Sm₂Zr₂O₇ thermal barrier coatings prepared by high energy plasma spraying and its property of thermal shocking

Sm₂Zr₂O₇ thermal barrier coatings were prepared by high energy plasma spraying technology, Phase and microstructure of the coatings were studied by X-ray diffraction (XRD) and scanning electron microscope (SEM). Bonding strength and thermal shocking property of the coatings were investigated by pulling test and water quenching method, respectively. Results show that there is no change of phase of Sm₂Zr₂O₇ powders after thermal spraying, which shows better phase stability. The coatings have a compact microstructure and the interface bind tightly between Sm₂Zr₂O₇ coating, NiCoCrAlY bonding layer and subtrate are obtained. Porosity in the coatings is about 4.72%. Its bonding strength is 29 MPa which is higher than that of Sm₂Zr₂O₇ thermal barrier coating prepared by atmospheric plasma spraying. This coating spalls at the interface between the top Sm₂Zr₂O₇ layer and NiCoCrAlY metal bonding layer after twenty thermal cycles. The lognitudinal micro-carcks melted powder particles and transverse cracks formed by seperation of the melted particles lead to the spalling of the coatings.