Synthesis of boron carbide powder by a carbothermic reduction method

Carbothermic reduction process is an economic method to produce boron carbide powder. In the present article this method was utilized to produce a boron carbide powder using commercial purity raw materials. Boric acid as a source of boron, and carbon active and petroleum coke as reducing agents were used. Mixtures of boric acid and carbon bearing material with a particle size of less than 44 μm were placed in a graphite crucible and heated under a flow of argon atmosphere in a tube furnace to 1400–1550 °C for 1–5 h. This resulted in the formation of boron carbide powder with or without un-reacted starting raw materials. It was found that the optimum weight ratio of boric acid to carbon bearing material was 3.5 and 3.3 for petroleum coke and carbon active, respectively. Heat treatment of these blends at 1470 °C for 5 h resulted in the synthesis of boron carbide powders, which contained 0.82 and 0.59 weight percent free carbon, respectively.