阅读说明：本技术 一种金属双极板高导电耐蚀防护涂层及其制备方法与应用 (Metal bipolar plate high-conductivity corrosion-resistant protective coating and preparation method and application thereof ) 是由 李�昊 汪爱英 张栋 柯培玲 刘林林 于 2019-11-07 设计创作，主要内容包括：本发明公开了一种金属双极板高导电耐蚀防护涂层及其制备方法与应用。所述金属双极板高导电耐蚀防护涂层的制备方法包括：以铬靶为靶材,采用高功率脉冲磁控溅射技术在所述金属双极板表面沉积铬过渡层；以及,以石墨靶为靶材,采用直流磁控溅射技术在所述铬过渡层表面沉积非晶碳层,获得金属双极板高导电耐蚀防护涂层；其中,所述直流磁控溅射技术采用的工艺条件包括：溅射源中心磁场强度为40～60mT,边缘磁场强度为10～20mT,电源功率为0.8～1.0kW。本发明提供的铬过渡层表面光滑内部结构致密,可以有效提高膜基结合强度；同时通过优化非晶碳层的制备工艺,使得非晶碳层兼具良好的导电性以及优异的耐蚀性,能够实现对金属双极板的长效防护。(The invention discloses a high-conductivity corrosion-resistant protective coating for a metal bipolar plate and a preparation method and application thereof. The preparation method of the metal bipolar plate high-conductivity corrosion-resistant protective coating comprises the following steps: depositing a chromium transition layer on the surface of the metal bipolar plate by using a high-power pulse magnetron sputtering technology by taking a chromium target as a target material; depositing an amorphous carbon layer on the surface of the chromium transition layer by using a graphite target as a target material and adopting a direct-current magnetron sputtering technology to obtain a high-conductivity corrosion-resistant protective coating of the metal bipolar plate; wherein, the process conditions adopted by the direct current magnetron sputtering technology comprise: the central magnetic field intensity of the sputtering source is 40-60 mT, the edge magnetic field intensity is 10-20 mT, and the power supply power is 0.8-1.0 kW. The chromium transition layer provided by the invention has a smooth surface and a compact internal structure, and can effectively improve the film-substrate bonding strength; meanwhile, by optimizing the preparation process of the amorphous carbon layer, the amorphous carbon layer has good conductivity and excellent corrosion resistance, and long-acting protection on the metal bipolar plate can be realized.)

1. A preparation method of a metal bipolar plate high-conductivity corrosion-resistant protective coating is characterized by comprising the following steps:

providing a metal bipolar plate;

depositing a chromium transition layer on the surface of the metal bipolar plate by using a high-power pulse magnetron sputtering technology by taking a chromium target as a target material;

depositing an amorphous carbon layer on the surface of the chromium transition layer by using a graphite target as a target material and adopting a direct-current magnetron sputtering technology to obtain a high-conductivity corrosion-resistant protective coating of the metal bipolar plate;

wherein, the process conditions adopted by the direct current magnetron sputtering technology comprise: the central magnetic field intensity of the sputtering source is 40-60 mT, the edge magnetic field intensity is 10-20 mT, and the power supply power is 0.8-1.0 kW.

2. The preparation method according to claim 1, wherein the process conditions adopted by the direct current magnetron sputtering technology further comprise: the chamber pressure is 1.7 to 2.2mTorr, and the bias pressure is-50V to-250V.

3. The preparation method according to claim 1, wherein the high power pulse magnetron sputtering technique adopts process conditions including: the frequency of the sputtering power supply is 400-600 Hz, the pulse width is 100-200 mus, the pulse voltage is 800-1000V, and the power is 2.5-4 KW.

4. The preparation method according to claim 3, wherein the high power pulse magnetron sputtering technique further comprises the following process conditions: the chamber pressure is 1.7 to 2.2mTorr, and the bias pressure is-50V to-100V.

5. The method of claim 1, further comprising: firstly, etching the surface of the metal bipolar plate, and then forming the chromium transition layer on the surface of the metal bipolar plate.

6. The production method according to claim 5, wherein the etching treatment includes: and performing etching treatment on the metal bipolar plate for 30-60 min at room temperature by adopting an Ar ion etching method, wherein the etching treatment adopts the following process conditions: the vacuum chamber has a pressure of 2.0 × 10^-5Below Torr, argonThe gas flow is 40-100 sccm, and the bias voltage is-150 to-450V;

preferably, the Ar ion etching method includes glow etching and/or ion beam etching.

7. The method of claim 1, wherein: the metal bipolar plate comprises any one of a stainless steel bipolar plate and a titanium alloy bipolar plate.

8. The highly conductive corrosion-resistant protective coating for the metal bipolar plate prepared by the method of any one of claims 1 to 7, wherein the protective coating comprises a chromium transition layer and an amorphous carbon layer which are sequentially formed on the metal bipolar plate; preferably, the thickness of the chromium transition layer is 100-200 nm; preferably, the thickness of the amorphous carbon layer is 500 to 800 nm.

9. Use of the highly conductive corrosion-resistant protective coating for metal bipolar plates according to claim 8 in the field of substrate surface protection.

