Effects of Diamond on the Mechanical Properties and Thermal Conductivity of Si3N4 Composites Fabricated Using Spark Plasma Sintering
摘要
Micrometer-sized diamonds were incorporated into silicon nitride (Si3N4) matrix to manufacture high-performance Si3N4-based composites using spark plasma sintering at 1 500 °C under 50 MPa. The effects of the diamond content on the phase composition, microstructure, mechanical properties and thermal conductivity of the composites were investigated. The results showed that the addition of diamond could effectively improve the hardness of the material. The thermal conductivity of Si3N4 increased to 52.97 W/m·k at the maximum with the addition of 15 wt% diamond, which was 27.5% higher than that of the monolithic Si3N4. At this point, the fracture toughness was 7.54 MPa·m1/2. Due to the addition of diamond, the composite material generated a new substance, MgSiN2, which effectively combined Si3N4 with diamond. MgSiN2 might improve the hardness and thermal conductivity of the materials.