A rare earth oxide-inert metal-spinel conductive composite coating and preparation method thereof

Abstract

The present invention relates to the field of high-temperature conductive protective coatings, specifically a rare earth oxide-inert metal-spinel conductive composite coating and a preparation method. The conductive composite coating comprises a rare earth high-temperature oxidation resistant layer, an inert metal diffusion barrier layer and an alloy thermal conversion spinel layer. The conductive composite coating can not only improve the high-temperature oxidation resistance of the stainless steel substrate, but the inert metal diffusion barrier layer can also inhibit the mutual diffusion of elements between the substrate and the alloy thermal conversion spinel layer, thereby improving the service performance of the coating. The conductive composite coating adopts a combination of multi-target co-sputtering and thermal conversion to achieve the integrated preparation of the rare earth high-temperature oxidation resistant layer, the inert metal diffusion barrier layer and the alloy thermal conversion spinel layer.

Description

Technical Field

[0001] The invention relates to the field of high-temperature conductive protective coatings, in particular to a rare earth oxide-inert metal-spinel conductive composite coating and a preparation method thereof. Background Art

[0002] As an important component of solid oxide fuel cells, the performance of the interconnector directly affects the service performance and service life of the battery. However, due to the lack of antioxidant capacity, high surface resistivity, and the volatilization of chromium in the alloy that poisons the cathode, the application of ferritic stainless steel in solid oxide fuel cells is limited. In order to solve these problems, attempts have been made to improve the performance of the interconnector by coating it with a high-temperature conductive protective coating. By preparing a protective coating on the surface of stainless steel, its antioxidant capacity can be enhanced, the surface resistivity can be reduced, and the working efficiency of the battery can be improved. Despite this, some studies have pointed out that during the service of the interconnector, there is a phenomenon of element interdiffusion between the substrate and the high-temperature conductive protective coating, especially Cr in the substrate will diffuse into the coating and undergo an interfacial reaction, resulting in a decrease in the chemical stability, conductivity and high-temperature oxidation resistance of the coating. Therefore, a high-temperature oxidation resistance layer and a diffusion barrier layer are prepared between the stainless steel substrate and the high-temperature conductive protective coating to improve the high-temperature oxidation resistance of the substrate and inhibit the interdiffusion of elements. The rare earth high-temperature oxidation resistance layer can improve the high-temperature oxidation resistance of the stainless steel substrate, and the inert metal diffusion barrier layer can inhibit the interdiffusion of elements between the substrate and the conductive protective coating, thereby improving the service performance of the coating. Summary of the invention

[0003] The object of the present invention is to provide a conductive composite coating and a preparation method that can improve high-temperature oxidation resistance and inhibit element interdiffusion. The rare earth high-temperature oxidation resistance layer can improve the high-temperature oxidation resistance of the substrate. The inert metal diffusion barrier layer has good density and can effectively inhibit the element interdiffusion between the rare earth high-temperature oxidation resistance layer and the alloy thermal conversion spinel layer, thereby improving the service performance of the composite coating and avoiding the decrease in the mechanical properties of the substrate due to interdiffusion.

[0004] The technical solution adopted by the present invention is:

[0005] A rare earth oxide-inert metal-spinel conductive composite coating and a preparation method thereof. The conductive composite coating comprises a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and an alloy thermal conversion spinel layer.

[0006] The rare earth oxide-inert metal-spinel conductive composite coating has a rare earth high temperature oxidation resistant layer and an inert metal diffusion barrier layer with thicknesses of 0.2 μm to 1 μm and 0.03 μm to 0.2 μm, respectively. The alloy thermal conversion spinel layer has a spinel structure, a thickness of 5 μm to 20 μm, and good electrical conductivity.

[0007] The method for preparing a rare earth oxide-inert metal-spinel conductive composite coating comprises the following steps: step one is to prepare a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and a conductive alloy layer by multi-target co-sputtering; step two is oxidation treatment.

[0008] The method for preparing the rare earth oxide-inert metal-spinel conductive composite coating comprises the following steps in step 1:

[0009] Matrix pretreatment: first polish it with 240~800# SiC sandpaper, then ultrasonicate it in ethanol for 10~20min, and finally dry it thoroughly in a dryer;

[0010] Multi-target co-sputtering: hang the sample in a vacuum chamber, maintain the argon pressure of the vacuum chamber at 0.1~0.6Pa, and the oxygen pressure at 2~6Pa, turn on the RF power supply and the rare earth oxide target baffle, the target power range is 150W-500W, and deposit for 1~2 hours, close the oxygen and rare earth oxide target baffles, maintain the argon pressure of the vacuum chamber at 0.1~0.6Pa, open the inert metal target baffle, the target power range is 150W-500W, and deposit for 0.5~1 hour, close the inert metal target baffle, open the alloy target baffle, the target power range is 150W-500W, and deposit for 1~4 hours.

