Preparation, Structures and Tribological Properties of Plasma Sprayed Al₂O₃/TiO₂ Nanacomposite Coatings

Series of Al₂O₃/TiO₂ nanocomposite powders synthesized by sol-gel method were spray dried, and series of nanocomposite coatings were prepared by plasma spraying using the spray dried powders. The nanocomposite coating had a dual-zone nanocomposite structures with semi-molten zone and melting zone. The friction and wear properties of the coatings were investigated on a UMT-2MT tester. The results indicated that the wear rate of the coatings first decreased and then increased with the increasing TiO₂ content, and the coating with 10% TiO₂ had the lowest wear rate. The friction coefficients of the coatings were in the range of 0.6 to 0.8. The wear mechanism of the nanocomposite coating was mainly due to the spalling caused by crack propagation.