A conductive corrosion-resistant solid solution MAX phase composite coating and its preparation method and application

Abstract

The present invention discloses a conductive corrosion-resistant solid solution MAX phase composite coating and its preparation method and application. The preparation method comprises: using high-power pulse magnetron sputtering technology to deposit a first Ti transition layer on the surface of a substrate; using high-power pulse magnetron sputtering combined with DC magnetron sputtering technology to deposit a first Ti‑Al‑Sn‑C layer on the surface of the first Ti transition layer, and then performing a vacuum heat treatment to form a TiC diffusion layer; using high-power pulse magnetron sputtering combined with DC magnetron sputtering technology to deposit a second Ti‑Al‑Sn‑C layer on the surface of the TiC diffusion layer, and then performing a secondary vacuum heat treatment to obtain a solid solution MAX phase composite coating. The composite coating provided by the present invention has excellent corrosion resistance, and the SnO2 passivation film formed after corrosion can stably exist in an acidic environment and has excellent electrical conductivity, thereby improving the conductive corrosion resistance of the metal substrate in harsh environments.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal surface protection, and in particular relates to a conductive corrosion-resistant solid solution MAX phase composite coating and a preparation method and application thereof. Background Art

[0002] Hydrogen fuel cells can directly and efficiently convert hydrogen into electricity. They are abundant, have a pollution-free reaction process, and have high thermal efficiency, making them considered one of the world's most promising clean energy sources. Compared to traditional low-temperature alkaline and phosphoric acid fuel cells and medium- and high-temperature solid oxide fuel cells, proton exchange membrane fuel cells (PEMFCs), as a new generation of hydrogen fuel cells, have attracted widespread attention due to their numerous advantages, including small size, light weight, high energy conversion efficiency, and low operating temperature. However, during operation, PEMFC systems experience alternating high temperatures (room temperature to 80°C) and acidic pH (approximately 2-3) during start-up and shutdown. Dissolution and corrosion of the metal bipolar plates, their core components, are inevitable. In particular, metal ions easily penetrate the proton exchange membrane, reducing ion transport efficiency. Corrosion products also significantly increase interfacial contact resistance, directly reducing the battery's output power and service life. Summary of the Invention

[0003] The main purpose of the present invention is to provide a conductive corrosion-resistant solid solution MAX phase composite coating and its preparation method and application, so as to overcome the shortcomings of the prior art.

[0004] To achieve the aforementioned object of the invention, the technical solutions adopted by the present invention include:

[0005] An embodiment of the present invention provides a method for preparing a conductive, corrosion-resistant solid solution MAX phase composite coating, which comprises:

[0006] The first Ti transition layer is deposited on the substrate surface using high-power pulsed magnetron sputtering technology;

[0007] A high-power pulsed magnetron sputtering combined with a DC magnetron sputtering technique is used, with a Ti target, an AlSn alloy target, and a C target as target materials, to deposit a first Ti-Al-Sn-C layer on the surface of the first Ti transition layer, followed by a vacuum heat treatment to form a TiC diffusion layer; wherein the phase in the TiC diffusion layer includes a TiC phase;

[0008] Furthermore, high power pulsed magnetron sputtering combined with DC magnetron sputtering technology was used, with Ti target, AlSn alloy target and C target as target materials, to deposit a second Ti-Al-Sn-C layer on the surface of the TiC diffusion layer, and then perform a secondary vacuum heat treatment to form Ti2(Al 1-x Snx )C solid solution layer, thereby obtaining a conductive and corrosion-resistant solid solution MAX phase composite coating.

[0009] The present invention also provides a conductive corrosion-resistant solid solution MAX phase composite coating prepared by the above-mentioned preparation method, wherein the composite coating comprises a Ti transition layer, a TiC diffusion layer and a Ti2 (Al 1-x Sn x )C solid solution layer.

[0010] The embodiments of the present invention also provide the use of the aforementioned conductive, corrosion-resistant solid solution MAX phase composite coating in protecting bipolar plates of hydrogen fuel cells.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] (1) In the present invention, a conductive, corrosion-resistant solid solution MAX phase composite coating with a TiC diffusion layer is used as a modified coating for a metal bipolar plate. A Ti transition layer is used to reduce the stress between the Ti-Al-Sn-C system coating and the metal substrate. The TiC diffusion layer increases the bonding force between the coating and the metal substrate, making the coating less likely to peel off during service. At the same time, the TiC phase has good stability, forming a dense anti-corrosion layer, thereby protecting the metal bipolar plate from corrosion in a PEMFCs environment.

[0013] (2) The present invention prepares a conductive corrosion-resistant solid solution MAX phase composite coating on the surface of the metal substrate. The coating can generate a uniform and dense SnO2 passivation film under service conditions. At the same time, the generated titanium, aluminum and other oxides have good corrosion resistance and high chemical stability, prevent erosion by external corrosive substances, inhibit the dissolution of metal ions, and are beneficial to improving the corrosion resistance of the coating. In addition, SnO2, as an n-type semiconductor, is an excellent conductive material (conductivity is 5.952Ω -1 cm -1 ), which is beneficial to the conductive properties of the coating;

[0014] (3) The conductive corrosion-resistant solid solution MAX phase composite coating of the present invention has a high hardness. The introduction of the TiC diffusion layer increases the hardness of the coating, making it resistant to external scratches and wear, thereby extending the service life of the coating;

[0015] (4) The present invention obtains a conductive corrosion-resistant solid solution MAX phase composite coating by secondary sputtering and secondary vacuum heat treatment, with a Ti transition layer, a TiC diffusion layer, a Ti2(Al 1-x Sn x ) The C layer has a gradient structure. This gradient structure increases the bonding strength of the coating and can reduce the residual stress caused by uneven deposition rate or temperature changes during the deposition process, further improving the stability of the coating;

