Gas diffusion layer production process with controllable porosity

Abstract

The invention belongs to the technical field of gas diffusion layer production, and mainly relates to a porosity-controllable gas diffusion layer production process which comprises the following steps: pretreating a plurality of titanium mesh rolls; the titanium mesh rolls are arranged in a laminated mode and fixed together through a pre-positioning device, so that a continuous multi-layer titanium mesh structure is formed, and then SPS low-temperature pre-pressing sintering is conducted; blanking a plurality of layers of titanium meshes into titanium mesh blanks, smearing solder resist, and then stacking the titanium mesh blanks; the titanium mesh blank is continuously conveyed into a continuous furnace to be welded, and a gas diffusion layer is obtained; and post-processing the welded gas diffusion layer, scanning to detect the thickness of the gas diffusion layer, and finally packaging. The multi-layer titanium mesh roll is firstly stacked to form a multi-layer structure, the multi-layer structure is blanked into a plurality of layers, then the multi-layer structure is stacked again, then the titanium mesh blank is continuously conveyed into the continuous furnace, the titanium mesh blank is welded in the continuous furnace, and a large amount of production time is saved, so that the production efficiency of the gas diffusion layer can be improved, and the rate of finished products is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of gas diffusion layer production, and mainly relates to a production process of a gas diffusion layer with controllable porosity. Background Art

[0002] How to achieve good gas-liquid transmission capacity of the gas diffusion layer and improve the conversion efficiency is the focus of current researchers. Existing studies have shown that the porosity of the gas diffusion layer can be regulated and the performance of the gas diffusion layer can be improved by multi-layer composite methods. For example, the patent application document with publication number CN113957470A proposes a method for preparing a porous diffusion layer, that is, first sintering a single-layer titanium plate with different pores by powder, and finally laminating and composite sintering to control the porosity. The patent application document with publication number CN118345393A increases the porosity of the titanium felt by sequentially connecting a fiber titanium felt layer and a multi-layer titanium mesh layer for composite sintering.

[0003] Among them, the patent application document with publication number CN113957470A discloses a porous diffusion layer and a preparation method thereof and a proton exchange membrane water electrolysis hydrogen production device, wherein the porous diffusion layer includes at least two sub-diffusion layers stacked and arranged, namely, a first sub-diffusion layer, a second sub-diffusion layer, and ... an Nth sub-diffusion layer. However, the method for preparing the porous diffusion layer disclosed in the patent mentions that the first sub-diffusion layer is formed by sintering once, the second sub-diffusion layer is formed on the surface of the first sub-diffusion layer by sintering or spraying, and other sub-diffusion layers are formed in the same way, and multiple sub-diffusion layers are compositely sintered. This method of multiple step-by-step sintering is inefficient and does not meet the development needs of modern society. Summary of the invention

[0004] The invention provides a production process of a gas diffusion layer with controllable porosity, so as to solve the problem of low production efficiency of the gas diffusion layer in the prior art.

[0005] To solve the above problems, the present invention adopts the following technical solutions: A process for producing a gas diffusion layer with controllable porosity comprises the following steps: Step 1: preparing a plurality of titanium mesh rolls and pre-treating the titanium mesh rolls; Step 2: Lay multiple pre-treated titanium mesh rolls in layers and fix them together through a pre-positioning device to form a continuous multi-layer titanium mesh structure, and then perform SPS low-temperature pre-pressing and sintering; Step 3: Punch the continuous multi-layer titanium mesh after SPS low-temperature pre-pressing and sintering into fixed sizes to obtain a titanium mesh blank, then stack them, and apply solder resist on the titanium mesh blank; Step 4: The stacked titanium mesh blanks are continuously transported to a continuous furnace for vacuum heating, diffusion welding and post-weld cooling to obtain a gas diffusion layer; Step 5: Post-process the welded gas diffusion layer, scan and detect its thickness, and finally package it.

