Extreme Pressure Performance Research Articles

The Tribological Chemistry of Novel Triazine Derivatives as Additives in Synthetic Diester

Two novel triazine derivatives 2-tris(2-ethylhexyl)-3,3′,3″-(1,3,5-triazine-2,4,6-triyl)-tris(sulfanediyl)tripropanoate (TE TST) and 2-ethylhexyl-3-(4,6-dimercapto-1,3,5-triazin-2-ylthio) propanoate (EDTYP) were synthesized. Their tribological properties in synthetic diester were evaluated using a four-ball tribometer, and the thermal films and tribofilms were investigated using X-ray absorption near-edge structure (XANES) spectroscopy. The copper corrosion-inhibiting performance was explored as well. The additives can improve the extreme pressure performance of base stock. TETST displays good antiwear property and EDTYP possesses excellent friction-reducing ability. Surface analysis indicated that the thermal films are exclusively composed of FeSO4, and the tribofilms are constituted by FeS, FeS2, and FeSO4. The mechanism obtained from the XANES analysis fit well with the results of tribological tests.

A High-Performance Multifunctional Lubricant Additive for Water–Glycol Hydraulic Fluid

A water-soluble boron (B)-containing thiophosphite derivative (BTP) was synthesized, and its tribological, anticorrosion, and antirust properties as an additive for the base liquid of water–glycol hydraulic fluid were evaluated in detail. The results of tests demonstrated that BTP is indeed a high-performance and multifunctional water-soluble lubricant additive that was able to remarkably improve the extreme pressure, friction-reducing, antiwear, anticorrosion, and rust-inhibiting properties of the base liquid when added at a low adding concentration (<3 wt%). Based on a performance comparison of BTP and thiophosphite (TP), whose chemical structure is similar to that of BTP but without B, a number of primary conclusions were drawn. The B element existing as alkanolamine borate group could greatly improve the extreme pressure, antiwear, and antirust performance of BTP, especially the antirust performance, but had only a small effect on the friction-reducing and anticorrosion properties. Based on characterizations and analyses of the worn surfaces, we propose that the antiwear mechanism consists of the prepared compound BTP reacting with the steel surface during the friction process to generate a protective film mainly composed of phosphate, sulfide, sulfate, organic amine, and B2O3.

Base medium effect on the tribological behavior of oil‐water double soluble bismuth dithiophosphate

Purpose – The purpose of this paper is to understand the effect of base media on the tribological performance and tribochemistry of bismuth thiophosphate additive.Design/methodology/approach – The oil‐water double soluble additive bismuth dithiophosphate was prepared and identified. The contributions of the two base media on the additive tribological behavior and the tribofilm components were comparatively studied.Findings – The extreme pressure (EP) and friction‐reducing properties are remarkably improved with water substituted for paraffin as the base medium. The EP performance of the lubricating media containing this additive mainly results from the tribochemical reaction film on the rubbing surface, not from the viscosity of the base media. In water or paraffin medium, the adsorption process of this additive from the lubricant bulk onto the rubbing surface and the components and the properties of the tribochemical reaction films formed are different, which have important effect on the tribological per...

10.1007/s11494-008-2009-1

Antiwear and extreme-pressure properties of 3-alkyl substituted thietanes (3-butyl-and 3-hexylthietane) taken as an admixture to vaseline oil were examined. A comparison of these properties with those of dibutyl sulfide and didodecyl sulfides, as well as dibutyl and didodecyl disulfides, showed that, although 3-alkylthietanes do not exhibit wear-preventing activity, they are much superior to dialkyl sulfide and rank somewhat below the disulfides in extreme-pressure performance.

Preparation and Investigation on Extreme-pressure Performance of PyDDP Surface Modified Borate-molybdenum Agent

Using pyridinium dialkyl dithiophosphate(PyDDP) as the surface modifying agent,PyDDP surface modified nano-lanthanum borate and nano-molybdenum disulfide were prepared respectively,and borate-molybdenum agent was formed based on the two components.Infrared spectrum(IR),X-ray diffraction(XRD) and transmission electron microscope(TEM) were employed to analyze the structure of nano-particles.The results showed that borate-molybdenum agent was consisted of nano-lanthanum borate and nano-molybdenum disulfide particles,and the particle size was around 30nm to 50nm.The tribological properties of PyDDP surface modified borate-molybdenum agent were evaluated with four-ball test methods.The surface micrograph and the elements compositions for the scar of experimental ball were tested with scanning electron Microscope(SEM),electron diffraction X-ray analysis(EDXA) and X-ray photoelectron spectroscope(XPS).The results show that borate-molybdenum agent possesses better extreme-pressure properties,and the property improvement of borate-molybdenum agent is due to the formation of inorganic reaction membrane.

