Microwave firing of heavy clay bodies: the examination of the key variables, which influence the microwave heating process

摘要

The paper reports on recent research work carried out in the ESCOM, TRI Laboratories in Johannesburg, South Africa, in collaboration with the Microwave Processing Group Laboratories, at the School of Engineering and Advanced Technology, Staffordshire University, England. Extensive mineralogical, thermal, chemical and physical analyses were carried out on the raw materials and the body compositions that were used in the research work. The resultant findings provided the basis for the selection of the optimum body compositions used for the microwave firing tests. A suitable carbon additive was used to alter the dielectric properties of the test bodies. The design features of the hybrid cavity, used to conduct the test firings, are described. The key variables that influence the microwave heating process were identified and examined. The methodology incorporated the use of various techniques of forward power application. Observations of resultant reflected power levels were made. The influence of the surface area of the test pieces and the application of secondary air supply to the cavity, were found have a crucial influence on the heating process. The paper further examines the technology transfer potential of the work and considers the feasibility of using a hybrid microwave energy system for the firing of heavy clay products.