Earlier this month, tribologists and physicists at the U.S. Department of Energy (DOE) Argonne National Laboratory published news of their (self-described) “self-healing diamond-like carbon coating [that] could revolutionize lubrication” in the journal Nature. The researchers claim to have discovered a unique and revolutionary ultra-durable carbon-based tribofilm, formed in-situ within an operating automotive engine by use of its own normally-generated heat and pressure. One of the primary stated objectives of this novel approach to lubrication science was the reduction – or possible outright elimination – of common (environmentally-unfriendly) AW and EP additives in modern motor oils.
“This is a very unique discovery, and one that was a little unexpected,” said Argonne Distinguished Fellow Ali Erdemir, who lead the research team. As stated in the ANL press release, this new concept of in-situ synthesis of carbon-based tribofilms “could have profound implications for the efficacy and durability of future engines and other moving metal parts….”
Rather than using specialized sacrificial hydrocarbon additives to undergo in-operando pyrolysis to form the necessary carbon radicals to synthesize an ultra-durable carbonaceous/graphitic tribofilm, the ANL researchers instead chose to catalytically dehydrogenate molecules of the motor oil itself (via a process of dissociative extraction), utilizing engine part coatings of copper or nickel-containing nitrides of molybdenum or vanadium. In avoiding the use of already published suitable sacrificial additives, the researchers merely had to deposit and adhere the aforementioned metal-nitride nanocrystalline catalytic coatings to the subject engine parts. These coatings then served to regenerate the tribofilm as it became worn from the surface of the coated parts during normal use.
Ball-on-disk tests, at pressures exceeding 1 gigapascal, revealed that the “novel” as-synthesized tribofilm substantially reduced friction and virtually eliminated detectable wear.
The necessary molecular dynamics insights for this discovery were provided by Argonne’s Leadership Computer Facility (ALCF) and its $200 Million (10-petaflop) IBM Blue Gene/Q Supercomputer known as MIRA, along with computers from the National Energy Research Scientific Computing Center (NERSC) at Lawrence Berkley National Lab. As these impressive computing resources are all DOE Office of Science User Facilities, it is comforting to know that the research done was in keeping with Argonne’s charter to “work closely with researchers from … companies, universities and [government] agencies to … advance America’s scientific leadership and prepare the nation for a better future;” this mission, accomplished through efforts such as the collaborative CERC/Argonne TRUCK program, aimed at combating global climate change through greater fuel efficiency innovations applicable to medium and heavy-duty trucking both here and abroad.
Further insight into the methods employed and details of the novel in-situ synthesized carbon-based tribofilm can be had from review of the original Nature paper: Carbon-based tribofilms from lubricating oils.
Credit for images: The images used herein are in the public domain or otherwise used under applicable fair use policies.
The Author declares a competing personal/employment financial interest in Phantaslube LLC and its patented Phantaslube® (in-situ) molecular nanopolishing lubrication technology, as the inventor of such technology, and the CEO of Phantaslube LLC and its parent company, Peerless Worldwide, LLC, the assignee of the relevant Patents thereto.