Effects of sputtering gas on microstructure and tribological properties of titanium nitride films

Titanium nitride (TiN) films can be utilized as hard and protective coatings for synchronizer ring, which is the key components of the car gearbox. The tribological properties of synchronizer ring play a key role in the safety and reliability of the car shifting system. The aim of the present work is to improve tribological properties of synchronizer ring and investigate effects of depositing gas on preferred orientation, surface morphology, surface roughness and tribological properties of TiN thin films. The as-prepared films are deposited on copper alloy (TL084) and Si (100) substrates by a closed field unbalanced magnetron sputtering system. The different sputtering gas with the volume ratio of argon to nitrogen of 1:3, 1:2 and 1:1 is employed. Results indicated that the increasing argon concentration in the gas mixture promotes the growth of TiN nanocrystallines and reduces its surface roughness, friction coefficient and wear rate. TiN films have the (200) preferred orientation at low argon concentration, while the (111) preferred orientation dominates at high argon concentration. TiN thin films deposited with the ratio of argon to nitrogen of 1:1 has the best tribological properties, which are the best sputtering condition as an ideal functional coating for synchronizer ring.