Optical reflector for reducing radiation heat transfer to hot engine parts

Abstract

A high temperature gas turbine component for use in the gas flow path that comprises a specular optical reflector coating system. A thin specular optical reflector coating system is applied to the gas flow path of the component, that is, the surface of the component that forms a boundary for hot combustion gases. The component typically includes a thermal barrier coating overlying the high temperature metallic component that permits the component to operate at elevated temperatures. The thermal barrier coating must be polished in order to provide a surface that can suitably reflect the radiation into the gas flow path. The thin reflector coating system comprises a thin high temperature and corrosion resistant refractory stabilizing layer, which is applied over a thin reflective metal layer, which is applied over a thin high temperature and corrosion resistant refractory sealing layer. The coating system is applied over the polished thermal barrier coating by a process that can adequately adhere the reflector to the polished surface without increasing the roughness of the surface. The coating system reflects radiation back into the hot gas flow path or into the atmosphere. The reflected radiation is not focused onto any other hardware component. The design of the component is such that the radiation is returned to the gas flow path or sent to the atmosphere rather than absorbed into a component that only serves to increase the temperature of such a component.