It is a well-known scientific fact: any material expands when heated. However, a team of American scientists went, as they say, against the laws of physics, having obtained a metamaterial by 3D printing, which shrinks when heated.
The work on its creation was carried out as part of the DARPA program for the study of materials with controlled microstructural architecture. The result was a lightweight metamaterial with a negative coefficient of thermal expansion.
Scientists from Livermore National Laboratory, the University of Southern California and the Massachusetts Institute of Technology took part in the research. In the process of 3D printing, they used the so-called projection microstereolithography, with the help of which a complex 3D bi-material was formed, consisting of two substances with a cellular structure.
In it, microscopic rays are combined with voids. The geometry is constructed in such a way that when heated, one material expands more than the second, as a result, the entire structure contracts in three dimensions. As scientists assure, the structure of cells can change in the range from tens to hundreds of degrees, as a result of which their geometry and spatial structure will be rigidly fixed and will neither expand nor contract.
The range of application of the new material includes the creation of passive fasteners of parts in microcircuits, optical fasteners of high accuracy, as well as in special gaskets in places of possible expansion of bridge structures.