CN113097520A

CN113097520A - Stainless steel bipolar plate and preparation method thereof

Info

Publication number: CN113097520A
Application number: CN202110334823.8A
Authority: CN
Inventors: 郑威; 赵俊亮; 张志宽; 孙小卫
Original assignee: Shenzhen Planck Innovation Technology Co ltd
Current assignee: Shenzhen Planck Innovation Technology Co ltd
Priority date: 2021-03-29
Filing date: 2021-03-29
Publication date: 2021-07-09
Anticipated expiration: 2041-03-29
Also published as: CN113097520B

Abstract

The invention relates to a stainless steel bipolar plate and a preparation method thereof, wherein the stainless steel bipolar plate comprises a stainless steel substrate, and a Cr film, a CrN film and a TiCN film which are deposited in sequence; the thickness of the Cr film is 0.4-0.6 μm; the thickness of the CrN film is 0.8-1.1 μm, and the CrN film comprises the following components in atomic percentage: cr 65-75%, N25-35%; the TiCN film is 1.8-2.2 μm thick and comprises the following components in atomic percentage: 45-55% of Ti, 30-40% of N and 10-20% of C. The stainless steel bipolar plate provided by the invention has the advantages that the nano coating structure is adopted, the film layers have good binding force, the corrosion resistance is good, the working power density is obviously improved, the performance of a gold-plated electrode is achieved, and the cost of the electrode is obviously reduced. The power density of the galvanic pile formed by 9 bipolar plates is improved by 20 percent or more compared with that of a TiN pole piece.

Description

Stainless steel bipolar plate and preparation method thereof

Technical Field

The invention relates to the field of fuel cells, in particular to a stainless steel bipolar plate and a preparation method thereof.

Background

The current bottleneck of fuel cells is high cost, and the limitations in use are represented by the compatibility of working temperature, the sensitivity to environmental toxicity and the durability of start-stop cycle. The polymer electrolyte membrane fuel cell is divided into five categories according to the difference of fuel cell electrolytes, and the polymer electrolyte membrane fuel cell can work at low temperature (80 ℃) due to the adoption of the polymer electrolyte membrane electrolyte and has higher power density, so the polymer electrolyte membrane fuel cell is more attractive in application.

The bipolar plate as the important component of the polymer electrolyte membrane fuel cell accounts for over 70 percent of the weight of the electric pile, about 50 percent of the volume, and the cost is about 30 to 50 percent of the cost of the cell. Currently, bipolar plate materials are mainly classified into 3 types, namely graphite bipolar plates, composite bipolar plates and metal bipolar plates.

The graphite bipolar plate is mainly domestic, has light weight, good corrosion resistance and excellent electric and heat conducting performance, but has large brittleness, high price and high flow field processing cost; the composite bipolar plate has high cost, poor conductivity and good corrosion resistance in the domestic research and development stage. For example, CN110204669A discloses a liquid resin for preparing a graphite bipolar plate and a graphite bipolar plate prepared from the liquid resin. The preparation method of the liquid resin for preparing the graphite bipolar plate comprises the following steps: putting aldehyde substances, alkylphenol and phenol into a reaction kettle, stirring uniformly, then putting alkaline catalyst, and heating for reaction; adding alcohol substances, and continuously stirring for reaction at a temperature rising degree; and finally, adding melamine, silicone oil, silicone grease and polyvinyl alcohol substances, stirring and reacting completely, stopping heating, and discharging at room temperature to obtain the resin binder for the adhesive graphite. The adopted liquid resin can be better mixed with graphite powder, the conductivity of the graphite bipolar plate is improved, and the compactness is better.

The metal bipolar plate is mature in foreign industrialization, is in a research and development stage at home, is strong in plasticity, but has the main defect of easy corrosion under the condition of strong acid and high humidity. For example, CN109560305A discloses a metal bipolar plate, comprising: an anode negative film (1) and a cathode negative film (2); a sealing gasket (3) is arranged between the anode bottom plate (1) and the cathode bottom plate (2); one surface of the cathode bottom sheet (2) adjacent to the sealing gasket (3) is provided with a cooling water flow channel plate (4), and the other surface of the cathode bottom sheet (2) is provided with a cathode flow channel plate (5); and an anode runner plate (14) is arranged on the surface of the anode bottom sheet (1) opposite to the sealing gasket (3). The metal bipolar plate is different from the bipolar plate formed by integral stamping in the prior art, the bottom plate and the runner plate are assembled in a split mode, expensive stamping die equipment is not needed, hidden dangers such as material internal stress concentration and workpiece cracking in stamping forming are avoided, production cost is low, the process flow is simple, and the metal bipolar plate has high practical value.

