Ultra-low shrinkage and high-strength porous TiB/TiB2 ceramics via low temperature in-situ reaction sintering combined with the freeze-drying method |
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Affiliation: | School of Materials Science and Engineering, Harbin Institute of Technology, Harbin, 150080, PR China |
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Abstract: | Ultra-low shrinkage porous TiB2-based ceramics reinforced by the TiB whiskers are firstly fabricated through the in-situ reaction between TiB2 and Ti at a low temperature (1450 °C). The growth of TiB whiskers with a high aspect ratio at pore channels is achieved through a vapor-solid growth mechanism, while low aspect ratio TiB whiskers at pore walls are dominated by a solid-state reaction diffusion growth, forming bimodal distribution whiskers in porous TiB2-based ceramics. The overlapping TiB whiskers with low-speed growth at particle contact points can significantly inhibit the shrinkage and improve the strength of porous TiB2-based ceramics. When the solid content is fixed at 20 vol% and 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. |
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Keywords: | TiB whiskers Low temperature Compressive strength |
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