[0016] (5) The gradient structure of the conductive corrosion-resistant solid solution MAX phase composite coating in the present invention can increase the bonding strength of the coating, improve its mechanical strength, help enhance the shear and tensile resistance of the coating, and reduce the risk of cracking and peeling of the coating during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 The Ti2(Al 0.96 Sn 0.04 ) Schematic diagram of the gradient change of C solid solution MAX phase composite coating;

[0019] Figure 2 The Ti2(Al 0.96 Sn 0.04 ) SEM image of C solid solution MAX phase composite coating;

[0020] Figure 3 The Ti2(Al 0.96 Sn 0.04 ) Chemical composition spectrum of C solid solution MAX phase composite coating;

[0021] Figure 4 The Ti2(Al 0.96 Sn 0.04 ) XRD spectrum of C solid solution MAX phase composite coating;

[0022] Figure 5 The Ti2(Al 0.96 Sn 0.04 ) SEM image of C solid solution MAX phase composite coating;

[0023] Figure 6 The Ti2(Al 1-x Sn x ) Potentiodynamic polarization curves of C (x = 0.02, 0.04, 0.06) solid solution MAX phase composite coating;

[0024] Figure 7 Ti2(Al 0.96 Sn0.04 ) Interface contact resistance variation diagram of C solid solution MAX phase composite coating;

[0025] Figure 8 The Ti2(Al 0.96 Sn 0.04 )Scanning electron microscope image of C solid solution MAX phase composite coating. DETAILED DESCRIPTION

[0026] In view of the shortcomings of the prior art, the inventors of this case, after long-term research and extensive practice, have proposed the technical solution of the present invention. The technical solution of the present invention will be clearly and completely described below. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making any creative effort shall fall within the scope of protection of the present invention.

[0027] Specifically, as one aspect of the technical solution of the present invention, a method for preparing a conductive, corrosion-resistant solid solution MAX phase composite coating includes:

[0028] The first Ti transition layer is deposited on the substrate surface using high-power pulsed magnetron sputtering technology;

[0029] A high-power pulsed magnetron sputtering combined with a DC magnetron sputtering technique is used, with a Ti target, an AlSn alloy target, and a C target as target materials, to deposit a first Ti-Al-Sn-C layer on the surface of the first Ti transition layer, followed by a vacuum heat treatment to form a TiC diffusion layer; wherein the phase in the TiC diffusion layer includes a TiC phase;

[0030] Furthermore, high power pulsed magnetron sputtering combined with DC magnetron sputtering technology was used, with Ti target, AlSn alloy target and C target as target materials, to deposit a second Ti-Al-Sn-C layer on the surface of the TiC diffusion layer, and then perform a secondary vacuum heat treatment to form Ti2(Al 1-x Sn x )C solid solution layer, thereby obtaining a conductive and corrosion-resistant solid solution MAX phase composite coating.

[0031] The TIC diffusion layer in the present invention forms a gradient structure, with a lower TiC content near the substrate area and then gradually transitioning to the outer layer, gradually increasing. The formed TiC grains are distributed in the solid solution. Due to the existence of the gradient structure, a good transition layer is formed between the TiC coating and the substrate, avoiding a direct interface between the coating and the substrate, and greatly improving the bonding strength between the two. Secondly, the first heat treatment causes the components of the first Ti-Al-Sn-C layer to diffuse with the Ti transition layer, forming a diffusion layer TiC and part of the MAX phase (Ti(Al, Sn)C) nucleus. Since the coating grains grow after the heat treatment, defects such as holes are prone to occur. Therefore, the sample will undergo a secondary sputtering coating and a secondary heat treatment to increase the coating thickness and fill the film defects caused by the first high-temperature heat treatment. After the first heat treatment, there may still be a part of elements such as Al and Sn in the Ti-Al-Sn-C layer that have not fully participated in the reaction. These residual elements further react and diffuse with the second deposited Ti-Al-Sn-C layer. As elements like C, Al, and Sn diffuse, a gradual gradient structure forms from the substrate to the surface. This gradient structure helps improve the coating's interfacial bonding strength and other properties.

[0032] In some preferred embodiments, the preparation method specifically includes: using high-power pulse magnetron sputtering technology, placing a substrate in a vacuum reaction chamber, using a Ti target as a target material, and using an inert gas as a working gas to deposit a first Ti transition layer on the surface of the substrate; wherein, the substrate bias voltage is -50 to 200 V, the high-power pulse duty cycle is 1 to 10%, the high-power pulse frequency is 200 to 1000 Hz, the pulse width is 50 to 200 μs, the Ti target is a high-power pulse magnetron sputtering target material, the average sputtering power of the Ti target is 80 to 150 W, the gas pressure of the reaction chamber is 0.5-2.0 Pa, the target distance between the substrate and the Ti target is 8 to 14 cm, the deposition temperature is 100 to 300° C., and the deposition time is 0.5 to 1.0 h.

[0033] Furthermore, the inert gas includes argon, but is not limited thereto.

[0034] Furthermore, the thickness of the first Ti transition layer is 0.1-0.2 μm.

[0035] Furthermore, the material of the substrate includes any one or a combination of two or more of titanium alloy, titanium, aluminum, aluminum alloy, and stainless steel.