Stainless steel is used as one of metal bipolar plates, has the characteristics of low cost, high strength and easiness in processing, is easy to corrode in an acid damp heat environment, forms a passivation film on the surface, and causes increase of internal resistance of a battery, and causes reduction of power density of the battery due to too low stack working current under a constant voltage condition. For example, CN110699647A discloses a method for modifying a stainless steel bipolar plate of a fuel cell, which comprises the following steps: pretreatment: removing oil stains on the surface of the stainless steel bipolar plate by using an organic reagent, and polishing the surface of the bipolar plate by electropolishing; coating a film for the first time: placing the treated bipolar plate into a vacuum chamber for vacuum pumping until the gas pressure in the vacuum chamber is lower than 1.0 × 10^-3Pa, passing high-purity Ar gas into the vacuum chamber, and coating the bipolar plate by pulse bias arc ion plating, wherein the modified layer adopts a metal base material; coating a film for the second time: and (3) immersing the bipolar plate subjected to the first film plating into the composite plating solution in the chemical plating bath to finally obtain a uniform and compact plated layer without peeling. The invention firstly plates a CrAlN coating on the stainless steel bipolar plate by arc ion plating, thereby improving the bipolar performanceThe outer layer of the plate has oxidation resistance and corrosion resistance, and a nickel coating is plated on the CrAlN coating in a chemical plating mode, so that the nickel coating has good wear resistance, high hardness and certain corrosion resistance.

And the use of titanium as the bipolar plate material has higher cost. Although the titanium oxide film can maintain stable performance in both cathode and anode environments, corrosion hardly occurs. However, in the anode environment, due to the presence of oxygen in the atmosphere, a new titanium oxide film is generated on the titanium surface, although the corrosion resistance of titanium can be enhanced, the titanium oxide film has poor conductivity, the surface contact resistance of the titanium oxide film is increased, the resistance is increased along with the increase of the thickness of the titanium oxide film, and the current is dissipated in the form of heat, so that the power of the pile is reduced.

In order to improve the corrosion resistance and reduce the production cost, the common method at present is to carry out surface treatment on the stainless steel bipolar plate by means of co-infiltration, electroplating and magnetron sputtering, and precious metals such as gold are plated, but the cost is too high to be produced in mass. And also has nitride or carbide coating, such as TiN coating or TiC coating, with reduced cost, and the corrosion current density of the TiN coated bipolar plate is 5 × 10^-7A cm2, poor corrosion resistance, and the contact resistance of a pile consisting of 9 bipolar plates is generally between 7 and 8m omega mm2, the working current is 5.28A under the working voltage of 5.4V, the power density is low, and the problem of poor film bonding force is also caused.

Disclosure of Invention

In view of the problems in the prior art, an object of the present invention is to provide a stainless steel bipolar plate and a method for manufacturing the same, wherein the stainless steel bipolar plate has a nano-coating structure, has good corrosion resistance, and significantly improves working power density, thereby achieving the performance of a gold-plated electrode and significantly reducing the cost of the electrode.

In order to achieve the purpose, the invention adopts the following technical scheme:

in a first aspect, the invention provides a stainless steel bipolar plate, which comprises a stainless steel substrate, and a Cr film, a CrN film and a TiCN film which are deposited in sequence;

the thickness of the Cr film is 0.4-0.6 μm;

the thickness of the CrN film is 0.8-1.1 μm, and the CrN film comprises the following components in atomic percentage: cr 65-75% and N25-35%;

the TiCN film is 1.8-2.2 μm thick and comprises the following components in atomic percentage: 45-55% of Ti, 30-40% of N and 10-20% of C.

The stainless steel bipolar plate provided by the invention has the advantages that the nano coating structure is adopted, the film layers have good binding force, the corrosion resistance is good, the working power density is obviously improved, the performance of a gold-plated electrode is achieved, and the cost of the electrode is obviously reduced. The power density of the galvanic pile formed by 9 bipolar plates is improved by 20 percent or more compared with that of a TiN-plated pole piece.

In the invention, the Cr film, the CrN film and the TiCN film are deposited on the whole surface of the substrate, but not on a single surface.

In the present invention, the thickness of the Cr film is 0.4 to 0.6. mu.m, and may be, for example, 0.4. mu.m, 0.41. mu.m, 0.42. mu.m, 0.43. mu.m, 0.44. mu.m, 0.45. mu.m, 0.46. mu.m, 0.47. mu.m, 0.48. mu.m, 0.49. mu.m, 0.5. mu.m, 0.51. mu.m, 0.52. mu.m, 0.53. mu.m, 0.54. mu.m, 0.55. mu.m, 0.56. mu.m, 0.57. mu.m, 0.58. mu.m, 0.59. mu.m, or 0.6. mu.m, but not limited thereto, and other values not specifically recited in the range are also.

