Abstract
The formation of whiskers and platelets of B4C and BN has been studied through carbothermal reduction of B2O3. In the absence of any additive, neither whiskers nor platelets have formed from B2O3 and carbon black. K2CO3 which forms a low melting liquid and NiCl2 which act as catalyst in gasification of carbon were used to facilitate the growth of whiskers and platelets. NiCl2, K2CO3, carbon black and B2O3 were reacted in a weight ratio (NiCl2:K2CO3:C:B2O3= 5:5:12:17.4) and studied the formation of B4C and BN in the temperature range of 940°C to 1500°C in 1-atm. argon and 1-atm. nitrogen respectively. Whiskers and platelets of different sizes have formed at 1100–1500°C. The whiskers have been observed to form by vapor-liquid-solid growth mechanism. The effect of NiCl2 and K2CO3 on the morphology of B4C and carbon has been studied. NiCl2 and K2CO3 have been found to accelerate the growth of whiskers and platelets.
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