[0006] The method has the following beneficial effects: firstly, a plurality of titanium mesh rolls are stacked to form a multi-layer titanium mesh structure, and then a punching device is used to punch out titanium mesh blanks, and then the titanium mesh blanks are stacked again, a solder resist should be applied on the titanium mesh blanks, and then the stacked plurality of titanium mesh blanks are continuously conveyed to a continuous furnace, and welding is performed between two adjacent titanium meshes in each titanium mesh blank in the continuous furnace; compared with an ordinary welding furnace, the continuous furnace increases the number of titanium mesh blanks processed per unit time, and saves a lot of production time, so the production efficiency of the gas diffusion layer can be improved, and the yield rate can also be improved.

[0007] Furthermore, the pretreatment in step 1 is to clean the multiple titanium mesh rolls and then dry them.

[0008] The method has the following beneficial effects: there are multiple impurities on the titanium mesh roll, and after the titanium mesh roll is cleaned, the sintering quality can be improved.

[0009] Furthermore, the cleaning of the plurality of titanium mesh rolls is carried out by sequentially conveying the plurality of titanium mesh rolls to a cleaning tank containing different solutions through a transmission device, and the oil stains and oxide layers on the surface of the titanium mesh rolls are cleaned in an assembly line manner.

[0010] It has the following beneficial effects: the raw material is a titanium mesh roll processed into a specific shape, which passes through a transmission device such as a conveyor and enters a cleaning tank of different solutions in sequence, and the oil and oxide layer on the surface of the titanium mesh roll are cleaned in an assembly line manner, which reduces labor costs, saves time, and reduces some unnecessary collision losses during the turnover process; The use of assembly line operations has greatly improved product production efficiency, and the cleaning process is stable, ensuring the high quality of the subsequent welding process.

[0011] Furthermore, the pre-positioning device in step 2 uses a guide roller corresponding to each titanium mesh roll to guide the corresponding titanium mesh roll to one place, and presses multiple titanium meshes together through relatively arranged pressing rollers, and then performs SPS low-temperature pre-pressing and sintering.

[0012] The following beneficial effects are achieved: after SPS low-temperature pre-pressing and sintering, a multi-layer titanium mesh with uniform thickness can be obtained; SPS low-temperature pre-pressing and sintering does not use the heat conduction of the heating element to perform preliminary welding on the titanium mesh, but uses the discharge plasma generated instantly when the DC pulse current is passed through the electrode to make the multi-layer titanium mesh evenly generate Joule heat by itself, and performs preliminary welding by the self-heating effect inside the titanium mesh, and through a complete set of electrical-hydraulic control systems, the working pressure, stroke and speed can be accurately controlled; The temperature is measured by thermocouples or infrared thermometers to meet the high-precision displacement, pressure and temperature control required for pre-welding, which improves the quality of pre-welding and ensures the consistent deformation of the titanium mesh gas diffusion layer. This preliminary welding is efficient and low-cost.

[0013] Furthermore, the mesh holes in adjacent titanium meshes are stacked in an alternating manner.

[0014] The invention has the following beneficial effects: the size of the pores can be effectively controlled, so that a gas diffusion layer meeting the use requirements can be obtained.

[0015] Furthermore, the mesh holes of the plurality of titanium meshes are all diamond-shaped holes, and the diamond-shaped holes are stacked and staggered at 90 degrees.

[0016] Furthermore, the titanium mesh blanks punched out in step three are stacked in corresponding tooling to isolate two adjacent titanium mesh blanks, solder resist should be applied on the titanium mesh blanks, and then the tooling containing the stacked titanium mesh blanks is sent into the continuous furnace.

[0017] Furthermore, the tooling in step four is conveyed to a continuous furnace by a conveyor. The continuous furnace has a heating section, a welding section and a cooling section. The stacked titanium mesh blanks are successively vacuum heated in the heating section, diffusion welded in the welding section, and post-weld cooled in the cooling section. After cooling to room temperature, the welding is completed.

[0018] The method has the following beneficial effects: Step 4 is continuous vacuum diffusion welding, which is divided into three stages: vacuum heating, diffusion welding, and post-weld cooling. In this process, the residual contamination on the titanium mesh blank is removed, the welding rate of the titanium mesh blank is ensured, and the yield rate of the gas diffusion layer is improved; the continuous vacuum diffusion welding ensures product quality, reduces the time of manual operation and product transfer, improves efficiency, and reduces production costs; The continuous vacuum diffusion welding furnace (continuous furnace) is divided into three areas. The vacuum heating area and the welding area are kept in a high temperature state for a long time, which can quickly heat the product. After the secondary welding is completed, it enters the cooling area for rapid cooling. The various stages do not interfere with each other and can be carried out simultaneously, greatly improving efficiency.

