The Influence of Working Pressure on the Structure, Mechanical Properties, and Tribological Properties of TiN Coatings

Abatract: TiN coatings were deposited on substrates such as 9Cr18 steel using high-power pulsed magnetron sputtering (HiPIMS) technology. The variation of working pressures on microstructure, mechanical properties, and tribological properties of the coatings were systematically studied. As the working pressure increased, the surface of TiN coating became smooth and flat, resulting in an the surface density of the coatings first increase and then decrease, but the cross-sectional morphology of the coating all exhibited the dense structure. The preferred orientation of TiN coatings always were the (111) plane and the element content in the coating was evenly distributed, with an N element content of around 70 %. When the working pressure was 0.7 Pa, the coating had the highest hardness (about 30 GPa) and the elastic modulus of it (about 280.6 GPa). At the same time, the coating exhibited excellent fracture resistance with H/E ratio of 0.106, showing significant advantages in the nitride coatings. As the working pressure increased, the adhesion strength between the coatings and the substrate gradually increases. When the working pressure was 0.94 Pa, the coating exhibited the highest adhesion strength (about 52 N) between the coatings and the substrate. Besides, the friction coefficient of coatings under different working pressures were similar, and the minimum friction coefficient of coatings was 0.115. When the working pressure was 0.7 Pa, the coating exhibited the lowest wear rate about 1.93×10⁻⁷ mm³/(N·m).