Synthesis of a silicon carbide from natural raw material in a solar furnace

Abstract

The processes of synthesis of silicon carbide from a natural mineral raw material - diatomite mixed with coke have been studied. The mixture of initial material was placed in a graphite crucible installed on the focal zone of the Large Solar Furnace. High-temperature heating was carried out using a stream of concentrated solar radiation of high density (200-300 W/cm2). The crucible with the sample of the material after irradiation with the concentrated solar radiation was cooled arbitrarily for 30 minutes. The synthesized material contain three phases - silicon carbide β-SiC with cubic crystalline lattice and lattice parameter of 0.436 nm; α-SiC with hexagonal crystalline lattice and lattice parameters of a=0.307 nm and c=1.511nm; and graphite with hexagonal crystalline lattice. The silicon carbide material obtained in a solar furnace in a freshly sintered state showed high refractoriness (up to 1650°C), while the material fired at 1550°C showed a refractoriness up to 1580°C.