Tribological Properties and Corrosion Resistance of Multilayer a-C:H:Ti Films at Different Target Currents

To meet the requirements of friction and corrosion resistance performance of helicopter transmission bearings under harsh environments, Ti/TiN/Ti-DLC multilayer composite films were prepared on a 40Cr15Mo2VN substrate by a non-equilibrium magnetron sputtering technique. The effects of different titanium currents on the structure, mechanical properties, and friction properties of the films were investigated by SEM, Raman spectroscopy, and nanoindentation. Moreover, the tribological and corrosion resistance of developed films under acidic conditions were investigated. The results show that the sp(3)-C/sp(2)-C ratio in the films gradually decreases with increasing Ti current from 0 A to 2 A, leading to decreased hardness and elastic modulus. The bonding force of the DLC films also gradually increases with increasing Ti current and reaches the maximum value of 41.69 N at 2 A; the friction coefficient of the films gradually decreases under a load of 20 N. In summary, the best performance of thin film at Ti-2 A was compared with the corrosion and wear performance of thin film and substrate in acetic acid solution and aqueous solution at Ti-2 A. The wear amount of thin film and substrate in aqueous solution is significantly lower than in acetic acid solution, and the corrosion potential of thin film is higher than that of substrate in both solutions, which can play a protective role against the substrate.