阅读说明：本技术 一种燃料电池金属连接体涂层 (Fuel cell metal connector coating ) 是由 郑莉莉 李希超 韦守李 戴作强 张洪信 于 2021-06-22 设计创作，主要内容包括：本发明属于燃料电池材料技术领域。针对固体氧化物燃料电池的合金连接体Cr的挥发问题以及质子交换膜燃料电池的金属双极板的易腐蚀问题,本发明提供一种金属连接体涂层,所述涂层为Ti-(3)SiC-(2)陶瓷或者掺杂改性固溶体材料(Ti,M)-(3)SiC-(2),其中M选自Nb、Ta、W和V材料中的一种。该涂层为Ti-(3)SiC-(2)陶瓷或者其掺杂改性固溶体材料,具有均匀、致密、附着力高,能够长期有效地抑制金属连接体中所含的Cr元素向外迁移,解决阴极中毒的问题,能降低Cr-(2)O-(3)膜的生长速率,降低连接体的工作电阻,提高不锈钢连接体的综合工作性能；还可以用于质子交换膜燃料电池的金属双极板,有效提高质子交换膜燃料电池双极板的耐腐蚀能力和导电性能。(The invention belongs to the technical field of fuel cell materials. Aiming at the problem of volatilization of Cr of an alloy connector of a solid oxide fuel cell and the problem of easy corrosion of a metal bipolar plate of a proton exchange membrane fuel cell, the invention provides a metal connector coating which is Ti 3 SiC 2 Ceramic or doped modified solid solution material (Ti, M) 3 SiC 2 Wherein M is selected from one of Nb, Ta, W and V materials. The coating is Ti 3 SiC 2 Ceramics or the likeThe doped modified solid solution material has the advantages of uniformity, compactness and high adhesive force, can effectively inhibit the outward migration of Cr element contained in a metal connector for a long time, solves the problem of cathode poisoning, and can reduce Cr 2 O 3 The growth rate of the membrane reduces the working resistance of the connector and improves the comprehensive working performance of the stainless steel connector; the metal bipolar plate can also be used for a metal bipolar plate of a proton exchange membrane fuel cell, and the corrosion resistance and the conductivity of the bipolar plate of the proton exchange membrane fuel cell are effectively improved.)

1. A metal interconnect coating for a fuel cell, wherein said coating is Ti₃SiC₂Or doping modified solid solution material (Ti, M)₃SiC₂Wherein M is selected from one of Nb, Ta, W and V materials.

2. The metal interconnect coating of claim 1, wherein the metal interconnect coating is deposited on the surface of the metal interconnect by a method comprising: pretreating the metal connector; with Ti₃SiC₂Or doping modified solid solutions (Ti, M)₃SiC₂The target material is a target material block, M is any one of Nb, Ta, V or W, and the target material is deposited on the surface of the metal connector by adopting a magnetron sputtering method or an arc ion plating method.

3. The metal interconnect coating of claim 2, wherein the metal interconnect is a ferritic stainless steel: any one of SUS430, Crofer22APU, Fe-10Cr, 1.4724, Fe-17Cr-0.2Y, 1.4016, Ferrotherm (1.4742), Fe-18Cr-9W, Fe-20Cr-7W, Fe-20Cr, AL 453, 1.4763(446), FeCrMn (LaTi), Fe-Cr-Mn, Fe-25Cr-DIN 50049, Fe-25Cr-0.1Y-2.5Ti, Fe-25Cr-0.2Y-1.6Mn, Fe-25Cr-0.4La, Fe-25Cr-0.3Zr, Fe26CrTiY, Fe26CrTiNbY, Fe26CrMoTiY, E-Brite, Al29-4C or Fe-30 Cr.