[0036] In some preferred embodiments, the preparation method specifically comprises:

[0037] High-power pulsed magnetron sputtering combined with DC magnetron sputtering technology is used, with Ti target, AlSn alloy target, and C target as target materials, and inert gas as working gas, to deposit a first Ti-Al-Sn-C layer on the surface of the first Ti transition layer; wherein the atomic ratio of Al to Sn in the AlSn alloy target is 99:1 to 70:30, the substrate bias voltage is -100 to 200 V, the high-power pulse duty cycle is 1 to 10%, the high-power pulse frequency is 200 to 1000 Hz, and the pulse The width is 50-200 μs, the Ti target is a high-power pulsed magnetron sputtering target, and the average sputtering power of the Ti target is 80-100 W; the AlSn alloy target and the C target are DC magnetron sputtering targets, the DC sputtering power of the AlSn alloy target is 40-70 W, and the DC sputtering power of the C target is 40-100 W, the gas pressure of the reaction chamber is 0.5-2.0 Pa, the deposition temperature is 100-300 ° C, the deposition time is 0.5-1.0 h, and the distance between the substrate and the target is 8-15 cm;

[0038] And, at a vacuum degree of 3×10 -4 In a reaction chamber below Pa, the temperature of the chamber is raised to 350-550° C., and a vacuum heat treatment is performed on the substrate on which the first Ti transition layer and the first Ti-Al-Sn-C layer are deposited for 1.0-1.5 hours to form a TiC diffusion layer.

[0039] Furthermore, the substrate bias voltage is -90 to -150V.

[0040] Furthermore, the thickness of the first Ti—Al—Sn—C layer is 0.1 to 0.3 μm.

[0041] Furthermore, the thickness of the TiC diffusion layer is 0.1-0.2 μm.

[0042] Furthermore, during a vacuum heat treatment, Ti and C elements in the first Ti transition layer and the first Ti-Al-Sn-C layer diffuse into each other, eventually forming a TiC diffusion layer. The thickness of the finally formed Ti transition layer will vary slightly compared with that of the first Ti transition layer, but the variation is not large and can be ignored.

[0043] In some preferred embodiments, the preparation method specifically comprises:

[0044] High-power pulsed magnetron sputtering combined with DC magnetron sputtering technology is used, with Ti target, AlSn alloy target and C target as target materials, and inert gas as working gas, to deposit a second Ti-Al-Sn-C layer on the surface of the TiC diffusion layer; wherein the atomic ratio of Al to Sn in the AlSn alloy target is 99:1 to 70:30, the substrate bias voltage is -100 to 200V, the high-power pulse duty cycle is 1 to 10%, the high-power pulse frequency is 200 to 1000Hz, and the pulse width is 0. The sputtering time is 50-200 μs, the Ti target is a high-power pulsed magnetron sputtering target, and the average sputtering power of the Ti target is 80-100 W; the AlSn alloy target and the C target are DC magnetron sputtering targets, the DC sputtering power of the AlSn alloy target is 40-70 W, and the DC sputtering power of the C target is 40-100 W, the gas pressure of the reaction chamber is 0.5-2.0 Pa, the deposition temperature is 100-3000 ° C, the deposition time is 4.0-8.0 h, and the distance between the substrate and the target is 8-15 cm;

[0045] And, the substrate on which the second Ti-Al-Sn-C layer was deposited was placed in a vacuum of 3×10 -4 Pa below the heat treatment device, and the temperature is raised to 700 ~ 8000 ℃ at a heating rate of 10 ~ 50 ℃ / min for secondary vacuum heat treatment for 1.0 ~ 3h, thereby forming Ti2 (Al 1-x Sn x )C solid solution layer; wherein, wherein 0<x<1.

[0046] Furthermore, the substrate bias voltage is -90 to -120V.

[0047] Furthermore, the thickness of the second Ti—Al—Sn—C layer is 1.0 to 3.0 μm.

[0048] Furthermore, the Ti2(Al 1-x Sn x )The thickness of the C solid solution layer is 1.1 to 3.2 μm.

[0049] The present invention adopts high-power pulsed magnetron sputtering combined with DC magnetron sputtering technology, and combines the deposition process of secondary sputtering and secondary heat treatment to prepare the composite coating. The high-power pulse realizes the controllable adjustment of high plasma density and high ionization rate through the advantages of high peak power and low duty cycle, which is conducive to the preparation of high-purity and dense MAX phase coating; at the same time, through the secondary sputtering and secondary heat treatment, the defects such as holes on the coating surface are filled by ion bombardment, and the residual stress between the coatings is reduced, thereby obtaining a higher quality coating.

[0050] Another aspect of the present invention provides a conductive corrosion-resistant solid solution MAX phase composite coating prepared by the above-mentioned preparation method, wherein the composite coating comprises a Ti transition layer, a TiC diffusion layer and a Ti2 (Al 1-x Sn x )C solid solution layer.

[0051] Specifically, the composite coating comprises a Ti transition layer, a TiC diffusion layer without columnar growth defects and a dense Ti2(Al 1-x Sn x )C solid solution layer.

[0052] Furthermore, the total thickness of the conductive corrosion-resistant solid solution MAX phase composite coating is 1.2 to 3.5 μm.

[0053] The composite coating provided by the present invention has excellent corrosion resistance, and the SnO2 passivation film formed by the composite coating after corrosion can exist stably in an acidic environment and has excellent electrical conductivity, thereby improving the electrical conductivity and corrosion resistance of the metal substrate in harsh environments.

[0054] Another aspect of the embodiments of the present invention further provides the use of the aforementioned conductive, corrosion-resistant solid solution MAX phase composite coating in protecting bipolar plates of hydrogen fuel cells.

[0055] Another aspect of the embodiments of the present invention further provides a proton exchange membrane fuel cell bipolar plate, the surface of which is provided with the aforementioned conductive corrosion-resistant solid solution MAX phase composite coating.

[0056] Another aspect of an embodiment of the present invention further provides a surface modification method for a metal substrate, comprising: preparing a conductive, corrosion-resistant solid solution MAX phase composite coating on the surface of the metal substrate using the aforementioned method.