In the present invention, the thickness of the CrN film is 0.8 to 1.1. mu.m, and may be, for example, 0.8. mu.m, 0.81. mu.m, 0.82. mu.m, 0.83. mu.m, 0.84. mu.m, 0.85. mu.m, 0.86. mu.m, 0.87. mu.m, 0.88. mu.m, 0.89. mu.m, 0.9. mu.m, 0.91. mu.m, 0.92. mu.m, 0.93. mu.m, 0.94. mu.m, 0.95. mu.m, 0.96. mu.m, 0.97. mu.m, 0.98. mu.m, 0.99. mu.m, 1. mu.m, 1.01. mu.m, 1.02. mu.m, 1.03. mu.m, 1.04. mu.m, 1.05. mu.m, 1.06. mu.m, 1.07. mu.m, 1.08. mu.m, 1.m, or the like, but the values in the.

In the present invention, the Cr content in the CrN film is 65 to 75% by atomic percentage, and may be, for example, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, or 75%, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

In the present invention, the content of N in the CrN film is 25 to 35% by atomic percentage, and may be, for example, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, or the like, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

In the present invention, the thickness of the TiCN film is 1.8 to 2.2. mu.m, and examples thereof include, but are not limited to, 1.8. mu.m, 1.81. mu.m, 1.82. mu.m, 1.83. mu.m, 1.84. mu.m, 1.85. mu.m, 1.86. mu.m, 1.87. mu.m, 1.88. mu.m, 1.89. mu.m, 1.9. mu.m, 1.91. mu.m, 1.92. mu.m, 1.93. mu.m, 1.94. mu.m, 1.95. mu.m, 1.96. mu.m, 1.97. mu.m, 1.98. mu.m, 1.99. mu.m, 2. mu.01. mu.m, 2.02. mu.03. mu.m, 2.04. mu.m, 2.05. mu.m, 2.06. mu.m, 2.07. mu.08. mu.m, 2.09. mu.m, 2.1. mu.11. mu.m, 2.12. mu.13. mu.m, 2.19. mu.19. mu.m, 2.19. mu.m, and the like, and the other values are not specifically recited in the same ranges.

In the present invention, the content of Ti in the TiCN film is 45 to 55% by atomic percentage, and may be, for example, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or 55%, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

In the present invention, the content of N in the TiCN film is 30 to 40% by atomic percentage, and may be, for example, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

In the present invention, the content of C in the TiCN film is 10 to 20% by atomic percentage, and may be, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.

As a preferable embodiment of the present invention, the total thickness of the Cr film, the CrN film and the TiCN film is 3 to 3.4. mu.m, and may be, for example, 3 μm, 3.01. mu.m, 3.02. mu.m, 3.03. mu.m, 3.04. mu.m, 3.05. mu.m, 3.06. mu.m, 3.07. mu.m, 3.08. mu.m, 3.09. mu.m, 3.1. mu.m, 3.11. mu.m, 3.12. mu.m, 3.13. mu.m, 3.14. mu.m, 3.15. mu.m, 3.16. mu.m, 3.17. mu.m, 3.18. mu.m, 3.19. mu.m, 3.2. mu.m, 3.3. mu.4. mu.m, etc., but not limited thereto, and other values not recited in the range can be applied.

In the invention, the total thickness of the Cr film, the CrN film and the TiCN film refers to the thickness of the Cr film, the CrN film and the TiCN film along the direction vertical to the horizontal plane by taking the stainless steel bipolar plate as the horizontal plane, namely the thickness of one side of the stainless steel bipolar plate, but not the sum of the thicknesses of two sides.

In a second aspect, the present invention provides a method for preparing a stainless steel bipolar plate electrode according to the first aspect, the method comprising the steps of:

(1) sequentially carrying out first cleaning, polishing, second cleaning and drying on a stainless steel bipolar plate sample to obtain a stainless steel bipolar plate substrate;

(2) and (2) carrying out plasma treatment and film coating on the stainless steel bipolar plate substrate obtained in the step (1) to obtain the stainless steel bipolar plate.

As a preferable technical scheme of the invention, the first cleaning in the step (1) is to sequentially use a wax removal cleaning agent and an oil removal cleaning agent for cleaning.

As a preferable technical scheme of the invention, the polishing mode in the step (1) comprises electrolytic polishing.

