MICROSTRUCTURE EVOLUTION DURING REACTIVE PLASMA SPRAYING OF MOSI2 WITH METHANE

The mechanisms that govern microstructure evolution during reactive plasma spraying of MoSi2 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 MoSi2 exhibited a dense, multilayered microstructure. In addition to the MoSi2 matrix, significant amounts of Mo5Si3 and elemental carbon were observed, along with a small amount of SiC. Thermodynamic and kinetic analysis predicted a large volume fraction of Mo5Si3 and a small amount of SiC in the as-deposited reactive plasma-sprayed MoSi2, in agreement with the experimental observations.