Microstructure evolution during reactive plasma spraying of MoSi2 with methane

The mechanisms that govern microstructure evolution during reactive plasma spraying of MoSiz using 100% methane were investigated, with particular emphasis on the thermodynamics and kinetics of the relevant phase transformations and chemical reactions. The reactive plasma-sprayed M0Si₂ exhibited a dense, multilayered microstructure. In addition to the M0Si₂ matrix, significant amounts of M0₅Si₃ and elemental carbon were observed, along with a small amount of SiC. Thermodynamic and kinetic analysis predicted a large volume fraction of M0₅Si₃ and a small amount of SiC in the as-deposited reactive plasma-sprayed MoSi₂, in agreement with the experimental observations.