Comparison of the effects of MoSi2 and CrSi2 on sintering and properties of titanium diboride (TiB2)

Abstract

Titanium diboride (TiB2) is a typical material classified as structural ceramics. However, sintering of TiB2 ceramics is difficult mainly because of a significant fraction of covalent bonds in the structure. In order to obtain dense TiB2 ceramics various additives are used to improve its sinterability. In this study, we investigated effects of MoSi2 and CrSi2 additions on sintering and properties of TiB2 prepared by hot-pressing technique. The sintered materials were characterized in terms of apparent density and microstructure. Their mechanical properties (bending strength, Vickers hardness and fracture toughness) and oxidation resistance were determined. It was found that the obtained composites are characterized by high density and microstructure characteristic for cermets (TiB2-MoSi2). The activators used for sintering did not deteriorate mechanical properties of TiB2 sintered bodies. The oxidation resistance of the polycrystals with chromium silicide addition reaches 1400°C. Based on the carried-out studies, CrSi2 was found to be a promising sintering additive.

Keywords

• borides
• hot pressing
• hardness
• oxidation resistance
• microstructure