4. The metal interconnect coating of claim 2, wherein the Ti₃SiC₂Ceramic or doped modified solid solution bulk material (Ti, M)₃SiC₂The preparation method comprises the following steps: originalThe powder material comprises Ti powder, silicon powder and graphite powder, the solid solution also comprises any one of Nb powder, Ta powder, W powder and V powder, and the powder material is prepared by sintering in a hot pressing furnace by adopting a hot pressing/solid-liquid phase reaction method, wherein the sintering temperature is 1000-1700 ℃, the heat preservation time is 15-60 minutes, the hot pressing pressure is 10-60 MPa, and flowing argon gas is used as protective gas.

5. The metal interconnect coating of claim 2, wherein the coating is deposited on the surface of the alloy by an arc ion plating apparatus or a magnetron sputtering apparatus, wherein the sample is suspended on a sample holder of the apparatus during the deposition of the coating, and the rotating column for suspending the sample is rotatable while the rotating column is rotatable around a rotating table, thereby obtaining a uniform coating.

6. The metal interconnect coating of claim 2, wherein the metal interconnect is pretreated by: firstly, sand paper is selected to polish and polish the metal connector, namely, metallographic sand paper of 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# is used for polishing step by step, then the polished metal connector sample is subjected to ultrasonic cleaning for 5-30 min by acetone, alcohol and deionized water respectively, and then is dried in the air for later use.

7. The metal interconnect coating of claim 2, wherein said arc ion plating process, prior to coating preparation, pre-vacuums the vacuum chamber to a background vacuum of 5 x 10^-3After Pa, applying 500V negative pulse bias voltage on the substrate to carry out back-splash cleaning on the substrate for 5-15 min, and removing pollutants and an oxidation layer on the surface of the substrate; then opening an Ar flow valve, wherein the flow rate of Ar gas is 50ml/min, and controlling the working air pressure in the vacuum chamber by adjusting the pumping speed of the molecular pump to keep the working air pressure at about 0.4Pa, wherein the heating temperature of the chamber is 200-700 ℃; then turning on a direct current power supply, wherein the arc current is 30-70A, the bias voltage is-400 to-500V, and the sputtering time is 10-60 min; after deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped.

8. According to the rightThe metal interconnect coating of claim 2, wherein the magnetron sputtering process is preceded by a pre-evacuation to 5 x 10 prior to coating preparation^-4Pa, to minimize the contamination of residual gases during sputtering; introducing high-purity Ar gas with the flow rate of 30ml/min after the vacuum degree required by the experiment is reached, and adjusting the working air pressure to be kept at 0.25-0.35 Pa; first using Ar before the start of deposition⁺Cleaning the target material to remove pollutants on the surface of the target material, wherein the cleaning time is 5-15 min, then heating the sample to 100-800 ℃, and keeping the temperature for 15min, so that the whole sample starts to be sputtered to prepare the coating after the temperature is uniform, and in the preparation process of the coating, the sputtering power is 0.1-2.5 kw, and the sputtering time is 1-6 h; after deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped.

9. A metal interconnect for a fuel cell, characterized in that it has a coating according to claim 1.

Technical Field

The invention belongs to the technical field of fuel cell materials, and particularly relates to a metal connector coating of a fuel cell.

Background

The Solid Oxide Fuel Cell (SOFC) has the advantages of capability of using carbon-containing Fuel, high power generation efficiency, low power generation cost and the like, and has wide application prospects in the fields of distributed power stations, power sources and the like. Although there are some stacks that have been demonstrated to operate worldwide, their large-scale commercial application is still limited by the materials of the various components. Wherein the connector material is one of the development bottlenecks of the SOFC. The connector (also called connecting plate or bipolar plate) is a key component for assembling the flat SOFC stack, and on one hand, the connector is electrically connected with adjacent monocells; on the other hand, the fuel gas of the anode is separated from the air of the cathode, and the performance of the fuel gas directly influences the output power and the service life of the SOFC electric stack.

