Thermal barrier coating using yttria stabilized zirconia by plasma spray technique

This paper deals with the tribological behavior of thermal barrier coating in engine liner and it also deals with the quality of thermally treated coating. Multi-layer structure formed from top coat and bond coat which was deposited on the same type of steel substrates, in which heat treatments may improve the mechanical properties of materials both substrate and coating and enhance their hard-ness for many cases of ceramics through recrystallization of microstructures. In addition, heat treatments will introduce residual stresses by different thermal contractions and lattice misfits because of microstructural changes that could lead to either premature failure or stress relaxation by new crack formations. Tribological wear properties of differently treated thermal barrier coating was examined to see the net effect of heat treatment on mechanical properties by tribometer with pin on disc mode. Indentation test at surface and cross-section of coatings are examined. The SEM and optical microscope examine several crack propagations. Energy-dispersive X-ray spectroscopyhelps to characterize thermal barrier coating. After thermally treating the sample, an examination of thermal barrier coating the oxide content was increased, sample became convex due to residual compressive stress, roughness reduces, adhesion between topcoat, and bond coat get reduced eventually. In addition to that, the surface gets cracks due to the reduction in hardness from 330 HV to 212 HV.