A multilayer strongly corrosion-resistant coating for a PEM electrolysis cell bipolar plate and a method for its production

Abstract

The application discloses a multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate and a preparation method thereof, and belongs to the technical field of coating preparation. The TaN layer and the Ta layer are alternately deposited on the surface of a titanium plate substrate through a direct current reaction magnetron sputtering technology, and the outermost layer is covered with a PtTaN layer, so as to form a Ta / TaN / PtTaN multilayer coating. The TaN layer and the Ta layer break the growth of columnar crystals by using the interface, and a dense corrosion-resistant coating is prepared. The surface of the outermost layer coated with the PtTaN coating is dense and smooth. Because a small amount of noble metal Pt is added, the outermost layer has good corrosion resistance, electrical conductivity and hydrophobicity, and has application potential in the development of PEM bipolar plate coatings.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating preparation, and particularly relates to a multilayer strong corrosion-resistant coating for PEM electrolytic cell bipolar plates and a preparation method thereof. BACKGROUND

[0002] Proton exchange membrane electrolyzer (PEM WE) has the advantages of high energy conversion efficiency and small pollution. The bipolar plate is a key component of the PEM WE, accounting for more than 50% of the cost of the electric pile. The bare metal bipolar plate is easily corroded under the working conditions of high potential, strong oxidation and strong corrosion of the PEM WE. The metal ions dissolved by corrosion can cause poisoning of the membrane electrode, and the high ICR value of the surface oxidation layer can also cause large power loss of the electrolytic cell. Therefore, it is urgent to develop a bipolar plate surface coating with high conductivity and strong corrosion resistance, which can reduce anode oxidation and corrosion without compromising conductivity, and protect the bipolar plate. Noble metal coatings (such as Au, Ag, Pt) have excellent conductivity and corrosion resistance, but are high in cost and limited in reserves, which are not suitable for large-scale industrial application. In contrast, transition metals (Ti, Cr, Zr, Ni, Mo, Ta, etc. Group IV-VI B elements) and their nitrides are lower in cost and have excellent conductivity and corrosion resistance. In particular, tantalum (Ta) is easy to form tantalum pentoxide (Ta2O5) on the surface, which is extremely impermeable to water, making its chemical inertness and corrosion resistance comparable to noble metals. As a refractory ceramic, tantalum nitride (TaN) has high chemical stability and similar metal conductivity. Depositing a single layer of Ta or TaN coating on the metal substrate by magnetron sputtering and other methods often provides a fast channel for corrosive ions in the electrolyte, which adversely affects the corrosion resistance of the bipolar plate. The alternating deposition of Ta and TaN coatings forms a multilayer structure that can cut off the columnar crystals, inhibit the penetration of corrosive electrolyte, and improve the corrosion resistance of the bipolar plate material, but the increased interface contact resistance will increase the energy consumption of the PEM electrolytic cell. SUMMARY

[0003] The present application aims to overcome the shortcomings of the prior art and provide a multilayer strong corrosion-resistant coating for PEM electrolytic cell bipolar plates and a preparation method thereof to solve the problem of high energy consumption of the alternating deposition of Ta and TaN coatings in the prior art. The present application prepares a Ta / TaN / Pt TaN multilayer composite coating on the surface of a metal substrate by direct current reactive magnetron sputtering technology. The multilayer interface cuts off the columnar crystals, the surface is dense and smooth, has good corrosion resistance and hydrophobicity, and has potential in the development and application of PEM bipolar plate coatings.

[0004] To achieve the above-mentioned purpose, the technical scheme of the present application is adopted to achieve the above-mentioned purpose.

[0005] A multilayer strong corrosion-resistant coating for PEM electrolytic cell bipolar plate, comprising an alternating layer, a sub-outer layer and an outermost layer arranged in the metal substrate surface of the electrolytic cell bipolar plate from inside to outside;

[0006] The alternating layer is an alternating Ta layer and TaN layer, and the outer layer of the alternating layer is a Ta layer;

[0007] The sub-outer layer is TaN;

[0008] The outermost layer is a PtTaN layer.

