Reaction coupling preparation of high sintering activity boron carbide nano-powders

Abstract Large scale B 4 C nano-powders were synthesized via a novel ball milling assisted reaction coupling self-propagating high temperature synthesis method using Mg, B 2 O 3 and CH 2 H 3 Cl as the starting materials. The XRD, FTIR, Raman, EDX, FSEM, TEM, HRTEM and SAED were used to characterize the B 4 C samples. The optimum endothermic rate was 35%, when the samples presented fine and uniform regular morphology with an average particle diameter of about 100 nm. In addition, the reaction coupling principle, possible chemical reaction mechanism and the effects of the endothermic reaction rate were also discussed. Moreover, the commercial B 4 C (C-B 4 C) and homemade B 4 C (H-B 4 C) ceramics were prepared by spark-plasma sintering method at 1700 °C under 30 Mpa. Compared with the C-B 4 C ceramic, the values of relative density, vickers hardness and fracture toughness of the H-B 4 C ceramic were increased by 2.1%, 9.2% and 20.1%, respectively, demonstrating high sintering activity of the homemade B 4 C nano-powders.