MXenes gain space in anti-friction technologies
MXenes gain space – Soon after graphene came the MXenes, 2D materials that have already come out ahead of their more famous relative in several areas, mainly in the manufacture of batteries.
While graphene consists of sheets of pure carbon, only one atom thick, MXenes, also known as MAX phases, follow the general formula Mn+1AXn, where M is a transition metal, A is an element of the A group of Periodic Table and X is carbon or nitrogen.
If you take a bunch of graphene sheets and stack them up, you’ll have graphite, the same one that’s used in the tips of pencils, but it’s also an excellent lubricant because the graphene sheets easily slide over each other.
Researchers in Austria have now found that, in addition to their promising technological future, MXenes also slide very well.
In fact, they have proven to be far superior lubricants because they come with a high engineering value addition: They withstand very high temperatures.
“You first start with so-called MAX phases, which are special layer systems consisting of titanium, aluminum and carbon, for example,” explained Professor Carsten Gachot of the University of Technology in Vienna. “The crucial trick is to rip the aluminum out using hydrofluoric acid.”
What’s left then is a pile of atomically thin layers of titanium and carbon that lay loose on top of each other like sheets of paper. Each layer is relatively stable on its own and can be easily shifted against each other.
And, unlike oils, the material is solid and can take on the consistency of grease or a powder, such as graphite.
By testing the lubricating effect of this material, friction between two steel surfaces was reduced to just 16% of abrasion without lubrication.
And what caught the eye was the exceptionally high wear resistance: Even after 100,000 cycles of movement, the MXene lubrication layer continued to run smoothly.
“Similar things have been tried with other thin-film materials like graphene or molybdenum disulfide,” said Gachot. “But they react sensitively to moisture in the atmosphere. Water molecules can change the binding forces between individual layers. With MXenes, on the other hand, this plays a smaller role. a larger scale.”