Surface treatment method for enhancing hydrogen permeation stability of interface between 316L stainless steel and Pd film

Abstract

The invention relates to the technical field of metal material surface treatment, in particular to a surface treatment method for enhancing hydrogen permeation stability of an interface of 316L stainless steel and a Pd film. According to the method, before a Pd film is deposited on the surface of a 316L stainless steel substrate, the 316L stainless steel substrate is sequentially subjected to mechanical grinding, polishing treatment and Ar plasma etching cleaning. According to the method, mechanical grinding and polishing and Ar plasma etching and cleaning methods are utilized, surface smoothing and oxide layer removing modification treatment of the 316L stainless steel substrate are achieved, the surface of the 316L stainless steel substrate is smooth and clean on the basis that the overall performance of the material is not changed, the bonding performance of the surface of the 316L stainless steel substrate and a hydrogen separation Pd film is remarkably improved, and the service life of the hydrogen separation Pd film is prolonged. And the service life and the service stability of the Pd film in a long-term hydrogen permeation environment are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment of metal materials, and in particular to a surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film. Background Art

[0002] Due to its low price, excellent mechanical properties, strong corrosion resistance, good compatibility with Pd film, and easy welding and assembly with other components, 316L stainless steel is an ideal support material for current hydrogen separation Pd film and is widely used in the fields of nuclear energy and hydrogen energy. However, after hydrogen permeation, the bonding force between the Pd film and the metal support material is poor, which affects the service life and long-term service stability of the Pd film. Summary of the Invention

[0003] In view of this, the purpose of the present invention is to provide a surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film. The method of the present invention can solve the problem of poor bonding force between the hydrogen separation Pd film and the 316L stainless steel support material in a hydrogen permeation environment.

[0004] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0005] The present invention provides a surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film, including the following steps:

[0006] Before depositing the Pd film on the surface of the 316L stainless steel substrate, the 316L stainless steel substrate is first subjected to mechanical grinding, polishing treatment, and Ar plasma etching and cleaning in sequence.

[0007] Preferably, the mechanical grinding includes: grinding with 320#, 800#, 1200#, and 2000# sandpapers in sequence.

[0008] Preferably, the surface roughness of the 316L stainless steel substrate after the polishing treatment is within Ra0.05.

[0009] Preferably, the conditions of the Ar plasma etching and cleaning include: the bias voltage is -500 to -600V, the argon gas flow rate is 30 to 50 sccm, the working gas pressure is 4 to 5 Pa, and the cleaning time is 30 to 40 min.

[0010] Preferably, the polishing treatment includes: polishing the 316L stainless steel substrate with W1.5 and W0.5 diamond grinding pastes in combination with a velvet polishing cloth in sequence.

[0011] Preferably, the polishing duration under each particle size of diamond grinding paste is independently 10 to 20 min, and the rotation speed of the polishing machine is independently 600 to 1000 r / min.

[0012] Preferably, before the mechanical grinding and before the polishing treatment, it further includes performing a first ultrasonic cleaning on the 316L stainless steel substrate after mechanical grinding.

[0013] Preferably, after the polishing treatment, it further includes performing a second ultrasonic cleaning on the 316L stainless steel substrate after polishing.

[0014] Preferably, after the second ultrasonic cleaning, it further includes wiping and cleaning the 316L stainless steel substrate after the second ultrasonic cleaning with deionized water, then performing a third ultrasonic cleaning and purging and cleaning with high-pressure dry nitrogen, and finally performing a vacuum drying treatment.

[0015] Preferably, during the mechanical grinding, grinding is carried out with the next grit size sandpaper after the scratches of the previous grit size sandpaper disappear, and the grinding directions of adjacent grit size sandpapers are at 90°; the grinding operation with each grit size sandpaper is repeated at least 3 times.