[0009] Preferably, the thickness of the coating is ≤3μm.

[0010] A preparation method of a multilayer strong corrosion-resistant coating for PEM electrolytic cell bipolar plate, comprising the following steps:

[0011] Step 1, depositing a Ta layer and a TaN layer alternately on the metal substrate by magnetron sputtering, and the last deposition is a Ta layer;

[0012] Step 2, depositing a sub-outer layer on the Ta layer by magnetron sputtering, the sub-outer layer is a TaN layer;

[0013] Step 3, depositing an outermost layer on the sub-outer layer by magnetron sputtering, the outermost layer is a PtTaN layer.

[0014] Preferably, before step 1, the metal substrate is polished, mirror polished and ultrasonically cleaned.

[0015] Preferably, in step 1, the process parameters for depositing the Ta layer are: vacuum degree 6.6×10 -4 Pa, argon flow rate 20sccm, working pressure 0.57-0.77Pa, sputtering power 80-100W, sputtering time 15-45min, and substrate heating temperature 150-350℃.

[0016] Preferably, in step 1 and step 2, the process parameters for depositing the TaN layer are: vacuum degree 6.6×10 -4 Pa, argon flow rate 20sccm, nitrogen flow rate 2-4sccm, working pressure 0.57-0.77Pa, sputtering power 80-100W, sputtering time 15-45min, and substrate heating temperature 150-350℃.

[0017] Preferably, in step 3, the conditions for depositing the PtTaN layer are: direct current sputtering of a Pt-Ta alloy target, argon flow rate 20sccm, nitrogen flow rate 2-4sccm, working pressure 0.57-0.77Pa, sputtering power 80-100W, sputtering time 15-35min, and substrate heating temperature 150-350℃.

[0018] Preferably, in step 3, the mass fraction of Pt element in the Pt-Ta alloy target is 10-20 wt.%.

[0019] Preferably, in step 1, the Ta layer and the TaN layer are alternately deposited 1-5 times.

[0020] Preferably, the target material during deposition of the Ta layer and the TaN layer is a Ta target.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The application discloses a preparation method of a multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate.

[0023] The application also discloses a multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate.

[0024] (1) Excellent corrosion resistance. The coating alternately arranges the multilayer TaN layer and the Ta layer, effectively blocks the longitudinal growth of columnar crystals, greatly reduces the corrosion current density of the bipolar plate sample in the simulated PEM electrolytic cell working environment, and has good corrosion resistance.

[0025] (2) Excellent conductivity. XRD spectrum shows that the (111) crystal face preferred orientation of the δ-TaN can promote the pseudo-epitaxial growth of the α-Ta layer with good corrosion resistance and conductivity. EDS spectrum shows that the coating is doped with Pt element, and the Pt element exists in the form of elemental particles, reduces the interface contact resistance on the basis of maintaining good corrosion resistance.

[0026] (3) excellent hydrophobic performance. Field emission SEM observation finds that the coating surface is complete, the crystal grains are closely arranged, and the adhesion of the coating to the titanium substrate is relatively strong. After mirror polishing, the hydrophilic titanium plate deposited coating reduces the surface roughness, the surface hydrophobicity is strong, can effectively reduce the aggregation of corrosive ions, and further improves the corrosion resistance of the sample. In summary, the application breaks the columnar crystal by depositing a multilayer composite coating by reactive magnetron sputtering, and prepares a dense corrosion-resistant coating. The coverage of the PtTaN coating makes the surface dense and smooth, has good corrosion resistance, conductivity and hydrophobicity, and has application potential in the development of PEM bipolar plate coating. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a schematic diagram of the multilayer coating structure prepared by the application;

[0028] Figure 2 is a scanning electron microscope image of the cross-sectional morphology of the coating of the application;

[0029] wherein (a) is Example 1; (b) is Comparative Example 1; (c) is Comparative Example 2;

[0030] Figure 3 is the potentiodynamic polarization curve of the coating sample and the titanium plate substrate of Example 1, Comparative Example 1 and Comparative Example 2 of the application;

