Zirconia-based ceramics are widely used in structural and functional applications owing to their excellent mechanical properties, good ionic conductivity and high temperature stability. The addition of carbon-based materials, such as graphene nanoplatelets, has demonstrated to have a beneficial effect on the tribological behavior of these composites by decreasing both the friction coefficient and the wear rate. These improvements are attributed to the presence of a protective tribolayer adhered to the worn surface.

In order to further explore the effect on the wear behavior of yttria-tetragonal zirconia polycrystals (3Y-TZP) – graphene materials, composites with different vol.% few layered graphene - FLG - (1, 2.5, 5 and 10 %) were prepared by ultrasonic agitation and spark plasma sintered at 1250 ?C. The tribological behavior of these composites was studied using a ball on disc configuration at room temperature. The tests were carried out using normal loads of 5 and 10 N and a sliding speed of 0.1 m/s at ambient air (40-60% relative humidity, room temperature) on polished surfaces. Surfaces were analyzed using confocal and scanning electron microscopies, and Raman spectroscopy.

Composites show lower friction coefficient and wear rates when compared to the monolithic sample. Among all the composites, 2.5 vol.% FLG - 3Y-TZP show an overall better performance, with a friction coefficient of 0.4 and a wear rate of 10-6mm3/Nm for tests carried out at 10 N normal load. This is a reduction of 50% in the friction coefficient and more than one order of magnitude on the wear rate when compared to the monolithic samples tested under similar conditions. All these results will be discussed and correlated with confocal and high-resolution scanning electron microscopy images, and Raman spectra of the tracks originated during friction tests.