United States. Researchers at Purdue University have developed a new process to help overcome the fragile nature of ceramics and make it more ductile and durable. The Purdue team calls the process "instant sintering," which adds an electric field to the conventional sintering process used to form bulk components from ceramics.
The study shows that the application of an electric field to the formation of ceramics makes the material reform as easily as metal at room temperature. The Purdue team specifically applied their technique to titanium dioxide.
Ceramics are mechanically strong, but tend to fracture suddenly when slightly strained under a load, unless exposed to high temperatures.
"We have been able to show that even at room temperature, ceramics sintered with the electric field surprisingly deform plastically before fracturing when compressed at high stress," said Haiyan Wang, Basil S. Turner professor of engineering in Purdue's College of Engineering.
"Nanotwins have been introduced into various metal materials to improve strength and ductility. However, there are few previous studies showing that nanotwins and stacking failures can significantly improve ceramic plasticity," said Jin Li, a researcher and postdoctoral PhD in the research team.
The significantly improved ductility at room temperature in titanium dioxide is attributed to unusually high-density defects, such as stacking failures, twins, and dislocations, formed through the process of instantaneous sintering.
"The existence of these defects eliminates the need for defective nucleation in ceramics, which usually requires a large nucleation effort, greater than the fracture stress of ceramics," Wang said.
Li, the first author of the Purdue paper, said: "Our results are important because they open the door to using many different ceramics in new ways that can provide more flexibility and durability to withstand heavy loads and high temperatures without catastrophic fragile failure."
Improved plasticity for ceramics means greater mechanical durability during operation at relatively low temperatures. The sample could also withstand almost as much compression stress as some metals before cracks begin to appear.
"These ductile ceramics find many technologically important applications," said Xinghang Zhang, a professor of materials engineering and co-principal investigator of the research team. "It can be applied to defense operations, automobile manufacturing, nuclear reactor components and sustainable energy devices."
Data Source Provider: Purdue University.
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