B_4C-TiB_2 Composites via Reactive Hot Pressing

摘要

B_4C/IiB_2 ceramic composites having 5-10-15 vol % TiB_2 have been prepared via reactive hot pressing of B_4C, TiO_2 and C powder mixture. Reactive hot pressing were carried out at 2273 K and 2373 K applying 50 MPa pressure under argon atmosphere for 1 hour. The effect of TiB_2 amount of composite and sintering temperature on sintering behavior and some mechanical properties of reactive hot pressed composites were investigated. The highest theoretical density that could be achieved, being 99.6 %, was with the composite having 5 % TiB_2 following reactive hot pressing at 2000℃ applying 50 MPa pressure under argon atmosphere for 1 hour. The highest strength level achieved with the same composite (B_4C-5 vol.% TiB_2) was 450 MPa. The fracture toughness of the composite was found to be 4.2 MPa. m~(1/2). Increasing TiB_2 content in composites led to increasing porosity in B_4C-TiB_2 samples and decreasing mechanical properties.