Revolutionary technique produces injection-molded glass objects
Plastic is a lot easier to work with than glass, which is one of the reasons it's used so much more often. That may be about to change, though, thanks to a new process that allows glass to be injection-molded – just like plastic.
The technology was developed by a team at Germany's University of Freiburg, led by Drs. Bastian E. Rapp and Frederick Kotz. It's being commercialized under the name of Glassomer.
The process begins with small polymer granules, each one of which has tiny silica glass particles dispersed within it. These granules are poured into a standard injection molding machine that melts them, and then injects the molten polymer into a mold. Once the polymer has cooled and hardened, the item is ejected out of the mold. At this point, it still looks like it's made of regular plastic.
After being washed in water and placed in a 600 ºC (1,112 ºF) oven, however, all of the polymer is washed out or burned away – this leaves only the linked glass particles behind. When the item is then heated to 1,300 ºC (2,372 ºF), those particles fuse together via a process known as sintering, forming a pure quartz glass finished product.
"The particles basically smoothly flow into each other," Kotz tells us. "The component however stays in shape and just shrinks by a factor of around 15 percent in each direction."
Not only does the technology potentially allow for complex, detailed items to be quickly made out of glass in large quantities, but it also doesn't require the 2,000 ºC (3,632 ºF) temperature that's required to melt regular glass – this means it's considerably more energy efficient than conventional glass-good manufacturing methods. And as an added bonus, the polymer binder that is washed out of the items can be reused.
"For decades, glass has often been the second choice when it comes to materials in manufacturing processes because its formation is too complicated, energy-intensive and unsuitable for producing high-resolution structures," says Rapp. "Polymers, on the other hand, allow all of this, but their physical, optical, chemical and thermal properties are inferior to glass. As a result, we have combined polymer and glass processing. Our process will allow us to quickly and cost-effectively replace both mass-produced products and complex polymer structures and components with glass."
The new technique is described in a paper that was recently published in the journal Science.