Effects of heat-treatment temperature and starting composition on morphology of boron carbide particles synthesized by carbothermal reduction

Carbothermal reduction using B2O3 and carbon black was applied for synthesis of B4C powder and the effects of heat-treatment temperature and starting composition of raw mixture on morphology of B4C particles were investigated. Morphology of B4C particles synthesized at 1450 °C was mainly spherical shapes. The B4C powder synthesized at 1550 °C was large and changed in morphology from polyhedral to skeletal shape, and particle size of B4C increased with an increase in the amount of B2O3 in the starting mixtures. The B4C powder synthesized beyond 1650 °C consisted from dendrite-like particles aggregated by small primary particles. Morphology of the primary B4C particles synthesized at 1750 °C changed from polyhedral to rounded shape with increasing the amount of B2O3 in the starting mixtures. It is clarified that heat-treatment temperature and the starting compositions of raw mixtures mainly affected B4C nuclei number along with primary particle size and morphology of primary B4C particles, respectively.