Analysis of the Mechanical Properties in Short Carbon Fiber-toughened ZrB2-SiC Ultra-high Temperature Ceramic

ZrB2-20 vol.% SiC ceramics with additional 20 vol.% short carbon fibers were developed to promote graceful failure using hot-pressing technique. The influence of short carbon fiber on the strength, and modulus of composite was analyzed and estimated using a modified rule of mixtures. The calculation results showed that a little decrease in flexural strength from 502 to 445MPa and elastic modulus from 414 to 322 GPa was due to the lower elastic modulus of short carbon fiber. An apparent increase in fracture toughness from 2.0 to 6.56 MPa m(1/2) was obtained with the addition of short carbon fiber. And the fracture toughness was analyzed and calculated based on the toughening mechanisms of crack deflection, fiber pullout, and crack bridging. Calculated results were in good agreement with experimental results.