Comparison of high temperature hot corrosion behavior of AlCoCrFeNiTi and AlCoCrFeNiZr high entropy alloy (HEAs) coatings

Abstract

Composite coating technologies used in the aircraft industry are susceptible to hot corrosion damage caused by substandard fuels and harsh environmental conditions. In this context, it is crucial to evaluate the hot corrosion resistance of coating systems and to study the microstructural changes. Recent research has focused on the hot corrosion damage behavior of high entropy alloy (HEAs) coatings in the aircraft industry. In this study, two different HEA coating systems were designed by applying CoNiCrAlY powder, AlCoCrFeNiTi and AlCoCrFeNiZr HEA powders to an Inconel 718 substrate using two thermal spray coating techniques (high velocity oxy fuel (HVOF) and atmospheric plasma spray (APS)). Then, in order to investigate the microstructural changes in the coatings, a salt mixture of 45 % Na2SO4 and 55 % V2O5 was placed on the surface of the coatings and subjected to isothermal hot corrosion experiments at 900 degrees C for 1, 3, 5 and 10 h. Both coating systems exhibited outstanding stability, strength and increased corrosion resistance under high temperature, extremely corrosive conditions, and the damage effect in needle/rod-like hot corrosion was dominated by the formation of Co2VO4 compound as a corrosion product.