[0016] The present invention provides a surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film, including the following steps: before depositing a Pd film on the surface of a 316L stainless steel substrate, first sequentially perform mechanical grinding, polishing treatment, and Ar plasma etching and cleaning on the 316L stainless steel substrate. The applicant's research found that a natural oxide film is extremely easy to form on the surface of the 316L stainless steel substrate, and the presence of the oxide film will significantly affect the bonding force between the substrate and the Pd film interface, ultimately affecting the service life and long-term service stability of the Pd film. The present invention first removes the contaminants and oxide layer on the surface of the 316L stainless steel substrate through mechanical grinding treatment to obtain the original state of the 316L stainless steel material; then performs a polishing treatment on the surface of the 316L stainless steel substrate after mechanical grinding to remove the scratches and burrs left by mechanical grinding, achieving a smooth and bright effect; then performs Ar plasma etching and cleaning on the polished 316L stainless steel substrate. During the etching process, high-energy particles in the plasma can remove impurities such as contaminants and oxide layers on the substrate surface, further improving the quality of the substrate surface and providing a better substrate surface for subsequent Pd film deposition. After the surface of the 316L stainless steel substrate is treated by the method of the present invention and then a Pd film is deposited, the hydrogen permeation stability of the Pd film is greatly improved. Description of the Drawings

[0017] Figure 1 XRD patterns of the surface phase compositions of 316L stainless steel substrates treated by different methods;

[0018] Figure 2For the depth distribution of surface elements of 316L stainless steel substrates treated by different methods, where (a) is the original 316L stainless steel, (b) is Ar plasma sputtering etching, (c) is mechanical polishing, and (d) is thermal oxidation treatment;

[0019] Figure 3 For the microstructure morphology characteristics of Pd films deposited on the surfaces of 316L stainless steel substrates treated by different methods, where (a) is the original 316L, (b) is Ar plasma sputtering etching, (c) is mechanical polishing, and (d) is thermal oxidation treatment;

[0020] Figure 4 For the XRD patterns of Pd films on the surfaces of 316L stainless steel substrates treated by different methods;

[0021] Figure 5 For the surface morphology characteristics of Pd films deposited on the surfaces of 316L stainless steel substrates treated by different methods after hydrogen permeation, where (a - d) are the surface morphologies of Ar ion etching, mechanical polishing, original 316L, and thermally oxidized 316L Pd - coated samples after continuous hydrogen permeation for 6 h, (a 1 -d 1 ) are the surface morphologies of Ar ion etching, mechanical polishing, original 316L, and thermally oxidized 316L Pd - coated samples after continuous hydrogen permeation for 6 h. Specific embodiments

[0022] The present invention provides a surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film, including the following steps:

[0023] Before depositing the Pd film on the surface of the 316L stainless steel substrate, first perform mechanical grinding, polishing treatment, and Ar plasma etching cleaning on the 316L stainless steel substrate in sequence.

[0024] In the present invention, unless otherwise specified, the raw materials and equipment used are all well - known commercially available products in the art.

[0025] The present invention has no special requirements for the chemical composition of the 316L stainless steel substrate, and any well - known 316L stainless steel substrate in the art can be used. The present invention has no special requirements for the size of the 316L stainless steel substrate, and any well - known size can be used. In the embodiments of the present invention, the size is 10 mm×10 mm×1 mm.

[0026] In the present invention, due to natural placement, a natural oxide film will form on the surface of the 316L stainless steel substrate, which affects the hydrogen permeation stability of the Pd film. Specifically, after hydrogen permeation, the Pd film is likely to fall off from the surface of the 316L stainless steel substrate.

[0027] The present invention first performs mechanical grinding on the 316L stainless steel substrate.

[0028] In the present invention, the mechanical grinding preferably includes: grinding successively with 320#, 800#, 1200# and 2000# sandpapers; during the mechanical grinding, after the scratches of the previous grade sandpaper disappear, then grind with the next grade sandpaper, and the grinding directions of adjacent grade sandpapers are 90°; the grinding operation of each grade sandpaper is repeated at least 3 times. By using sandpapers with different mesh numbers, the present invention can effectively remove the natural oxide layer on the surface of the 316L stainless steel substrate, obtain the organizational structure of the 316L stainless steel material itself, and at the same time can remove the uneven parts on the surface, making the sample surface smoother and having a higher processing efficiency.

[0029] After completing the mechanical grinding, the present invention preferably performs the first ultrasonic cleaning on the mechanically ground 316L stainless steel substrate.

[0030] In the present invention, the first ultrasonic cleaning preferably uses petroleum ether and absolute ethanol for cleaning in sequence, each cleaning for 20 min, and after cleaning, change to new petroleum ether and absolute ethanol to continue cleaning, and cycle the operation twice. After the first ultrasonic cleaning is completed, the present invention preferably purges and cleans with high-pressure dry nitrogen, and then performs the polishing treatment.

