Robocasting of 3D-ceramic macrocellular structures with tubular filaments

• Applicant: Professor Dr.-Ing. Nahum A. Travitzky
• Subject Area: Glass, Ceramics and Derived Composites
• Term: from 2012 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 231507867

The proposed project focuses on the investigation of material-specific principles of the robocasting-process. The main goal of the proposal is to develop novel gel-systems loaded with Al2O3, SiC und Si3N4 for additive manufacturing of complex 3D-structures. The methodical novelty is the application of tubular filaments of various cross-sections, which require special high-viscosity-gels and extruder-nozzle. The investigation concentrates on the deformation of the filaments while deposition, which is predominately determined by external forces and rheological characteristics such as viscosity, shear-elastic-modulus and yield-stress. For highly viscous gels the study of the rheological behavior is of crucial importance; the latter is strongly influenced by the flow-profile within the extruder-nozzle, where wall slip and plug flow are likely to occur. A further objective is to diminish the deformation of the filaments due to external forces (gravity, under-pressure in the capillary) to achieve near-net-shape capability. Furthermore a high solids content (> 50 vol%) of the gels shall be attained to induce a low drying-shrinkage. Static and dynamic models for shape-evolution while extrusion shall be verified and adapted to tubular filaments, It is important to elaborate the differences between structures composed of tubular filaments compared to structures composed of massive filaments concerning mechanical properties. In addition, the mechanical properties of ceramic 3D Structures shall be simulated using FEM based on mechanical properties of single sintered filaments.

• DFG Programme: Research Grants
• Major Instrumentation: Rheometer
• Instrumentation Group: 1610 Viskosimeter, Rheometer