[0057] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0058] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0059] Example 1:

[0060] like Figure 1 As shown in the figure, in this embodiment, the substrate is 316L stainless steel for proton exchange membrane fuel cells, and the power supply used is a high-power pulse magnetron sputtering power supply and a DC magnetron sputtering power supply. At the same time, the secondary sputtering and secondary heat treatment technology are combined to form a Ti2 (Al0.91 Sn 0.09 ) The preparation method of C solid solution MAX phase composite coating is as follows:

[0061] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol for 10 minutes in sequence, and then dried after cleaning.

[0062] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0063] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0064] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 2.5 Pa. The substrate was etched using ionized argon ions for 30 min at a temperature of 2000°C.

[0065] E. Pre-sputtering: The argon flow rate was 180 sccm, and the pressure was 0.8 Pa. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (90:10 at.%) alloy target and the C target, and the pre-sputtering was performed on the AlSn (90:10 at.%) alloy target and the C target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0066] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, deposition time 30 min, deposition temperature 2000°C;

[0067] G. Sputtering of Ti-Al-Sn-C layer: gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (90:10 at.%) alloy target DC power supply 60 W, C target DC power supply 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 1 h, deposition temperature 2000°C;

[0068] H. Heat treatment: in vacuum degree 3.0×10 -4 Pa, the samples deposited with Ti transition layer and Ti-Al-Sn-C layer were heat treated by raising the cavity temperature to 5000℃ and holding the temperature for 60min, thereby forming a TiC diffusion layer on the substrate surface.

[0069] I. Sputtering of Ti-Al-Sn-C layer: gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (90:10 at.%) alloy target DC power supply power 60 W, C target DC power supply sputtering power 45 W, target distance between substrate and Ti target 12 cm, target distance between substrate and AlSn (90:10 at.%) alloy target 10 cm, target distance between substrate and C target 12 cm, deposition time 8 h, deposition temperature 2000°C;

[0070] J. Annealing: at a vacuum degree of 3.0×10 -4 Pa below, the samples deposited with TiC diffusion layer and Ti-Al-Sn-C layer were heat treated at a heating rate of 10 ° C / min, annealing temperature of 750 ° C, and holding time of 90 min, thereby forming Ti2 (Al 0.96 Sn 0.04 )C solid solution MAX phase composite coating.

[0071] Figure 1 The Ti2(Al2O3) prepared in this example was obtained after secondary sputtering and secondary heat treatment. 0.91 Sn 0.09 ) Schematic diagram of the gradient structure change of C solid solution MAX phase composite coating;

[0072] Figure 2 Ti2(Al 0.91 Sn 0.09 ) Scanning electron microscope image of C solid solution MAX phase composite coating, it can be seen that the MAX phase coating is uniform and dense after annealing;

[0073] Figure 3 The Ti2(Al 0.91 Sn 0.09 ) Chemical composition spectrum of C solid solution MAX phase composite coating, it can be seen that the Ti-Al-Sn-C layer was successfully prepared by high-power pulsed magnetron sputtering combined with DC magnetron sputtering technology, secondary sputtering and secondary heat treatment technology;

[0074] Figure 4 Ti2(Al 0.91 Sn 0.09)C solid solution MAX phase composite coating XRD spectrum, it can be seen that the use of high power pulsed magnetron sputtering combined with DC magnetron sputtering technology combined with secondary sputtering and secondary heat treatment technology to successfully prepare Ti2(Al 0.96 Sn 0.04 )C solid solution MAX phase.

[0075] Comparative Example 1:

[0076] This comparative example is a comparative example of the above-mentioned embodiment 1.

[0077] In this comparative example, a high-power pulsed magnetron sputtering power supply and a DC magnetron sputtering power supply were used, and a one-time sputtering and one-time heat treatment technology was used. Other conditions were exactly the same as those in the above-mentioned Example 1. 0.91 Sn 0.09 )C solid solution MAX phase, the specific process is as follows:

[0078] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol for 10 minutes in sequence, and then dried after cleaning.

[0079] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0080] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0081] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 2.5 Pa. The substrate was etched using ionized argon ions for 30 min at a temperature of 200°C.

[0082] E. Pre-sputtering: With an argon flow rate of 180 sccm and a pressure of 0.8 Pa, a DC power supply was connected to the Ti target, AlSn (90:10 at.%) alloy target, and C target. Pre-sputtering was performed on the Ti target, AlSn (90:10 at.%) alloy target, and C target to remove surface oxides or adsorbed impurities. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0083] F. Sputtering Ti transition layer: Ar flow rate is 180 sccm, gas pressure is 0.8 Pa, bias voltage is -120 V, sputtering power of Ti target high power pulse power supply is 100 W, target distance between substrate and Ti target is 12 cm, deposition time is 30 min, deposition temperature is 200 °C;

[0084] G. Sputtering Ti-Al-Sn-C layer: gas pressure 0.8 Pa, bias voltage -120 V, Ti target high-power pulse power supply sputtering power of 100 W, AlSn (90:10 at.%) alloy target DC power supply power of 60 W, C target DC power supply sputtering power of 45 W, target spacing between substrate and Ti target of 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target of 10 cm, target spacing between substrate and C target of 12 cm, deposition time of 8 h, deposition temperature of 200°C;

[0085] H. Annealing: at a vacuum degree of 3.0×10 -4 Pa, the samples deposited with Ti transition layer and Ti-Al-Sn-C layer were heat treated with a heating rate of 10℃ / min, annealing temperature of 750℃ and holding time of 90min, thereby forming a MAX phase composite coating on the substrate surface.

[0086] Figure 5 The scanning electron microscope image of the MAX phase composite coating prepared in this comparative example shows that there is a serious cracking and peeling phenomenon on the surface of the coating, and the coating quality is poor. It can be seen that the Ti2(Al 0.91 Sn 0.09 )C solid solution MAX phase composite coating and substrate have good coating quality.

