The study of superlubricity shows that a frictionless state can be achieved on a macro scale

The President of SUNY Polytechnic Institute (SUNY Poly), Dr. Winston “Wole” Soboyejo and postdoctoral researcher Dr. Tabiri Kwayie Asumadu have published a paper titled, “Robust Macroscale Superlubricity on Carbon-Coated Metal Surfaces”. This paper explores an innovative approach to reducing friction on metallic surfaces—an important advance that could have major real-world impacts.

The research is published in the journal Applied Materials Today.

The study shows that superlubricity – a virtually frictionless state once believed to be achievable only at the nanoscale – can now be maintained at the macroscale for long periods of time, under regular atmospheric conditions, through the use of carbon coatings produced in sustainably made from biological waste.

These findings are important for a number of practical reasons. In the automotive industry, more than 30% of the fuel in passenger vehicles is used to overcome friction, so these new coatings can help drastically improve fuel efficiency. In manufacturing and industrial machinery, they can help reduce wear and tear, leading to massive cost savings and reducing the 1–4% of countries’ GDP spent on friction-related equipment issues. In electronics, friction on a minute scale can present large-scale challenges that coatings can help alleviate.

“This research can really affect most industries,” said Dr. Asumadu. “From the biomedical to energy sectors to almost any type of manufacturing, this approach can help extend the life of machine parts, reduce maintenance and replacement costs, and create a more sustainable industrial future.”

This paper discusses experimental and computational results of ultra-low (near-zero) friction of carbon-coated metal deposits on structural steels, Ti and Ni alloys substrates. Macro-scale superlubricity was demonstrated and maintained over several cycles through structurally poorly oriented carbon coatings on metal surfaces.

Carbon nanocrystals with trace variants of graphene were deposited on these metal surfaces using a novel high-temperature biological waste treatment process. The carbon nanocrystals are deformed, planarized and coalesced in the wear tracks to form graphite films, leading to a superlubricant coefficient of friction of ~0.003.

A coating life of ~150,000 cycles with reduced wear rates was achieved on Ni and steel substrates. The experiments were validated with atomistic simulations that provide mechanistic insights into the effects of graphene variants under the observed frictionless conditions.

The underlying mechanisms of coating/substrate interactions that contribute to macroscale superlubricity are elucidated. Implications of the present results are explored for the design of low cost and robust macro superlubricating carbon coatings on metallic substrates. Bio-waste is a carbon source within a circular economy that uses material recycling to reduce the global carbon footprint.

The paper was published by a group of eight materials scientists collaborating across Africa and the Northeastern United States, including Mobin Vandadi, Desmond Edem Primus Klenam, Kwadwo Mensah-Darkwa, Emmanuel Gikunoo, Samuel Kwofie and Nima Rahbar.

“My colleagues and I are extremely proud of this work, especially for the environmental and economic implications it may have,” said Dr. Soboyejo. “We look forward to seeing the advances in friction management technologies that will occur as researchers operationalize these approaches.”