[0031] Figure 4 is the XRD pattern of the coating of Example 1, Example 2, Comparative Example 1-Comparative Example 3 and the titanium plate substrate of the application;

[0032] wherein (a) is the XRD pattern of Example 1, Comparative Example 1, Comparative Example 2 and the titanium plate substrate;

[0033] (b) is the XRD pattern of Example 1, Example 2, Comparative Example 1 and Comparative Example 3;

[0034] Figure 5 is the EDS spectrum of the coating surface of Example 1 and Comparative Example 1 of the application;

[0035] wherein (a) is Example 1, (b) is Comparative Example 1;

[0036] Figure 6 is the XPS spectrum of the coating of Example 1 and Comparative Example 1 of the application;

[0037] wherein (a) is a comparison chart of Example 1 and Comparative Example 1; (b) is a fine spectrum.

[0038] Figure 7 is the corrosion resistance and conductivity performance histogram of the coating of Example 1 and Comparative Example 1-Comparative Example 2 of the application;

[0039] Figure 8are the real photos of the coating and the titanium plate substrate of the embodiment 1 and the comparative examples 1 to 2 of the application;

[0040] Figure 9 are the scanning electron microscope photos of the surface morphology of the coating and the titanium plate substrate of the embodiment 1 and the comparative examples 1 to 2 of the application;

[0041] Figure 10 are the surface roughness photos of the coating and the titanium plate substrate of the embodiment 1 and the comparative examples 1 to 2 of the application;

[0042] Figure 11 are the surface water contact angles of the coating and the titanium plate substrate of the embodiment 1 and the comparative examples 1 to 2 of the application. DETAILED DESCRIPTION

[0043] The application discloses a multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate.

[0044] The metal substrate of the PEM electrolytic cell bipolar plate is a Ti plate.

[0045] It should be understood that the coating directly contacting the surface of the bipolar plate can be a Ta layer or a TaN layer, but the outermost layer of the alternating layer needs to be a Ta layer, so as to be in contact with the TaN layer of the secondary outer layer and form an interface.

[0046] The application further discloses a preparation method of the Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for the PEM electrolytic cell bipolar plate.

[0047] In some embodiments of the application, the multilayer coating is deposited by using a direct current reaction magnetron sputtering technology, the target materials used are a Ta target (with a purity of 99.99%) and a Pt-Ta alloy target (with a mass percentage of 10-20 wt.% of Pt elements), and direct current sputtering is adopted. -4 The base vacuum degree is 6.6*10

[0048] More specifically, a method for preparing a Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate, comprising the following steps:

[0049] (1) polishing, mirror polishing and ultrasonic cleaning the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0050] (2) alternately depositing Ta and TaN layers;

[0051] (3) depositing a PtTaN layer on the TaN / Ta multilayer coating.

[0052] Preferably, in the step (2), the conditions for depositing the TaN layer are as follows: the base vacuum degree is 6.6*10 -4 Pa, the argon flow rate is 20 sccm, the nitrogen flow rate is 2-4 sccm, the working gas pressure is 0.57-0.77 Pa, the sputtering power is 80-100 W, the sputtering time is 15-45 min, and the substrate heating temperature is 150-350°C.

[0053] Preferably, in the step (2), the conditions for depositing the Ta layer are as follows: the nitrogen valve is closed, the argon flow rate is fixed at 20 sccm, the working gas pressure is 0.57-0.77 Pa, the sputtering power is 80-100 W, the sputtering time is 15-45 min, and the substrate heating temperature is 150-350°C.

[0054] Preferably, in the step (2), the Ta layer and the TaN layer are alternately deposited for 1-5 times.

[0055] Preferably, in the step (3), the conditions for depositing the PtTaN layer are as follows: a Pt-Ta alloy target is used for direct current sputtering, the argon flow rate is 20 sccm, the nitrogen flow rate is 2-4 sccm, the working gas pressure is 0.57-0.77 Pa, the sputtering power is 80-100 W, the sputtering time is 15-35 min, and the substrate heating temperature is 150-350°C.