10. A material comprising a matrix, characterized in that: the substrate is further provided with the metal bipolar plate high-conductivity corrosion-resistant protective coating of claim 8.

Technical Field

The invention belongs to the technical field of surface engineering protection, and particularly relates to a high-conductivity corrosion-resistant protective coating for a metal bipolar plate, and a preparation method and application thereof.

Background

Proton Exchange Membrane Fuel Cells (PEMFCs) are a new type of energy source that can convert hydrogen energy directly into electrical energy. The novel energy-saving power supply has the advantages of quick start, relatively low working temperature, quick response to various environments, no pollution, high energy efficiency and the like, and has good application prospects in the aspects of new energy automobiles, fixed and portable power supplies. One cell unit of a proton exchange membrane fuel cell is generally composed of a bipolar plate (BPP), a Membrane Electrode (MEA), a gasket, and an end plate. In many assemblies, the bipolar plates account for 80% of the total mass, almost the entire volume, and about 18-28% of the manufacturing cost of the fuel cell. Bipolar plates are key functional components in a pem fuel cell stack and serve the primary functions of conducting electrons, distributing chemical fuel, separating individual cells, supporting the membrane electrodes, and facilitating water management within the cells. Therefore, it must satisfy the requirements of easy processing and forming, electrochemical corrosion resistance, low interface resistance, low cost, etc. At present, the traditional fuel cell widely uses graphite bipolar plates, but the volume is large, the strength is low, and the large-scale use is restricted. The metal plate with excellent performances such as high electrical conductivity, high thermal conductivity, high mechanical strength, low stamping cost, low gas permeability and the like is expected to replace graphite to become a main material of the bipolar plate.

The operating environment of the pem fuel cell is typically an acidic (pH 2-3), warm and humid (65-90 ℃) environment. Under high temperature, the acidic corrosive medium can generate a passivation layer on the surface of the metal bipolar plate, so that the Interface Contact Resistance (ICR) between the metal bipolar plate and Gas Diffusion Layers (GDLs) is increased; on the other hand, metallic bipolar plates are easily producedSevere corrosion, both of which affect the output power of the battery, resulting in rapid degradation of the battery performance. The deposition of the protective coating on the surface of the metal bipolar plate is an effective means for improving the surface conductivity and the corrosion resistance of the metal bipolar plate. Commonly used protective coatings are noble metal coatings, metal nitride or carbide coatings, conductive polymer coatings, and the like. The amorphous carbon coating is a coating composed of diamond phases sp³And graphitic phase sp²Hybrid-formed mixed structure coatings have many excellent performances due to the excellent chemical inertness of carbon elements and the special mechanism of amorphous carbon, and have attracted much attention in recent years for the application of amorphous carbon coatings in the surface protective coatings of metal bipolar plates. However, when the amorphous carbon coating is sp³When the content is mainly, the corrosion resistance is excellent but the conductivity is poor, and when the coating is sp²When the structure is mainly, the electric conductivity is excellent but the corrosion resistance is poor, so that the comprehensive performance of the amorphous carbon coating in the aspects of electric conductivity and corrosion resistance is still not ideal at present, and the application of the amorphous carbon coating on the surface of the metal bipolar plate is limited. Therefore, the controllable preparation of the amorphous carbon coating with high conductivity and excellent corrosion resistance is the key for promoting the application of the amorphous carbon coating on the surface of the metal bipolar plate, thereby improving the working efficiency and prolonging the service life of the proton exchange membrane fuel cell.

Disclosure of Invention

The invention mainly aims to provide a high-conductivity corrosion-resistant protective coating for a metal bipolar plate, and a preparation method and application thereof, so as to overcome the defects of the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention comprises the following steps:

the embodiment of the invention provides a preparation method of a metal bipolar plate high-conductivity corrosion-resistant protective coating, which comprises the following steps:

providing a metal bipolar plate;

depositing a chromium transition layer on the surface of the metal bipolar plate by using a high-power pulse magnetron sputtering technology by taking a chromium target as a target material;

depositing an amorphous carbon layer on the surface of the chromium transition layer by using a graphite target as a target material and adopting a direct-current magnetron sputtering technology to obtain a high-conductivity corrosion-resistant protective coating of the metal bipolar plate;

wherein, the process conditions adopted by the direct current magnetron sputtering technology comprise: the central magnetic field intensity of the sputtering source is 40-60 mT, the edge magnetic field intensity is 10-20 mT, and the power supply power is 0.8-1.0 kW.

The embodiment of the invention also provides the high-conductivity corrosion-resistant protective coating for the metal bipolar plate, which is prepared by the method, and the protective coating comprises a chromium transition layer and an amorphous carbon layer which are sequentially formed on the metal bipolar plate.

The corrosion current density of the protective coating provided by the invention is less than 5 multiplied by 10 under the standard working voltage of 0.6V^-8A/cm²The contact resistance in a deposition state is less than 7m omega cm²Contact resistance is less than 10m omega cm after 24h of corrosion². The invention adopts high-power pulse magnetron sputtering technology, and has the technical characteristics of improving the ionization rate, refining crystal grains, and ensuring that the prepared coating has smooth surface and compact internal structure.

