SiC/MoSi2 based coatings for Cf/C composites by two step pack cementation

In order to improve the oxidation resistance of Cf/Cs produced by chemical vapour infiltration, a multilayer coating based on silicon carbide and molybdenum disilicide was produced by two-step pack cementation technique. The inner SiC layer with a thickness up to 25 μm was obtained without promoted reaction additives by varying the composition, and thermal treatment conditions. The SiC/SiC-MoSi2 coating was produced with a thickness up to 80 μm by two step pack cementation, considering the effect of the inner layer characteristic. The enhancement of the oxidation resistance, observed in SiC/SiC-MoSi2 coated Cf/Cs by means of thermal analysis in flowing air up to 1500 °C, was due to the formation of SiO2 promoted by the passive oxidation of silicon carbide and molybdenum disilicide.