Transformation of β-SiC from Charcoal, Coal, and Petroleum Coke to α-SiC at Higher Temperatures
Sethulakshmy Jayakumari, Merete Tangstad
Abstract
Abstract SiC is one of the main intermediate compounds formed during the industrial production of silicon (Si). In the Si process, SiC is produced when carbon added to the raw materials reacts with the silicon monoxide gas (SiO(g)) formed in the furnace. Carbon materials used are either biomass-based (charcoal and wood chips) or based on fossil sources (coal, coke, petroleum coke). The most common forms of SiC prevailing at atmospheric pressure are the polytypes of α -SiC and β -SiC. β -SiC is formed at low temperatures and transforms to α -SiC at higher temperatures (> 2000 °C). In this study, β -SiC with elemental Si of varying amounts, formed from industrial carbon materials (charcoal, coal, and petroleum coke), were utilized to study the transformation of β -SiC to α -SiC. A graphite tube furnace efficient for high-temperature experiments was utilized for the heat treatment of β -SiC particles at temperatures ranging from 2100 °C to 2450 °C. The transformation to α -SiC was greatly influenced by the original carbon source. Charcoal-converted β -SiC particles easily transformed to α -SiC at 2100 °C, compared with β -SiC produced from coal and petroleum coke. Moreover, the amount of elemental Si in SiC particles enhanced the transformation to α -SiC at 2100 °C.