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

In this study, Y 2 O 3 coating is used as an interlayer between Al 2 O 3 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 Al 2 O 3 substrate, which is performed using the aerosol method. The interlayer coating, which comprises the Y 2 O 3 phase, is deposited on the Al 2 O 3 substrate using an e-beam evaporator. The crystal structure of the powder that was used to process the coating is identified as cubic Y 2 O 3 . In contrast, the crystal structure of the top-coating layer and interlayer indicates the presence of two kinds of Y 2 O 3 phases, which possess cubic and monoclinic structures. The single Y 2 O 3 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 Y 2 O 3 coating and interlayer, which show a desirable microstructure. The single Y 2 O 3 coating and the Y 2 O 3 coating with an interlayer exhibit similar hardness and elastic modulus values. Nevertheless, the Y 2 O 3 coating with an interlayer exhibits a higher level of adhesion than the single Y 2 O 3 coating, with a value of 14.8 N compared to 10.2 N.