阅读说明：本技术 一种防腐导电涂层制备方法、结构以及燃料电池极板 (Preparation method and structure of anticorrosive conductive coating and fuel cell polar plate ) 是由 陆娇娇 刘智亮 张威 肖彪 于 2020-12-25 设计创作，主要内容包括：本发明公开一种防腐导电涂层制备方法、结构以及燃料电池极板,该制备方法包括以下步骤：对基材进行清洗,并将基材置于真空室中；对真空室进行抽真空；对真空室进行加热；利用等离子对过渡金属靶或金属氧化物靶材进行至少两次溅射,在基材上生成至少两层功能涂层,该功能涂层为过渡金属涂层或金属化合物涂层；利用等离子对贵金属靶材进行溅射,形成贵金属涂层。该涂层结构包括贵金属涂层和至少两层功能涂层,所述功能涂层位于基材和贵金属涂层之间；所述功能涂层由过渡金属或金属化合物制成。本发明不仅能够获得具有优异的结合力、耐腐蚀性能以及导电性能的涂层,而且涂层中的贵金属用量较少,有利于降低制造成本。(The invention discloses a preparation method and a structure of an anticorrosive conductive coating and a fuel cell polar plate, wherein the preparation method comprises the following steps: cleaning a substrate, and placing the substrate in a vacuum chamber; vacuumizing the vacuum chamber; heating the vacuum chamber; sputtering a transition metal target or a metal oxide target for at least two times by using plasma to generate at least two functional coatings on a base material, wherein the functional coatings are transition metal coatings or metal compound coatings; and sputtering the noble metal target material by using plasma to form the noble metal coating. The coating structure comprises a noble metal coating and at least two functional coatings, wherein the functional coatings are positioned between a base material and the noble metal coating; the functional coating is made of a transition metal or a metal compound. The invention can obtain the coating with excellent binding force, corrosion resistance and electrical conductivity, and the precious metal in the coating is less in use amount, thereby being beneficial to reducing the manufacturing cost.)

1. The preparation method of the anticorrosive conductive coating is characterized by comprising the following steps of:

(1) cleaning a substrate, and placing the substrate in a vacuum chamber;

(2) vacuumizing the vacuum chamber;

(3) heating the vacuum chamber;

(4) sputtering a transition metal target or a metal oxide target for at least two times by using plasma to generate at least two functional coatings on a base material, wherein the functional coatings are transition metal coatings or metal compound coatings;

(5) and sputtering the noble metal target material by using plasma to form the noble metal coating.

2. The method for preparing the anticorrosive conductive coating according to claim 1, wherein in the step (2), after the vacuum pumping, the vacuum degree of the vacuum chamber is not less than 5 x10^-3Pa。

3. The method for preparing an anticorrosive conductive coating according to claim 1, wherein in step (3), after heating, the temperature of the vacuum chamber is 80-250 ℃.

4. The method for preparing an anticorrosive conductive coating according to claim 1, wherein in step (4), the substrate is plasma-cleaned with argon ions for 1 to 30 minutes before sputtering the target.

5. The method for preparing an anticorrosive conductive coating according to claim 4, characterized in that bias sputtering is started when the working pressure in the vacuum chamber reaches 0.01 to 1 Pa.

6. The method for preparing the anticorrosive conductive coating according to claim 1, wherein in the step (4), before sputtering the target material each time, an auxiliary sputtering gas with a concentration of more than 99% is introduced, wherein the auxiliary sputtering gas is nitrogen or acetylene or methane.

7. An anticorrosion conductive coating structure is characterized by comprising a noble metal coating and at least two functional coatings, wherein the functional coatings are positioned between a base material and the noble metal coating;

the functional coating is made of a transition metal or a metal compound.

8. An erosion resistant conductive coating structure as claimed in claim 7 wherein at least one functional layer is made of a metal compound.

9. The corrosion protective conductive coating structure of claim 7, wherein the noble metal coating has a thickness of 5nm to 20 nm.