Investigation Factors Affecting Cutting Oil Formulations Prepared by Emulsifiers Based on Linear Alkyl Benzene and Oleic Acid‐Maleic Anhydride Esters

Seven emulsifiers based on linear alkyl benzene and five others based on oleic acid maleic anhydride esters were prepared previously (Al‐Sabagh, A.M., Maysour, N.E., Nasser, N.M., and Srour, M.R. (2006) J. Dispersion Sci. Technol., 27 (2): 239–250). The prepared emulsifier package contains four components: synthesized surfactant, oleic acid, diethanol amine, and solvents. These four components and the base paraffin oil were used in all prepared different soluble oil formulations. The different percentages of these components are incorporated to optimize the stability of emulsifier systems. The evaluation was drawn in five factors: oil stability, emulsion stability, pH, corrosion inhibition, and extreme pressure performance tests. The obtained results shows that the formulations which prepared by ABPG(4)S and ABE(9)S exhibited a good performance results. The cutting oil formulations, which based on dodecyl benzene sulfonic acid pronounced anticorrosion properties (0/0–0) comparing with the formulations, which based on maleic anhydride esters (0/1–1). The wear scar diameter performance test was carried out for all the prepared cutting oil formulations. The obtained data shows that the ABE(9)S, ABPE(4)S and SABS exhibited scar diameters; 0.71, 0.74, and 0.75 mm, respectively. Meanwhile, the scar diameter of the currently used cutting formulation exhibited 0.76 mm. This means that these formulations can be used at high extreme pressure machines.

Tribological properties of 3-alkylthietanes

Antiwear and extreme-pressure properties of 3-alkyl substituted thietanes (3-butyl-and 3-hexylthietane) taken as an admixture to vaseline oil were examined. A comparison of these properties with those of dibutyl sulfide and didodecyl sulfides, as well as dibutyl and didodecyl disulfides, showed that, although 3-alkylthietanes do not exhibit wear-preventing activity, they are much superior to dialkyl sulfide and rank somewhat below the disulfides in extreme-pressure performance.

Reactivity of alkylated phosphorothionates with steel: a tribological and surface‐analytical study

AbstractPhosphorothionates are anti‐wear lubricant additives and potential replacements for zinc dialkyldithiophosphates. In this study, ball‐on‐disc tests have been carried out combinatorially under extreme pressure (EP) conditions (100–350 MPa at 10 N load). The tests were performed in oil containing triphenyl phosphorothionates substituted with alkyl chains of different lengths. Imaging, small‐area and angle‐resolved X‐ray photoelectron spectroscopy were performed following the tribotest to probe the modification, removal and growth of the surface film. The films were composed, depending on the test conditions, of (i) iron phosphate, (ii) iron phosphates with sulphates or (iii) a mixture of iron phosphates with sulphides and sulphates. With increasing load, the dimensional wear coefficients decreased. Upon increasing temperature from 30 to 150°C, the wear became more severe. These findings suggest the formation of a tribochemical film with some EP performance, despite the severe tribological test conditions applied in this work. Copyright © 2008 John Wiley &amp; Sons, Ltd.

New water soluble EP additive for environment friendly fluids

Synthetic and semi‐synthetic fluids are known to be less sensitive to bacterial growth than soluble oils. However they often offer poor lubricating properties, especially in the extreme pressure (EP) regime. In this paper, we introduce an innovative sulfur based additive demonstrating outstanding EP performances despite being completely water soluble. In combination with oiliness and anti‐wear agents, such as phosphate esters or alkyl thio acids, it exhibits a wide range of lubricating properties which are requested for multifunctional lubricants. Finally, we show that synthetic and semi‐synthetic fluids containing this type of additive can be considered for severe metalworking operations.

Study of the tribological behavior of S-(carboxylpropyl)- N-dialkyl dithiocarbamic acid as additives in water-based fluid

There has been a growing concern for the use of water-based fluids because of the worldwide interest in environmental issues. This has promoted the research and use of water-soluble additives as environmental friendly lubricants. A kind of potential water-soluble additive, S-(carboxylpropyl)- N-dialkyl dithiocarbamic acid was prepared in this work. The friction and wear behaviors of the synthesized compounds as an additive in water-based liquid were evaluated with a four-ball tester and a ring-on-block rig. The wear scar morphology of the ball and the chemical nature of the antiwear films generated on the steel counter face were investigated with scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It was found that the synthesized additives had excellent antiwear, load-carrying and extreme pressure performance. The additive reacted with the counter-face metal and generated a surface protective film consisting of FeS, FeS 2, FeSO 4 and an absorbed compound containing N and acid.

