Lubricating Oil Additives Research Articles

MoS2 nanoparticles grown on carbon nanomaterials for lubricating oil additives

In this study, the nanocomposites of MoS2 nanoparticles (NPs) grown on carbon nanotubes (MoS2@CNT), graphene (MoS2@Gr), and fullerene C60 (MoS2@C60) were synthesized, characterized, and evaluated for potential use as lubricant additives. By using the benefit of the synergistic effect between MoS2 and carbon nanomaterials (CNMs), these nanocomposites can be well dispersed in polyalkylene glycol (PAG) base oil and show superior stability compared with pure MoS2 NPs. Moreover, the dispersions of MoS2@CNT, MoS2@Gr, and MoS2@C60 added in PAG have noticeably improved friction reducing and antiwear (AW) behaviors at elevated temperature for comparison with that of PAG and PAG containing CNT, Gr, C60, and MoS2 NPs, respectively. The enhanced lubricating properties of these nanocomposites were also elucidated by exploring the tribofilm formed on the disc.

Addition of yellow grease to grain-based diets and taiwan grass on growth performance of finishing hair lambs

Growing lambs were used to evaluate the effects of dietary inclusion of yellow grease (YG) on performance and carcass yield. Sixteen male hair lambs were assigned randomly to one of two diets with 0 or 30 g YG/kg DM and similar energy and protein content. Lambs underwent adaptation to diets for 12 d and fasting for 75 d. Dietary inclusion of YG did not affect growth performance or feed intake. Feed conversion, hot and cold carcass weight and yield improved by YG. The dietary addition of 30 g YG/kg DM allowed reducing the proportion of dietary grain without causing harmful effects on growth performance and feed intake but improving carcass dressing in finishing hair lambs. Given that its inclusion in grain-based diets improved carcass weights and yield. We can conclude that YG would be an efficient alternative energy source for hair lambs under tropical conditions. Nevertheless, further research is required to determine the effect of YG on meat and carcass quality.

Nonylphenol exposure affects mouse oocyte quality by inducing spindle defects and mitochondria dysfunction

Nonylphenol (NP) is a chemical raw material and intermediate which is mainly used in the production of surfactants, lubricating oil additives and pesticide emulsifiers. NP is reported to be toxic on the immune system, nervous system and reproductive system due to its binding to estrogen receptors. However, the toxicity of NP on mammalian oocyte quality remains unclear. In present study, we explored the effects of NP exposure on mouse oocyte maturation. Our results showed that 4 weeks of NP exposure increased the number of atresia follicles and decreased oocyte developmental competence. Transcriptomic analysis indicated that NP exposure altered the expression of more than 800 genes in oocytes, including multiple biological pathways. Subcellular structure examination indicated that NP exposure disrupted meiotic spindle organization and caused chromosome misalignment. Moreover, aberrant mitochondrial distribution and decreased membrane potential were also observed, indicating that NP exposure caused mitochondria dysfunction. Further analysis showed that NP exposure resulted in the accumulation of reactive oxygen species (ROS), which causes oxidative stress; and the NP-exposed oocytes showed positive Annexin-V signal, indicating the occurrence of early apoptosis. In summary, our results indicated that NP exposure reduced oocyte quality by affecting cytoskeletal dynamics and mitochondrial function, which further induced oxidative stress and apoptosis in mice.

Competitive Adsorption of Lubricant Base Oil and Ionic Liquid Additives at Air/Liquid and Solid/Liquid Interfaces

Oil-soluble ionic liquids (ILs) have been proved as effective additives in lubricant oils through tribological experiments and post-test analytical analyses. In this study, surface structures of lubricant base oil, oil-soluble ILs, and their mixtures at the air/liquid and solid/liquid interfaces have been studied using sum frequency generation (SFG) vibrational spectroscopy. At the air/base oil and air/IL interfaces, the alkyl chains of the studied compounds were shown to be conformationally disordered and their terminal methyl groups point outward at the liquid surface. The base oil dominates the air/(base oil + IL) interface due to its higher surface excess propensity and larger bulk concentration. At the solid (silica) surface, ILs adopt a structure with their charged headgroups in contact with the silica surface, while their alkyl chains are more conformationally ordered or packed compared to the air/IL interface. At the interface between silica and (base oil + IL) mixtures, ILs also preferentially adsorb to the silica surface with their layer structures somewhat different from those of ILs alone. These results showed that ILs can adsorb onto the solid surface even before tribological contacts are made. The insights obtained from this SFG study provide a better understanding of the role of ionic liquids in lubrication.

