Effect of Mo Addition and Water Vapor on the High-Temperature Corrosion Performance of APS Ni-Al-based Coatings

To investigate the influence of Mo addition and water vapor content on the high-temperature corrosion resistance of Ni-Al-based coatings, 0Mo, 5Mo, and 10Mo coatings were deposited by APS thermal spray onto stainless steels. The chlorine-induced corrosion test was conducted in an experimental environment simulating a biomass boiler. The results show that adding the Mo element lowers the coating's ability to resist corrosion without water vapor. The coating is more prone to peeling because Mo prevents the coating from eventually forming a protective oxide layer. Water vapor significantly speeds up the production of oxides and modifies their morphology and structure. The combined effects of Mo and water vapor increase the coating's ability to resist corrosion. The development of thick and protective Ni and Al oxide layers on the coated surface is aided by the acceleration of oxide production by water vapor and the alteration of oxide structure by Mo components.