ADVANCES IN MODELING OF MICROWAVE SINTERING 12 th Seminar Computer Modeling in Microwave Engineering & Applications, Grenoble, France, March 8-9, 2010 21 Multiphysics Simulation of Microwave Sintering in a Monomode Cavity Didier Bouvard, Sylvain Charmond and Claude P. Carry Laboratoire SIMAP, Grenoble INP, Saint Martin d’Hères, France The simulation of sintering of a ceramic powder in a monomode microwave cavity has been carried out with COMSOL finite element software. At a given time, a stationary calculation provides the electromagnetic field in both the cavity and the compact when we assume an incident power, and when we suppose that dielectric permittivity and thermal parameters depend on relative density and temperature. From the electric field in the compact, the value of the generated heat is deduced, and a transient thermal calculation is then run with this value as a heat source and with radiating losses at the boundaries of the compact. The density of the compact is updated through a prescribed densification law, and finally, temperature and density kinetics are obtained. The developed tool is used to analyze the influence of the insulation device on heating. The effect of introducing a susceptor in the cavity for the purpose of hybrid heating is also investigated. Introduction Microwave heating of dielectric materials results from the absorption by molecule polarization of part of the energy transported by an oscillating electric field. As compared to conventional heating, it results in shorter heating times and thus may slow down unwanted microstructural changes arising during sintering, such as grain growth in fine grain ceramics. However, microwave sintering is a complex process, and is much more difficult to control than conventional sintering. Even such a basic issue as measuring the temperature of the material undergoing sintering is a problem. Also, insulation and positioning of a compact may be critical. Computer models representing the process as a whole would be of great help in the effort of understanding the microwave sintering process and bringing it to an industrial scale. Microwave sintering involves several phenomena that are strongly coupled to each other: electromagnetism, heat transfer and sintering. For example, electromagnetic energy absorption that controls heating (and thus also controls sintering) depends on temperature-dependent material parameters and on the electromagnetic field, which changes as the sintering progresses. Taking into account such coupling effects is necessary for realistic modeling of microwave sintering. Macroscopic scale simulations of microwave sintering, coupling electromagnetism and heat transfer, have been presented in the literature [1-3]. These models are mainly based on either the finite element method or finite difference time domain techniques, and most of these studies do not introduce densification. Notable exceptions are the model by Birnboim and Carmel [4], who calculated density gradients in complex shape components, and the model by Riedel and Svoboda [5], who found density and grain size distributions in a cylindrical compact surrounded by a susceptor inside an axisymmetric resonant cavity. We present in this paper several results of a 3D finite element simulation of microwave sintering in the monomode cavity furnace designed at Grenoble INP. This simulation takes into account electromagnetism, heat transfer and densification, as well as, in part, coupling of these