Mean Wear Scar Diameter Research Articles

Impact of N,N-Bis(2-ethoxyethyl) Fatty Acid Amides on the Lubrication Performance of Kerosene Fuel F-34 for Use in CI Engines

In an attempt to avoid serious problems that can affect the efficiency of refueling ground-operated vehicles and aircraft during military operations, the Armed Forces of the North Atlantic Treaty Organization (NATO) are introducing the use of a unique fuel for both air and land use. The fuel that has been selected is the F-34, similar to Jet A-1, which is used in civil aviation, in order to replace diesel fuel in many applications. It has to be mentioned that tests performed with this fuel, which is kerosene type on the high frequency reciprocating rig (HFRR) have shown that such fuel is responsible for severe wear. This very high wear is related to the very low lubricity of aviation fuel. Having the idea to improve the lubricity of aviation fuel to the level of fuels used in compression ignition engines (diesel fuel), seven N,N-Bis(2-ethoxyethyl) fatty acid amides were formulated from various vegetable oils (sunflower oil, soybean oil, cottonseed oil, olive oil, tobacco seed oil, coconut oil, used frying oil), and they were evaluated as lubricity improvers of the aviation fuel. The required tribological measurements for lubricity rating were carried out by employing ISO 12156-1 test method on an HFRR instrument. The test conditions during the measurements were in the range of 55% to 58% for the relative humidity and 24 °C for the temperature. The results from the tribological measurements showed that all N,N-Bis(2-ethoxyethyl) fatty acid amides used were rated as efficient in order to provide an acceptable mean wear scar diameter (below 460 μm) at concentrations from 150 to 300 ppm. Additive concentrations below 150 ppm did not improve the lubricity at the required level. The increase of N,N-Bis(2-ethoxyethyl) fatty acid amides at concentrations over 300 ppm did not have any significant decrease in the wear scar diameter. A comparison between the N,N-Bis(2-ethoxyethyl) fatty acid amides showed that those formulated by non-polyunsaturated oils like olive oil and coconut oil seem to have better lubricity improver characteristics.

Experimental Investigation on the Effectiveness of Biodiesel Based Sulfur as an Additive in Ultra Low Sulfur Diesel on the Unmodified Engine

ABSTRACT Adequate lubricity and energy content play a significant role in fuel injection and performance in the diesel engine. The major challenge with ultra-low sulfur diesel (ULSD) is lower lubricity. This study aims to perform experimental analysis to investigate the wear behavior of commercial diesel with biodiesel-based sulfur (BBS) solution as an additive and examine the engine characteristics. BBS is a novel solution with higher ester and sulfur content (500 ppm). By doping this novel solution, two test fuels, BS6D1 and BS6D2 were prepared with a sulfur concentration between BS4 and BS6 commercial diesels. Compared to BS6 commercial diesel, the BS6D2 sample showed a significant reduction in mean wear scar diameter (MWSD) and coefficient of friction (COF) by 43.97% and 33%, respectively. At peak load, BS6D2 had 4.13% higher brake thermal efficiency than BS6 diesel. Due to enhanced ignition quality, the brake-specific energy consumption (BSEC) for the BS6D2 sample was found to be the lowest, i.e., 3.85% less than BS6 diesel. Furthermore, a significant reduction in exhaust pollutants for BS6D2 sample compared to BS6 diesel at maximum loads, such as smoke opacity (14.06%), unburnt hydrocarbon (8.82%), and carbon monoxide (20.45%). In conclusion, the BS6D2 sample produces the best results of all the tested fuel samples evaluated on the unmodified diesel engine.

