bluuebunny/crossref_metadata_2025_split huggingface dataset:
An evaluation of antioxidants for vegetable oils at elevated temperatures
Authors: Becker R. , Knorr A. 
Published: July 2006

AbstractThe antioxidant efficacy of various oxidation inhibitors in low erucic acid rapeseed oil has been studied in a screening test at 130°C by an induction period method. Hindered monophenols, sulphides, phosphites, aromatic amines and zinc dithiophosphates yielded no or only marginal stabilising effects. Remarkably increased oxidation stabilities were observed with certain hindered bisphenols, polyhydroxybenzenes, zinc and bismuth dithiocarbamates. In high oleic sunflower oil with a lesser portion of multiple unsaturation, these additives induced relatively longer induction periods. Mixtures of zinc dithiocarbamates and 4,4′‐methylenebis‐(2, 6‐di‐tert‐butylphenol) or octylated di‐phenylamine, as well as compositions of all three compounds, exhibited synergistic effects. Under the conditions employed these additives were distinctly superior to commercially recommended formulations. A mechanistic concept of the antioxidant action of zinc dithiocarbamate is briefly discussed.
Study of deposit and friction films of overbased calcium sulphonate by PM‐IRRAS spectroscopy
Authors: Palermo T. , Giasson S. , Buffeteau T. , Desbat B. , Turlet J. M. 
Published: July 2006

AbstractThis paper deals with the study of deposit and friction films of overbased calcium sulphonate diluted in mineral oil, on metal surfaces.The technique used for this work is Infrared Reflection Absorption Spectroscopy by Fourier Transform and Polarisation Modulation (PM‐IRRAS or PM FTIR). The spectra obtained from this method contain only information on the absorption occurring in the immediate neighbourhood (⩽40 nm) of the metallic substrate and allow the average orientation for molecules adsorbed on metals to be deduced.This study shows that the adsorption of overbased calcium sulphonate on a steel surface leads to a preferential orientation of the sulphonate chains perpendicular to the surface and to a preferential orientation of the carbonate, the c axis being perpendicular to the surface. During friction, the sulphonate chains are ejected from the contact zone. We observed that the boundary film consists mainly of calcium carbonate, which crystallises into calcite.
Human health and environmental hazard characterisation of lubricating oil additives
Authors: Michael Cisson C. , Rausina Gary A. , Stonebraker Peter M. 
Published: July 2006

AbstractThe authors' company has characterised the potential human health and environmental hazards of widely used classes of lubricating oil additives and polyalphaolefin (PAO) base fluids in a battery of toxicity tests. The main classes of additives are: succinimide ashless dispersants, calcium sulphonates, calcium phenates, zinc dialkyldithiophosphates, oxidation inhibitors, and antiwear inhibitors. In summary, mammalian toxicity studies indicate that lubricant additives do not pose a significant health risk to humans. Ecotoxicity is also considered to be of low concern in general. Even though lubricant additives do not readily biodegrade, studies are under way to confirm that they are not persistent in the environment and that bioaccumulation is not a concern. Good Laboratory Practice (GLP) methods have been developed for analysis of additives involved in toxicity tests and for low concentrations (ppb) of additives in aqueous systems. Manufacturing advances are reducing the release of toxic by‐products to the environment.
On the theory of time‐dependent micro‐TEHL for a non‐Newtonian lubricant in line contacts
Authors: Yang  , Peiranm  , Shen  , Jiankun  
Published: July 2006

AbstractThis paper presents a relatively complete numerical solution to time‐dependent micro‐thermoelastohydrodynamic lubrication in line contacts subjected to constant load and entraining velocity. Sinusoidal functions are employed to model the traverse roughness on contact surfaces. The Eyring model is used to describe the non‐Newtonian flow of the lubricant. With respect to time, the problem is treated as a periodic one so that most variables, such as pressure, film thickness and temperature, can be considered as periodic functions. An efficient algorithm is developed, and a number of cases are solved. The results indicate that the lubricant squeeze induced by the motion and interaction of rough surfaces significantly affects the solution of micro‐thermoelastohydrodynamic lubrication.
A graphite intercalation compound additive in oil
Authors: Jun Tian , Qunji Xue 
Published: July 2006

AbstractA third‐stage FeCl3‐graphite intercalation compound (GIC) with flake graphite has been synthesised by a solvent method. The FeCl3 deintercalation of GIC forms thick complex film on the metal surface during the friction process, which increases the extreme pressure qualities of the paraffin liquid.
Elastohydrodynamics of the rotary lip seal
Authors: Salant Richard F. 
Published: July 2006