Tribological Investigation of Multilayer Graphene as Lithium Grease Additives

As an advanced antiwear and friction reducing material, graphene has been widely studied and applied in many fields. In this study, the tribological characteristics of lithium grease with multilayer graphene (MLG) additive were studied on a four-ball tester. The micro-morphologies and elemental distributions of the wear surfaces of steel balls were identified by FESEM and EDAX. The tribological properties of grease were obviously improved by MLG additive. When the content of MLG was 0.1 wt%, the improvement effect was the best. The coefficient of friction and the wear scar diameter (WSD) decreased by 22.6% and 9%, respectively, at 686 N and 1450 rpm as compared to the original lithium grease. Because of the layered structure of graphene along with its high strength and surface activity, a layer of lubricating film which was favorable for improving the anti-friction and anti-wear property of the friction pair was formed on the friction surface during the friction process.

Nitrogen-Phosphorus Codoped Carbon Nanospheres as Lubricant Additives for Antiwear and Friction Reduction

Nitrogen and phosphorus doping have been proven to be effective strategies for improving the tribological properties of carbon-based materials when used as lubricating oil additives. Herein, an efficient strategy is demonstrated for the preparation of nitrogen and phosphorus codoped organic carbon nanospheres (denote as N, P@CN) via a template-free interfacial copolymerization combined with ammonium hypophosphite-assisted carbonization. The N and P are found to be homogeneously distributed through the entire carbon shell. The tribological properties of as-prepared materials as base oil additives under different test conditions were evaluated. The as-prepared N, P@CNs exhibit good dispersibility and stability in base oil due to the presence of many organic functional groups. Moreover, they are considered to be thermal stable at elevated temperatures, and the existing robust structure makes them favorable as lubricant additives. The experiment results show that the friction reduction and wear resistance abilities of N, P@CNs were superior to that of pure base oil, because N, P@CNs can induce tribo-chemical reactions to form a protective film on the interfaces due to the combined effect of nitrogen and phosphorus. The obtained N, P@CNs could increase the load carrying capacity of base oil from 250 N to 1050 N. The coefficient of friction can be reduced to 0.08, and the corresponding wear volume loss can be decreased by 90%. These findings open up a possibility to prepare environmentally friendly lubricant additives, such as carbon nanospheres doped with other elements, to achieve excellent antiwear and friction-reducing characteristics.

Tribological behavior of layered double hydroxides with various chemical compositions and morphologies as grease additives

The layered double hydroxide (LDH) is a kind of natural mineral, which can also be manually prepared. It has been practically applied in various fields due to its unique crystal structure and diversity of composition, size, and morphology. In this work, LDHs with different chemical compositions (Co2+, Mg2+, Zn2+, and Ni2+) and topographical features (flower-like, spherical, and plate-like) were successfully prepared by controlling the reaction conditions. Then, they were mechanically dispersed into base grease and their tribological properties were evaluated by a ball-on-disk tester under a contact pressure of 2.47 GPa. It was found that the variation of morphology, instead of chemical composition, had great influence on the tribological performance. The “flower-like” LDH sample with high specific surface area (139 m2/g) was demonstrated to show the best performance. With 1 wt% additive, the wear volume was only about 0.2% of that lubricated by base grease. The tribofilm with unique microscopic structure and uniform composition was derived from tribochemical reaction between LDH additives and sliding solid surfaces, effectively improving tribological properties of the lubrication system. This work provided the guidance for optimizing lubricant additives and held great potential in future applications.

