Of all the materials that can be 3D-printed, glass is still one of the most challenging to work with. Scientists at Switzerland's ETH Zurich research center are working on changing that, though, with a new and reportedly better glass-printing technique.
Although it already is possible to 3D-print glass objects, the most commonly-used processes involve either extruding molten glass, or selectively sintering (laser-heating) ceramic powder to convert it into glass. The former involves high temperatures and thus requires heat-resistant equipment, however, while the latter can't produce particularly complex objects.
The ETH procedure is designed to address both of these shortcomings.
It incorporates a photosensitive resin, which is made up of a liquid plastic along with organic molecules to which silicon-containing molecules are bonded – in other words, they're ceramic molecules.
Utilizing an existing process known as Digital Light Processing, the resin is exposed to a pattern of ultraviolet light. Wherever the light hits the resin, the plastic monomers cross-link to form a solid polymer. That polymer has a labyrinth-like inner structure, with the spaces within the labyrinth being filled by the ceramic molecules.
The resulting three-dimensional object is subsequently fired at a temperature of 600 ºC (1,112 ºF), burning away the polymer to leave only the ceramic behind. In a second firing, this one at about 1,000 ºC (1,832 ºF), that ceramic densifies into a transparent, porous glass. The object does shrink significantly as it's converted into glass, a factor which has to be allowed for in the design process.
Although the objects created so far have been no larger than a die, they are quite complex in shape. Additionally, it's possible to tweak the pore size by varying the intensity of the UV light, plus other characteristics of the glass can be changed by mixing borate or phosphate into the resin.
A major Swiss glassware dealer has already expressed interest in utilizing the technology, which is somewhat similar to a technique being developed at Germany's Karlsruhe Institute of Technology.
Source: ETH Zurich
