Extreme Pressure Performance Research Articles

Tribological study of castor oil with surface-modified CuO nanoparticles in boundary lubrication

PurposeThe present work aims to formulate nanolubricants and improve antiwear, antifriction and extreme pressure (EP) performances of castor oil (CO) with surface-modified CuO nanoparticles as an additive in the boundary lubrication regime.Design/methodology/approachIn this study, CuO nanoparticles are modified with a surfactant sodium dodecyl sulfate (SDS) by means of a chemical method. These modified nanoparticles with varying concentrations of 0.1, 0.25, 0.5 and 1.0%w/v were used to formulate the nanolubricants. The tribological properties of non-formulated and formulated CO were examined using a four-ball tester. The tribological test results were compared with paraffin oil (PO) for similar compositions.FindingsThe nanoparticle concentrations in base oils were optimized by wear scar diameter (WSD) and load carrying capacity during antiwear and EP tests, respectively. In the antiwear test, the maximum reductions in WSD were 28.3 and 22.2 per cent; however, the coefficient of friction was reduced by 34.6 and 17.3 per cent at optimum nanoparticle concentrations in CO and PO, respectively. A significant improvement in the weld load was observed for both nanolubricants.Originality/valueThis work indicates that nanoparticle-based CO in industrial applications provides on par or better results than mineral oil. Also, it has a negligible hazardous impact on our eco-system.

The lubrication effectiveness of dialkylpentasulfide in synthetic ester and its emulsion

Abstract The application of dialkylpentasulfide (DPS) in synthetic ester (pentaerythritol tetraoleate known as PETO ester) and its emulsion is studied in this paper. PETO ester blended with DPS shows good antiwear, friction reducing and extreme pressure performance, while PETO emulsion doped with DPS exhibits only excellent extreme pressure properties. The above difference originates from the tribofilm formed on the worn surface by tribochemical reaction. SEM-EDS and XANES are applied to determine the relationship between tribochemical products and lubrication effectiveness. The tribofilm is composed of FeSO4, FeS, FeS2 and FeSO3. DPS in PETO ester and PETO emulsion undergoes tribochemical reaction dominated by sulfidation and thermal oxidation respectively, resulting in distinct tribological properties. This provides an essential explanation for the improvement of tribological properties of DPS in PETO ester and emulsion, and also indicates that sulfur is not fitted as antiwear, friction-reducing additive in water based system.

An investigation on tribological properties of the chemically capped zinc borate(ZB)/MoS2 nanocomposites in oil

The surface of self-made MoS2 nanosheets with five-layer structure was successively decorated by zinc borate (ZB) nanoparticles with coordination enhancement on the tribological performance and modified by three types of modifiers for improving dispersivity in oil. A series of characterizations determined the chemical modification and composite structure of the ZB/MoS2 nanocomposites. The tribological properties of the chemically capped ZB/MoS2 nanocomposites were extensively examined on a ball-on-ball wear tester. The average friction coefficient and average wear scar diameter of the OA-ZB/MoS2-based oil dropped by about 25.2% and 52.2%, and furthermore the extreme pressure performance increased by about 15.2% compared to oil.

Preparation and tribological properties of novel zinc borate/MoS2 nanocomposites in grease

Due to existing the synergistic effect, the novel zinc borate/MoS2 nanocomposites (ZB/MoS2) were successfully fabricated by a liquid phase-based sonication. Subsequently, they were employed as additive to investigate tribological properties in grease. The structure, composition and morphology of the ZB/MoS2 as well as ZB/MoS2-based grease were determined by a series of characterizations, such as XRD, FTIR, Raman, TEM, SEM and EDX, indicating that the ZB nanoparticles were uniformly anchored on the surface of MoS2 nanosheets. The tribological properties of ZB/MoS2 nanocomposites were extensively studied through a four-ball testing machine. The experimental results indicated that the average friction coefficient and average wear scar diameter of the ZB/MoS2-based grease decreased by about 28.2% and 23.1%, and furthermore the extreme pressure performance increased by about 23.1% comparing to base grease. Finally, the antiwear mechanism was proposed by detecting worn surface.

