The production of boron carbide by carbothermic reduction

Carbothermic reduction of boric acid has scientific and economic advantages over other methods of boron carbide production. The strongly endothermic reaction which has a favourable free energy change only at high temperatures is best carried out in a specially designed graphite resistance furnace at temperatures above 2000 degrees C, using boric acid and petroleum coke as starting materials. The composition of the charge has a strong influence on the quality of boron carbide obtained and also on the yield. The use of boron anhydride in place of boric acid decreases the yield. The yield is also affected by the heating conditions prevailing in the furnace. The yield of boron carbide can be substantially improved and thus the specific energy consumption in boron carbide production can be significantly decreased by adding an optimum quantity of salt to the boric acid-petroleum coke mixture. The various factors that influence the quality and yield of boron carbide product and hence the economy of boron carbide production by the carbothermic reduction route have been discussed in this paper.