A Study of Several Oxidation-Resistant Coatings on Mo-0.5Ti Alloy Sheet at 2,500 degrees F

Abstract : The results are presented of a study of several silicide-base oxidation-resistant coatings applied to 0.012-inch-thick molybdenum-alloy sheet. The specimens were both continuously and cyclically exposed at 2,500 degrees F in air. The effect of three different types of thermal cycles was investigated. A failure mechanism is proposed to explain the severe reduction observed in the ability of a coating to protect the substrate when thermally cycled. A failure mechanism for the continuously exposed coated specimens is also proposed. The investigation includes the results of X-ray studies and room-temperature mechanical-property tests on the coated specimens.