Oil-soluble ionic liquids as antiwear and extreme pressure additives in poly-\u03b1-olefin for steel/steel contacts

To enhance the lubricating and extreme pressure (EP) performance of base oils, two types of oil-soluble ionic liquids (ILs) with similar anion albeit dissimilar cations were synthesized. The physical properties of the prepared ILs were measured. The anticorrosion properties of ILs were assessed by conducting corrosion tests on steel discs and copper strips, which revealed the remarkable anticorrosion properties of the ILs in comparison with those of the commercial additive zinc dialkyldithiophosphate (ZDDP). The tribological properties of the two ILs as additives for poly-α-olefin-10 (PAO10) with various mass concentrations were investigated. The tribological test results indicate that these ILs as additives are capable of reducing friction and wear of sliding contacts remarkably as well as enhance the EP performance of blank PAO10. Under similar test conditions, these IL additives exhibit higher lubricating and anti-wear (AW) performances than those of ZDDP based additive package in PAO10. Subsequently, X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS) were conducted to study the lubricating mechanism of the two ILs. The results indicate that the formation of tribochemical film plays the most crucial role in enhancing the lubricating and AW behavior of the mixture lubricants.

Antiwear and extreme pressure performance of castor oil with nano-additives

The aim of the present study is to examine the antiwear, antifriction, and extreme pressure performance of castor oil with nano-additives by using a four-ball tester. CeO2 (≈90 nm) and polytetrafluroethylene (≈150 nm) nanoparticles were used as an additive in castor oil with four different concentrations in the range of 0.1–1.0% w/v. The suspension stability of the nanoparticles was improved by using sodium dodecyl sulfate as a dispersant. Different analytical tools were used to characterize the nanoparticles parameter (i.e. shape and size) as well as the worn surfaces. The additive concentration was optimized on the basis of tribological performance. The test results of antiwear and extreme pressure property have been reported on the basis of wear scar diameter and weld load, respectively. For the antiwear test, it was observed that the maximum reduction in the wear scar diameter was 37.4 and 35.3% at an optimum concentration of CeO2 and polytetrafluroethylene additive, respectively. Also, antifriction and load carrying properties of castor oil were significantly improved with the addition of nanoparticles as an additive in a small amount. The mechanism for such improvement in the tribological behavior has also been discussed.

Novel N-containing heterocyclic borate ester with hydrolytic stability as lubricant additive

A new kind of N-containing heterocyclic borate ester (MTMDB) as lubricant additive was synthesized and characterized. The tribological behaviors of MTMDB and ZDDP in 100N base oil were evaluated through four-ball machine. The surface morphology of the worn surface lubricated by MTMDB was investigated by scanning electron microscope (SEM) and the tribological mechanisms were analyzed by energy dispersive spectrometer (EDS). The results show that the synthesized additive exhibits high hydrolytic stability, good anti-wear property and excellent extreme pressure performance. When 2.5% MTMDB was added into the 100N base oil, the smallest wear scar diameter (WSD) 0.48 mm is obtained. Furthermore, S and B elements were detected on the surface of the abraded steel. This can be confirmed that MTMDB has adsorbed and reacted with the steel surface during the rubbing process and generates a protective film.

Utilization of sulphurized palm oil as cutting fluid base oil for broaching process

Broaching is one of the most severe metal cutting operation that requires the use of cutting fluids formulated with extreme pressure (EP) additives to minimize metal-to-metal contact and improve tool life. Enhancement of EP performances of the cutting fluids can be achieved by addition of sulphur containing compounds that will allow the formation of metal sulfide film that has low shear strength and good antiweld properties and acts as protection layer from wear and seizure. Most of the cutting fluids are mineral oil based. However, as regards to health and environmental issues, reseach on vegetable oil based cutting fluid have been increased recently. This paper reports a study on the sulphurization of palm oil derivatives and its usage as broaching oil. Sulphurization of the palm oil derivative was conducted via non-catalytic sulphurization using elemental sulphur at various composition and under heating of 150-160°C for 3 hr. Broaching oil was made by blending the sulphurized palm oil and additive packages. The performance parameters of the broaching oil that has been observed including load carrying capacity, wear scar diameter, corrosion protection, oxidative stability, and surface finish of workpiece. From this research, it was found that sulphurized FAME based broaching oil has excellent EP properties. The optimum formulation was obtained on composition of sulphurized FAME-mineral oil with 6% wt of sulphur. The result from the test showed that kinematic viscosity of sulphurized palm oil was about 25.3 cSt (at 40 °C), load carrying capacity was 400 kgf, and wear scar diameter was 0.407 mm. In addition, it can be concluded that the class of corrosion protection of modified palm oil was 1.b (slight tarnish category), oxidative stability at 160 °C was obtained for 0.11 hr, and the surface roughness of workpiece was about 0.0418-0.0579 μm. These performances are comparable to commercial broaching oil. By this result, it indicates that sulphurized palm oil is applicable for industrial cutting fluids formulation.

