ISSN 0862-5468 (Print), ISSN 1804-5847 (online) 

Ceramics-Silikáty 43, (1) 12 - 17 (1999)

Bača Ľuboš, Pach Ladislav, Hrabě Zdenek
Department of Ceramics, Glass and Cement, Faculty of Chemical Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovak Republic

Boehmite derived alumina gels (grains and sticks) containing Fe₂O₃ in the range of 1 to 6 wt. % were sintered at 1350 °C for 3 hours. Relative density, strength and unexpectedly also the size of α-Al₂O₃ crystals increase with Fe₂O₃ content. A bimodal microstructure of anisotropic α-Al₂O₃ crystals is observed at and above 3 wt.% content of Fe₂O₃. Anisotropic growth of α-Al₂O₃ crystals is attributed to the presence of Fe²⁺ and to the specific nucleation effect of α-Fe₂O₃. Due to high strength and the relatively small size of α-Al₂O₃ crystals a Fe₂O₃ content of 3 wt.% seems most appropriate when applications of the material as abrasive grains are intended.

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