[0056] Preferably, the deposition process is continuous heating.

[0057] The present application provides a method for preparing a Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate, i.e. depositing a Ta / TaN / PtTaN composite coating on the surface of a titanium plate substrate by direct current reactive magnetron sputtering technology. The present application prepares a multilayer composite coating, uses the interface to break the columnar crystal growth, and prepares a dense corrosion-resistant coating. After coating the outermost layer with a PtTaN coating, the surface is dense and smooth, and also has good corrosion resistance, electrical conductivity and hydrophobicity, and has application potential in the development of PEM bipolar plate coatings.

[0058] The application will be further described below with reference to specific examples and drawings.

[0059] Example 1

[0060] A Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0061] (1) Grind, mirror polish and ultrasonic clean the titanium plate substrate, and place the cleaned titanium substrate into a vacuum chamber;

[0062] (2) Alternately deposit Ta layers and TaN layers. S1. Deposit a TaN layer: the background vacuum degree is 6.6*10 -4 Pa, the argon flow rate is 20 sccm, the nitrogen flow rate is 3 sccm, the working gas pressure is 0.70 Pa, the sputtering power is 80 W, the sputtering time is 30 min, and the substrate heating temperature is 150°C; S2. Deposit a Ta layer: close the nitrogen valve, keep the argon flow rate at 20 sccm, the working gas pressure at 0.70 Pa, the sputtering power at 80 W, the sputtering time at 30 min, and the substrate heating temperature at 150°C; repeat the S1 step: open the nitrogen valve, adjust the nitrogen flow rate back to 3 sccm, control the working gas pressure at 0.70 Pa, and keep the other parameters consistent with S1;

[0063] (3) Deposit a PtTaN layer on the TaN / Ta multilayer coating. Replace the Ta target with a Pt-Ta alloy target, wherein the Pt element accounts for 15 wt.%, ensure the argon flow rate at 20 sccm, the nitrogen flow rate at 3 sccm, the working gas pressure at 0.70 Pa, the sputtering power at 80 W, the sputtering time at 25 min, and the substrate heating temperature at 150°C.

[0064] Example 2

[0065] A Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0066] (1) Grind, mirror polish and ultrasonic clean the titanium plate substrate, and place the cleaned titanium substrate into a vacuum chamber;

[0067] (2) Alternately deposit Ta layers and TaN layers. S1. Deposit a TaN layer: the background vacuum degree is 6.6*10 -4 Pa, the argon flow rate is 20 sccm, the nitrogen flow rate is 3 sccm, the working gas pressure is 0.70 Pa, the sputtering power is 80 W, the sputtering time is 30 min, and the substrate heating temperature is 150°C; S2. Deposit a Ta layer: close the nitrogen valve, keep the argon flow rate at 20 sccm, the working gas pressure at 0.70 Pa, the sputtering power at 80 W, the sputtering time at 30 min, and the substrate heating temperature at 150°C; repeat the S1 step: open the nitrogen valve, adjust the nitrogen flow rate back to 3 sccm, control the working gas pressure at 0.70 Pa, and keep the other parameters consistent with S1;

[0068] (3) Depositing a PtTaN layer on the TaN / Ta multilayer coating. The Ta target is replaced by a Pt-Ta alloy target with a Pt element proportion of 15 wt.%, the argon flow rate is fixed at 20 seem, the nitrogen flow rate is 3 seem, the working gas pressure is 0.70 Pa, the sputtering power is 80 W, the sputtering time is 25 min, and the substrate heating temperature is 150°C.

