Residual stress and fracture toughness of thick 8YSZ-Al2O3 composite coatings via a modified Vickers indentation method

The aim of current study is to explore a modified Vickers indentation method for characterization of the residual stress and fracture toughness of thick 8YSZ-Al2O3 composite coatings. According to the results, the through thickness residual stress of coating with thickness of 870 μm increased from −114.7 MPa to −368.3 MPa as the Al2O3 content varied from 10 wt% to 40 wt%, which was higher than that with thickness of 590 μm. It was revealed that the increase of Al2O3 content and coating thickness resulted in accumulation of the compressive residual stress in these thick composite coatings. Simultaneously, the fracture toughness of coatings with different thicknesses also exhibited an increasing tendency with the increase of Al2O3 content.