Recycling of silicon kerf loss derived from diamond-wire saw cutting process to prepare silicon nitride

In this paper, silicon kerf loss derived from diamond-wire saw cutting process was recycled to synthesize Si3N4 powders and ceramics via the incorporation of carbothermal nitridation and direct nitridation. The effects of sintering temperatures and CaO additives on the nitridation behavior were studied in detail. The results showed that the main impurities were SiC and Si2N2O in Si3N4 powders products, and the content of impurities could be reduced with the increasing of sintering temperatures and CaO additives. In addition, the acceleration mechanisms of sintering temperatures and CaO additives on the nitridation were investigated and proposed by the thermodynamics calculation and density functional theory, respectively. Owing to the acceleration effect of CaO additives on the nitridation, the properties of the obtained Si3N4 ceramics were obviously improved. When the content of CaO additives was 5 wt%, the as-prepared Si3N4 ceramic had a bulk density of 2.31 g cm−3, apparent porosity of 25.42% and a compressive strength of 109 Mpa. In a word, this study presented a feasible approach for recycling silicon kerf loss to fabricate high-value Si3N4 materials, which could be applied to other harmful waste resources.