Tribological properties and action mechanism of a highly hydrolytically stable N-containing heterocyclic borate ester

Purpose The phosphorus and zinc contained in zinc dialkyl dithiophosphate (ZDDP) caused severe environment pollution and catalyst poison. Thus, the phosphorus-free additive, such as borate esters, has become one of studying hot topics in the area of oil additive. However, the stability of hydrolysis greatly limited the use of borate esters. The purpose of this paper is to improve the stability of hydrolysis by synthesizing a new kind of N-containing heterocyclic borate ester (MTTDB) as a lubricant additive. Design/methodology/approach The tribological properties of novel borate ester (MTTDB) as an additive in the base oil were studied by a four-ball machine. The element composition and chemical state of the tribofilm were investigated by scanning electron microscopy, energy dispersive spectrometer and X-ray photoelectron spectroscopy. Findings The results showed that the base oil lubricated by MTTDB exhibited high hydrolytic stability, good anti-wear property and excellent extreme pressure performance. When 2.5 per cent MTTDB was added into the 100N base oil, the smallest wear scar diameter (0.46 mm) was obtained. Furthermore, the decomposed borate ester, organic sulfide adsorbed on the worn surface was detected, and S element reacted with the steel surface and generated FeSO4, both of which contributed to the formation of the tribofilm. Originality/value Based on N-containing heterocyclic compounds, for instance, thiadiazole derivatives, introducing nitrogen and sulfur elements into borate ester, a new kind of N-containing heterocyclic borate ester (MTTDB) exhibited excellent property in hydrolysis stability, friction-reducing, anti-wear and extreme pressure. This synthesized method would be helpful for the borate ester used as additive in engine oil, gear oil and other industrial lubricants.

Improved seizure resistance of ultra-high-strength steel ironed cups with a lubricant containing SiO2 nanoparticles

Good boundary lubrication is necessary during cold stamping of high-strength steel sheets to prevent die wear and seizure of the parts owing to the high contact pressure. This study is aimed to improve the seizure resistance in a 1-step combined process of deep drawing and ironing of ultra-high-strength steel cylindrical cups using a commercial lubricant containing SiO2 nanoparticles with an uncoated die. In this study, the extreme pressure performance of the lubricant containing 0.0, 0.5, 1.0, 1.5, 2.0 and 2.5 wt% of SiO2 was first evaluated using a deep drawing process under increased blank holding forces. The optimum concentration of SiO2 was determined, i.e. 2 wt%, based on successful drawing of cups having smooth surfaces under the highest holding force. Then, the ironing limits of the cups for the lubricants containing 0 and 2 wt% of SiO2 respectively were investigated with the 1-step combined process under increased ironing ratios. The experimental results showed that seizure was observed for the lubricant containing no nanoparticles at an ironing ratio of −16.7 %. However, no seizures were observed for ironing ratios up to 4.2 % using the lubricant containing 2 wt% of SiO2. The resistance to seizure of the cup was significantly increased, leading to the formation of cylindrical cups having smooth surfaces and uniform side wall thickness.

Effects of the Nano-Diamond Additives on the Tribological Performance Improvement of Lubricating Grease

Ball screw is a very important element in precision machine industry. It has a lot of superior characteristics such as low friction coefficient, long life, high positioning accuracy and as well as converting rotational motion to linear motion. Therefore, the lubricant used in the ball screw should be low friction and wear in order to meet the aims of the above mentioned properties. The ultra-dispersed nanodiamond (UDD) is dispersed in the dispersant. The UDD is served as an extreme pressure additive in the test grease that is applied to the ball screw. Four-ball extreme pressure tests and bearing life tests were conducted in this study to evaluate the extreme pressure performance and durability enhancement of the test grease. The four-ball test results showed that the optimum selection of the dispersant category, UDD mean particle diameter and concentration added to the test grease provided by the cooperated ball screw manufacturer in this study are OLA, 200 nm and 100 ppm, respectively.

