MnCo2O4涂层对SUS430合金连接体的表面改性研究

采用溶胶-凝胶法制得MnCo₂O₄纳米粉体, 通过XRD和TEM分析了粉体的物相和形貌; 通过添加适量乙基纤维素和松油醇经研磨制成浆料, 并采用丝网印刷法涂覆于SUS430基片上, 在900℃下95%N₂+5%H₂气氛中保温3 h, 再于800℃空气气氛中保温10 h烧结得到涂层。采用SEM对涂层的表面和断面进行了观察, 在750℃空气气氛下测试了SUS430/MnCo₂O₄样品的导电性能和抗氧化性能, 最后采用EDS对涂层的断面进行分析。结果表明: MnCo₂O₄粉体为单一的立方尖晶石相, 晶粒大小均匀, 粒径约150 nm; MnCo₂O₄涂层致密,与基体紧密结合且厚度均匀。SUS430/MnCo₂O₄样品在750℃空气气氛下经1000 h氧化后, 氧化增重量仅为0.15 mg/cm², 是SUS430合金氧化增重量的1/6; 面比电阻值为0.026 Ω·cm², 比SUS430合金的面比电阻值低了两个数量级; EDS结果表明: Cr元素主要分布在涂层与合金的界面, 在涂层内部无分布。研究显示, MnCo₂O₄涂层能显著降低SUS430合金基体的氧化速率, 有效改善其在高温下的导电性能, 并成功抑制Cr元素的挥发。

Surface Modification of SUS430 Interconnect with MnCo2O4 Coating

Nano-scale MnCo₂O₄ powder was prepared by means of Sol-Gel method. XRD and TEM were employed to analyze phase composition and microstructure of the MnCo₂O₄ powder. A paste was made of the powder by adding a proper amount of ethyecellulose as binder and terpilenol. The paste was coated on the SUS430 substrate by screen printing method. The MnCo₂O₄ coating on SUS430 alloy was sintered under the atmosphere of 95%N₂ + 5%H₂ at 900℃ for 3 h and then at 800℃ in air for 10 h. SEM was employed to observe the surface and cross-section of the sample with coating. The oxidation resistance and the area specific resistance(ASR) value of the sample was characterized at 750℃ in air. Finally, EDS was employed to analyze the cross-section of the sample. The results show that the powder is in single cubic spinel phase. The grains are homogeneous with size of about 150 nm. The coating that is dense contacts to alloy matrix closely with uniform thickness. After oxidation at 750℃ for 1000 h in air, the weight gain of SUS430/MnCo₂O₄ sample is 0.15 mg/cm², which is only one-sixth that of the SUS430 alloy. The ASR value is 0.026 Ω·cm², two order of magnitude lower than that of SUS430 alloy. EDS results show that Cr is mainly distributed in interface between the coating and alloy, with no distribution in the coating. The MnCo₂O₄ coating can effectively reduce the oxidation rate and improve the conductivity of SUS430 alloy significantly at high temperature, and restrain the volatilization of Cr successfully.