Examination of lubricity properties of mineral base oil, containing nanoparticles of hexagonal boron nitride, and evaluation of the influence of surfactants on their sedimentation

The article presents the results of tests on the lubricity properties of SN150 base oil containing hexagonal boron nitride (h-BN) of different granulation. The boron nitride with a particle size below 100 nm and the second one with a particle size below 25 μm were used. The lubricity tests were carried out on a four-ball apparatus. The methodology of these tests was determined on the basis of the normative document PN-EN ISO 20623: 2018-02, which contains the following parameters characterising the lubricity: initial seizure load ISL [N], weld load WL [N], load-wear index LWI [N], mean wear scar diameter MWSD [mm] obtained in a long duration wear test under a specified load; wear-load curve, i.e., the dependence of the mean wear scar diameter on the load, was also performed. Tests were also carried out to check the influence of selected surfactants on the sedimentation process of hexagonal boron nitride in the SN150 mineral base oil. Based on the conducted research and their analysis, it was found that hexagonal boron nitride has a positive effect on the lubricating properties of the base oil; better results were obtained for the boron nano-nitride with a particle size below 100 nm. It was also found that the problem of sedimentation of the solid particles of hexagonal boron nitride was solved by the addition of succinimide dispersant. Keywords: tribology, lubricity, boron nitride, surfactants, sedimentation

Superior performance of ultrathin metal organic framework nanosheets for antiwear and antifriction testing

As the 2D materials were found to produce excellent performance in tribology, we have demonstrated here the use of manganese-based ultrathin metal-organic framework nanosheets [Mn-MOF (U)] as the antiwear and antifriction agent. A facile method has been developed for the synthesis of Mn-MOF (U) by hindering the 3D growth of the MOF in the presence of a strong sigma donor ligand (triethylamine) along with the bridging ligand. The atomic-level thickness (9 nm) of the Mn-MOF (U) was established by microscopic studies as well as by the Tyndall effect. The tribological parameters such as mean wear scar diameter (MWD), the average coefficient of friction (COF), and load-carrying ability of the ultrathin Mn-MOF (U) were compared with the bulk material, Mn-MOF (B). Due to atomic level thickness and 2D morphology, the performance of Mn-MOF (U) was found to be much better than the bulk material. Atomic force microscopic and scanning electron microscopic studies of the wear track indicated the exalted smoothening of the surface in the case of Mn-MOF (U), corroborating the tribological results. The upgraded activity of Mn-MOF (U) has been plausibly explained by the easy sliding of the 2D sheets compared to the bulk materials.

Tribological Analyses of Modified Jatropha Oil with hBN and Graphene Nanoparticles as An Alternative Lubricant for Machining Process

The increase of health and environmental consciousness has motivated the effort of technology improvement on lubrication by finding and exploring another potential alternative to replace mineral-based metalworking fluids. Due to this concern, vegetable-based oils have been recognised as an ideal lubricating base oil in machining due to low toxicity, biodegradable, and renewable energy sources. Moreover, nanofluids have attracted enormous attention in the field of lubrication due to excellent physical and chemical properties that can enhance tribological characterisation. The objective of the current work is to develop a new formulation of nanofluids in modified jatropha oil (MJO) by adding hexagonal boron nitride (hBN) and graphene nanoparticle additives at the lowest concentration (0.01, 0.025. and 0.05 wt. %). The physicochemical tests in terms of kinematic viscosity and viscosity index were conducted and compared with synthetic ester (SE). Tribology testing was conducted through four-ball test to determine the coefficient of friction, mean wear scar diameter, and friction torque. The result shows a significant improvement of MJO samples by adding nanoparticle additives compared to the SE. MJOg2 (MJO + 0.025 wt. % of graphene) exhibited excellent tribological behaviour by providing the lowest coefficient of friction and friction torque. Meanwhile, MJOh1 (MJO + 0.01 wt. % of hBN) provided with a smaller mean wear scar diameter among other lubricant samples. Conclusively, the addition of nanoparticle additives significantly enhanced the tribological characteristics and is highly suitable as a substitute for SE.