AbstractAn elastohydrodynamic model of the non‐leaking equilibrium behaviour of the rotary lip seal has been developed. It consists of a fluid mechanics analysis of the lubricating film, a structural analysis of the lip, an analysis of the meniscus on the air side of the seal, and an iterative computation procedure. A uniform distribution of microasperities on the lip surface is assumed. The model predicts the location of the meniscus, the film thickness and pressure distributions, and the locations of cavitation regions. It also predicts the maximum pressure that can be sealed with zero leakage, and the maximum speed above which the meniscus is ingested into the sealing zone.
Mixed lubrication — an overview
Authors: Spikes H. A. 
Published: July 2006

AbstractThe regime known as ‘mixed’ lubrication lies between those of hydrodynamic and elastohydrodynamic. This paper reviews work on this subject, in order to recognise the key areas of progress, and of ignorance. Film thickness and surface roughness are discussed, to conclude that below certain values of λ, there are limitations to earlier models. Computational solution of the micro‐EHD problem has largely succeeded, as well as more analytical approaches. The mixed lubrication regime has been studied by electrical contact resistance, friction measurement, and, more recently, analysis has been aided by optical interferometry — the implications of this work, and future prospects, are addressed.
Tribological behaviour of the adduct of bis(O,O′‐dibutyldithiophosphato)‐nickel (II) with isoquinoline
Authors: Bao‐Ling Song , Ren‐Gen Xiong , Jun‐Xiu Dong , Xiac‐Zeng You 
Published: July 2006

AbstractThe bis(isoquinoline) adduct of bis(O,O′‐dibutyldithiophos‐phato)nickel (II), Ni(dtp)2 · 2IQ, has been prepared; its crystal structure reveals that the nickel atom is bonded to four sulphur atoms of the dithiophosphate molecule, and two nitrogen atoms in the isoquinoline ring, to form a six‐coordinated complex. Evaluation of the adduct's properties as an extreme‐pressure (EP) and antiwear (AW) additive was conducted using a fourball machine. The results show that Ni(dtp)2 · 2IQ exhibits better load‐carrying capacity than Ni(dtp)2 and Zn(dtp)2, but poorer antiwear abilities. SEMs show that a wear scar surface on the ball lubricated with the adduct was much rougher than for those with isooctanol, Ni(dtp)2 and Zn(dtp)2, respectively. Further, energy dispersive X‐ray (EDX) spectra indicates that the sulphur concentration in the wear scar lubricated with the adduct is much less than that of Ni(dtp)2, which leads to a lesser wear reducing ability.
Changes in the mechanical properties of oil used in a gasoline engine
Authors: Kang Suckchoon 
Published: July 2006

AbstractThis study is concerned with the changes in and deterioration of the mechanical properties of oil used in a gasoline engine. The properties analysed were friction and antiwear performance, wear debris, load‐carrying ability and the formation of surface films.It was found that the oil run in an engine deteriorated so as to increase the wear and friction and decrease the load‐carrying ability as the running distance of oil was increased. The main cause of deterioration was related to the ability to form a protective film in the contact zone. When the film was produced by additives (sulphur), this could properly protect the surface in the contact zone undepleted from wear and friction. But as the oil deteriorated, it could not form such a film and so its protective ability on sliding surfaces diminished.
Tribological aspects of by‐pass oil filters on gasoline passenger car engines
Authors: Daniel Klaus 
Published: July 2006

AbstractContaminants in passenger car engines are physically separated from lubricating oil by full flow oil filters. The additional cleaning in by‐pass filters should allow oil drain intervals to be extended or to operate engines without oil change and reduce engine wear noticeably, as claimed by some by‐pass filter manufacturers.To establish whether the claim is mere conjecture or if the addition of by‐pass filters into the oil circuits of passenger car gasoline engines are indeed of real benefit with respect to engine and lubricant performance, a research project was initiated by the UBA on behalf of the German environment ministry.Special attention had to be paid to the influence on oil contamination, variation in viscosity, detergency, dispersancy, fuel and oil consumption, engine wear and overall reliability and durability. Some highlights of the total programme are presented in this paper.
Effect of metallic thiophosphates on dropping point and penetration properties of some greases
Authors: Mittal B. D. , Sayanna E. , Naithani K. P. , Rai M. M. , Bhatnagar A. K. 
Published: July 2006

