Formation of Alumina Layer on Fe-Cr-Ni Alloy by Pack Cementation and Oxidation

摘要

To protect Fe-Cr-Ni based alloy from high temperature corrosion in carbon containing atmosphere at elevated temperature, alumina coating was prepared on the Fe-Ni-Cr alloy substrate by pack cementation and oxidation. Results showed that a surface FeAl layer formed after the pack cementation process, and an Al_2O_3 coating formed by selective oxidation of the FeAl layer. The coating adhered tightly to the FeAl layer without any cracks or porous inbetween them. By the oxidation process the catalytic elements such as Fe and Ni were remarkably reduced from the surface. Further anti-coking test indicated that the alumina scale could successfully inhibit the outward diffusion of catalytic elements and showed excellent coking resistance.