The new method applies to a broader range of ceramics and is scalable.
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A team of researchers at Purdue University’s College of Engineering has revealed a novel method that could expand the use of ceramics in industrial applications.
Although lauded for their hardness, durability, and heat resistance, ceramics have long been plagued by a major drawback- brittleness. Hindered by an inherent lack of plasticity— the ability to deform without shattering— they have found limited industrial applications.
However, a team of researchers at Purdue University’s College of Engineering has made a breakthrough that could expand the horizons for these versatile materials.
Professors Haiyan Wang and Xinghang Zhang led the team that developed and validated the patent-pending technique for enhancing the plastic deformability of ceramics at room temperature.
“Such a strategy can prominently improve the room-temperature plastic deformability of ceramics and holds the promise to inject ductility, or the ability to be drawn into near net shape, into ceramics in the near future,” explained Zhang, a professor of materials engineering at Purdue’s School of Materials Engineering.
Ceramics bend at high temperatures when dislocation activity is possible. These dislocations are defects that allow atomic rearrangement and enable deformation. A dislocation can glide within crystals, enabling plastic deformability at certain stress levels. At room temperature, these dislocations are scarce, making ceramics brittle.
“In ceramic materials, it is difficult to nucleate dislocations at room temperature, as the fracture stress in ceramics is much less than the stress to nucleate dislocations at such temperatures,” explained Wang, Basil S. Turner Professor of Engineering, in a statement.
In contrast, metals have an abundance of mobile dislocations, even at ambient temperatures, which makes them ductile. “The way to improve plasticity for ceramics is to nucleate abundant dislocations in ceramics before we start to deform them,” Zhang added.
Previous research efforts attempting to enhance ceramics’ deformability found limited success. The Purdue team’s approach complements these attempts. Their novel approach involves introducing dislocations into ceramic materials by preloading them during deformation at high temperatures.
“After the preloading treatment, single-crystal titanium dioxide exhibited a substantial increase in deformability, achieving 10% strain at room temperature,” Zhang reported. “Aluminum oxide also showed plastic deformability, 6% to 7.5% strain, using the preloading technique.”
Chao Shen, a graduate student on the team, explained that the dislocations improve their plasticity at room temperature once the specimens are cooled. Compared to previous research which attempted to improve ceramic ductility via flash sintering, the new method applies to a broader range of ceramics.
“Preloading dislocations may also be much easier to scale up in practice for large-scale processing and treatment of ceramics than flash sintering,” Wang added.
Ceramics are integral to industries ranging from aerospace and transportation to power plants and manufacturing. Their mechanical strength, chemical inertness, wear and corrosion resistance, and insulating properties make them indispensable for numerous applications. These include bearings, capacitors, electrodes, and thermal barrier coatings.
The Purdue research team plans to collaborate with industry partners to demonstrate large-scale implementations of their approach across various ceramic systems. They disclosed their innovation— supported by the U.S. Office of Naval Research— to the Purdue Innovates Office of Technology Commercialization which has applied for a patent to protect intellectual property.
barrel pump Details of the team’s research were published in the peer-reviewed journal Science Advances.