10. A fuel cell plate comprising a metal plate having a surface provided with an anti-corrosion conductive coating structure as claimed in any one of claims 7 to 9.

Technical Field

The invention relates to a conductive coating of a battery metal pole plate, in particular to a preparation method and a structure of an anticorrosive conductive coating and a fuel battery pole plate.

Background

Fuel cells are electrochemical devices that convert the chemical energy of reactants into electrical energy, and because of their cleanliness and high efficiency, they have become a promising energy conversion technology. Among various types of fuel cells, Proton Exchange Membrane Fuel Cells (PEMFCs) have the unique advantages of fast start-up, high conversion efficiency, low operating temperature (about 80 ℃), no pollutant emissions, etc., and are considered to be fuel cells with a wide application prospect from automobiles, buses to backup power sources.

Typical PEMFCs are composed of membrane electrodes and bipolar plates, wherein the bipolar plates are important multifunctional components of the PEMFCs, accounting for 80% of the mass and about 30% of the cost of the PEMFC stack. The bipolar plate plays the roles of current collection and conduction, uniform gas distribution and water heat management in the PEMFC, and the conventional bipolar plate made of graphite materials is gradually replaced by a metal bipolar plate due to the difficulty in processing, high cost, difficulty in batch production and the like. However, in the actual operating environment of the fuel cell, the metal bipolar plate is easy to corrode and passivate, metal ions generated by corrosion can pollute the membrane electrode and obstruct proton transmission, thereby affecting the output power of the cell, and the proton exchange membrane can also explode due to corrosion perforation; meanwhile, a passive film generated on the surface of the metal bipolar plate can increase the contact resistance between the bipolar plate and the diffusion layer, thereby reducing the conductivity.

Therefore, the surface modification of the metal bipolar plate is required, and the development and preparation of the coating which has good bonding force with the base material and excellent corrosion resistance and electrical conductivity are important work for solving the industrial application of the metal bipolar plate. The existing metal bipolar plate coating mainly comprises a carbon-based coating (including a graphite coating, a conductive polymer coating and a diamond-like carbon coating), a metal-based coating (including a noble metal coating, a metal carbon/nitride coating and a metal oxide coating), and the metal bipolar plate coating can be prepared by magnetron sputtering, Chemical Vapor Deposition (CVD), Physical Vapor Deposition (PVD), ion plating, electrodeposition, chemical plating, Atomic Layer Deposition (ALD) and other methods. The noble metal coating has excellent conductivity and better corrosion resistance, and is the preferred material. For example, patent application publication No. CN101098010A discloses a method for preparing gold coating using a solution, which can prepare gold coating, but the gold coating prepared by this method is thick and costly; and the coating of the gold coating on the stainless steel substrate is only realized, the problem of poor bonding force between the substrate and the gold coating is not actually solved, and the gold coating is easy to cause failure in the severe environment of the PEMFC.

Disclosure of Invention

The present invention is directed to overcome the above problems and to provide a method for preparing an anticorrosive conductive coating, which not only can obtain a coating having excellent bonding force, corrosion resistance and conductivity, but also can reduce the amount of noble metal in the coating, thereby contributing to the reduction of manufacturing cost.

The invention also aims to provide a preparation structure of the anticorrosive conductive coating and a fuel cell polar plate.

The purpose of the invention is realized by the following technical scheme:

a preparation method of an anticorrosive conductive coating comprises the following steps:

(1) cleaning a substrate, and placing the substrate in a vacuum chamber;

(2) vacuumizing the vacuum chamber;

(3) heating the vacuum chamber;

(4) sputtering a transition metal target or a metal oxide target for at least two times by using plasma to generate at least two functional coatings on a base material, wherein the functional coatings are transition metal coatings or metal compound coatings;

(5) and sputtering the noble metal target material by using plasma to form the noble metal coating.

