Available online at www.sciencedirect.com Journal of the European Ceramic Society 30 (2010) 1211–1221 Review Densification and microstructure evolution of Y-Tetragonal Zirconia Polycrystal powder during direct and hybrid microwave sintering in a single-mode cavity Sylvain Charmond, Claude Paul Carry, Didier Bouvard ∗ SIMaP, Grenoble Institute of Technology, Université Joseph Fourier, CNRS, BP 75, F-38 402 St-Martin d’Hères, France Received 1 July 2009; received in revised form 4 November 2009; accepted 26 November 2009 Available online 19 January 2010 Abstract The densification and microstructure changes of 2mol% yttria-stabilized zirconia nanopowder have been investigated during direct and hybrid microwave sintering. Microwave heating tests were achieved in a resonant single-mode cavity at 2.45GHz and a cylindrical SiC susceptor was used for hybrid sintering experiments. Constant heating rate runs (25 ◦ C/min) were controlled by adjusting the position of a sliding piston at constant forward microwave power. The temperature on the upper surface of the specimen was measured with an infrared camera. The final densities and the microstructures observed by SEM were compared to those of conventionally sintered materials. Homogeneous microstructures have been obtained by hybrid heating whereas direct microwave heating led to rather heterogeneous microstructures due to thermal gradients. Nevertheless, microwave-sintered materials always exhibited higher final densities for a given sintering temperature. This significant enhancement of the densification process was particularly observed in the intermediate sintering stage (1200–1350 ◦ C range). Besides, grain growth was found to be mainly influenced by the sintering temperature rather than by the heating mode. © 2009 Elsevier Ltd. All rights reserved. Keywords: Microwave processing; Sintering; Grain size; Microstructure; ZrO 2 Contents 1. Introduction ........................................................................................................... 1212 2. Experiments ........................................................................................................... 1213 2.1. Microwave system setup .......................................................................................... 1213 2.2. Experimental procedure .......................................................................................... 1214 2.3. Direct microwave sintering ....................................................................................... 1215 2.4. Hybrid microwave sintering ....................................................................................... 1216 3. Results: characterization of sintered materials ............................................................................. 1217 3.1. Final density .................................................................................................... 1217 3.2. Microstructure ................................................................................................... 1217 3.3. Sintering temperature–final density–grain size ...................................................................... 1218 4. Discussion ............................................................................................................ 1220 5. Conclusion ............................................................................................................ 1221 References ............................................................................................................ 1221 ∗ Corresponding author. Tel.: +33 476 82 63 07; fax: +33 476 82 63 82. E-mail address: didier.bouvard@grenoble-inp.fr (D. Bouvard). 0955-2219/$ – see front matter © 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2009.11.014