Reaction Mechanism of Superalloy K403 Corroded by Zinc Sulfide

The corrosion of nickle superalloy by leaked zinc sulfide powders during hot pressing is the dominant factor which reduces the life time of the molds.In this work,the corrosion products were investigated by SEM and EDS.The corrosion procedure was evaluated on the aspects of both thermodynamics and kinetics.The results indicate that the vapor pressure of the produced zinc gas and the system temperature influence the reaction equilibrium.The liquid nickel sulfide at high temperature accelerates the reaction by transporting nickel to zinc sulfide surface.This study suggests that the corrosion resistance of the superalloy molds can be promoted by decreasing the system temperature or increasing the zinc vapor pressure.