Microwave-Material Interaction in Oxide Ceramics with Different Additives

Abstract:

A systematic study upon microwave (2.45 GHz frequency) and conventional heating (resistance heating furnace) was undertaken on porosity, grain growth and densification of commercial grade Al2O3-ceramics doped with MgO (aliovalent doping), with ZrO2 (grain boundary pinning) and with additives promoting elongated grain growth (LaAlO 3 and La2O3, AlPO4). Processes accompanied by a strong non-equilibrium situation, e.g., dissolution, segregation, vacancy formation, are influenced by the presence of the microwave field during heat treatment, visible on microstructure differences of microwave as compared to conventionally sintered samples. Regular grain growth is almost not affected by the microwave field, but the on-set of exaggerated grain growth and pore coalescence is delayed and occurs at higher density as compared to conventional sintering. Such microstructure differences seem to be more pronounced if the surface to volume ratio of the samples is low, therefore volumetric heating has a larger contribution to transport phenomena as compared to small samples.

• Periodical: Advances in Science and Technology (Volume 45)
• Pages: 845-850
• DOI: https://doi.org/10.4028/www.scientific.net/AST.45.845
• Online since: October 2006
• Authors: Monika Willert-Porada, Zahra Negahdari, T. Gerdes, Achim Müller, M. Paneerselvam
• Keywords: Additive, Aluminum (Al), Microstructure, Microwave Sintering

References

[1] M. Sato et al., Development of Microwave kilns for industries in Japan, 9th International Conference on Microwave and High Frequency Heating, Loughborough, UK, (2003).

[2] T. Gerdes, M. Willert-Porada, Technology Development for Microwave Sintering, 9thCimtec World Ceramic Congress, Ceramics: Getting into 2000's - Part C, Ed. P. Vinzenzini, Techna Srl, 379-388 (1999).

[3] M. Willert-Porada, Novel Aspects of Microwave Processing of Ceramic Materials, in Ceramic Processing Science and Technology, ed. H. Hausner, G. Messing, Shin- ichi Hirano, Amer. Ceram. Soc., Westerville, OH, Ceram. Trans. Vol. 51 , S. 501-506 (1995).

[4] S. Vodegel, C. Hannappel, M. Willert-Porada, Gefügeeinstellung beim Mikrowellensintern von Al2O3, Metall 48.

[3] S. 206-210 (1994).

[5] S. Vodegel, Mikrowellensintern von Aluminiumoxid, Fortschr. Ber. VDI Reihe 3, Nr. 354 (1994), ISBN 3-18-335403-9.

[6] M. Willert-Porada, W. Bartusch, G. Dhupia, G. Müller, A. Nagel, G. Wötting, Material and Technology Development for Microwave Sintering of High Performance Ceramics, in Ceramics-Processing, Reliability, Tribology and Wear, Euromat Vol. 12, Ed. G. Müller, Wiley-VCH, pp.87-93 (2000).

DOI: 10.1002/3527607293.ch15

[7] M. Willert-Porada, A Microstructural Approach to the Origin of Microwave Effects in Sintering of Ceramics and Composites, Ceram. Trans. Vol. 80 (Microwaves IV), Ed. D. Clark, D. Lewis, W. Sutton, B. Krieger, 153-163 (1997).

[8] K.I. Rybakov, V.E. Semenov, Phys. Rev. B, 49, 64-68 (1994), S.A. Freeman, J.H. Booske, and R.F. Cooper Phys. Rev. Lett. 74, 2042-2045 (1995).

[9] M. Willert-Porada, S. Vodegel, Verfahren zur Sinterung von hochschmelzenden anorganischen Stoffen mit geringen dielektrischen Verlusten mittels Mikrowellenstrahlung, P 42 24 974. 0, (1992), DE 42 24 974 A1.

[10] Chang-Hoon Kim, Seo-Yong Cho, In-Tae Kim, Woon-Jo Cho, Kug-Sun Hong, Twin structures in lanthanum, praseodymium, and neodymium aluminate ceramics, MRS 36 (2001) 1561-1571.

DOI: 10.1016/s0025-5408(01)00495-0

[11] Jae-Gwan Park, and A. N. Cormack, Defect Structures and Nonstoichiometry in Lanthanum Hexa-aluminate Journal of the European Ceramic Society 19 (1999) 2249-2256.

DOI: 10.1016/s0955-2219(99)00123-5