[0011] The method for preparing a rare earth oxide-inert metal-spinel conductive composite coating comprises the following steps: placing the substrate in a muffle furnace and keeping it warm for 1 to 20 hours at a temperature of 500 to 800°C, so that the conductive alloy layer is converted into an alloy thermally converted spinel layer.

[0012] The beneficial effects of the present invention are:

[0013] 1. The rare earth high temperature oxidation resistant layer can improve the high temperature oxidation resistance of the substrate, and the inert metal diffusion barrier layer can inhibit the mutual diffusion of elements between the rare earth high temperature oxidation resistant layer and the alloy thermal conversion spinel layer, thereby improving the service performance of the conductive composite coating.

[0014] 2. The preparation process adopts a combination of multi-target co-sputtering and thermal conversion, which can realize the integrated preparation of rare earth metal high-temperature oxidation layer, inert metal diffusion barrier layer and alloy thermal conversion outer layer, simplifying the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the cross section of stainless steel substrate / chromium oxide / rare earth high temperature resistant oxidation layer / inert metal diffusion barrier layer / alloy thermal conversion spinel layer prepared by magnetron sputtering technology.

[0016] Figure 2This is the XRD spectrum of the rare earth oxide-inert metal-spinel conductive composite coating.

[0017] Figure 3 This is the oxidation kinetic curve of rare earth oxide-inert metal-spinel conductive composite coating. DETAILED DESCRIPTION

[0018] A rare earth oxide-inert metal-spinel conductive composite coating of the present invention comprises a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and an alloy thermal conversion spinel layer; rare earth oxide is used as the rare earth high temperature oxidation resistant layer, including but not limited to cerium oxide, lanthanum oxide, yttrium oxide, neodymium oxide, etc., with a thickness of 0.2μm to 1μm; inert metal is used as the inert metal diffusion barrier layer, with a thickness of 0.03μm to 0.2μm; the alloy thermal conversion spinel layer material has a spinel structure, with a thickness between 5μm and 20μm.

[0019] The base alloy was polished with 240~800# SiC sandpaper, then ultrasonicated in ethanol for 10~20 minutes, and finally fully dried in a dryer. Then, a rare earth high-temperature oxidation resistant layer, an inert metal diffusion barrier layer and a conductive alloy layer were prepared by multi-target co-sputtering using magnetron sputtering. Finally, the conductive alloy layer was converted into an alloy thermal conversion spinel layer by oxidation treatment.

[0020] The present invention is further described in detail below through examples and drawings.

[0021] Example 1

[0022] The substrate is made of SUS430 ferritic stainless steel, and the substrate sample is 15mm×11mm×2mm. The substrate is polished with 240~800# SiC sandpaper, then ultrasonicated in ethanol for 10 minutes, and finally fully dried in a dryer; the pretreated substrate is hung in a vacuum chamber, the argon pressure in the vacuum chamber is maintained at 0.5Pa, the oxygen pressure is 4Pa, the RF power supply and the cerium oxide target baffle are turned on, the target power range is 300W, and the deposition is carried out for 2 hours, the oxygen and cerium oxide target baffles are turned off, the argon pressure in the vacuum chamber is maintained at 0.5Pa, the platinum target baffle is turned on, the target power range is 400W, and the deposition is carried out for 0.5 hours, the platinum target baffle is turned off, the iron-cobalt-nickel alloy target baffle is turned on, the target power range is 200W, and the deposition is carried out for 4 hours; finally, the substrate is placed in a muffle furnace and kept warm for 12 hours at a temperature of 800℃.

[0023] like Figure 1 As shown, the conductive composite coating includes a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and an alloy thermal conversion spinel layer.

[0024] Example 2

[0025] The substrate is made of E-Brite stainless steel, and the substrate sample is 15mm×11mm×2mm. The substrate is polished with 240~800# SiC sandpaper, then ultrasonicated in ethanol for 15 minutes, and finally fully dried in a dryer; the pretreated substrate is hung in a vacuum chamber, the argon pressure in the vacuum chamber is maintained at 0.6Pa, the oxygen pressure is 6Pa, the RF power supply and the yttrium oxide target baffle are turned on, the target power range is 300W, and the deposition is carried out for 1 hour, the oxygen and yttrium oxide target baffles are turned off, the argon pressure in the vacuum chamber is maintained at 0.6Pa, the silver target baffle is turned on, the target power range is 400W, and the deposition is carried out for 1 hour, the silver target baffle is turned off, the iron-cobalt-nickel alloy target baffle is turned on, the target power range is 300W, and the deposition is carried out for 2 hours; finally, the substrate is placed in a muffle furnace and kept warm for 10 hours at a temperature of 600°C.

