Mechanical properties and processing of ceramics and metals. Current interests include processing and properties of ceramic nanocomposites, the use of carbon nanotubes and graphene in ceramic composites, mechanical testing and stress measurement in ceramics at the microscale, high strain rate performance of ceramics for armour applications, "flash sintering" of ceramics, probing of stress and structure using neutrons and synchrotron radiation, improved metal forming for automobiles and mechanisms of superplastic deformation.
Ultra-fast and energy-efficient sintering of ceramics by electric current concentration.
Zapata-Solvas, E, Gómez-García, D, Domínguez-Rodríguez, A, Todd, RI
Electric current activated/assisted sintering (ECAS) techniques, such as electrical discharge sintering (EDS) or resistive sintering (RS), have been intensively investigated for longer than 50 years. In this work, a novel system including an electrically insulated graphite die for Spark Plasma Sintering (SPS) is described, which allows the sintering of any refractory ceramic material in less than 1 minute starting from room temperature with heating rates higher than 2000°C/min and an energy consumption up to 100 times lower than with SPS. The system alternates or combines direct resistive sintering (DRS) and indirect resistive sintering (IRS). Electrical insulation of the die has been achieved through the insertion of a film made of alumina fibers between the graphite die and the graphite punches, which are protected from the alumina fiber film by a graphite foil. This system localized the electric current directly through the sample (conductive materials) as in DRS and EDS, or through the thin graphite foil (non-conductive materials) as in IRS, and is the first system capable of being used under EDS or RS conditions independently combining current concentration/localization phenomena.