CN112111716B

CN112111716B - Preparation process of ultralow-resistance corrosion-resistant coating for metal bipolar plate of hydrogen fuel cell

Info

Publication number: CN112111716B
Application number: CN202010819189.2A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Kunshan Hengding New Material Co ltd
Current assignee: Kunshan Hengding New Material Co ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2023-02-28
Anticipated expiration: 2040-08-14
Also published as: CN112111716A

Abstract

The invention provides a preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell, which comprises the following steps of: cleaning the metal bipolar plate, and then baking the metal bipolar plate in an oven; putting the baked metal bipolar plate into a vacuum furnace, and heating and drying in vacuum; introducing argon into the vacuum furnace to ensure that the vacuum degree in the vacuum furnace is 0.5-2.5Pa, and carrying out ion cleaning on the metal bipolar plate for 30-60min by adopting a C target as a radio frequency ion source target source; closing the argon, workpiece bias voltage, ion source and target source, and vacuumizing the vacuum furnace to the vacuum degree of (1.0-8.0) × 10 ^‑3 Pa; and introducing argon into the vacuum furnace, and sequentially plating a Ti base layer, a TiN transition layer and an amorphous carbon film layer on the metal bipolar plate by adopting a plasma enhanced vacuum plane magnetron sputtering method. The preparation process of the invention deposits the corrosion-resistant layer and the conductive layer on the metal bipolar plate in sequence, reduces the surface contact resistance and improves the corrosion resistance.

Description

Preparation process of ultralow-resistance corrosion-resistant coating for metal bipolar plate of hydrogen fuel cell

Technical Field

The invention relates to the technical field of metal bipolar plate coatings, in particular to a preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell.

Background

The proton exchange membrane fuel cell is a new energy cell which directly converts hydrogen energy into electric energy. The novel energy-saving engine has the advantages of high efficiency, environmental protection, high specific energy and specific power, quick start and the like, and has good application prospect. The bipolar plates have the main functions of conducting electrons, distributing chemical fuel, separating individual cells, supporting membrane electrodes, and facilitating water management within the cells, among other functions, in a proton exchange membrane fuel cell. 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 bipolar plate with excellent performances such as ultra-low resistance, high thermal conductivity, high mechanical strength, low stamping cost, low gas permeability and the like is expected to replace the graphite bipolar plate to become a main material. However, the metal bipolar plate is severely corroded in the working environment of the fuel cell, various metal ions in the metal bipolar plate are separated out, the proton exchange membrane is polluted, and the catalyst is degraded, so that the service life of the fuel cell is reduced, and a passivation film is easily formed on the metal surface in an acid environment to increase the contact resistance of the metal bipolar plate and the gas diffusion layer, so that the output power of the cell is reduced.

At present, a protective coating is deposited on the surface of the metal bipolar plate, which is an effective means for improving the surface conductivity and corrosion resistance of the metal bipolar plate. Commonly used protective coatings are noble metal coatings, metal nitride or carbide coatings, conductive polymer coatings, metal boride coatings, and the like.

In the existing coating treatment mode for the surface of the metal bipolar plate: noble metal coatings (Au, ag, pt) are expensive; the pure metal coating has insufficient corrosion resistance and is easy to passivate, so that the surface contact resistance is increased; the metal nitride, oxide and carbide coatings have poor conductivity; moreover, the surface of the coating generally has the defects of pinholes and the like, and corrosive media easily permeate the pinholes to reach the inside of the coating and even a metal substrate, thereby restricting the application effect of the metal bipolar plate.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell, wherein the corrosion-resistant coating and a conductive layer are sequentially deposited on the metal bipolar plate, so that the surface contact resistance of the metal bipolar plate is reduced, and the corrosion resistance of the metal bipolar plate is improved.

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

a preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell comprises the following steps:

step 01, cleaning a metal bipolar plate, and then baking the metal bipolar plate in an oven, wherein the metal bipolar plate is 316L stainless steel or a titanium-based plate;

step 02, placing the baked metal bipolar plate into a vacuum furnace, and controlling the background vacuum degree in the vacuum furnace to be (1.0-8.0) × 10 ^-3 Pa, and heating to dry the metal bipolar plate;

step 03, introducing argon gas with the flow of 200-600sccm into the vacuum furnace to ensure that the vacuum degree in the vacuum furnace is 0.5-2.5Pa, adopting a C target as a radio frequency ion source target source, ensuring that the ion source power is 500-1000W, the voltage is 800-1300V, the target current is 0.2-0.5A or the target voltage is 200-600V, the workpiece bias voltage is-300-600V, the duty ratio is 30-80%, the workpiece rotating frame frequency is 3-15 r/min, and performing ion cleaning on the metal bipolar plate for 30-60min;

step 04, closing the argon gas, the workpiece bias voltage, the ion source and the target source, and vacuumizing the vacuum furnace to the vacuum degree of (1.0-8.0) × 10 ^-3 Pa；

And step 05, introducing argon into the vacuum furnace, and sequentially plating a Ti base layer, a TiN transition layer and an amorphous carbon film layer on the metal bipolar plate by adopting a plasma-enhanced vacuum plane magnetron sputtering method.

