Theory and application of microwave joining

Microwave processing of materials is advancing from a novel processing technique into a viable method for processing industrial materials. It has been adopted by several industries for the following reasons. Microwave processing can afford savings in energy or space or, more importantly, it can provide a product with qualities that cannot be achieved through conventional means. Even as the use of microwave processing increases in industry, it is vigorously investigated by researchers attempting to better understand and control the mechanisms that are responsible for microwave heating of materials. These investigators are seeking evidence that can either demonstrate or disprove the concept of enhanced microwave processing. Simultaneously, researchers also are looking for innovative techniques that can provide other industrial applications for microwaves.;Joining has always been an integral component of the manufacturing industry. The joint is often the weakest link of any manufactured item and researchers are continually pursuing means of increasing the strength of the joint. Several ceramics have been joined successfully using microwave energy. However, there are no processing guidelines available so the data that have been generated cannot be easily compared. Furthermore, much of the previous work reports the condition of the joint qualitatively, making comparisons of joining procedures nearly impossible.;The research performed in this study attempts to address many of the issues discussed above. The main goal of this research is to join alumina using microwave energy and to develop an understanding of the microwave interactions with materials and its relation to the joining process.;An apparatus for the microwave joining of materials was designed and put into use. A procedure for producing susceptors for microwave hybrid heating was developed. Using the microwave joining apparatus and hybrid heating, high-purity alumina was joined using several materials as the interlayer between the alumina end members. An experimental design was used to provide data that then could be analyzed statistically to determine the significance of the processing parameters varied during joining. A numerical model simulated the microwave heating of the joining process. Simulated temperature profiles were compared to experimentally measured temperatures to assess the usefulness of the model.