Effect of the open porosity on the flexural strength of 2-D woven carbon fiber reinforced SiC/C matrix composites by reaction-bonding

Plane woven fabric carbon fiber-reinforced SiC/C matrix composites were fabricated by the reaction-bonding method with phenolic resin and silicon powder. Densification of the composites was accomplished by the impregnation and pyrolysis of phenolic resin. The influence of the open porosity of the SiC/C matrix composites on the flexural strength was compared with that of the C matrix composites fabricated with phenolic resin and graphite powder. The effect of the open porosity on the flexural strength was different between SiC/C and C matrix. The flexural strength of SiC/C matrix composites with an open porosity of approximately 15 percent was approximately 300 MPa; however, that of C matrix composites with an open porosity of approximately 12 percent was only approximately 240 MPa. Also, the mechanical properties of SiC/C matrix composites depended significantly on the heat treatment temperatures before impregnation of phenolic resin. (Author)