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系统地研究了Ni-Cr-W高温合金铝覆涂层在1100℃的恒温氧化行为。利用扫描电子显微镜(SEM)和X射线衍射(XRD)等技术对试样进行观察与分析。结果表明,铝覆涂层的氧化动力学曲线分为初期快速氧化阶段和中后期缓慢平稳氧化阶段。在整个氧化过程中,铝覆涂层表面形成的氧化物经历了由晶须状的θ-A12O3→等轴的α-A12O3→α-A12O3→颗粒状α-A12O3→颗粒状团聚α-A12O3变化过程。碳化物在氧化初期可有效阻止由Ni和Al元素的互扩散所引起的涂层退化。
The isothermal oxidation behavior of Ni-Cr-W superalloy coated at 1100 ℃ was studied systematically. The samples were observed and analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the oxidation kinetics curve of aluminum coating is divided into initial rapid oxidation stage and slow steady oxidation stage. During the entire oxidation process, the oxide formed on the surface of the aluminum coating undergoes a change from the whisker-like θ-A12O3 → the equiaxed α-A12O3 → α-A12O3 → granular α-A12O3 → granular agglomerated α-A12O3 process. Carbides can effectively prevent coating degradation caused by the mutual diffusion of Ni and Al elements in the initial stage of oxidation.