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Journal of Nanomaterials
Volume 2013 (2013), Article ID 108076, 11 pages
http://dx.doi.org/10.1155/2013/108076
Research Article

Dense and Cellular Zirconia Produced by Gel Casting with Agar: Preparation and High Temperature Characterization

1Department of Applied Science and Technology, Politecnico di Torino, INSTM Reference Laboratory for Ceramics Engineering, Corso Duca Degli Abruzzi 24, 10129 Torino (To), Italy
2Department of Engineering, University of “Roma Tre,” INSTM Reference Laboratory for Engineering of Surface Treatments, Via della Vasca Navale 79, 00146 Roma (RM), Italy
3Department of Chemical Engineering Materials Environment, University of Rome “La Sapienza,” INSTM Reference Laboratory for Engineering of Surface Treatments, Via Eudossiana 18, 00184 Roma (RM), Italy

Received 25 January 2013; Revised 18 April 2013; Accepted 13 May 2013

Academic Editor: Rachman Chaim

Copyright © 2013 Jean-Marc Tulliani et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A modified gel-casting process was developed to produce both dense and highly porous (40% volume) yttria tetragonal zirconia polycrystal (Y-TZP) using agar, a natural polysaccharide, as gelling agent. A fugitive phase, made of commercial polyethylene spheres, was added to the ceramic suspension before gelling to produce cellular ceramic structures. The characterization of the microstructural features of both dense and cellular ceramics was carried out by FEG SEM analysis of cross-sections produced by focused ion beam. The mechanical properties of the components were characterized at room temperature by nanoindentation tests in continuous stiffness measurement mode, by investigating the direct effect of the presence of residual microporosity. The presence of a diffuse residual microporosity from incomplete gel deaeration resulted in a decay of the bending strength and of the elastic modulus. The mechanical behavior of both dense and cellular zirconia (in terms of elastic modulus, flexural strength, and deformation at rupture) was investigated by performing four-point bending tests at the temperature of 1500°C.