bluuebunny/crossref_metadata_2025 huggingface dataset:
Improvement of silahydrocarbon performance with additives
Authors: Thomas S. G. , Campbell D. G. , Hsu C. J.
Published: July 2006

In order for silahydrocarbons to qualify, for use in a broad range of applications (automotive, aerospace, and industrial), the formulated fluid must have good oxidative stability and lubricity.

This paper compares the response of a silahydrocarbon, a synthetic hydrocarbon, and a mineral oil to various antiwear and antioxidant additives. A merit rating system is described: it provides a relative ranking of the different formulated fluids according to performance.
Rheological and tribological characterisation of six wet lubricants for space
Authors: Sicre J. , Berthier Y. , Flamand L. , Reynaud P. , Vergne P. , Godet M.
Published: July 2006

Dry lubricants are often used in space because of their excellent behaviour in a vacuum and their thermal stability. However, mechanisms which are heavily loaded, with a high sliding rate, a long life span, or needing a stable friction coefficient cannot use this kind of product. They can be replaced by wet lubricants specially developed for vacuum applications. Such lubricants have a low vapour pressure in order to minimise outgassing losses and avoid contamination.

Since European experience in the field of wet lubrication in space is rather limited, the French Space Agency CNES, with the help of the LMC (Laboratoire de Mécanique des Contacts ‐ Contact Mechanics Laboratory), is currently characterising several wet lubricants for use in space applications.

The selected lubricants were tested on a vacuum friction test bench which allows the main contact parameters to be controlled: speed, load, and kinematics. The bench is equipped with vacuum facilities and, since it runs under air, neutral gas, or vacuum, it can be used to study the effects of atmosphere. Variations of physical properties (viscosity) versus temperature (−60°C to 100°) and pressure (from atmospheric pressure to 500 MPa) were studied for all the lubricants tested, and these characteristics take into account in the analysis of the tribological test results.

This paper briefly lists the characteristics of a space environment (vacuum, microgravity, etc.) and their consequences for lubrication. It describes the equipment used and the tribological and rheological test results obtained on six wet lubricants (three oils and three greases). It also contains conclusions in terms of recommendations about the use of such lubricants.
Structure–property relationships of model chlorstrifluoroethylene oligomer compounds: Thermal stability
Authors: Snyder Carl E. , Gschwender Lois J. , Fultz George W. , Paciorek Kazimiera R. L. , Kratzer Reinhold
Published: July 2006

Low molecular weight chlorotrifluoroethylene (CTFE) oligomers have been the base fluid for an extensive DoD research and development programme for nonflammable hydraulic fluids, compatible elastomeric seals, components, and systems. To gain a more fundamental understanding of the effect of the specific isomers and other components of commercial CTFE fluids on the important fluid properties, model compounds were synthesised and their physical and chemical properties were determined. Thermal stability, in the presence of typical hardware system metals, is one of the more important properties and is discussed in relation to molecular structure. Two Microscale evaluation techniques were devised and validated. Optimum thermal stability is observed when the chlorines in the molecules are positioned as far apart as possible. In general, it was found that the compounds with larger amounts of chlorine were less stable and the positioning of the chlorine in the molecule had a lesser, but measurable effect.
The tribological study of S‐(1H‐Benzotriazol‐1‐yl) methyl N,N‐dialkyldithiocarbamates as additives in synthetic lubricants
Authors: Ren Tianhui , Xue Qunji , Wang Hanqing
Published: July 2006

The load‐carrying capacity, wear, and friction properties of four S‐(1 H‐Benzotriazol‐1‐yl)methyl N,N‐dialkyldithiocarbamates added to a synthetic lubricant (diester) were evaluated using a four‐ball test machine and an Optimal SRV tester. The results indicate that these compounds added to the diester possess good load‐carrying capacities and antiwear properties. The rubbed surfaces were investigated using X‐ray photoelectron spectroscopy (XPS) analysis and the antiwear mechanism is discussed.
Oils with low environmental impact for modern combustion engines
Authors: Mattei L. , Pacor P. , Piccone A.
Published: July 2006

Experimental work was carried out to evaluate the influence of synthetic lubricants on engine performances and their consequences for the environment. The effect of the rheological and compositional characteristics of lubricants on fuel efficiency, oil consumption, thermo‐oxidative stability, and wear was investigated. To this purpose, both conventional tests normally used for assessing oil quality according to European specifications and non‐conventional/in house tests were used. Among the latter, engine oil consumption, minimum oil film thickness, bearing wear, valve train wear, thermo‐oxidative stability, and high temperature deposit tests were included.