[0031] In the present invention, the polishing treatment preferably includes: polishing the 316L stainless steel substrate successively with W1.5 and W0.5 diamond grinding pastes combined with a velvet polishing cloth; the polishing duration under each particle size of diamond grinding paste is independently preferably 10 - 20 min, and the rotation speed of the polishing machine is independently preferably 600 - 1000 r / min.

[0032] During the polishing treatment in the present invention, a uniform and stable force is maintained to avoid over-polishing or under-polishing. At the same time, deionized water is continuously dropped onto the 316L stainless steel substrate to reduce the temperature and increase the lubrication performance between the 316L stainless steel surface and the polishing cloth.

[0033] In the present invention, the surface roughness of the 316L stainless steel substrate after the polishing treatment is preferably within Ra0.05. The present invention modifies and deburrs the surface of the 316L stainless steel substrate through the polishing treatment, removes the grinding marks left by the mechanical grinding process, improves the surface finish, and reduces the surface roughness, having the advantages of high efficiency and thorough polishing and deburring.

[0034] After completing the polishing treatment, the present invention preferably further includes performing the second ultrasonic cleaning on the polished 316L stainless steel substrate. In the present invention, the second ultrasonic cleaning preferably uses petroleum ether and absolute ethanol for cleaning in sequence, each cleaning for 20 min, and after cleaning, change to new petroleum ether and absolute ethanol to continue cleaning, and cycle the operation twice.

[0035] After completing the second ultrasonic cleaning, the present invention preferably further includes wiping and cleaning the 316L stainless steel substrate after the second ultrasonic cleaning with deionized water, then performing a third ultrasonic cleaning and purging with high-pressure dry nitrogen using anhydrous ethanol, and finally performing a vacuum drying treatment.

[0036] In the present invention, the wiping and cleaning with deionized water preferably includes: wetting a lint-free cloth with deionized water, and then gently wiping the surface of the 316L stainless steel substrate with the wetted lint-free cloth. In the present invention, a uniform force should be maintained during wiping to avoid surface scratches caused by excessive force.

[0037] In the present invention, the temperature of the vacuum drying treatment is preferably 50 °C.

[0038] After the vacuum drying treatment is completed, the present invention performs Ar plasma etching cleaning on the polished 316L stainless steel substrate.

[0039] In the present invention, the conditions for the Ar plasma etching cleaning preferably include: a bias voltage of -500 to -600 V, an argon gas flow rate of 30 to 50 sccm, a working gas pressure of 4 to 5 Pa, and a cleaning time of 30 to 40 min. In specific embodiments of the present invention, the bias voltage can be -500 V, -530 V, -550 V, -580 V, or -600 V, the argon gas flow rate can be 30 sccm, 35 sccm, 40 sccm, 45 sccm, or 50 sccm, the working gas pressure can be 4 Pa, 4.5 Pa, or 5 Pa, and the cleaning time can be 30 min, 35 min, or 40 min.

[0040] Through the Ar plasma etching cleaning, the present invention can further remove various contaminants on the surface of the 316L stainless steel substrate, including organic substances, oxides, and micro-particle contaminants, etc. Through the etching of Ar ions, these contaminants are separated and removed from the sample surface to obtain a smoother and cleaner surface.

[0041] The following describes in detail the surface treatment method for enhancing the hydrogen permeation stability at the interface between 316L stainless steel and Pd film provided by the present invention with reference to embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0042] In other embodiments, the 316L stainless steel can be cut into other sizes and stainless steel materials with other components can be used, which does not affect the implementation of the surface treatment method of the present invention.

[0043] Example 1

[0044] Step 1: Cut a commercial 316L stainless steel plate into pieces with dimensions of 10 mm × 10 mm × 1 mm by wire cutting. In this example, the composition of the 316L stainless steel substrate by mass percentage includes: Fe 62.49%, Mo 3.00%, Ni 14.00%, Mn 1.8%, P 0.03%, S 0.02%, Cr 18.00%, Si 0.63%, and C 0.03%.

[0045] Step 2: Polish successively with 320#, 800#, 1200#, and 2000# sandpapers. When polishing, the scratches are parallel to the polishing direction. After the scratches of the previous process disappear, rotate the sample by 90° so that the polishing slip direction is perpendicular to the previous scratches by 90°. Stop polishing after the scratches of the previous process disappear. Repeat the operation 3 times for each type of sandpaper polishing. Subsequently, change to a sandpaper with a larger mesh number for polishing and repeat the above steps until the mechanical polishing step is completed after polishing with 2000# sandpaper.

