Microwave Processing Laboratory - Other 95-1

Modeling of Multi-Frequency Microwave Sintering of ZnO Ceramic

A. Birman¹, B. Levush¹, Y. Carmel¹, D. Gershon¹, D. Dadon², L. P. Martin³ and M. Rosen³
¹Institute for Plasma Research, University of Maryland, College Park, MD 20742
²N.R.C.N., P.O. Box 9001, Beer Sheva, Israel
³Johns Hopkins University, Baltimore, MD 21218

Ceramic Transactions 54, 305-312 (1995)

Abstract. To gain better insight of microwave heating of ceramic materials and to optimize this process, we have developed a code modeling the heat propagation in the ceramic. The model takes into account the variation of the heat conduction coefficient, specific heat and permittivity with temperature. In addition, the heat conduction coefficient and permittivity dependence on the porosity is modeled using Maxwell Garnet mixing theory (MGT). The code was used to model experiments of ZnO microwave heating. These computations prove that the model used in the code is capable of reproducing the salient features of the heating process. The code was modified to allow modeling of simultaneous microwave heating at different frequencies. In particular, heating of ZnO sample with two microwave sources at widely separated frequencies (2.45 GHz and 28 GHz) showed that it is possible to keep a homogeneous temperature profile across the sample throughout the sintering process.