Codeposition of Co-Al-Y on nickel base superalloys by pack cementation process

Based on the results of thermochemical analysis, NH4I + NH4Cl proved to be a more favorable activator for codepositing Co-Al-Y compared to NH4I or NH4Cl. Coating deposition experiments were also demonstrated that codeposition of Co-Al-Y with high concentration of Co and minute quantities of Y could be achieved at 1323 K in the NH4I + NH4Cl activated packs. The coating exhibited the best cyclic oxidation resistance at 1323 K when NH4I + NH4Cl were used as activator.