Mechanical properties of ceramic composites

Silicon-nitride-based ceramic materials are strong candidates for structural applications, such as cutting tools, considering their high thermal and mechanical properties. However, such materials can suffer catastrophic failures, because they are very sensitive to flaws. In this work, silicon-nitride-based matrix was reinforced with silicon carbide whiskers, aiming to increase fracture toughness. Monolithic silicon nitride samples were also produced. All compositions were pressureless and hot uniaxial pressed, followed by physical and mechanical properties determination. Fracture toughness of composites showed higher fracture toughness values than those from monolithic materials, probably by the activation of crack and crack-bridging mechanisms.