Histology and high-temperature oxidation resistance of molybdenum disilicide coating

The MoSi_2 coating on the Nb-10W alloy was fabricated by pack cementation.The static at 1600℃ and thermal cycling oxidation resistance properties from room temperature to 1600℃ were tested.The formation mechanism,surface and cross-section morphologies of the coating were studied.The results show that the coating is multistructure including MoSi_2 outer layer,two-phase zone with major NbSi_2 and minor Nb_5Si_3,Nb_5Si_3 diffusion inner layer.The structure of the coating represent good high-temperature oxidation resistance and thermal shock resistance.The vacancy zone between the reservior layer and two-phase zone alleviates the heat stress to avoid cracking in the coating.