Effects of random chopped short carbon fibers on microstructure and mechanical properties of joints for Cf/SiC composites by reaction bonding process

Random chopped short carbon fibers (Csf)/phenol-formaldehyde resin (PF)/SiC powder mixtures are used as filler for the joining of Cf/SiC composites to obtain SiC interlayer at the joining region. The influences of Csf on the microstructure and mechanical properties have been investigated. Research shows that the introduction of Csf can improve the microstructure uniformity of the joint and reduce residual silicon content in the interlayer. The joint achieve a high flexural strength of 232 ± 33 MPa as the carbon fiber content is 30 wt.%, which is similar to that of the Cf/SiC composites (220 ± 21 MPa). The decrease in residual silicon content and the formation of nano-sized SiC particles are the main reasons for high joining strength.