Effective post-cleaning strategy for vat photopolymerization 3D printed complex-structured polymer-derived ceramics

Achieving ideal surface quality and high structural integrity of complex-structured polymer-derived ceramics manufactured by vat photopolymerization 3D printing not only depends on the high temperature pyrolysis processing, but also greatly relies on the complete removal of uncured resin on the surface and internal holes of the green bodies before pyrolysis. In this work, based on the characteristics of precursor resins and printed bodies, a novel cleaning strategy with excellent cleaning efficiency and the corresponding cleaning agent with good flowability, appropriate solubility, and strong volatility are proposed. The cleaning agent consists of two monomers, butyl acrylate (BA), and 1,6-hexanediol diacrylate (HDDA), which are components of the precursor resin, thereby avoiding chemical reactions between the cleaning agent and the printed bodies. Meanwhile, by adjusting their proportions, suitable solubility and volatility are achieved. Appropriate solubility ensures that under diluted conditions, it does not damage the cured resin, while strong volatility removes the diluted uncured resin in a short time. Additionally, good flowability enables thorough penetration into the internal holes to mix with and contact the uncured resin. This cleaning process achieves efficient and high-quality cleaning of ceramic precursor 3D printed bodies. The superiority of this strategy is confirmed by observing and characterizing the pyrolyzed samples. It achieves high surface quality, structural fidelity, and no crack defects, with 100 % opening of 150μm diameter holes, high through-hole rates, low surface roughness, and peak-to-valley height. In contrast, traditional cleaning processes have lower through-hole rates, higher roughness, and suffer from structural distortion and cracks. Thus, the proposed post-cleaning strategy provides a guidance on the design and selection of cleaning agents and methods for effective cleaning of these ceramic samples derived from similar ceramic precursors.