Properties of the BaTiO3 coating prepared by supersonic plasma spraying

•BaTiO3 coatings were successfully sprayed by employing the HEPJet spraying system.•The average bond strength between the coating and substance was 42MPa.•The coating exhibits the piezoelectric with different frequencies at room temperature. Plasma spraying technique enables to create layers with thickness in a millimeter range adhering to various substrates. The supersonic plasma spraying can spray the powders at acoustic speed, which can increase the coating density and improve the bond strength between the coating and substrate. In the present study, a BaTiO3 coating with good physical property and preliminary piezoelectric index was prepared by supersonic plasma spraying. The spraying process was carried out by a direct current gas-stabilized plasma gun, which was manufactured by the Science and Technology on Remanufacturing Laboratory. It was found that the high temperature could make the BaTiO3 possess the piezoelectric nature. The surface of the BaTiO3 coating was smooth and dense, and the mechanical bond existed between the substrate and the coating. The average bond strength and microhardness were 47.4MPa and 650HV0.1, respectively. The BaTiO3 phase changed from cubic to tetragonal phase in the course of supersonic plasma flame flow. About 25% (mol) BaTiO3 was decomposed into BaO and TiO2. The decomposition and original defects of the spraying coating could decrease its piezoelectric activity. The piezoelectric performance of the BaTiO3 coating was lower than that of the sintering ceramic, but obvious piezoelectricity existed in the sprayed BaTiO3 coating.