# Polymer-Derived SiOC Ceramics by Digital Light Processing-Based Additive Manufacturing
###### Abstract
Various additive manufacturing techniques have been documented, including stereolithography (SL) [21], inkjet printing (IJP) [22], fused deposition modeling (FDM) [23; 24], selective laser sintering (SLS) [25], digital light processing (DLP) [26; 27; 28], layered object manufacturing (LOM) [29], and direct ink writing (DIW) [30; 31; 32]. Table 1 presents a performance comparison and the preferred applications of the various 3D printing technologies that were discussed above for ceramic additive manufacturing. These techniques provide diverse capabilities for fabricating complex geometries and advancing manufacturing methodologies. They eliminate the need for molds and present significant advantages, such as high efficiency, a wide range of raw material options, and the ability to produce intricate and precise shapes [33]. Among these techniques, DLP, which employs the layered photopolymerization of light-curing resins, has been widely studied due to its maturity, cost-effectiveness, high molding efficiency, and excellent resolution. DLP printing has been successfully employed to fabricate ceramic samples with complex geometries, including honeycomb and porous structures, as well as materials for electromagnetic applications [34]. At present, the predominant approach for ceramic 3D printing involves processing ceramic powders into uniform, fine particles, incorporating binders and then, subsequently, printing and molding. The final step is sintering, which consolidates the ceramic model into its final form [35; 36; 37]. To achieve a high ceramic yield, enhance the density of the ceramic part, and minimize shrinkage during molding, it is necessary to increase the solids content of the ceramic powder, which can decrease the fluidity of the ceramic slurry and potentially result in printing failure [38]. Additionally, the particle size and inhomogeneity of the ceramic slurry limit its suitability for fabricating structures with fine feature sizes, thereby affecting printing resolution [39; 40]. Finally, ceramic particles are mixed with a liquid to create a solid-liquid slurry that is prone to settling over time. To mitigate this issue, an appropriate dispersant must be selected to maintain uniform dispersion, and the slurry should not be stored for prolonged periods. For ceramics with a high solid content, DLP technology may require additional preparation steps involving a non-ceramic powder-resin slurry route [41]. Integrating polymer-derived ceramic (PDC) technology with 3D printing provides an effective solution to these challenges [42]. PDCs eliminate the need for ceramic particles as raw materials, instead utilizing liquid polymers and resins. This approach mitigates issues related to solid content and viscosity, thereby addressing the problems inherent in conventional ceramic slurries [43]. PDCs are a precursor conversion ceramic technology in which organic polymer precursors (ceramic precursors) are synthesized through chemical methods and then converted into the target ceramics via high-temperature pyrolysis [44]. This process offers several distinct advantages: Firstly, PDC technology provides high design flexibility. The number and type of functional groups can be precisely controlled through molecular design, allowing for the molecular-level customization of the ceramic's composition, structure, and properties [45,46]. Secondly, PDCs can be prepared at relatively lower temperatures, typically between 1000-1400 \({}^{\circ}\)C, when compared to traditional ceramic methods such as solid-state synthesis or powder sintering, which require temperatures above 1500 \({}^{\circ}\)C [8]. Thirdly, PDCs do not require the addition of low-melting-point sintering additives. Their simple composition leads to fewer impurities, and fillers can be incorporated to introduce hetero-elements as needed [47]. Lastly, as polymer precursors, PDCs offer excellent processability and moldability, and they also exhibit good high-temperature creep resistance and stability [48].