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The word "thermal expansion and contraction" may be rewritten. The Lawrence Livermore National Laboratories (LLNL) announced on the 25th that the laboratory engineers cooperated with scientists from MIT, the University of Southern California and the University of California, Los Angeles. Super material. The new structure can also recover the previous volume after cooling, and can be used repeatedly. It is suitable for the production of precise operating parts such as microchips and high-precision optical instruments required in a temperature-changing environment.
The thermodynamic properties of traditional large-volume materials are characterized by thermal expansion and contraction under cold conditions. The metamaterial obtained this time is completely the opposite and it shrinks when it is heated. The material is a micro-lattice structure printed with polyester and another copper-doped polyester, including two parts of the beam and the hollow lattice, because the relative displacement of different materials when heated, making the connection point inward pull Stretching, pulling the entire lattice structure inward, thus exhibiting unique heat shrink properties.
The research team led by MIT mechanical professor Fang Hao Lai undertook the work of the 3D printing part of the study. Fang Haolai said in an e-mail interview with a reporter from Science and Technology Daily that they are using stereolithography 3D printing technology, similar to the combination of inkjet printers and digital exposure machines. First, the droplets of different materials are sprayed on a transparent window, and then the patterns are respectively projected on the back of the droplets to be cured by the digital projector. The illuminated area forms a solid sheet-like structure that attaches to a sample holder and the unexposed droplets on the window are removed. Repeatedly, the desired composite material can be obtained.
According to Fang Haolai, from the perspective of each unit, the new structure is similar to the design of a cable-stayed bridge. Only the relatively flexible resin is replaced by a relatively flexible resin, and the rigid beam becomes a copper-doped resin. When heated, the soft resin first stretches until the stiffened crossbeam is also pulled to rotate relative to the anchoring position. In general, the entire hollow lattice structure is shrinking.
The new structure is suitable for the production of precision parts in a large temperature change environment, such as thermal lens expansion to avoid the focal length drift of the optical lens; prolonged use of heat but does not affect the stability of the micro-chip; improve the efficiency of solar energy devices; In the case of high-temperature foods, dental fillings that perfectly match real teeth; even artificial satellites that pass through the sun's intense heat. (Reporter Nie Cuirong)
Inconel, when heated, forms a thick yet stable oxide layer that protects its outer surface from further attack. This makes it the ideal choice for extreme temperature and pressure applications, where steel and aluminum would succumb to thermal creep. Available in numerous grades, the Inconel alloys exhibit shifting characteristics with slight variations in their chemistry.
In its more basic form, typical applications would include the food industry and heat treatment components. When alloyed with other elements, however, further strengthening and stiffening permits its use in the more demanding areas of the marine, aerospace and chemical processing industries. Alloyed to its peak performance, Inconel then becomes the material of choice in the most critical environments of turbine blades, rocket engines and key nuclear industry components.
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