Evaluation of tribological characteristics of nano zirconia dispersed biodegradable canola oil methyl ester metalworking fluid

This paper focusses on the tribological characteristics of biodegradable Canola Oil Methyl Ester (COME) dispersed with various concentrations of nano-zirconium oxide i.e., ZrO2 - 0.5, 1, and 1.5 wt%. The nano particles are characterized using TEM and XRD analyses. The wear and friction properties were investigated using the four-ball tribometer and the wear and friction monitor. The worn surface and surface roughness analyses were examined using SEM/EDS and atomic force microscopes respectively. The Hastealloy pin material lubricated by COME with 0.5 wt% of ZrO2 shows significant lowering of the values of average frictional torque, mean wear scar diameter, frictional coefficient, wear, and average surface roughness in comparison with other metalworking fluids under study.

Tribological activity of ionic liquid stabilized calcium-doped ceria nanoparticles

10% Calcium-doped ceria (CCO) nanoparticles have been synthesized by sol–gel method. Their surface has been modified by surfactants, sodium dodecyl sulfate and 1-decyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl) imide to yield SCCO and IL-CCO respectively. Powder X-ray diffraction patterns of nanoparticles and surface modified nanoparticles are indicative of cubic phase of ceria. Fourier transform infrared spectra confirm the surface modification of nanoparticles, particularly with ionic liquid. Morphology of the as-prepared nanoparticles investigated by field emission scanning electron microscopy, transmission electron microscopy/high-resolution transmission electron microscopy reveals that there is decrease in size of nanoparticles from CCO followed by SCCO and then IL-CCO. Wrapping of nanoparticles by ionic liquid is apparent in the scanning electron microscopy (SEM) and transmission electron microscopic (TEM) images. The tribological activity of the well-characterized nanoparticles has been evaluated at the optimized concentration, 0.2% w/v in paraffin oil under ASTM D4172 and ASTM D5183 test conditions using a four-ball tester. Based on tribological parameters, mean wear scar diameter, average friction coefficient, load-carrying capacity, and loss of frictional power, their relative performance followed the order – IL-CCO > SCCO > CCO. Worn surface analysis by scanning electron microscopy/energy-dispersive X-ray spectroscopy, atomic force microscopy corroborated the tribological performance. The order of the activity could be correlated with the size of the nanoparticles. Moreover, lubricating properties of ionic liquid have been instrumental for the exalted activity of IL-CCO. The presence of heteroatoms of ionic liquid, nitrogen, oxygen, fluorine, sulfur along with calcium and cerium of nanoparticles in energy-dispersive X-ray (EDX) spectroscopy analysis of the wear scar surface lubricated with IL-CCO confirms the vital role of ionic liquid towards the tribological activity.

Ionic liquid stabilized Ag@C composite for improvement of triboactivity

Abstract Synthesis of carbon spheres and their composite Ag@C was accomplished by the hydrothermal method. The composite Ag@C was stabilized by the ionic liquid, 1-decyl 3-methyl imidazolium boron tetrafluoride (DMIM BF4) to yield (IL-Ag@C). The Fourier Transform Infrared(FT-IR) spectra approved the formation of composites. The powder XRD patterns of the composites matched with JCPDS files. Examination of morphological characteristics of Ag@C by scanning electron microscopy/high-resolution scanning electron microscopy(SEM/HR-SEM), transmission electron microscopy/high-resolution transmission electron microscopy(TEM/HR-TEM) revealed spherical nanoparticles of about 30–40 nm size embedded on carbon spheres of 1.2–1.6 μm. Upon addition of ionic liquid, the composite appears to be wrapped in it. Energy-dispersive X-ray(EDX) analysis associated with SEM exhibited the presence of additional elements of ionic liquid, fluorine and nitrogen, besides silver and carbon in IL-Ag@C confirming its formation. The binding energy data obtained from X-ray photoelectron spectroscopy (XPS) corroborated the formation of IL-Ag@C. Triboactivity of the carbon nanospheres and the composites were assessed in base lube PEG-200 at 0.5% w/v concentration on a four-ball tester under ASTM D4172 and ASTM D5183 conditions. Based on tribological data namely coefficient of friction(COF), mean wear scar diameter(MWD), load-carrying capacity and loss of frictional power, the relative order of activity of different additives could be established as: IL − Ag @ C > Ag @ C > IL > C spheres > PEG − 200 The above order was authenticated by morphological studies of the wear scar by SEM and AFM(Atomic Force Microscopy) techniques. The EDX analysis of the wear scar surface lubricated with IL-Ag@C showed iron also in addition to the constituent elements of the composite. Thus, active participation of the adsorbed additive towards tribofilm formation is validated. The XPS studies of the same surface, further confirm the presence of boron nitride, boron carbide along with iron oxide. These boron compounds have, indeed, enriched the tribofilm for improved triboactivity.

