A Comparison of Sol-Gel Derived Silicon Carbide Powders from Saccharose and Activated Carbon

摘要

β-SiC has been synthetised at 1550℃ by the reductive heating of gel precursors prepared from silica sol and saccharose or activated carbon as carbon sources. An optimum molar ratio of reactants, C/SiO_2, as well as the mechanism of SiC crystallization, have been investigated for each carbon source applied. The influence of boric acid addition in the starting sol on the properties of SiC powders produced has been elaborated. Boric acid represents a catalyst for the carbothermal reduction of silica within the established range of concentrations which is, in return, dictated by the molar ratio of reactants and carbon source in the system.