Effect of SiC on Interfacial Reaction and Sintering Mechanism of TiB ₂

Abstract

Compacts of TiB 2 with densities approaching 100% are difficult to obtain using pressureless sintering. The addition of SiC was very effective in improving the sinterability of TiB 2 . The oxygen content of the raw TiB 2 powder used in this research was 1.5 wt%. X‐ray photoelectron spectroscopy showed that the powder surface consisted mainly of TiO 2 and B 2 O 3 . Using vacuum sintering at 1700°C under 13–0.013 Pa, TiB 2 samples containing 2.5 wt% SiC achieved 96% of their theoretical density, and a density of 99% was achieved by HIPing. TEM observations revealed that SiC reacts to form an amorphous phase. TEM‐EELS analysis indicated that the amorphous phase includes Si, O, and Ti, and X‐ray diffraction showed the reaction to be TiO 2 + SiC → SiO 2 + TiC. Therefore, the improved sinterability of TiB 2 resulted from the SiO 2 liquid phase that was formed during sintering when the raw TiB 2 powder had 1.5 wt% oxygen.