Effect of Interlayer on Flatness and Adhesion of Aerosol-Deposited Yttrium Oxide Coating.

In this study, YO coating is used as an interlayer between AlO substrate and a ceramic coating; this is in order to minimize the morphological distortion produced by a single deposition of the ceramic coating on the AlO substrate, which is performed using the aerosol method. The interlayer coating, which comprises the YO phase, is deposited on the AlO substrate using an e-beam evaporator. The crystal structure of the powder that was used to process the coating is identified as cubic YO. In contrast, the crystal structure of the top-coating layer and interlayer indicates the presence of two kinds of YO phases, which possess cubic and monoclinic structures. The single YO coating without an interlayer exhibits microcracks around the interface between the coating and the substrate, which can be attributed to the stress that occurs during aerosol deposition. In contrast, no cracks are found in the aerosol-deposited YO coating and interlayer, which show a desirable microstructure. The single YO coating and the YO coating with an interlayer exhibit similar hardness and elastic modulus values. Nevertheless, the YO coating with an interlayer exhibits a higher level of adhesion than the single YO coating, with a value of 14.8 N compared to 10.2 N.