CN108574107A - Method for Improving Conductivity and Corrosion Resistance of Fuel Cell Bipolar Plate Carbide Coating - Google Patents

Abstract

The present invention relates to improve fuel battery double plates carbide coating conduction and corrosion proof method, it is included in metal bipolar plate surface and is sequentially depositing intermediate metal and metal-carbide coating, then processing is performed etching to coating cated bipolar plates, change the surface texture and constituent of carbide coating, finally through over cleaning, the carbide coating that drying obtains corrosion resistance and electric conductivity improves.Compared with prior art, the present invention uses optimization of the lithographic technique to coating performance on the basis of being coated with coating on metal polar plate, coupling influence when adjusting each parameter size when prepared by coating is avoided, therefore can be applied to further improving to reach the job requirement of fuel cell for fuel battery double plates carbide coating performance.

Description

Method for Improving Conductivity and Corrosion Resistance of Fuel Cell Bipolar Plate Carbide Coating

technical field

The invention belongs to the technical field of fuel cells, in particular to a method for improving the conductivity and corrosion resistance of a carbide coating on a fuel cell bipolar plate.

Background technique

Proton Exchange Membrane Fuel Cell (PEMFC) has been widely used in the fields of transportation, national defense, and electronic products due to its high conversion efficiency, no pollution to the environment, low operating temperature, and long operating life. In the composition structure of proton exchange membrane fuel cell, the bipolar plate occupies most of the space and cost, and the service environment of the fuel cell is a high temperature (60～90℃) containing SO ₄ ^2- , Cl ^- , F ^- plasma ), strongly acidic (pH=1~3) environment, so higher requirements are placed on the physical and chemical properties of the bipolar plate: the ideal bipolar plate material must be a good conductor of electricity and heat, with good resistance It has good corrosion resistance within a certain working temperature and potential range, low density, high strength, and is easy to process and mass produce. Traditional metal materials have good electrical conductivity, thermal conductivity, and excellent mechanical properties. They are suitable for mass production and are the first choice for fuel cell bipolar plate materials. However, metal plates will be severely corroded in the working environment of fuel cells, causing metal poles The precipitation of metal ions such as Cr ⁺ and Ni ⁺ in the plate will lead to the pollution of the proton exchange membrane and the degradation of the catalyst, thereby reducing the service life of the fuel cell, and in the acidic environment, the metal surface is very easy to form a passivation film to increase the contact between the plate and the gas diffusion layer resistance, resulting in a drop in battery output power. Therefore, preparing a corrosion-resistant and high-conductivity coating on the surface of the metal plate is an effective way to improve the performance of the metal plate.

The coatings currently applied to metal bipolar plates mainly include graphite coatings, noble metal coatings, conductive polymer coatings, and cermet coatings. Although graphite coating and noble metal coating have good chemical stability and electrical conductivity, the deposition rate of the former is too slow, resulting in high time cost, and the latter is not suitable for mass production due to its high material cost; conductive polymers The chemical properties of the coating are not very stable, and the degree of bonding with the substrate cannot meet the requirements. Cermet coatings, especially metal carbide coatings, have been widely used in actual production due to their excellent corrosion resistance and electrical conductivity, fast deposition rate, and low preparation cost. Layer performance is also a research hotspot at present. The optimization of corrosion resistance and electrical conductivity of metal carbide coatings can be achieved mainly through the following three approaches: (1) Change the metal materials (such as Cr, Ti, Zr, Nb, etc.) The ratio of each component in the metal carbide with the best performance; (2) doping other elements (such as N or other metals) in the carbide coating; (3) changing the surface structure of the coating by physical or chemical methods and Composition. The first two methods need to readjust the parameters to prepare a new carbide coating, while the last method can directly improve the performance of the existing carbide coating, which can save a lot of time and material costs. Among them, the etching process is an effective method to improve the performance of the coating by changing the surface structure of the coating, including wet etching and dry etching. The etching process mainly includes the following three steps: the diffusion of the reactant to the reaction surface, the conduction of the chemical reaction, and the stripping of the reaction product. As shown in Figure 1 and Figure 2, the surface structure and composition of the metal carbide coating are changed by etching, part of the metal elements in the coating are removed, the escape of metal ions during service is reduced, and more conductive particles Exposed on the surface, thereby effectively improving the electrical conductivity and corrosion resistance of the coating.