Study of soybean lecithin as multifunctional lubricating additives

Purpose – The purpose of this paper is to study the antirust, tribological performance and anti-wear (AW) mechanism of the of soybean lecithin (SL) as a kind of multifunctional lubricant additive. Design/methodology/approach – As a kind of multifunctional lubricant additive, the antirust performance of SL was tested according to ASTM D 665, and meanwhile, its tribological performances were also evaluated by Optimol SRV-I oscillating reciprocating friction and wear tester and four ball tester. The worn steel surfaces were investigated by scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Findings – The results showed that the SL exhibited excellent antirust properties in different base stock, and could effectively improve the AW and extreme pressure (EP) performances. The results of SEM and XPS indicated that a protective film was formed between steel-steel friction pair during the tribological test. Originality/value – This paper first investigated the antirust properties and the tribological mechanism of the SL as a kind of multifunctional lubricant additive, which can be very useful and will promote the application of SL in lubricant industry.

The Preparation and Tribological Property Investigation of Chrysotile Nanotubes on the Grease

The nanoMgO and active nanoSiO2 were prepared by the special liquid-phase precipitation method. Subsequently, Chrysotile nanotube was prepared of by hydrothermal method using the nanoMgO and active nanoSiO2 as precursors at 220°C under 23atm in basic solution. The surface topographies and composition of the Chrysotile nanotube were characterized by XRD and TEM. Then, the dispersive property of particles modified by oleic acid was analyzed by IR. The tribological properties) were explored by adding the modified nanomagnesium silicate hydroxide to 2# lithic-grease after dispersing uniformly. Compared with the blank sample, it can significantly reduce the friction traces of the metal surface, improve extreme pressure performance. The friction coefficient is still stable when the temperature is raised during the friction. Nanotube power can be adhered and spread on the worn metal surface. Thus self-repairing coating forms on the worn surface.

Study on the Tribological Performance of AlN Nanoparticles Additive

By using Four-ball test machine, the anti-wear and extreme pressure performances of base oil that contain aluminum nitride (AlN) nanoparticles additive was investigated. The experimental results showed that nanoparticles additive can effectively improve extreme pressure and anti-wear performance of base oil, and the optimal concentration of it in the base oil is 3 wt%. AlN and T106 compatibility experiments showed that T106 can improve extreme pressure and anti-wear performance of AlN nanoparticles additive. Two additives have synergies to improve extreme pressure and anti-wear performance of base oil.

New Metallic Detergents for Lubricating Oils

To improve anti-oxidation, anti-wear and extreme-pressure performances of metallic detergents, the over-based substrates of two detergents were modified by partial neutralization with sulfur and phosphor containing carboxylic acids. In this way, two modified detergents were prepared. The non-modified and modified detergents were evaluated by four-ball tester and thermogravimetric analyzer. The results have shown that the modification enhances anti-oxidation and extreme-pressure performance of the detergents without affecting their dispersing ability and anti-wear behavior obviously.

Investigation of oil and emulsion stability of locally prepared metalworking fluids

PurposeNo one particular fluid has cooling and lubrication properties suitable for every metalworking application. The purpose of this paper is first, to investigate the effect of anionic and nonionic mixed emulsifier system in stabilization of cutting fluid formulations and second, to study the interaction synergism of the fulfill additives of metalworking fluids to achieve low scar diameters, high stability, anti rusting and corrosion properties.Design/methodology/approachA lot of set mixtures in this work were formulated to get the demand needed for soluble oil metalworking fluids. It was based on a blend of emulsifier package (anionic‐non ionic), and in order to reach acceptable manufacturing conditions, coupling agent, stabilizer, biocide, base oil and anti‐rust additives were added to the formulation. Different percentages of these components were incorporated to optimize the stability of the emulsifier system. Standard tests were carried out to evaluate the performance of oil‐in‐water (O/W) emulsions as lubricating and cooling fluids in machining operations. The evaluation was drawn in five factors; oil stability, emulsion stability, pH, anti‐rust (corrosion inhibition), biological activity and extreme pressure performance tests.FindingsAll tests achieved excellent results according to the ASTM. From the obtained results, the formula (named EPRI 950) exhibited a good performance compared with the commercial cutting fluid.Originality/valueThis work investigates the effect of anionic and nonionic mixed emulsifier system in stabilization of cutting fluid formulations; and the interaction synergism of the fulfill additives of metalworking fluids to achieve low scar diameters, high stability, anti‐rusting and corrosion properties.

