REVIEWS DOI: 10.1002/adem.200500148 Gigahertz and Nanotubes – Perspectives for Innovations with Novel Industrial Microwave Processing Technology By L. Feher ,* M. Thumm and K. Drechsler 1. Introduction Of all the heating systems the electrically heated autoclave is today the most popular system for the high performance composite field, as prepregs usually need a high pressure en- vironment during the curing process for forming. Concerns on this state of the art approach are: – Long process times – Inherently energy inefficient system – Major difficulties caused by large thermal gradients and slow heat up times – Bag failures – Complex expensive tooling – High acquisition costs A special alternative for heating can be microwaves, since microwave heating at 2.45 GHz and 915 MHz has been estab- lished as an important industrial technology about more than 50 years ago. The successful application of microwaves in in- dustries, that always has to compete with conventional heat- ing systems, has been reported e.g. by food processing sys- tems, domestic ovens, rubber industry, vacuum drying etc. The use of microwaves shows new approaches on the pro- cess interaction, e.g. for the fibre materials, precursors, resin systems, lay-up preparation with direct consequences on the adjustable material properties. CFRP materials are heated 26 © 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim ADVANCED ENGINEERING MATERIALS 2006, 8, No. 1–2 – [*] L. Feher Forschungszentrum Karlsruhe GmbH, IHM D-76021 Karlsruhe, Germany E-mail: Lambert.Feher@ihm.fzk.de M. Thumm Universität Karlsruhe, IHE Kaiserstr. 12, D-76128 Karlsruhe K. Drechsler Universität Stuttgart Institut für Flugzeugbau, IFB Pfaffenwaldring 31, D-70569 Stuttgart, Germany A novel industrial microwave system HEPHAISTOS-CA2 (High Electromagnetic Power Heating Automated Injected Structures Oven System) for curing of carbon fibre reinforced plastics is being developed at Forschungszentrum Karlsruhe (FZK). The system is based on the HEPHAISTOS-CA1 prototype system at FZK which has been evaluated for the application in composite manufacturing together with EADS Corporate Research Centre and the Institute of Aircraft Design (University of Stuttgart). The system, which is in duty since the end of 2005 integrates advantageously the basic pro- cessing steps as tooling, tempering of the resin and lay up, the impregnation of the fibres, pre-forming techniques as well as finally the process curing of the composite structures.