After 90 years, with the development of electrolyte materials, the service temperature of solid oxide fuel cells is reduced to 600-800 ℃, so that the alloy can be used as a connector material, wherein the alloy mainly comprises chromium-based alloy, nickel-based alloy and iron-based alloy, and at present, the iron-based alloy represented by SUS430 and Crofer22APU is a main choice of the connector material due to the advantages of low price, good oxidation resistance and electrical conductivity, good matching property of thermal expansion coefficient with other components and the like. Alloy interconnect materials have their own advantages but also have fatal disadvantages, the most fatal of which is the problem of volatilization of chromium compounds. In order to make the connector material have certain oxidation resistance and conductivity under the working environment, the alloy connector material contains certain chromium to generate a chromium oxide film. The chromium oxide forms volatile chromium compounds in the working environment, and the compounds poison the cathode, so that the output performance of the battery is reduced, and finally the aging of the galvanic pile is accelerated.

Aiming at the problem of volatilization of Cr in the alloy connector, protective coating is applied on the surface of the alloy connectorLayers are an important means. The protective coating applied to the surface of the alloy connector at present mainly comprises: reactive oxide coatings (such as Y, La, Ce and oxides thereof), conductive perovskite coatings and conductive spinel structure coatings. The reaction oxide coating is formed by depositing a thin layer of reaction substances such as Y, La, Ce and the like on the alloy connector, so that the thickness of the film is effectively reduced, and the binding force of the oxide film is increased. However, the use of a large amount of rare earth elements makes the coating expensive, which is not favorable for reducing the cost of the interconnect. The perovskite coating is limited by a preparation method, the film layer is difficult to reach 100% compactness, and oxygen can be diffused through the film layer to continuously increase the thickness of the oxide layer of the substrate; further, the film layer contains a small amount of ion conductivity, and the diffusion of Cr cannot be suppressed completely and effectively. Neither reactive oxide coatings nor perovskite coatings have been commercially applied. Conductive spinel structure coating with molecular formula AB₂O₄The A and B sites are transition elements, so that the Cr element diffusion resistance is good, and the method is a current research hotspot. However, mutual diffusion between the alloy substrate and the coating system is easy to occur, and the structural stability needs to be improved, so that the components of the oxide layer can be correspondingly changed along with the extension of the working time, the resistance of the connecting plate is increased, and the binding force of the protective film is influenced.

Proton Exchange Membrane Fuel Cells (PEMFCs) have the advantages of low operating temperature, zero emission, high specific power, high energy conversion rate and the like, and have wide prospects in the fields of automotive power supplies, portable equipment, aviation and the like. PEMFCs are mainly composed of a membrane electrode assembly, a bipolar plate, an end plate, a sealing member, and the like. The bipolar plate is a core multifunctional component of the PEMFCs, plays roles in uniformly distributing gas, draining water, conducting heat, conducting electricity and the like, accounts for 60% of the whole fuel cell by mass, accounts for 15% -20% of the cost, and directly influences the service life and the commercialization process of the cell by the performance and the cost. The traditional graphite bipolar plate is gradually replaced by a metal bipolar plate with strong machinability, excellent electric and thermal conductivity and good mechanical property due to large volume, high manufacturing cost and poor mechanical property. However, in the acidic working environment of the battery, the metal polar plate is easy to corrode, the ion transmission efficiency of the proton exchange membrane is reduced due to metal ions formed in the corrosion process, and meanwhile, the interface contact resistance is increased due to a passive film formed on the surface of the metal bipolar plate, so that the performance of the fuel battery is reduced. Based on the characteristics, the novel coating designed and researched by the invention has the characteristics of compactness, high adhesive force and uniformity, and is a good anti-oxidation corrosion coating for the metal material.

