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

In the last decade, the scientific community has tried to overcome the low strain failure of metastable tetragonal zirconia by introducing graphene-based nanomaterials (GBN). However, the difficulty in achieving a good dispersion of the reinforcement into the matrix still represents a brake on improving the mechanical properties. Moreover, owing to the nature of these composite ceramics, their final properties extremely depend on their microstructure. For example, fracture toughness values for GBN-3Y-TZP composites found in the literature range from 0.6 to 6.0 MPa·m^1/2. Therefore, an in-depth study of the microstructure should be systematically addressed and correlated with the resulting properties to fully understand the reinforcement mechanisms involved.

In this work, fully dense 3Y-TZP composites containing commercially available few layered graphene (FLG) were consolidated by Spark Plasma Sintering (SPS) from optimized dispersed powders through different wet processing routes. The microstructure of the resulting materials was characterized by using Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X ray diffraction (XRD) in order to assess the 2D graphene nanosheets integrity, their degree of dispersion into the matrix and the stabilization of the tetragonal phase in 3Y-TZP. Finally, some mechanical properties (hardness, elastic moduli, fracture toughness, strength, crack growth resistance...) and the Low Temperature Degradation (LTD) of different FLG/3Y-TZP composites were studied and correlated to the microstructural features.