EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

The use of electrical-discharge machining (EDM) in ceramics is an emerging topic, due to the difficulties found by conventional machining techniques to obtain small or complex shaped parts from hard and brittle bulk ceramics. EDM is widely used in metals due to its high accuracy and the hardness-independent machining speed. However, most ceramics are electrical insulators and therefore not ED-machinable, so the addition of an electrically-conductive second phase is required. The use of graphene nanostructures as a second phase in advanced structural ceramics enhances their electrical conductivity and enables the use of electrical-discharge machining in the composites. This work aims to assess the feasibility of EDM in advanced yttria-stabilized tetragonal zirconia (3YTZP) composites with graphene nanostructures. In particular, the influence of the type of graphene nanostructure used (size and number of layers) and the composite processing technique on the material removal rate will be evaluated. Moreover, the EDM surfaces of different composites will be characterized by confocal optical and scanning electron (SEM) microscopy, as well as by Raman spectroscopy. The presence of different phases, the structural integrity of the graphene nanostructures, the roughness of the machined surfaces and the geometrical tolerances of the technique on these materials will be assessed.