Characterization of a Si-SiO2 mixture generated from SiO and CO

Abstract

The reaction between SiO(g) and CO(g) is a relevant intermediate reaction in the silicon production process. One of the products generated from this gas mixture is called by its color, brown condensate. In this paper, SiO(g) and CO(g) are produced from SiO2-SiC pellets. The reaction between the two gases occurred on SiC particles. Inert gas was injected at different flows. The SiC particles were collected, and the brown condensate deposited on them was characterized by Electron Probe Micro-Analysis (EPMA), X-Ray Photoelectron Spectroscopy (XPS) and Focused Ion Beam (FIB) preparation samples for Transmission Electron Microscope (TEM) analysis. The brown condensate consists of a mixture of Si spheres embedded in a SiO2 matrix. The temperature of formation of the compound is between 1400-1780{degree sign}C (1673-2053 K), dependent on the inert gas flow. SiC crystallites are located at the Si-SiO2 interface. Carbides are believed to generate from the reaction between liquid silicon and CO(g). Carbides may also precipitate from reaction between dissolved carbon and liquid silicon, but to a minor extent. Both mechanisms are believed to happen above the melting point of silicon and in the softening range of silica.