Microstructure and mechanical properties of B4C-TiB2 composite ceramic fabricated by reactive spark plasma sintering

摘要

B4C-TiB2 composite ceramic was prepared by reactive spark plasma sintering, using amorphous B, Ti, and graphite as the raw materials. The reaction process and the phase composition in the process of sintering were studied. The effects of the ratio of raw materials and sintering process on the microstructure and mechanical properties of B4C-TiB2 composite ceramic were investigated. The composition of the sintered sample was B4C, TiB2, and bits of residual unreacted graphite. B and Ti preferentially reacted to form TiB2 at 800 degrees C, and then B and graphite reacted to form B4C at 1250 degrees C. The 75 vol% B4C-25 vol% TiB2 composite ceramic synthesized with 60.6 wt% B, 25.8 wt% Ti, and 13.6 wt% graphite and sintered at 1900 degrees C for 15 min resulted in nearly full densification and optimal mechanical properties. The relative density, Vickers hardness, fracture toughness, and flexural strength were 98.6 +/- 0.01%, 26.6 +/- 0.01 GPa, 5.9 +/- 0.13 MPa.m(1/2), and 605 MPa, respectively.