Effective Lubricant Additives Research Articles

Controllable fabrication of magnesium silicate hydroxide reinforced MoS2 hybrid nanomaterials as effective lubricant additives in PAO

Molybdenum disulfide (MoS2) nanoparticles have poor dispersion stability and poor resistance to extreme pressures, which severely limit their application as lubricant additives. Here, magnesium silicate hydroxide (MSH) reinforced MoS2 hybrid nanomaterials were synthesized by a facile hydrothermal method, and their tribological behaviors as lubricant additives to polyalphaolefin (PAO) were investigated. Results show that the controllable preparation of MSH-MoS2 nanoparticles with different morphologies, compositions, and binding states can be achieved simply by changing the reaction temperature. MoS2 and MSH combine better at the reaction temperature of 220 °C (MM2) because of the edge-pinning effect caused by noncoherent. Due to its abundance of active anchoring sites, MM2 exhibits superior dispersion stability. Importantly, the anti-friction performance, wear-resistance, and last non-seizure load of the friction pairs lubricated in PAO-MM2 are improved by 44.8%, 41.2 %, and 116.6%, respectively. The outstanding tribological behaviors should be credited to the formed robust bilayer tribo-film: the upper layer contains abundant MoS2, providing outstanding anti-friction functionality; whereas the adjacent layer, which is made up of MSH and reaction products of the lubricant additive and substrate, strongly ensures the stability of the first layer.

Dialkyl Dithiophosphate-Functionalized Ti3C2Tx MXene Nanosheets as Effective Lubricant Additives for Antiwear and Friction Reduction

Dialkyl Dithiophosphate-Functionalized Ti₃C₂T_<i>x</i> MXene Nanosheets as Effective Lubricant Additives for Antiwear and Friction Reduction

Nanodiamond Particles as Secondary Additive for Polyalphaolefin Oil Lubrication of Steel-Aluminium Contact.

Nanodiamond (ND) particles are effective lubricant additives. Attention of research has shifted towards investigating the particles as secondary additives. ND particles provide more benefits as secondary additives than as the sole lubricant additive for steel–steel contacts. In this work, the influence of ND particles as secondary additives on oil lubrication of steel–aluminium tribopair (hard–soft contact) was examined. AISI 52100 steel balls were slid against AA2024 aluminium alloy discs, in the presence of polyalphaolefin (PAO) base oil, in boundary lubrication regime (applied normal load: 10 N to 50 N). Primary additives were copper oxide (CuO) and hexagonal boron nitride (h-BN) nanoparticles. The addition of ND particles to PAO, with CuO and h-BN as primary additives, at the lowest applied normal load of 10 N: (i) decreased the volumetric wear of the aluminium discs by 28% and 63%, respectively, and (ii) decreased the coefficient of friction by 15% and 33%, respectively. At the highest applied normal load of 50 N, it: (i) decreased the volumetric wear of the aluminium discs by 20% and 38%, respectively, and (ii) decreased the coefficient of friction by 5.4% and 8%, respectively. ND particles as secondary additives significantly reduce energy loss and power loss as a consequence of an effective reduction in friction during sliding. Unique characteristics of ND particles—such as their (a) physicochemical and thermal properties, (b) ball bearing and polishing effects and (c) synergistic interaction with primary additives to form stable tribofilms—enhance the lubrication performance of steel–aluminium contact. ND particles in combination with h-BN nanoparticles showed the best performance, due to better synergy between the primary additive and the secondary additive. Results from the investigation indicate that ND particles taken as secondary additives in small amount (0.2 wt%) can improve oil lubrication performance of hard–soft contacts in engineering systems.

New Functionality of Ionic Liquids as Lubricant Additives: Mitigating Rolling Contact Fatigue.

Oil-soluble ionic liquids (ILs) have recently been demonstrated as effective lubricant additives of friction reduction and wear protection for sliding contacts. However, their functionality in mitigating rolling contact fatigue (RCF) is little known. Because of the distinct surface damage modes, different types of surface protective additives often are used in lubricants for sliding and rolling contacts. Therefore, the lubricating characteristics and mechanisms of ILs learned in sliding contacts from the earlier work may not be translatable to rolling contacts. This study explores the feasibility of using phosphonium-phosphate, ammonium-phosphate, and phosphonium-carboxylate ILs as candidate additives in rolling-sliding boundary lubrication, and results suggested that an IL could be either beneficial or detrimental on RCF depending on its chemistry. Particularly, the best-performing phosphonium-phosphate IL at 2% addition made a low-viscosity base oil significantly outperform a more viscous commercial gear oil in reducing the RCF surface damage and associated vibration noise. This IL generated a thicker, smoother, and more homogeneous tribofilm compared with commercial additives, which is likely responsible for the superior RCF protection. Results here suggest good potential for using appropriate IL additives to allow the use of low-viscosity gear and axle fluids for improved efficiency and durability.