[0026] like Figure 2 As shown, the conductive composite coating was subjected to phase analysis, and the results showed that the alloy thermally transformed spinel layer had a spinel structure.

[0027] Example 3

[0028] The substrate is Crofer22APU ferritic stainless steel, and the substrate sample is 15mm×11mm×2mm. The substrate is polished with 240~800# SiC sandpaper, then ultrasonicated in ethanol for 10 minutes, and finally fully dried in a dryer; the pretreated substrate is hung in a vacuum chamber, the argon pressure in the vacuum chamber is maintained at 0.4Pa, the oxygen pressure is 2Pa, the RF power supply and the lanthanum oxide target baffle are turned on, the target power range is 200W, and the deposition is carried out for 2 hours, the oxygen and lanthanum oxide target baffles are turned off, the argon pressure in the vacuum chamber is maintained at 0.4Pa, the platinum target baffle is turned on, the target power range is 200W, and the deposition is carried out for 1 hour, the platinum target baffle is turned off, the copper-iron alloy target baffle is turned on, the target power range is 200W, and the deposition is carried out for 4 hours; finally, the substrate is placed in a muffle furnace and kept warm for 16 hours at a temperature of 600℃.

[0029] like Figure 3 As shown, after using the rare earth oxide-inert metal-spinel conductive composite coating, the oxidation rate constant of the conductive composite coating is significantly reduced, thereby extending its service life.

[0030] Example 4

[0031] The substrate is Crofer22APU ferritic stainless steel, and the substrate sample is 15mm×11mm×2mm. The substrate is polished with 240~800# SiC sandpaper, then ultrasonicated in ethanol for 20 minutes, and finally fully dried in a dryer; the pretreated substrate is hung in a vacuum chamber, the argon pressure in the vacuum chamber is maintained at 0.4Pa, the oxygen pressure is 4Pa, the RF power supply and the cerium oxide target baffle are turned on, the target power range is 400W, and the deposition is carried out for 2 hours, the oxygen and cerium oxide target baffles are turned off, the argon pressure in the vacuum chamber is maintained at 0.4Pa, the silver target baffle is opened, the target power range is 500W, and the deposition is carried out for 1 hour, the silver target baffle is closed, the manganese-cobalt alloy target baffle is opened, the target power range is 400W, and the deposition is carried out for 4 hours; finally, the substrate is placed in a muffle furnace and kept warm for 16 hours at a temperature of 600°C.

[0032] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A rare earth oxide-inert metal-spinel conductive composite coating, characterized in that: The composite coating on the substrate includes a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and an alloy thermal conversion spinel outer layer; The method for preparing the rare earth oxide-inert metal-spinel conductive composite coating comprises the following steps: step 1 is to prepare a rare earth high temperature oxidation resistant layer, an inert metal diffusion barrier layer and a conductive alloy layer by multi-target co-sputtering, and step 2 is oxidation treatment; The process 1 comprises the following steps: (1) substrate pretreatment: firstly grinding the substrate with 240-800# SiC sandpaper, then ultrasonicating in ethanol for 10-20 minutes, and finally fully drying with a dryer; (2) multi-target co-sputtering: hanging the substrate in a vacuum chamber, maintaining the argon pressure of the vacuum chamber at 0.1-0.6 Pa, the oxygen pressure at 2-6 Pa, turning on the RF power supply and the rare earth oxide target baffle, the target power range is 150W-500W, depositing for 1-2 hours, turning off the oxygen and rare earth oxide target baffle, maintaining the argon pressure of the vacuum chamber at 0.1-0.6 Pa, turning on the inert metal target baffle, the target power range is 150W-500W, depositing for 0.5-1 hour, turning off the inert metal target baffle, turning on the alloy target baffle, the target power range is 150W-500W, and depositing for 1-4 hours; The rare earth oxide target is a cerium oxide target, a yttrium oxide target or a lanthanum oxide target; The inert metal target is a platinum target or a silver target; The alloy target material is an iron-cobalt-nickel alloy target, a copper-iron alloy target or a manganese-cobalt alloy target; The second step comprises: placing the substrate in a muffle furnace and keeping it warm for 1 to 20 hours at a temperature of 500 to 800° C., so that the conductive alloy layer is converted into an alloy thermal conversion spinel layer.

2. The rare earth oxide-inert metal-spinel conductive composite coating according to claim 1, characterized in that: The rare earth high temperature oxidation resistant layer has a thickness of 0.2 μm to 1 μm.

3. The rare earth oxide-inert metal-spinel conductive composite coating according to claim 1, characterized in that: The thickness of the inert metal diffusion barrier layer is 0.03 μm to 0.2 μm.

4. The rare earth oxide-inert metal-spinel conductive composite coating according to claim 1, characterized in that: The thickness of the alloy thermally converted spinel outer layer is between 5 μm and 20 μm.

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