Microstructure and mechanical properties of newly developed SiC-C/C composites under atmospheric conditions

The purpose of this study is to investigate the relationship between its microstructure and bending strength of SiC-C/C (carbon-carbon) composites. By using the phenolic resin and carbon fiber bundle, the carbon fiber reinforced plastics (CFRP) precursor was prepared by employing filament winding technique. To modify the phenolic resin, the micro-sized glass fiber was added. The CFRP precursor was charred at high temperature at Argon atmosphere to obtain SiC-C/C composites. The matrix of composites was densified by resin impregnation done by cold isostatic pressing (CIP) method. The detail observation of matrix after charred revealed that when precursor resin was modified with glass fiber, the direction of thermal crack at matrix showed complex manner, while thermal crack at un-modified matrix only appeared along fiber direction. Because of the presence of complex thermal crack, the matrix of SiC-C/C composite showed high porosity at un-densified condition and effectively densified by CIP to promoting resin flow toward thermal crack. The bending and compression test results showed that bending strength and inter-laminar shear strength of SiC-C/C composites was increased by densification. Moreover, the fractured surface observations suggested that the presence of synthesized SiC nano-whisker at inter-laminar enhances the apparent shear strength due to mechanical bridging between laminar.