Tribological properties of the film formed by 2-( n-Dodecyldithio)-benzothiazole as additive in liquid paraffin

The synthesis of 2-( n-Dodecyldithio)-benzothiazole is described. Their antiwear, antifriction, extreme pressure and antioxidation performance is examined in liquid paraffin. The synthesized product has been found to exhibit appreciable antiwear. The film formed by the additive during sliding process was investigated by using X-ray photoelectron spectroscopy and EPMA.

A study on colloidal PSt — a new type of water-based lubrication additive

A new type of water-based lubrication additive — colloidal polystyrene (PSt) was prepared. Transmission electron microscopy (TEM) shows that the PSt is spherical particles in submicron scale. Four-ball test results indicate that these particles can greatly improve the base fluid's anti-wear (AW) and extreme pressure (EP) performances. It was also found that the EP and AW capabilities of the fluid are not proportional to PSt content but there existed a certain value. AES examinations of the worn surfaces disclose that the surface deformed layer formed by lubricating with the fluid is half thick of that was done by the base fluid without PSt. The in situ filming is supposed to explain PSt's unique tribological behaviors.

The tribological behaviors of some rare earth complexes as lubricating additives Part 1. An investigation of the friction-reducing behaviors and an XPS study of the tribochemical characteristics

Several rare earth coordination compounds of 8-hydroxyquinoline and of di- n-hexadecyldithiophosphate were synthesized. The burnished films of these coordination compounds on a GCr15 bearing steel (SAE 52100 steel) disc were prepared. The friction-reducing behaviors of the burnished films were evaluated on a DF-PM friction tester. The friction-reducing behaviors of these complexes as additives in a lithium grease were examined on an SRV fretting wear tester. The binding energies of some typical elements in the complexes before and after friction were determined on an X-ray photoelectron spectrometer. It was found that these coordination compounds could form a quite complete burnished film on a GCr15 bearing steel surface. The lowest friction coefficient was obtained with respect to the burnished film of neodymium di- n-hexadecyldithiophosphate (NdDDP), while a decreased friction coefficient was reached with respect to the burnished film of rare earth 8-hydroxyquinolinate, as compared with the non-burnished friction pairs. Besides, the SRV fretting wear test results revealed that NdDDP in lithium grease exhibited better antiwear and extreme pressure properties than zinc di- n-butyldithiophosphate (ZDDP), while the antiwear and extreme pressure performance of rare earth 8-hydroxyquinolinates is comparable to that of ZDDP. The related results will be published in a following part of this work. The XPS results indicated that tribochemical reactions were involved in the wear process of these coordination compounds as lubricants or as lubricating additives. Here in the first part of this work, the friction-reducing behaviors of the burnished films and of the additives in a lithium grease are dealt with, while the XPS study of the tribochemical characteristics of these complexes is also reported.

Phosphosulfuration of Colloidal Calcium Carbonate—Evaluation of Antiwear and Extreme-Pressure Properties

Colloidal calcium carbonate conventionally used as detergent in lubricant, i.e., overbased calcium sulfonate, was functionalized by the product of the reaction of calcium hydroxide and tetraphosphorus decasulfide with water to yield a mineral calcium thiophosphate, or with isopropanol to yield an organic calcium dialkyl dithiophosphate. These two species are respectively comicelized with the initial calcium carbonate colloidal core. The colloidal nature of these products was confirmed and they were evaluated in a four-ball test and compared to the original nonfunctionalized colloidal additive. Both modified products exhibit improved extreme-pressure performances, while their antiwear properties compared to those of the original overbased substrate remain at least at the same level.

The tribological behaviour and tribochemical mechanism of action of oxovanadium (IV)‐dithiophosphate

AbstractVanadium (IV)‐oxo‐dicyclodithiophosphate (VDTP) was prepared and its additive properties evaluated using a four‐ball machine. The results show that VDTP exhibits better extremepressure performance, but lower antiwear activity, when compared with ZDTP. The reaction film composition, characterised by scanning Auger microscopy (SAM), X‐ray photoelectron spectroscopy (XPS) and diffractometer surface techniques, reveals that the antiwear and friction layer containing vanadium oxide, phosphate/phosphide, and sulphide, prevent the rubbing pairs from contacting directly, resulting in better extreme‐pressure and antiwear behaviour.

