Optimization of Mechanical Properties and Thermal Shock Resistance of Lapo4/8ysz Thick Composite Coatings Via Plasma Spraying

The aim of current study is to optimize the mechanical properties and thermal shock resistance of plasma-sprayed LaPO 4 /8YSZ coatings with thickness of 1mm based on a modified Vickers indentation method. As the LaPO 4 content increased from 1wt% to 30wt%, the increasing porosity of the composite coatings led to the decrease of bonding strength of the coating from 8.43±0.29 MPa to 6.08±0.12 MPa, while the residual compressive stress and fracture toughness of the coatings exhibited an increased tendency. Although the bonding strength of the LaPO 4 /8YSZ coatings was lower than that of 8YSZ coating (11.49±0.19 MPa), the minimum residual stress of -51.83 MPa for the coating with LaPO 4 content of 1wt% was obtained, further resulting in the maximum thermal cycling lifetime of 5340 cycles during thermal shock resistance at 900°C. Correspondingly, thermal shock resistance of coating was strongly dependent on the microstructure and mechanical properties of LaPO 4 /8YSZ coatings with the addition of nano-LaPO 4 particles