Energy efficient microwave heating of carbon fibre reinforced plastic

During last decades an enormous growth of the aerospace market took place. Constant competition, growing demands on the efficiency of aircraft and more stringent safety requirements have initiated an unbroken development process, especially in the field of materials. Fiber reinforced plastics is a group of innovative lightweight materials, their use can increase the performance of the aircraft and can satisfy the social need for energy efficiency. The polymerization of carbon fiber reinforced thermosetting composites (CFRP) is a dull process step with high energy requirements within the production chain. His improvement would affect the economic and ecological balance of the fiber reinforced materials in a positive way. One possible approach investigated in this work is tempering of raw materials in a microwave oven. In this case, the required energy is provided not by forced convection, but by an external microwave field. The field energy is converted directly and exclusively in the process material into thermal energy. This concept leads to energy pathways that are fundamentally different from those of a convection-based process, but it also poses new demands on manufacturing equipment. The knowledge of energy pathways and the energy balance within the microwave-based process opens up new possibilities to manipulate them so that the energy efficiency of a tempering process can be increased significantly. In this work the material to be processed - a carbon fiber-reinforced plastic laminate - is being characterized in the microwave field through electromagnetic and thermal parameters. The relationship between its design parameters (fiber orientation and number of layers), the energy levels (reflection, absorption and transmittance) and the thermal process parameters (temperature gradient achievable) will be established. Afterwards, constructive options will be examined and evaluated which are suitable to install a low-loss (both by means of wave reflections and heat losses) industrial process.