On microwave discharge machining of ceramics

The combined action of a microwave electric field and focused laser radiation on dielectrics is studied with the purpose of developing a discharge technique for the machining of certain kinds of dielectrics, e.g. ceramics. The idea of the machining is based on the phenomenon of enhanced absorption of microwaves by dielectrics preheated locally by some additional heat source. Theoretical analysis shows that, due to this effect, the destroyed zone at the dielectric surface can be more narrow than the preheated region. The idea was tested on samples of pink alumina in a microwave cavity using an electric field with wavelength /spl Lambda/=12.5 cm. Experiments on laser beam heating of dielectrics simultaneously with microwave irradiation revealed a pronounced cooperative effect of material removal.