Plasma sprayed α-Al ₂ O ₃ main phase coating using γ-Al ₂ O ₃ powders

Although α-Al ₂ O ₃ is commonly used as crude materials for preparing Al ₂ O ₃ coating by plasma spraying, the obtained coatings are mainly made up of γ-Al ₂ O ₃ crystalline phase with relatively poor mechanical performance. In this research, we employed an unconventional way, i.e. adopting low-cost γ-Al ₂ O ₃ powders as crude material via the optimisation of plasma spraying process to prepare a novel aluminium oxide coating containing α-Al ₂ O ₃ crystals with excellent mechanical properties as main phase, and the microstructure, microhardness and tribological properties of the coating were characterised and analysed. The results indicated that the aluminium oxide coating possesses favourable toughness, strength and wear resistance (e.g. HV602.4 and wear loss ∼2.5 μm), consequently having a great potential for exploration and application.