Phase composition and microstructure of yttrium aluminum garnet (YAG) coatings prepared by suspension plasma spraying of Y2O3-Al2O3 powders

Yttrium aluminum garnet (Y3Al5O12, YAG) is a promising high-temperature ceramic. YAG coating was deposited using the suspension plasma spraying process. The phase composition, microstructure, and hardness properties of the as-deposited coatings were investigated. X-ray diffraction analysis confirmed that YAG is the major phase with a small amount of YAP and YAM phase. SEM characterize results indicate that high power and short standoff distance will result in a compact coating with high hardness and low porosity, and with the Vickers hardness of 739HV. On the contrary, increasing standoff distance and decreasing torch power will lead to form more re-solidify spherical particles and unmelted powder, respectively.