Nowadays the use of microwaves for heating is familiar to anyone due to the domestic microwaves operating at 2.45 GHz. It is advantageous that the heat is generated inside the material volume, so the heating is quick, direct, and energy efficient. In particular, materials characterized by low thermal conductivity such as plastics, glass, ceramics and powders can be heated much faster. In the technical material process technology these advantages are opposed by problems also known from domestic microwaves: Heat distribution may be inhomogeneous, and the microwave penetration of some materials is insufficient, while others are more transparent to microwaves and hardly can be heated.
At the IHM solutions to such problems were investigated for both the industrial microwave frequency 2.45 GHz and in the millimeter wave range. This includes the determination of process parameters and product quality in comparison to conventional heating. Thus, microwave heating proves to be faster, more energy efficient and sometime allows for a reduction of the process temperature. Hence, in many cases the properties of the microwave processed materials can be improved, as it was shown, for example, for carbon fiber reinforced plastics (CFRP) and various ceramics.