LAUSR

Abstract Silicon nitride (Si 3 N 4 ) based composites have been extensively studied and widely used in industrial applications. Herein, SiC/Si 3 N 4 composites were prepared through hot press sintering at 1700 °C under nitrogen (N 2 ) atmosphere. Fluoride additives (AlF 3 and MgF 2 ) were used to reduce lattice oxygen content, which can affect the bulk density and a source to increase the porosity of the composite. Experimental results revealed that the chemical compatibility between silicon carbide (SiC) and Si 3 N 4 matrix under high temperature sintering could be effectively improved by integrating SiC/Si 3 N 4 ceramics interphase. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) results indicate that a complete transformation of α to β-Si 3 N 4 and intergranular behavior of material occurred, which revealed that the phase transformation was unaffected by the addition of SiC. Furthermore, the enhanced crystallization degree and a strong interfacial effect of the SiC/Si 3 N 4 composites enabled to obtain a significant increase in thermal conductivity (90.67–145.66 W/mK), fracture toughness (8.52–10.3 MPa m 0.5 ) and Vickers hardness (1849–2125 HV).