Low-temperature cyclic oxidation behavior of MoSi2/SiC nanocomposite coating formed on mo substrate

Abstract

The low-temperature cyclic oxidation resistance of MoSi2/19.3 vol% SiC nanocomposite coating formed on a Mo substrate in air at 500degreesC was investigated and compared with that of the monolithic MoSi2 coating using field emission-scanning electron microscopy (SEM) and cross-sectional transmission electron microscopy (XTEM). The nanocomposite coating was produced by a prior carburizing process followed by chemical vapor deposition of Si on a Mo substrate. While the accelerated oxidation behavior was observed for the monolithic MoSi2 coating after the incubation time of about 454 cycles, no pest oxidation was observed in the nanocomposite coating. The excellent low-temperature cyclic oxidation resistance of nanocomposite coating resulted from the deceleration of further inward diffusion of oxygen by formation of relatively dense SiO2 and Mo9O26 composite oxide scale through the preferential oxidation of SiC particles followed by oxidation of MoSi2 phase.