Friction and Wear Behaviors of Nano and Microscale-Structured Al₂O₃-TiO₂ Coatings

Nano-structured and microscale-structured Al₂O₃-TiO₂ coatings were prepared by air plasma spraying (APS). The friction and wear behaviors of the two coatings at different loads were investigated with SRV friction and wear testing machinery. The micro structure, the porosity, the micro-hardness and bonding strength of the coatings were investigated as well. The wear mechanism was studied from the morphology of triturate. Results show that the microstructure of the nano-structured Al₂O₃-TiO₂ coatings consist of two distinct regions. One is formed from completely melted agglomerated power and the other is incompletely melted with a particulate microstructure retained from the starting agglomerates, and the properties of micro hardness and bonding strength of the nano-structured coating is better than the microscale-structured Al₂O₃-TiO₂ coating. The friction coefficient decreases with the increase of load, and the triturate will become fine, uniform and round under high load, which improves the contacting state between the friction pair.