Thermal barrier coatings have become essential for hot section components in aero and IGT turbine engines, to allow them to run at today's' high temperatures. The thermal barrier coating is considered a system, comprised of the superalloy substrate alloy, a metallic bondcoat and a zirconia-based outer ceramic layer. The zirconia ceramic has relatively low thermal conductivity and thus provides thermal insulation to the substrate. In the engine, the thermal barrier coating system is operated in a temperature gradient, with the zirconia surface exposed to the hot gas side of the turbine section and the substrate alloy of the blade, vane or combustor component typically air cooled on the back side.
Higher operating temperatures for gas turbine engines are continuously sought in order to increase their efficiency. However, as operating temperatures increase, the high temperature durability of the components of the engine must correspondingly increase. For this reason, the use of thermal barrier coatings on components such as combustors, high pressure turbine blades and vanes has increased in commercial as well as military gas turbine engines. The insulation of a thermal barrier coating enables components formed of superalloys and other high temperature materials to survive higher operating temperatures, increases component durability and improves engine reliability.
A need continues to exist for powders and thermal barrier coatings that can be deposited by thermal spray devices and that exhibit excellent thermal shock resistance. Therefore, a need continues to exist for developing new powders and for exploring their potential for thermal spray deposition of thermal shock resistant coatings. It would therefore be desirable in the art to provide powders and thermal barrier coatings that can be deposited by thermal spray devices and that exhibit excellent thermal shock resistance.
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