Three-dimensional printing allows extremely small and complex structures to be made even in small series. A method developed at the KIT for the first time allows also glass to be used for this technique. As a consequence of the properties of glass, such as transparency, thermal stability and resistance to acids, the use of this material in 3D-printing opens up manifold new applications in production and research, such as optics, data transmission, and biotechnology.
The scientists mix nanoparticles of high-purity quartz glass and a small quantity of liquid polymer and allow this mixture to be cured by light at specific points – by means of stereolithog-raphy. The material, which has remained liquid, is washed out in a solvent bath, leaving only the desired cured structure. The polymer still mixed in this glass structure is subsequently removed by heat-ing.
“The shape initially resembles that of a pound cake; it is still unstable, and therefore the glass is sintered in a final step, i.e. heated so that the glass particles are fused,” explains Rapp.
Complicated high-precision structures made of glass can be manufactured in a 3D-printing process developed at the KIT (Photo: KIT)
Glass is one of the most important high-performance materials used for scientific research, in industry and in society, mainly owing to its unmatched optical transparency, outstanding mechanical, chemical and thermal resistance as well as its thermal and electrical insulating properties. However, glasses and especially high-purity glasses such as fused silica glass are notoriously difficult to shape, requiring high-temperature melting and casting processes for macroscopic objects or hazardous chemicals for microscopic features. These drawbacks have made glasses inaccessible to modern manufacturing technologies such as three-dimensional printing (3D printing). Using a casting nanocomposite5, here we create transparent fused silica glass components using stereolithography 3D printers at resolutions of a few tens of micrometres. The process uses a photocurable silica nanocomposite that is 3D printed and converted to high-quality fused silica glass via heat treatment. The printed fused silica glass is non-porous, with the optical transparency of commercial fused silica glass, and has a smooth surface with a roughness of a few nanometres. By doping with metal salts, coloured glasses can be created. This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia.