Microwave heating and mechanism for seed-induced synthesis of SiC

Abstract

We prepared silicon carbide (SiC) through microwave heating using α-SiC particles, coal mineral particles, and tetraethoxysilane as seeds, carbon source, and silicon source, respectively. By characterising the phase and microstructure, the effects of different temperatures, holding time, and seed content on the growth of SiC crystals were studied. β-SiC and α-SiC particles were synthesised through microwave heating at 1100 °C for 10 min. An increasing holding time resulted in higher whisker yield. The crystal generation mode was through a vapor-vapor reaction, in which SiC crystallites formed on the surface of the α-SiC seeds via in situ nucleation and grain growth. The impedance matching between coal minerals and α-SiC seeds varied with the seed content, which also influenced the power redistribution, results in different heating rates, phases, and morphologies during microwave heating. The 15 wt% seed content was identified as the optimal value for both microwave heating effects and power redistribution, which promoted the formation of β-SiC whiskers. These results show that the rapid synthesis of SiC is achieved while coal as carbon source, which will greatly reduce cost to promote the commercialization of SiC via microwave heating.