Article updated on 13 May 2020.
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Graphene has been touted for many applications, from construction to electronics, textiles, sports equipment, and many more in between. Graphene is starting to emerge in many industrial sectors as an alternative to the status quo and has started to be used in commercial products. One area that has emerged in the last few years is the use of graphene as a lubricant.
When people often think of lubricants, they think of a fluid that is present in their cars or within heavy machinery. While most of the lubricants in use today are a type of fluid, there is another class known as solid-state lubricants where solid materials have lubricating properties.
Graphene as a class of materials is very versatile as there are many different types, and they have a wide range of useful properties. While many people focus on the conductive properties for electronics or their mechanical strength in structural materials, many have overlooked the range of properties that have enabled graphene to be used as solid lubricant.
So, will solid graphene lubricants replace conventional oils? No-one can say yes or no with absolute certainty, but there is potential for graphene lubricants, as significant progress has been made in the last few years.
Could graphene lubricants be a replacement for conventional oil and fluid lubricants in specific applications? Yes. Will graphene lubricants replace oils in every single application? No. There are many reasons for this, but the main ones are that the properties of graphene lubricants are not suitable for some lubricant applications, and even if they were, their cost would be far too high compared to conventional fluid lubricants. However, they do have the potential to replace oils in specific sectors—with examples in recent years being in the protection of ball bearings and wind turbines.
There are a few different properties that are responsible for graphene being used in/as lubricants. Firstly, graphene has a high mechanical strength, which helps to suppress the wear on a material. Secondly, graphene is highly resistant to chemicals, heat, mechanical stresses, oxygen and moisture. This means that graphene can be used in mechanical systems as a way of slowing down corrosion/oxidation, while not degrading due to its inherent resistant to shear stresses and resistance to the high temperatures that can be generated in these environments.
One area of research I have seen grow from concept to an almost commercially viable reality over the last few years is the use of graphene and carbon nanodiamonds as a solid-state lubricant. It won’t be long until it is available on the market as a lot of funding has gone into this research. The work has come out of the Argonne National Laboratory in the US, and the developments have been showcased every year for the last few years at the events hosted by the National Graphene Association (NGA).
These specially designed systems are a two-component system that acts as a single system to provide lubricating effects. Not only are they known to provide lubricating effects, but they have shown superlubricity effects. These systems are being trialed on metal bearing systems and work by encapsulating the nanodiamonds.
When two surfaces move in the presence of the lubricant, the graphene sheet wraps itself around the nanodiamond, encapsulating it. This enables the graphene-nanodiamond system to lubricate the two surfaces while still being able to move between the two surfaces due to the spherical nature of the nanodiamond. The enhanced graphene system is known to reduce the wear, friction, oxidation, and corrosion between the surfaces and is a very promising area of development.
Incorporating Graphene into Oils
While there is a lot of talk about graphene as a solid-state lubricant, it is also commercially used within oil-based lubricants as an additive. One such example is Graphenoil, produced by IA Coatings, which has shown to induce a lower coefficient of friction, improved lifetime, and reduced corrosion in mechanical systems.
The formulations for these oils have been specifically tailored towards automotive engines and utilize single-layer graphene. The lubricants have been designed to improve the flashpoint of oil to make it less flammable and hazardous inside the engine, as well as for improving fuel economy and engine stability. So, there are areas where graphene lubricants and oils are entering the market, but whether will take over the market remains to be seen.