Thermal plasma processing of B/sub 4/C and Al-B/sub 4/C nanopowders

Summary form only given. B/sub 4/C powders are produced commercially in EAF via gas phase reaction or carbothermic reduction. Milling and purification is a necessary step for powders produced by this method. Also, as these powders are difficult to sinter to full density, they need pressurized sintering techniques and dopants to reduce sintering temperatures. In this study, B/sub 4/C powders are synthesized using thermal plasma technology. A non-transferred arc DC thermal plasma reactor is used to produce fine ultrapure B/sub 4/C powders by reaction between B/sub 2/O/sub 3/ powder and CH/sub 4/ gas. Thermodynamic analysis for the reaction systems was carried out based on Gibbs energy minimization. The product powder was characterized using XRD and SEM. Effect of process variables such as boron oxide powder to methane gas ratio, boron oxide feed rate and input power on product recovery and quality were studied. Quantitative XRD analysis was done to calculate B/sub 4/C product yield. B/sub 2/O/sub 3/:CH/sub 4/ molar ratio of 2:7, low B/sub 2/O/sub 3/ feed rate and Higher powder yield better B/sub 4/C powder product.