[0019] Furthermore, the post-processing process in step five is to clean the welded titanium mesh blank after welding and then dry it.

[0020] Furthermore, when the thickness of the welded gas diffusion layer is detected, multiple points are taken on the gas diffusion layer, and detection probes are arranged above the points. Data from the multiple points are collected to quickly feed back the thickness of the gas diffusion layer.

[0021] The invention has the following beneficial effects: it adopts a fully automated multi-point detection method, avoids data errors caused by human operation, and contributes to product standardization; the detection principle adopts a mechanical contact measurement method, the gas diffusion layer is placed on the lower measuring surface, and the detection probe on the upper measuring surface parallel to the lower measuring surface falls onto the surface of the gas diffusion layer with a certain pressure, and the detection probe automatically measures the distance between the upper and lower surfaces, that is, the thickness of the gas diffusion layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] By reading the following detailed description with reference to the accompanying drawings, the above and other objects, features and advantages of the exemplary embodiments of the present invention will become readily understood. In the accompanying drawings, several embodiments of the present invention are shown in an exemplary and non-limiting manner, and the same or corresponding reference numerals represent the same or corresponding parts, wherein: Figure 1 The process flow of the present invention; Figure 2 It is a schematic diagram of the cleaning process; Figure 3 This is a schematic diagram of the SPS low-temperature pre-pressing sintering process; Figure 4 It is a schematic diagram of the continuous vacuum diffusion welding process; Figure 5 Schematic diagram of the scanning detection process.

[0023] Description of reference numerals: 1. Titanium mesh roll; 2. Cleaning tank; 3. SPS low-temperature pre-pressing and sintering device; 4. Punching equipment; 5. Continuous vacuum diffusion welding furnace; 6. Tooling; 7. Gas diffusion layer; 8. Lower measuring surface; 9. Detection probe; 10. Upper measuring surface; 11. Guide roller; 12. Pressing roller; 13. Titanium mesh blank. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Those skilled in the art should know that the embodiments described below are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0025] Various non-limiting embodiments of the present invention are described in detail below. Any number of elements in the accompanying drawings is for illustration and not for limitation, and any naming is only for distinction and does not have any limiting meaning. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0026] This embodiment proposes a production process for a gas diffusion layer with controllable porosity, which adopts automated cleaning technology to improve efficiency, SPS low-temperature pre-pressing sintering and continuous vacuum diffusion welding to improve the connection quality and thickness uniformity of the gas diffusion layer 7, and finally uses a fully automated detection probe 9 to detect thickness reliability. This method can greatly improve product quality and production efficiency.

[0027] like Figure 1 As shown, a process for producing a gas diffusion layer with controllable porosity specifically comprises the following steps: Step 1: If Figure 1 , Figure 2 As shown, a plurality of titanium mesh rolls 1 are prepared and pre-treated. The pre-treatment is to clean the plurality of titanium mesh rolls 1 and then dry them. The plurality of titanium mesh rolls 1 are cleaned using different cleaning solutions in sequence to clean different impurities on the surface of the titanium mesh rolls 1.

[0028] The raw material titanium mesh roll 1 has a specific shape. The titanium mesh roll 1 passes through a transmission device such as a conveyor and enters a cleaning tank 2 of different solutions in sequence. The oil stains and oxide layers on the surface of the titanium mesh roll 1 are cleaned in an assembly line manner, which reduces labor costs, saves time, and reduces some unnecessary bump losses during the turnover process.

[0029] In this embodiment, there are at least two cleaning tanks 2 , each of which has a different solution, and is used to treat the oil stains and the oxide layer on the surface of the titanium mesh roll 1 , respectively.

[0030] The solution used for removing oil stains in this embodiment may be a solution containing a surfactant; the solution used for removing the oxide layer may be a solution containing an acid.

