A porous metal plate with an ultra-thin microporous layer and a preparation method thereof

Abstract

This application relates to a porous metal plate with an ultra-thin microporous layer. The ultra-thin microporous layer is one or more layers, the thickness of the ultra-thin microporous layer is 0.01 - 0.1 mm, the porosity is 10 - 60%, and the average pore diameter is 3 - 35 μm. The preparation method of the ultra-thin microporous layer includes preparing a bonding liquid, preparing the ultra-thin microporous layer, debinding, and sintering. The porous metal plate of this application has an ultra-thin microporous layer with a single-layer powder particle size, which increases the contact area while reducing the transmission resistance, reduces the surface roughness of the microporous layer, and greatly reduces the contact resistance.

Description

Technical Field

[0001] This application relates to a porous metal plate with an ultra-thin microporous layer and a preparation method thereof. Background Art

[0002] Porous metal plates and their preparation methods are mainly used in fields such as fuel cells, hydrogen production by electrolysis of water, electrocatalytic reduction, water treatment, medical devices, etc., such as the porous transport layer in the field of proton exchange membrane (PEM) water electrolysis for hydrogen production. Introducing a microporous layer on the surface of the porous transport layer can greatly improve the performance, durability, and stability of the proton exchange membrane electrolyzer. The main reasons are that the microporous layer has a smaller surface roughness, smaller pore size, and larger contact area than the single-layer transport layer, thus reducing the interfacial contact resistance with the catalytic layer, improving the utilization rate of the catalyst, protecting the membrane from being pierced by the fibers of the base layer of the transport layer, and promoting the transport of water / gas.

[0003] There are mainly three methods for preparing the microporous layer used in the porous transport layer in the prior art.

[0004] The first is vacuum plasma spraying, that is, titanium particles are melted and then accelerated onto the base layer. For example, DE102015111918A1 discloses a current collector, a membrane unit, and an electrochemical cell, and a microporous layer composed of titanium is applied to the substrate by vacuum plasma spraying. The advantage of this method is that the prepared microporous layer has few impurities and pollutants and can produce high-quality deposits, but the disadvantages are also obvious. The equipment is expensive and the cost is extremely high.

[0005] The second is composite hot pressing and sintering, that is, the microporous layer and the base layer are prepared separately first, and then laminated and hot pressed and sintered. For example, CN115642262A discloses a preparation method of a powder composite gas diffusion layer, in which the microporous layer is sintered into a sheet and then composite sintered with a powder-sintered titanium base layer. The cost of this method is relatively low, but the disadvantages are that it is difficult to make the single microporous layer thin, and secondly, although there are no obvious interfacial gaps macroscopically after the microporous layer and the base layer are hot pressed and sintered, interfacial gaps formed between the microporous layer and the base layer can be clearly seen at the electron microscope scale, which will cause the situation of water accumulation and gas cannot be discharged during the single cell operation.

[0006] The third is the method of scraping or spraying slurry, that is, the microporous layer is prepared into slurry, and then sprayed on the surface of the base layer through a casting and scraping or spraying device, and then sintered. The advantage of this method is that the preparation process is relatively simple, but it has high requirements for the accuracy of the equipment, the equipment is expensive, and the microporous layer is extremely prone to unevenness.

[0007] The above-mentioned microporous layer preparation methods all have certain problems, and the prepared transport layers with microporous layers also have various problems. Now there is an urgent need to obtain a transport layer with better transport performance and better interfacial contact performance, as well as a preparation method with lower process cost and higher production efficiency. Summary of the Invention

[0008] To achieve the above-mentioned invention object, the present application provides the following technical solutions:

[0009] The present application provides a porous metal plate with an ultra-thin microporous layer. The porous metal plate includes a substrate layer and an ultra-thin microporous layer on the substrate layer. The ultra-thin microporous layer is one or more layers, the thickness of the ultra-thin microporous layer is 0.01 - 0.1 mm, the porosity is 10 - 60%, and the average pore diameter is 3 - 25 μm.

[0010] The present application also provides a preparation method for a porous metal plate with an ultra-thin microporous layer, including the following steps:

[0011] Step of preparing the bonding liquid: Dissolve the binder in the solvent to form the bonding liquid;

[0012] Step of preparing the ultra-thin microporous layer: Spray the bonding liquid on the base film tape, then obtain small-particle-size metal powder using a sieve, cover a layer of the small-particle-size metal powder on the base film tape, remove the unbonded powder after standing and drying to obtain the green body of the porous metal plate;

[0013] Steps of debinding and sintering: Debind and sinter the green body of the porous metal plate to obtain a porous metal plate with an ultra-thin microporous layer.