Wood-Powder-Template-Based Syntheses and Tribology of Copper Oxide Particles as Lubricating Oil Additives

Wood-Powder-Template-Based Syntheses and Tribology of Copper Oxide Particles as Lubricating Oil Additives

Comparative Study on the Effect of Different Lubricating Oil Additives on the Tribological Properties of Bearing Steel

Comparative Study on the Effect of Different Lubricating Oil Additives on the Tribological Properties of Bearing Steel

The Application of Nano-MoS2 Quantum Dots as Liquid Lubricant Additive for Tribological Behavior Improvement.

Molybdenum disulfide quantum dots (MoS2 QDs) are a promising lubricant additive for enhanced engine efficiency. In this study, MoS2 QDs were used as lubricating oil additives for ball-on-disc contact and had adequate dispersity in paroline oil, due to their super small particle size (~3 nm). Tribological results indicate that the friction coefficient of paroline oil with 0.3 wt.% MoS2 QDs reached 0.061, much lower than that of pure paroline oil (0.169), which is due to the formation of a stable tribo-film formed by the MoS2, MoO3, FeS, and FeSO4 composite within the wear track. Synergistic lubrication effects of the tribo-film and ball-bearing effect cooperatively resulted in the lowest friction and wear.

Effects of Lubricating Oil Additives on the Microphysical Properties of Diesel Exhaust Particulate Matter

ABSTRACT In this work, experiments were performed on a diesel engine bench using different experimental fuels prepared by mixing diesel with three lubricating oil additives (LOAs), namely, an antioxidant, a detergent and a foam inhibitor. Diesel exhaust particulate matter (DEPM) samples were subsequently collected. The effects of the LOAs on the micromorphological and microstructural characteristics of the DEPM and its degree of graphitization were investigated using a combination of analytical methods (scanning electron microscopy, transmission electron microscopy and Raman spectroscopy) in conjunction with image processing software. The results showed the following: The DEPM diameter was determined by the polycyclic aromatic hydrocarbon (PAH) content of the fuel. Unburned PAHs caused the organic matter component of the DEPM to precipitate between the lamellae of its primary carbon particles (PCPs). The addition of the antioxidant to the fuel resulted in increased chemical heterogeneity of the DEPM. Furthermore, the D peak in the Raman spectrum of this DEPM had the highest intensity. The DEPM generated from combustion of the foam inhibitor-diesel fuel had the largest average PCP crystallite size; the addition of the foam inhibitor increased the degree of graphitization of the DEPM, and the graphite crystallites in this DEPM were the largest (4.65 nm). The DEPM generated from the combustion of the detergent-diesel fuel had the largest PCP interlayer spacing (mainly in the range of 0.42–0.44 nm). The LOAs did not significantly impact the C-C bond length in the DEPM graphite lattice.

Synthesis of Magnetorheological fluid Compositions for Valve Mode Operation

Abstract Smart materials such as Magnetorheological Fluids (MRF) have become sought-after material in wide ranging applications due to the ability to change properties in a controlled manner under application of stimulation such as a variable current, magnetization, heat, force, stress and deformation. Magnetorheological fluids in the rheological fluid domain has found use due to its ability to change its shear strength based on the applied magnetic field. Magnetorheological fluids are composed of magnetizable micron sized iron particles and a non-magnetizable base/ carrier fluid. The shear strength of commercially available MRF varies from 0 to 100kPa under the effect of the magnetic field. In a valve mode, the Magnetorheological damper (MR Damper or MRD), the MR fluid flows between two-fixed poles, which are parallel to each other. When the fluid flows between them, due to the applied magnetic field the magnetic particles align themselves in a chain form (on state) which is easily reversible when the field is removed (off state). Physical change of the fluid from liquid to semi-solid is controlled by the magnetic field, which makes the fluid a reliable member in active vibration control applications. In this study, two types of magnetizable particles (Carbonyl iron (CI) and Electrolytic iron (EI)) are taken and characterized using an Anton Paar MCR 702 rheometer set-up, in on and off states. To overcome issues like sedimentation, agglomeration and corrosion of the MR fluid, the iron particles are coated with natural gum like guar and xanthan, to the carrier fluid grease and other thixotropic additives are added. The addition of grease and thixotropic additives will inhibit the microbiological degradation of natural gum over an extended period. These engineered MR fluids are then used to analyze the performance of designed and developed stand-alone MR damper, which is tested using an electro-dynamic shaker. The response and damping performance of the MR Damper is analyzed with controlled changes in variables including percentage of additives in MR fluid & magnetization values

