Effect of K 2CO 3, and FeCl 3 on the formation of B 4C through carbothermal reduction of B 2O 3

Abstract

The formation of B 4C through carbothermal reduction of B 2O 3 has been studied by varying boron to carbon molar ratio (B:C = 4: x) where x = 2.66/2.0/0.833. The effect of potassium carbonate (K 2CO 3), and ferric chloride (FeCl 3) on the elimination of residual free carbon has been examined. The reaction was studied in a range of temperature of 1300–1625 °C for 0.5 h in 1 atm. argon. Residual free carbon was found with carbon content as low as 2.66 in the reaction mixture (B:C = 4:2.66). Addition of K 2CO 3 to reactant mixture has been found to decrease the free residual carbon. B 2O 3 has been found lost totally when the carbon content in the reactant mixture is very small (B:C = 4:0.833). Addition of FeCl 3 was found to decrease the loss of boric species by forming FeB, and to stabilize graphitic carbon. No peak, corresponding to free carbon was seen in B 4C formed from reactant mixture containing boron and carbon in the ratio of (B:C = 4:2). Large number of needles/platelets were formed with the addition of FeCl 3/K 2CO 3.