Mechanism of improving the mechanical properties of Si ₃ N ₄ /TiC ceramic tool materials prepared by spark plasma sintering

Abstract Spark plasma sintering (SPS) is a new sintering method having shorter sintering time and higher densification speed than the traditional sintering methods. In this paper, the Si ₃ N ₄ /TiC ceramic tool material is sintered by SPS. The microstructure and mechanical properties of the material under different sintering parameters are compared. The sintering process of the material is then analyzed, and the best sintering parameters are obtained. Heat the material to 1600°C and keep the temperature for 15 min, then continue to heat to 1700°C and keep the temperature for 10 min, Si ₃ N ₄ /TiC ceramic tool material has high mechanical properties, its bending strength, fracture toughness, and Vickers hardness are 959 MPa, 8.61 MPa·m ^1/2 , and 15.21 GPa, respectively. The scanning electron microscope (SEM) analysis shows that under this condition, the sintering additives and Si ₃ N ₄ /TiC material form the liquid phase, which makes the Si ₃ N ₄ particles rearrange, dissolve, precipitate, and transform into rod shape β‐Si ₃ N ₄ . In addition, under the action of pulse current and external pressure, electric sparks are generated between TiC particles, which allows the material transfer and particle refinement. Therefore, the β‐Si ₃ N ₄ has uniform grain size, and it is vertically and horizontally arranged in the structure, which makes the material have excellent mechanical properties.