Disclosure of Invention

Aiming at the problem of volatilization of Cr of an alloy connector of a solid oxide fuel cell and the problem of easy corrosion of a metal bipolar plate of a proton exchange membrane fuel cell, the invention provides a metal connector coating which is Ti₃SiC₂Ceramics or their doped modified solid solution materials (Ti, M)₃SiC₂(M is one of Nb, Ta, W and V), has the advantages of uniformity, compactness and high adhesive force, can effectively inhibit the outward migration of Cr element contained in the metal connector for a long time, solves the problem of cathode poisoning, and can reduce Cr₂O₃The growth rate of the membrane reduces the working resistance of the connector and improves the comprehensive working performance of the stainless steel connector; meanwhile, the metal bipolar plate can be used for a metal bipolar plate of a proton exchange membrane fuel cell, and the corrosion resistance and the conductivity of the bipolar plate of the proton exchange membrane fuel cell are effectively improved.

The invention is realized by the following technical scheme:

a metal interconnect coating for a fuel cell, said coating being Ti₃SiC₂Ceramics or their doped modified solid solution materials (Ti, M)₃SiC₂Wherein M is selected from any one of Nb, Ta, W and V materials. The surface of the coating can be oxidized in the use temperature range of the solid oxide fuel cell or in the use environment of the proton exchange membrane fuel cell to form an oxide film with compact microstructure and long-acting effect.

Further, the deposition method of the metal connector coating on the surface of the metal connector comprises the following steps: pretreating the metal connector, and then using Ti₃SiC₂Ceramics or doped modified solid solutions (Ti, M)₃SiC₂Depositing the target material on the surface of the metal connecting body by adopting a magnetron sputtering method or an electric arc ion plating method as the target materialAnd (5) kneading.

Further, the metal connector is a ferritic stainless steel: any one of SUS430, Crofer22APU, Fe-10Cr, 1.4724, Fe-17Cr-0.2Y, 1.4016, Ferrotherm (1.4742), Fe-18Cr-9W, Fe-20Cr-7W, Fe-20Cr, AL 453, 1.4763(446), FeCrMn (LaTi), Fe-Cr-Mn, Fe-25Cr-DIN 50049, Fe-25Cr-0.1Y-2.5Ti, Fe-25Cr-0.2Y-1.6Mn, Fe-25Cr-0.4La, Fe-25Cr-0.3Zr, Fe26CrTiY, Fe26CrTiNbY, Fe26Cr, MoTiY, E-Brite, Al29-4C or Fe-30 Cr.

Further, said Ti₃SiC₂Ceramics or doped modified solid solutions (Ti, M)₃SiC₂The preparation method comprises the following steps: selecting original powder materials comprising Ti powder, silicon powder and graphite powder, wherein the solid solution also comprises any one of Nb powder, Ta powder, W powder and V powder, wet-mixing the powder on a ball mill for 24 hours by a wet-mixing method, taking out the powder, naturally drying the powder in the air, and sieving the powder for later use; and sintering the sample in a hot pressing furnace by adopting a hot pressing/solid-liquid phase reaction method, wherein the sintering temperature is 1000-1700 ℃, the temperature is kept for 15-60 minutes, the hot pressing pressure is 10-60 MPa, and flowing argon is used as protective gas.

Further, an arc ion plating device or a magnetron sputtering device is utilized to deposit a coating on the surface of the alloy, the sample is hung on a sample rack of the equipment during the deposition of the coating, the stand column for hanging the sample can rotate, the rotating stand column can revolve along with the rotating table, and the rotation of the sample is to obtain uniform coating.

Furthermore, when a metal connector sample is prepared, the sample is pretreated, firstly, sand paper is selected to polish the metal connector, namely, 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# metallographic sand paper is used for polishing step by step, then the polished metal connector sample is subjected to ultrasonic cleaning for 5-30 min respectively through acetone, alcohol and deionized water, and then the sample is dried in the air for later use.

Further, the arc ion plating method is characterized in that before the coating is prepared, the vacuum chamber is pre-vacuumized until the back bottom vacuum is 5 multiplied by 10^-3After Pa, applying 500V negative pulse bias voltage on the substrate to carry out back-splash cleaning on the substrate for 5-15 min, and removing pollutants and an oxidation layer on the surface of the substrate; then opening the Ar flow valve, wherein the Ar gas flow is 50ml/min, controlling the working air pressure in the vacuum chamber by adjusting the pumping speed of the molecular pump to keep the working air pressure at about 0.4Pa, and controlling the heating temperature of the chamber to be 200-700 ℃; then turning on a direct current power supply, wherein the arc current is 30-70A, the bias voltage is-400 to-500V, and the sputtering time is 10-60 min; after deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped.