[0031] In other embodiments, at least four cleaning tanks 2, in addition to the cleaning tanks 2 for treating the oil stains and oxide layers on the surface of the titanium mesh roll 1, can also add two cleaning tanks 2 containing deionized water, which are placed after the first two cleaning tanks 2, that is, the titanium mesh roll 1 passes through the cleaning tank 2 for removing oil stains, the cleaning tank 2 containing deionized water, the cleaning tank 2 for removing oxide layers, and the cleaning tank 2 containing deionized water in sequence. In this way, after the oil stains and the curing layer are removed, they are removed with deionized water to prevent the solution in the previous cleaning tank 2 from entering the next cleaning tank 2.

[0032] The existing multi-layer gas diffusion layer 7 processing technology requires the raw material titanium mesh roll 1 to be cut into a specific shape and flattened before welding, and then the surface cleaning work is performed. The process and steps are cumbersome, and the workpiece needs to be continuously transported and circulated, which greatly wastes manpower and material resources. The processing technology proposed in this embodiment directly cleans the raw materials and operates on an assembly line, which greatly improves the product production efficiency, and the cleaning process is stable, ensuring the high quality of the subsequent welding process.

[0033] Step 2: If Figure 3 As shown, multiple pre-treated titanium mesh rolls 1 are stacked and fixed together by a pre-positioning device to form a continuous multi-layer titanium mesh structure, which is then subjected to SPS low-temperature pre-pressing and sintering. The pre-positioning device uses a guide roller 11 corresponding to each titanium mesh roll to guide the corresponding titanium mesh roll to one place, and then presses the multiple titanium meshes together through relatively arranged pressure rollers 12, and then performs SPS low-temperature pre-pressing and sintering. After SPS low-temperature pre-pressing and sintering, a multi-layer titanium mesh with uniform thickness can be obtained. The mesh holes in adjacent titanium meshes are staggered and stacked. And the mesh holes of multiple titanium meshes are all diamond holes, and the diamond holes are staggered and stacked at 90°.

[0034] The existing multi-layer gas diffusion layer 7 welding technology uses titanium powder or titanium fiber as raw materials, which are sintered layer by layer and then composite sintered to form. The process is complicated, costly, and time-consuming, which is not conducive to mass production. The multi-layer titanium mesh roll 1 for the gas diffusion layer 7 proposed in this embodiment is simple to prepare, low in cost, and the porosity can be controlled by lamination to ensure the subsequent product effect.

[0035] At the same time, in order to simplify the process and optimize the connection effect, an SPS low-temperature pre-pressing sintering device 3 is used to pre-weld the multi-layer titanium mesh at a relatively low temperature by utilizing the Joule heat effect and electric field effect generated by a strong DC pulse current to ensure uniform thickness of the product.

[0036] The heating method of the SPS low-temperature pre-pressing sintering device 3 does not use the heat conduction of the heating body to perform preliminary welding on the titanium mesh, but uses the discharge plasma instantly generated when the DC pulse current is passed through the electrode to make the multi-layer titanium mesh evenly generate Joule heat by itself, and the preliminary welding is performed by the self-heating effect of the titanium mesh. That is, when the discharge plasma appears in the gap or at the contact point between materials, a local high temperature state (discharge column) of tens to tens of thousands of degrees Celsius is instantly generated. This evaporates and melts on the surface of the material during the SPS low-temperature pre-pressing sintering process, and forms a "neck" around the contact area between the material particles, that is, a connection is generated.

[0037] The SPS low temperature pre-pressing sintering device 3 can accurately control the working pressure, stroke and speed through a complete set of electrical-hydraulic control systems.

[0038] The temperature is measured by thermocouples or infrared thermometers to meet the high-precision displacement, pressure and temperature control required for pre-welding, which improves the quality of pre-welding and ensures consistent deformation of multi-layer titanium mesh. This preliminary welding is efficient and low-cost.

[0039] In other embodiments, a hot rolling device may be used to replace the SPS low-temperature pre-pressing and sintering device 3 .

