QuasiCrystals, Shechtmanite… Future Applications.
06.10.2011
Surface CoatingsAn important area of application is the use of quasicrystals as materials for surface coatings, which benefit from the hardness of quasicrystals. The most prominent example is the use of quasicrystalline coatings in frying pans – an application famous in the quasicrystal community as it has served as a key example. Recently, quasicrystal-coated frying pans appeared on the market, and are sold by the French company Sitram under the trademark
Cybernox.
Due to their particular physical and chemical properties, quasicrystalline coatings are suited for this kind of application. They are also rather cheap which makes them even more interesting for industrial applications.
Alloys Containing Quasicrystalline Nanoparticles
A different way to circumvent the brittleness of quasicrystalline bulk material while preserving some of its useful properties is the use of an Al-based alloy reinforced by precipitation of icosahedral particles in the nanometer range. Such materials, which are now commercially available in Japan, are of great technological interest as they can be strong but much lighter than other materials with comparable physical properties.
Examples of existing applications include razor blades and surgeon’s instruments, though this may have been more by chance than being an intentional application of quasicrystals. Experts predict that a similar use could soon find its way to the aviation industry.
Hydrogen Storage
A third, and maybe more speculative, application concerns the use of quasicrystals as a reversible storage medium for hydrogen. The most promising quasicrystal materials for hydrogen storage are Zr-based quasicrystals. For such systems, storage capabilities of almost two hydrogen atoms per metal atom have been reported, comparable to the storage capability of the Ti-Fe hybrides which have already been applied in non-polluting internal combustion engines. Further investigation are being carried out to reach the stage of industrial applicability.
See also: Quasicrystals and the Speed of Light.
Prof. Dan Shechtman Discusses Quasicrystal Applications
(Oct. 2011)
“There is always something new in quasicrystals. There are so many people working on it around the world, so every month there are new developments. If you use a material for an application, then you need a special property that will be better than other materials—otherwise, why use this material? Quasi-periodic materials have certain properties which are unique, such as electrical properties, optical properties, hardness and nonstick properties. The direction of light through this material is different. Electrically, they behave in a very peculiar way depending on temperature. Some of these properties have been put to use.
The first application was nonstick coating on frying pans and cooking utensils. If you cook on quasicrystals, your omelet will not stick to it, like Teflon. But unlike Teflon, if you use a knife in the [quasicrystal] skillet, you will ruin the knife. When you have Teflon and you use a knife, you ruin the Teflon. Ruined Teflon is not healthy. I have a frying pan which is plasma-coated with quasicrystals and it works fine. It was made by a French company, Sitram. They closed the production line because they had a few problems in the reaction of the coating with salt. If people cook with a lot of salt it will etch the quasicrystalline coating. People didn’t like it, so they did not continue.
Sandvik, a company in Sweden, produces a precipitation-hardened stainless steel that has interesting properties. The steel is strengthened by small quasicrystalline particles and it does not corrode. It is an extremely strong steel. It is used for anything that touches the skin, for instance, razor blades or surgery tools. When a material deforms in such a way that it will not spring back, in most cases, the deformation is due to a process called dislocation glide. There are defects in the material that cause dislocations. If they are free to move, then it is easy to bend the material. But if something stops them, then it is more difficult and the material is harder and stronger. These little quasicrystalline particles impede the motion of dislocation in the material.
Because some of these materials have a low coefficient of friction, and they have nonstick properties and are also hard, imagine what would happen if you produce quasicrystalline powder in tiny little balls by rapid solidification process, a gas-atomizing process, then you can embed the fine powders in plastic. Because these particles are strong and can withstand friction and wear, you can make gears from this plastic and the gears will not erode because of these embedded particles. It’s like a protection from erosion. This can serve in ventilators and fans that have plastic gears. Also, the heat conductivity of some of these quasicrystals is very poor. It’s almost an insulator. So you can coat with it and it will insulate against heat transfer.
This is an important discovery, because it’s the first one found in nature, but there are no practical applications. There are many, many metals, but if you think that all the metals can be used for something useful, think again. Look at construction materials. We have steel, which is based on iron, we have aluminum alloys, magnesium alloys, titanium-based alloys, nickel-based alloys, copper alloys, and that’s about all, if I haven’t forgotten any. What do all the other metals do? What are the applications of ytterbium? What are the applications of all the other metals? So to have an application for a material is not trivial.”
