Effects of temperature on tribological properties of nanostructured and conventional Al2O3–3 wt.% TiO2 coatings

Nanostructured and conventional Al2O3–3 wt.% TiO2 coatings were deposited by atmosphere plasma spraying. The tribological properties of both coatings against a silicon nitride ball were examined in the temperature range from room temperature to 600 °C. The friction coefficients of both coatings were similar and ranged from 0.85 to 0.10. The wear rates of both coatings increased with the increase in temperature. At room temperature, a protective layer consisting of silicon oxide existed on the worn surface of both coatings and led to the lower wear rate. At high temperature, brittle fracture occurred on the worn surfaces of both coatings, which was enhanced with the increase of temperature. But, the wear resistance of the nanostructured coating was superior to that of the conventional coating except at room temperature. The improvement in wear resistance of the nanostructured Al2O3–3 wt.% TiO2 coating was discussed in the terms of its microstructural characteristics.