AbstractThiophosphates of zinc and molybdenum have been used in lubricant formulations to impart extreme pressure and anti‐wear properties for some time. Zinc dialkyldithiophosphate has found favour in greases as a multifunctional ‐ antioxidant, extreme pressure and antiwear ‐ additive.
The effect of basic nitrogen compounds on the tribological performance of sulphurised olefin
Authors: Yulin Qiao , Binshi Xu , Shining Ma , Weimin Liu , Qunji Xue 
Published: July 2006

AbstractThe effect of the molecular structure of basic nitrogen compounds on the lubricating properties of sulphurised olefin has been investigated using a Timken tester. X‐ray Photoelectron Spectroscopy (XPS) and Energy Dispersive X‐ray Analysis (EDAX) were used to study the chemical states of sulphur and nitrogen on the rubbed surfaces and the reaction rates of sulphur and iron separately. It was found that the antiwear and friction reduction properties of sulphurised olefin are greatly influenced by the different molecular structures of the basic nitrogen compounds. A composite additive package containing basic nitrogen compounds with sulphurised olefin can produce either synergistic or antagonistic effects, due to the influence of the different molecular structures of the basic nitrogen compounds. XPS analysis revealed that a tribochemical protective film containing nitrogen and sulphur was formed on the rubbed surface. EDAX analysis indicated that the reaction rates between elemental sulphur and iron were influenced by the different molecular structures of the basic nitrogen compounds. It was found that the apparent reaction rates of elemental sulphur and iron are related to the tribological characteristics of the additive package.
molecular spectroscopic studies of ZDDP—PIBS interactions
Authors: Kapur G. S. , Chopra Anju , Ramakumar S. S. V. , Sarpal A. S. 
Published: July 2006

AbstractThe effect of the nature and alkyl chain length of zinc dialkyldithiophosphate (ZDDP) (R = C4 to C8) on its interactions with polyisobutenyl succinimide (PIBS) has been investigated using 31P‐NMR and infrared spectroscopy. 31P‐NMR spectra of ZDDP in the presence of PIBS showed both broad (35–850 Hz) and sharp (50–100 Hz) resonance signals due to different modes of interaction, mainly cluster formation and specific complexation, respectively. Single‐ended mono‐PIBS exhibit stronger interactions compared to the double‐ended bis‐PIBS. The proportion of sharp signals due to specific complexes in 31P‐NMR spectra of ZDDP—PIBS blends are in the order: C8 > C5 > C4+C8 > C6 = aryl ZDDP. The effect of PIBS concentration on the strength of complexes has also been studied.
Synthesis and characterisation of an effective N‐containing zinc diaryl‐dialkyldithiophosphate additive by mannich reaction
Authors: Hu X. , Yuan G. , Zhou Z. 
Published: July 2006

AbstractThis paper reports on the synthesis and tribological performance of N‐ZDDP, a type of additive containing nitrogen, that is O,O‐diaryl‐N‐methylene‐O,O‐zinc dialkyldithiophosphate, synthesised by Mannich and other reactions, and useful for improving antioxidation and anticorrosion behaviour in hydraulic, gear, and engine oils. Compared with conventional zinc dialkyldithiophosphate (ZDDP), N‐ZDDP widens the thermal decomposition temperature range, and its antioxidant behaviour is improved by 40%, and its anticorrosion properties by 50%. The load‐carrying capacity of N‐ZDDP is superior to that of ZDDP; its wear resistance, however, is similar to that of ZDDP.
Relationship between the properties of polyisobutenyl succinic anhydrides and their additive derivatives
Authors: Hancsók J. , Bartha L. , Baladincz J. , Kocsis Z. 
Published: July 2006

AbstractEngine oils today include detergency dispersancy additives to keep the engine clean, hold insolubles in dispersion, and neutralise acidic compounds.This paper describes the synthesis of a type of detergent‐dispersant based on polyisobutenyl succinimides. The type and route of synthesis influence the molecular structure, performance, and applicability of the synthesised compounds. In particular, the average molecular weight of the polyolefin chain of the intermediates used has a decisive effect. A newly developed intermediate allows the preparation of polysuccinimides with a polymeric structure.
Synthesis and tribology of aluminium hexoxylborate as an antiwear additive in lubricating oil
Authors: Hu Z. S. , Dong J. X. , Chen G. X. 
Published: July 2006