The magnetron sputtering method is characterized in that before the coating is prepared, the coating is firstly pre-vacuumized to 5 multiplied by 10^-4Pa, to minimize the contamination of residual gases during sputtering; introducing high-purity Ar gas with the flow rate of 30ml/min after reaching the vacuum degree required by the experiment, adjusting the working air pressure to be kept at 0.25-0.35 Pa, and firstly utilizing Ar gas before the deposition begins⁺Cleaning the target material to remove pollutants on the surface of the target material, wherein the cleaning time is 5-15 min, then heating the sample to 100-800 ℃, and keeping the temperature for 15min, so that the whole sample starts to be sputtered to prepare the coating after the temperature is uniform, and in the preparation process of the coating, the sputtering power is 0.1-2.5 kw, and the sputtering time is 1-6 h; after deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped.

A metal interconnect for a fuel cell, the metal interconnect having the coating described above.

The invention relates to a fuel cell metal connector with a novel coating and a preparation method thereof, wherein the novel coating is Ti₃SiC₂Ceramics and doped modified solid solution material ((Ti, M)₃SiC₂M is one of Nb, Ta, W and V); the preparation method of the metal connector comprises the following steps: pretreating the metal connector; then adopting magnetron sputtering method or arc ion plating method to deposit Ti on the surface of the metal connector₃SiC₂Ceramics or doped modified solid solutions thereof ((Ti, M)₃SiC₂M ═ Nb, Ta, W, V) coating, resulting in a metal interconnect with a novel coating attached to the surface. The invention has the beneficial effects that: can obtain a novel uniform, compact and high-adhesion coating which can effectively inhibit the outward migration of Cr element contained in a metal connector and reduce Cr₂O₃Film growth rate, decrease of film growth rateThe working resistance of the connector improves the comprehensive working performance of the stainless steel connector. Meanwhile, the novel coating designed and researched by the invention is a good oxidation and corrosion resistant coating for the metal material on the metal connector. In addition, the method has the advantages of simple process, low cost and easy realization of industrial production.

Compared with the prior art, the invention has the following advantages:

1. compared with a reaction oxide coating, the novel coating can easily obtain a coating with expected thickness, the bonding strength of the coating and a substrate is high, the raw materials (Ti, Si and C powder) used by the coating are low in price, and Nb, Ta, W and V powder is expensive but used for doping, is less in use and is easy to industrially popularize.

2. Compared with the perovskite coating, the coating can be dense, outward migration of Cr is effectively blocked, and the coating plays a great and substantial role in protecting the cathode.

3. Compared with the conductive spinel structure coating, the coating has stronger compatibility with an alloy matrix and can keep the stability of the structure for a long time.

4. And direct use of Ti₃SiC₂Compared with the connector, the connector is easier to process and has better applicability. Ti₃SiC₂The finished product rate of the connecting body is low, the processing and manufacturing cost is high, certain difficulty exists in synthesizing block materials or components with large size or complex shape, and Ti is limited₃SiC₂And large-scale application of solid solution materials thereof.

The fuel cell metal connector provided by the invention has uniform and compact coating and high adhesive force, can effectively inhibit the outward migration of Cr element contained in the metal connector for a long time, solves the problem of cathode poisoning, and can reduce Cr₂O₃The growth rate of the membrane reduces the working resistance of the connector and improves the comprehensive working performance of the stainless steel connector. Meanwhile, the coating material can also be used for a metal bipolar plate of a proton exchange membrane fuel cell, and the corrosion resistance of metal is improved. The raw materials (Ti, Si and C powder) used by the coating are low in price, and Nb, Ta, W and V powder is expensive, but is used for doping, is less in use and is easy to obtainAnd (5) industrial popularization.