Tribological Study of Boron-Containing Soybean Lecithin as Environmentally Friendly Lubricant Additive in Synthetic Base Fluids

Environmentally friendly boron-containing soybean lecithin (BSL) was synthesised. Constant temperature and humidity box was applied to evaluate the hydrolytic stability of the novel lubricant additive. The friction-reducing, anti-wear, and extreme pressure performance of BSL in synthetic base fluids were studied by an optimol SRV-I oscillating reciprocating friction and wear tester and four-ball tester. The hydrolytic resistance test results reveal that BSL possesses good hydrolytic stability. Tribological tests show that the friction-reducing performance of BSL in A51 is inferior to PAO10. The incorporation of BSL in synthetic basestock can dramatically reduce the wear volume of the lower steel disc under different test conditions. BSL can also enhance the load-carrying capacities of the synthetic base fluids. Morphology and chemical composition of the wear surface were characterized by scanning electron microscope and X-ray photoelectron spectroscopy. The results indicated that excellent tribological performance of the BSL can be attribute to the formation of chemisorption and chemical reaction protecting films composed of Fe2O3, iron polyphosphates, organic amines, and BN, etc.

The Stannous Complex of Succinimide as Multifuctional Additive for Lubricating Oils

The excellent performance of dispersion makes poly-isobutene succinimide widely used in engine's lubricating oils. But this additive has no anti-oxidation ability, anti-friction and anti-wear behaviors. In engine’s oil, it must be used with antioxidants, extreme-pressure additives and detergents. Here the authors suggested that by metallizing the succnimide, many useful lubricating chemical properties would be affiliated to this additive. The nitrogen radicals of succinimide can combine with metal ions, such as transition metal ions, forming coordination compounds. In this article, the stannous ion was chosen as coordination ion that has stronger reducibility. The stannous chloride reacts with succinimide at 170°C, forming a new complex. The lubrication chemical experiments have shown that such complex has better performances as lubricating oil's additive, for example excellent dispersing ability, higher extreme-pressure performance, and good reducibility. All the appended abilities of poly-isobutene succinimide are ascribed to the introduction of stannous ion.

Experimental Investigation on Water Miscible Rolling Lubricant J4

A contrast test was done about the service performance of commercial emulsion II and water miscible rolling lubricant J4 with polyethylene glycol. The test results were given to have analysed them in lubrication, extreme pressure performance, simulating annealing, resistance of putrefy, rust protection etc. From the rolling mill in the lab, at the same depress ratio, the pressure reduce 3.85kN using J4 than using II, and the rolling power reduce 0.04kW using J4 than using II. By four-ball tester, the maximum load PB of J4 is 932N, the friction is 0.0518, and the wear diameter is 0.47mm. Water miscible rolling lubricant J4 is notable in lubrication, extreme pressure performance, annealing, resistance of putrefy and rust protection. The results may offer the reference for further optimization on water miscible rolling lubricant.

Tribological Performance of AlN Nanoparticles as Lubricating Oil Additive

By using Four-ball test machine, the anti-wear and extreme pressure performance of the lubricating oil that contain the ceramics nanoparticles additives were investigated. With the help of scanning electron microscopy (SEM), the worn surface is observed, and its tribological performance is studied. The experimental results show that nanoparticles additives can effectively improve extreme pressure and anti-wear performance of the lubricating oil, and the optimal concentration of it in the base oil is 3 wt%. With ZDDP additive contrast experiment show that under low-load and long time conditions, ZDDP additive is far inferior to nanoparticles additives, and containing AlN nanoparticles additives lubricating oil mainly happen Fatigue wear and scratch.