Microstructural and Mechanical Properties of Boron Carbide Ceramics by Methanol Washed Powder

Abstract

Boron carbide (B₄C) is currently used in lightweight armors and high temperature materials, because it has high meting point, good hardness, low specific gravity and good mechanical properties. The sintering of boron carbide, however, is restricted by its high covalent bonding and B₂O₃ coatings on B₄C particles surface which can cause a microstructural coarsening during sintering. Therefore, it is necessary to remove B₂O₃ film of By4C particles surface to restrict microstructural coarsening and densification of B₄C. B₄C ceramics were fabricated by a hot-press sintering and its sintering behavior, microstructure and mechanical properties were evaluated. The relative density of B₄C ceramics were obtained by a hot-press sintering reached as high as 99% without any sintering additives. The mechanical properties of B₄C ceramics was improved by a methanol washing which can remove B₂O₃ phase from a B4C powder surface. This improvement is resulted from the formation of homogeneous microstructure because the grain coarsening was suppressed by the elimination of B₂O₃ phase. Particularly, the mechanical properties of the sintered samples using a methanol washed powder improved compared with the samples using an as-received commercial powder.