Tribology Properties of Synthesized Multiscale Lamellar WS2 and Their Synergistic Effect with Anti-Wear Agent ZDDP

The microscale/nanoscale lamellar-structure WS2 particles with sizes of 2 µm and 500 nm were synthesized by solid-phase reaction method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The synergies between microscale/nanoscale WS2 particles and ZDDP as lubricating oil additives was evaluated by means of UMT-2 tribometer at room temperature. The wear scars were examined with SEM and electron-probe micro-analyzer (EPMA). The results show that the anti-wear properties were improved and the friction coefficient was greatly decreased with the simultaneous addition of WS2 particles and ZDDP, and the largest reduction of friction coefficient was 47.2% compared with that in base oil. Moreover, the presence of ZDDP additive in the lubricant further enhances the friction-reduction and anti-wear effect of microscale/nanoscale WS2. This confirms that there is a synergistic effect between WS2 particles and ZDDP.

Investigations on Graphene Platelets as Dry Lubricant and as Grease Additive for Sliding Contacts and Rolling Bearing Application

In recent years, graphene-based lubrication was in the focus of nano- and microtribological studies. While the sliding properties of graphene based dry lubrication were previously investigated on the nano- and micro-scale, few studies can be found in the literature for the application of graphene as an additive to oil and grease in rolling contacts. In order to apply graphene platelets as dry lubricants and as grease additives in machine elements, tests were carried out on a rolling bearing test rig under typical load conditions. For these investigations, multilayer graphene platelets of varied staple thickness were functionalized on angular contact ball bearing surfaces as a dry lubricant, which forms a thin film. In addition, bearings were lubricated with grease containing graphene platelets. In this case, a small ratio of graphene was dispersed with grease. The graphene platelets were divided into three groups of different thickness: 2 nm, 6–8 nm, and 11–15 nm. Additionally, the tests were compared to graphite nanoparticles (spheres with a size of 3–4 nm) as dry lubricant and graphite-containing grease. The experimental studies were carried out under oscillating motion. The respective load in the tribological contact was 1.5 GPa. During the tests, the pivoting angle was measured by utilizing a rotary encoder. In addition, the friction torque was recorded under a frequency of 0.2 Hz. As the balls’ velocity at the reversal point is zero, the lubrication conditions are critical. The dry lubricated bearings were compared to grease lubricated bearings. Additionally, the frictional properties of the respective greases were investigated by applying a sliding tribometer. In this case, a ball rotates against three contact planes, which causes a tribological contact under a contact pressure of 1 GPa. It was shown that applying graphene as a dry lubricant and as a grease additive under rolling contact conditions reduces friction significantly.

Tribological Performance of Non-halogenated Phosphonium Ionic Liquids as Additives to Polypropylene and Lithium-Complex Greases

Four non-halogenated ionic liquids (ILs) with trihexyl(tetradecyl)phosphonium cation are tested as lubricant additives to polypropylene (PP) and lithium-complex (LiX) greases. In pin-on-disk tests at elevated temperatures, the addition of an IL with bis(oxalato)borate ([BOB]) anion reduces wear by up to 50% when compared to the neat LiX base grease; an IL with bis(mandelato)borate ([BMB]) anion reduces friction by up to 60% for both PP and LiX. Elemental analysis reveals that oxygen-rich tribofilms help to reduce wear in case of [BOB], while the friction reduction observed for [BMB] is likely caused by adsorption processes. We find that temperature has a pronounced effect on additive expression, yet additive concentration is of minor importance under continuous sliding conditions. In contrast, rolling-sliding experiments at 90 °C show that the traction performance of LiX grease is dependent on additive concentration, revealing a reduction in traction by up to 30 and 40% for [BMB]- and [BOB]-containing ILs at concentrations of 10 wt%. Finally, an IL with dicyanamide anion reduces friction and increases wear in pin-on-disk tests at room temperature, while an IL with bis-2,4,4-(trimethylpentyl)phosphinate anion increases wear, showing only limited potential as grease additives. Overall, this work demonstrates the ability of non-halogenated ILs to significantly extend grease performance limits.

