Study and Comparison of Boron Oxide Reduction by Silicon and Magnesium for Synthesis of SiC-B4C Nanocomposites by MASHS Method

In this study, boron oxide reduction by silicon and magnesium was investigated and compared for synthesis SiC-B4C nanocomposite. The material in two groups, one consist of silicon, carbon and boron oxide and other magnesium oxide, boron, carbon and silicon were weighed. Weighed powders were milled by planetary mill under argon atmosphere. Pellets were prepared by uniaxial press from milled powder. The pellets were placed in tubal furnace with argon atmosphere control at 1000 °C temperature. For phase study and calculate the average of crystallite size, the samples were analyzed by XRD at any stage of process. The sample with the appropriate synthesis conditions was performed by SEM and TEM analysis. XRD analysis showed the inability of silicon for reduction of boron oxide at this process. These results also indicate success in reduction of boron oxide by magnesium and resulting in the synthesis of silicon carbide-boron carbide composite. Average crystallite size of SiC and B4C for sample with suitable synthesis conditions was calculated 11 and 10 nm respectively. The SEM micrograph indicated the composite consists of submicron sized particles. The image of TEM analysis confirmed the results of average crystallite size calculations and showed the composite composed from grains in nanoscale range.