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采用普通空气对42CrMo钢离子渗氮样进行了离子后氧化处理。采用金相、扫描电镜、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、渗层厚度、物相、耐蚀性及电化学试验后试样表面进行了测试和分析。研究结果表明,对42CrMo钢离子渗氮样进行空气后氧化处理可在氮化层表面形成一层1~2μm厚、由Fe3O4和Fe2O3组成的氧化层,且两种氧化物比值由后氧化工艺参数决定,400℃、60min后氧化时生成的氧化层Fe3O4含量最大,电化学实验后的试样表面没有出现点蚀现象,由此获得最佳耐蚀性。高含量Fe3O4基于该条件下生成Fe3O4的化学反应的吉布斯自由能较小。结果还发现随后氧化时间延长或温度升高,离子氮化层厚度逐渐减薄。
Using ordinary air 42CrMo steel ion nitriding samples after ion oxidation. The microstructure, layer thickness, phase, corrosion resistance and the surface of the sample after electrochemical test were tested and analyzed by metallographic examination, scanning electron microscopy, X-ray diffraction and electrochemical analyzer. . The results show that after the air oxidation of 42CrMo steel ion nitriding, a layer of 1 ~ 2μm thick oxide layer composed of Fe3O4 and Fe2O3 is formed on the surface of the nitride layer, and the ratio of the two oxides is determined by the post-oxidation process parameters It is determined that the oxide layer Fe3O4 generated after oxidation at 400 ° C for 60min has the largest content, and no pitting corrosion occurs on the surface of the sample after the electrochemical experiment, thereby obtaining the best corrosion resistance. The high Gibbs free energy of Fe3O4 based on the chemical reaction of Fe3O4 under this condition is small. The results also found that subsequent oxidation time or temperature increases, the thickness of the ion nitriding layer is gradually thinning.