Drawings

FIG. 1 is a schematic view showing the structure of an arc ion plating apparatus according to example 1; wherein, 1, a rotating platform; 2. a sample holder; 3. a partition plate; 4. a target material.

FIG. 2 shows (Ti, Nb) prepared by arc ion plating in example 1₃SiC₂The surface topography of the coating;

FIG. 3 shows (Ti, Nb) prepared by arc ion plating in example 1₃SiC₂The cross-sectional morphology of the coating;

FIG. 4 shows example 1 deposition (Ti, Nb)₃SiC₂A surface microstructure of the coated SUS430 stainless steel interconnector after oxidation at 800 ℃;

FIG. 5 shows example 1 deposition (Ti, Nb)₃SiC₂A cross-sectional microstructure of the coated SUS430 stainless steel interconnector after oxidation at 800 ℃;

FIG. 6 shows (Ti, W) prepared by the magnetron sputtering method of example 2₃SiC₂The surface topography of the coating;

FIG. 7 shows Ti prepared by arc ion plating in example 3₃SiC₂Surface topography of the coating.

Detailed Description

The present invention will be described in further detail with reference to the following embodiments and the accompanying drawings.

The metallic interconnect material used in the following examples is a ferritic stainless steel alloy, commercially available from one of SUS430, Crofer22APU, Fe-10Cr, 1.4724, Fe-17Cr-0.2Y, 1.4016, Ferrotherm (1.4742), Fe-18Cr-9W, Fe-20Cr-7W, Fe-20Cr, AL 453, 1.4763(446), FeCrMn (LaTi), Fe-Cr-Mn, Fe-25Cr-DIN 50049, Fe-25Cr-0.1Y-2.5Ti, Fe-25Cr-0.2Y-1.6Mn, Fe-25Cr-0.4La, Fe-25Cr-0.3Zr, Fe26CrTiY, Fe26CrTiNbY, Fe26CrMoTiY, E-Bri 29-4C, or Fe-30 Cr.

Ti for deposition₃SiC₂Ceramics and doped modified solid solution material ((Ti, M)₃SiC₂M is one of Nb, Ta, W and V) target material. The preparation method comprises the following steps: the original powder comprises Ti powder, silicon powder and graphite powder, and the solid solution also comprises Nb powder and Ta powderAnd any one of the W powder and the V powder is prepared by sintering in a hot pressing furnace by a hot pressing/solid-liquid phase reaction method, wherein the sintering temperature is 1000-1700 ℃, the temperature is kept for 15-60 minutes, the hot pressing pressure is 10-60 MPa, and flowing argon is used as protective gas.

Example 1

Will (Ti, Nb)₃SiC₂The coating was deposited on the surface of the SUS430 stainless steel interconnect. First of all (Ti, Nb)₃SiC₂Bulk target material, and commercially available SUS430 stainless steel alloy. And (2) gradually polishing the alloy matrix by using 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# metallographic abrasive paper, then respectively ultrasonically cleaning the polished metal connector sample for 15min by using acetone, alcohol and deionized water, and drying the metal connector sample in the air for later use.

And depositing a coating on the surface of the alloy by using an arc ion plating device. The arc ion plating device comprises a rotary table, a partition plate is arranged on the upper surface of the rotary table, the space above the rotary table is divided into a plurality of relatively independent spaces, a sample frame is arranged in the independent spaces, an upright post of the sample frame can rotate, and the upright post can revolve along with the rotary table.