Wear and friction characterization of chlorella sp. microalgae oil based blended lubricant on pin on disc tribometer

In this particular research, friction as well as wear behavior for the working surfaces in contact had been carried out to examine their tendency during the use of an alternate lubrication into the mineral oil. The Chlorella sp. microalgae oil has a possible of a substitute for the mineral oil 5W-30 as well as they may be generally obtainable in considerable quantity. The test had been carried out on a pin on disc tribometer using various conditions. The modified Chlorella sp. microalgae oil combined with the mineral oil in various ratios for additional testing. According to the research carried out 10% and 20% concentration for the altered bio-oil revealed an important enhancement in terms of lowering wear rate coefficient of friction mean wear scar diameter as well as better the worn surface morphology with compare to the 5W-30 mineral oil. The optimum rise within the response parameters had been acquired with relative for their tribological analysis when the concentration for the modified Chlorella sp. algae oil improves beyond 15% and reaches 20%. Effectively, the performance of (5W-30) A10, (5W-30) A15 and (5W-30) A20 samples has a significantly better possible effect throughout the tribological analysis being a lubricant with regards to the ecological issue as well as eco-friendly.

Nanohybrid Cu@C: synthesis, characterization and application in enhancement of lubricity

ABSTRACT Carbon nanospheres, copper nanoparticles and their composite Cu@C having copper nanoparticles embedded in carbonaceous material were synthesized hydrothermally. The analytical techniques; powder X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM) with energy-dispersive X-ray spectroscopy(EDX), transmission electron microscopy/high- resolution transmission electron microscopy(TEM/HR-TEM), Raman and X-ray photoelectron spectroscopy (XPS) have been employed for their characterization. Tribological behavior of blends of the synthesized additives with paraffin oil has been investigated on a four-ball lubricant tester using ASTM D4172 and ASTM D5183 at 0.1% w/v concentration. Comparative activity of the base oil and the blends has been adjudicated considering the experimental data for mean wear scar diameter (MWD), coefficient of friction (COF), load-carrying capacity and wear rates collected from the above standard tests. The admixture-containing nanohybrid, Cu@C appears to show the best activity followed by that of copper nanoparticles and then carbon spheres. The relative activity of different admixtures is verified by atomic force microscopy(AFM) and scanning electron microscopy(SEM) with EDX results of the wear pathway. The EDX spectrum of Cu@C shows the existence of copper together with carbon on the wear scar surface confirming their contribution in the formation of in situ tribofilm. Thus, these additives may be approved for enhancing lubrication.

Development of bio-based lubricant from modified desert date oil (balanites aegyptiaca) with copper nanoparticles addition and their tribological analysis