The embodiment of the invention also provides application of the high-conductivity corrosion-resistant protective coating for the metal bipolar plate in the field of substrate surface protection.

The embodiment of the invention also provides a material which comprises a substrate, wherein the substrate is also provided with the high-conductivity corrosion-resistant protective coating of the metal bipolar plate.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention adopts high-power pulse magnetic control to obtain the chromium transition layer with smooth surface and compact internal structure, can effectively improve the film-substrate bonding strength, and ensures that the surface of the amorphous carbon layer growing on the surface of the chromium transition layer is smooth and compact in structure;

(2) the invention adopts the direct current magnetron sputtering technology as the preparation method of the amorphous carbon coating of the metal bipolar plate, optimizes two core parameters of the magnetic field intensity and the sputtering power of a sputtering source on the basis, and ensures that the prepared amorphous carbon coating has excellent conductivity and the coating has excellent corrosion resistance and protection performance under the acidic high-temperature environment.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is an XPS test result of an amorphous carbon layer prepared in example 1 of the present invention;

FIG. 2 is a graph showing the results of corrosion performance tests of example 1 of the present invention and comparative examples 1 to 2;

FIG. 3 is a graph showing the results of the contact resistance test of example 1 of the present invention and comparative examples 1 to 2;

FIG. 4 is photographs before and after etching of examples 1 to 3 of the present invention and comparative examples 1 to 2;

FIGS. 5a-5b are surface topography maps for coatings of example 1 of the present invention and comparative example 3.

Detailed Description

In view of the defects of the prior art, the inventor of the present invention has made extensive research and practice to provide a technical solution of the present invention, which mainly aims at the problem that the application of the existing amorphous carbon coating on the surface of a metal bipolar plate has insufficient comprehensive performance, and provides a method for preparing a high-conductivity corrosion-resistant protective coating on the surface of a metal bipolar plate.

One aspect of the embodiment of the invention provides a preparation method of a metal bipolar plate high-conductivity corrosion-resistant protective coating, which is characterized by comprising the following steps:

providing a metal bipolar plate;

depositing a chromium transition layer on the surface of the metal bipolar plate by using a high-power pulse magnetron sputtering technology by taking a chromium target as a target material;

depositing an amorphous carbon layer on the surface of the chromium transition layer by using a graphite target as a target material and adopting a direct-current magnetron sputtering technology to obtain a high-conductivity corrosion-resistant protective coating of the metal bipolar plate;

wherein, the process conditions adopted by the direct current magnetron sputtering technology comprise: the central magnetic field intensity of the sputtering source is 40-60 mT, the edge magnetic field intensity is 10-20 mT, and the power supply power is 0.8-1.0 kW.

Further, the process conditions adopted by the direct current magnetron sputtering technology further include: the chamber pressure is 1.7 to 2.2mTorr, and the bias pressure is-50V to-250V.

Further, the high power pulse magnetron sputtering technology adopts the following process conditions: the frequency of the sputtering power supply is 400-600 Hz, the pulse width is 100-200 mus, the pulse voltage is 800-1000V, and the power is 2.5-4 KW.

Further, the process conditions adopted by the high-power pulse magnetron sputtering technology further include: the chamber pressure is 1.7 to 2.2mTorr, and the bias pressure is-50V to-100V.

Further, the method further comprises: firstly, etching the surface of the metal bipolar plate, and then forming the chromium transition layer on the surface of the metal bipolar plate.

In some specific embodiments, the method comprises:

and performing etching treatment on the metal bipolar plate for 30-60 min at room temperature by adopting an Ar ion etching method, wherein the etching treatment adopts the following process conditions: the vacuum chamber has a pressure of 2.0 × 10^-5The argon flow is 40 to 100sccm and the bias is-150 to-450V below Torr.

Further, the Ar ion etching method comprises glow etching and/or ion beam etching.

Further, the metal bipolar plate includes any one of a stainless steel bipolar plate and a titanium alloy bipolar plate, and is not limited thereto.

Another aspect of the embodiments of the present invention provides a highly conductive corrosion-resistant protective coating for a metal bipolar plate, which is prepared by the foregoing method, and the protective coating includes a chromium transition layer and an amorphous carbon layer sequentially formed on the metal bipolar plate.

Furthermore, the thickness of the chromium transition layer is 100-200 nm.

Further, the thickness of the amorphous carbon layer is 500-800 nm.

In another aspect of the embodiment of the invention, the application of the highly conductive corrosion-resistant protective coating for the metal bipolar plate in the field of substrate surface protection is provided.

Another aspect of the embodiment of the present invention provides a material, which includes a substrate, and the substrate is further provided with the above-mentioned highly conductive corrosion-resistant protective coating for the metal bipolar plate.

The technical solutions of the present invention are further described in detail below with reference to several preferred embodiments and the accompanying drawings, which are implemented on the premise of the technical solutions of the present invention, and a detailed implementation manner and a specific operation process are provided, but the scope of the present invention is not limited to the following embodiments.