Formulation development and optimization for printing ceramic (Silica and SiOC) based 3D structure through digital light processing

Abstract

Silica glass and silicon oxycarbide (SiOC) ceramics have prominent properties and have been widely used in various fields. With the development of technology, there is an increasing demand for ceramics with complex structures in fields such as optics and electricity. However, conventional fabrication methods are not suitable for manufacturing high-precision complex microstructures because of factors such as long processing times for internal structures, high cost caused by the fragility of ceramics, and much cracking caused by internal force. Owing to its high printing precision and the ability to print complex microstructures, digital light processing (DLP) has been employed for the manufacturing of silica glass and SiOC ceramics. Silica glass and SiOC ceramics are normally printed with dispersive and reactive slurries, respectively, in existing studies. Dispersive slurries possess high viscosity and slow photopolymerization reaction rates, which is difficult to print for commonly used lab based DLP system with LED light source. Reactive slurries are the opposite, but samples printed from reactive slurries are prone to gaseous by-products during pyrolysis, resulting in a less pure product than dispersive slurries. Therefore, this project aims to explore the preparation strategies and performance differences between these two formulations. In this project, a hydrophobic silica glass slurry with a solid loading of 27.5 wt% was successfully developed for DLP printing and the green bodies were sintered at 1100 ℃, 1200 ℃, 1300 ℃, and 1400 ℃, respectively. Although sintering was successfully triggered, cracks were observed, due to insufficient solid loading or inappropriate sintering program. On this basis, a slurry containing isobornyl acrylate with a solid loading of 40 wt% was identified as potentially printable. In addition, a SiOC-based formulation was successfully developed for DLP printing. In order to improve the stability of the SiOC slurry, multiple slurries with different formulas were placed under different conditions. A comparison of their viscosity changes revealed that air had the most significant effect on the viscosity of SiOC slurries.

Date of Award	13 Jul 2025
Original language	English
Awarding Institution	University of Nottingham
Supervisor	Yinfeng He (Supervisor) & Yi Nie (Supervisor)