[0046] Step 3: Ultrasonically clean the 316L stainless steel substrate successively with petroleum ether and absolute ethanol, each cleaning for 20 min. After cleaning, change to new petroleum ether and absolute ethanol for continuous cleaning, and perform the cyclic operation twice. Subsequently, blow and clean with high-pressure dry nitrogen.

[0047] Step 4: Polish the surface of the 316L stainless steel substrate successively with W1.5 and W0.5 diamond grinding pastes combined with ordinary velvet polishing cloth. The polishing duration is 10 min for each particle size of the polishing paste, and the rotation speed of the polishing machine is 600 r / min. Maintain a uniform and stable force during the polishing process to avoid over-polishing or under-polishing. At the same time, continuously drip deionized water onto the 316L stainless steel to reduce the temperature and increase the lubrication performance between the surface of the 316L stainless steel and the polishing cloth, so that the surface roughness reaches Ra0.02. After polishing, clean the 316L stainless steel substrate, and ultrasonically clean successively with petroleum ether and absolute ethanol, with each cleaning time controlled above 20 min, and perform the cyclic operation twice.

[0048] Step 5: Gently wipe the surface of the polished 316L stainless steel substrate with a moistened dust-free cloth to ensure that there are no stains on the surface. Moisten the dust-free cloth with deionized water, and keep a uniform force when wiping to avoid scratching the surface due to excessive force. Subsequently, ultrasonically clean the 316L stainless steel substrate with absolute ethanol and blow and clean with high-pressure dry nitrogen, and finally place it in a vacuum drying oven for drying treatment at 50 °C in a vacuum environment.

[0049] Step 6: Perform argon plasma etching and cleaning on the surface of the 316L stainless steel substrate. Place the 316L stainless steel substrate in the vacuum chamber of the magnetron sputtering system and introduce argon gas. Apply a bias voltage of -500 V to the substrate, with an argon gas flow rate of 40 sccm, a working gas pressure maintained at 4 Pa, and a cleaning time of 30 min to ensure the removal of contaminants, oxide layers, and other impurities on the substrate surface.

[0050] To verify the effect of the surface treatment method of the present invention on improving the hydrogen permeation stability at the interface between the Pd film and the 316L stainless steel, in this embodiment, tests on the phase composition, elemental concentration depth distribution of the surface of the 316L stainless steel substrate before and after surface treatment, and the hydrogen permeation stability at the interface between the 316L stainless steel and the Pd film after depositing the Pd film were carried out.

[0051] Comparative example

[0052] Perform thermal oxidation treatment on 316L stainless steel. Specifically, at a heating rate of 10 °C / min, perform thermal oxidation treatment on 316L stainless steel in an air atmosphere at 530 K for 10 h.

[0053] Test 1:

[0054] Use an X-ray diffractometer (XRD) to analyze the phase composition of the surface of the 316L stainless steel substrate before and after the surface treatment in Example 1. The results are as Figure 1 shown. Figure 1 In it, Thermal oxidation represents 316L stainless steel after thermal oxidation treatment, Mechanicalpolishing represents 316L stainless steel after mechanical grinding and polishing (hereinafter referred to as mechanical polishing), Arplasma etching represents 316L stainless steel after Ar ion etching, and Original SS316L represents the original 316L stainless steel. It can be seen from Figure 1 that on the surface of the original 316L stainless steel, not only the characteristic diffraction peaks of 316L stainless steel exist, but also the phase of Fe 3 O 4 exists. After Ar ion etching and mechanical polishing, only the characteristic diffraction peaks of 316L stainless steel exist. On the surface of the 316L stainless steel after thermal oxidation treatment, in addition to its own characteristic peaks, the diffraction peaks of the Fe 2 O 3 / Cr 2 O 3 mixed phase also exist.