[0087] Example 2:

[0088] In this embodiment, AlSn (80:20 at.%) alloy target was used, and the other conditions were exactly the same as those in the above embodiment 1. 0.83 Sn 0.17 )C solid solution MAX phase coating, the specific process is as follows:

[0089] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol for 10 minutes in sequence, and then dried after cleaning.

[0090] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0091] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0092] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 20 mTorr. The substrate was etched using ionized argon ions for 30 minutes at a temperature of 200°C.

[0093] E. Pre-sputtering: An argon flow rate of 180 sccm and a pressure of 6 mTorr were applied to the Ti target. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (80:20 at.%) alloy target and the C target. Pre-sputtering was performed on the AlSn (80:20 at.%) alloy target and the C target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0094] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, deposition time 30 min, deposition temperature 200°C;

[0095] G. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (80:20 at.%) alloy target DC power supply 60 W, C target DC power supply 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (80:20 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 1 h, deposition temperature 200°C;

[0096] H. Heat treatment: in vacuum degree 3.0×10 -4 Pa, the samples deposited with Ti transition layer and Ti-Al-Sn-C layer were heat treated by raising the cavity temperature to 500 ° C and holding the temperature for 60 min to form a TiC diffusion layer on the substrate surface.

[0097] I. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (80:20 at.%) alloy target DC power supply 60 W, C target DC power supply 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (80:20 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 8 h, deposition temperature 200°C;

[0098] J. Annealing: at a vacuum degree of 3.0×10-4 Pa below, the samples deposited with TiC diffusion layer and Ti-Al-Sn-C layer were heat treated at a heating rate of 10 ° C / min, annealing temperature of 750 ° C, and holding time of 90 min, thereby forming Ti2 (Al 0.83 Sn 0.17 )C solid solution MAX phase composite coating.

[0099] Example 3:

[0100] In this embodiment, AlSn (95:5 at.%) alloy target was used, and the other conditions were exactly the same as those in the above embodiment 1. 0.94 Sn 0.06 )C solid solution MAX phase coating, the specific process is as follows:

[0101] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol in sequence for 10 minutes, and then dried after cleaning.

[0102] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0103] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0104] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 20 mTorr. The substrate was etched using ionized argon ions for 30 minutes at a temperature of 200°C.

[0105] E. Pre-sputtering: The argon flow rate was 180 sccm and the pressure was 6 mTorr. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (95:5 at.%) alloy target and the C target. The AlSn (95:5 at.%) alloy target and the C target were pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0106] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, substrate-Ti target distance 12 cm, deposition time 30 min, deposition temperature 200°C;

[0107] G. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, discharge voltage 700 V, peak current 2 A, pulse frequency 500 Hz, duty cycle 5%, AlSn (95:5 at.%) alloy target DC power supply power 60 W, C target DC power supply sputtering power 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (95:5 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 1 h, deposition temperature 200°C;

[0108] H. Heat treatment: in vacuum degree 3.0×10 -4 Pa, the samples deposited with Ti transition layer and Ti-Al-Sn-C layer were heat treated by raising the cavity temperature to 500 ° C and holding the temperature for 60 min to form a TiC diffusion layer on the substrate surface.

[0109] I. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, discharge voltage 700 V, peak current 2 A, pulse frequency 500 Hz, duty cycle 5%, AlSn (95:5 at.%) alloy target DC power supply power 60 W, C target DC power supply sputtering power 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (95:5 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 8 h, deposition temperature 200°C;

[0110] J. Annealing: at a vacuum degree of 3.0×10 -4 Pa below, the samples deposited with TiC diffusion layer and Ti-Al-Sn-C layer were heat treated at a heating rate of 10 ° C / min, annealing temperature of 750 ° C, and holding time of 90 min, thereby forming Ti2 (Al 0.94 Sn 0.06 )C solid solution MAX phase composite coating.

[0111] Corrosion resistance and electrical conductivity test:

[0112] The Ti2(Al 1-x Sn x )C solid solution MAX phase composite coating substrate corrosion resistance test, the solution is 0.5M H2SO4 + 5ppmHF solution, the solution temperature is 80℃, Figure 6The test results show that the Ti2(Al 1-x Sn x )C solid solution MAX phase composite coatings all have stable corrosion resistance, among which the corrosion current density of Example 1 is as low as 4.29×10 -7 A.cm -2 .

[0113] Comparative Example 2:

[0114] In this comparative example, the substrate is 316L stainless steel for proton exchange membrane fuel cells, and the power sources used are high-power pulsed magnetron sputtering power supply and DC magnetron sputtering power supply. Combined with secondary sputtering technology and primary heat treatment, the Ti-Al-Sn-C layer on the substrate surface is prepared as follows:

[0115] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol for 10 minutes in sequence, and then dried after cleaning.

[0116] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0117] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0118] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 2.5 Pa. The substrate was etched using ionized argon ions for 30 min at a temperature of 200°C.

[0119] E. Pre-sputtering: An argon flow rate of 180 sccm and a pressure of 6 mTorr were applied to the Ti target. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (90:10 at.%) alloy target and the C target. Pre-sputtering was performed on the AlSn (90:10 at.%) alloy target and the C target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0120] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, C target DC power supply sputtering power 45 W, target distance between substrate and C target 12 cm, deposition time 30 min, deposition temperature 200°C;

[0121] G. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (90:10 at.%) alloy target DC power supply 60 W, C target DC power supply 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 1 h, deposition temperature 200°C;

[0122] H. Heat treatment: in vacuum degree 3.0×10 -4 Pa, the samples of deposited Ti layer and Ti-Al-Sn-C layer were heat treated by raising the cavity temperature to 500℃ and holding the temperature for 60min, thereby forming a TiC diffusion layer on the surface of the substrate.

