Processing and properties of B4C-based systems combined with TiB2 and SiC

Boron carbide is one of the lightest and hardest ceramics. Properties such as high melting point, high elastic modulus, high corrosion resistance to chemical agents and high neutron absorption cross section have generated a great interest in B4C - based ceramics. As a result, this carbide is currently used in many advanced application fields, including cutting tools, high temperature thermoelectricity conversion, armor materials and nuclear industry. In spite of that, B4C is not exploited to its full potential mainly due to its brittleness and extremely poor sinterability. As many other covalent type carbide ceramics, temperature in excess of 2000 °C and/or pressure assisted techniques are required to obtain the full densification. In this talk, we first explore different approaches to the processing and sintering of B4C with the aim to enhance the densification. Then we focus on the B4C - TiB2 system that is par¬ticularly attractive because the addition of TiB2 allows not only an improvement of fracture toughness and strength, but also a better machinability, thanks to the possibility of using the EDM technique. We analyze the effects of: -different TiB2 content on the composite proper¬ties, -further secondary phases used to improve either sinterability (such as WC), or high temperature properties/oxidation behavior (such as SiC). Finally, we compare the properties of these materials with reference B4C-based materials, discussing advantages/drawbacks of different processes.