[0040] Step 3: Use the punching device 4 to punch the pre-pressed continuous multi-layer titanium mesh into a fixed size to obtain a titanium mesh blank 13. The punched titanium mesh blank 13 is stacked in the corresponding tooling 6. A solder resist should be applied to the titanium mesh blank 13 to prevent the titanium mesh blank 13 from being welded to the tooling 6 during welding. Then, the tooling 6 is sent to the continuous furnace. The welding in this embodiment occurs between adjacent titanium meshes in each titanium mesh blank 13, rather than between the titanium mesh blank 13 and the tooling 6.

[0041] In this embodiment, the tooling 6 is equipped with a plurality of titanium mesh blanks 13, and these titanium mesh blanks 13 are stacked, and the tooling 6 can isolate adjacent titanium mesh blanks 13. That is, the tooling 6 has a plurality of mutually isolated areas, and the titanium mesh blanks 13 are placed in the areas. The solder resist is applied on the titanium mesh blanks 13 to prevent the titanium mesh blanks 13 from being connected to the tooling 6 during welding.

[0042] Step 4: If Figure 4 As shown, the stacked titanium mesh blanks 13 need to be subjected to continuous vacuum diffusion welding, and multiple stacked titanium mesh blanks 13 are continuously transported to a continuous furnace for vacuum heating, diffusion welding and post-welding cooling in sequence. The stacked titanium mesh blanks 13 are in a tooling 6, and the tooling 6 is transported to the continuous furnace by a conveyor. The continuous furnace has a heating section, a welding section and a cooling section. The stacked titanium mesh blanks 13 are vacuum heated in the heating section, diffusion welded in the welding section, and post-welding cooled in the cooling section. After cooling to room temperature, the welding is completed to obtain a gas diffusion layer 7.

[0043] Continuous vacuum diffusion welding is divided into three stages: vacuum heating, diffusion welding and post-weld cooling. In this process, the residual contamination on the titanium mesh blank 13 is removed, the welding rate of the titanium mesh blank 13 is ensured, and the yield rate of the gas diffusion layer 7 is improved; continuous vacuum diffusion welding ensures product quality, reduces manual operation and product transfer time, improves efficiency, and reduces production costs.

[0044] Compared with the existing diffusion welding technology, the continuous vacuum diffusion welding furnace 5 (continuous furnace) is divided into three areas. The vacuum heating area and the welding area are kept in a high temperature state for a long time, which can quickly heat the product. After the secondary welding is completed, it enters the cooling area for rapid cooling. The various stages do not interfere with each other and can be carried out simultaneously, which greatly improves efficiency.

[0045] Step 5: Post-process the gas diffusion layer 7, then scan and detect its thickness, and finally package. The post-processing process mentioned here is to clean the welded gas diffusion layer 7 after welding and then dry it.

[0046] like Figure 5As shown, when the thickness of the welded gas diffusion layer 7 is detected, multiple points are taken on the gas diffusion layer 7, and detection probes 9 are arranged above the points. Data from multiple points are collected to quickly feedback the thickness of the gas diffusion layer 7, and packaging is performed after the detection is completed.

[0047] The use of a fully automated multi-point detection method avoids data errors caused by human operation and is conducive to product standardization. The detection principle adopts a mechanical contact measurement method, where the gas diffusion layer 7 is placed on the lower measuring surface 8, and the detection probe 9 on the upper measuring surface 10 parallel to the lower measuring surface 8 falls onto the surface of the gas diffusion layer 7 with a certain pressure. The detection probe 9 automatically measures the distance between the upper and lower surfaces, that is, the thickness of the gas diffusion layer 7.

[0048] First, multiple titanium mesh rolls 1 are stacked to form a multi-layer titanium mesh structure, and then the blanking device 4 is used to punch out the titanium mesh blank 13, and the titanium mesh blank 13 is stacked in the tooling 6 again. The titanium mesh blank 13 should be coated with a solder resist to prevent the titanium mesh blank 13 from being welded to the tooling 6, and then the stacked multiple titanium mesh blanks 13 are continuously transported to the continuous furnace, and the adjacent two titanium meshes in each titanium mesh blank 13 are welded in the continuous furnace. Compared with the ordinary welding furnace, the continuous furnace increases the number of titanium mesh blanks 13 processed per unit time, saving a lot of production time, so the production efficiency of the gas diffusion layer 7 can be improved, and the yield rate can also be improved.

