Mechanical Properties and Sand Erosion Damage Mechanism of TiN/Ti Multilayer Coatings after Thermal Cycling Treatment

TiN/Ti multilayer coatings have great potential for application in improving aero-engine service lives in the sand environment. In this study, TiN/Ti multilayer coatings have been deposited on Ti6Al4V alloy by the magnetic filter cathode vacuum arc deposition technique. The microstructure, adhesion strength, microhardness and sand erosion properties of such coatings after different thermal cycling treatment at 500 °C have been characterized. The results showed that the adhesion strength decreased by 4.6, 4.6, and 41.5% for the coatings after treatments designated as 500-1, 500-2, and 500-3 (where 500 denotes the temperature in and -X denotes the number of cycles) compared with that of 500-0. The corresponding microhardness decreased by 13.5, 20.5, and 51.0%, and the erosion rate increased by factors of 2.51, 24.1, and 124.1. The degradation in mechanical properties was mainly attributed to the onset of surface oxidation, a loosening of the interface structure, and the development of interface microcracks.