Preliminary conclusions show that a 5W‐30full synthetic oil has a lower impact on the environment than a current IOW‐40 part synthetic‘European’oil and is a better compromise between fuel efficiency and oil consumption.

A field test programme is in progress in order to assess general engine performance, especially oil consumption and the effect of oil on catalyst efficiency.
The origins of synthetic lubricants: The work of Hermann Zorn in Germany part 1 basic studies of lubricants and the polymerisation of olefins
Authors: Jantzen Eilhard
Published: July 2006

This paper has been written to commemorate this January the 100th anniversary of the birth of Hermann Zorn, whose research led at the beginning of the 1930s to the first synthetic oils being produced in Germany. This development work, started in 1926 and pursued up until 1944, can be seen to have taken place in four successive stages:

basic research and synthesis of hydrocarbons in pursuit of an‘ideal’lubricant,

work to develop synthetic lubricants on the basis of olefins,

research on and development of additives to improve the performance of synthetic lubricants,

synthesis, research into structure, and process development of esters for special lubricants with advanced oxidative stability and good low‐temperature behaviour.

The first part of this survey of his work describes his basic research on lubricants and his work on the polymerisation of olefins. The second part will look at his work on additives and ester oils and their application in aviation.
The wear behaviour of polymer composite gears
Authors: Mao K. , Hooke C. J. , Walton D.
Published: July 2006

In order to examine the wear of polymer composite gears, a test facility has been developed which has enabled the wear of gear trains to be measured continuously during gear operation. Brief details of the method are given. The purpose of this paper is to report some of the results obtained from this facility and, in particular, to discuss the effect of temperature on the wear of acetal gears.
Self‐diffusion of oil in lubricating greases by NMR
Authors: Hermansson Mathias , Johansson Erik , Jansson Mikael
Published: July 2006

Self‐diffusion of base oil in six model lubricating greases and in the base oils themselves was measured using pulsed‐field gradient nucleic magnetic resonance (NMR) at 23, 40, 70, and 90°C. Three of the greases were based on naphthenic mineral oils, and three were based on synthetic polyalphaolefin oils. Soaps of 12‐hydroxy stearic acid were used as thickener agents in all six greases. The purpose of the investigation using NMR was to see if structure varies with temperature, and if NMR is a viable method for structure determination.

The ratio between the diffusion coefficient of the base oil in the grease and the neat base oil in itself was evaluated as a function of temperature. This ratio was taken as a direct indicator of the obstruction effect that the thickener has on the oil.

The thickener showed a stronger obstruction effect on the base oil in the synthetic grease than in the mineral‐based grease. This was related to the soap content, which, for these greases, is roughly twice as high in the synthetic greases as in the mineral ones. The obstruction effect was constant in the temperature range 40–90°C for mineral‐ as well as synthetic‐based greases. NMR was judged to be a promising method for investigating how the gellant affects the diffusion coefficient of oil in a lubricating grease.
An evaluation of the influence of cylinder liner finish and synthetic lubricating oil on exhaust hydrocarbon species from an SI engine
Authors: Willcock M. , Tidmarsh D. H. , Foss P.
Published: July 2006

As part of the continuing attempt to reduce emissions from automotive engines this paper investigates the effect of cylinder lubrication on hydrocarbon emissions, and shows that the effect of a synthetic oil on total emissions is insignificant. However, more positive results have been obtained using cylinder surface finish to control oil layers in the combustion chamber. Studies of the hydrocarbon species in the emissions showed significant differences due to surface finish profiles.
Modified TMP esters as multifunctional additives in metalworking fluids
Authors: Mathiesen T.
Published: July 2006

This paper looks at newly developed trimethylolpropane (TMP) esters, which have multifunctional properties as additives in aqueous metalworking fluids. Such TMP esters can replace the previous monofunctional esters, which provided only lubrication.

New TMP esters are obtained by chemical modification of traditional TMP esters, and provide the functions of lubrication, corrosion protection, and co‐emulsification in one product. The paper looks at the chemistry of these esters, and their properties. Some experimental products are also examined.
Synthetics versus vegetable oils: Applications, options, and performance
Authors: Miles P.
Published: July 2006

Environmental concerns have brought forward vegetable oils as alternatives to more expensive synthetic lubricant base stocks, in moderate operating conditions. The contents of various acids, such as oleic and linoleum, can be changed by selective breeding to produce more desirable lubricating properties and less oxidation vulnerability.