[0123] I. Sputtering of Ti-Al-Sn-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power of 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (90:10 at.%) alloy target DC power of 60 W, C target DC power of 45 W, target spacing between substrate and Ti target of 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target of 10 cm, target spacing between substrate and C target of 12 cm, deposition time 8 h, deposition temperature 2000°C;

[0124] The corrosion resistance of the Ti-Al-Sn-C layer obtained in Comparative Example 2 was tested using a three-electrode electrochemical test system. The solution was 0.5 M H2SO4 + 5 ppm HF solution at a temperature of 80 ° C. The corrosion current density was 3.16 × 10 -4 A.cm 2 Because the coating did not undergo a second annealing treatment, a large amount of pure metal Ti and Al existed in the coating in the form of unalloyed metals. Pure metal Ti and Al have high electrochemical activity and are easily corroded by corrosive media, resulting in the coating's corrosion resistance being lower than that of the implementation case.

[0125] Comparative Example 3:

[0126] In this comparative example, the substrate is 316L stainless steel for proton exchange membrane fuel cells, and the power sources used are high-power pulsed magnetron sputtering power supply and DC magnetron sputtering power supply. Combined with secondary sputtering and secondary heat treatment technology, the Ti2AlCMAX phase coating on the substrate surface is prepared as follows:

[0127] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol in sequence for 10 minutes, and then dried after cleaning.

[0128] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0129] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 2000℃.

[0130] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 20 mTorr. The substrate was etched using ionized argon ions for 30 minutes at a temperature of 200°C.

[0131] E. Pre-sputtering: With an argon flow rate of 180 sccm and a pressure of 6 mTorr, a HiPIMS power supply was connected to the Ti target, and pre-sputtering was performed on the Ti target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the Al alloy target and the C target, and pre-sputtering was performed on the Al and C targets to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 minutes, and the temperature was 2000°C.

[0132] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, deposition time 30 min, deposition temperature 200°C;

[0133] G. Sputtering of Ti-Al-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power 100 W, pulse frequency 500 Hz, duty cycle 5%, Al target DC power 50 W, C target DC power 45 W, target distance between substrate and Ti target 12 cm, target distance between substrate and Al alloy target 10 cm, target distance between substrate and C target 12 cm, deposition time 1 h, deposition temperature 2000°C;

[0134] H. Heat treatment: in vacuum degree 3.0×10 -4 Pa, the samples deposited with Ti transition layer and Ti-Al-C layer were heat treated by raising the cavity temperature to 5000℃ and holding the temperature for 60min, thereby forming a TiC diffusion layer on the substrate surface.

[0135] I. Sputtering of Ti-Al-C layer: gas pressure 6 mTorr, bias voltage -120 V, Ti target HiPIMS power 100 W, pulse frequency 500 Hz, duty cycle 5%, Al target DC power 50 W, C target DC power 45 W, target distance between substrate and Ti target 12 cm, target distance between substrate and Al alloy target 10 cm, target distance between substrate and C target 12 cm, deposition time 8 h, deposition temperature 2000°C;

[0136] J. Annealing: at a vacuum degree of 3.0×10 -4 Pa, the samples deposited with TiC diffusion layer and Ti-Al-C layer were heat treated with a heating rate of 10℃ / min, annealing temperature of 750℃ and holding time of 90min, thereby forming a Ti2AlCMAX phase coating on the substrate surface.

[0137] The corrosion resistance of the substrate with the Ti2AlC MAX phase coating on the surface obtained in the above comparative example was tested using a three-electrode electrochemical test system. The solution was 0.5M H2SO4+5ppm HF solution at a temperature of 80°C. The results showed that the corrosion progressed further due to the lack of SnO2 passivation film after corrosion. The corrosion current density was 1.21×10 -5 Acm -2 , the corrosion resistance is far worse than that of the implementation case.

[0138] Figure 7 The Ti2(Al 0.91 Sn 0.09 )C solid solution MAX phase composite coating interface contact resistance change diagram, compared with the comparative example 3, Example 1 forms a SnO2 passivation film with better conductive properties after corrosion, so that the interface contact resistance of the coating can still be maintained at a low level.

[0139] Comparative Example 4 (lack of one vacuum heat treatment)

[0140] In this comparative example, the substrate is 316L stainless steel for proton exchange membrane fuel cells, and the power sources used are high-power pulsed magnetron sputtering power supply and DC magnetron sputtering power supply. Combined with secondary sputtering and primary heat treatment technology, the Ti2AlCMAX phase composite coating on the substrate surface is prepared as follows:

[0141] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol in sequence for 10 minutes, and then dried after cleaning.

[0142] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0143] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 2000℃.

[0144] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 2.5 Pa. The substrate was etched using ionized argon ions for 30 min at a temperature of 2000°C.

[0145] E. Pre-sputtering: The argon flow rate was 180 sccm, and the pressure was 0.8 Pa. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (90:10 at.%) alloy target and the C target, and the pre-sputtering was performed on the AlSn (90:10 at.%) alloy target and the C target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 2000°C.

[0146] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, deposition time 30 min, deposition temperature 2000°C;

[0147] G. Sputtering of Ti-Al-Sn-C layer: gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply 100 W, pulse frequency 500 Hz, duty cycle 5%, AlSn (90:10 at.%) alloy target DC power supply 60 W, C target DC power supply 45 W, target spacing between substrate and Ti target 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target 10 cm, target spacing between substrate and C target 12 cm, deposition time 1 h, deposition temperature 2000°C;

[0148] H. Sputtering of Ti-Al-Sn-C layer: gas pressure of 0.8 Pa, bias voltage of -120 V, Ti target HiPIMS power of 100 W, pulse frequency of 500 Hz, duty cycle of 5%, AlSn (90:10 at.%) alloy target DC power of 60 W, C target DC power of 45 W, target spacing between substrate and Ti target of 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target of 10 cm, target spacing between substrate and C target of 12 cm, deposition time of 8 h, deposition temperature of 2000°C;

[0149] I. Annealing: at a vacuum degree of 3.0×10 -4 Pa, the sample was heat treated at a heating rate of 100 ° C / min, annealing temperature of 750 ° C, and holding time of 90 min, thereby forming Ti2 (Al 0.91 Sn 0.09 )C solid solution MAX phase composite coating.

