the segmented punch (9) is arranged in the longitudinal through hole (15), and the two are slidably connected; the pad (7) covers the longitudinal through hole (15), and the top end of the pressure rod (10) is provided with a first stopper (16), and the rod body of the pressure rod (10) passes through the second spring (12) and the pad (7) downwards and then enters the longitudinal through hole (15), and the bottom end of the pressure rod (10) is provided with a second stopper (17), and the second stopper (17) is connected to the first spring (11), and under the action of the elastic force of the first spring (11), the second stopper (17) is movably engaged in the hole edge (14); The lengths of the rod bodies of the plurality of pressure rods (10) exposed from the pad (7) are distributed in a step-like decreasing manner from left to right.

9. The method according to claim 8, characterized in that The first spring (11) is a force transmission spring, and the second spring (12) is a compression spring.

10. The method according to claim 8, characterized in that The forming device is also provided with a limit support device (19), the support device is provided with a limit support rod (20), the lower surface of the upper template (2) is provided with a second blind hole (21) opening downward, a third spring (22) is installed in the second blind hole (21), the bottom end of the limit support rod (20) is installed on the lower template (5), and the top end of the limit support rod (20) is connected to the third spring (22).

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