Synthesis of well-dispersed columnar Si3N4 using carbothermal reduction–nitridation method

Abstract

Si3N4 has attracted much attention as the thermally conductive fillers owing to its high thermal conductivity, high electrical resistivity and low dielectric loss. This paper presented the preparation of well-dispersed columnar Si3N4 particles by carbothermal reduction–nitridation (CRN) strategy with assistance of unique CaF2 additive under an elevated N2 pressure. The average diameter of columnar particles was 4 μm and aspect ratio was 3. The speculation for the inherent growth mechanism of the Si3N4 particles was tentatively proposed. It was speculated that CaF2 could promote the formation of β-Si3N4 with columnar structure through a V-L-S (vapor-liquid-solid) route by forming Ca-containing liquid phase with SiO2. Moreover, appropriate content of CaF2 are beneficial for fabricating Si3N4 particles with good dispersity because of the proper the evaporation rate of Ca and F.