Patent Publication No. CN102800871A discloses a method for preparing a carbon-chromium step coating by unbalanced magnetron sputtering technology. By adjusting a series of process parameters to change the composition of the coating, the corrosion resistance of the metal bipolar plate is further improved. and electrical conductivity. Patent Publication No. CN101626082B proposes to use chemical etching to remove the passivation film and deposit a conductive ceramic layer before surface modification of the sheet, and then add a silver-plated layer and coat a silver-plated protective film on the surface. Patent Publication No. CN101918619A discloses a method for manufacturing a highly conductive surface, including depositing corrosion-resistant particles, conductive particles or The metal containing these particles then exposes the particles to increase the conductivity of the metal surface. Patent Publication No. CN103050712A discloses a method for improving the corrosion resistance of chromium carbide-plated stainless steel bipolar plates, that is, degreasing and degreasing the coated stainless steel bipolar plates and placing them in a rare earth passivation solution KMnO ₄ + Ce(NO ₃ ) ₃ ·6H ₂ +Mg(NO ₃ ) ₂ treatment for a period of time can significantly reduce the corrosion current density of the bipolar plate. Patent Publication No. CN106929856A uses hydrofluoric acid to etch the nickel surface in a water bath to increase the surface roughness and thereby improve the hydrophobicity of the surface. Patent Publication No. CN102051598A discloses an ultrasonic immersion etching method using a mixture of hydrofluoric acid and nitric acid to improve the bonding force between titanium and titanium nitride films. However, the methods for improving the performance of metal carbide coatings in the above-mentioned published patents are relatively complicated, which increases the cost of coating preparation, and does not directly use the etching process to improve the corrosion resistance and conductivity of metal carbide coatings. Make improvements.

Contents of the invention

The object of the present invention is to provide a simple and effective method for improving the corrosion resistance and electrical conductivity of the metal carbide coating on the fuel cell bipolar plate by etching to overcome the above-mentioned defects in the prior art.

The purpose of the present invention can be achieved through the following technical solutions:

The method for improving the conductivity and corrosion resistance of the carbide coating on the fuel cell bipolar plate comprises depositing a metal transition layer and a metal carbide coating in sequence on the surface of the metal bipolar plate, and then engraving the coated bipolar plate Corrosion treatment to change the surface structure and composition of the carbide coating, and finally after cleaning and drying to obtain a carbide coating with improved corrosion resistance and electrical conductivity, the specific steps are as follows:

1) Metal bipolar plate pretreatment: place the metal bipolar plate in ethanol and acetone in sequence, ultrasonically clean and dry;

2) Coating preparation: depositing a metal transition layer and a metal carbide coating on the surface of the metal bipolar plate;

3) Coating etching: fully immerse the bipolar plate in the pre-configured chemical etching solution for wet etching or dry etching in etching equipment;

4) Take out the etched metal bipolar plate, wash and dry to obtain a carbide coating with improved corrosion resistance and electrical conductivity.

The material of the metal bipolar plate includes one of stainless steel, aluminum alloy or magnesium alloy, and the thickness is 0.1-2mm.

The metal transition layer is composed of one metal among chromium (Cr), titanium (Ti), zirconium (Zr), niobium (Nb) and molybdenum (Mo), and the thickness is 5-100nm.

The metal carbide coating is a stepped coating or a continuous coating with a thickness of 10-300nm.

The metal carbide coated by the metal carbide coating includes one of chromium carbide (Cr ₃ C ₂ ), titanium carbide (TiC), zirconium carbide (ZrC), niobium carbide (NbC) or molybdenum carbide (MoC) or more.

