Microstructure of Sm₂Zr₂O₇ thermal barrier coating prepared by atmospheric plasma spraying

Sm₂Zr₂O₇ powder for thermal spraying was synthesized by solid reaction method using Sm₂O₃ and ZrO₂ as raw materials, and Sm₂Zr₂O₇ thermal barrier coatings were prepared by atmospheric plasma spraying. Microstructure and phases of Sm₂Zr₂O₇ powder and thermal barrier coatings were examined by X-ray diffraction (XRD) and scanning electrical microscopy. The binding strength and thermal conductivity of the Sm₂Zr₂O₇ thermal barrier coating were measured by pulling method and laser-flash method, respectively. The results show that Sm₂Zr₂O₇ powder with un-regular particle shape and a compact congregating microstructure are suitable for thermal spraying. No change of phase composition in the Sm₂Zr₂O₇ powder is observed after thermal spraying. The Sm₂Zr₂O₇ thermal barrier coating has a compact microstructure and a higher binding strength between the coating and substrate. The porosity and binding strength of the coating are about 14.31% and 19.8MPa, respectively. The thermal conductivity of Sm₂Zr₂O₇ thermal barrier coating is only 37.6% of that of YSZ thermal barrier coating under the condition of the same porosity.