[0014] Based on the above technical solutions, it can be seen that the porous metal plate and its preparation method of the present application have at least one of the following beneficial effects compared with the prior art:

[0015] (1) The porous metal plate of the present application has an ultra-thin microporous layer with a single-layer powder particle size, which increases the contact area while reducing the transmission resistance, reduces the surface roughness of the microporous layer, and greatly reduces the contact resistance.

[0016] (2) Compared with the vacuum plasma spraying and doctor blade coating processes, the preparation method of the present application includes preparing a casting slurry, casting, drying and demolding, preparing the bonding liquid, preparing the green body, debinding and sintering, which is cheap and simple, can avoid using expensive equipment, and has excellent interfacial bonding, greatly reducing the cost and being suitable for industrial production.

[0017] (3) Use the bonding liquid to adhere the microporous layer powder to the green body of the substrate layer. The bonding liquid has excellent viscosity and is easily decomposed and removed at low temperature without residue. Description of the Drawings

[0018] The following further describes the present application with reference to the drawings:

[0019] Figure 1 is the process flow chart of the preparation of the porous metal plate of the present application. Detailed Embodiments

[0020] To make the objectives, technical solutions and advantages of this application more clear and understandable, the following further elaborates on this application in conjunction with specific embodiments.

[0021] In one embodiment, the porous metal plate includes a substrate layer and an ultra-thin microporous layer on the substrate layer.

[0022] In one embodiment, the metal of the porous metal plate is titanium, nickel, a titanium alloy or a nickel alloy.

[0023] In one embodiment, the titanium alloy is Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-2Al-2.5Zr, Ti-8Mn, Ti-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr-2Mo, Ti-3Al-5Mo-4.5V, Ti-6Al-2Sn-4Zr-2Mo, Ti-5Mo-5V-8Cr-3A1, Ti-13V-11Cr-3Al, Ti-2.25Al-11Sn-5Zr-1Mo-0.2Si, Ti-6Al-2Zr-1Mo-1V, Ti-15V-3Cr-3Sn-3Al or Ti-8Al-1Mo-1V; and the nickel alloy is Inconel 600, Inconel 601, Inconel 625, Inconel 690, Inconel 718, Inconel 800, Inconel825, Inconel 901, Hastelloy B, Hastelloy C, Hastelloy X, Hastelloy R or Hastelloy G.

[0024] In one embodiment, compared with a porous metal plate of the same thickness without the ultra-thin microporous layer, the porous metal plate with the ultra-thin microporous layer has a contact resistance reduction of more than 25% at 2 MPa, and the ultra-thin microporous layer has a single-layer powder particle size.

[0025] The preparation process flow of the porous metal plate of this application is as Figure 1 shown.

[0026] This process mainly consists of five major steps. The first step is to prepare the casting slurry by mixing the powders and organic substances required for the base layer to form a slurry. The second step is casting, drying, and demolding. The mixed slurry is cast into a shape and heated and dried to obtain a base layer film strip. The third step is to prepare the bonding liquid, which is an organic substance with a certain viscosity and is easy to sinter and remove. The fourth step is to prepare the green body of the porous metal plate. The powder of the required size for the microporous layer is screened onto the film strip sprayed with the bonding liquid through a sieve, and the unbonded powder is shaken off after drying, thus obtaining a green body with an ultra-thin microporous layer. The fifth step is to degrease and sinter the said green body.

[0027] In one embodiment, in the step of preparing the casting slurry, the particle size of the metal powder is 30 - 150 μm, and it can also be 40 - 120 μm, 50 - 100 μm, 60 - 90 μm, 70 - 80 μm.

[0028] In one embodiment, in the step of casting, drying, and demolding, the base layer film strip includes PET, PP, and / or PE. The drying method is vacuum or argon drying, the drying time is 1 h - 5 h, the drying temperature is 30 - 80 °C, and the thickness of the base layer green body is 0.05 - 1 mm.

[0029] In one embodiment, in the step of preparing the bonding liquid, the binder includes polyacrylic acid resin and paraffin, the solvent includes ethyl acetate and isopropyl alcohol. The mass ratio of the binder in the bonding liquid is 10 - 20 wt%, and the viscosity of the bonding liquid is 5 - 100 pa·s.

[0030] In one embodiment, in the step of preparing the green body, the sieve is 180 - 1200 mesh, and it can also be 250 - 1000 mesh, 300 - 700 mesh, 350 - 500 mesh, 400 - 450 mesh. The static drying time is 0.5 - 1 h.