The metal carbide coating is prepared by magnetron sputtering, chemical vapor deposition, multi-arc ion plating or electron beam evaporation.

Hydrofluoric acid solution or a mixture of hydrofluoric acid and nitric acid is used for wet etching, the etching temperature is 10-70°C, and the etching time is 5s-20min. Through the chemical reaction between the etching solution and the coating, the conductive metal particles in the coating are exposed on the coating surface, reducing the metal content inside the coating, and effectively improving the corrosion resistance and conductivity of the coating. When the concentration of the etchant is too high or the etching time is too long, the coating will be severely damaged and the substrate will be exposed. If the temperature is too high, the etchant will volatilize, and it is difficult to control the etching speed. If the etchant concentration is too low, the temperature is too low or the etching time is too short, and the etching rate is too low, the influence on the composition of the coating is small and the improvement effect cannot be achieved.

The mass concentration of the hydrofluoric acid solution is 0.5%-10%, the mass concentration of hydrofluoric acid in the mixed solution of hydrofluoric acid and nitric acid is 0.5%-10%, and the mass concentration of nitric acid is 0.1%-20%.

The process gas used in dry etching includes one or more of chlorine, carbon tetrafluoride, carbon tetrachloride, hydrogen or oxygen. The gas flow rate is 10-500sccm, the pressure is 10-1000Pa, and the etching time is 5min-1h. The reactive gas is activated into active particles under the action of high-energy discharge reaction. These particles diffuse to the surface of the coating to react and form volatile substances to remove metal. If the etching time is too long, the coating will be damaged, and if it is too short, it will not be able to achieve The effect of performance improvement.

Compared with the prior art, the present invention uses wet etching or dry etching to change the surface structure and component composition of the coating on the basis of one or more layers of carbide coatings that have been plated, thereby increasing the coating thickness. The surface roughness of the layer, thereby further improving the corrosion resistance and electrical conductivity of the carbide coating. Compared with some existing metal carbide coating preparation and performance improvement methods, the present invention greatly reduces the execution complexity of the process and reduces the coating preparation while improving the corrosion resistance and electrical conductivity of the carbide coating. cost, and has little effect on the mechanical properties of metal plates. The present invention uses etching technology to optimize the performance of the coating on the basis of coating on the metal plate, thereby avoiding the coupling effect when adjusting the size of each parameter during coating preparation, so it can be applied to fuel cell bipolar The performance of the plate carbide coating is further improved to meet the working requirements of the fuel cell.

Description of drawings

Fig. 1 is the schematic diagram of untreated metal pole plate;

Fig. 2 is the schematic diagram of the metal pole plate after etching;

Fig. 3 is the contact resistance of the metal bipolar plate after etching under different lengths of time in the present invention;

Fig. 4 is the contact resistance of the metal bipolar plate before and after etching at different concentrations according to the present invention.

In the figure, 1-metal plate, 2-metal transition layer, 3-metal carbide layer, 4-metal carbide particles, 5-metal particles, 6-metal ions generated by etching.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Example 1:

The titanium carbide coating is prepared on the surface of the stainless steel bipolar plate as the substrate, and the process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Hang the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace chamber, keep the turret speed at 4r/min, and evacuate to the background vacuum of 3*10 ^-5 After Torr, fill with argon and keep the working pressure at 4*10 ^-4 Torr, apply a bias voltage of -500V to the stainless steel substrate, so that the ions continuously bombard the surface of the substrate, clear the passivation layer on the surface, and clean for 30 minutes;

3) Introduce 20 sccm of argon as a protective gas, and 20 sccm of reaction gas acetylene for 30 minutes, keep the substrate bias at -100V, turn on the titanium target current, and deposit a titanium carbide coating on the surface of the stainless steel plate by reactive sputtering;

4) Turn off the target current and the air vent, and cool for 20 minutes to obtain the desired titanium carbide coating.

As shown in Figure 3, the initial contact resistance of the metal bipolar plate is 7.84mΩ·cm ² , and the contact resistance increases to 31.07mΩ after being corroded for 1 hour at a constant potential of 1.6V (vs. SHE) in sulfuric acid with pH=3 • cm ² .

