Gigahertz and Nanotubes – Perspectives for Innovations with Novel Industrial Microwave Processing Technology

Abstract

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 processing 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.

Microwave pre‐oxidation for polyacrylonitrile precursor coated with nano‐carbon black

“…The main operating frequencies are 915 MHz and in the majority 2.450 GHz . Microwave field infiltrates the material and works as an instant heating source at each point of the structure . It can reduce processing times , increase product yields, and enhance product purities over that reported for conventionally processed experiments .…”

Microwave curing of epoxy polymers reinforced with carbon nanotubes

“…Alternatively, microwaves (MWs) have been proposed for heating and curing to produce polymeric composite parts. The driver for the application of MW technology to composites is the reduced energy needs for the manufacturing and the process time owing to increased energy efficiency, the lower investment costs,5 and the application scale 1…”

“…The principles of MW heating for curing polymers6 and composites7, 8 have been developed and described more than 20 years ago. More recently, MW has been evaluated in several studies as an alternative curing method for the production of composite components on an industrial scale 1, 5. The advantage offered by MW heating technology is the generation of heat from within the composite with less power input.…”

“…To this end, customization of curing reaction rates has been proposed as the key parameter for this transfer 12. Nevertheless, only the past decade developments in MW technology have made it technically and economically possible to apply MW curing to composites in an industrial scale5 although it has been used in other industries for much longer 6, 13…”

“…To tackle these issues, the use of fillers as susceptors in the polymer has been proposed 12, 15. Research in the area of nanotechnology has delivered various nanofillers that represent promising additives toward the direction of MW curing 5, 12, 16. Some studies have reported on the combined use of MWs and carbon nanofillers (carbon nanofibers17 and carbon nanotubes [CNTs]18), thanks to the excellent MW‐absorbing properties of carbon structures 19.…”