Researchers develop cold sintering, predict it could lead to huge productivity and cost gains.
Ceramics is a material whose creation dates back to tens of thousands of years.
“Since the stone age, ceramics have been fabricated by sintering at high temperatures,” said Clive Randall, Director of Materials Research Institute and Professor at Penn State University.
Sintering is the process of firing ceramic at high temperatures—usually above 1,000 degrees Celsius—for hours at a time.
The exposure to high temperatures leads the individual particles to meld, creating a more compact and mechanically strong material.
However, this traditional fire process may now become obsolete due to new developments.
Cold Sintering Process
A team of researchers at Penn State led by Randall developed a new method for sintering that requires much less time and energy than the traditional method.
Randall’s new approach is called cold sintering, and incorporates liquids into the process, which takes place at temperatures ranging from room temperature to 200 degrees Celsius.
“What we’re doing is using a liquid in a dissolution process. It then works by an evaporation process,” added Randall.
Employing an evaporating process has been done before, but what makes the cold sintering process different is that during the evaporation “it’s capturing all the exchange, and diffusional and growth processes that you need to drive the sintering,” explained Randall.
Additionally, cold sintering can work with several types of materials at once whereas traditional sintering cannot.
Ceramics in high demand, such as metals and polymers, all have differing thermal stabilities as well as shrinkage and chemical incompatibilities.
Because of their differing properties, it’s hard to sinter these materials at high temperatures, but “these problems are minimized in cold sintering,” because it functions for a diverse amount of materials, said Randall.
“I see cold sintering process as a continuum of different challenges,” he added. “It really all depends on the systems and chemistries you are talking about.”
How Cold Sintering Benefits Manufacturing
Cold sintering has the potential to increase throughput and manufacturing yields significantly.
Randall and his team recently explained how the cold sintering process could be used to sinter ceramic and thermoplastic polymer materials together.
Three different types of polymer are chosen to work with three types of ceramics to display the diversity of materials applicable to the process.
These materials can then be sintered to high density at 120 degrees Celsius for 15 to 60 minutes.
Additionally, through cold sintering, architectural materials—such as ceramic bricks, biomedical implants, thermal insulation, and many types of electronic components—are now open to exploration.
Sustainability in Manufacturing
With the cold sintering process only taking minutes, the energy and time saved from it could lead to huge productivity and cost gains for manufacturing.
Sustainability is a high priority to Randall who feels that “in this day and age when we have to be incredibly conscious of the carbon dioxide budget, the energy budget, rethinking many of our manufacturing processes, including ceramics, becomes absolutely vital.”