Based on the environmental concerns related to the pollution caused by the vehicles and the demand for an alternative to the conventional lubricant resulted in the studies to be conducted that are environmental-friendly. In this study, friction and wear behavior of the surfaces in contact was conducted to observe their tendency during the application of an alternative lubricant to the mineral oil. Desert date oil was having the potential of an alternative to the mineral oil and they were available in abundant amount. During the initial stage, desert date oil was transesterified using the two-step transesterification process and further it was added to the trimethylolpropane. After this process, nanoparticles were added in different amounts to the modified desert date oil. The friction and wear behavior of the modified desert date oil was tested using four-ball tester under different conditions. For the surface topography analysis, SEM and EDS analysis were conducted. The concentration of the nanoparticles added to the biolubricant was considered based on the previous work conducted. The input parameters which were considered during the test consists of normal load, sliding speed, variation in the addition of the nanoparticles to the biolubricant (0.3–1.6% with a gap of 0.3%). Based on the study conducted, 0.9% concentration of the copper nanoparticles showed a significant improvement in term of reducing COF, wear rate, mean wear scar diameter and improved worn surface morphology was obtained with comparison to the mineral oil. The maximum increment in the properties relative to the tribological analysis was shown when the concentration of the copper nanoparticles to the modified desert date oil increases beyond 0.9% copper nanoparticles during the addition in the amount of 1.3% and 1.6%. Conclusively, the performance of the modified desert date oil with 0.9% copper nanoparticles addition has the potential impact as a lubricant with comparison to the mineral oil and other samples. The modified desert date oil with an application of 0.9% copper nanoparticles could be considered as a suitable alternative to the mineral oil while considering environmental concern and energy saving.

Tribological properties of oleylamine-modified nickel nanoparticles as lubricating oil additive

In order to improve the friction-reducing and anti-wear abilities of lubricating oil containing nickel nanoparticles as additive, nickel nanoparticles prepared by high energy ion beam evaporation (HEIBE) technique were modified by oleylamine on the surface. The morphology and microstructure of oleylamine-modified nickel nanoparticles showed that oleylamine was successfully attached to the surface of nickel nanoparticles. The friction-reducing and anti-wear properties of lubricating oil containing nickel nanoparticles and oleylamine-modified nickel nanoparticles as additive were investigated by four-ball tribometer. The addition of oleylamine-modified nickel nanoparticles into lubricating oil further reduced the friction coefficient and wear scar diameter of the steel balls lubricated by the base oil PAO6 and the engine oil CJ-4. Compared with the pure PAO6 oil, the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by PAO6 oil with the addition of nickel nanoparticles decreased by up to 32.6% and 15.3%, and that lubricated by PAO6 oil with the addition of oleylamine-modifiednickel nanoparticles decreased by up to 48.4% and 20.4%, respectively. Besides, the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by CJ-4 engine oil with the addition of 0.1 wt% of oleylamine-modified nickel nanoparticles decreased by 38.1% and 18.3% in comparison with the mean friction coefficient and the mean wear scar diameter of the steel balls lubricated by pure CJ-4 engine oil.

Mechanism of triboactivity of Schiff bases: Experimental and molecular dynamics simulations studies

Schiff bases derived from o-tolidine through its condensation with salicylaldehyde (OH-BT), naphthaldehyde (H-NT) and 2-hydroxynaphthaldehyde (OH-NT) have been synthesized and characterized by FT-IR and 1H NMR spectroscopic techniques. The synthesized Schiff bases are environmentally safe from tribological aspect as these do not contain undesirable elements like sulfur, phosphorus, and halogens which are known to affect the efficiency of catalytic converters. The triboactivity of these compounds has been studied in paraffin oil (PO) using four-ball tester (FBT) at an optimized concentration of 0.25% w/v under ASTM D4172 and D5183 test conditions. The results have been compared with that of a reference additive, zinc dialkyl dithiophosphate (ZDDP), under similar conditions. Based on tribological data, mean wear scar diameter (MWD), mean wear volume (MWV), coefficient of friction (COF), load carrying ability and wear rate, the following order has emerged for tribological behavior of the investigated additives:OH−BT>OH−NT>H−NT>ZDDP.Morphology and composition of wear scar have been studied by Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray analysis (EDX) and relate very well with the observed tribological data. The EDX analysis of the wear scar lubricated with synthesized additives provides evidence for the presence of nitrogen and oxygen. To ascertain the active involvement of the imine group towards tribological behavior, the reaction of the most active compound OH-BT was carried out with thioglycolic acid. Reduced antiwear performance of the reaction product (OH-BTS) may be directly associated with the absence of the imine group (-CH=N-). Molecular dynamics (MD) simulations have been used to study the mechanism of adsorption of the studied Schiff bases in paraffin oil on the iron slab. The order of adsorption energies of the Schiff base additive molecules has been found to agree well with the experimentally observed data. The nature of orientation or configuration of molecules after adsorption has been presented. The findings of the MD simulations have been used to propose the mechanism for tribological behavior of the investigated Schiff base molecules and product OH-BTS obtained by cyclisation of OH-BT with thioglycolic acid. The mechanism proposed from MD simulation studies points to the combined effect of heteroatoms and planarity of the additive molecule after adsorption. Accordingly, molecules with tribological properties of a high order may be formulated.

