A review on Nanoparticle Application as an Additive in Lubricants

Lubricants are obtained from mineral-based oils or synthetic oils. Due to their limitations, these oils do not meet the standards set by equipment manufacturers. To overcome these limitations, very few but effective additives are included in the base oil formulation, which lead to significant improvements in lubricants' properties, such as anti-oxidation properties, tribological properties, and thermal properties. Additives improve the physical and chemical properties of base oil and reduce wear and friction of moving parts. Nanomaterials have been used as environmentally friendly additives to increase the tribological properties of lubricating oils such as motor oil, industrial oils, grease, etc. Nanomaterials have features such as high surface energy, small size, and thermal stability, which have been used as anti-wear, anti-friction, and high compressibility additives. In this research, the use of nano additives in the lubrication industry, the common oil additives, and specifically the use of nano scale particles to improve the performance of the base oil have been reviewed. Different nanoparticles that have been considered include: Al2O3, TiO2, CuO, and ZnO. TiO2 with a volume fraction of 0.01 has increased the load carrying capacity of round bearings by 40%. It was also found that MoS2 can reduce the friction torque by 33%. By adding 0.08 mass percent of graphene oxide combined with nickel nanoparticles to paraffin oil, the friction coefficient, and wear scar diameter have decreased by 32% and 42%, respectively.