Additive manufacturing of advanced silicate ceramics by means of two-photon polymerization

• Applicant: Dr.-Ing. Enrico Storti
• Subject Area: Glass, Ceramics and Derived Composites ; Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527057757

The goals of this project are to develop suspensions from preceramic polymers with nano-sized ceramic powders as fillers, and to fabricate advanced silicate ceramic components by two-photon polymerization (TPP) from such suspensions. The main target composition will be mullite, which can be obtained by the reaction between nano-sized gamma-alumina and amorphous silica from the pyrolysis of the preceramic polymer (e.g. a commercial, solvent-free acrylate siloxane). The photocurable resins will be investigated in terms of rheology and transparency and the best suitable compositions for TPP will be selected for printing. Differential scanning calorimetry coupled with thermogravimetry will be performed to find the critical temperatures for debinding and sintering. Objects of small size (<1 mm3) and high complexity will be fabricated using a 3D printer designed for TPP technology. Writing parameters such as layer thickness, hatch distance, scan speed and laser power output will be adjusted in order to maximize speed while keeping a high resolution of the printed parts. After washing and drying, the debinding and sintering processes will be investigated to minimize the shrinkage and shape distortion. The final components will be fully investigated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy to obtain information on the microstructure and chemical composition. In addition, the phase composition of the parts after sintering in air will be determined by X-ray diffraction. Samples with simple geometry and larger sizes (e.g. 1 cm3) will be manufactured specifically for mechanical testing using the same printer and compositions in one-photon polymerization mode, adjusting the photoinitiator if required. Finally, the most promising compositions will be modified with ceramic nano-sized powders of different compositions and refractive indices. The impact of fillers such as zirconium oxide, calcium oxide and yttrium oxide on the suspension properties and on their suitability for TPP will be assessed, and printing experiments will be performed with the best candidates.

• DFG Programme: WBP Fellowship
• International Connection: Switzerland
• Host: Professor Dr. Thomas Graule