Written by BAALLA Fatima-ezzahra
Engines, gear assemblies, and other equipment are so crucial and play bigger roles in the industry to protect those components from friction and wear. It is essential to interfere with lubricants to decrease downtime, increase life span, and lower maintenance costs. Lubricants are formulated with special additives to meet the industry requirements and to enhance the performance of operating conditions.
There is a hyphenated relationship between friction and lubrication. Friction refers to the force that resists motion when two surfaces are in contact with each other. While lubrication means the use of a substance called lubricant either a fluid or a solid to prevent moving parts from rubbing. It has shown that excessive friction can cause asperities to weld together and break off as the parts move and this wears down the metal surfaces, it also leads to an increase in heat and causes damage to the component. In this respect, there is a tendency to alleviate friction to increasing life components.
The key objective is to reduce friction which leads researchers to think outside the box and find new solutions that will help to provide a reliability component by including tiny materials at the nanoscale to enhance the tribological properties giving rise to low friction.
This article sheds light on the contribution of nanomaterials and how they can improve the performance of lubricants.
What’s so super in Nanomaterials?
Since early times, humankind has dealt with all sorts of materials but no one expects to use tiny small objects in numerous applications. Those small materials have become the building block of high-tech systems. But let’s first discuss the definition of a nanomaterial. According to ISO TS 80004-1, a nanomaterial is a material with at least one external dimension at the nanoscale, i.e. between approximately 1 and 100 nm, or with an internal or surface structure at the nanoscale.
One nanometer = one billionth of a meter = 0.000000001 meters.
It showcases that nanomaterials are infinitesimally small to be seen with the help of conventional microscopy though they can pack a big punch due to the small size. This makes it possible to emerge into many areas in science.
Nanomaterials can be classified based on many criteria, for example on their origin, if they are hand-made or synthesized. But the most important classification that is usually taken into account is dimensionality.
What's most impressive about those materials, it’s the possibility to fine-tune the properties by changing the size. It seems counterintuitive. How can small objects have a larger surface area? But that’s true. The smaller the material is, the larger the surface area, and the contact matters because the more contact could occur between a material and its surrounding. This leads them to be good catalysts due to the faster rate of surface-level reactions and this is an advantage that can be used in a very wide range of applications.
How nanomaterials might boost the performance of lubricants?
The importance of nanomaterials, more precisely 2D materials, is their nanosheet shape. This makes it possible to penetrate the interspaces of the moving parts. And the continuous movement of those rubbing surfaces will generate the required shear stress resulting in the sliding of interlayers in the nanosheets which leads to a decrease in wear and friction. A tribofilm will form in the sliding areas protecting the interacting parts from direct contact. Then, the rupturing of the protective film and the formation of a new one as a result of a tribochemical reaction generated between the contact surfaces between the substrate and the lubricant. Furthermore, as sliding continues, producing high temperatures leads to melting the nanosheets and filling up the holes and cracks formed on the worn surfaces in the contact parts.
The employment of nanomaterials as solid lubricants or nano additives has witnessed outstanding properties such as antiwear, anticorrosion, antifriction due to their unique attributes ( low coefficient of friction and wear rates). Thus, explaining why 2D materials such as MoS2, WS2 have been extremely used in lubricant technology.