[0031] In one embodiment, in the steps of degreasing and sintering, the degreasing method is degreasing in an inert atmosphere, the degreasing temperature is 300 - 500 °C, the heating rate is 0.5 - 5 °C / min, and the holding time is 0.5 - 3 h. The sintering method is sintering in an inert atmosphere or a vacuum environment, the sintering temperature is 800 - 1300 °C, the heating rate is 2 - 5 °C / min, and the holding time is 0.5 - 3 h.

[0032] Hereinafter, in combination with specific embodiments, the preparation method of the porous metal plate of the present application will be further elaborated. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve it. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all regarded as included in the present application. The method and application of the present application have been described through preferred embodiments, and those related can obviously make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of the present application to implement and apply the technology of the present application.

[0033] Example 1

[0034] A method for preparing a porous metal plate with an ultra-thin microporous layer, the method comprising the following steps:

[0035] (1) In a glove box, dissolve PVB and PEG in ethanol, add large-particle-size titanium powder with an average particle size of 50 μm, and perform mechanical stirring, and then perform degassing treatment. The mass ratio of PVB, PEG, alcohol to the powder is 1 wt%: 0.25 wt%: 38.75 wt%: 60 wt%.

[0036] (2) Cast and form the slurry obtained in step (1) at 25°C, and dry and demold at 45°C to obtain a base layer film strip.

[0037] (3) Dissolve polycarbonate propylene in ethyl acetate to form a bonding liquid, spray the bonding liquid on the base layer film strip, and then use a 700-mesh sieve to cover a layer of small-particle-size titanium powder on the surface of the film strip. After standing and drying, blow off the unbonded powder to obtain a green body.

[0038] (4) Debind and sinter the green body. Debinding is carried out in an inert atmosphere, the debinding temperature is 450°C, the heating rate is 2°C / min, the holding time is 3 h, the sintering temperature is 900°C, the heating rate is 3°C / min, the holding time is 2 h, and finally it is naturally cooled to room temperature, and then the porous titanium-based metal plate with the ultra-thin microporous layer is obtained.

[0039] The overall thickness of the porous titanium-based metal plate with the ultra-thin microporous layer is 0.25 mm, and the contact resistance is 0.31 mΩ·cm 2 @2 MPa, the contact resistance is reduced by 27% compared with a metal plate of the same thickness without an ultra-thin microporous layer, the tensile strength is 22 Mpa, the thickness of the base layer is 0.21 mm, the porosity is 45%, the average pore diameter is 18 μm, the thickness of the ultra-thin microporous layer is 0.04 mm, the porosity is 30%, the average pore diameter is 6 μm, the surface roughness Ra of the microporous layer is 4.2 μm. Compared with a 0.25-mm sample without a microporous layer, its overpotential is reduced by 15 mv at 2 A / cm 2 and the performance is greatly improved.

[0040] Example 2

[0041] A method for preparing a porous metal plate with an ultrathin microporous layer, the method comprising the following steps:

[0042] (1) In a glove box, dissolve PVB and PEG in ethanol, add titanium powder with a large particle size of 50 μm on average, and perform mechanical stirring, and then perform defoaming treatment. The mass ratio of PVB, PEG, alcohol to powder is 1 wt%: 0.25 wt%: 38.75 wt%: 60 wt%.

[0043] (2) Cast and form the slurry obtained in step (1) at 25 °C, and dry and demold at 45 °C to obtain a base layer film strip.

[0044] (3) Dissolve polycarbonate propylene in ethyl acetate to form a bonding liquid, spray the bonding liquid on the base layer film strip, then use a 1000-mesh sieve to cover a layer of titanium powder with a small particle size on the surface of the film strip, and blow off the unbonded powder after standing and drying to obtain a green body.

[0045] (4) Debind and sinter the green body, perform debinding in an inert atmosphere, the debinding temperature is 450 °C, the heating rate is 2 °C / min, the holding time is 3 h, the sintering temperature is 900 °C, the heating rate is 3 °C / min, the holding time is 2 h, and finally cool naturally to room temperature, and then obtain the porous titanium-based metal plate with the ultrathin microporous layer.