Tribological Studies of Some Quinoline Derivatives and Their Synergistic Interaction with Phosphate Ester

Antiwear properties of metal and sulfur-free synergistic formulations containing quinoline derivatives (QDs)—4-N-(7-chloroquinolin-4-yl)-1-N,1-N-diethylpentane-1,4-diamine (QD-1), 4-N-(6-methoxyquinolin-8-yl)pentane-1,4-diamine (QD-2) and 1-N,1-N-diethyl-4-N-(6-methoxy quinolin-8-yl)pentane-1,4-diamine (QD-3)—with triphenyl phosphate (PE) in polyethylene glycol (PEG) at a very low concentration, 0.25% w/v of each, have been studied on a four-ball tester using ASTM D4172 and D5183 standards. Phosphorus content in the formulations was significantly reduced compared to the frequently used antiwear additive zinc dialkyldithiophosphate (ZDDP) and it was much lower than the allowed concentration suggested by various norms. The synergistic admixtures, SQD-2 and SQD-3, significantly improved the antiwear properties of base lube compared to the ZDDP/PE/QDs alone but the behavior of SQD-1 is comparable to that of ZDDP. Minimum values of mean wear scar diameter and average coefficient of friction were found to be 0.458 mm and 0.034, respectively, for SQD-3, the admixture with the maximum antiwear efficiency. However, these values were 0.538 mm and 0.083, respectively, for ZDDP, and for base oil the values were 1.185 mm and 0.126, respectively. The load-carrying capacity was found to be much higher for the synergistic formulations than for ZDDP.Atomic force microscopy (AFM) and scanning electron microscopy (SEM) micrographs of the wear track support the tribological behavior of the above additives. The presence of nitrogen, oxygen, and phosphorus in energy-dispersive X-ray (EDX) spectra of the worn surface lubricated with SQDs indicates the adsorption of additive on the surface. The magnificent tribological behavior of SQDs may be attributed to the tribochemical film formed on the steel surface invoking phosphorus–nitrogen synergy. Quantum chemical calculations (density functional theory) for interactions of QDs with a steel surface agree well with the experimental observations.

Zinc Oxide- and Magnesium-Doped Zinc Oxide-Decorated Nanocomposites of Reduced Graphene Oxide as Friction and Wear Modifiers

