“Broken nanodiamonds are forever,” or so says a team of scientists at the US Department of Energy’s (DOE) Argonne National Laboratory. By combining broken nanodiamonds with two-dimensional molybdenum disulfide layers, they’ve managed to produce a self-generating, very-low-friction dry lubricant with hundreds of applications that lasts practically forever.
Dry lubricants are an important tool for modern engineers, with a number of advantages over their liquid counterparts. Unlike greases and oils, dry lubricants aren’t as chemically active, don’t leak or squeeze out, and don’t capture dust or grit. In addition, they don’t break down at high temperatures and some work in the vacuum of space where liquids would evaporate or freeze solid.
One of the most common solid lubricants is graphite powder or paste, which is made up of plate-like carbon molecules with water molecules between them that act like extremely tiny ball bearings. It’s used for lubricating locks, door knobs, and bicycle chains, as well as high temperature or high pressure environments. However, there are more exotic dry lubricants.
About three years ago, a team led by Anirudha Sumant of the Nanoscience and Technology division of Argonne found that by mixing graphene with nanodiamonds, it was possible for the first time on an engineering scale to produce superlubricity or near-zero friction. Now Sumant’s team has taken this a step further by replacing the graphene with molybdenum disulfide – another common dry lubricant that’s widely used in space industries because it performs well in a vacuum.