Example 2:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 6% hydrofluoric acid for 5 seconds, the plate was taken out, cleaned and dried to obtain a titanium carbide coating with improved properties.

As shown in FIG. 3 , the initial contact resistance of the metal bipolar plate is 2.33 mΩ·cm ² .

Example 3:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 6% hydrofluoric acid for 10 seconds, the plate was taken out, cleaned and dried to obtain a titanium carbide coating with improved properties.

As shown in FIG. 3 , the initial contact resistance of the metal bipolar plate is 2.51 mΩ·cm ² .

Example 4:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 6% hydrofluoric acid for 20 seconds, take out the plate, clean it and dry it to obtain a titanium carbide coating with improved properties.

As shown in FIG. 3 , the initial contact resistance of the metal bipolar plate is 2.72 mΩ·cm ² .

Example 5:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 6% hydrofluoric acid for 30 seconds, the plate was taken out, cleaned and dried to obtain a titanium carbide coating with improved properties.

As shown in FIG. 3 , the initial contact resistance of the metal bipolar plate is 2.73 mΩ·cm ² .

Embodiment 6:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 2% hydrofluoric acid for 10 seconds, take out the plate, clean it and dry it to obtain a titanium carbide coating with improved properties.

As shown in Figure 4, the initial contact resistance of the metal bipolar plate is 2.77mΩ·cm ² , and the contact resistance increases to 15.82mΩ after being corroded for 1 hour at a constant potential of 1.6V (vs. SHE) in sulfuric acid with pH=3 • cm ² .

Embodiment 7:

The stainless steel bipolar plate is used as the substrate, and the titanium carbide coating is prepared on the surface, and the corrosion resistance and conductivity of the titanium carbide coating are improved by wet etching. The process is as follows:

1) Plate pretreatment: use deionized water, acetone, and absolute ethanol in sequence to ultrasonically clean the surface of the stainless steel bipolar plate and dry it;

2) Suspend the pretreated stainless steel bipolar plate on the planetary turret platform in the unbalanced magnetron sputtering ion plating furnace cavity, vacuumize to the background vacuum, fill it with argon, and apply bias on the stainless steel substrate. pressure, so that the ions continue to bombard the surface of the substrate, and the cleaning time is 30 minutes;

3) Pass the working gas and the reaction gas into the vacuum container at the same time, and deposit the titanium carbide coating on the surface of the stainless steel plate by sputtering the metal target, and the sputtering time is 30 minutes;

4) After immersing the metal bipolar plate coated with titanium carbide coating in 4% hydrofluoric acid for 10 seconds, the plate was taken out, cleaned and dried to obtain a titanium carbide coating with improved properties.

As shown in Figure 4, the initial contact resistance of the metal bipolar plate is 2.32mΩ·cm ² , and the contact resistance increases to 17.16mΩ·cm ² after being corroded for 1 hour at a constant potential of 1.6V (vs. SHE) in sulfuric acid with pH=3 .

The above-mentioned examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are provided, wherein under the conditions of Example 3-after 6% hydrofluoric acid etching for 10s, the metal carbide coating The layer has the best corrosion resistance and electrical conductivity, the contact resistance before corrosion is 2.51mΩ·cm ² , and the contact resistance after corrosion is 6.72mΩ·cm ² , both of which meet the requirement that the contact resistance of fuel cell bipolar plates is less than 10mΩ·cm ² Require.

Embodiment 8:

The structure of the metal pole plate without wet etching or dry etching is shown in Figure 1, including the metal pole plate 1, the metal transition layer 2 and the metal carbide layer 3 coated on the metal pole plate 1, in The metal carbide layer 3 contains metal carbide particles 4 and metal particles 5 .

