Influence of coating on the properties of 3-D carbon fiber braid/Al₂O₃ ceramic composite

The sol dipping and in-situ decomposition method was used to prepare 3-D carbon fiber braid/coating/Al₂O₃ ceramic composite, SiO₂, SiC coating/3-D carbon fiber braid as origin. The Influence of coating on oxidation resistance of CF braid, the mechanical properties and fracture mechanism of composite were characterized by isothermal oxidation weigh-loss, XRD, SEM, electronic tensile, etc. The results showed that the oxidation resistance of CF braid could be noticeably improved, and the interfacial bonding properties of fiber with ceramic were markedly improved by gradient coating, the mechanical properties of composites were also greatly improved (5-10 times), and the fracture model was changed, compared with composite without coating. Pulling-out and bridging of fiber and crack deflection induced by fiber were the fracture mechanism of composites.