Lubricants with Nanoparticle-Improved Functionalities

Lubricating oils can greatly benefit from nano-additives, which help to reduce friction and wear. It is however crucial, that nano-additives such as nanoparticles, graphene monolayers or core-shell nanospheres are uniformly and single-dispersed in the lubricant. Ultrasonic dispersion has been proven as reliable and efficient mixing method, providing homogeneous nanoparticle distribution and preventing aggregation.

How to Disperse Nano-Additives in Lubricating Fluids? – With Ultrasonics!

Using nano-additives in lubricants is considered as one of the most effective methods to improve tribological characteristics reducing friction and wear. Such tribological improvement greatly enhances energy conservation, emission reduction, thereby lowering environmental impact.
The challenge of nano-improved lubricants lies in the mixing: Nanomaterials such as nanoparticles or crystalline nano cellulose require focused high-shear mixers that disperse and disentangle the nano-materials uniformly into single particles. Creating unique energy-dense fields, ultrasonication using high-power ultrasound probes has been proven superiority in nanomaterial processing and is thereby the established method for nano-dispersions.
Molseh et al. (2009) showed that the dispersion stability of three different nanoparticles (molybdenum disulfide (MoS2), tungsten disulfide (WS2), and hexagonal boron nitride (hBN)) in CIMFLO 20 with ultrasonic treatment was better than that with mechanical shaking and stirring. As ultrasonic cavitation creates unique energy-dense conditions, probe-type ultrasonication excels conventional dispersion techniques in effectiveness and efficiency.
Nanoparticles characteristics such as size, shape, and concentration are influencing their tribological properties. Whilst ideal nano-size varies in dependence of the material, most nanoparticles show highest functionalities in the range of ten to hundred nanometers. Ideal concentration of nano-additives in lube oil is mostly between 0.1–5.0% .
Oxide nanoparticles such as Al2O3, CuO or ZnO are widely used as nanoparticles improving the tribological performance of lubricants. Other additives include ashless additives, ionic liquids, borate esters, inorganic nanomaterials, carbon-derived nanostructures like carbon nanotubes (CNTs), graphite and graphene. Specific additives are used in order to improve specific properties of lube oils. For instance, wear preventative lubricants contain extreme pressure additives such as molybdenum disulfide, graphite, sulfurized olefins and dialkyldithiocarbamate complexes or antiwear additives such as triarylphosphates and zinc dialkyldithiophosphate.
Ultrasonic probe-type homogenizers are reliable mixers and are used for the formulation of high-performance lubricants. Renown as superior when it comes to the preparation of nano-sized suspensions, sonication is highly efficient for the industrial manufacturing of lube oils.

Ultrasonic dispersion of Aluminium oxide (Al2O3) results in a significant particle size reduction and uniform dispersion.

Manufacturing of Lubricants with Nano-Additives

For the production of nano-reinforced lubricating oils, adequate nano-material and a powerful, efficient dispersion technique are crucial. Without reliable and long-term stable nano-dispersion, there cannot be manufactured a high-performance lubricant.
Ultrasonic mixing and dispersing is an established method for the production of high-performance lubricants. The base oil of lubricants is reinforced with additives such as nanomaterials, polymers, corrosion inhibitors, antioxidants and other fine aggregates. Ultrasonic shear forces are highly efficient in providing a very fine particle size distribution. Ultrasonic (sonomechanical) forces are capable to mill even primary particles and are applied to functionalize particles, so that the resulting nanoparticles offer superior characteristics (e.g. surface modification, core-shell NPs, doped NPs).
Ultrasonic high-shear mixers can greatly help to manufacture high-performance lubricants efficiently!

Novel Nano-Additives in Lubricating Oils

Novel nano-sized additives are developed to further improve functionalities and performance of lubricating oils and greases. For instance, cellulose nano-crystals (CNCs) are researches and tested for the formulation of green lubricants. Zakani et al. (2022) demonstrated that – in comparison to unsonicated lubricating suspensions – sonicated CNC lubricants could decrease COF (coefficient of friction) and wear by almost 25 and 30% respectively. Results of this study suggest that ultrasonication processing can significantly improve lubrication performance of CNC aqueous suspensions.

High-Performance Ultrasonic Dispersers for Lubricant Manufacturing

When nano-addititives are used in industrial manufacturing processes such as the production of lubricating oils, it is crucial that dry powders (i.e., nanomaterials) are homogeneously mixed into a liquid phase (lube oil). Nano-particle dispersion requires a reliable and effective mixing technique, which applies enough energy to break agglomerates in order to unleash the qualities of nano-scale particles. Ultrasonicators are well known as powerful and reliable dispersers, therefore used to deagglomerate and distribute various materials such as aluminium oxide, nanotubes, graphene, minerals and many other materials homogeneously into a liquid phase such as mineral, synthetic or vegetable oils. Hielscher Ultrasonics designs, manufactures and distributes high-performance ultrasonic dispersers for any kind of homogenization and deagglomeration applications.
Contact us now to learn more about ultrasonic dispersion of nano-additives in lubricants!

The table below gives you an indication of the approximate processing capacity of our ultrasonicators: