Titanium diboride (TiB2) was hot‐pressed at a temperature of 1800°C, and silicon nitride (Si3N4) was added as a sintering aid. The amount of Si3N4 that was added had a significant influence on the sinterability and mechanical properties of the TiB2. When a small amount (2.5 wt%) of Si3N4 was added, the Si3N4 reacted with titania (TiO2) that was present on the surface of the TiB2 powder to form titanium nitride (TiN), boron nitride (BN), and amorphous silica (SiO2). The elimination of TiO2 suppressed the grain growth effectively, which led to an improvement in the densification of TiB2. The formation of SiO2 also was deemed beneficial for densification. The mechanical properties‐especially, the flexural strength‐were enhanced remarkably through these improvements in the sinterability and microstructure. On the other hand, when a large amount (greaterthan equal to5 wt%) of Si3N4 was added, the mechanical properties were not improved much, presumably because of the extensive formation of a glassy Si‐Ti‐O‐N phase at the grain boundaries.

The effect of hot-pressing temperature on the densification behavior and mechanical properties of titanium diboride (TiB 2 ) was investigated. TiB 2 specimens were hot-pressed for 1 h at temperatures in the range of 1500°-1800°C, with an addition of 2.5 wt% of silicon nitride (Si 3 N 4 ) as a sintering aid. The density increased markedly at temperatures in the range of 1500°-1600°C and remained constant thereafter. The formation of a eutectic liquid at 1550°C was attributed to the steep increase in density. The hot-pressing temperature also improved the mechanical properties, such as the flexural strength, Vickers hardness, and fracture toughness of the specimens. Similar to the density, the mechanical properties improved remarkably at ϳ1550°C, so that optimum properties were obtainable at temperatures as low as 1600°C.