Numerical Simulation of Microwave Sintering of Zinc Oxide


Patrick Fischer

Master's Thesis submitted to the Faculty of the Virginia Tech in partial fulfillment of the requirements for the degree of

Master of Science


Mechanical Engineering


J.R. Thomas

May 8, 1997
Blacksburg, Virginia


Experiments at the University of Maryland Plasma Physics Laboratory have discovered an unusual temperature response in the form of a "thermal wave" which begins at the center and propagates towards the surface of a zinc oxide sample, when heated in a microwave cavity without the presence of oxygen. This effect is believed to be caused by the irregular temperature dependence of the dielectric properties of zinc oxide, particularly dielectric loss. Two thermocouple probes were used to measure the temperature response in a small cylindrical sample of zinc oxide packed in powder insulation, and heated in a microwave oven. In order to determine if the unusual response is caused by the dielectric properties, this work uses a finite-difference mathematical model to simulate the experiments, both for the case of zinc oxide heated in ordinary air, as well as for the case of zinc oxide heated in nitrogen. A revised version of the model is used to determine if the thermocouple probe has any effect on the temperature of the sample. The spatial and temporal temperature distribution results from the model indicate that the thermocouple probe has a negligible effect on the results and that the "thermal wave" can be attributed to the irregular temperature dependence of the dielectric loss of the material.

Full text (PDF) Bytes

The author grants to Virginia Tech or its agents the right to archive and display their thesis or dissertation in whole or in part in the University Libraries in all forms of media, now or hereafter known. The author retains all proprietary rights, such as patent rights. The author also retains the right to use in future works (such as articles or books) all or part of this thesis or dissertation.