In a preferable embodiment of the present invention, in the step (2), after the vacuum pumping, the vacuum degree of the vacuum chamber is not less than 5 × 10^{- 3}Pa。

In a preferable embodiment of the present invention, in the step (3), after the heating, the temperature of the vacuum chamber is 80 to 250 ℃;

in a preferred embodiment of the present invention, in the step (4), the substrate is plasma-cleaned with argon ions for 1 to 30 minutes before sputtering the target. Therefore, the argon ions are used for bombarding the target material to clean the oxide on the surface of the target material, so that the roughness is increased, and the bonding force between the base material and the first functional layer is enhanced to a certain degree. By using bias sputtering, atoms with poor binding force on the surface of the substrate can be knocked off, the film forming quality and the binding force are improved, and the ion cleaning effect is taken into consideration.

Preferably, bias sputtering is started when the operating pressure in the vacuum chamber reaches 0.01 to 1 Pa.

In a preferred embodiment of the present invention, in the step (4), before sputtering the target each time, an auxiliary sputtering gas with a concentration of more than 99% is introduced.

Preferably, the auxiliary sputtering gas is nitrogen or acetylene or methane.

An anticorrosion conductive coating structure comprises a noble metal coating and at least two functional coatings, wherein the functional coatings are positioned between a base material and the noble metal coating;

the functional coating is made of a transition metal or a metal compound.

In a preferred embodiment of the present invention, at least one of the functional layers is made of a metal compound.

In a preferred embodiment of the present invention, the thickness of the noble metal coating is 5nm to 20nm, which can ensure good conductivity and control low production cost.

A fuel cell polar plate comprises a metal polar plate, wherein a corrosion-resistant conductive coating structure is arranged on the surface of the metal polar plate.

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

1. the preparation method of the anticorrosive conductive coating utilizes the transition metal or the metal compound as the functional layer to connect the noble metal and the base material, thereby realizing excellent bonding performance and corrosion resistance between the coating and the base material; the outermost layer of the coating is a noble metal layer, ensuring excellent electrical conductivity and corrosion resistance. The functional layer adopts low-cost transition metal or metal compound to ensure excellent corrosion resistance and binding force, so that the gold coating can be ultrathin or partially covered on the functional layer, the consumption of noble metal is greatly reduced, and the cost is reduced.

2. The pinhole defect caused by the inherent defect of the coating preparation process can be reduced to the maximum extent by a layer-by-layer deposition method, and the depth range of the pinhole defect can be accurately controlled.

Drawings

FIG. 1 is a schematic structural view of an anticorrosive conductive coating according to the present invention; wherein, 1 is a substrate, 2 is a first functional layer, 3 is a second functional layer, 4 is a third functional layer, 5 is a fourth functional layer, and 6 is a noble metal layer.

FIG. 2 is a graph comparing the corrosion current density of bare 316L stainless steel plates with two coatings prepared by the method of preparing the anticorrosive conductive coating according to the present invention, wherein Ag-coated is the corrosion current density curve of the first coating, Au-coated is the corrosion current density curve of the second coating, and SS316L is the corrosion current density of bare 316L stainless steel plates; the test environment is as follows: PH2H₂SO₄+5PPMHF solution, 80 ℃.

FIG. 3 is a graph showing the results of measuring the contact resistance of two kinds of coatings prepared by the method for preparing an anticorrosive conductive coating according to the present invention with a bare 316L stainless steel plate (SS 316L); wherein Ag-coated is a bar graph of the first coating Au-coated is a bar graph of the second coating, and SS316L is a bar graph of a bare 316L stainless steel plate; pre-test refers to the contact resistance before testing, and post-test refers to the contact resistance after testing.

Detailed Description

In order to make those skilled in the art understand the technical solutions of the present invention well, the following description of the present invention is provided with reference to the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

Referring to fig. 1, the fuel cell plate in this embodiment includes a metal plate, and a corrosion-resistant conductive coating structure is disposed on a surface of the metal plate; the coating structure comprises a noble metal coating and at least two functional coatings, wherein the functional coatings are positioned between a base material and the noble metal coating; the functional coating is made of a transition metal or a metal compound. Specifically, the functional coating in this embodiment is provided with four layers; wherein at least one functional layer is made of a metal compound.