[0069] Example 3

[0070] A Ta / TaN / PtTaN multilayer corrosion-resistant coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0071] (1) Polishing, mirror polishing and ultrasonic cleaning the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0072] (2) Alternately depositing Ta layers and TaN layers, with the TaN layer on the outermost side. S1. Depositing a TaN layer: the background vacuum degree is 6.6x10 -4 Pa, the argon flow rate is 20 seem, the nitrogen flow rate is 4 seem, the working gas pressure is 0.63 Pa, the sputtering power is 90 W, the sputtering time is 20 min, and the substrate heating temperature is 150°C; S2. Depositing a Ta layer: the nitrogen valve is closed, the argon flow rate is kept at 20 seem, the working gas pressure is 0.63 Pa, the sputtering power is 90 W, the sputtering time is 20 min, and the substrate heating temperature is 150°C; sequentially repeating the S1, S2, S1, S2 and S1 steps;

[0073] (3) Depositing a PtTaN layer on the TaN / Ta multilayer coating. The Ta target is replaced by a Pt-Ta alloy target with a Pt element proportion of 15 wt.%, the argon flow rate is fixed at 20 seem, the nitrogen flow rate is 4 seem, the working gas pressure is 0.63 Pa, the sputtering power is 90 W, the sputtering time is 20 min, and the substrate heating temperature is 150°C.

[0074] Comparative Example 1

[0075] A Ta / TaN multilayer coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0076] (1) Polishing, mirror polishing and ultrasonic cleaning the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0077] (2) Alternately depositing Ta layers and TaN layers, with the TaN layer on the outermost side. S1. Depositing a TaN layer: the background vacuum degree is 6.6x10 -4S1. Depositing TaN layer: open the nitrogen valve, adjust the nitrogen flow to 3sccm, set the working pressure to 0.70 Pa, the sputtering power to 80 W, the sputtering time to 30 min, and the substrate heating temperature to 150℃, and keep the argon flow at 20sccm; S2. Depositing Ta layer: close the nitrogen valve, keep the argon flow at 20sccm, set the working pressure to 0.70 Pa, the sputtering power to 80 W, the sputtering time to 30 min, and the substrate heating temperature to 150℃; repeat the step S1: open the nitrogen valve, adjust the nitrogen flow to 3sccm, set the working pressure to 0.70 Pa, and keep the other parameters consistent with S1.

[0078] Comparative Example 2

[0079] A TaN coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0080] (1) polishing, mirror polishing and ultrasonic cleaning the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0081] (2) depositing a TaN layer. The base vacuum degree is 6.6*10 -4 Pa, the argon flow is 20sccm, the nitrogen flow is 3sccm, the working pressure is 0.70 Pa, the sputtering power is 80 W, the sputtering time is 90 min, and the substrate heating temperature is 150℃.

[0082] Comparative Example 3

[0083] Comparative Example 3 differs from Comparative Example 1 only in that in step (2), the deposition time of S1 and S2 steps is 18 min, and S1, S2, S1, S2 and S1 steps are sequentially and alternately performed, and the preparation method refers to Comparative Example 1.

