Electrical discharge machining of non conductive advanced ceramics Zusammenfassung: Characterized by excellent material properties such has high mechanical thermal and chemical stability advanced ceramics such as ZrO2 SiC Si3N4 and AlN are increasingly used for various applications. Traditional means of machining sintered ceramics are expensive and the structure formed using them are limited in accuracy and geometry. Electrical discharge machining (EDM) is an electro thermal machining process used to structure conductive materials. By applying a conductive layer (denoted as assisting electrode (AE)) on top of the non conductive material the EDM process can also be used to structure non conductive ceramics. The EDM process starts with a discharge taking place between the tool electrode and the assisting electrode. During the process carbon particles that are secreted from the dielectric oil are deposited on the newly exposed non conductive ceramic surface forming a thin conductive layer. This intrinsic conductive layer (ICL) insures that the electric contact between the workpiece and the generator is maintained. After the machining process the conductive layer can easily be removed for instance by heating. However the fundamental conditions required for the formation of the ICL and the underlying material removal mechanism of the µ EDM of the non conductive ceramics using AE is not fully understood