Abstract:The Ni-based alloy composite coatings reinforced by nanostructured Al₂O₃-40%TiO₂ multiphase ceramic particles were prepared on the surface of 7005 aluminum alloy by plasma spray technology. The microstructure and tribological properties of the composite coatings were researched. The results show that the composite coatings mainly consist of γ-Ni, α-Al₂O₃, γ-Al₂O₃ and rutile-TiO₂ etc, and exhibit lower friction coefficients and wear losses than the Ni-based alloy coatings at different loads and speeds. The composite coating bears low contact stress at 3 N and its wear mechanism is micro-cutting wear. As loads increase to 6-12 N, the contact stress is higher than the elastic limit stress of worn surface, and the wear mechanisms change into multi-plastic deformation wear, micro-brittle fracture wear and abrasive wear. With the increase of speeds, the contact temperature of worn surface increases. The composite coating experiences multi-plastic deformation wear, fatigue wear and adhesive wear.

Key words: nanostructured Al₂O₃-TiO₂ multiphase ceramic particles; Ni-based alloy; composite coating; plasma spray; friction; wear