Researchers from ETH Zurich in Switzerland developed the method, which is based on stereolithography and uses a special resin containing plastic and organic molecules.
Printing glass is “not easy”, the researchers said. Some previous approaches have printed molten glass, which requires extremely high temperatures and heat-resistant equipment. Others used powdered ceramic particles printed at room temperature and then sintered to create glass, but the ETH Zurich team said objects made this way are not very complex.
The new process uses commercially-available digital light processing technology. UV light patterns irradiate the resin, which hardens where it strikes. The plastic monomers combine to form a labyrinth-like structure, while ceramic-bearing molecules fill the interstices, or spaces in between.
Objects are built up layer-by-layer. The team can change various parameters in each layer, including pore size after an accidental discovery – weak light results in large pores, while intense illumination produces small pores.
The microstructure of the objects is also modified by mixing silica with borate or phosphate and adding it to the resin. Different types of glass can even be combined in the same object.
After printing, the objects are fired at 600ºC to burn off the polymer framework and then at about 1,000ºC to densify the remaining ceramic structure into glass. During firing the objects shrink significantly, but they also become transparent and hard like window glass.
The process is not yet suited to large objects like bottles, drinking glasses or window panes, but researcher Kunal Masania said that was not the aim. Although the final objects are no bigger than dice, the aim was to prove the feasibility of producing glass objects of complex geometry using a 3D printing process.
The team has applied for a patent and is negotiating with a Swiss glassware dealer who wants to use the technology. It could have other applications in future.
The research was published in Nature Materials.
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