Gelcasting of alumina nanopowders based on gelation of sodium alginate |
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Authors: | H Akhondi E Taheri-Nassaj H Sarpoolaky A Taavoni-Gilan |
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Affiliation: | 1. Department of Materials Science and Engineering, Tarbiat Modares University, P.O. Box 14115-143, Tehran, Iran;2. Department of Materials Science and Engineering, Iran University of Science and Technology, P.O. Box 16844, Tehran, Iran |
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Abstract: | The alumina nanopowder was synthesized via the sol–gel method. θ-Alumina with crystallite size in the range of 25–110 nm was crystallized by calcination of the powder at 900 °C for 1 h. Sodium alginate, a natural innoxious polymer, was applied for in situ forming process of an Al2O3 green body, using calcium phosphate as a solidifier agent. Sodium hexa metaphosphate was also utilized as a chelator. Rheological and gelation behaviors of resultant slurry were analyzed. The viscosity of slurries with 15 vol.% alumina and 1.8 vol.% calcium phosphate dispersed by 1 wt.% sodium alginate solution, was less than 800 mPa s. The green bodies from the gelcasting process were dried at room temperature for 36 h and pressureless sintered at 1500 °C for 3 h. A uniform microstructure without huge grain growth was revealed by SEM. |
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Keywords: | D Alumina Nanopowder Gelcasting Sodium alginate |
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