Influence of annealing temperature on thermal stabilities of hydrogenated amorphous carbon on silicon nitride balls

• Annealing treatment was carried out on a-C:H films on silicon nitride balls.
• Changes in structure, mechanical and tribological properties of the films were evaluated.
• Tribochemical reactions on the ball surface during the friction were discussed.

Hydrogenated amorphous carbon films were synthesized on silicon, silicon nitride (Si3N4) ceramic balls and SUS304 by using linear ion beam deposition technology. To investigate the annealing effect on the thermal stabilities of the films on Si3N4 balls, Raman spectroscopy, Fourier transformation infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), nanoindentation, stylus profiler and ball-on-disk friction test were adopted. The results showed that the annealing temperatures had no significant influence on the structure, mechanical and tribological properties of the films until 200 °C. When the temperature was above 200 °C, the film structure changes as effusion of hydrogen and graphitization leading to poor mechanical and tribological properties. Roles of the tribochemical reactions occurred on Si3N4 ball surface during the friction in the tribological properties of hydrogenated amorphous carbon films were discussed.