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采用普通空气对离子渗氮的42CrMo钢进行离子后氧化处理。利用光学显微镜、扫描电镜(SEM)、X射线衍射仪、电化学性能分析测试仪对复合渗层的显微组织、厚度、物相、表面形貌及耐蚀性进行了测试和分析。研究结果表明,普通空气可用作42CrMo钢离子后氧化处理的气源;通过离子后氧化处理,在经离子渗氮的42CrMo钢氮化层上形成一层厚度为1~2μm、由Fe2O3和Fe3O4组成的氧化层;随氧化时间延长或温度增高,氮化层化合物相分解,化合物层厚度逐渐减小,后氧化时间和温度对氧化层的Fe2O3和Fe3O4比例起决定作用。同时,离子后氧化能显著改善渗氮42CrMo钢的耐蚀性,其中工艺参数为400℃、氧化60 min获得最佳耐蚀性。
Ionized nitrided 42CrMo steel was ionized and oxidized with normal air. The microstructure, thickness, phase, surface morphology and corrosion resistance of the composite layer were tested and analyzed by optical microscope, scanning electron microscope (SEM), X-ray diffraction and electrochemical analyzer. The results show that ordinary air can be used as the gas source for the post-oxidation treatment of 42CrMo steel. After ion post-oxidation treatment, a layer of 1 ~ 2μm thickness is formed on the nitrided layer of 42CrMo steel after ion nitriding and is composed of Fe2O3 and Fe3O4 With the oxidation time prolonging or increasing the temperature, the nitrided layer compound decomposes and the thickness of the compound layer gradually decreases. The post-oxidation time and temperature play a decisive role in the ratio of Fe2O3 and Fe3O4 in the oxide layer. At the same time, the post-oxidation can significantly improve the corrosion resistance of the nitrided 42CrMo steel, in which the optimum corrosion resistance is achieved by the oxidation of 60 min at 400 ℃.