Yttrium Aluminum Garnet Powder Feedstock for Atmospheric Plasma Spray

Abstract

High demands for higher turbine efficiency bring attention to newer and more advanced insulating materials for the high temperature components in the turbine. Yttrium aluminum garnet (YAG) has shown good insulating properties in the previous published research, such as higher temperature limitation and better resistance to calcium–magnesium–alumina–silicate environmental contaminant penetration than the more conventional yttria-stabilized zirconia systems. Whereas in literature, coatings of YAG are typically prepared by solution deposition processes, in the present work YAG powder has been prepared for more conventional thermal spraying methods. The goal is to show the potential YAG powders have as a thermal barrier coating. Different approaches for obtaining a successful deposition and a good coating have been explored. Small-sized industrial-supplied powder and larger in-house-made powder have been compared, emphasizing the importance of energy used for deposition and crystallinity in the final coating. Highly crystalline material has successfully been produced with F4 atmospheric plasma spray system without post-treatment or substrate heating.