NaCl-induced hot-corrosion behavior of TiAlN single-layer and TiAlN/Ti multilayer coatings at 500 °C

The microstructure and corrosion behavior of the TiAlN and the TiAlN/Ti coatings were studied under the synergistic effects of salt spray and high temperature at 500 °C. The results showed that the salt spray test accelerated the hot corrosion process of the coatings. The columnar grain boundaries of TiAlN coatings provide a preferred position for internal corrosion, where the corrosion product was mainly composed of TiO 2 . The TiAlN/Ti multilayer interface and Ti interlayer have double effects on the hot corrosion resistance of the coating. The Ti metal layer restrained the corrosion zone propagation to TiAlN layer and also aggravated the local corrosion inside the coating. The corrosion mechanisms of TiAlN and TiAlN/Ti coatings were discussed in detail. • The hot corrosion behaviors of TiAlN single-layer and TiAlN/Ti multilayer coatings were investigated. • During the hot corrosion process, the Ti and Al elements were consumed greatly, and no complete and protective oxide layer was formed. • The columnar grain boundaries of TiAlN coating provide favorable position for internal corrosion. • Ti metal layer was preferentially corroded in TiAlN/Ti coating. It provides a reference for the development of new nitride coatings.