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

Large scale B4C nano-powders were synthesized via a novel ball milling assisted reaction coupling self-propagating high temperature synthesis method using Mg, B2O3 and CH2H3Cl as the starting materials. The XRD, FTIR, Raman, EDX, FSEM, TEM, HRTEM and SAED were used to characterize the B4C 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 B4C (C-B4C) and homemade B4C (H-B4C) ceramics were prepared by spark-plasma sintering method at 1700 °C under 30 Mpa. Compared with the C-B4C ceramic, the values of relative density, vickers hardness and fracture toughness of the H-B4C ceramic were increased by 2.1%, 9.2% and 20.1%, respectively, demonstrating high sintering activity of the homemade B4C nano-powders.