The structure of the metal pole plate by wet etching or dry etching is shown in Figure 2. Compared with Figure 1, after etching, most of the metal particles 5 in the metal carbide layer 3 form metal ions 6 and Enter the etching solution or form volatile substances and be removed, causing the conductive metal particles to be exposed on the surface of the coating, thereby improving the conductivity. However, metal carbide particles 4 are less affected by etching, resulting in an increase in the content of metal carbides in the coating, further improving the corrosion resistance of the coating.

Embodiment 9:

The method for improving the conductivity and corrosion resistance of the carbide coating on the fuel cell bipolar plate comprises depositing a metal transition layer and a metal carbide coating in sequence on the surface of the metal bipolar plate, and then engraving the coated bipolar plate Corrosion treatment to change the surface structure and composition of the carbide coating, and finally after cleaning and drying to obtain a carbide coating with improved corrosion resistance and electrical conductivity, the specific steps are as follows:

1) Metal bipolar plate pretreatment: place the metal bipolar plate in ethanol and acetone in sequence, ultrasonically clean and dry;

2) Coating preparation: Deposit a metal transition layer and a metal carbide coating on the surface of the metal bipolar plate, wherein the metal carbide coating is a stepped coating with a thickness of 10nm, and the coated metal carbide includes chromium carbide ( _Cr3 C ₂ ), titanium carbide (TiC), prepared by magnetron sputtering;

3) Coating etching: The bipolar plate is completely immersed in a pre-configured hydrofluoric acid solution with a mass concentration of 0.5% for wet etching, the etching temperature is 10°C, and the etching time is 20 minutes;

4) Take out the etched metal bipolar plate, wash and dry to obtain a carbide coating with improved corrosion resistance and electrical conductivity.

Example 10:

The method for improving the conductivity and corrosion resistance of the carbide coating on the fuel cell bipolar plate comprises depositing a metal transition layer and a metal carbide coating in sequence on the surface of the metal bipolar plate, and then engraving the coated bipolar plate Corrosion treatment to change the surface structure and composition of the carbide coating, and finally after cleaning and drying to obtain a carbide coating with improved corrosion resistance and electrical conductivity, the specific steps are as follows:

1) Metal bipolar plate pretreatment: place the metal bipolar plate in ethanol and acetone in sequence, ultrasonically clean and dry;

2) Coating preparation: Deposit a metal transition layer and a metal carbide coating on the surface of the metal bipolar plate, wherein the metal carbide coating is a stepped coating with a thickness of 80nm, and the coated metal carbide is zirconium carbide (ZrC) , prepared by chemical vapor deposition;

3) Coating etching: the bipolar plate is completely immersed in a chemical etching solution composed of 10% hydrofluoric acid and 0.1% nitric acid for wet etching;

4) Take out the etched metal bipolar plate, wash and dry to obtain a carbide coating with improved corrosion resistance and electrical conductivity.

Example 11:

The method for improving the conductivity and corrosion resistance of the carbide coating on the fuel cell bipolar plate comprises depositing a metal transition layer and a metal carbide coating in sequence on the surface of the metal bipolar plate, and then engraving the coated bipolar plate Corrosion treatment to change the surface structure and composition of the carbide coating, and finally after cleaning and drying to obtain a carbide coating with improved corrosion resistance and electrical conductivity, the specific steps are as follows:

1) Metal bipolar plate pretreatment: place the metal bipolar plate in ethanol and acetone in sequence, ultrasonically clean and dry;

2) Coating preparation: deposit a metal transition layer and a metal carbide coating on the surface of the metal bipolar plate, wherein the metal carbide coating is a continuous coating with a thickness of 200nm, and the coated metal carbide is niobium carbide. Prepared by arc ion plating;

3) Coating etching: the bipolar plate is placed in an etching device for dry etching, the process gas used is chlorine gas, the gas flow rate is 10 sccm, the air pressure is 10 Pa, and the etching time is 1 h;

4) Take out the etched metal bipolar plate, wash and dry to obtain a carbide coating with improved corrosion resistance and electrical conductivity.