As a preferable technical solution of the present invention, the second cleaning mode in the step (1) is ultrasonic cleaning.

Preferably, the cleaning agent in the second cleaning in the step (1) comprises ethanol.

In the invention, the cleaning and polishing are conventional operations carried out in the field for realizing a good film coating effect, and the specific operation conditions can refer to the prior art for operation, such as that the first cleaning is carried out by firstly adopting a wax removal cleaning agent according to the proportion of cleaning agent to pure water being 1:1, putting the cleaning agent into an ultrasonic cleaning tank, setting the temperature to be 60-80 ℃, and carrying out ultrasonic treatment for about 10-20min, then replacing the oil cleaning agent, and carrying out the cleaning and polishing according to the same proportion and the same ultrasonic parameter setting; polishing by adopting NaCl aqueous solution electrolyte with the concentration of 14-18%, heating to 60-75 ℃, fixing stainless steel on an anode by using a proper hanger, keeping a workpiece opposite to a cathode, adjusting voltage and current, taking out the workpiece after polishing for 3-5 minutes, and finishing an electrolytic polishing process; the second cleaning is washing by pure water, ultrasonic cleaning by adding ethanol, setting the temperature of an ultrasonic groove at 50-60 ℃, and ultrasonic time at about 5-7 min; the drying is drying in a drying oven at 90-100 deg.C for 20-30 min.

In the invention, the wax removal cleaning agent and the oil removal cleaning agent can be the conventional cleaning agent, and the wax and the oil on the surface of the substrate can be cleaned completely.

In a preferred embodiment of the present invention, the plasma treatment in step (1) is performed under a protective atmosphere.

In the present invention, the protective atmosphere in the plasma treatment may be a gas that does not react with the substrate, such as helium or neon. In the plasma treatment, the treated stainless steel bipolar plate is placed on a multifunctional coating cavity rotating frame support, and the rotating frame supports revolution and rotation, so that the surface of a sample can be ensured to be covered by a film layer in multiple dimensions; starting the vacuum pump to pump air until the air pressure is lower than 1 × 10^-3And after Pa, setting the heating temperature to 150-160 ℃, baking the water vapor in the cavity for half an hour to dry the cavity, and then introducing working gas argon to start treatment.

Preferably, the pressure of the protective atmosphere is 10 to 30Pa, and may be, for example, 10Pa, 12Pa, 14Pa, 16Pa, 18Pa, 20Pa, 22Pa, 24Pa, 26Pa, 28Pa, or 30Pa, but is not limited to the recited values, and other values not recited in the range are also applicable.

Preferably, the plasma treatment time in step (1) is 30-40min, such as 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min or 40min, but not limited to the recited values, and other values not recited in the range are also applicable.

As a preferable technical scheme of the invention, the plating film in the step (2) comprises a Cr plating film, a CrN plating film and a TiCN plating film which are sequentially carried out.

In a preferred embodiment of the present invention, the Cr plating is performed under an inert atmosphere having a pressure of 0.4 to 0.6Pa, and may be, for example, 0.4Pa, 0.42Pa, 0.44Pa, 0.46Pa, 0.48Pa, 0.5Pa, 0.52Pa, 0.54Pa, 0.56Pa, 0.58Pa, or 0.6Pa, but not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

In the invention, the Cr is plated by adopting a magnetic control plane target or a multi-arc target. After ion cleaning is finished, introducing argon, and controlling the air pressure to be between 0.4 and 0.6Pa by adjusting the opening of the flashboard valve and the flow of the argon; then, a substrate table is biased by 200V, a rotating frame is set to be 6-10r/min, multi-arc metal Cr target current is set to be 100A, gas is discharged through an arc ignition needle to generate electric arcs, the temperature of the electric arcs on the surface of the target materials is too high, the electric arcs are locally melted and sputtered onto the substrate in a gasification mode, an excitation power supply is set to be 50-70Hz, the duty ratio is 50-80%, the electric arcs are pressed upwards by 5V and downwards by-5V, the electric arcs are guaranteed to move more uniformly and stably, and further a pure Cr interface transition layer is obtained.

Preferably, the flow rate of the inert gas in the Cr-plated film is 250-350sccm, such as 250sccm, 260sccm, 270sccm, 280sccm, 290sccm, 300sccm, 310sccm, 320sccm, 330sccm, 340sccm, or 350sccm, but not limited to the above-mentioned values, and other values not listed in the range are also applicable.

Preferably, the temperature of the Cr-plated film is 150-200 ℃, for example, 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃ or 200 ℃, etc., but not limited to the recited values, and other values not recited in the range are also applicable.

