Experimental Analysis of Lubricating Oil Using Nanoparticles as Modifiers for Tribological Properties
Nowadays nanoscience is one of the most expansively developing spheres of world’s science and its achievements can be applied in different areas of science and technology. Nanomaterials as an example which are in the form of so called nanostructures (nanotubes, nanowires, Nano powders and others) which are widely used in many human activity fields- from cancer treatment to engineered textiles or energy storage to rocket explosives and propellant . In upcoming decades various new fields of nanostructures application will arise. One of them seems to be the unexplored area of nanostructures use as additives modifying properties (especially tribological) of lubricating or cutting oils.
Nanotechnology is regarded as the most
revolutionary technology of the 21st century.
It can be used in many fields of material science into a new era. In recent years numerous investigations have been carried out on the tribological properties of lubricants with different nanoparticles added in it. A number of papers from different authors all over the world have concluded that it is significantly effective to add nanoparticles to lubricant for reducing wear and friction.
Among those that were added into oils, MoS2 nanoparticles have received much attention and exhibited excellent applications for their good friction reduction and wear resistance properties. The interfacial conditions which affect the reduction of wear are geometry, normal load, sliding speed, relative surface motion, surface roughness, vibration and lubrication. In addition, anti- wear properties, load-carrying capacities and friction reduction are mainly controlled by the chemical additives in lubricating fluid under boundary lubrication conditions.
As the addition of a dispersing agent or the use of a surface modification preparation technique stabilizes the nanoparticles, inorganic nanoparticles have received considerable attention in the lubrication field. Nanoparticles have received considerable attention because of their special physical and chemical properties. The preparation of organic–inorganic complex nanoparticles was causing more interest in science and industry.
Though, some of them were analyzed and studied as water base lubrication additives. In recent years, with the development of nanomaterial, many scientific researchers added nanoparticles into lubricating oils to improve extreme pressure, anti-wear, friction reducing properties, the efficiency and service life of machinery. The application of advanced nanomaterials has played an active role in improving and reforming traditional lubrication technology.
When nanopartilces are used as additives in lubricants the anti-wear mechanism can be explained in three various ways: nanoparticles can be melted and welded on the rubbing surface, reacted with the specimen to form a protective layer, or tribo-sintered on the surface. However, some authors state that nanoparticles can also act as small bearings on the rubbing surfaces. Nanoparticles get pierced in lubricated EHD contacts to form a boundary film. These nanoparticles are entrained into sliding contacts only when the film thickness is smaller than the particle size contributing to the film thickness. The already discussed anti-wear mechanisms of the nanoparticles take place only under mixed and boundary lubrication. Results show that nanoparticles can improve the tribological properties of the base oil, displaying good friction and wear reduction characteristics even at concentrations below 1 wt%. Although, they do not estimate the tribological behavior of coated nanoparticles used as lubricant additives with the non-coated ones.
Abstract - Nanoparticles are proved to be useful as modifiers in the engine oil to enhance its tribological properties to reduce wear and friction of the engine. In this research molybdenum disulphide (MoS2) and copper oxide (CuO) nanoparticles are added to engine oil SAE20W50 and tribological properties are analyzed. Test samples were made with varying percentage of MoS2 and CuO nanoparticles in engine oil (0.25, 0.5 and 1 wt. %). Redwood viscometer was used to carry out viscosity tests for different samples at three different temperatures. The flash point and fire point tests were carried on Cleveland open cup apparatus. The experimental observations show that MoS2, CuO nanoparticles added in engine oil exhibits good friction reduction and anti- wear properties and also decreased the coefficient of friction as compared with standard engine oil without MoS2, CuO nanoparticles. This tribological behavior is closely related to the deposition of nanoparticles on the rubbing surfaces
Key Words: MoS2, CuO nanoparticles, tribological properties, engine oil, friction coefficient, wear