Multiphysics modeling of metal ceramic compact for microwave processing

A multiphysics model of metal powder embedded ceramic matrix is developed in order to explore their usage for the microwave processing and sintering application. The development of the required model is facilitated by introducing the concept of the effective permittivity and permeability of the mixture of the metal powder and the base matrix. The effective dielectric and magnetic properties of the mixture are estimated by Lichtenecker´s mixture formula using the complex permittivity and permeability of the iron metal powder and nano alumina powder. The simulation is carried out using COMSOL multiphysics software, where a spherical sample of the mixture is placed inside a cavity and the microwave energy is incident from the rectangular waveguide into the cavity. In the first step, the electromagnetic field distribution inside the sample is studied by varying its position inside the cavity. The electromagnetic model data is then fed to the thermal model of the COMSOL, and the simulation is carried out for 600 seconds with the microwave power of 500 watt. It is observed that the optimum heating pattern is obtained for a mixture of 5% iron metal powder and 95% Alumina. It is also noticed that the maximum temperature rise is obtained when the sample is placed at the position of maximum electric field, which is due to the fact that the iron powder has quite high value of dielectric loss factor as compared to the magnetic loss.