Development of a Commercial Process for the Production of Silicon Carbide Fibrils

Phase I of this project demonstrated a new technology for silicon carbide fibril growth that would remove some of the previous impediments to the scale-up to a commercial fibril process. The microwave energy approach was designed to heat only the fibril growth balls, reducing the MTS reaction gas quantities needed to feed the fibril growth process. The continuation of this process development can significantly reduce the fibril growth time and the consumption of expensive raw material gases; therefore, decreasing the future commercial price of the fibril product. The previous Carborundum work concluded with a fibril growth rate of approximately 0.17 millimeters per hour. The Phase I microwave growth process experiments resulted in 0.75 millimeters per hour growth rate. Therefore, the new technology achieved a factor of five increase in growth rate, with minimal optimization work. The near stoichiometric use of raw materials and the increase in fibril growth rate, makes it feasible to attain a volume production price for fibrils of less than $300 per pound, using the microwave process. Phase II (FY 2002) investigates growth process parameters and optimization of those parameters. A pilot line semi-continuous microwave furnace and reaction gas control equipment are designed and fabricated to provide more accurate process operation and data acquisition functions to allow potential commercial scale-up of the process. Experimental work optimizes the fibril growth reaction in the pilot equipment. Materials analysis of the fibril product with electron microscopy is used to characterize and improve the silicon carbide fibril product, during the pilot line development. Oak Ridge National Laboratory’s capabilities will be used to evaluate mechanical and thermal stability properties of the fibrils, to complete the 2002 work. Phase II will conclude with a reasonable definition of the future production process, an approximate specification of the silicon carbide fibril product, and an estimate of the volume fibril price.