American engineers have invented flexible ceramics

Engineers bent with ceramics

Grigory Kolpakov, <url>Ceramics are not necessarily something fragile and breakable.

This was proved by American engineers who developed a ceramic material capable of bending and memorizing the shape.

Researchers from the Massachusetts Institute of Technology (MIT), together with colleagues from Singapore, managed to create ceramics that bends and does not break, and even at the same time remembers the shape. They published an article about this amazing material in the journal Science: Lai et al., Shape Memory and Superelastic Ceramics at Small Scales.

A miracle, however, did not happen, and if someone dreams of ceramic suspenders or gasoline hoses, then these dreams are not destined to come true yet. Scientists managed to create superelastic ceramics only at the level of microscopic hairs, indistinguishable to the human eye. And most importantly, if such ceramics are bent, then when heated, it will return to its original shape.

"The ability of materials to remember the shape has been known since the fifties of the last century," says one of the participants in this development, MIT metallurgy professor Christopher Shu. – However, so far it has been found only in metals and some polymers, but not in ceramics. In principle, the molecular structure allows ceramics to have shape memory, but the main obstacle here was its fragility and predisposition to cracking."

So that the sample has a shape memory and does not crack, there is only one way so far – to make it very small: the smaller the object, the higher its resistance to cracking. And since cracks usually appear at the boundaries of ceramic grains, the researchers have ensured that the hair is a single grain.

Most ceramics can only be bent by one percent, and after several bends, the material will still begin to crack. The resulting ceramic microstrips bend by seven to eight percent any number of times.

Diagram and micrograph from an article in Science – VMThe thickness of such a hair is one micron.

For nanotechnology, this is not so little. According to the researchers, such materials will be able to find many applications in this area.

For example, they can be very useful for biomedical nano- and micro devices. In particular, ceramics with shape memory can be indispensable for the manufacture of micro-drives. Compared to micro-drives made of other materials, such ceramic hairs will regain their original shape, that is, straighten out, with record strength.

Anyway, it was possible to create a material that combines the best qualities of metals and ceramics, while getting rid of the insufficient hardness of metals and the fragility of ordinary ceramics. He, according to Shu, has "the strength of ceramics and the plasticity of metal."

When creating superelastic ceramics, scientists used zirconium dioxide, which is very well studied and widely used in industry, in particular in fuel cells, although the reader may be familiar with it only from dental cermets. And although flexibility and shape memory are not required in all these applications, the elasticity of the new material, according to its authors, can make it more resistant to damage. At the same time, it is possible to make elastic not only zirconium ceramics – the same technology can be applied to other types of ceramic materials.

Portal "Eternal youth" http://vechnayamolodost.ru30.09.2013