[0084] The prepared titanium-based bipolar plate coating is characterized in terms of cross-sectional micro-morphology and phase structure, and surface contact resistance testing and electrochemical polarization testing are performed in a simulated PEM electrolytic cell working environment. Figure 1 is a schematic diagram of the multilayer coating structure prepared in Example 1 of the present application, and from bottom to top, there are a titanium plate substrate, a TaN layer, a Ta layer, a TaN layer and a PtTaN layer, wherein the Ta layer and the TaN layer are alternately deposited multiple times. Figure 2 The (a) figure-(c figure) in are scanning electron microscope images of the cross-sectional morphology of the coating of Example 1 and Comparative Examples 1-2 of the present application. Apparently, the cross-section of the single-layer TaN coating presents a clear columnar crystal structure, which provides a fast channel for corrosive ions in the electrolyte, adversely affecting the corrosion resistance of the bipolar plate; the TaN / Ta / TaN multilayer coating cuts off the columnar crystals, which helps to prevent the penetration of corrosive electrolyte and improves the overall corrosion resistance of the bipolar plate material; the bonding force between PtTaN and TaN is strong, and it has strong corrosion resistance and is also expected to enhance the interface conductivity. Figure 3are the potentiodynamic polarization curves of the coating and titanium plate substrate of Example 1 and Comparative Examples 1-2 of the present application. A standard three-electrode system was used, with the sample as the working electrode, a platinum electrode as the counter electrode, and a saturated calomel electrode (SCE) as the reference electrode. The test solution was 0.5 M H2SO4+2 ppm F - (analogous to the PEM electrolyzer environment), and the test temperature was 80℃. The open circuit potential (OCP) was first stabilized for 1.5 h, and then the potentiodynamic polarization (-0.5 V SCE ~ 2.8 V SCE ) curve of the sample was tested. The corrosion current density (I corr ) was calculated according to the Tafel slope. The results show that, compared with the titanium plate substrate without coating, Comparative Example 2 with a single-layer TaN coating has a higher self-corrosion potential (E corr ) and a lower corrosion current density (I corr and I 2V ). The self-corrosion potential (E corr ) of the TaN / Ta / TaN three-layer coating is further improved, and the corrosion current density (I corr ) is reduced by 2 and 4 orders of magnitude, respectively, based on Comparative Example 2 and the titanium plate substrate. The corrosion current density I RHE under the applied voltage (2 V 2V ) in the simulated PEM electrolyzer is reduced by 1 and 2 orders of magnitude, respectively, indicating that the multi-layer coating structure shown in Comparative Example 1 can achieve good corrosion protection for the titanium substrate. Example 1, which further deposits a thin layer of PtTaN coating on the outermost side based on Comparative Example 1, forms a four-layer composite coating, which continues to show excellent corrosion resistance of the multi-layer coating.

[0085] Table 1 Performance test of the prepared thin film material

[0086] Sample name E corr / V RHE ]]> I corr / μA·cm -2 ]]> I 2V / μA·cm -2 ]]> Example 1 0.158 0.0142 2.07 Comparative Example 1 0.076 0.0158 2.08 Comparative Example 2 -0.005 1.79 33.2 TA1 -0.495 288.29 147.9

[0087] Figure 4 Fig. (a) and (b) are XRD patterns of the coating and titanium plate substrate of Example 1-2 and Comparative Example 1-3 of the present application. The prepared multi-layer coating contains δ-TaN with (111) preferred orientation, which promotes the pseudo-epitaxial growth of the α-Ta layer with better corrosion resistance and conductivity, and also exists in the α-Ta intermediate layer. Figure 5 Fig. (a) and (b) are EDS energy spectra of the coating surface of Example 1 and Comparative Example 1 of the present application. There are obvious Ta and N peaks, and in Example 1, the mass percentage of Pt and Ta is about 15%, which is consistent with the composition of the reaction magnetron sputtering target material. Figure 6 Fig. (a) and (b) are XPS patterns of the coating of Example 1 and Comparative Example 1 of the present application, which further verify the presence of the Pt element, with the Pt 4fThe fine spectrum shows that Pt exists in the form of simple particles, which can reduce the interfacial contact resistance of the multilayer coating while maintaining corrosion resistance. Figure 7 The corrosion resistance and conductivity histogram of the coatings of Example 1 and Comparative Examples 1-2 of the present invention are shown in FIG. The corrosion current density of Comparative Example 2 is higher and the corrosion resistance is poor, which is related to the columnar crystal structure ( Figure 2 (c)). The TaN / Ta / TaN multilayer structure of Comparative Example 1 cuts off the columnar crystals ( Figure 2 (Figure (b)) significantly improves the overall corrosion resistance of the bipolar plate material, but the increased number of coating layers increases the interfacial contact resistance, adversely affecting the conductivity of the bipolar plate. Example 1 deposits a thin layer doped with the precious metal Pt on the surface of the TaN / Ta multilayer coating, demonstrating excellent corrosion resistance and conductivity. Figure 8 This is a physical picture of the coating and titanium plate substrate of Example 1 and Comparative Examples 1-2 of the present invention. It can be seen that the multi-layer coating is evenly covered on the surface of the metal titanium plate substrate with a size of 1 cm×1 cm, which is smooth and has no visible scratches. Figure 9 This is a scanning electron microscope image of the surface morphology of the coating and the metal titanium plate substrate of Example 1 of the present invention and Comparative Examples 1-2. The coating surface is complete, the granular grains are closely arranged, the bonding force between the coating and the titanium substrate is strong, and no coating collapse is found. Figure 10 and Figure 11 The following are the test results of surface roughness and water contact angle of the coating and metal titanium plate substrate of Example 1 and Comparative Examples 1-2 of the present invention, respectively. After the mirror-polished hydrophilic titanium plate is coated with a coating, its surface roughness is further reduced and the surface hydrophobicity is enhanced. The hydrophobic smooth surface effectively reduces the aggregation of corrosive ions on the coating surface during electrochemical corrosion, further improving the corrosion resistance of the sample. In summary, the Ta / TaN / PtTaN multilayer coating prepared by DC reactive magnetron sputtering in the present invention has a dense and smooth surface, good corrosion resistance, conductivity and hydrophobicity, and has application potential in the development of PEM bipolar plate coatings.

