B4C ceramics were fabricated by a spark plasma sintering process and their sintering behavior, microstructure and mechanical properties were evaluated. The relative densities of B4C ceramics obtained by spark plasma sintering method reached were as high as a 99% at lower temperature than used in the conventional sintering method, in addition, without any sintering additives. The mechanical properties of B4C ceramics were improved by a methanol washing process which can remove B2O3 coatings from the B4C powder surface. This improvement results from the formation of a fine and homogeneous microstructure because the grain coarsening was suppressed by the elimination of the B2O3 coating. In particular, the fracture toughness of the sintered specimen using a methanol washed powder improved by more than 30% compared with the specimen using an as-received commercial powder.

Keywords: B4C; spark plasma sintering; microstructure; mechanical property