Further, in the step 01, the metal bipolar plate is cleaned by ultrasonic waves, and is baked in an oven after sequentially passing through an ultrasonic oil removing groove, a spraying groove, an ultrasonic pure water groove and a pure water slow-pulling groove, wherein the baking temperature is 120-150 ℃ and the baking time is 30-60min.

Further, in the step 01, the metal bipolar plate is cleaned by steam, the workpiece enters a steam furnace, the pressure of a steam outlet is 0.5-1.2Mpa, the temperature in the steam furnace is 90-150 ℃, the cleaning time is 20-40min, the workpiece is taken out of the steam furnace, enters a pure water slow-drawing groove and finally enters an oven for baking, the baking temperature is 120-150 ℃, and the baking time is 20-40min.

Further, in step 02, the drying temperature of the metal bipolar plate is 100-300 ℃, and the time is 30-60min.

Further, in step 05, the number of the Ti-based layers is 2-5, the single-layer time is 2-5min, the argon gas is introduced at a flow rate of 200-600sccm, the target current is 20-40A, the target voltage is 300-600V, the workpiece bias voltage is-30 to-300V, the duty ratio is 30-80%, the workpiece turret frequency is 3-15 r/min, and the coating temperature is 100-300 ℃.

Further, in the step 05, the number of TiN transition layer layers is 2-5, the single-layer time is 2-10min, the argon gas introduction flow is 20-120sccm, the target current is 20-40A, the target voltage is 300-600V, the workpiece bias voltage is-30 to-100V, the duty ratio is 30-80%, the workpiece rotating frame frequency is 3-15 r/min, and the coating temperature is 100-300 ℃.

Further, in step 05, the number of the amorphous carbon film layers is 4-10, the single-layer time is 20-60min, a radio frequency ion source is used as a sputtering power supply of a C target, the ion source power is 800-1500W, the corresponding C target voltage is 800-1500V, the workpiece rotating frame frequency is 6-15 r/min, and the coating temperature is 100-300 ℃.

Further, in step 05, a high-power and high-frequency power supply is adopted as a sputtering power supply for the Ti-based layer, the frequency is 40-120KHz, and the power is 40-60KW.

Compared with the prior art, the invention has the beneficial technical effects that: the invention relates to a preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell, which comprises the steps of sputtering a pure metal Ti base layer by using a high-power and high-frequency pulse power supply, forming a compact corrosion-resistant nano Ti layer on the surface of the metal bipolar plate, and optimizing the adhesion problem between an amorphous carbon film and the nano Ti base layer by using a TiN transition layer;

the outermost layer adopts a radio frequency ion source to deposit an amorphous carbon film layer, and due to the excellent chemical inertia of carbon elements and a special mechanism of amorphous carbon, the compact amorphous carbon film coating deposited on the metal bipolar plate by the special radio frequency ion source has high conductivity and excellent corrosion resistance, so that the working efficiency and the service life of the proton exchange membrane fuel cell are improved; in addition, the preparation process has the advantages of few types of raw materials and air sources, short processing time, easy production control, high reliability of mass production, low cost and high yield.

Drawings

Fig. 1 is a schematic cross-sectional view of a metal bipolar plate processed according to an embodiment of the present invention.

In the figure: 1-metal bipolar plate, 2-Ti base layer, 3-TiN transition layer and 4-amorphous carbon film layer.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention. It should be apparent that the described embodiments are only some of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention, are within the scope of the invention.

The technical scheme of the invention is further explained in detail by combining the drawings in the specification.

Example 1:

and step 01, carrying out ultrasonic cleaning on the metal bipolar plate 1, sequentially passing through an ultrasonic oil removing groove, a spraying groove, an ultrasonic pure water groove and a pure water slow-pulling groove, then baking in an oven, and baking for 60min at 130 ℃.