[0088] Example 4

[0089] A Ta / TaN / PtTaN multilayer strong corrosion-resistant coating for PEM electrolytic cell bipolar plates, the preparation process of which is as follows:

[0090] (1) grinding, mirror polishing and ultrasonic cleaning of the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0091] (2) Alternately deposit Ta and TaN layers. S1. Deposit TaN layer: The background vacuum is 6.6×10 -4Pa, argon flow rate was 20 seem, nitrogen flow rate was 2 seem, working air pressure was 0.57 Pa, sputtering power was 100 W, sputtering time was 15 min, and substrate heating temperature was 200 DEG C; S2. Depositing Ta layer: closing nitrogen valve, keeping argon flow rate as 20 seem, working air pressure as 0.57 Pa, sputtering power as 100 W, sputtering time as 15 min, and substrate heating temperature as 200 DEG C; repeating S1 step: opening nitrogen valve, adjusting nitrogen flow rate back to 2 seem, controlling working air pressure as 0.57 Pa, and keeping other parameters consistent with S1;

[0092] (3) Depositing PtTaN layer on the TaN / Ta multilayer coating. Replacing Ta target with Pt-Ta alloy target, wherein the proportion of Pt element is 10 wt.%, keeping argon flow rate as 20 seem, nitrogen flow rate as 2 seem, working air pressure as 0.57 Pa, sputtering power as 100 W, sputtering time as 15 min, and substrate heating temperature as 200 DEG C.

[0093] Example 5

[0094] A Ta / TaN / PtTaN multilayer corrosion-resistant coating for PEM electrolytic cell bipolar plate is prepared as follows:

[0095] (1) Polishing, mirror polishing and ultrasonic cleaning the titanium plate substrate, and placing the cleaned titanium substrate into a vacuum chamber;

[0096] (2) Alternately depositing Ta layer and TaN layer. S1. Depositing TaN layer: base vacuum degree was 6.6*10 -4 Pa, argon flow rate was 20 seem, nitrogen flow rate was 3 seem, working air pressure was 0.77 Pa, sputtering power was 85 W, sputtering time was 45 min, and substrate heating temperature was 350 DEG C; S2. Depositing Ta layer: closing nitrogen valve, keeping argon flow rate as 20 seem, working air pressure as 0.77 Pa, sputtering power as 85 W, sputtering time as 45 min, and substrate heating temperature as 350 DEG C; sequentially repeating S1, S2, S1, S2, S1, S2 and S1 steps;

[0097] (3) Depositing PtTaN layer on the TaN / Ta multilayer coating. Replacing Ta target with Pt-Ta alloy target, wherein the proportion of Pt element is 20 wt.%, keeping argon flow rate as 20 seem, nitrogen flow rate as 3 seem, working air pressure as 0.77 Pa, sputtering power as 85 W, sputtering time as 35 min, and substrate heating temperature as 350 DEG C.