The sample is first suspended on a sample holder of the apparatus (as shown in fig. 1), and the column of the sample holder can rotate while the rotating column can revolve with the rotating table. Before the coating is prepared, the vacuum chamber is pre-vacuumized until the back bottom vacuum is 5 multiplied by 10^-3And after Pa, applying 500V negative pulse bias voltage on the substrate to carry out back-splash cleaning on the substrate for 10min, and removing pollutants and an oxidation layer on the surface of the substrate. Then opening an Ar flow valve, wherein the flow rate of Ar gas is 50ml/min, controlling the working air pressure in the vacuum chamber to be maintained at about 0.4Pa by adjusting the pumping speed of the molecular pump, and the heating temperature of the chamber is 500 ℃. Then, a direct current power supply is switched on, the arc current is 40A, the bias voltage is-500V, and the sputtering time is 20 min. After deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped. Finally, the microscopic appearance of the surface and the section of the deposited coating is observed by a scanning electron microscope, so that (Ti, Nb)₃SiC₂The coating is dense, flat, free of pores, and bonds well to the substrate, with a thickness of about 3 μm (as shown in fig. 2 and 3).

The deposit (Ti, Nb)₃SiC₂After the SUS430 stainless steel connector of the coating is oxidized at 600-800 ℃, a compact and continuous oxide film structure (shown in figures 4 and 5) is formed on the surface of the SUS430 stainless steel connector, and the volatilization of Cr can be effectively blocked, so that the problem of cathode poisoning of an SOFC (solid oxide Fuel cell) is solved, and meanwhile, Cr can be reduced₂O₃The growth rate of the film. Meanwhile, after oxidation, the surface specific resistance of the oxide film is reduced by 30 percent, which shows that the preparation of the coating reduces the working resistance of the connector, effectively improves the conductivity of the alloy connector material and improves the comprehensive working performance of the stainless steel connector.

Example 2

Will (Ti, W)₃SiC₂The coating was deposited on the surface of Crofer22APU stainless steel interconnect. First of all (Ti, W)₃SiC₂Bulk target material and commercially available Crofer22APU stainless steel alloy. And (2) gradually polishing the alloy matrix by using 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# metallographic abrasive paper, then respectively ultrasonically cleaning the polished metal connector sample for 10min by using acetone, alcohol and deionized water, and drying the metal connector sample in the air for later use.

The magnetron sputtering equipment is used for depositing a coating on the surface of the alloy, firstly, a sample is hung on a sample rack of the equipment (shown in figure 1), and a stand column of the sample can rotate, and meanwhile, the rotating stand column can revolve with a rotating table. Before the coating is prepared, firstly, the vacuum is pre-pumped to 5X 10^-4Pa to minimize contamination of residual gases during sputtering. After reaching the vacuum degree required by the experiment, high-purity Ar gas with the flow rate of 30ml/min is introduced, and the working air pressure is adjusted to be kept at 0.30 Pa. First using Ar before the start of deposition⁺And cleaning the target material to remove pollutants on the surface of the target material, wherein the cleaning time is 10 min. Then the sample is heated to 700 ℃ and kept warm for 15min, so that the temperature of the whole sample is uniform, and then sputtering is started to prepare the coating. In the preparation process of the coating, the sputtering power is 0.2kw, and the sputtering time is 5 h. After deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped. Finally, the microscopic appearance of the surface and the section of the deposited coating is observed by a scanning electron microscope, and after the deposition, (Ti, W)₃SiC₂The coating is dense, flat, free of pores (as shown in fig. 6), and well bonded to the substrate, with a thickness of about 4.5 μm under these conditions.

The deposit (Ti, W)₃SiC₂After the coated Crofer22APU stainless steel connector is oxidized for 100 hours at 800 ℃, a compact oxide film is formed on the surface, the volatilization of Cr can be effectively blocked, meanwhile, after the oxidation, the surface specific resistance of the oxide film is found to be reduced by 10% compared with that of the alloy without the coating, the working resistance of the connector is reduced by the preparation of the coating, and the comprehensive working performance of the alloy connector is effectively improved.

Example 3

Mixing Ti₃SiC₂The coating was deposited on the surface of the Fe-17Cr-0.2Y stainless steel interconnect. First, Ti is prepared₃SiC₂Bulk target material and commercial Fe-17Cr-0.2Y stainless steel alloy. And (2) gradually polishing the alloy matrix by using 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# metallographic abrasive paper, then respectively ultrasonically cleaning the polished metal connector sample for 20min by using acetone, alcohol and deionized water, and drying the metal connector sample in the air for later use.