Step 02, placing the baked metal bipolar plate 1 into a vacuum furnace, and controlling the background vacuum degree in the vacuum furnace to be 4.3 x 10 ^-3 Drying the metal bipolar plate 1 at 200 ℃ for 60min under Pa;

step 03, introducing argon gas with the flow of 500sccm into the vacuum furnace to enable the vacuum degree in the vacuum furnace to be 2.0Pa, setting the power of the ion source to be 1000W, the voltage to be 1200V, the target current to be 0.3A, the target voltage to be 400V, the bias voltage of a workpiece to be 400V, the duty ratio to be 50 percent and the frequency of the workpiece rotating frame to be 6 revolutions per minute, and cleaning the metal bipolar plate 1 for 60 minutes by ions;

step 04, closing argon, workpiece bias voltage, an ion source and a target source, and vacuumizing until the vacuum degree in the vacuum furnace is 6.0 x 10 ^- ³ Pa；

Step 05, introducing argon gas of 400sccm, adopting a high-power medium-frequency power supply as a sputtering power supply of the Ti target, wherein the target current is 35A, the target voltage is 420V, the workpiece bias voltage is-100V, the duty ratio is 30%, the workpiece rotating frequency is 6 r/min, and the coating temperature is 150 ℃; the number of the Ti base layer 2 is 4, and the single-layer time is 5min;

introducing nitrogen gas of 60sccm, wherein the target current is 35A, the target voltage is 400V, the workpiece bias voltage is-30V, the duty ratio is 30%, the workpiece rotating frame frequency is 6 r/min, and the coating temperature is 150 ℃; the number of TiN transition layers 3 is 3, and the time of a single layer is 5min;

a radio frequency ion source is used as a sputtering power supply of a C target, the power of the ion source is 1200W, the voltage of the C target is 1300V, the frequency of a workpiece rotating frame is 9 r/min, and the coating temperature is 150 ℃; the number of the amorphous carbon film layers 4 is 4, and the single-layer time is 30min.

Example 2:

step 01, performing steam cleaning on the metal bipolar plate 1, enabling the workpiece to enter a steam furnace, enabling the pressure of a steam outlet to be 0.8Mpa, the temperature in the steam furnace to be 100 ℃, enabling the cleaning time to be 30min, enabling the workpiece to exit the steam furnace, then enabling the workpiece to enter a pure water slow-drawing groove, finally enabling the workpiece to enter an oven for baking, and enabling the workpiece to be baked for 20min at the temperature of 130 ℃.

Step 02, placing the baked metal bipolar plate 1 into a vacuum furnace, and controlling the background vacuum degree in the vacuum furnace to be 2.5 x 10 ^-3 Drying the metal bipolar plate 1 for 60min at the temperature of Pa and 300 ℃;

step 03, introducing argon gas with the flow of 400sccm into the vacuum furnace to enable the vacuum degree in the vacuum furnace to be 1.8Pa, setting the power of the ion source to be 1000W, the voltage to be 1250V, the target current to be 0.2A, the target voltage to be 350V, the bias voltage of a workpiece to be 500V, the duty ratio to be 30 percent, the frequency of the workpiece rotating frame to be 9 r/min, and cleaning the ions of the metal bipolar plate 1 for 60min;

step 04, closing argon, workpiece bias voltage, ion source and target source, and vacuumizing until the vacuum degree in the vacuum furnace is 3.6 x 10 ^- ³ Pa；

Step 05, introducing argon gas of 500sccm, adopting a high-power medium-frequency power supply as a sputtering power supply of the Ti target, wherein the target current is 40A, the target voltage is 450V, the workpiece bias voltage is-200V, the duty ratio is 30%, the workpiece rotating frequency is 9 r/min, and the coating temperature is 300 ℃; the number of the Ti base layer 2 is 2, and the single-layer time is 3min;

introducing 50sccm of nitrogen, controlling the target current to be 40, the target voltage to be 500, the bias voltage of the workpiece to be 50V below zero, the duty ratio to be 80 percent, the frequency of the workpiece rotating frame to be 9 r/min and the coating temperature to be 300 ℃; the number of the TiN transition layers 3 is 5, and the time of a single layer is 10min;

a radio frequency ion source is adopted as a sputtering power supply of a C target, the power of the ion source is 1400W, the voltage of the C target is 1450V, the frequency of a workpiece rotating frame is 9 r/min, and the coating temperature is 300 ℃; the number of the amorphous carbon film layers 4 is 8, and the single-layer time is 30min.

