ZrSi2-SiC/SiC Gradient Coating of Micro-Structure and Anti-Oxidation Property on C/C Composites Prepared by SAPS

A ZrSi2-SiC/SiC gradient coating system was designed to reduce the thermal stress of anti-oxidation coatings for C/C composites and prolong their time at a high temperature. The SiC transition layer prepared by pack cementation ZrSi2-SiC outer with different ZrSi2 contents added were deposited supersonic air plasma spraying (SAPS). micro-morphologies phase compositions studied SEM, EDS, XRD, TG/DSC, performances tested static oxidation experiment. findings suggested that 30 wt.% content displayed optimum dense microstructure without obvious pores microcracks, compared other three proportional coatings. During test, because reaction phases, large amount silica formed in fill microcracks densify further. Oxidation products ZrO2 ZrSiO4, having melting point outstanding property, embedded SiO2 glass volatilization rate improve ability block oxygen. Therefore, specimen still kept mass gain after 188 h 1500 °C. However, when increased 198 h, it had loss 0.1%, compactness destroyed escape gases.