[0049] The process described in this embodiment is suitable for continuous industrial production of the gas diffusion layer 7, can improve welding quality and yield rate, and is very helpful in increasing production capacity and reducing labor costs.

[0050] This embodiment provides a production process for the gas diffusion layer 7 for hydrogen production by electrolysis of water, aiming to provide technical ideas and process options for the problems of low welding rate, low overall connection strength, poor thickness uniformity, and low production efficiency in the existing technical solutions.

Claims

1. A process for producing a gas diffusion layer with controllable porosity, characterized in that: The following steps are involved: Step 1: preparing a plurality of titanium mesh rolls and pre-treating the titanium mesh rolls; Step 2: Lay multiple pre-treated titanium mesh rolls in layers and fix them together through a pre-positioning device to form a continuous multi-layer titanium mesh structure, and then perform SPS low-temperature pre-pressing and sintering; Step 3: Punch the continuous multi-layer titanium mesh after SPS low-temperature pre-pressing and sintering into fixed sizes to obtain a titanium mesh blank, then stack them, and apply solder resist on the titanium mesh blank; Step 4: The stacked titanium mesh blanks are continuously transported to a continuous furnace for vacuum heating, diffusion welding and post-weld cooling to obtain a gas diffusion layer; Step 5: Post-process the welded gas diffusion layer, scan and detect its thickness, and finally package it.

2. A process for producing a gas diffusion layer with controllable porosity according to claim 1, characterized in that: The pretreatment in step 1 is to clean a plurality of titanium mesh rolls and then dry them.

3. A process for producing a gas diffusion layer with controllable porosity according to claim 2, characterized in that: The cleaning of multiple titanium mesh rolls is carried out by sequentially conveying the multiple titanium mesh rolls to a cleaning tank containing different solutions through a transmission device, and the oil stains and oxide layers on the surface of the titanium mesh rolls are cleaned in an assembly line manner.

4. A process for producing a gas diffusion layer with controllable porosity according to claim 1, characterized in that: The pre-positioning device in step 2 uses a guide roller corresponding to each titanium mesh roll to guide the corresponding titanium mesh roll to one place, and presses multiple titanium meshes together through relatively arranged pressing rollers, and then performs SPS low-temperature pre-pressing sintering.

5. A process for producing a gas diffusion layer with controllable porosity according to claim 4, characterized in that: The mesh holes in adjacent titanium meshes are stacked in an alternating manner.

6. A process for producing a gas diffusion layer with controllable porosity according to claim 5, characterized in that: The mesh holes of the multiple titanium meshes are all diamond-shaped holes, and the diamond-shaped holes are stacked and staggered at 90 degrees.

7. A process for producing a gas diffusion layer with controllable porosity according to claim 1, characterized in that: The punched titanium mesh blanks in step 3 are stacked in corresponding tooling to isolate two adjacent titanium mesh blanks. Solder resist should be applied on the titanium mesh blanks, and then the tooling containing the stacked titanium mesh blanks is sent into the continuous furnace.

8. A process for producing a gas diffusion layer with controllable porosity according to claim 7, characterized in that: In step 4, the tooling is conveyed to a continuous furnace by a conveyor. The continuous furnace has a heating section, a welding section and a cooling section. The stacked titanium mesh blanks are vacuum heated in the heating section, diffusion welded in the welding section, and post-weld cooled in the cooling section. After cooling to room temperature, the welding is completed.

9. A process for producing a gas diffusion layer with controllable porosity according to claim 1, characterized in that: The post-processing process in step five is to clean the welded titanium mesh blank after welding and then dry it to obtain a gas diffusion layer.

10. A process for producing a gas diffusion layer with controllable porosity according to claim 9, characterized in that: When the thickness of the welded gas diffusion layer is tested, multiple points are taken on the gas diffusion layer, and detection probes are arranged above the points. Data from multiple points are collected to quickly provide feedback on the thickness of the gas diffusion layer.

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