Effects and function mechanism of Fe‐containing additives on SiC synthesis with silicon cutting waste

Abstract

With the rapid development of the photovoltaic industry, a great amount of silicon cutting waste (SCW) are being generated, which lead to a heavy environmental burden as well as a high cost of the photovoltaic industry. In this paper, the effects of Fe-containing additives and their function mechanism on recycling SCW to synthesize high-purity SiC were studied. The results show that Fecontaining additives, including Fe, Fe 2 O 3 , and Fe(NO 3 ) 3 , have obvious effect on recycling SCW to synthesize SiC. And Fe(NO 3 ) 3 additive achieves the best effect.Fe(NO 3 ) 3 can effectively destroy the SiO 2 film wrapped on the Si particles, so that expose the inner Si to C at lower temperatures than that of the reaction between C and SiO 2 . Besides, Fe(NO 3 ) 3 additive can effectively reduce the activation energy both for Si and C reactions and SiO 2 and C reactions, and contribute to the transport of the raw materials as well as the dissolution and precipitation of Si and C due to the formation of the FeSi melt at low temperatures. The optimal processing conditions are determined as Fe(NO 3 ) 3 addition of 1-3 wt.% and smelting temperature of 1200-1300°C.