Preferably, the Cr plating time is 10 to 15min, for example, 10min, 10.5min, 11min, 11.5min, 12min, 12.5min, 13min, 13.5min, 14min, 14.5min, or 15min, but is not limited to the values listed, and other values not listed in this range are also applicable.

Preferably, the CrN plating film is performed under a mixed atmosphere of an inert gas and nitrogen.

In the invention, the CrN coating is plated by adopting a multi-arc metal Cr target, the current is controlled at 100A, an excitation power supply is set at 50-70Hz, the duty ratio is 50-80%, the voltage is increased by 5V and decreased by-5V, the temperature in a cavity is controlled at 150-200 ℃, and the arc ion plating of the CrN coating is completed.

Preferably, the flow rate of the inert gas in the CrN plating film is 150sccm, 160sccm, 170sccm, 180sccm, 190sccm, 200sccm, 210sccm, 220sccm, 230sccm, 240sccm or 250sccm, for example, but not limited to the above-mentioned values, and other values not listed in the range are also applicable.

Preferably, the flow rate of nitrogen in the CrN plating film is 130-170sccm, such as 130sccm, 140sccm, 150sccm, 160sccm, or 170sccm, but not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the CrN plating time is 30-45min, such as 30min, 31min, 32min, 33min, 34min, 35min, 36min, 37min, 38min, 39min, 40min, 41min, 42min, 43min, 44min or 45min, but not limited to the enumerated values, and other unrecited values in this range are also applicable.

Preferably, the TiCN plating film is performed under a mixed atmosphere of an inert gas, acetylene, and nitrogen.

In the invention, the TiCN coating is plated by adopting a multi-arc Ti target, the current is controlled at 100A, the exciting power supply is set at 60-80Hz, the duty ratio is 50-60%, the voltage is increased by 5V and decreased by-5V, the temperature in the cavity is controlled at 200 ℃ for completing the arc ion plating of the TiCN coating.

Preferably, the flow rate of the inert gas in the TiCN plating film is 150-250sccm, such as 150sccm, 160sccm, 170sccm, 180sccm, 190sccm, 200sccm, 210sccm, 220sccm, 230sccm, 240sccm or 250sccm, but is not limited to the above-mentioned values, and other values not listed in the range are also applicable.

Preferably, the flow rate of acetylene in the TiCN plating film is 25-35sccm, such as 25sccm, 26sccm, 27sccm, 28sccm, 29sccm, 30sccm, 31sccm, 32sccm, 33sccm, 34sccm, or 35sccm, but is not limited to the values listed, and other values not listed in this range are also applicable.

Preferably, the flow rate of nitrogen in the TiCN plating film is 130-170sccm, such as 130sccm, 140sccm, 150sccm, 160sccm, or 170sccm, but not limited to the values listed, and other values not listed in the range are also applicable.

Preferably, the time for coating the TiCN film is 60-70min, such as 60min, 62min, 64min, 66min, 68min or 70min, but not limited to the values listed, and other values not listed in the range are also applicable.

As a preferred technical scheme of the invention, the preparation method comprises the following steps:

(2) carrying out plasma treatment and film coating on the stainless steel bipolar plate substrate obtained in the step (1) to obtain the stainless steel bipolar plate;

the plasma treatment is carried out in a protective atmosphere, the pressure of the protective atmosphere is 10-30Pa, and the plasma treatment time is 30-40 min;

the film plating comprises a Cr film, a CrN film and a TiCN film which are sequentially plated;

the Cr plating film is carried out in an inert atmosphere with the air pressure of 0.4-0.6 Pa; the flow rate of the inert gas in the Cr-plated film is 250-350 sccm; the temperature of the Cr coating is 150-200 ℃; the time for plating the Cr film is 10-15 min;

the CrN plating film is carried out in the mixed atmosphere of inert gas and nitrogen, the flow rate of the inert gas in the CrN plating film is 150-250sccm, the flow rate of the nitrogen in the CrN plating film is 130-170sccm, and the CrN plating time is 30-45 min;

the TiCN film plating is carried out in the mixed atmosphere of inert gas, acetylene and nitrogen, the flow rate of the inert gas in the TiCN film plating is 150-250sccm, the flow rate of the acetylene in the TiCN film plating is 25-35sccm, the flow rate of the nitrogen in the TiCN film plating is 130-170sccm, and the TiCN film plating time is 60-70 min.