And (4) performance testing:

1. surface contact resistance test

The metal bipolar plates obtained in examples 1 and 2 were subjected to surface contact resistance tests, respectively, and the surface contact resistances of the untreated metal bipolar plates were compared as blank tests, and the test results at a pressure of 1.5Mpa were as follows:

table 1 shows the results of the surface contact resistance tests of examples 1 and 2 and a blank set

Sample numbering	Contact resistance (m omega cm) ² )
		Example 1	5.2
Example 2	4.8
		Blank set (316L substrate)	9.7

As can be seen from table 1, the surface contact resistance of the metal bipolar plate treated by the preparation process of the present invention is significantly reduced compared to the untreated metal bipolar plate blank.

2. Test of Corrosion resistance

Potential scans were performed on the generic bipolar plates prepared in examples 1 and 2, as well as on untreated metallic bipolar plates, using a linear potential scan, at a scan rate of 1mV/s, over a potential scan range of-0.3V to 1.5V (vs. SCE), with the following test results:

table 2 shows the results of the corrosion resistance tests of examples 1 and 2 and a blank set

Sample numbering	Corrosion current muA/cm ²	Corrosion potential V
			Example 1	0.54	0.219
Example 2	0.38	0.302
			Blank set (316L substrate)	0.89	-0.098

As can be seen from table 2, the corrosion current density of the metal bipolar plate treated by the preparation process of the present invention is significantly reduced compared to the blank 316L base material, the corrosion potential is also significantly increased and moves to the positive potential, and the corrosion resistance is greatly enhanced.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A preparation process of an ultralow-resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell is characterized by comprising the following steps of:

step 01, cleaning the metal bipolar plate, and then baking the metal bipolar plate in an oven;

step 03, introducing argon gas with the flow of 200-600sccm into the vacuum furnace to ensure that the vacuum degree in the vacuum furnace is 0.5-2.5Pa, adopting a C target as a target source of a radio frequency ion source, ensuring that the power of the ion source is 500-1000W, the voltage is 800V-1300V, the target current is 0.2-0.5A or the target voltage is 200-600V, the bias voltage of a workpiece is-300-600V, the duty ratio is 30-80%, the frequency of a workpiece rotating frame is 3-15 r/min, and carrying out ion cleaning on the metal bipolar plate for 30-60min;

Step 05, introducing argon into a vacuum furnace, adopting a plasma enhanced vacuum plane magnetron sputtering method to sequentially plate a Ti base layer, a TiN transition layer and an amorphous carbon film layer on the metal bipolar plate,

in the step 01, the metal bipolar plate is cleaned by ultrasonic waves, and is sequentially subjected to ultrasonic oil removing groove, spraying groove, ultrasonic pure water groove and pure water slow-pulling groove, then is baked in an oven, the baking temperature is 120-150 ℃, the baking time is 30-60min, the metal bipolar plate is cleaned by steam, a workpiece enters a steam oven, the pressure of a steam outlet is 0.5-1.2MP a, the temperature in the steam oven is 90-150 ℃, the cleaning time is 20-40min, the workpiece is discharged from the steam oven, is subjected to pure water slow-pulling groove, and finally is baked in the oven, the baking temperature is 120-150 ℃, and the baking time is 20-40min;

in the step 02, the drying temperature of the metal bipolar plate is 100-300 ℃, and the time is 30-60min;

in the step 05, the number of Ti base layers is 2-5, the single-layer time is 2-5min, the argon gas introduction flow is 200-600sccm, the target current is 20-40A, the target voltage is 300-600V, the workpiece bias voltage is-30 to-300V, the duty ratio is 30-80%, the workpiece rotating frame frequency is 3-15 r/min, and the coating temperature is 100-300 ℃; the number of TiN transition layer layers is 2-5, the single-layer time is 2-10min, the argon gas introduction flow is 20-120sccm, the target current is 20-40A, the target voltage is 300-600V, the workpiece bias voltage is-30 to-100V, the duty ratio is 30-80%, the workpiece rotating frame frequency is 3-15 r/min, and the coating temperature is 100-300 ℃; the amorphous carbon film has 4-10 layers, the single-layer time is 20-60min, a radio frequency ion source is adopted as a sputtering power supply of a C target, the ion source power is 800-1500W, the corresponding C target voltage is 800-1500V, the workpiece rotating frame frequency is 6-15 r/min, and the coating temperature is 100-300 ℃.

2. The process for preparing an ultra-low resistance corrosion-resistant coating for a metal bipolar plate of a hydrogen fuel cell as claimed in claim 1, wherein in step 05, a high-power and high-frequency power source is used as a sputtering power source, the frequency of the high-power and high-frequency power source is 40-120KHz, and the power of the high-power and high-frequency power source is 40-60KW.