[0046] The overall thickness of the porous titanium-based metal plate with the ultrathin microporous layer is 0.2 mm, and the contact resistance is 0.28 mΩ·cm 2 @2 MPa, the contact resistance is reduced by 30% compared with a metal plate of the same thickness without an ultrathin microporous layer, the tensile strength is 15 Mpa, the thickness of the base layer is 0.18 mm, the porosity is 38%, the average pore size is 16 μm, the thickness of the ultrathin microporous layer is 0.02 mm, the porosity is 25%, the average pore size is 4 μm, the surface roughness Ra of the microporous layer is 3 μm, compared with a sample without a microporous layer of 0.2 mm, its overpotential is reduced by 25 mv at 2 A / cm 2 and the performance is greatly improved.

[0047] The above is only the preferred embodiment of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present application.

Claims

1. A porous metal plate with an ultra-thin microporous layer, the porous metal plate comprising a substrate layer and an ultra-thin microporous layer on the substrate layer, the ultra-thin microporous layer being one or more layers, characterized in that: The ultra-thin microporous layer has a thickness of 0.01-0.04 mm, a porosity of 10-60%, an average pore size of 3-35 μm, and the metal is titanium or a titanium alloy; The preparation method of the porous metal plate comprises: Preparation of casting slurry, casting and drying, preparation of bonding liquid, preparation of ultra-thin microporous layer, debinding and sintering; In the step of preparing the casting slurry, the powder required for the base layer and the organic matter are mixed into a slurry; In the casting and drying steps, the mixed slurry is cast and formed, and then dried to obtain a base layer film tape; In the step of preparing the adhesive liquid, a binder is dissolved in a solvent to form the adhesive liquid, wherein the binder comprises polyacrylic resin and paraffin, the solvent comprises ethyl acetate and isopropanol, the mass ratio of the binder to the adhesive liquid is 10-20wt%, and the viscosity of the adhesive liquid is 5-100pa•s; In the step of preparing the ultra-thin microporous layer, the bonding liquid is sprayed on the substrate layer membrane tape, and then a screen is used to obtain small-particle metal powder. A layer of the small-particle metal powder is covered on the substrate layer membrane tape, and the unbonded powder is removed after standing and drying to obtain the green body of the porous metal plate. The screen is 180-1200 mesh, and the standing and drying time is 0.5-1h.

2. The porous metal plate according to claim 1, characterized in that The titanium alloys are Ti-6Al-4V, Ti-5Al-2.5Sn, Ti-6Al-7Nb, Ti-3Al-2.5V, Ti-2Al-2.5Zr, Ti-8Mn, T i-6Al-6V-2Sn, Ti-6Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn-4Zr-2Mo, Ti-6Al-2Sn-2Zr-2Mo, Ti- 3Al-5Mo-4.5V, Ti-6Al-2Sn-4Zr-2Mo, Ti-5Mo-5V-8Cr-3A1, Ti-13V-11Cr-3Al, Ti-2.25 Al-11Sn-5Zr-1Mo-0.2Si, Ti-6Al-2Zr-1Mo-1V, Ti-15V-3Cr-3Sn-3Al or Ti-8Al-1Mo-1V.

3. A method for preparing a porous metal plate according to any one of claims 1 to 2, characterized in that: The following steps are involved: Preparing casting slurry: mixing the powder required for the base layer and organic matter into slurry; Casting and drying: Cast the mixed slurry into a tape and dry it to obtain a base layer film tape; Preparing a bonding liquid: dissolving a bonding agent in a solvent to form a bonding liquid; Preparation of ultra-thin microporous layer: spraying the bonding liquid on the substrate film strip, then using a screen to obtain small-particle metal powder, covering the substrate film strip with a layer of the small-particle metal powder, standing and drying, and removing unbonded powder to obtain the green body of the porous metal plate; Debinding and sintering: debinding and sintering the green body of the porous metal plate to obtain a porous metal plate with an ultra-thin microporous layer; In the step of preparing the adhesive solution, the adhesive comprises polyacrylic resin and paraffin, the solvent comprises ethyl acetate and isopropanol, the mass ratio of the adhesive to the adhesive solution is 10-20wt%, and the viscosity of the adhesive solution is 5-100pa•s; In the step of preparing the ultra-thin microporous layer, the mesh size is 180-1200 meshes, and the static drying time is 0.5-1 hour.

4. The method for preparing a porous metal plate according to claim 3, characterized in that: In the debinding and sintering steps, the debinding method is to carry out the debinding in an inert atmosphere, the debinding temperature is 200-600°C, the heating rate is 0.5-5°C / min, and the insulation time is 0.5-12h. The sintering method is to carry out the sintering in an inert atmosphere or a vacuum environment, the sintering temperature is 800-1300°C, the heating rate is 0.5-10°C / min, and the insulation time is 0.5-12h.

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