Influence of Al content on microstructure, mechanical and tribological properties of Ti-W-Al-N composite films. (March 2017) - Yu, Lihua
Abstract: Ti-W-Al-N films with various Al content (0 at.% ∼ 12.4 at.%) were deposited by reactive magnetron sputtering. The composition, microstructure, mechanical and tribological properties of Ti-W-Al-N films were investigated by EDS, XRD, HRTEM, SEM, Nano-indentation, Ball-on-disk tribometer. It is found that Ti-W-Al-N films consist of Ti-W-Al-N phase, Ti2 N phase and W2 N phase below 2.9 at.% Al. Ti2 N phase disappears at 5.6 at.% Al and h-AlN phase forms at 12.4 at.% Al respectively. The hardness firstly increases and then decreases with increasing Al content and the highest hardness is 35.7 GPa at 8.7 at.% Al. At room temperature, the friction coefficient continuously increases, whereas the wear rate firstly decreases and then increases with increasing Al content. The lowest wear rate of 1.79 × 10 −8 mm 3 N −1 mm −1 is obtained at 8.7 at.% Al. As the temperature increases from room temperature to 700 °C, the friction coefficient firstly increases and then decreases, while the wear rate gradually increases. The tribological properties of the film depended on the testing temperatures significantly because the testing temperatures influenced the hardness, the tribo-films and wear mechanism of the film. Highlights: TiWAlN films exhibit various microstructures depending on different Al content. The film with 15.9 at.% Al has the highest hardness and the lowest wear rate at 25 °C. The TiWAlN films with Al have higher oxidation resistance temperature.