The sintering behavior, microstructure and mechanical properties of boron carbide ceramics, which were fabricated by a spark plasma sintering process, were investigated. The relative density of B4C ceramics using a spark plasma sintering method reached as high as 99% theoretical at a lower temperature than a conventional sintering method, and in addition, without any sintering additives. The mechanical properties of B4C ceramics could be improved by soaking at 1,300 oC during the sintering process which removed the B2O3 phase from the B4C powder surface. A remarkable improvement of mechanical properties could be achieved by the introduction of a soaking process during the spark plasma sintering process. In particular, the fracture toughness values of the specimens which experienced the B2O3 removal process improved by over 30% compared with the specimens without this process. These achievements resulted from the formation of a fine and homogeneous microstructure because the grain coarsening was suppressed by the elimination of the B2O3 phase.

Keywords: B4C, Microstructure, Mechanical properties, Spark plasma sintering.