[0055] Test 2:

[0056] The 316L stainless steel surfaces before and after surface treatment were analyzed by glow discharge optical emission spectrometry (GDOES). During the measurement, the sample itself served as the cathode, the anode was grounded, the gas pressure in the GDOES system was maintained at 650 Pa, the power was set at 7.5 W, and the sample stage was cooled by liquid nitrogen to prevent the escape of deuterium in the material at high temperatures. The measurement area was 0.196 cm 2 , and the measured elemental concentration depth profiles are as shown in Figure 2 . Figure 2 . In Figure 2 , (a) - (d) are the elemental depth profiles of the surfaces of the original 316L stainless steel, mechanical polishing combined with Ar plasma sputtering etching, mechanical polishing, and thermal oxidation treated 316L stainless steel substrates in sequence. As can be seen from

[0057] Experiment 3:

[0058] A Pd film was deposited on the surface of the surface-treated 316L stainless steel substrate. The Pd film deposition method was as follows: magnetron sputtering (MS) deposition technology was used to prepare a Pd film on the substrate surface. The argon flow rate was 40 sccm, the working gas pressure was maintained at 0.75 Pa, the substrate bias voltage was -100 V, the target was a Pd target with a purity of 99.95%, the power supply used was a DC power supply, the target power was 100 W, the deposition time was 65 min, and the temperature was 150 °C. The surface morphology of the Pd film was observed using a scanning electron microscope (SEM), and the results are as shown in Figure 3 . Figure 3 . In Figure 3 , they are the surface morphologies of the Pd films on the surfaces of the original 316L (a), Ar plasma sputtering etched (b), mechanically polished (c), and thermally oxidized treated (d) 316L stainless steel substrates respectively. As can be seen from

[0059] Experiment 4:

[0060] The phase composition analysis was carried out on the Pd film deposited on the 316L stainless steel substrate, and the obtained XRD pattern is as shown in Figure 4As shown. Obvious diffraction peaks appear at 40.2°, 46.7°, 68.3°, 82.3° and 86.8° on the Pd films on the surfaces of 316L stainless steel substrates with different surface treatments, corresponding to the (111), (200), (220), (311), (222) crystal planes of Pd respectively, and the intensities and widths of the diffraction peaks are basically the same.

[0061] Experiment Five:

[0062] Samples of Pd films deposited on the surfaces of 316L stainless steel substrates with different surface treatments were subjected to hydrogen permeation stability tests. The specimens were fixed on a gas-driven permeation platform, and steady-state hydrogen permeation tests were carried out for 6 h and 30 h in the temperature range of 400 °C when the upstream hydrogen pressure was 100 kPa. The surface morphology after permeation was observed by SEM, and the results are shown in Figure 5 , Figure 5 in (a-d) and (a 1 -d 1 ) are Pd-coated samples of Ar ion etching, mechanical polishing, as-received 316L, and thermal oxidation 316L respectively; the first row and the second row represent the surface morphologies after continuous hydrogen permeation for 6 h and 30 h respectively. As Figure 5 shown, a small number of bubbles appeared on the Pd on the surface of as-received 316L stainless steel (see Figure 5 in c), and the density and size of the bubbles increased with time (see Figure 5 in c 1 ). The Pd on the surfaces of 316L stainless steel treated by Ar ion etching and mechanical polishing remained smooth and flat after 6 h and 30 h of hydrogen permeation, and no bubbles appeared. After 6 h of hydrogen permeation on the Pd on the surface of 316L stainless steel treated by thermal oxidation, a large number of small bubbles appeared on the surface (see Figure 5 in d). As the hydrogen permeation time increased to 30 h, the Pd film on the substrate surface had completely peeled off (see Figure 5 in d 1 ). It can be seen that the method of mechanical polishing combined with Ar plasma etching and cleaning treatment on the surface of 316L stainless steel proposed by the present invention effectively solves the problem of long-life hydrogen permeation stability at the interface between 316L stainless steel and the Pd film.

[0063] Example 2

[0064] Step 1: Cut commercial 316L stainless steel plates into pieces with dimensions of 10 mm × 10 mm × 1 mm by wire cutting. In this example, the composition of 316L stainless steel by mass percentage includes: Fe 70.99%, Mo 2.00%, Ni 10.00%, Mn 1.3%, P 0.02%, S 0.01%, Cr 15.30%, Si 0.37% and C 0.01%

[0065] Step 2: Polish successively with 320#, 800#, 1200#, and 2000# sandpapers. When polishing, the scratches should be parallel to the polishing direction. After the scratches from the previous process disappear, rotate the sample by 90°, so that the polishing slip direction is perpendicular to the previous scratches at 90°. Stop polishing after the scratches from the previous process disappear. Repeat the operation 3 times for each type of sandpaper. Subsequently, change to a sandpaper with a larger mesh number and repeat the above steps until the mechanical polishing step is completed after polishing with 2000# sandpaper.

