3D printing combining extrusion Coupled moulding process advances ceramic 3D printing

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A new coupled moulding approach could help overcome key limits in ceramic 3D printing by combining extrusion with in-situ UV curing, enabling more stable production of high-precision, complex polymer-derived ceramic components.

Researchers propose a novel process paradigm of photopolymerization-extrusion coupled moulding targeting the 3D printing of polymer-derived ceramics (PDCs). Their work investigates multi-type ceramic precursors, photopolymerization mechanisms, volume shrinkage behaviours and rheological properties of printable slurries, effectively addressing the long-standing industry challenge of balancing high precision and low defect rates in conventional printing technologies. Integrating the strengths of extrusion moulding and photocuring, this technology offers an innovative route for the additive manufacturing of high-performance ceramic components with complex geometries for aerospace, energy, biomedicine, electronics and other fields. The findings offer significant theoretical value and promising prospects for industrial application.

Advanced ceramics have become indispensable core materials in aerospace, new energy, biomedicine, electronic devices and other fields due to their exceptional properties such as high hardness, excellent high-temperature resistance and superior corrosion resistance. Nevertheless, the inherent brittleness of ceramics restricts conventional forming technologies to fabricating only simple structural parts, which greatly limits their application scope. Three-dimensional (3D) printing, or additive manufacturing, has emerged as a mainstream technology for near-net shaping of ceramics. Among various material systems, polymer-derived ceramics (PDCs) have attracted extensive research attention by virtue of binder-free characteristics, customizable molecular structures and low-temperature ceramization capability.

However, standalone photocuring and extrusion-based 3D printing technologies each have inherent limitations. Photopolymerization relies on low-viscosity slurries, making it challenging to process precursors with high solid content. Pure extrusion moulding frequently suffers from filament collapse, weak interlayer bonding, warpage, cracking and insufficient dimensional accuracy. The contradiction between forming precision and manufacturing defects has long hindered the large-scale fabrication of high-performance ceramic components.

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To break through this industrial bottleneck, researchers have innovatively proposed a photopolymerization-extrusion coupled moulding technology. This integrated system realizes synchronous extrusion deposition and in-situ ultraviolet (UV) curing, reshaping the development landscape of 3D printing for ceramic precursors. Different from the conventional two-step mode of post-extrusion curing and layer-by-layer separate curing, the ceramic precursor slurry is continuously extruded through a nozzle into filaments, which are rapidly cured and instantly shaped by coaxial or para-axial UV light upon extrusion. This mechanism fundamentally inhibits deformation and collapse, enabling stable layer-by-layer deposition.

The research team systematically reviewed the development of binary, ternary and multi-component composite ceramic precursor systems. Binary systems represented by silicon carbide (SiC) lay the foundation for PDCs. Ternary systems including SiOC, SiCN and SiBN greatly improve the high-temperature stability and oxidation resistance of materials. Quaternary and multi-component systems such as SiBCN and SiOCB further raise the maximum service temperature beyond 2000 °C, meeting the requirements of extreme service conditions. Meanwhile, three major photopolymerization modification strategies were summarized: grafting photocurable functional groups, blending two-component oligomers, and constructing multi-functional acrylate composite systems. The forming precision, ceramic yield, shrinkage rate and applicable scenarios of different strategies were compared, providing a systematic theoretical basis for the molecular design of precursor formulations.

Volume shrinkage is the primary cause of internal stress, cracking and dimensional deviation in photocurable ceramic printing. This study thoroughly elaborated the molecular mechanism of photopolymerization and the origin of shrinkage. Based on the linear shrinkage, volume shrinkage and ceramic yield data of mainstream ceramic systems including SiC, SiOC, SiCN and SiBCN, three effective strategies to mitigate shrinkage were proposed: selecting low-shrinkage monomers, utilizing ring-opening compensation of cyclic monomers, and modifying with functional fillers, which significantly alleviate various forming defects induced by curing shrinkage.

Coupled moulding improves precision and process stability

In terms of forming processes, the power-law model and Herschel-Bulkley rheological model were established based on the non-Newtonian fluid theory to accurately characterize the shear-thinning behavior of ceramic precursor slurries. The flow regime of extrusion was determined via Reynolds number, and the control criteria for laminar flow were clarified. The influences of nozzle structure, wall slip, extrusion pressure and flow rate on filament uniformity were also analyzed. Furthermore, a synergistic optimization system integrating slurry formulation, light source parameters and environmental conditions was established. By regulating light intensity gradient, exposure energy and curing depth, the team balanced curing rate and internal stress, and remarkably enhanced interlayer bonding strength and overall structural stability of printed parts.

Compared with traditional single-mode 3D printing technologies, photopolymerization-extrusion coupled moulding presents prominent advantages. It retains the superior processability of extrusion technology for high-viscosity precursors with high ceramic yield, while inheriting the high precision and good surface quality of photopolymerization. In-situ photocuring greatly improves the manufacturability of overhanging structures, reduces the use of support structures and minimizes cracks caused by heterogeneous stress accumulation. Additionally, this technology weakens oxygen inhibition of polymerization and further elevates the production yield.

At present, the material systems, reaction mechanisms, rheological behaviors and core principles of the coupled moulding technology have been fully clarified. For future industrialization, the team put forward four key development directions: implementing molecular engineering design of low-shrinkage and high-performance precursors; establishing multi-physics coupling simulation models covering fluid flow, light propagation, reaction kinetics and thermal diffusion; realizing in-situ intelligent closed-loop control by combining high-speed imaging, sensors and machine learning algorithms; and developing large-scale, high-throughput integrated industrial equipment.

This study establishes a complete theoretical and technological framework for photopolymerization-extrusion coupled moulding, and completes the key technical chain from material design and process optimization to practical application of high-performance PDCs. It not only drives ceramic additive manufacturing toward higher precision, fewer defects and better stability, but also delivers novel solutions for the fabrication of high-end components, such as high-temperature ceramics for extreme environments, biomedical ceramics, functional catalytic ceramics and microelectronic packaging ceramics. The achievements will facilitate technological upgrading and application expansion of the advanced ceramic industry.

Original Article: Photopolymerisation-extrusion coupled moulding: a new paradigm and trend outlook for 3D printing of ceramic precursors; Advanced Equipment; DOI:10.55092/ae20260003

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