In-silico molecular design and dynamic binding energy assessments of some multifunctional lubricating oil additives

Alternatives multifunctional lubricant additives have been proposed by many researchers to replace long-time use of multifunctional lubricant additive, Zinc-dialkyl-dithiophosphate (ZDDP). Quantitative Structure Properties Relationships (QSPR) and dynamics molecular simulations are in-silico methods used for preserving resources and accelerate the process of designing better molecules that can halt the wearing and friction of sliding interfaces by serving as wear and friction-resistant. Six novel anti-wear and anti-friction (multifunctional) lubricant additives with improved properties were successfully designed. The dynamic binding energies and dynamic binding temperatures calculated from the dynamics molecular simulations investigation uncovered that all the designed compounds can bind dynamically to the surface of the steel and DLC during the lubrication process thereby protecting the steel or DLC surfaces against wearing under high temperatures. Therefore, QSPR and dynamic simulation studies could give directions toward designing better anti-wear and anti-friction lubricant additives with improved properties and minimal side effects during the wearing and friction process in the chemical lubrication laboratory.

Molecular design of antioxidant lubricating oil additives via QSPR and analysis dynamic simulation method

Alternatives antioxidant lubricant additives have been proposed by many researchers to replace long-time use of multifunctional lubricant additive, Zinc-dialkyl-dithiophosphate (ZDDP). Computational methods (QSPR and MD) were successfully used to design five novel anti-oxidant lubricating oil additives with improved properties and dynamic binding energies. The five novel antioxidant lubricant additives with improved properties and without sulfated ash, phosphorus, and sulfur (SAPS) were successfully designed. These group of newly designed additives were better than other similar research from the literature and could stop or terminate complete oxidation of the lubricant. Moreover, the result of molecular dynamics simulations (MD) in which 3-(2-(3-amino-4,5-dihydroxyphenyl)-3-chloro-4-oxoazetidin-1-yl)-2-argioquinazolin-4(3H)-one with the most promised dynamic binding energy of -1487.68 kcal/mol was found to be dynamically bound better on the simulated steel coated surface than the DLC coated surface and was also revealed to be excellently good when compared with commercially sold multifunctional additives, ZDDP (197.143 kcal/mol). These groups of five newly designed additives could be easily synthesized in the wet laboratory by adding –OH and or NH2 around the ortho, meta and para position of the phenyl group of the structure template. This research will help designing new oxidation resistance lubricating oil additives with improved properties that will reduce the capacity of base oil to oxidize and form sludge during the autoxidation process of the lubricating oil.

Green oil additive g-C3N4: a feasible strategy to enhance the tribological properties of DLC film

The decrease of both friction and wear is very crucial for reducing oil consumption and the associated environmental pollution. Accordingly, the search continues for novel materials, coatings, lubricants, and systems constituted by the aforementioned ones that can potentially reduce friction and wear. In this paper, a solid–liquid composite lubrication system was constituted by combining g-C3N4 nanosheets as the lubricating oil additives with Ti-DLC film, to achieve a green lubricant providing extreme anti-wear and friction reduction functionality. Tribological properties of the composite lubrication system with different concentrations of g-C3N4 were evaluated using a ball-on-disc sliding friction tester at different normal loads. The results show that both the friction coefficient and wear rate first decreases and then increases with the increase of the g-C3N4 concentration. The lubricant with 1 wt% g-C3N4 exhibits the optimal lubricant property with the friction coefficient of 0.076, 0.078 and 0.082, reducing by nearly 24%, 20%, and 12% compared with base oil for the normal loads of 50 N, 100 N, and 200 N, respectively. However, further increase in the concentration of g-C3N4 results in significant increase in the friction and wear of the tracks. The wear rates show no marked variation with the increasing load, indicating that g-C3N4 nanosheets possess a wide load adaptation range in wear-resistance. As environmentally friendly oil additives, g-C3N4 nanosheets can effectively improve the tribological property of the composite lubrication system. Based on the characterizations of both the Ti-DLC film and wear scars by SEM, XPS, non-contact 3D surface profiler and EDS, the synergistic lubrication mechanism of the g-C3N4 nanosheets and Ti-DLC film is also proposed.