The TiCN film is adopted in the invention because the TiN crystal structure is a face-centered cubic NaCl structure with Ti atoms occupying the apex angle of the face-centered cubic, and generally has Ti-N covalent bonds and Ti-Ti metal bonds, the film hardness is relatively low, and the friction coefficient is higher. The TiCN composite film has both a nanocrystalline structure (capable of increasing hardness) and an amorphous carbon structure (lubricating phase and reducing friction coefficient), is columnar, and is formed into a substitutional solid solution by replacing N atoms in TiN lattices with doped C atoms along with the increase of C content in the TiCN film.

Meanwhile, the structure of C in the TiCN structure comprises sp2 (graphite-like, resistance is reduced) and sp3 (diamond-like, hardness is high) structures, so that the hardness of the film is improved, and the friction coefficient is reduced; however, the content of C cannot be too high, which can cause too much graphite phase, the toughness of the film layer is deteriorated, and the binding force is reduced to cause the film layer to fall off. Cr and CrN are used as transition layers and are arranged between a stainless steel substrate and a target film layer TiCN to play roles in buffering internal stress of an interface and improving adhesion, Cr is generally used as a bottom layer, and CrN has excellent corrosion resistance. The crystal lattices of Cr, CrN and TiCN are mismatched, columnar crystals are inhibited, a large number of interfaces exist among multiple layers of films, crystal grains are refined, the formation and movement of defects are inhibited, the thermal expansion coefficient and the lattice constant of the material are close, the compactness is improved, the corrosion resistance is improved, and meanwhile, the bonding force of the film layer is also improved.

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

by adopting the arrangement of multilayer coating, the bonding force between the coating and the stainless steel substrate is improved, the corrosion resistance is improved, and the corrosion current density is from 5 multiplied by 10^-7A cm2 to 1X 10^-7A cm2, improves the working power density, and the working current of Cr/CrN/TiCN film system is increased from 5.28A to 6.6A compared with TiN under the same working voltage, and the contact resistance of Cr/CrN/TiCN film system is 5-5.3m omega mm 2.

Drawings

Fig. 1 is a schematic view of a stainless steel bipolar plate provided in example 1 of the present invention.

In the figure: 1-stainless steel substrate, 2-Cr film, 3-CrN film and 4-TiCN film.

The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

Detailed Description

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:

example 1

This example provides a stainless steel bipolar plate and a method for manufacturing the same, where the stainless steel bipolar plate includes a stainless steel substrate 1, and a Cr film 2, a CrN film 3, and a TiCN film 4 deposited in sequence, as shown in fig. 1;

the thickness of the Cr film 2 is 0.5 μm;

the thickness of the CrN film 3 is 0.8 μm, and the CrN film comprises the following components in atomic percentage: 70% of Cr and 30% of N;

the TiCN film 4 is 1.8 μm thick and comprises the following components in atomic percentage: 50% of Ti, 35% of N and 15% of C.

The preparation method comprises the following steps:

the first cleaning is to sequentially adopt a wax removal cleaning agent and an oil removal cleaning agent for cleaning, the polishing mode is electrolytic polishing, the second cleaning mode is ultrasonic cleaning, and the cleaning agent in the second cleaning comprises ethanol;

the plasma treatment is carried out under a protective atmosphere after the cavity is vacuumized to 0.001Pa and baked for 40min at 150 ℃, the pressure of the protective atmosphere is 20Pa, and the plasma treatment time is 35 min;

the Cr plating film is carried out in an inert atmosphere with the air pressure of 0.5 Pa; the flow rate of the inert gas in the Cr-plated film is 300 sccm; the temperature of the Cr coating is 150 ℃; the Cr film plating time is 12 min;

adopting a multi-arc target to plate Cr, introducing argon after ion cleaning is finished, and adjusting the opening of a flashboard valve and the flow of the argon to control the air pressure; then, a substrate table is biased by 200V, a rotating frame is set to be 8r/min, multi-arc metal Cr target current is set to be 100A, gas is discharged to generate electric arcs through an arc ignition needle, the electric arcs on the surface of the target are over-high in temperature and are locally hot-melted and gasified and sputtered onto the substrate, an excitation power supply is set to be 60Hz and 70% of duty ratio, 5V is pressed upwards and 5V is pressed downwards, and a pure Cr interface transition layer is obtained.

The CrN plating is carried out in the mixed atmosphere of inert gas and nitrogen, the flow of the inert gas in the CrN plating is 200sccm, the flow of the nitrogen in the CrN plating is 150sccm, and the CrN plating time is 37 min;

the CrN coating is plated by adopting a multi-arc metal Cr target, the current is controlled at 100A, an excitation power supply is set at 60Hz, the duty ratio is 60%, the voltage is increased by 5V and decreased by-5V, the temperature in a cavity is controlled at 150 ℃, and the arc ion plating of the CrN coating is completed.

