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Material extrusion is a very common and facile additive manufacturing technique for ceramic materials, allowing for rapid design and fabrication of 3D structures without expensive tools. However, fabricating sophisticated structures with large spanning parts and overhanging features using this technology is still a challenge. Here, UV-assisted additive manufacturing is enabled by performing material extrusion with the assistance of UV light using mixture of a preceramic polymer and a photopolymer. The rheological properties of the ink were investigated under UV light radiation to optimize the printing parameters to achieve excellent printability. Complex ceramic structures were fabricated with this method, such as spiral and truss structures, which would be very difficult to obtain using traditional material extrusion without sacrificial supports. These structures have potential application in lightweight ceramic components, such as sandwich structures.

The extensive study and development of additive manufacturing technologies have allowed not only increased customization of the final parts but especially of their complexity. From such perspectives, intricate and mechanically efficient lattices which maximize their strength-to-weight ratio could be printed. Nevertheless, the fabrication of regular lattices, like octet cells, has been proven to be particularly limited by the layer-by-layer construction process due to the introduction of additional interfaces and/or the requirement of supports. In this work, a hybrid extrusion–photopolymerization process is coupled with a 6-axis robotic arm to allow for the fabrication of layers-less lattices thanks to the use of a custom graphical user interface and control over the printing head orientation. A highly reactive resin is employed as the ink and loaded with silica particles in order to tailor its rheological properties. A good resemblance between the printed components and the digital model is achieved, while their mechanical properties are superior to the ones of the traditionally additive manufactured octets.

Additive manufacturing of ceramic and glass materials has been developed extensively over the past years, revealing strengths and limitations of the various technologies. In this work, a hybrid extrusion-photopolymerization process is developed to exploit the benefits of both approaches. Their combination allows for more complex geometries with less rheological constraints and no influence of scattering and/or absorption. With this method, transparent silica glass 3D honeycomb-like structures are fabricated starting from a suspension that combines silica particles and a silicon alkoxide. The rheological behavior and reactivity of the ink are tailored with an appropriate blend of acrylates as well as with the alkoxide addition. The latter also contributes to the final ceramic yield, allowing for faster thermal treatments despite a low particle loading. The final components closely match the shape provided by the CAD model; their physical properties confirm the formation of a fully dense silica glass after the heat treatment.