Mechanical properties of short carbon fiber reinforced ZrB2–SiC ceramic matrix composites

Abstract A ZrB2–20 vol.% SiC based ceramic matrix composite containing 20 vol.% short carbon fibers was top pressed at 2000 °C and 30 MPa for 1 h. The microstructure and mechanical properties of the composite were investigated. The fracture toughness was 6.56 MPa·m1/2, which is 54% higher than that of ZrB2–20 vol.% SiC composite. The toughening mechanisms were fiber debonding, fiber pull-out and crack deflection. Moreover, it was found that a graphitization transition layer between fiber and matrix led to the decreased in flexural strength. The results presented here point to a potential way for improving the fracture toughness of ultra-high temperature ceramics.