Processing materials with microwave energy

Materials Science and Engineering A287 (2000) 153 – 158 www.elsevier.com/locate/msea

Processing materials with microwave energy
David E. Clark *, Diane C. Folz, Jon K. West
Department of Materials Science and Engineering, Uni6ersity of Florida, Gaines6ille, FL 32611 -6400, USA

Abstract Microwave energy (microwave frequency, in this case, includes radio frequencies and ranges from 0.3 MHz to 300 GHz) is being developed as a new tool for high-temperature processing of materials. Examples of the advantages associated with microwave processing include: rapid and uniform heating; decreased sintering temperatures; improved physical and mechanical properties; and, unique properties which are not observed in conventional processes. These advantages observed in materials processed using microwave energy are being attributed to ‘microwave effects’ which are particular to this technology. Researchers at the University of Florida are working to identify and to qualitatively and quantitatively define the mechanisms of microwave–material interactions. A new model has been developed based on the molecular orbital model which predicts the behavior of specific pure materials in a microwave field. Experimental work as well as dielectric property measurements confirm the accuracy of this model in specific cases. Published by Elsevier Science S.A.
Keywords: Microwave processing; Microwave–material interactions; Materials processing

1. Introduction Microwave energy has been developed primarily for communications and some areas of processing such as cooking food, tempering and thawing, and curing of wood and rubber products. Although there is extensive consumer and industrial use of microwave energy, interaction of microwaves with materials is poorly understood. Furthermore, there are numerous reports in the literature of non-thermal ‘microwave effects’ that accelerate reaction rates, alter reaction pathways and result in unique properties in polymers, ceramics and composites.