Experimental Verification for Microwave Processing of Materials in a Single Mode Rectangular Resonant Cavity

Abstract

The benefits of applying microwave energy to material processing techniques have been well documented and studied. The potential benefits over conventional oven heating include faster processing times, more uniform heating, more consistent product quality, and the possibility of precise control.

The actual implementation of microwave technology has been lacking and the benefits have gone largely unrealized. This is due in part to the temperature dependence of the dielectric loss of many industrial materials such as ceramics and polymers. These materials absorb more microwave energy as they heat, creating uncontrollable heating, often called 'thermal runaway'. The focus of this research is to address this challenge.

The work described here is an experimental program for the microwave processing of specific ceramic rods and polymer tows. The objective of the program is to study the thermal runaway effect, and to provide data which will be used to verify numerical models. Accurate test data are essential to the development of precise, comprehensive models that can be used in applicator design and heating control strategies for thermal runaway materials. The experimental program explores the difficulties of microwave heating and offers solutions to more efficient systems. Successful measurements of power loss and control of thermal runaway are detailed for mullite, alumina, and nylon.