Molybdenum Disulfide and Nano-Diamonds Produce Onion-Like Dry Lubricant

Recently, the researchers in the Argonne National Laboratory have accidentally discovered that the reaction between molybdenum disulfide and nano-diamonds can produce onion-like dry lubricant which can last long.

In 2015, Anirudha Sumant and his colleagues of Nanoscience and Technology division at the Argonne National Laboratory have demonstrated the super-lubricity (near-zero friction) at the engineering scale for the first time through the combination of graphene and nano-diamond and made the breakthrough of solid lubrication technology. This method is revolutionary, and his team has continued to develop this technology since then.

Recently, Sumant replaced graphene with molybdenum disulfide and observed the performance of other two-dimensional material. He expected that the resultant material to resemble the graphene-nanodiamond lubricant. However, Sumant and Diana Berman did not find any nanodiamonds in this material but surprisingly discovered onion-like carbon spheres. The truth is that the molybdenum disulfide is decomposed into molybdenum and sulfur and reacted with the nanodiamonds. In the end, it is converted into onion-like carbon.

The Argonne National laboratory's research team realized that sulfur diffusion is increasing the strain of nanodiamonds, and then destroys them to convert them into onion-like carbon. Sumant said that this was a blessing in disguise, and their efforts have uncovered another secret about how other two-dimensional materials interact with nanodiamonds.

The friction of this new combination is 10 times lower than of some non-stick coatings including fluoropolymers, which means less heat and less wear on parts and equipment. Although this paper was only recently published in Nature Communications, the Argonne National Laboratory believes that it has the potential to be industrialized. It also can be used to make parts that we can't make today, especially with metal stamping. 

Sumant believes that this new onion-like carbon lubricant has at least three advantages. Firstly, it is much cleaner because no hazardous chemicals are thrown away during the process. Secondly, it can readjust itself continuously and last longer instead of generating catastrophic failure modes like other common lubricants. Thirdly, although molybdenum disulfide is more expensive than graphene, the needed amount is so small that the cost is low.