Additive manufacturing of carbon fibre-reinforced thermoset composites via in-situ thermal curing

Paper Overview

This study reports a tool-free, energy-efficient process to 3D-print carbon fibre-reinforced thermoset composites (FRPCs) by curing the thermoset in situ during deposition. A thermoresponsive resin system is paired with local photothermal heating of the carbon fibres so that parts rigidise immediately, eliminating moulds, support structures and oven post-curing—historic bottlenecks for thermoset composite AM. (Dojan 2025). Nature

Methodology (objective)

• Resin chemistry: A rapid-curable ROMP system (DCPD→pDCPD) is tuned for viscosity and cure kinetics compatible with direct-write deposition.
• Photothermal cure: Carbon fibres act as embedded heat sinks; laser-induced photothermal conversion cures the matrix as it is laid down.
• Fibre formats: Demonstrations span discontinuous and continuous carbon fibres, including mid-air features (unsupported trajectories).
• Process characterisation: The team maps laser power density, print speed and tow size against path fidelity, void content and fibre volume fraction. (Dojan 2025; PubMed record). NaturePubMed

Key Findings

• Tooling and post-cure removed: The process dispenses with moulds and ovens, collapsing cycle time and capital needs for many FRPC parts. (Dojan 2025). Nature
• Geometric freedom: Immediate rigidisation enables unsupported geometries and precise fibre steering that are difficult with melt-processed thermoplastics. (Dojan 2025). Nature
• Materials quality indicators: Reported builds achieve high fibre volume fractions with low voids (order of ~0–1.5 vol% in exemplars), indicating sound consolidation for a rapid process. (Dojan 2025). Nature
• Generalisation potential: The authors argue the photothermal approach is matrix-agnostic across rapid-curable thermosets and adaptable to different thermal stimuli. (Dojan 2025). Nature

Critical Appraisal

Strengths

• Targets the right constraints: By removing support structures, tooling and oven cures, the method squarely addresses time-to-part and cost drivers that have limited thermoset AM. (Dojan 2025). Nature
• Versatility: Compatibility with both continuous and short fibres plus mid-air printing meaningfully expands the design space. Nature
• Mechanistic clarity: The ROMP chemistry and photothermal coupling are well-motivated and experimentally probed, lending credibility to scaling discussions. Nature

Limitations

• TRL and qualification gaps: The paper establishes feasibility but does not present full-scale qualification (fatigue life, environmental ageing, repairability, NDI protocols). Adoption for safety-critical domains will require that evidence. (Reasoned inference based on certification norms; not a claim made by the authors.)
• Process control & safety: Industrial deployment will need robust laser-safety interlocks, thermal-history-aware toolpaths, and in-process monitoring to keep voids and fibre alignment within limits. (Reasoned inference from the setup described.)
• Materials scope: Results centre on pDCPD; translation to epoxy/benzoxazine/urethane systems remains to be proven for universal applicability. (Reasoned inference.)

6.4 Practical Implications for the 3D-Printing Ecosystem

• Faster custom FRPCs: Expect shorter lead times for jigs, fixtures, tooling aids and bespoke structural components where moulds are currently the bottleneck.
• Capex shift: Reduced spend on moulds/ovens with a reallocation towards robotic deposition plus photothermal modules.
• Design latitude: Enable freeform continuous-fibre steering and unsupported features, potentially improving stiffness-to-weight without excessive build supports.
• Early production niches: Field repair, on-site fabrication, and low-volume/high-complexity FRPCs look like near-term winners while broader material/qualification work matures.
• (All points derive directly from or are consistent with the capabilities and constraints reported by Dojan 2025.) Nature

Dojan, C. F., Ziaee, M., Masoumipour, A., Radosevich, S. J., Yourdkhani, M., et al. (2025). Additive manufacturing of carbon fibre-reinforced thermoset composites via in-situ thermal curing. Nature Communications, 16, 4691. https://doi.org/10.1038/s41467-025-59848-2.