Thermal Barrier Characteristics of Partially Stabilized Zirconia Coatings on INCOLOY Alloy 909 (A Controlled Expansion Alloy)

Abstract

INCOLOY alloy 909 is a low-expansion alloy used in critical seal and shaft applications within the gas turbine engine. However, because of its poor oxidation resistance at elevated temperatures, the maximum service temperature is limited. Since its coefficient of expansion is similar to that of partially stabilized zirconia for temperatures to 1200°F (649°C), it has been proposed to use this metal-ceramic combination for dimensionally critical, air-cooled jet engine components. This coating system should extend temperature limitations by reducing metal temperatures and providing oxidation resistance. The performance advantage offered by a thermal barrier coating has been investigated at temperatures up to 2000°F (1093°C) and the results are presented in this paper. Metal temperatures and heat flow rates of coated and bare specimens are compared for two air-cooling flow rates.