The antifriction behaviours of

In this paper, the antifriction behaviours of (3:1) molecules and their crystal powder were evaluated by different methods. It was found that the crystal powder possessed hexagonal close packed (hcp) crystal structure with a = 10.1 Å and c = 16.55 Å, and a transformation of crystal structure from hcp to face centred cubic (fcc) occurred easily during friction (burnishing). It was confirmed that two kinds of process, breakage of powder coagulated by nanoscale single crystals and rearrangement of the molecules along the friction direction, had occurred under the friction force. The extreme pressure (EP) performance of as an additive in paraffin liquid was investigated on an SRV oscillating wear machine. It was found that the extreme pressure load (EP value) of paraffin liquid was increased by dispersion of powder, accompanied by a slight improvement in the antifriction behaviour. it was confirmed that the improvement in EP value and antifriction behaviour of oil was dependent on the crystal structure of powder, but independent of the spherical molecular structure of or . The burnishing experimental results also proved that the antifriction behaviour was determined by the crystal structure and had no relation to the molecular structure. It was also found that fullerenes possessed some physical properties similar to those of graphite. Since the formation of compact fullerenes with high shear strength during friction can be effectively prevented by some other lubricants, it is suggested that fullerenes should be mixed with other lubricants for tribological application.

The Study of Tribological Performance and Surface Film Characterization of Bismuth Dioctyldithiocarbamate

AbstractIn this study, bismuth dioctyldithiocarbamate has been synthesized, and Its tribological behaviors, such as friction-reducing ability, antiwear property and extreme pressure performance have been respectively evaluated with a ring-on-block test rig and a fourball machine. In addition to correlate its tribological behaviors with the film formed on the metallic rubbing surface under boundary lubrication conditions, surface analyses have been conducted to characterize the surface film by means of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy(XPS) and energy dispersion of X-ray (EDX).Test results show the additive compound can effectively improve the friction and wear of the rubbing couples. On the other hand, EDX confirmed the presence of carbon, oxygen, sulfur, nitrogen, bismuth and iron on the surface; AES revealed their depth distribution of atomic concentration percentages. Whereas XPS further disclosed that the composition of the surface film was composed of organic and inorganic species including iron sulfide and sulfate, metallic bismuth, bismuth oxide and sulfide etc. which are conducive to the reduction of friction and wear.

Structure—activity correlations for sulphur EP additives

AbstractA series of new sulphur compounds was synthesised. Mercaptoheterocycles and mercaptoethanol were reacted with C12‐C22 chloroacetates. Mercaptoethanol derivatives were subsequently reacted with trialkyl borates. The solubility of S‐methylcarbalcoxy derivatives in both mineral oil and synthetic esters strongly depended on the alkyl group length, the most soluble being the C12. C14 derivatives. Three tests were used to estimate the antiwear (AW) and extreme pressure (EP) performance of the sulphur compounds: a four ball machine, an LFW‐I machine, and a Falex tester. Despite some differences resulting from the test methods, the best EP characteristics were obtained with the 2‐mercaptobenzothiazole derivatives. This showed that even a strongly bonded sulphur atom, such as that of the thiazolic ring, participates in surface layer formation. Mercaptoethanol derivatives were less soluble in either mineral or ester‐based synthetic oils. Esterification of the hydroxyl groups with trialkyl borate improved their solubility and load carrying performance.

A study of the tribological properties of some 1,3,4‐thiadiazole type lubricant additives

AbstractThe synergistic effects between the group containing S and P, hydroxyl group and a 1,3,4‐thiadiazole ring in the same molecule have been studied by investigating the tribological properties of three 1,3,4‐thiadiazole derivatives. The possibility of predicting properties of additives from their chemical structures is discussed. The results indicate that introducing a long carbon chain with a hydroxyl group (LCCWHG) into the side chains of a 1,3,4‐thiadiazole ring can effectively enhance its antiwear ability and that dimercaptothiadiazole adduct of dialkyl thiaphosphoric acid (DAODTA) can have good extreme pressure performance and excellent antiwear properties.

Testing Extreme Pressure and Anti-Wear Performance of Gear Lubricants

This paper outlines some of the problems faced by gear lubricant formulators in using standard test methods to determine the anti-wear and extreme pressure (EP) performance of their lubricants. Traditional tests for ‘load-carrying capacity’ or ‘scuffing resistance’ are reviewed and compared. A new test procedure is presented which focuses on the overall temperature performance and load-carrying capacity of the lubricant. This procedure should help in the prediction of the performance of today's advanced lubricant formulations.