The impact of Si3N4 incorporation on the mechanical characteristics of ZrB2–SiC nanocomposite sintered via pressureless method

Due to their unique properties, ultra-high-temperature ceramics possess have great potential for aerospace and industrial applications. In this study, we utilized ZrB2 and Si3N4 powders in micron scale, along with SiC powder in both nano and micron scale. A nanocomposite comprising ZrB2-20Vol% SiC (15% nano - 5% micron)-10 % ZrC was incorporated into the base composition by adding Si3N4 in volumes of 1-2-3 volume and 4%. The process is carried out by pressure-less sintering at 2150◦C. The evaluation in this study involved X-ray diffraction (XRD) analysis, hardness measurement, density determination, fracture toughness assessment, and bending test. The results showed that addition of Si3N4 enhances the relative density, hardness, and fracture toughness of this nanocomposite. The sample with Si3N4volume fraction of 3% has the best performance, with a relative density of 99.4%, a hardness of 20.33 GPa, and a fracture toughness of 3.12 MPa.M1/2.