[0098] Example 6

[0099] A Ta / TaN / PtTaN multilayer corrosion-resistant coating for a PEM electrolytic cell bipolar plate is prepared as follows:

[0100] (1) polish, mirror polish and ultrasonic clean the titanium plate substrate, and place the cleaned titanium substrate into a vacuum chamber;

[0101] (2) alternately deposit Ta layers and TaN layers, and ensure that the TaN layer is on the outermost side. S1. depositing a TaN layer: the base vacuum degree is 6.6*10 -4 Pa, the argon flow rate is 20 sccm, the nitrogen flow rate is 4 sccm, the working gas pressure is 0.6 Pa, the sputtering power is 95 W, the sputtering time is 40 min, and the substrate heating temperature is 300 DEG C; S2. depositing a Ta layer: close the nitrogen valve, keep the argon flow rate at 20 sccm, the working gas pressure at 0.6 Pa, the sputtering power at 95 W, the sputtering time at 40 min, and the substrate heating temperature at 300 DEG C; sequentially repeat the S1, S2, S1, S2 and S1 steps;

[0102] (3) depositing a PtTaN layer on the TaN / Ta multilayer coating. Replace the Ta target with a Pt-Ta alloy target, wherein the Pt element accounts for 18 wt.%, ensure that the argon flow rate is 20 sccm, the nitrogen flow rate is 4 sccm, the working gas pressure is 0.6 Pa, the sputtering power is 95 W, the sputtering time is 30 min, and the substrate heating temperature is 300 DEG C.

[0103] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates, characterized in that, The coating comprises an alternating layer, a sub-outer layer and an outermost layer which are sequentially arranged on the surface of the metal substrate in the bipolar plate of the electrolytic cell from inside to outside; The alternating layer is alternately arranged Ta layer and TaN layer, and the outer layer of the alternating layer is Ta layer; The sub-outer layer is TaN; The outermost layer is PtTaN layer.

2. A multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 1, characterized in that, The thickness of the coating is less than or equal to 3 microns.

3. A method for the production of a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates, characterized by, The method comprises the following steps: Step 1: alternately depositing Ta layer and TaN layer on the metal substrate by magnetron sputtering, and the last deposition is Ta layer; Step 2: depositing sub-outer layer on the Ta layer by magnetron sputtering, and the sub-outer layer is TaN layer; Step 3: depositing outermost layer on the sub-outer layer by magnetron sputtering, and the outermost layer is PtTaN layer.

4. A method of producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 3, characterized in that, Before step 1, the metal substrate is polished, mirror polished and ultrasonically cleaned.

5. A method of producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 3, characterized in that, The process parameters for depositing Ta layer in Step 1 are: vacuum degree 6.6x10 -4 Pa, argon flow rate 20sccm, working pressure 0.57-0.77Pa, sputtering power 80-100W, sputtering time 15-45min, and substrate heating temperature 150-350℃.

6. A method of producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 3, characterized in that, In step 1 and step 2, the process parameters for depositing TaN layer are: vacuum degree 6.6x10 -4 Pa, argon flow rate 20sccm, nitrogen flow rate 2-4sccm, working pressure 0.57-0.77Pa, sputtering power 80-100W, sputtering time 15-45min, and substrate heating temperature 150-350℃.

7. A method for producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 3, characterized in that, In step 3, the conditions for depositing PtTaN layer are as follows: direct current sputtering Pt-Ta alloy target, argon flow rate is 20 sccm, nitrogen flow rate is 2-4 sccm, working pressure is 0.57-0.77 Pa, sputtering power is 80-100 W, sputtering time is 15-35 min, and substrate heating temperature is 150-350 DEG C.

8. A method of producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 7, characterized in that, In step 3, the mass fraction of Pt element in the Pt-Ta alloy target is 10-20 wt.%.

9. A method of producing a multilayer strongly corrosion resistant coating for PEM electrolyser bipolar plates according to claim 3, characterized in that, In step 1, Ta layer and TaN layer are alternately deposited for 1-5 times.

10. A method of producing a multilayer strongly corrosion resistant coating for bipolar plates of PEM electrolytic cells according to any of claims 3-9, characterized in that, The target material for depositing Ta layer and TaN layer is Ta target.

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