Pressureless sintering of ZrB ₂ ceramics codoped with TiC and graphite

In this research, the pressureless sintering of ZrB ₂ composites were studied to obtain the highest densification and investigate the effects of TiC (2–10% wt) and graphite (1–2% wt) additives on the sinterability. The results showed that by adding TiC, the porosity and water absorption of the samples decreased, resulting in an increase in the density of the samples up to ~98% of the theoretical density. The addition of graphite and TiC reduced the surface oxide layers, improved the density and prevented the grain growth. The graphite additive reacted with B ₂ O ₃ and ZrO ₂ and allowed the system to achieve a complete densification at 2000 °C. Both TiC and graphite additives were completely consumed during the sintering process and the in-situ formation of TiB ₂ and ZrC phases were proved.