Silicon carbide synthesis and modeling in a nontransferred arc thermal plasmareactor

Synthesis of ultrafine (submicron size) silicon carbide in a non-transferred arc plasma reactor is investigated. Silica is used as a source of silicon while methane is used as a reductant. A plasma heated reactor is engineered, designed and constructed and a variety of experiments are conducted under different experimental conditions. The plasma torch is operated using a power range of 28-35 kW with both argon and helium as plasma gases. Different molar ratios of silica and methane are used to study the yield of silicon carbide. Other experiments are conducted to confirm the reaction mechanism. Samples of the gaseous and solid species are collected along the length of the reactor to evaluate the kinetics of the reaction. Based upon the experimental results and thermodynamic analysis, a reaction mechanism is proposed. The powder produced in the experiments is analyzed by chemical and physical characterization. The silicon carbide powder produced is mostly in a size range of 0.2-0.4 micron. Models for the heat and mass transfer and reaction kinetics are developed. Mathematical representation of the different steps involved in the synthesis of ultrafine silicon carbide led to an overall model. The model is solved and used to predict the behavior of the system.