A ceramic sample created using pressure rather than heat. (Image courtesy of ETH Zurich.)

Researchers have developed a new process for making ceramics that replaces firing with compression. They call it cold sintering.

For nearly 30,000 years, humans have been working with ceramics, shaping and forming materials and then firing them to set their final form. While the firing process has been instrumental in transforming soft, weak or impure materials into high performance final products, it requires a significant energy investment.

How much?

Well, many ceramic materials have to be fired at temperatures in excess of 1,000°C, and that requires an enormous amount of energy and control.

However, researchers at ETH Zurich have looked back to an even more ancient source, namely the geological processes that form rock, as an inspiration for their new ceramic manufacturing technique.

Starting with a calcium carbonite nanopowder and a bit of water, the researchers were able to use a hydraulic press to compress their slurry into a ceramic solid without having to apply heat.

“The manufacturing process is based on the geological process of rock formation,” explained Florian Bouville, a postdoc in the Complex Materials Group. “Our work is the first evidence that a piece of ceramic material can be manufactured at room temperature in a short amount of time and with relatively low pressures,” said ETH professor André Studart.

Although Bouville and his team have only been able to create samples that are an inch in diameter, the material has shown that it can withstand ten times the force required to break concrete and it can be produced in an energy efficient manner.

In the coming years, material researchers will face challenges in scaling up the cold sintering method for ceramic forming as larger volumes workpieces require greater force and sustained pressure.

For more ceramics news, find out how these 3D-printed ceramics withstand ultrahigh temperatures.