2017 年 64 巻 10 号 p. 538-546
Dense B4C/TiB2 composite ceramics have been fabricated from the amorphous B and C, and fine TiC powders (25 nm in size Ps), using pulsed electric current pressure sintering (PECPS) at 2173 K under 50 MPa for 6.0 × 102 s in a vacuum. During PECPS the solid-state reaction between B and C was induced around 1373 K and almost at the same time TiB2 phase was gradually formed, followed by a continuous formation of B4C matrix including TiB2 particles. On the other hand as the reference, two kinds of B4C/TiB2 composites from the B/C mixtures and TiB2 powders (1.86 μm and 58 nm in Ps) were also fabricated as the same manner. The former composites using TiC showed high relative density ≥ 98.9% up to 11 vol% TiB2 and improved mechanical properties, such as three-point bending strength σb of 650 MPa, Vickers hardness Hv of 33.5 GPa and fracture toughness KIC around 5.45 MPa·m1/2 at the composition of B4C/TiB2 = 93/7 vol%, however, the latter composites revealed lower relative densities of 96.5% at 7 vol%TiB2 composition and deteriorated mechanical behaviors as Ps of TiB2 increased.
