Improving mechanical properties of continuous carbon fiber-reinforced ZrB2-ZrSi2 composite by addition of activated carbon

Continuous carbon fiber-reinforced ZrB2-based composites have great potential in the application for ultra-high temperature structural components. However, carbon fiber is prone to serious interfacial reaction with low-melting point phases during the high-temperature preparation process, which not only cause fiber damage but also limit fiber toughening effect. In the current work, activated carbon was introduced into the composite to modulate the microstructure and fiber–matrix interface. Results indicated that activated carbon can act as a sacrificial agent to inhibit the chemical raction between carbon fibers and ZrSi2 and convert the low-melting-point phases into high-temperature-resistant phases. Fiber degradation and interfacial reaction were effectively reduced. As a result, mechanical properties of the composite were significantly improved. The flexural strength, fracture toughness and work of fracture of the composite was 200 MPa, 7.07 MPa·m1/2 and 1669 J·m−2, which were 94 %, 58 % and 158 % higher than that of the composite without added activated carbon, respectively.