Ultra-Low Shrinkage and High-Strength Porous Tib/Tib2 Ceramics Via Low Temperature In-Situ Reaction Sintering Combing Freeze-Drying Method

Low shrinkage porous TiB 2 -based ceramics reinforced by the overlapping TiB whiskers network are firstly fabricated through the in-situ reaction between TiB 2 and Ti at low temperature (1450 °C). The whiskers with a high aspect ratio at pore channel are controlled by a vapor-solid growth mechanism, while low aspect ratio whiskers at pore wall are dominated by solid-state reaction diffusion growth, forming a bimodal distribution TiB whiskers. The overlapping TiB whiskers with low-speed growth at particle contact points can significantly inhibit the shrinkage and improve the strength of porous TiB 2 -based ceramics. When the target TiB content changes from 0 to 80 vol.%, the porous ceramics show slight sintering shrinkage (from 1.1 to 4.7%) and high porosity (from 79.3 to 73.7%) while keeping high compressive strength of 1.8 - 18.2 MPa, which is higher than most reported porous ceramics at the same porosity