Microstructure And Mechanical Properties Of Plasma-Sprayed Lamga111o19 Thick Ceramic Coatings

In the research, the effect of different critical plasma spray parameters (CPSP) on the microstructure and mechanical properties of plasma-sprayed LMA coatings with thickness of 797 mu m were investigated. As a result, the porosity of coatings was increased from 12.14% to 24.88% with the decrease of CPSP from 1.20 to 0.86, while bonding strength of coatings was obviously reduced from 15.98 +/- 0.36 MPa to 4.87 +/- 0.7 MPa. Relatively, Young's modulus and hardness of the coatings exhibited a decreasing tendency with the decrease of CPSP. When the CPSP was decreased from 1.20 to 0.97, the residual compressive stress of coating surface varied from -162.10 +/- 12.13 MPa to -93.49 +/- 3.28 MPa, and that obtained from cross-section was decreased from -116.02 +/- 5.92 MPa to -70.68 +/- 3.99 MPa. Meanwhile, the fracture toughness of coating was improved from 0.62 +/- 0.05MPam1/2 to 1.34 +/- 0.05 MPam1/2, which was higher than that of cross-section of coating. The microstructure and mechanical properties of LMA thick coatings were strongly dependent on the CPSP.