Example 12:

The method for improving the conductivity and corrosion resistance of the carbide coating on the fuel cell bipolar plate comprises depositing a metal transition layer and a metal carbide coating in sequence on the surface of the metal bipolar plate, and then engraving the coated bipolar plate Corrosion treatment to change the surface structure and composition of the carbide coating, and finally after cleaning and drying to obtain a carbide coating with improved corrosion resistance and electrical conductivity, the specific steps are as follows:

1) Metal bipolar plate pretreatment: place the metal bipolar plate in ethanol and acetone in sequence, ultrasonically clean and dry;

2) Coating preparation: Deposit a metal transition layer and a metal carbide coating on the surface of the metal bipolar plate, wherein the metal carbide coating is a continuous coating with a thickness of 300nm, and the coated metal carbide is molybdenum carbide (MoC) , prepared by electron beam evaporation;

3) Coating etching: place the bipolar plate in the etching equipment for dry etching, the process gas used is carbon tetrafluoride and carbon tetrachloride, the gas flow rate is 500sccm, the air pressure is 1000Pa, the etching time 5min;

4) Take out the etched metal bipolar plate, wash and dry to obtain a carbide coating with improved corrosion resistance and electrical conductivity.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims (8)

1. improving fuel battery double plates carbide coating conduction and corrosion proof method, which is characterized in that this method is included in Metal bipolar plate surface is sequentially depositing intermediate metal and metal-carbide coating, is then carried out to coating cated bipolar plates Etching processing changes the surface texture and constituent of carbide coating, finally through over cleaning, drying obtain corrosion resistance and The carbide coating that electric conductivity improves.

2. improvement fuel battery double plates carbide coating conduction according to claim 1 and corrosion proof method, special Sign is that this method specifically uses following steps：

1) metal double polar plates pre-process：Metal double polar plates are sequentially placed into ethyl alcohol, in acetone, using being cleaned by ultrasonic and dry；

2) prepared by coating：In metal bipolar plate surface deposited metal transition zone and metal-carbide coating；

3) coating etches：Bipolar plates are completely immersed in chemical etching solution and carry out wet etching or be placed in etching apparatus to do Method etches；

4) metal double polar plates and cleaning, drying after etching are taken out and obtain the carbide coating that corrosion resistance and electric conductivity improve.

3. improvement fuel battery double plates carbide coating conduction according to claim 2 and corrosion proof method, special Sign is that the metal-carbide coating is steps coating or continuity coating, thickness 10-300nm.

4. improvement fuel battery double plates carbide coating conduction according to claim 2 and corrosion proof method, special Sign is that the metal carbides of the metal-carbide coating coating include chromium carbide (Cr₃C₂), titanium carbide (TiC), zirconium carbide (ZrC), one or more in niobium carbide (NbC) or molybdenum carbide (MoC).

5. improvement fuel battery double plates carbide coating conduction according to claim 2 and corrosion proof method, special Sign is that the metal-carbide coating passes through magnetron sputtering method, chemical vapor deposition, multi-arc ion coating or electron beam evaporation system It is standby to obtain.

6. improvement fuel battery double plates carbide coating conduction according to claim 2 and corrosion proof method, special Sign is that wet etching is using hydrofluoric acid solution or the mixed liquor of hydrofluoric acid and nitric acid, and etching temperature is 10-70 DEG C, etching Time is 5s-20min.

7. improvement fuel battery double plates carbide coating conduction according to claim 6 and corrosion proof method, special Sign is, the mass concentration of the hydrofluoric acid solution is 0.5%-10%, hydrofluoric acid in the mixed liquor of the hydrofluoric acid and nitric acid Mass concentration be 0.5%-10%, the mass concentration of nitric acid is 0.1%-20%.

8. improvement fuel battery double plates carbide coating conduction according to claim 2 and corrosion proof method, special Sign is, the process gas that dry etching uses include one kind in chlorine, carbon tetrafluoride, carbon tetrachloride, hydrogen or oxygen or It is several, gas flow 10-500sccm, air pressure 10-1000Pa, etch period 5min-1h.