The arc ion plating equipment is used for depositing a coating on the surface of the alloy, firstly, a sample is hung on a sample rack of the equipment (shown in figure 1), and a stand column of the sample can rotate, and meanwhile, the rotating stand column can revolve along with the rotating table. Before the coating is prepared, the vacuum chamber is pre-vacuumized until the back bottom vacuum is 5 multiplied by 10^-3And after Pa, applying 500V negative pulse bias voltage on the substrate to carry out back-splash cleaning on the substrate for 15min, and removing pollutants and an oxidation layer on the surface of the substrate. Then opening an Ar flow valve, wherein the flow rate of Ar gas is 50ml/min, controlling the working air pressure in the vacuum chamber to be maintained at about 0.4Pa by adjusting the pumping speed of the molecular pump, and the heating temperature of the chamber is 300 ℃. Then, a direct current power supply is turned on, the arc current is 30A, the bias voltage is-500V, and the sputtering time is 40 min. After deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped. Finally, observing the surface and section microscopic morphology of the deposited coating by using a scanning electron microscope, and finding Ti after deposition₃SiC₂The coating was dense, flat, free of voids (as shown in FIG. 7), and bonded well to the substrate under conditions whereThe thickness of the lower coating layer is about 7.5 μm.

Example 4:

will (Ti, V)₃SiC₂The coating was deposited on the surface of the 316L stainless steel interconnect. First of all (Ti, V)₃SiC₂Bulk target material and commercially available 316L stainless steel alloy. And (2) gradually polishing the alloy matrix by using 400#, 600#, 800#, 1000#, 1200#, 1500# and 2000# metallographic abrasive paper, then respectively ultrasonically cleaning the polished metal connector sample for 15min by using acetone, alcohol and deionized water, and drying the metal connector sample in the air for later use.

The magnetron sputtering equipment is used for depositing a coating on the surface of the alloy, firstly, a sample is hung on a sample rack of the equipment (shown in figure 1), and a stand column of the sample can rotate, and meanwhile, the rotating stand column can revolve with a rotating table. Before the coating is prepared, firstly, the vacuum is pre-pumped to 5X 10^-4Pa to minimize contamination of residual gases during sputtering. After reaching the vacuum degree required by the experiment, high-purity Ar gas with the flow rate of 30ml/min is introduced, and the working air pressure is adjusted to be kept at 0.35 Pa. First using Ar before the start of deposition⁺And cleaning the target material to remove pollutants on the surface of the target material, wherein the cleaning time is 15 min. The sample was then heated to 200 ℃ and held for 15min to allow the temperature of the entire sample to be uniform before sputtering to produce the coating. In the preparation process of the coating, the sputtering power is 0.5kw, and the sputtering time is 2 h. After deposition is finished, the temperature is reduced to room temperature at the speed of 10 ℃/min under the original vacuum condition, and then vacuumizing and pressure removing are stopped.

After the experiment, the microscopic appearance of the surface and the section of the deposited coating is observed by a scanning electron microscope, and after the deposition, (Ti, V)₃SiC₂The coating is compact and flat, has no holes, and is well combined with the substrate, and the thickness of the coating under the condition is about 2.5 mu m. In a fuel cell simulation environment (H)₂SO₄The electro-kinetic potential test is carried out at the concentration of 0.5mol/L and the temperature of 70 ℃), and the corrosion current density of the bipolar plate after the deposition coating is 10 mu A/cm²[ Corrosion potential 0.075V (vs. SCE)]The assembling force is 150N/cm²Under the condition, the contact resistance is 5.7m omega cm²The coating can effectively improve the corrosion resistance of the bipolar plate of the proton exchange membrane fuel cellAnd conductivity properties.

The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.