包埋法Co-Cr-Y改性高温合金GH586渗铝涂层高温氧化行为

High temperature oxidation behavior of Co-Cr-Y-modified Aluminide Coatings on Ni-based superalloy by pack cementation process

摘要:

通过粉末包埋法运用Co-Cr-Y对高温合金GH586渗铝涂层进行改性，并进行了高温氧化行为的研究。研究结果表明：经Co-Cr-Y改性后的渗铝涂层在1000 °C氧化100h后，其平均增重为0.36毫克/平方厘米，远远低于基体的增重量。经X射线衍射分析，涂层的主要物相为NiAl，在1000 °C氧化过程中生成了连续而致密的氧化膜，主要包含 Al2O3, Cr2O3和 CoCr2O4。通过扫描电镜观察涂层表面和截面的形貌，可以涂层比基体展现出了更为优秀的氧化性能。另外发现，氧化过程中的富Cr（W）在晶界上聚集，有利于为涂层生成连续而致密的氧化膜不断提供Cr元素，从而提高涂层高温氧化性能。

关键词:高温合金;氧化行为;表面改性;涂层

Abstract:

In this work the microstructures and high temperature oxidation behaviors of Co-Cr-Y modified pack aluminide coatings on Ni-based superalloy GH586 were investigated. The results indicated that the specific Co-Cr-Y-modified aluminide coating had a mass gain of only 0.36 mg/cm₂ after oxidation at 1000 °C for 100 h, it was much less than that of the substrate at 1000 °C. From the X ray diffraction the phases of the coatings were mainly AlNi, and after oxidation for 100h at 1000 °C the denser oxidation scale was composed of Al₂O₃, Cr₂O₃, and CoCr₂O₄. The surface and cross sectional morphologies were characterized by scanning electron microscope (SEM). The coating exhibited the better high temperature oxidation resistance, compared to the oxidation film of GH586 without coating. Moreover, the growing Cr (w) rich phase was gradually gathered in the grain boundaries during the oxidation, it is beneficial to provide more Cr element for the dense oxidation film, which is mainly attributed to the excellent high temperature oxidation resistance.

Key words:Superalloy; Oxidation behavior; Surface modification; Coating.