Effect of Critical Plasma Spray Parameters on Microstructure and Mechanical Properties of Plasma-Sprayed YSZ-20 wt%LSM Composite Coating

The effect of critical plasma spray parameters (CPSP) on the phase composition, microstructure and mechanical properties of a plasma-sprayed YSZ-20 wt%LSM coating was investigated. With the CPSP value ranging from 0.83 to 1.17, the average porosity of the composite coating was gradually reduced from 19.22 ± 0.72 to 11.95 ± 0.32%, resulting in the improvement of bonding strength from 9.1 ± 0.26 to 11.58 ± 0.15 MPa. Relatively, due to the decrease of the porosity of coating, the compressive residual stress was augmented from − 66.13 ± 2.23 to − 128.69 ± 2.02 MPa with the CPSP value increasing from 0.94 to 1.17, while the corresponding fracture toughness was slightly decreased, from 2.11 ± 0.09 to 1.15 ± 0.11 MPa m ½ . As a result, an apparent change in the mechanical properties of the coating was mainly attributed to the adjustment of the porosity of the coating controlled by the CPSP value, which was beneficial for the modification of the service reliability of the composite coating with a thickness of about 1 mm.