A novel colloidal processing route to alumina ceramics
authors Ganesh, I; Sundararajan, G; Olhero, SM; Torres, PMC; Ferreira, JMF
nationality International
journal CERAMICS INTERNATIONAL
author keywords Alumina; Gelcasting; Hydrolysis assisted solidification; Hydrolysis induced aqueous gelcasting; Rheology; Near-net shape; Radome
keywords HYDROLYSIS-ASSISTED SOLIDIFICATION; AQUEOUS GELCASTING PROCESS
abstract The fabrication of complex-shaped alumina ceramics following a new near-net shape technique based on hydrolysis induced aqueous gelcasting (GCHAS) is reported in this paper. Aqueous suspension containing 50 vol.% solids loading was prepared by dispersing alumina in an aqueous solution of methacrylamide and methlynebisacrylamide (17 wt.% in 6:1) using polycarboxylic acid as dispersing agent. Consolidation was accomplished by adding a polymerization initiator, a catalyst and AlN powder (4 wt.%). For comparison purposes, alumina ceramics were also consolidated by aqueous gelcasting (GC) and by hydrolysis assisted solidification (HAS) from the same concentrated suspensions, and by conventional dry pressing (DP) from freeze dried granules prepared from the same suspensions by freeze granulation. Among the four shaping techniques used, GCHAS was found to be best for consolidating near-net shape alumina components like thin wall radomes with the highest green strength ever reported for alumina ceramics. Green samples were sintered for 2 h at 1600 degrees C and then characterized for microstructure and mechanical properties. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.
publisher ELSEVIER SCI LTD
issn 0272-8842
year published 2010
volume 36
issue 4
beginning page 1357
ending page 1364
digital object identifier (doi) 10.1016/j.ceramint.2010.01.022
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000277745100025
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journal impact factor 3.057
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