Mechanism in reactive plasma spraying synthesis of TiC–TiB2 composite coating

Self-propagating high-temperature synthesis reaction in the LaMgAl11O19–Ti–B4C system was quenched in the glove box and during plasma spraying, respectively, in order to clarify the formation mechanism of in situ TiC–TiB2 composite coating. Microstructure of the quenched samples was investigated by X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray spectrometer. The results showed that the formation mechanism of TiC and TiB2 during reactive plasma spraying is same as that in the glove box, namely the Ti–B–C melt is first formed by B4C particles dissolving into the Ti–B eutectic liquid as well as the molten Ti, and then TiC and TiB2 are formed and precipitated from the saturated Ti–B–C melt.