AbstractAn oil‐soluble compound containing aluminium and boron has been synthesized. The tribological properties of the compound in SN500 oil were evaluated on a four‐ball and block‐on‐ring test apparatus. The results showed that the wear resistance and load‐carrying capacity of the oil were improved, and the friction coefficient was decreased. Evidence of deposition was found in the wear scar by SEM. It is concluded that this deposition provided the oil with its good wear resistance properties.
A study of thermal and lubrication phenomena in the piston‐ring and cylinder‐sleeve tribosystem of an internal combustion engine and flash temperature calculation
Authors: Manolache Gh. , Cretu Sp. , Olaru D. N. , Bujoreanu C. G. 
Published: July 2006

AbstractThe piston ring is one of the main elements in an internal combustion engine. Together with the cylinder sleeve, the piston ring has two basic functions: (1) contacting the cylinder sleeve to prevent the gases formed above the piston from migrating to the crankcase and (2) as a translation couple, formed of the piston‐ring and cylinder‐sleeve assembly.Complex tribological phenomena occur in the piston‐ring and cylinder‐sleeve tribosystem, according to variations in sliding speed, gas pressure, and temperature.This paper presents a method of calculation of the thickness of the lubricant film in the piston‐ring and cylinder‐sleeve tribosystem, using the Reynolds equation, integrated in specific conditions. According to the Newtonian behaviour of the lubricant, the shear stresses in the lubricant film between the piston ring and cylinder sleeve are determined. A computational procedure to determine flash temperatures in the piston‐ring and cylinder‐sleeve tribosystem is presented. The theoretical results, including film thickness, sliding speed, gas pressure, and flash temperatures for a complete crankshaft cycle are also presented.
Influence of viscosity index improver, molecular weight, and base oil on thickening, shear stability, and evaporation losses of multigrade oils
Authors: Bartz Wilfried J. 
Published: July 2006

AbstractSome SAE 15W‐40 multigrade oils were formulated, using polymethacrylate (PMA) viscosity index improvers of different molecular weights, with a mixture of N 150 and N 500 as the base oil. Kinematic and dynamic viscosities, borderline pumping temperatures, pour points, shear stability, and evaporation losses were measured. The results confirm that viscometric properties as well as shear stability depend strongly on the polymer concentration and molecular weight of the VI improvers. However, evaporation losses are dominated by the volatility properties of the base oil.
The hydrocarbon/water interfacial behaviour of alkyl aryl sulphonates
Authors: Singh A. K. 
Published: July 2006

AbstractThe interfacial tension and solubilisation characteristics of the alkane/water interfaces of a series of alkyl aryl sulphonates synthesised with 1‐butanol as a co‐surfactant have been studied. It was observed that there is a narrow range of carbon numbers of these sulphonates at which maximum solubilisation of a particular alkane occurred. This range shifted progressively to a higher value, with a corresponding increase in the carbon number of the n‐alkane. The extent of solubilisation of the alkane is highly dependent on the structure of the hydrocarbon portion of the sulphonate. Unexpectedly, an ultra‐low interfacial tension seems not to be an important prerequisite for the solubilisation of hydrocarbon in the aqueous surfactant phase. The free energy decrease required for solubilisation seems to be far more dependent on the energetic interactions connected with entropy parameters. The conformational aspects of the hydrocarbon portion of sulphonate molecules, as a consequence, seem to play a decisive role in molecular interactions, leading to solubilisation of a large quantity of a particular hydrocarbon in aqueous solution of a given sulphonate. The present work aims at understanding the selection criteria for sulphonates in applications involving solubilisation and ultra‐low interfacial tension at the hydrocarbon/water interface, such as those in insecticidal/pharmaceutical formulations, fire‐resistant hydraulic fluids and enhanced oil recovery.
Performance evaluation of some organic compounds of zinc as additives for lubricating oils
Authors: Stãnescu Chiriaca , Boiangiu Victor , Dinoiu Vasile , Florescu Danilian 
Published: July 2006

AbstractSeveral organic compounds of zinc were synthesised, blended in oil, and evaluated in laboratory bench tests for AW/EP, friction, and deposition properties. Two of these, a zinc dithiophosphocarbamate and a package based on zinc dialkyldithiophosphate plus a sulphurised compound, appear to give the best overall performance.
An analytical study of the fluid film force in finite‐length journal bearings. Part I
Authors: D'Agostino V. , Guida D. , Ruggiero A. , Senatore A. 
Published: July 2006

