THE SIZING AND HIPPING EFFECTS ON THE PROPERTIES OF 3D C/C COMPOSITES

The sizing treatment of carbon fiber has a great effect on the properties of 3D C/C composites. Sizing agents that can form a good interlayer are preferred. The quality of the interlayers determine the properties of C/C composites. Furfuryl alcohol-maleic-anhydride-ethylene-glycol resin is found to be one of the best sizing agents. This is due to its ability to form a firm layer to protect fiber from attack by a matrix precursor. Hipping is the best way to density the carbon weaving preform and to control the microstructure of matrix. Higher HIP pressure may produce more random matrix structure. The densification efficiency, e, which has been formulated from the experimental results in this work, can be used to predict the density of C/C after a given densification cycle. The combined effects of sizing and hipping improve the mechanical properties of 30 C/C composites, in particular the in toughness and flexural strength. An almost two-fold flexural strength has been obtained by this process.