abstract
A new near-net shape forming process called "hydrolysis-induced aqueous gelcasting" (GCHAS) is reported in this paper for the consolidation of ZTA composites, ZTA-30 (70 wt.% Al(2)O(3) + 30 wt.% ZrO(2)) and ZTA-60 (40 wt.% Al(2)O(3) + 60 wt.% ZrO(2)). For comparison purposes, ceramics having the same chemical compositions were also consolidated by hydrolysis-assisted solidification (HAS). All the starting suspensions contained a solids loading of 50 vol.%. In the precursor powder mixtures, 1-5 wt.% of Al(2)O(3) was replaced by equivalent amounts of AIN to enhance or promote or co-promote the consolidation of suspensions by HAS or by GCHAS, respectively. The suspensions for GCHAS were prepared by dispersing the ZTA powder precursor mixtures in a premix solution of 20 wt.% MAM (methacrylamide), MBAM (methylenebisacrylamide) and NVP (n-vinylpyrrolidinone) in 3:1:3 ratio in de-ionized water. Ceramics consolidated via GCHAS exhibited superior mechanical properties after consolidation and after sintering for 1 h at 1600 degrees C in comparison to those consolidated by HAS. (C) 2008 Elsevier Ltd. All rights reserved.
keywords
FRACTURE-TOUGHNESS; ASSISTED SOLIDIFICATION; ALUMINA; ROUTE
subject category
Materials Science
authors
Ganesh, I; Olhero, SM; Torres, PMC; Alves, FJ; Ferreira, JMF
our authors
José Maria da Fonte Ferreira
Retired Professor
Paula Maria da Costa Torres
Assistant Researcher
Susana Maria Henriques Olhero
Assistant Professoracknowledgements
IG thanks SERC-DST (Government of India) for awarded BOYSCAST fellowship (SR/BY/E-04/06). S.M. Olhero wishes to thank to Foundation for Science and Technology of Portugal for the financial support under the grant SFRH/BPD/27013/2006. The financial support of CICECO is also acknowledged.