Different tests are needed for such lubricants, and the Baader test has been modified to show the ageing stability of rapeseed oil raffinate, TMP trioleate, dioctyl adipate, and HOSO. Such oils can also be modified with additive packages.
Assessment of ep additives for water‐miscible metalworking fluids
Authors: Mandakovic R.
Published: July 2006

This paper presents a short overview of the background to EP additives and their operating mechanism in relation to temperature activation, in the formulation of water‐miscible metal working fluids.

The physical and chemical properties, determined using standard laboratory equipment, and dynamic tests, of different formulations of water‐miscible metal working fluids are given. The main work reported here was to compare the EP performance of available commercial additives, looking particularly at commercial variations of phosphate esters as replacements for chlorparaffins. The paper concludes that the ‘tapping and drilling’ test, which is a relatively good simulation of practical conditions in metalworking operations, can be successfully used as a way of selecting the appropriate EP additives, and for formulation of the concentrate.
A study of the role of solid lubricant and fibrous reinforcement in modifying the wear performance of polyethersulphone
Authors: Bijwe J. , Rajesh J. John , Jeyakumar A. , Ghosh A. K.
Published: July 2006

High‐temperature polymers are generally preferred for those tribology applications where cost is secondary and performance is the primary consideration. Since frictional heat dissipation limits the usefulness of polymers because of their poor thermal conductivity, high‐temperature polymers are preferred in applications which have harsh operating conditions. In this paper, a high‐temperature polymer, polyethersulphone (PES), was selected for some adhesive wear studies, along with two PES composites containing 18% glass‐fibre (GF) reinforcement and two solid lubricants, i.e., PTFE and MoS2 (2% each). Adhesive wear studies of these materials on two pin‐on‐disc machines indicated that neat PES was not a good tribo‐material. However, incorporation of GF and solid lubricants enhanced the wear performance by an order of two. PTFE was found to behave better than MoS2. However, after long sliding duration both the lubricants performed almost equally well. The topography of the surface of the pins and the disc was studied using SEM to investigate the wear mechanisms.
Preliminary studies of the influence of cryo‐treatment on the mechanical and tribological properties of ptfe and composites
Authors: Indumathi J. , Bijwe Jayashree , Ghosh A. K.
Published: July 2006

Cryogenic treatment of polytetrafluoroethylene (PTFE) has proved beneficial in improving the abrasive wear resistance of several polymers, and it was thus assessed in an adhesive wear mode, as well. Preliminary investigations on the effect of cryogenic treatment on the tribological properties, in adhesive wear mode, and mechanical properties of neat PTFE and it composites filled with bronze or short glass fibres (GF) were carried out. It was found that, although the improvement in the wear and friction performance of neat PTFE and a GF + PTFE composite was significant, no such positive effect was observed for the bronze + PTFE composite. On the contrary, this composite showed a deterioration in performance.

The reason behind the improvement in the tribological behaviour of neat PTFE and the GF + PTFE composite could not be clearly understood. However, it was confirmed that, if the treatment adversely affected the mechanical properties, then the tribological performance also deteriorated. An examination of the worn surface of the material and the counterface disc using a scanning electron microscope revealed changes in the microstructure due to the treatment. It was also confirmed from these SEM studies that the compatibility of bronze and PTFE was very poor, which led to poor performance of the composite both in the untreated and the cryo‐treated form. Further detailed investigation and analysis of various materials and composites, however, are necessary to establish the utility of this technique.
Viscosity–pressure–temperature behaviour of mineral and synthetic oils
Authors: Gold P. W. , Schmidt A. , Dicke H. , Loos J. , Assmann C.
Published: July 2006

A new high‐pressure viscometer that can measure viscosity at pressures up to 0.8 GPa has been developed in the authors' laboratory. The ‘modulus equation’ has been used to compare the behaviour of mineral and synthetic lubricants. Among the oils investigated there was one ester that biodegraded rapidly both before and after ageing in a long‐term test‐rig operation. To facilitate a comparison or application of the results to other oils, an analysis of the correlation between the viscosity—pressure coefficient and the kinematic viscosity measured at atmospheric pressure has been provided. A prediction of lubricant film thickness based on high‐pressure viscosity data is compared with film thickness measurements in a roller bearing.
A tribological study of an S–P–N containing additive in polyalphaolefin
Authors: Li Jiusheng , Ren Tianhui , Wang Dapu , Liu Weimin , Xue Qunji
Published: July 2006