Surface Modification of MoS2 Nanosheets as Effective Lubricant Additives for Reducing Friction and Wear in Poly-α-olefin

Herein, MoS2 nanosheets (MoS2) densely modified with n-octadecyl mercaptan (NOM) are used as effective friction-reducing and antiwear additives. A facile and green strategy is employed to prepare t...

Tribological properties of nano cellulose fatty acid esters as ecofriendly and effective lubricant additives

Three cellulose esters, cellulose acetate-butyrate, cellulose acetate-octanoate, and cellulose acetate-laurate, were synthesized by both conventional co-reactant reaction (CCR) and mechanical activation-assisted co-reactant reaction (MACR) methods, and the corresponding nano-cellulose esters were prepared by high pressure homogenization to comparatively investigate their tribological properties as lubricant additives in liquid paraffin base oil. MACR method was more effective than CCR method for preparing long chain cellulose esters, and the MACR-prepared cellulose esters were more easily homogenized to smaller nanoparticles. Tribological testing indicated that anti-wear and load-carrying properties of the lubricants were significantly enhanced with nano-cellulose esters as additives compared to those of pure liquid paraffin, especially the MACR-prepared long chain cellulose esters. The wear scar diameter on worn surface of the steel balls reduced with the increase in degree of substitution (DS) and chain length of long chain substituents and the decrease in size dimension of nano-cellulose esters. The polar ester carbonyl groups, unesterified hydroxyl groups, and long hydrocarbon alkyl chains in nano-cellulose esters could lead to the formation of a film layer in the steel/steel contact surfaces for protecting the metals from friction and wear, which gave the lubricants with good anti-wear and load-carrying properties. The nano-cellulose esters with high DS and long chain substituents prepared by MACR technology as ecofriendly additives exhibited better lubricating ability. Nano-cellulose esters with high DS of long chain substituents prepared by mechanical activation-assisted co-reactant reaction technology used as ecofriendly lubricant additives in base oil showed good anti-wear and load-carrying properties, ascribing to the formation of a film layer in the steel/steel contact surfaces for protecting the metals from friction and wear.

Tribological Performance of Phosphonium Ionic Liquids as Additives in Lithium Lubricating Grease

Three oil–miscible phosphonium ionic liquids with different structures were synthesized and used as additives for a Poly Alpha Olefin 10 (PAO 10) lithium lubricating grease. Different from other additives, the ionic liquids participated in saponification and were trapped in the entanglement network formed by the thickener. The effects of the ionic liquids on the rheological properties of lithium lubricating grease were characterized through a small-amplitude oscillatory shear (SAOS) measurement. The tribological performances of the lubricating greases were determined on a four-ball friction tester. The addition of phosphonium ionic liquids caused a decrease in the storage (G′) and loss (Gʺ) modulus of lubricating grease. However, the ionic liquids were found to be effective lubricant additives for improving the friction-reducing and antiwear properties of PAO 10 lithium lubricating grease.

Nano and micro structures produced from carbon rich fly ash as effective lubricant additives for 150SN base oil

Lubricant oils in cars engines are essential components for reducing friction and fuel consumption. The lubrication process can be improved by including effective additives. Carbon nanostructures have been recognized as excellent additives in lubricant oils. Amongst them carbon nanotubes (CNTs) produced from carbon rich fly ash, are found to have excellent tribological properties in the sunflower base oil. In this work, these CNTs along with other micro and nanostructures produced from carbon rich fly ash are tested as lubricant additives in the 150SN base oil. The impregnated oils with these additives are evaluated to reduce the friction between two metallic surfaces using the ball-on-disk tribometer. The obtained results showed that CNTs of fly ash have significantly reduced the frictional coefficient by around 25% at a concentration of 0.1wt%. This result is much better than that of the other fly ash micro and nanostructures produced by sonication and ball milling techniques. It is also compared with that of a commercial multiwall CNTs and is found to be superior. The friction coefficient values are investigated as a function of load and temperature. Moreover, the rheological behavior is also studied for the pure and 0.1wt% CNTs-impregnated oil. No significant changes are observed in the viscosity of the impregnated oil. The present CNTs of carbon rich fly ash have been proved to be effective additives for the 150SN lubricant oil, and might be useful for variety of lubricants.

