Glass remains one of the most challenging of all materials that can be printed in 3D. But scientists at the ETH Zurich research centre in Switzerland are working to change that with a new and better glass printing technology.
Printing glass objects is now possible, and the most common method involves either extruding melted glass, or selective sintering (laser-heated) ceramic powder, which is converted into glass. The former requires high temperatures and therefore requires heat-resistant equipment, while the latter cannot produce particularly complex objects. ETH’s new technology aims to improve these two disadvantages.
It contains a photosensitive resin consisting of liquid plastics and organic molecules that bond with silicon-containing molecules, in other words, ceramic molecules. Using an existing process called digital light treatment, the resin is exposed to the pattern of ultraviolet light. Plastic monomers are cross-linked to form solid polymers wherever the light hits the resin. The polymer has a maze-like internal structure, and the space inside the maze is filled with ceramic molecules.
The resulting three-dimensional object is then burned at a temperature of 600oC, burning the polymer, leaving only the ceramic. In the second roasting, the roasting temperature is about 1000oC, and the ceramic is compacted into transparent porous glass. The object does shrink significantly when converted to glass, which is a factor that must be taken into account in the design process.
Although the objects created so far are small, the shapes are rather complex, the researchers said. In addition, the aperture can be adjusted by changing the UV intensity, or other properties of the glass can be changed by mixing borate or phosphate into the resin.
A major Swiss glassware distributor has expressed interest in using the technology, which is similar to the technology being developed by the Karlsruhe Institute of Technology in Germany.