MICROWAVE APPLICATIONS IN MATERIALS JOINING

This paper discusses pioneering work and developments in the area of m icrowave applications into materials welding and joining. In particula r, the various microwave techniques for welding metals using microwave induced plasma jet, and joining polymers and ceramics: utilising elec tromagnetic field focussing facilities are detailed. The employment of microwaves for fast curing adhesives for joining transparent to micro wave radiation materials is also explained. Both autogenous and hetero geneous materials welding and joining applications are outlined togeth er with the mechanisms and heat transfer phenomena taking place during the bonding process. While relatively low dielectric loss materials a re joined using bonding agents susceptible to microwave radiation for wetting the surfaces to be fused, high dielectric loss materials are d iffusion bonded resulting in high bond to parent material strength rat io. In the latter case, generated heat is dissipated into the fusion z one volumetrically and the joining process does not rely on conduction heating from the surface, as in the former case. Future research dire ctions for further developments are also discussed in the paper and co ncluding remarks point to the encouragement of more efforts in this ne w field of materials processing using microwaves.