Researchers at an Austrian university have found lubricating properties in a two-dimensional nanomaterial, mXene, they announced last week. The material, pronounced “maxene,” can be used as a lubricant even under extreme temperature conditions.
The group from the Vienna University of Technology, or TU Wien, worked alongside teams from Saarland University in Germany, Purdue University in the United States and the Universidad de Chile in Chile.
“Just like the carbon material graphene, mXenes belong to the class of so-called 2D materials: their properties are essentially determined by the fact that they are ultra-thin layers, single atomic layers, without strong bonds to the layer above or below,” TU Wien explained in a press release issued April 20.
Because these layers can easily be shifted against each other, it makes the material good for lubrication. “Without generating abrasion, extremely low-resistance sliding is made possible,” the press release said. “The friction between steel surfaces could thus be reduced to one-sixth – and with exceptionally high wear resistance. Even after 100,000 movement cycles, the mXene lubricating layer still functions without problems.”
This makes the powdery lubricant useful under extreme conditions, like space. According to the university, lubricating oil would evaporate in a vacuum during space missions while mXene in the form of fine powder could be used in the same application.
“Similar things have been tried with other thin-film materials, such as graphene or molybdenum disulphide,” Carsten Gachot, professor and head of the tribology group at the Institute of Engineering Design and Product Development at TU Wien added. “But they react sensitively to moisture in the atmosphere. Water molecules can change the bonding forces between the individual layers. With mXenes, on the other hand, this plays a lesser role.”
MXenes also offer heat resistance properties, and can be used in the steel industry where mechanically moving parts can sometimes reach a temperature of several hundred degrees Celsius, Gachot said. Many other lubricants oxidize at high heat and lose their lubricity.
“There is also already great interest in these materials on the part of industry,” Gachot said. “We assume that such mXenes can soon be produced on a larger scale.”
The nanomaterial have at least one dimension between 1 and 100 nanometers. A nanometer is approximately one billionth of a meter. Due to some of their unique properties, researchers have looked for ways to use nanomaterials in a variety of industries and applications, including semiconductors, surface engineering and medicine.