Nextel 720/silica composites by metal organic chemical vapor infiltration

The development of non-oxide ceramic matrix composite has resulted in composites with suitable property for certain structural application, but they all retain susceptible to long term degradation after high temperature exposure to oxidizing environments. Continuous oxide fibers reinforced oxide matrix composites are attractive for use as high temperature structural materials because they can combine composite properties with long-term oxidative stability. In this paper, the processing of Nextel 720/silica composites by MOCVI (metal organic chemical vapor infiltration) at atmosphere pressure is described. TEOS (Tetraethylorthosilicate) was used as precursor. The effects of concentration of O₂, flux of carrier, temperature of TEOS and deposition temperature on deposition rate of silica and Nextel 720/silica microstructure were studied with lots of experiments. The results exhibit the optimal conditions for MOCVI are TEOS temperature 60°C , deposition temperature 600°C , flow rates of Ar and O₂ 400 ml· min^-1 and 30 ml·min^-1 respectively.