High temperature corrosion of TiAlN multilayer coatings by solid NaCl

Protection of mechanical parts in marine high-salt environment is a difficult issue．Coating technology is an effective means to improve corrosion resistance of key parts．HIPIMS coupled with multi-arc ion plating technology were used to deposit TiAlN/Me multilayer coatings．Effects of metal tie-layer on thermal corrosion resistance of coatings were studied．Morphology and structure of coatings were characterized by SEM, XRD and XPS．Corrosion resistance was tested in air environment through a solid salt film at 500 ℃．TiAlN/Ti coatings were found to demonstrate super-low porosity and corrosion, being 24.046- and 23.041-fold more corrosion-resistant than 304-steel and Ti-6Al-4V substrate respectively．Due to widely distributed defects in TiAlN/TiAl coating, relative corrosion area accounted for 67.090 %．It is worth noting that titanium is more suitable for tie-layer within multilayer coatings than alloy TiAl, due to excellent surface roughness and low porosity．This is of vital importance to its high temperature corrosion resistance．