In situ synthesis, microstructure and mechanical properties of nano-structured SiC-ZrC composite prepared by spark plasma sintering

The synthesis route, microstructure and mechanical properties of SiC-ZrC composites prepared from a mixture of ZrSi2-C powders by reactive spark plasma sintering (R-SPS) were investigated. The reaction between ZrSi2 and C began to occur at 550 °C and mostly completed at 1300 °C. On the other hand, the densification during SPS occurred mainly between 1490 °C and 1750 °C, indicating that the reaction did not directly promote the densification. A fully dense SiC-ZrC composite (relative density > 99%), in which fine SiC (∼260 nm) and ZrC (∼360 nm) grains distributed homogeneously, was prepared by SPS at 1750 °C under a pressure of 40 MPa. The formation of nano-composites can be ascribed to the high energy ball milling of raw materials, fine ZrC and SiC grains formed during R-SPS, and low sintering temperature by R-SPS process. The Vickers hardness, fracture toughness and Young's modulus of the composite were 23.3 GPa, 2.87 MPam1/2, and 319 GPa, respectively. [Display omitted] •SiC-ZrC composites without any sintering additives were prepared from ZrSi2-C by reactive spark plasma sintering.•The in situ reaction mechanism of SiC-ZrC composites was investigated.•Fully dense SiC-ZrC with ultra-fine and homogeneous microstructure were obtained at a low sintering temperature of 1750 °C.•The material can be used for the hyper-sonic transportation and next generation fusion-fission technology.