[0150] Figure 8 Ti2(Al 0.91 Sn 0.09 A scanning electron microscope image of a C solid solution MAX phase composite coating shows significant, large-scale flaking after corrosion. This flaking indicates insufficient adhesion and inability to resist the erosion of the corrosive medium. The corrosive medium directly contacts the substrate surface, accelerating damage to the substrate.

[0151] Comparative Example 5 (TiC diffusion layer replaced by direct preparation using TiC target)

[0152] In this embodiment, the substrate is 316L stainless steel for proton exchange membrane fuel cells, and the power sources used are high-power pulse magnetron sputtering power supply and DC magnetron sputtering power supply. At the same time, the secondary sputtering and secondary heat treatment technology are combined to form a Ti2 (Al 0.91 Sn 0.09 ) The preparation method of C solid solution MAX phase composite coating is as follows:

[0153] A. Substrate pretreatment: The polished metal substrate surface is ultrasonically cleaned with acetone and alcohol for 10 minutes in sequence, and then dried after cleaning.

[0154] B. Sample installation: Fix the processed substrate on the sample stage of the magnetron sputtering equipment.

[0155] C. Cavity vacuum preparation: Pump the vacuum of the cavity to 4.0×10 -3 Pa below, and the temperature is heated to 200°C.

[0156] D. Etching the substrate: Argon gas was introduced into the vacuum chamber at a flow rate of 200 sccm, a bias voltage of -600 V, and a pressure of 2.5 Pa. The substrate was etched using ionized argon ions for 30 min at a temperature of 200°C.

[0157] E. Pre-sputtering: The argon flow rate was 180 sccm, and the pressure was 0.8 Pa. A HiPIMS power supply was connected to the Ti target, and the Ti target was pre-sputtered to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 150 W, the pulse frequency was 500 Hz, and the duty cycle was 5%. A DC power supply was connected to the AlSn (90:10 at.%) alloy target and the C target, and the pre-sputtering was performed on the AlSn (90:10 at.%) alloy target and the C target to remove oxides or adsorbed impurities on the target surface. The pre-sputtering power was 100 W, the sputtering time was 10 min, and the temperature was 200°C.

[0158] F. Sputtering of Ti transition layer: Ar flow rate 180 sccm, gas pressure 0.8 Pa, bias voltage -120 V, Ti target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and Ti target 12 cm, deposition time 30 min, deposition temperature 200°C;

[0159] G. Sputtering TiC layer: gas pressure 0.8 Pa, bias voltage -120 V, TiC target HiPIMS power supply sputtering power 100 W, pulse frequency 500 Hz, duty cycle 5%, target distance between substrate and TiC target 12 cm, deposition time 1 h, deposition temperature 200 °C;

[0160] H. Sputtering of Ti-Al-Sn-C layer: gas pressure of 0.8 Pa, bias voltage of -120 V, Ti target HiPIMS power of 100 W, pulse frequency of 500 Hz, duty cycle of 5%, AlSn (90:10 at.%) alloy target DC power of 60 W, C target DC power of 45 W, target spacing between substrate and Ti target of 12 cm, target spacing between substrate and AlSn (90:10 at.%) alloy target of 10 cm, target spacing between substrate and C target of 12 cm, deposition time of 8 h, deposition temperature of 200°C;

[0161] J. Annealing: at a vacuum degree of 3.0×10 -4 Pa below, the samples of deposited TiC layer and Ti-Al-Sn-C layer were heat treated at a heating rate of 10℃ / min, annealing temperature of 750℃, and holding time of 90min, thereby forming Ti2(Al 0.91 Sn 0.09 )C solid solution MAX phase composite coating.

[0162] Compared to the TiC layer formed by diffusion during heat treatment, the TiC layer deposited directly from a TiC target in this comparative example typically exhibits a looser, clustered distribution, with larger and more unevenly distributed particles. Furthermore, the deposition process is prone to defects such as residual stress and voids, which can lead to interlayer cracking. In contrast, the TiC layer formed by diffusion between Ti and C atoms during heat treatment is uniform, dense, and has fewer microscopic defects. It also exhibits better interfacial bonding with the substrate and lowers residual stress.

[0163] The Ti2(Al 0.91 Sn 0.09 The corrosion resistance of the substrate of the C solid solution MAX phase composite coating was tested in a 0.5M H2SO4 + 5ppm HF solution at 80°C. The results showed that the lack of a diffusion layer easily led to stress concentration, resulting in cracking of the coating. Therefore, the corrosive medium can directly penetrate the substrate through the cracks, further accelerating the development of corrosion. The corrosion current density was 8.17×10 -6 Acm -2 , the corrosion resistance is far worse than that of the implementation case.

[0164] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments using other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0165] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical variations made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the scope of protection of the present invention.

