Temperature-induced gelation of concentrated sialon suspensions
authors Xu, X; Ferreira, JMF
nationality International
journal JOURNAL OF THE AMERICAN CERAMIC SOCIETY
keywords ENZYME-CATALYZED REACTIONS; RHEOLOGICAL PROPERTIES; ALUMINA SUSPENSIONS; CERAMICS
abstract A temperature-induced gelation method has been developed for the preparation of sialon green bodies composed Of Si3N4, AlN, Y2O3, and Al2O3. Using a polyester/polyamine condensation polymer as dispersant, stable suspension containing sialon, precursor powders could be prepared in methyl ethyl keton (MEK)/ethanol (E) solvent mixture with solids loading as high as 60 vol%. The solvency of the dispersant in MEK/E decreased dramatically on cooling. The sedimentation tests showed that the settling behavior changed from slow accumulation at similar to 20 degrees C to fast deposition of clusters at -15 degrees C, because of the collapse of dispersant chains adsorbed at the surface of the particles. Steady shear viscosity and oscillatory measurements performed for 60 vol% suspensions as functions of temperature and added amounts of dispersant proved that suspensions were of low viscosity and high stability at room temperature, becoming predominantly very highly viscous and elastic as temperature decreased. The gelation mechanism was mainly based on the coiling up of dissolved dispersant molecules, inducing in situ gelation and the formation of a rigid network bridging the suspended particles. The green bodies showed negligible shrinkage during gelation, a small shrinkage during drying, homogeneous microstructures, narrow pore size distributions, and high relative density. It was possible to achieve dense alpha-sialon ceramics through pressureless sintering at 1750 degrees C for 2 h.
publisher BLACKWELL PUBLISHING INC
issn 0002-7820
year published 2005
volume 88
issue 3
beginning page 593
ending page 598
digital object identifier (doi) 10.1111/j.1551-2916.2005.00160.x
web of science category Materials Science, Ceramics
subject category Materials Science
unique article identifier WOS:000227857100015
  ciceco authors
  impact metrics
journal analysis (jcr 2019):
journal impact factor 3.502
5 year journal impact factor 3.475
category normalized journal impact factor percentile 91.071
dimensions (citation analysis):
altmetrics (social interaction):



 


Sponsors

1suponsers_list_ciceco.jpg