Objects such as wine glasses, missile heads, thermal barrier coatings on engine blades, automotive parts, electronic and optical components are usually made of ceramics. Although the mechanical strength of the ceramic is very high, if it is not exposed to high temperature, it will suddenly break when pulled slightly under load.
However, researchers at Purdue University have developed a new process that allows ceramics to overcome the fragile characteristics and make them more resilient and durable. Purdue University calls this process "flash sintering", which adds an electric field to the traditional sintering process to make ceramic parts in large quantities.
Professor Haiyan Wang of the School of Engineering at Purdue University said: "We have been able to prove that even at room temperature, ceramics sintered by electric field will undergo plastic deformation (elasticity) under high strain compression, which is very surprising."
The study showed that applying an electric field during the formation of ceramics can make the material deform at room temperature almost like a metal. The Purdue University research team specifically applied its technology to titanium dioxide, a widely used white pigment.
Jin Li, a postdoctoral fellow and researcher in the research team, said: "Previously, nano twins were introduced into various metal materials to improve their strength and ductility. However, there has been little research before that shows that nano twins and stacking faults can be greatly improved The plasticity of ceramics. "
The ductility of titanium dioxide at room temperature is significantly improved due to the occurrence of high-density defects such as stacking faults, twins, and dislocations during the flash firing process. The existence of such defects eliminates the need for nucleation of ceramic defects, and nucleation of defects usually requires a larger nucleation stress than the fracture stress of the ceramic.
The first author of this paper, Li, said: "Our research results are very important. It opens a door for the use of many different ceramics in new ways. Such new methods can give ceramics greater flexibility and durability. Can withstand heavy loads and high temperatures without being fragile. "
The increased plasticity of the ceramic means that its mechanical durability will be higher at relatively low temperatures. Prior to the occurrence of cracks, the researchers ’sample ceramics were able to withstand as much compressive stress as some metals.
Xinghang Zhang, a professor in the Department of Materials Engineering and co-head of the research group, said: "This type of ductile ceramics can be used in many important applications, such as defense fortifications, automobile manufacturing, nuclear reactors, and sustainable energy equipment."