Zinc oxide (ZnO) and magnesium-doped zinc oxide nanoparticles, Zn0.88Mg0.12O (ZMO), were prepared by autocombustion method. Further, nanocomposites of the as-prepared nanoparticles with microwave-synthesized reduced graphene oxide (rGO) nanosheets, ZnO-rGO and ZMO-rGO, have also been prepared with a view to see the effect of doping of magnesium in zinc oxide on the tribological properties of the nanocomposite. Morphologies of nanoparticles/nanosheets and their nanohybrids have been studied by employing scanning electron microscopy (SEM)/high-resolution (HR) SEM with energy-dispersive X-ray (EDX), transmission electron microscopy (TEM)/HR-TEM, X-ray diffraction, Fourier transform infrared, UV-visible, Raman, and X-ray photoelectron spectroscopy (XPS) techniques. Triboactivity of the additives in paraffin oil has been interpreted considering the parameters mean wear scar diameter, coefficient of friction, load-carrying capacity, and wear rates obtained from ASTM D4172 and ASTM D5183 tests using a four-ball lubricant tester at optimized concentration (0.125% w/v). The performance of base lube and its admixtures has been found to lie in the order ZMO-rGO > ZnO-rGO > ZMO > ZnO > rGO > paraffin oil. Outstanding enhancement in triboactivity of nanocomposites, particularly that of ZMO-rGO indicates that nanoparticles are irrefutably instrumental in reinforcement of rGO, and on the other hand, rGO is associated with abatement of agglomeration of the nanoparticles. Thus, interactions between rGO and nanoparticles are vehemently synergic in nature. It is noteworthy that the best results were obtained with the following optimized concentrations: ZnO/ZMO 0.25%; rGO 0.15% and composites 0.125% w/v. Morphological studies of the wear track lubricated with different additives have been performed using SEM and contact mode atomic force microscopy. Results are in conformity with the order given above. The EDX analysis of ZMO-rGO exhibits the presence of zinc and magnesium on the worn surface, supporting their role in the formation of in situ tribofilm. Their role is further corroborated by XPS studies. Owing to their excellent tribological behavior, these sulfur- and phosphorus-free composites may be recommended as potential wear and friction modifiers.

Tribological properties of nanometer Al2O3 and nanometer ZnO as additives in lithium-based grease

PurposeNanoparticles as the grease additives play an important role in anti-wear and friction-reducing property during the mechanical operation. To improve the lubrication action of grease, the tribological behavior of lithium-based greases with single (nanometer Al2O3 or nanometer ZnO) and composite additives (Al2O3–ZnO nanoparticles) were investigated in this paper.Design/methodology/approachThe morphology and microstructure of nanoparticles were characterized by means of transmission electron microscope and X-ray diffraction. Tribological properties of different nanoparticles as additives in lithium-based greases were evaluated using a universal friction and wear testing machine. In addition, the friction coefficient (COF) and wear scar diameter were analyzed. The surface morphology and element overlay of the worn steel surface were analyzed by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS), respectively.FindingsThe results show that the greases with nanometer Al2O3 or nanometer ZnO and the composite nanoparticles additives both exhibit lower COFs and wear scar diameters than those of base grease. And the grease with Al2O3–ZnO composite nanoparticles possesses much lower COF and shows much better wear resistance than greases with single additives. When the additives contents are 0.4 Wt.% Al2O3 and 0.6 Wt.% ZnO, the composite nanoparticles-based grease exhibits the lowest mean COF (0.04) and wear scar diameter (0.65 mm), which is about 160% and 28% lower than those of base grease, respectively.Originality/valueThe main innovative thought of this work lies in dealing with the grease using single or composite nanoparticles. And through a serial contrast experiments, the anti-wear and friction-reducing property with different nanoparticles additives in lithium grease are evaluated.

Investigation of the Effectiveness of Monoethanolamides as Low Sulfur Marine Fuel Lubricity Additives

In this study, six mixtures of monoethanolamides that were synthesized from various vegetable oils (Sunflower oil, Soybean Oil, Cotton Seed Oil, Olive oil, Tobacco seed oil, Used frying oil) were used as lubricating additives on a low sulfur Marine Gas Oil (MGO). All tribological measurements were carried out by using the HFRR test procedure, according to ISO 12156-1. The obtained wear results showed that all mixtures of monoethanolamides used provide satisfactory a mean wear scar diameter (WS 1.4) of less than 520 μm, at concentration levels of 80 - 140 ppm. The concentrations below 80 ppm had no effect on the fuel lubricity.

