Microwave Assisted Materials Processing Activities at KIT and Latest Research Results

The Karlsruhe Institute of Technology (KIT) is one of the largest research and education institutions in Germany. KIT is pursuing the mission of a university and the mission of a research institution of the national Helmholtz association with programmatic provident research on behalf of the Federal Republic of Germany. Within this framework, the Institute for Pulsed Power and Microwave Technology (IHM) is conducting applied research and development in the field of materials processing with microwaves. As a spin-off from nuclear fusion research activities, high power gyrotrons, used for plasma heating in fusion reactors were applied for high temperature processing of materials such as technical ceramics, glasses and metal powder compacts, starting 25 year ago. Since that time, those activities have been continuously expanded to novel applications, such as curing of fiber-reinforced plastics (FRPs), pultrusion, 3D printing and others, by use of industrial microwave sources.
For a successful processing of large size FRP materials, which face growing demand from avionics and automotive industries, large furnaces with excellent electromagnetic (EM) field homogeneity and a curing in properly defined temperature limits are pre-requisites. ... mehrSo far, both, the requirement on accurate temperature control and the requirement on uniform EM field distribution were the major limiting factors for the breakthrough of microwaves in this and other fields of applications. The KIT patented polygonal applicator design, named HEPHAISTOS offers best possible EM field distribution. Moreover, due to the modularity of that concept, it can be scaled up to the size required. So far, different HEPHAISTOS microwave systems with process volumes up to 7.5 cubic meters are available for industrial process developments. In meantime, the technology is licensed to and is further under development with the industrial partner Vötsch Industrietechnik, Reiskirchen, Germany. A survey of these and other microwave related developments and latest research results will be presented.