Items such as drinking mugs, missile heads, thermal barrier coatings on engine blades, auto parts, electronic and optic components are commonly made with ceramics. The ceramics are mechanically strong, but tend to fracture suddenly when just slightly strained under a load unless exposed to high temperatures.

Now, a team led by Purdue University researchers has developed a new process to help overcome the brittle nature of ceramics, making them more ductile and durable. The Purdue team calls the process “flash sintering,” which adds an electric field to the conventional sintering process used to form bulk components from ceramics.

Credit: Purdue University/Chris Adam

We have been able to show that even at room temperatures, ceramics sintered with the electric field surprisingly deform plastically before fracture when compressed at high strain.

—Haiyan Wang, the Basil S. Turner Professor of Engineering in Purdue’s College of Engineering

An open-access study published in Science Advances demonstrates that applying an electric field to the formation of ceramics makes the material almost as easily reshaped as metal at room temperature. The Purdue team specifically applied its technique to titanium dioxide, a widely used white pigment.

Nanotwins have been introduced in various metallic materials to improve strength and ductility. However, there are little prior studies that show nanotwins and stacking faults can significantly improve the plasticity of ceramics.

—Jin Li, first author

The significantly enhanced room temperature ductility in titanium dioxide is attributed to the unusually high-density defects, such as stacking faults, twins and dislocations, formed through the flash sintering process.

The existence of these defects remove the need for defect nucleation in ceramics, which typically requires a large nucleation stress, greater than the fracture stress of ceramics.

—Haiyan Wang

Improved plasticity for ceramics means more mechanical durability during operation at relatively low temperatures. The sample also could withstand almost as much compression strain as some metals do before cracks started to appear.

These ductile ceramics find many technologically important applications. It can be applied to defense operations, automobile manufacturing, nuclear reactor components and sustainable energy devices.

—Xinghang Zhang, professor of materials engineering and co-principle investigator

This Purdue-led research is supported by the Office of Naval Research in collaboration with the University of California, Davis, Rutgers University and Naval Research Laboratory.

The research team is working with the Purdue Research Foundation Office of Technology Commercialization to patent their work. They are looking for partners for continued research.

Resources

• Jin Li, Jaehun Cho, Jie Ding, Harry Charalambous, Sichuang Xue, Han Wang, Xin Li Phuah, Jie Jian, Xuejing Wang, Colin Ophus, Thomas Tsakalakos, R. Edwin García, Amiya K. Mukherjee, Noam Bernstein, C. Stephen Hellberg, Haiyan Wang, Xinghang Zhang (2019) “Nanoscale stacking fault–assisted room temperature plasticity in flash-sintered TiO₂” Science Advances Vol. 5, no. 9, eaaw5519 doi: 10.1126/sciadv.aaw5519