[0066] Step 3: Ultrasonically clean the 316L stainless steel substrate successively with petroleum ether and absolute ethanol for 20 minutes each time. After cleaning, change to new petroleum ether and absolute ethanol and continue cleaning, and perform the cyclic operation twice. Subsequently, blow and clean with high-pressure dry nitrogen.

[0067] Step 4: Polish the surface of the 316L stainless steel substrate successively with W1.5 and W0.5 diamond grinding pastes combined with ordinary velvet polishing cloth. The polishing duration is 20 minutes for each particle size of the polishing paste, and the rotation speed of the polishing machine is 1000 r / min. Maintain a uniform and stable force during the polishing process to avoid over-polishing or under-polishing. At the same time, continuously drip deionized water onto the 316L stainless steel to reduce the temperature and increase the lubrication performance between the surface of the 316L stainless steel and the polishing cloth, so that the surface roughness reaches Ra0.05. After polishing, clean the 316L stainless steel substrate, and ultrasonically clean it successively with petroleum ether and absolute ethanol, with each cleaning time controlled to be more than 20 minutes, and perform the cyclic operation twice.

[0068] Step 5: Gently wipe the surface of the polished 316L stainless steel substrate with a wet dust-free cloth to ensure that the surface is free of stains, etc. Wet the dust-free cloth with deionized water, and maintain a uniform force during wiping to avoid scratching the surface due to excessive force. Subsequently, ultrasonically clean the 316L stainless steel substrate with absolute ethanol and blow and clean it with high-pressure dry nitrogen, and finally place it in a vacuum drying oven for drying treatment at 50°C in a vacuum environment.

[0069] Step 6: Perform argon plasma etching and cleaning on the surface of the 316L stainless steel substrate. Place the 316L stainless steel substrate in the vacuum chamber of the magnetron sputtering system and introduce argon gas. Apply a bias voltage of -600V to the substrate, the flow rate of argon gas is 40 sccm, the working pressure is maintained at 5 Pa, and the cleaning time is 40 minutes to ensure the removal of impurities such as pollutants and oxide layers on the substrate surface.

[0070] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be regarded as the protection scope of the present invention.

Claims

1. A surface treatment method for enhancing the hydrogen permeation stability of the interface between 316L stainless steel and Pd film, characterized in that: The following steps are involved: Before depositing the Pd film on the surface of the 316L stainless steel substrate, the 316L stainless steel substrate is first subjected to mechanical grinding, polishing and Ar plasma etching cleaning in sequence.

2. The surface treatment method according to claim 1, characterized in that: The mechanical grinding includes: using 320#, 800#, 1200# and 2000# sandpaper for grinding in sequence.

3. The surface treatment method according to claim 1, characterized in that: The roughness of the surface of the 316L stainless steel substrate after the polishing treatment is within Ra0.

05.

4. The surface treatment method according to claim 1, characterized in that: The conditions for the Ar plasma etching cleaning include: a bias voltage of -500 to -600 V, an argon gas flow rate of 30 to 50 sccm, a working gas pressure of 4 to 5 Pa, and a cleaning time of 30 to 40 minutes.

5. The surface treatment method according to claim 1 or 3, characterized in that: The polishing process includes: polishing the 316L stainless steel substrate with W1.5 and W0.5 diamond grinding pastes in combination with velvet polishing cloth in sequence.

6. The surface treatment method according to claim 5, characterized in that: The polishing time of each particle size of diamond paste is independently 10 to 20 minutes, and the polishing machine speed is independently 600 to 1000 r / min.

7. The surface treatment method according to claim 1 or 2, characterized in that: The method also includes performing a first ultrasonic cleaning on the mechanically ground 316L stainless steel substrate before the polishing process.

8. The surface treatment method according to claim 1 or 3, characterized in that: After the polishing treatment, the method further includes performing a second ultrasonic cleaning on the polished 316L stainless steel substrate.

9. The surface treatment method according to claim 8, characterized in that: After the second ultrasonic cleaning, the 316L stainless steel substrate after the second ultrasonic cleaning is wiped with deionized water, and then anhydrous ethanol is used for a third ultrasonic cleaning and a high-pressure dry nitrogen purge cleaning, and finally a vacuum drying treatment is performed.

10. The surface treatment method according to claim 2, characterized in that: During the mechanical grinding, the next type of sandpaper is used for grinding after the scratches of the previous type of sandpaper disappear, and the grinding directions of adjacent types of sandpaper are 90 degrees; the grinding operation of each type of sandpaper is repeated at least 3 times.

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