Ceramics are easily broken when pressed, but now, scientists in the United States and Singapore have created a very tiny ceramic that will not only break after being broken, but also has shape memory, which can be widely used in biomedical and fuel cell fields. The study was published in the latest issue of the journal Science.
The research leader, MIT Professor of Materials Science and Engineering, Christopher Shu explained that having shape memory means that when this material is bent and then heated, they will return to their original shape. In the 1950s, scientists for the first time knew this kind of material with shape memory. Shu said: "People always think that metal and some polymers have this property, and never thought about ceramics."
In principle, the molecular structure of ceramics can make them have shape memory, but ceramic is fragile and fragile is a barrier. Recent research shows that the key to making ceramics flexible and shape-memory is to make them small.
The researchers did this in two key ways. First, they created small ceramics that were invisible to the naked eye. Then, they allowed a single grain to cross the entire structure and removed the grain boundaries because fragmentation was more likely to occur at these boundaries. In the end, they made tiny ceramic samples, and 7% of the entire sample could be bent and deformed. Alan Lai, a graduate student, said: “Only 1% of most items, including ordinary ceramics, can be bent. And we obtained in the latest study that these long fibers with a diameter of only 1 micron can be bent between 7% and 8%. Not broken."
The latest material combines the advantages of metal and ceramics. The strength of the metal is lower, but it is very easy to deform; while the strength of the ceramic is greater, but it is almost impossible to bend, the newly developed ceramics are both "similar to the strength of the ceramic and the softness of the metal."
Shu said that the new ceramic is expected to be used to make micro and nano devices; it can also be used as a micro-excited device widely used in the biomedical field to trigger tiny implants to release drugs.
Lai said that the ceramic materials used in the latest research are made of zirconia, but the same technology should also be applied to other ceramic materials. Zirconia is "the most studied ceramic material" and it is also widely used in engineering. Zirconia is also used in the field of fuel cells. Although the fuel cell does not require flexibility, having flexibility increases its resistance to damage.