The TiCN coating is carried out in the mixed atmosphere of inert gas, acetylene and nitrogen, the flow of the inert gas in the TiCN coating is 200sccm, the flow of the acetylene in the TiCN coating is 30sccm, the flow of the nitrogen in the TiCN coating is 150sccm, and the TiCN coating time is 65 min.

The TiCN coating is plated by adopting a multi-arc Ti target, the current is controlled at 100A, an excitation power supply is set at 60Hz, the duty ratio is 50%, the voltage is increased by 5V and is decreased by-5V, the temperature in the cavity is controlled at 150 ℃, and the arc ion plating of the TiCN coating is completed.

The properties of the resulting stainless steel bipolar electrode plate are detailed in table 1.

Example 2

The embodiment provides a stainless steel bipolar plate and a preparation method thereof, wherein the stainless steel bipolar plate comprises a stainless steel substrate, and a Cr film, a CrN film and a TiCN film which are deposited in sequence;

the thickness of the Cr film is 0.4 mu m;

the thickness of the CrN film is 1.1 mu m, and the CrN film comprises the following components in atomic percentage: cr 65% and N35%;

the TiCN film is 1.8 μm thick and comprises the following components in atomic percentage: 55% of Ti, 30% of N and 15% of C.

The preparation method comprises the following steps:

the first cleaning is to sequentially adopt a wax removal cleaning agent and an oil removal cleaning agent for cleaning, the polishing mode comprises electrolytic polishing, the second cleaning mode is ultrasonic cleaning, and the cleaning agent in the second cleaning comprises ethanol;

the plasma treatment is carried out under a protective atmosphere after the cavity is vacuumized to 0.001Pa and baked for 40min at 150 ℃, the air pressure of the protective atmosphere is 10Pa, and the plasma treatment time is 40 min;

the Cr plating film is carried out in an inert atmosphere with the air pressure of 0.4 Pa; the flow rate of the inert gas in the Cr-plated film is 250 sccm; the temperature of the Cr coating is 150 ℃; the Cr film plating time is 10 min;

The CrN plating is carried out in the mixed atmosphere of inert gas and nitrogen, the flow of the inert gas in the CrN plating is 250sccm, the flow of the nitrogen in the CrN plating is 130sccm, and the CrN plating time is 45 min;

The TiCN coating is carried out in the mixed atmosphere of inert gas, acetylene and nitrogen, the flow of the inert gas in the TiCN coating is 250sccm, the flow of the acetylene in the TiCN coating is 35sccm, the flow of the nitrogen in the TiCN coating is 130ccm, and the TiCN coating time is 60 min.

Example 3

the thickness of the Cr film is 0.4 mu m;

the thickness of the CrN film is 0.8 μm, and the CrN film comprises the following components in atomic percentage: 75% of Cr and 25% of N;

the TiCN film is 2.2 mu m thick and comprises the following components in atomic percentage: 45% of Ti, 35% of N and 120% of C.

The preparation method comprises the following steps:

the plasma treatment is carried out under a protective atmosphere after the cavity is vacuumized to 0.001Pa and baked for 40min at 150 ℃, the pressure of the protective atmosphere is 30Pa, and the plasma treatment time is 30 min;

the Cr plating film is carried out in an inert atmosphere with the air pressure of 0.6 Pa; the flow rate of the inert gas in the Cr-plated film is 350 sccm; the temperature of the Cr coating is 200 ℃; the Cr film plating time is 15 min;

The CrN plating is carried out in the mixed atmosphere of inert gas and nitrogen, the flow of the inert gas in the CrN plating is 150sccm, the flow of the nitrogen in the CrN plating is 170sccm, and the CrN plating time is 30 min;

The TiCN coating is carried out in the mixed atmosphere of inert gas, acetylene and nitrogen, the flow of the inert gas in the TiCN coating is 150sccm, the flow of the acetylene in the TiCN coating is 25sccm, the flow of the nitrogen in the TiCN coating is 170sccm, and the TiCN coating time is 70 min.

Comparative example 1

The only difference from example 1 is that the thickness of the Cr film was 1 μm, and the properties of the resulting stainless steel bipolar electrode plate are specified in Table 1. Cr itself has general conductivity, and too thick primer layer results in increased contact resistance and reduced working current.

Comparative example 2

The difference from example 1 is only that the thickness of the CrN film is 2 μm, and the properties of the resulting stainless steel bipolar electrode plate are detailed in Table 1. Too thick CrN film results in increased contact resistance and reduced operating current.