The load‐carrying capacity, antiwear, and friction reduction properties of a novel S—P—N additive (BMDDP) added to a synthetic lubricant, polyalphaolefin (PAO), were evaluated using a four‐ball test machine. The results were compared with those of a commercial S—P—N additive (T307), and show that BMDDP is an excellent extreme pressure and antiwear additive in polyalphaolefin, similar to T307. The rubbed surfaces were investigated using X‐ray photoelectron spectroscopy, and the antiwear mechanism is discussed.
Lubricating oils based on chemically modified vegetable oils
Authors: Bírová A. , Pavlovičová A. , Cvenroš J.
Published: July 2006

Vegetable oils are a type of easily biodegradable ester‐type lubricant derived from renewable resources. Their importance, from the environmental view‐point, is evident, especially in loss lubrication, hydraulic systems with increased risk of damage, etc. They are characterised by good lubricity and good anticorrosion and temprature‐viscosity properties. Some disadvantages, particularly low thermal oxidation stability and poor cold flow behaviour, can be mitigated by structural modifications. In this study, possible substitutions of the alcohal part of triacylglycerols as well as changes in acyl unsaturated chains are discussed. Attention is paid particularly to the epoxidising of double bonds in acyls resulting in the formation of oxirane rings. By opening these in the presence of hydrogen donors, it is possible to obtain new derivatives and polyfunctional compounds that are acceptable as environmentally friendly lubricants.
Benefits of synthetic lubricants in industrial applications
Authors: Murphy W. R. , Blain D. A. , Galiano‐Roth A. S. , Galvin P. A.
Published: July 2006

Synthetic lubricants were originally developed and used for applications where petroleum products were inadequate (e.g., at extremely high and low temperatures, under extreme wear conditions) or where special characteristics, such as long life, improved equipment efficiency, or non‐flammability, were needed. However, the use of synthetic lubricants is not restricted to special applications, but is also useful when they can provide cost efficiency in areas such as machine reliability, oil life, energy consumption, biodegradability, and safety. Among many successful applications, typical cases where synthetic fluids have clear advantages over conventional lubricants include: high‐temperature lubricants for plastic calenders (significant lengthening of oil‐change intervals, fewer machine shutdowns): worm gear drives under severe service conditions (increase in efficiency, lower operating temperatures); air compressors (elimination of combustible petroleum residues); hydraulic fluid in fire‐resistant applications (mining equipment, pressure casting machines, steam turbine control systems); and high‐speed greased bearings (reduced friction losses).

The benefits of synthetic lubricant base stocks are derived not only from their basic molecular structures but also from the absence of harmful molecular species often unavoidably present in conventional mineral oils in small, but significant, concentrations. There are very many compounds in crude oil, and while many, or most, of the harmful ones are removed or upgraded by refining, depending on the methods used, a significant number will inevitably remain in lubricating oil stocks, whether solvent‐ or hydrotreated. Thus, conventional oils comprise a wide variety of molecular species, many of which are not well characterised. In contrast, synthetic products normally are produced by chemical reactions of very pure, small molecules in which pressure, tempesutuse, und the ratio of reactants cun he curefully controlled. Frequently, the synthesis o j the reaction up to the desised end product includes severul steps, each of which necessitutes a pusifcution of the intermediute psoducts. It is this resulting ji‐eedom jhom undesisuhle compounds that gives synthetic lubricants their distinctiiie characteristics. It also contrihutes to their higher cost, compased to mineral oils, the oiserall cost of u synthetic product being the sum of the costs of the raw materials und the costs of the individual reuction steps.

It is estimuted thut approximutely 80% of the worldwide synthetic luhsicants market is repsesented by three generic groups: polyulphaolejins (∼45%), organic esteia (∼25%), and polyglycols (∼10%). Of the remaining synthetic luhricunts, phosphate esters and polyhirtenes make up probably the largest sules volumes, with about S% each in total. This paper. provides an overview of the types, characteristics, uses, und udwrztages of synthetic lubricants, based on these major technology categories.
Recent trends in environmentally friendly lubricants
Authors: Hörner Dietrich
Published: July 2006

Many of the lubricants used in the world today cause environmental pollution through total‐loss applications, spillage, evaporation, and in other ways. To reduce this environmental damage, new lubricants that are rapidly biodegradable and ecologically non‐toxic have started to be developed and marketed. This paper discusses the introduction of environmentally friendly lubricants and their constituents, with particular emphasis on their environmental benefits, applications, the limits to their use, their technical performance characteristics, and relative cost aspects; many of these lubricants are based on vegetable oils and esters. Comparisons are also made in the paper with conventional mineral‐oil based materials.
A study of the tribological behaviour of dialkyldithiophosphate esters as additives in rape seed oil
Authors: Li Jiusheng , Zhang Yanyan , Ren Tianhui , Liu Weimin , Wang Dapu
Published: July 2006

