Preparation & characterization of SiO₂ interface layer by dip coating technique on carbon fibre for C_f/SiC composites

Carbon fibres (C_f) are one of the most important reinforced materials for ceramic matrix composites such as C_f - SiC composites and they are generally sought for high temperature applications in as space application, nuclear reactor and automobile industries. But the major problem arise when C_f reinforced composites exposed to high temperature in an oxidizing environment, C_f react with oxygen and burnt away. In present work, we have studied the effect of silica (SiO₂) coating as a protective coating on C_f for the C_f / SiC composites. The silica solution prepared by the sol-gel process and coating on C_f is done by dip coating technique with varying the withdrawing speed i.e. 2, 5, 8 mm/s with fixed dipping cycle (3 Nos.). The uniform silica coating on the C_f is shown by the Scanning Electron Microscope (SEM) analysis. The tensile test shows the increase in tensile strength with respect to increase in withdrawing speed. The isothermal oxidation analysis confirmed enhancement of oxidation resistance of silica coated C_f as compared tothe uncoated C_f.