Comparative example 3

The difference from example 1 is only that the TiCN film has a thickness of 3.5 μm, and the properties of the resulting stainless steel bipolar electrode plate are specified in Table 1. The TiCN film is too thick, so that the contact resistance is reduced, but the internal stress is increased, the bonding force of the film layer is reduced, and the deformation resistance and the anti-stripping resistance of the film layer are obviously reduced. The film bonding force decreases with the increase of the film thickness.

Comparative example 4

The difference from the example 1 is only that a Cr film of 5 μm is further coated on the TiCN film, and the properties of the obtained stainless steel bipolar electrode plate are detailed in Table 1. Cr has general conductivity, and a layer of Cr is plated on TiCN, so that the contact resistance is increased, and the working current is reduced.

Comparative example 5

The difference from example 1 is only that the CrN film was changed to a Ti film of an equal thickness, and the properties of the resulting stainless steel bipolar electrode plate are detailed in table 1. The Ti film has poor self-corrosion resistance and is easy to be oxidized into TiO₂Resulting in an increase in contact resistance.

Comparative example 6

The only difference from example 1 was that the CrN film was not provided, and the properties of the resulting stainless steel bipolar electrode plate were specified in table 1. The absence of the CrN film results in a decrease in the interface, an increase in defects, and a decrease in the corrosion resistance.

TABLE 1

As can be seen from the results of the above examples and comparative examples, the present invention, by employing a specific multi-layered coating, improves the adhesion between the coating and the stainless steel substrate, improves the corrosion resistance, and increases the corrosion current density from 5 × 10^-7A·cm²Down to 1X 10^-7A·cm²The working power density is improved, the working current of the Cr/CrN/TiCN film system is improved to 6.6A from 5.28A under the same working voltage compared with TiN by the galvanic pile consisting of 9 bipolar plates, and the contact resistance of the Cr/CrN/TiCN film system is 5-5.3m omega mm²。

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.

Claims

1. A stainless steel bipolar plate is characterized by comprising a stainless steel substrate, and a Cr film, a CrN film and a TiCN film which are deposited in sequence;

the thickness of the Cr film is 0.4-0.6 μm;

the thickness of the CrN film is 0.8-1.1 μm, and the CrN film comprises the following components in atomic percentage: cr 65-75%, N25-35%;

2. The stainless steel bipolar plate of claim 1, wherein the Cr film, CrN film, and TiCN film have a total thickness of 3 to 3.4 μm.

3. The method of manufacturing a stainless steel bipolar plate according to claim 1 or 2, comprising the steps of:

4. The preparation method according to claim 3, wherein the first cleaning in the step (1) is sequentially performed by using a wax removal cleaning agent and an oil removal cleaning agent.

5. The method according to claim 3 or 4, wherein the polishing means of step (1) comprises electropolishing.

6. The production method according to any one of claims 3 to 5, wherein the second cleaning in step (1) is ultrasonic cleaning;

7. The production method according to any one of claims 3 to 6, wherein the plasma treatment of step (2) is performed under a protective atmosphere;

preferably, the pressure of the protective atmosphere is 10-30 Pa;

preferably, the plasma treatment time of the step (2) is 30-40 min.

8. The production method according to any one of claims 3 to 7, wherein the plating film of the step (2) comprises a Cr plating film, a CrN plating film and a TiCN plating film which are sequentially performed.

9. The method according to claim 8, wherein the Cr plating film is performed in an inert atmosphere at a pressure of 0.4 to 0.6 Pa;

preferably, the flow rate of the inert gas in the Cr-plated film is 250-350 sccm;

preferably, the temperature of the Cr coating is 150-200 ℃;

preferably, the time for plating the Cr film is 10-15 min;

preferably, the CrN plating film is carried out in a mixed atmosphere of inert gas and nitrogen;

preferably, the flow rate of the inert gas in the CrN plating film is 150-250 sccm;

preferably, the flow rate of nitrogen in the CrN plating film is 130-170 sccm;

preferably, the time for plating CrN is 30-45 min;

preferably, the TiCN plating film is performed under a mixed atmosphere of an inert gas, acetylene, and nitrogen;

preferably, the flow rate of the inert gas in the TiCN plating film is 150-250 sccm;

preferably, the flow rate of acetylene in the TiCN-plated film is 25-35 sccm;

preferably, the flow rate of nitrogen in the TiCN-plated film is 130-170 sccm;

preferably, the time for plating the TiCN film is 60-70 min.

10. The method of any one of claims 3 to 9, comprising the steps of: