Microstructure evolution and HT molten chloride salts corrosion performance of novel NiAl/Al/Si-NiAl multilayer coatings for CSP application

The microstructure and resistance to high-temperatures molten chloride salt corrosion of NiAl/Al/Si-NiAl coating was investigated. The pre-oxidation integrates NiAl/Al/Si-NiAl multilayer coating into a unified structure, resulting in the formation of a continuous dense oxide layer. During corrosion process, the oxide layer initially grows and thickens, then reaches a stable state, and finally becomes thinner. The mass change remained at approximately −2.5 ± 0.2 mg/cm² after 162 h of corrosion. The structural design of the multi-layer coating further increases the thickness of the Al₂O₃ layer and strengthens the coating’s resistance corrosion. This fully utilizes the role of the pure Al layer as Al source and also takes advantage of Si addition to promote the formation of Al₂O₃ layer and hinder the diffusion of Cr.