Thermal cycling behavior of Sm₂Zr₂O₇ ceramics thermal barrier coatings by APS

The pyrochlore structural ceramic of Sm₂Zr₂O ₇ was synthesized by chemical coprecipitation method. Then the feedstock powder for plasma spraying was prepared by spray drying with proper distribution of particle size about 30-70 μm. The thermal barrier coatings with a topcoat of Sm₂Zr₂O₇ and with a two-layer topcoat of Sm₂Zr₂O₇/YSZ were prepared by atmospheric plasma spraying (APS). The cohesive strength of Sm ₂Zr₂O₇ and Sm₂Zr₂O ₇/YSZ coating presented a value of 15.49 and 23.37 MPa, respectively. Microstructure and phase analyses reveal that plasma spraying of complex Sm₂Zr₂O₇ is accompanied with the formation of the transverse crack networks. The TBCs with topcoat of Sm₂Zr ₂O₇ and Sm₂Zr₂O₇/YSZ performed a thermal cycles of 35 and 60 separately under the test temperature of 1100 °C. The thermally grown oxide at the topcoat-bondcoat interface was also the major factors that lead to the coating failure on thermal cycling at about 1100 °C.