Transient Oxide Formation on APS NiCrAlY After Oxidation Heat Treatment

• DOI: 10.1007/s11666-010-9602-0
• Publication Date: 2010-12-02T21:00:24Z
• Authors: Philip Puetz; Xiao Huang; Q. Yang; Z. Tang
• Keywords: Continuous layers; Alumina; Alumina layers; Oxidation heat; Oxide formation; Surface oxide; 02 engineering and technology; surface oxide formation; High temperature; Heat treatment; Heat treatment temperature; NiCrAlY; Oxidation; Continuous films; NiCrAlY coating; 0210 nano-technology; Oxidizing environments

In this study, the transient surface oxide formation on APS NiCrAlY samples was examined after oxidation heat treatment at temperatures between 1000 and 1100 °C. The surface oxides observed on the NiCrAlY surface included a sporadic top layer of NiO and a continuous layer of alumina immediately adjacent to the NiCrAlY coating. Cr-rich oxide in smaller quantities than alumina was also found surrounding the NiO and dispersed within alumina. The alumina assumed whisker-shaped morphology when being observed from the surface but formed continuous film along the NiCrAlY surface. Although the formation of alumina has been observed on all the samples examined in this study, the NiCrAlY sample heat treated at 1050 °C for 5 h generated more continuous α-alumina layer and also contained less surface NiO and Cr-rich oxide. Based on the results, it is believed that NiO developed first upon exposure to an oxidizing environment at high temperature, and stable alumina began to form with the increase in heat treatment temperature and time.