The Massachusetts Institute of Technology (MIT) recently announced that researchers at the University of Lyon, France, who are visiting the university, have discovered that nanotubes made of different materials have unexpected performance differences, some of which are smooth, and some are very Sticky.
The shape of the nanotube is a tiny cylinder like a straw, and its diameter is only one-thousandth of the diameter of the hair. It can be used in solar cells, chemical sensors and reinforced composite materials. At present, the key research object of nanotubes is carbon nanotubes with conductive or semi-conductive properties, but the nanotubes of other materials are similar in structure and performance.
When comparing the functional characteristics of carbon nanotubes (CNTs) and boron nitride nanotubes (BNNMTs) with very similar structures, the researchers found that at least one key characteristic (that is, friction), these two nanotubes are not only different, but even completely On the contrary, the carbon nanotube wall is extremely smooth and has almost no friction, which can be called super-lubricating; while boron nitride nanotubes show very high friction.
The specific method of the experiment is to suspend the nanotube with two fulcrums, and then pull it to both sides with a precisely calibrated force. In fact, like the old telescope, the nanotube is composed of tubes that are nested together one by one. When pulled by an external force, it also extends one by one like a telescope until it is finally broken. The researchers recorded the amount of tension each time a tube was pulled out. Through the recorded tensile data, they found that the strength used to stretch carbon nanotubes and boron nitride nanotubes was completely different.
The researchers believe that this discovery opens up future research on nano-friction theory and is conducive to promoting the development of nano-electromechanical systems and equipment.
The calculation formula of friction force has been learned by junior high school students-the friction coefficient is multiplied by the contact force. In fact, this is just a practical simplified form of classical mechanics. Until now, people can only list the friction coefficients of various materials empirically, without understanding why. Therefore, the more microscopic the scientist is, the less predictable the friction. Nanodevices appear to be miniature versions of macroscopic devices, but the friction is not reduced proportionally. Why are carbon nanotubes smoother than boron nitride nanotubes? This simple question is intriguing. Subsequent research may lead to new insights and applications. Seeing the Weizhi book, it's endless fun.
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