High strength-high toughness B4C-TiB2 composites

This paper presents results on the fracture toughness and strength of a boron carbide (B4C) ceramic produced by uniaxial hot pressing using TiO2 and C as additives. The composition of the mix was adjusted so that no free carbon or TiO2 was left in the sintered compacts. All samples were hot-pressed for one hour at 2000 C and at a pressure of 20 MPa in a static argon gas atmosphere. The resulting high values for strength are attributed to the high values for fracture toughness caused by the presence of uniformly distributed TiB2 particles and a well-sintered fine-grained B4C matrix. The results show that the reaction hot pressing of B4C ceramics with the addition of TiO2 and C enables the production of high-strength high-toughness B4C ceramics at temperatures significantly lower than the traditional sintering temperature involving C as an additive. With a flexural strength of 621 MPa and a fracture toughness of over 6.1 MPa x sq rt m, along with light weight and high hardness, boron carbide and its composites now have the potential of becoming important structural ceramics. (AIAA)