Carbon nanotubes of oil fly ash integrated with ultrathin CuO nanosheets as effective lubricant additives

Carbon nanomaterials have been reported to be effective as lubricant additives. Amongst them carbon nanotubes (CNTs) produced from oil fly ash, were found to have excellent tribological properties. In this work these CNTs were further improved for their suspension and tribological performance by integrating them with ultrathin non-agglomerated CuO nanosheets produced by the microwave technique. The mixture of these nanostructures was evaluated as a lubricant oil additive to reduce the friction between two metallic surfaces. The ball-on-disk tribometer was used to measure the frication coefficient. Samples with different concentrations of this mixture in the range 0–0.2wt% were evaluated as lubricant additives for the base sunflower oil. The obtained results were compared with those of commercial well-known carbon nanostructures like single wall nanotubes, multiwall nanotubes and graphene. The results of fly ash CNTs integrated with CuO nanosheets were found to be superior as they could significantly reduce value of the friction coefficient by approximately 43%. The suspension with very small concentration i.e. 0.05wt% could stay for months without showing any precipitation. These results suggest that the mixture of fly ash CNTs and CuO nanosheets is ideal lubricant additives and may be used for variety of lubricants.

Oil-Soluble Polymer Brush Grafted Nanoparticles as Effective Lubricant Additives for Friction and Wear Reduction.

The development of high performance lubricants has been driven by increasingly growing industrial demands and environmental concerns. Herein, we demonstrate oil-soluble polymer brush-grafted inorganic nanoparticles (hairy NPs) as highly effective lubricant additives for friction and wear reduction. A series of oil-miscible poly(lauryl methacrylate) brush-grafted silica and titania NPs were synthesized by surface-initiated atom transfer radical polymerization. These hairy NPs showed exceptional stability in poly(alphaolefin) (PAO) base oil; no change in transparency was observed after being kept at -20, 22, and 100 °C for ≥55 days. High-contact stress ball-on-flat reciprocating sliding tribological tests at 100 °C showed that addition of 1 wt % of hairy NPs into PAO led to significant reductions in coefficient of friction (up to ≈40 %) and wear volume (up to ≈90 %). The excellent lubricating properties of hairy NPs were further elucidated by the characterization of the tribofilm formed on the flat. These hairy NPs represent a new type of lubricating oil additives with high efficiency in friction and wear reduction.

Oil‐Soluble Polymer Brush Grafted Nanoparticles as Effective Lubricant Additives for Friction and Wear Reduction

AbstractThe development of high performance lubricants has been driven by increasingly growing industrial demands and environmental concerns. Herein, we demonstrate oil‐soluble polymer brush‐grafted inorganic nanoparticles (hairy NPs) as highly effective lubricant additives for friction and wear reduction. A series of oil‐miscible poly(lauryl methacrylate) brush‐grafted silica and titania NPs were synthesized by surface‐initiated atom transfer radical polymerization. These hairy NPs showed exceptional stability in poly(alphaolefin) (PAO) base oil; no change in transparency was observed after being kept at −20, 22, and 100 °C for ≥55 days. High‐contact stress ball‐on‐flat reciprocating sliding tribological tests at 100 °C showed that addition of 1 wt % of hairy NPs into PAO led to significant reductions in coefficient of friction (up to ≈40 %) and wear volume (up to ≈90 %). The excellent lubricating properties of hairy NPs were further elucidated by the characterization of the tribofilm formed on the flat. These hairy NPs represent a new type of lubricating oil additives with high efficiency in friction and wear reduction.

Temperature effect of friction and wear characteristics for solid lubricating graphite

Graphite is one of the effective lubricant additives due to its excellent high-temperature endurance and self-lubricating properties. In this study, wear behavior of graphite used as sealing materials to cut off hot gas is evaluated at room and elevated temperature. Wear occurs on graphite seal due to the friction of driving shaft and graphite. Thus, a reciprocating wear test to evaluate the wear generated for the graphite by means of the relative motion between a shaft material and a graphite seal was carried out. The friction coefficient and specific wear rate for the changes of applied load and sliding speed were compared under different temperature conditions considering the actual operating environment. Through SEM observation of the worn surface, the lubricating film was observed and compared with test conditions.

DOSS– Based QAILs: As Both Neat Lubricants and Lubricant Additives with Excellent Tribological Properties and Good Detergency

DOSS– (dioctyl sulfosuccinate) based quaternary ammonium ionic liquids (QAILs) were synthesized and used as both neat lubricants and lubricant additives. The influence of structure on their miscibility, thermal stability, and tribological property was discussed. These QAILs are low cost as compared with conventional halogen-containing ionic liquids (ILs). They are noncorrosive and hydrolysis stable because of their halogen-free characteristics. The tribological properties of these QAILs as neat lubricants for steel/steel and steel/copper contacts are found to be better than conventional halogen-containing ILs 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (L-F104) and far better than traditional synthetic lubricant poly-α-olefin (PAO). Moreover, oil-soluble ILs were obtained by properly adjusting the chain length and cation asymmetry of these QAILs, which can be easily dissolved in nonpolar synthetic-oil PAO. They are found to be effective lubricant additives for improving the friction-redu...