Covalent Functionalized Boron Nitride Nanosheets as Efficient Lubricant Oil Additives

AbstractHexagonal boron nitride nanosheets (h‐BNNSs) are obtained by a chemical exfoliation method from bulk h‐BN powders. The surface of h‐BNNSs is functionalized with 3‐aminopropyltriethoxysilane (APTS). Further, the amino functional groups on the surface of APTS‐modified h‐BNNSs (APTS‐BNNSs) are reacted with 4‐carboxyphenylboronic acid (CPBA) to obtain the covalently linked CPBA‐BNNSs. The morphology and structure of h‐BNNSs, APTS‐BNNSs, and CPBA‐BNNSs are comprehensively discussed. Of all the above four additives, the CPBA‐BNNSs can most outstandingly improve friction‐reducing and antiwear capacities of 150N base oil. The CPBA‐BNNSs possess excellent dispersion stability in base oil due to the phenylboronic acid groups on the surface of h‐BNNSs. Only 0.075 wt% CPBA‐BNNSs is added into the base oil, the coefficient of friction is decreased by 32.3%, and the wear scar diameter and mean wear volume of the rubbing surface are reduced by 42.9% and 88.4%. The analysis of the worn scar surface demonstrates that CPBA‐BNNSs can form a protective tribofilm containing boron and nitrogen elements on the rubbing surfaces, thereby decreasing the friction and protecting the surfaces from wear. Thus, the CPBA‐BNNSs may be recommended as a potential lubricant additive in practical applications.

Characterization and Health Risk Assessment of Exposure to Odorous Pollutants Emitted from Industrial Odor Sources

Odor pollution has a high complaint rate with strong public concern, and industrial production is an important source of this type of pollution in China. To understand odor pollution in industrial parks and to protect the safety of work environments, samples were collected from 14 industrial odor sources and then were analyzed for odorous volatile organic compounds (VOCs) and odor concentration. Based on the field data, the main compounds causing odor were assessed and identified. The cancer and non-cancer risk of odor exposure were correspondingly estimated by the health risk model. These following results were noted. ①The substances discharged from 14 sources were the same, but the content varied greatly. Alkanes and alkenes are the major odorous compounds of fibers and batteries manufacturing and in the synthesis of hydrocarbons, anhydrides, esters, and solvents. Benzene and benzene series in waste gases from refineries, purified terephthalic acid (PTA), and latex sources were the highest. Esters are the main pollutants emitted from activated carbon processing, resin synthesis, and spraying. Carbonyl compounds and sulfides are the main exhaust gases from ceramic manufacturing and additive synthesis. ②Exhaust gases from 14 sources caused strong irritation. The synthesis of lubricating oil additives and latex sources result in severe olfactory stimulation. Ethyl mercaptan, ethyl sulfide, n-butanol, and toluene were the major odorous compounds of lubricating oil additives sources. Styrene, propylbenzene, cumene, butyl acrylate, and 1,3-butadiene were the major odorous compounds of latex sources. ③The carcinogenic risk levels for 14 sources ranged from 3.06×10-7 to 1.06×10-2, expressed as life cancer risk (LCR). Refinery, PTA, ester, and latex sources had the highest carcinogenic risk among the 14 emission sources. The non-carcinogenic risk levels for the 14 sources ranged from 0.02 to 51.66, expressed as hazard index (HI). The total HI of latex synthesis, ester synthesis, petroleum refining, PTA synthesis, and fiber manufacturing has certain non-carcinogenic health risks. Factory boundaries for latex, anhydrides synthesis, and resin synthesis sources have potential carcinogenic risk.