Claims

1. A method for preparing a conductive, corrosion-resistant solid solution MAX phase composite coating, characterized in that: include: The first Ti transition layer is deposited on the substrate surface using high-power pulsed magnetron sputtering technology; A first Ti-Al-Sn-C layer is deposited on the surface of the first Ti transition layer using a high-power pulsed magnetron sputtering combined with a DC magnetron sputtering technique, with a Ti target, an AlSn alloy target, and a C target as target materials. The temperature of the chamber is then raised to 350-550° C., and the substrate on which the first Ti transition layer and the first Ti-Al-Sn-C layer are deposited is subjected to a vacuum heat treatment for 1.0-1.5 hours, thereby forming a TiC diffusion layer; wherein the phase in the TiC diffusion layer includes a TiC phase; Furthermore, a high-power pulsed magnetron sputtering combined with a DC magnetron sputtering technology was used, with Ti target, AlSn alloy target, and C target as target materials, to deposit a second Ti-Al-Sn-C layer on the surface of the TiC diffusion layer, and then the temperature was raised to 700-800°C at a heating rate of 10-50°C / min for a secondary vacuum heat treatment of 1.0-3h to form Ti2(Al 1-x Sn x )C solid solution layer, thereby obtaining a conductive and corrosion-resistant solid solution MAX phase composite coating.

2. The preparation method according to claim 1, characterized in that Specifically include: High-power pulsed magnetron sputtering technology is adopted, a substrate is placed in a vacuum reaction chamber, a Ti target is used as the target material, and an inert gas is used as the working gas to deposit and form a first Ti transition layer on the surface of the substrate; wherein, the substrate bias voltage is -50~200V, the high-power pulse duty cycle is 1~10%, the high-power pulse frequency is 200~1000Hz, the pulse width is 50~200μs, the Ti target is a high-power pulsed magnetron sputtering target material, the average sputtering power of the Ti target is 80~150W, the gas pressure of the reaction chamber is 0.5-2.0Pa, the target distance between the substrate and the Ti target is 8~14cm, the deposition temperature is 100~300℃, and the deposition time is 0.5~1.0h.

3. The preparation method according to claim 2, wherein: The thickness of the first Ti transition layer is 0.1-0.2 μm; and / or the material of the substrate includes any one or a combination of two or more of titanium alloy, titanium, aluminum, aluminum alloy, and stainless steel.

4. The preparation method according to claim 1, characterized in that Specifically include: High-power pulsed magnetron sputtering combined with DC magnetron sputtering technology is used, with Ti target, AlSn alloy target, and C target as target materials, and inert gas as working gas, to deposit a first Ti-Al-Sn-C layer on the surface of the first Ti transition layer; wherein the atomic ratio of Al to Sn in the AlSn alloy target is 99:1-70:30, the substrate bias voltage is -100-200 V, the high-power pulse duty cycle is 1-10%, the high-power pulse frequency is 200-1000 Hz, and the pulse The width is 50~200μs, the Ti target is a high-power pulsed magnetron sputtering target, and the average sputtering power of the Ti target is 80~100W; the AlSn alloy target and the C target are DC magnetron sputtering targets, the DC sputtering power of the AlSn alloy target is 40~70W, and the DC sputtering power of the C target is 40~100W, the gas pressure of the reaction chamber is 0.5-2.0Pa, the deposition temperature is 100~300℃, the deposition time is 0.5~1.0h, and the distance between the substrate and the target is 8~15cm; And, at a vacuum degree of 3×10 -4 The substrate on which the first Ti transition layer and the first Ti-Al-Sn-C layer are deposited is subjected to a vacuum heat treatment in a reaction chamber below Pa to form a TiC diffusion layer.

5. The preparation method according to claim 4, characterized in that: The substrate bias voltage is -90~-150V; and / or, the thickness of the first Ti-Al-Sn-C layer is 0.1-0.3 μm; And / or, the thickness of the TiC diffusion layer is 0.1-0.2 μm.

6. The preparation method according to claim 1, characterized in that Specifically include: High-power pulsed magnetron sputtering combined with DC magnetron sputtering technology is used, with Ti target, AlSn alloy target and C target as target materials, and inert gas as working gas, to deposit a second Ti-Al-Sn-C layer on the surface of the TiC diffusion layer; wherein the atomic ratio of Al to Sn in the AlSn alloy target is 99:1-70:30, the substrate bias is -100-200V, the high-power pulse duty cycle is 1-10%, the high-power pulse frequency is 200-1000Hz, and the pulse The width is 50~200μs, the Ti target is a high-power pulsed magnetron sputtering target, and the average sputtering power of the Ti target is 80~100W; the AlSn alloy target and the C target are DC magnetron sputtering targets, the DC sputtering power of the AlSn alloy target is 40~70W, and the DC sputtering power of the C target is 40~100W, the gas pressure of the reaction chamber is 0.5-2.0Pa, the deposition temperature is 100~300℃, the deposition time is 4.0~8.0h, and the distance between the substrate and the target is 8~15cm; And, the substrate on which the second Ti-Al-Sn-C layer was deposited was placed in a vacuum of 3×10 -4 Pa below the heat treatment device to carry out secondary vacuum heat treatment, thereby forming Ti2 (Al 1-x Sn x )C solid solution layer; wherein, wherein 0 <x<1。 7. The preparation method according to claim 6, characterized in that: The substrate bias voltage is -90~-120V; and / or, the thickness of the second Ti—Al—Sn—C layer is 1.0 to 3.0 μm; And / or, the Ti2(Al 1-x Sn x )The thickness of the C solid solution layer is 1.1~3.2μm.

8. The conductive, corrosion-resistant solid solution MAX phase composite coating prepared by the preparation method according to any one of claims 1 to 7, characterized in that: The composite coating comprises a Ti transition layer, a TiC diffusion layer and a Ti2 (Al 1- x Sn x )C solid solution layer.

9. The conductive, corrosion-resistant solid solution MAX phase composite coating according to claim 8, characterized in that: The total thickness of the conductive corrosion-resistant solid solution MAX phase composite coating is 1.2-3.5 μm.

10. Use of the conductive, corrosion-resistant solid solution MAX phase composite coating according to claim 8 or 9 in protecting bipolar plates of hydrogen fuel cells.

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