Anagrafe della ricerca

The production of strong yet tough ceramics is particularly relevant for the biomedical and aerospace sectors, where the achievement of metal-like reliability still represents a holy grail. Ceria-stabilized zirconia (Ce-TZP) has been extensively studied due to its ability to undergo larger amount of stress-induced phase transformation, which leads to higher fracture toughness than Yttria-stabilized zirconia (Y-TZP), due to its ability to initiate stress-induced t-m phase transformation at lower stresses. In contrast, Ce-TZP materials develop a lower mechanical strength in comparison with Y-TZP, and to overpass this drawback complex, multiphase Ce-TZP-based nanocomposites can be produced. However, the mechanisms regulating crack nucleation and propagation in these nanocomposites are still unclear, and fundamental research efforts are needed. CONCERTO will develop a suite of harmonized multiscale materials modelling and characterization methods, to support and accelerate the production of Ce-TZP nanocomposites and coatings, with unprecedented combination between strength and toughness. Within CONCERTO, three strategies to increase crack propagation resistance will be investigated by using integrated modelling/characterization techniques: (i) phase transformations in front of the crack tip, (ii) second phase toughening and (iii) grain boundary engineering. To investigate such mechanisms, advanced micro-nanoscale characterization methods will be developed and validated, in direct comparison with a novel Phase-Field Method (PFM) for Finite Element Modelling of the microstructural effects on crack nucleation and propagation. A multi-scale design of selected ceramic components will be performed, to demonstrate the ability to engineer the materials from the nano/microstructural features to the macro-structure, and through all processing ceramic steps, from composite powder elaboration, to shaping and sintering of the final parts. An emerging 3D printing technology for technical ceramics,stereolithography, will be used for the first time to fabricate simple and complex-shaped demonstrators, in parallel with the exploitation of thermal spray technology to fabricate coatings. Finally, two impactful case studies are selected to demonstrate the relevance of the research conducted, namely optimization and functional validation of (a) Ce-TZP materials for application in dental prostheses and (b) Ce-TZP composite thermal barrier coatings for high-temperature applications. To achieve such ambitious goals, a multi-disciplinary coordination activity will be established, linking reference characterization laboratories in Italy with capacities on advanced multi-technique microstructural/nanomechanical analysis (UniRoma3), to reference groups on multiscale modelling of fracture (UniUD), product manufacturing (PoliTo, UniMore), and industrial exploitation of ceramic nanocomposites for biomedical and aeronautical applications (PoliTo, UniMore, UniTo).