Abstract
The TiB2-TiNxCy composite ceramics, which have high hardnesses and electrical conductivities, and can be used for electric discharge machining, were fabricated by the reaction sintering of B4C and TiN powders. The TiN powders containing 0-20mass% B4C-additives were pressed under a pressure of 100MPa, and then sintered at 2100°C for 3.6ks in an ambient Ar gas of normal pressure. As a result, the 27.5mass% TiB2-TiNxCy composite, for example, was obtained by the reaction sintering of TiN powders containing 8mass% B4C-additive. The composite had a maximum relative density of 96.1% and showed improved hardness by -1.5 times, fracture toughness of KIC by -1.7 times, Young's modulus by -1.3 times, electrical conductivity by -1.7 times compared with those of pure TiN ceramics with a relative density of 87.7%. The hardness and electrical conductivity of the 67.0mass% TiB2-TiNxCy composite obtained from the TiN powders containing 20mass% B4C-additive were 2.0 and 2.2 times higher than those of pure TiN ceramics, respectively, in spite of the lower relative density of 90.9%.
