Influences of B4C content and particle size on the mechanical properties of hot pressed TiB2-B4C composites

TiB2 ceramic has attracted many attentions due to its excellent performances both on mechanical and functional properties. However, it is still very difficult to obtain TiB2 bulks with full densification. Herein, TiB2-B4C composites were prepared via hot pressing at 1900 degrees C under the pressure of 35 MPa with TiB2 and B4C as the raw materials. The influences of B4C content (0, 10 vol%, 20 vol% and 30 vol%) and particle size (0.50 mu m, 3.12 mu m and 7.09 mu m) on the phase composition, relative density, microstructure and mechanical properties of TiB2-B4C composites were investigated. The using of 0.50 mu m B4C brought more B2O3 which induced oriented growth of TiB2 grains and coarsened the obtained composites. When the raw B4C powders were 3.12 mu m and 7.09 mu m, the obtained composites with 20-30 vol% B4C could be fully densified. TiB2-30 vol% B4C composite prepared from 3.12 mu m B4C powder resulted in the optimal mechanical properties. The bending strength, Vickers hardness, fracture toughness were 671 MPa, 27.93 GPa, and 3.91 MPa center dot m(1/2), respectively. The excellent performance was attributed to its fine and homogenous microstructure.