Abstract:In this experiment, hafnium oxide powder was prepared by spray drying-high temperature sintering method and hafnium oxide coating was prepared on the surface of steel substrate by atmospheric plasma spraying (APS). The effects of sintering temperature on the microstructure and properties of hafnium oxide powder and coating were studied. The results showed that as the sintering temperature increased from 1000 ℃ to 1300 ℃ , the microstructure of hafnium oxide powder didn't changed significantly, and the micro-particles didn't grow up obviously. When the sintering temperature reached 1400 ℃ or higher, the micro-particles began to be micro-melted and connected with network-like framework. When the sintering temperature was between 1000 ℃ to 1300 ℃ , the strength of powder particles was relatively low. With the sintering temperature raised to 1400 ℃ and 1500 ℃ , the strength of powder particles gradually increased. The structure of coating prepared by hafnium oxide powder after 1400 ℃ sintering treatment was uniform and relatively dense. The porosity of hafnium oxide coating was 3.9%, the average microhardness of the coating was 552.24 HV0.3. The average bonding strength of the coating reached 24.78 MPa.