The thickness of the noble metal coating is 5nm-20nm, so that good conductivity can be ensured, and low production cost can be controlled. Specifically, the noble metal may be Pt, Pd, Rh, Ru, Au, Ag, or the like.

Specifically, the preparation method of the anti-corrosion conductive coating in this embodiment is as follows:

putting the 316L stainless steel substrate treated by the cleaning process into a vacuum chamber, and vacuumizing to 8 x10^-3After Pa, starting heating; when the temperature of the vacuum chamber reaches 120 ℃, the vacuum degree reaches 8 multiplied by 10 again^-3When Pa is needed, introducing high-purity argon (the purity is 99.99 percent), and carrying out plasma enhanced cleaning on the surface of the target material for 5 minutes; sputtering a high-purity transition metal target (purity 99.99%) by using 100V bias plasma for 20 minutes to form a first functional layer with the thickness of 20 nm; introducing high-purity nitrogen (with the purity of 99.99%), and performing bias plasma co-sputtering for 20 minutes to form a second functional layer with the thickness of 20 nm; introducing high-purity acetylene (the purity is 99.99%), and performing bias plasma co-sputtering for 10 minutes to form a third functional layer with the thickness of 10 nm; closing the high-purity nitrogen, and carrying out bias plasma co-sputtering for 10 minutes to form a fourth functional layer with the thickness of 10 nm; and forming a noble metal layer with the thickness of 5-20nm by adopting a high-frequency pulse magnetron sputtering silver target.

The coatings prepared in this example were tested for corrosion resistance, as shown by the curve Ag-coated in FIG. 2, and electrical conductivity, as shown in FIG. 3. The corrosion current density of the coating made by the embodiment is 1.14x10-8A/cm2, which is much less than that of a bare 316L stainless steel plate; the contact resistance value before the test was 3.25m Ω · cm 2. The contact resistance value after the test is 3.29m omega-cm 2, which is much smaller than that of a bare 316L stainless steel plate, the corrosion resistance and the conductivity are excellent, and the surface of the coating is not changed before and after the test, which shows excellent binding force and stability.

Example 2

The preparation method of the anticorrosive conductive coating in the embodiment comprises the following steps:

putting the 316L stainless steel substrate treated by the cleaning process into a vacuum chamber, vacuumizing to 3x10 < -3 > Pa, and starting heating; when the temperature of the vacuum chamber reaches 200 ℃ and the vacuum degree reaches 3 multiplied by 10 < -3 > Pa again, introducing high-purity argon (with the purity of 99.99 percent) and carrying out plasma enhanced cleaning on the surface of the target material for 5 minutes; sputtering a high-purity transition metal target (purity 99.99%) by using 80V bias plasma for 25 minutes to form a first functional layer with the thickness of 20 nm; introducing high-purity nitrogen (with the purity of 99.99%), and performing bias plasma co-sputtering for 25 minutes to form a second functional layer with the thickness of 20 nm; introducing high-purity acetylene (the purity is 99.99%), and performing bias plasma co-sputtering for 25 minutes to form a third functional layer with the thickness of 20 nm; closing the high-purity nitrogen, and carrying out bias plasma co-sputtering for 25 minutes to form a fourth functional layer with the thickness of 20 nm; and forming a noble metal layer with the thickness of 5-20nm by adopting a high-frequency pulse magnetron sputtering gold target.

The corrosion resistance and conductivity of the coating prepared in this example were measured, wherein the corrosion resistance is shown by the curve Au-coated in FIG. 2 and the conductivity is shown by FIG. 3. The corrosion current density of the coating made by the embodiment is 6.23x10-9A/cm2, which is much less than that of a bare 316L stainless steel plate; the contact resistance value before the test was 3.15m Ω · cm 2. The contact resistance value after the test is 3.11m omega-cm 2, which is much less than that of a bare 316L stainless steel plate, the corrosion resistance and the conductivity are excellent, and the surface of the coating is not changed before and after the test, which shows excellent binding force and stability

The present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents and are included in the scope of the present invention.