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

The low-temperature cyclic oxidation resistance of MoSi 2 /19.3 vol% SiC nanocomposite coating formed on a Mo substrate in air at 500°C was investigated and compared with that of the monolithic MoSi 2 coating using field emission-scanning electron microscopy (SEM) and crosssectional 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 MoSi 2 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 SiO 2 and Mo 9 O 2 6 composite oxide scale through the preferential oxidation of SiC particles followed by oxidation of MoSi 2 phase.

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