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Karlsruhe Inst of Technology achieves 3D printing of glass

25 Apr 2017

New procedure allows complex forms of glass to be made with micrometer features by 3D-printing.

An interdisciplinary team at Karlsruhe Institute of Technology (KIT), Germany, led by mechanical engineer Dr. Bastian Rapp has developed a process using optical-quality glass for additive manufacturing techniques.

The KIT team says that 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 “many new applications in production and research”, such as optics, data transmission, and biotechnology. The work has just been published in Nature and will be presented to the industry for the first time at this week’s Hanover Fair.

How it works

In the KIT approach, the scientists first 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 stereolithography.

Then 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 heating.

Dr Rapp explained, “The shape initially resembles that of a pound cake or sponge cake; it is still unstable, and therefore the glass is sintered in a final step; it is heated so that the glass particles become fused.” Dr Rapp conducts research at the KIT Institute of Microstructure Technology and heads a working group of chemists, electrical engineers, and biologists.

He says that the range of 3D-printing techniques developed so far have been used on polymers or metals, but not on glass with successful outcomes for optical applications.

“Conventionally, where glass was processed into structures, for instance by melting and application by means of a nozzle, the surface turned out to be very rough, the material was porous and contained voids. Here, we present a new method, which is an innovation in materials processing, in which the material of the piece manufactured is high-purity quartz glass with the respective chemical and physical properties,” said Rapp.

Micrometer features

The glass structures made so far by the KIT scientists exhibit feature resolutions in the range of a few micrometers. However, the structures may have total dimensions in the range of a few centimeters.

3D-formed glass structures could find applications in data technology. “The next plus one generation of optical computers will require complicated processor structures,” said Dr Rapp. “3D-technology could be used, for instance, to make small, complex structures from a large number of tiny optical components of different orientations.”

Furthermore, for biological and medical technologies, very small analytical systems could be made from miniaturized glass tubes. In addition, 3D-shaped microstructures of glass could be employed in a variety of optical areas, from eyeglasses meeting special requirements to lenses in laptop cameras.

The development by scientists under Dr Rapp is a result of the NanoMatFutur junior scientist funding scheme run by the German Federal Ministry for Education and Research (BMBF) to support the development of innovative materials for industry and society.

The work performed by the research group headed by Rapp has been funded by the BMBF since 2014 for a total of four years to the tune of approx. €2.8 million. “Our research benefits very much from the interdisciplinary cooperation of various KIT institutes. Besides the Institute of Microstructure Technology, colleagues of the Institute of Nuclear Waste Management and the Institute of Applied Materials, among others, are involved in the project,” said Rapp.

The new glass technology is one of the subjects on show at the KIT booth at the Hanover Fair between April 24 and 28, 2017 (Hall 2, B16 – in the Research and Technology section).

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