The Impact of Fatty Acid Diisopropanolamides on Marine Gas Oil Lubricity

In this study, seven mixtures of diisopropanolamides that were synthesized from various vegetable oils (sunflower oil, soybean oil, cotton seed oil, olive oil, tobacco seed oil, coconut oil, used frying oil) were used as lubricating additives in a low-sulfur marine gas oil. All tribological measurements were carried out by using the high-frequency reciprocating ring (HFRR) test procedure, according to EN ISO 12156-1. The obtained wear results showed that all mixtures of diisopropanolamides used provide satisfactory a mean wear scar diameter (WS 1.4) of less than 520 μm, at concentration levels of 60–120 ppm. The concentrations below 60 ppm had no effect on the fuel lubricity. An increase in the concentration of the diisopropanolamide mixtures led to an insignificant increase of the lubrication effectiveness.

Oleylamine-modified carbon nanoparticles as a kind of efficient lubricating additive of polyalphaolefin

The oleylamine (OA)-modified carbon nanoparticles (CPs-OA) with particle sizes of 25–35 nm were synthesized by a facile one-pot pyrolysis method. As the OA molecules were covalently attached on the surfaces of CPs-OA, the CPs-OA exhibited good dispersibility in polyalphaolefin (PAO). Then the tribological behaviors of CPs-OA as the lubricating additives of PAO were investigated in detail. Under the four-ball mode and the load of 392 N, the CPs-OA showed the best friction-reducing and antiwear properties at the optimal concentration of 1.0 wt%. Specifically, in comparison with that of pure PAO, the mean friction coefficient and mean wear scar diameter of the 1.0 wt% CPs-OA/PAO suspension reduced by 47 and 30%, respectively. The friction-reducing and antiwear capabilities of CPs-OA strengthened with increasing load from 200 to 392 N and increasing test time from 240 to 480 min. In addition, the CPs-OA-based additives could work for a long time without weakening the lubrication capability. The synergistic effect of tribofilm, including PAO molecules and the CPs-OA layer, might account for the outstanding friction-reducing and antiwear capabilities of CPs-OA-based additives under boundary lubrication.

Evaluation of Tribological Properties of Sulfur- and Phosphorous-Free Quinolinium Salts and Their Correlation with Quantum Chemical Parameters

ABSTRACTFor developing antiwear additives with high efficiency but with low sulfated ash, phosphorous, and sulfur (SAPS), N-substituted quinolinium halides, [DIP-Q]+Br− [DIP-Q=1-(3-(1,3-dioxoisoindolin-2-yl)propyl)quinolon-1-ium], [DIE-Q]+Br− [DIE-Q=1-(3-(1,3-dioxoisoindolin-2-yl)ethyl)quinolon-1-ium], [P-Q]+I− [P-Q=propylquinolon-1-ium], and [M-Q]+I− [M-Q=methylquinolon-1-ium] have been prepared and characterized by 1H- and 13C-NMR spectroscopic techniques. The tribological performance of these quinolone-based quaternary salts as antiwear additives in paraffin oil has been assessed on a four-ball test rig. The observed results have been compared with those of zinc dialkyldithiophosphate (ZDDP), a high SAPS additive. The tribotesting of these additives has been performed using 1% w/v additives concentration at different loads and times. The potential of these compounds as antiwear additives is evident from their observed tribological data: mean wear scar diameter (MWD), friction coefficient (µ), mean wear volume (MWV), and wear rates. All of the quinolinium derivatives prove to be better antiwear additives than ZDDP. Among the tested synthesized compounds, [DIP-Q]+Br− exhibits the best tribological behavior followed by [DIE-Q]+Br−, [P-Q]+I−, and [M-Q]+I−. The surface topography of worn surface studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM) shows that surface roughness is reduced to a greater extent in case of quinolinium derivatives than lubrication with ZDDP or base oil alone. Energy-dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) analysis of worn surfaces in the presence of quinolinium additives shows that the tribofilm is composed of FeBr3, Fe3O4, and organic compounds containing carbonyl and imine bonds. Theoretical investigations using quantum chemical calculations are indicative of significant chemical interactions of these quinolinium additives with metal surfaces, which is strongly supported by the observed experimental data.