AbstractA theoretical study has been carried out to determine an approximate analytical description of the fluid film force of a symmetrical rigid rotor supported on two finite‐length lubricated journal bearings. The analysis has been conducted assuming the Warner solution for the pressure field. The analytical approach to studying the behaviour of a system is more effective than numerical investigation, and makes it possible to cover not only an individual system, but also the whole class to which that system belongs. Furthermore, the model proposed allows quick analytical determination of the stiffness and damping coefficients.
Friction measurements of a square box deep‐drawing process
Authors: Wang Ye , He Dannong , Zhang Yongqing 
Published: July 2006

AbstractThe role of the lubricant during square box forming has been studied with a drawing lubricant performance assessment simulation system. Probes and sensors set up in different parts of the die are used to obtain the friction coefficient directly during drawing. The main finding is the validation of the relationship of the friction coefficients at the box corner, at the box side, and at the box side furthest away from the punch position. Also, a mathematical model has been set up. This model can be used to study the use of lubricant during large‐scale blank forming or to provide a new way to determine the friction boundary conditions in computer simulations.
Piston deposit control using metal‐free additives
Authors: Hamblin P. C. , Rohrbach P. 
Published: July 2006

AbstractEngines can be damaged in many ways: the principal oil‐related problems are due to deposit formation and viscosity increase. A first step in minimising the consequences of oil degradation is to reduce the formation of sludge and deposits. This can be accomplished by the judicious use of metal‐free (ashless) anti‐oxidants. Detergent/dispersant additives play a critical role in extending lubricant life by cleaning up deposits and keeping them in solution, and by neutralising acids formed during the combustion process. Several different types of antioxidants that can successfully eliminate precursors that lead to deposit formation and viscosity increase in oils in both gasoline and diesel engines have been identified. A novel, ashless, multifunctional additive that confers thermo‐oxidative stability and friction modification to engine lubricants is described here.
Friction‐reducing and antioxidant capabilities of engine oil additive systems under oxidative conditions. II. Understanding ligand exchange in a molybdenum dialkyldithiocarbamate/zinc dialkyldithiophosphate additive system in various base oils
Authors: Jensen R. K. , Korcek S. , Johnson M. D. 
Published: July 2006

AbstractThe ligand‐exchange reactions between molybdenum dialkyldithiocarbamate, Mo(dtc)2, and zinc dialkyldithiophosphate, Zn(dtp)2, have been investigated during inhibited oxidation in a model hydrocarbon (hexadecane) and in a series of Group I–IV base oils at 160°C. These investigations revealed that the ligand exchange leads to formation of single‐exchange products, Mo(dtc)(dtp) and Zn(dtp)(dtc), and double‐exchange products, Mo(dtp)2 and Zn(dtc)2, and that the extent of the exchange is significantly affected by oxidation and inhibition reactions involving the original additives, the ligand‐exchange products, the base oil, and base oil‐derived oxidation products.It is concluded that there are two reaction sequences that control the product distribution and additive consumption during oxidation in different base oils. The first sequence involves the formation of peroxy radicals and hydroperoxides, and the decomposition of hydroperoxides by Zn(dtp)2 and Zn(dtp)(dtc). One of the most important factors affecting this sequence is the base oil oxidisability. The second sequence involves inhibition of oxidation by peroxy radical‐trapping antioxidants naturally present in or added to the oil, or formed during the oxidation. Zn(dtc)2 and Zn(dtp)(dtc) appear to be very effective in this respect and are, therefore, preferentially consumed. This preferential consumption shifts the ligand‐exchange equilibrium towards the formation of Mo(dtc)(dtp) and Mo(dtp)2.The combined effect of the two sequences depends on base oil properties. The first sequence predominates in base oils exhibiting high oxidisability (e.g., in Group I oils) and the second in paraffinic oils, such as Group III and IV oils, having low oxidisability and no sulphur or aromatics. the retention of friction‐reducing capability with the Mo(dtc)2/Zn(dtp)2 additive system during oxidation appears to be tied to the first sequence, which leads to consumption of Zn (dtp)2, since the friction‐reducing capability ceases when Zn (dtp)2 is consumed and hydroperoxides can accumulate in the system. Consequently, the best retention of friction‐reducing capability is achieved in bases oils with low oxidisability.