The effect of sintering parameters on spark plasma sintering of B4C

The effects of sintering temperature, heating rate, and holding time on the density and hardness of the spark plasma sintered B4C were investigated. Experimental results are compared with the predictions from computational thermodynamics. It is explained how the choice of sintering parameters can affect the mechanical properties of the sintered samples. The fundamental mechanisms of how the sintering parameters affect the properties of the sintered B4C are discussed with the sintering experiments and the predictions from the CALPHAD (Calculation of Phase Diagrams) approach. The effect of the number of graphite foil layers to pack the powder was also investigated. It is proposed that increasing the number of graphite foil layers may increase the driving force for the C-B2O3 reaction to proceed. Higher density and hardness is thus achieved with the removal of free carbon and B2O3 from the sample.