3YSZ/LaPO4 composites applied for thermal barrier coatings (TBC) were deposited by an atmospheric plasma spraying (APS) method. The residual stresses and thermal conductivity of 3YSZ/LaPO4 composite coating samples were investigated. The thickness of the APS coating layer on the substrate metal was about 115 to 130 μm. Residual stresses of APS coating samples were observed to be both compressive and tensile. Residual stresses of APS coating samples were changed by the amount of LaPO4. As the amount of LaPO4 increased, the compressive residual stresses of APS coating samples were increased. The differences of the residual stress of APS coating samples were increased from 49.44MPa of 3YSZ/10 vol% LaPO4 to 305.9 MPa of 3YSZ/40 vol% LaPO4. The thermal conductivity of the 3YSZ/LaPO4 composite coating layer was calculated by utilizing APS coating layer on the substrate metal. The calculated value of the thermal conductivity of coating layers ranges from 0.11 to 0.19 W/m·K.

Keywords: YSZ, LaPO4, APS method, residual stress, thermal conductivity.