Plasma sprayed α-Al2O3 main phase coating using γ-Al2O3 powders

Although alpha-Al2O3 is commonly used as crude materials for preparing Al2O3 coating by plasma spraying, the obtained coatings are mainly made up of gamma-Al2O3 crystalline phase with relatively poor mechanical performance. In this research, we employed an unconventional way, i.e. adopting low-cost gamma-Al2O3 powders as crude material via the optimisation of plasma spraying process to prepare a novel aluminium oxide coating containing alpha-Al2O3 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 similar to 2.5 mu m), consequently having a great potential for exploration and application.