Zinc dialkyldithiophosphates (ZDDP) cannot be used as additives in biodegradable lubricants because of their zinc content. In investigating substitutes for ZDDP, dialkyldithiophosphate esters have been synthesised, and their tribological behaviour as additives in rape seed oil has been evaluated using a four‐ball friction and wear tester and compared with that of ZDDP. The results show that these additives have better antiwear properties and load‐carrying capacity than rape seed oil alone. The morphologies and the elemental chemical states on the worn surfaces of the lubricated steel balls of the tester were examined using X‐ray photoelectron spectroscopy and scanning electron microscopy. The tribological mechanism is discussed on the basis of the experimental results.
The friction and wear of different polymers under high‐load conditions
Authors: De Baets P. , Ost W. , Samyn P. , Schoukens G. , Van Parys F.
Published: July 2006

Engineering polymers are increasingly being used as self‐lubricating materials in demanding high‐load applications. In this study, a comparison has been made of the tribological behaviour under high‐load conditions of two grades of polyamide and polyethylene terephthalate as well as polyacetal. Large‐scale testing is used to reduce edge effects. It has been found that the two grades of polyamide and pure polyethylene terephthalate are prone to stick—slip, while internally lubricated polyethylene terephthalate and polyacetal show low friction and wear and no stick—slip.
Synthesis and tribological behaviour of phosphorus—nitrogen‐modified rape seed oils as biodegradable lubricant additives
Authors: Jian‐hua Fang , Bo‐shui Chen , Bin Zhang , Wei‐jiu Huang
Published: July 2006

Two types of phosphorus—nitrogen‐modified rape seed oils as biodegradable lubricant additives were synthesised and characterised by infrared spectroscopy. Their tribological properties in rape seed oil and in mineral oil were evaluated in a four‐ball tester. The morphologies of the worn surfaces were analysed by scanning electron microscopy. The results show that the modified rape seed oil additives improve the load‐carrying capacity and the antiwear and friction‐reducing properties of rape seed oil more than they do those of mineral oil. The inferred mechanism of lubrication is that a high‐strength adsorption film and/or tribochemical reaction film forms on the rubbing surfaces, due to the carrier effect of long‐chain rape seed oil molecules and to the high reaction activities of phosphorus and nitrogen and their synergism.
Total vegetable‐oil based greases prepared from castor oil
Authors: Dwivedi M. C. , Sapre Smita
Published: July 2006

Total vegetable oil greases are those in which both the lubricant and gellant are formed from vegetable oil. Vegetable oil may be used as a lubricant as such or, with appropriate structural modification, as an ester or alkylated ester. Total vegetable oil greases have the advantage of good biodegradability and conform to the requirements for high performance.

Total vegetable‐oil based greases can be formed by mixing preformed soap and lubricant in the required proportions to form a grease with the desired properties. Alternatively, a grease can be formed from the same vegetable oil by simultaneous alcoholysis and saponification of the oil to form the lubricant and soap. The alkali used as a catalyst for the alcoholysis reaction serves as a reactant for the saponification reaction. The use of the appropriate proportion of oil, alcohol, and alkali will thus form a grease of the desired composition.

A simultaneous reaction scheme to form sodium and lithium grease using castor oil has been studied. The alcoholysis reaction is separately studied for its kinetics, and the kinetics of the alcoholysis and saponification reaction are reported. Greases with 20% soap have been formed and their properties evaluated.
Performance of synthetic oils in the hydrodynamic regime ‐ II. Generalisation
Authors: Glavatskih Sergei B. , Larsson Roland
Published: July 2006

In Parti I the results of an extensive experimental investigation of the performance of environmentally adapted oils in the hydrodynamic regime were reported. Four oils were tested in a tilting‐pad thrust bearing for different combinations of load, shaft speed, and supply oil temperature. In this second part, details of a generalisation procedure are described. A number of parameters representing the physical properties of an oil, such as viscosity and viscosity‐temperature coefficient, are adopted. The influence of each of these parameters on minimum oil film thickness, maximum temperature rise, and bearing power loss is then analysed. It is shown that viscosity measured at the supply oil temperature is the most important parameter. The effects of the viscosity‐temperature coefficient and oil thermal conductivity are less pronounced and yet significant. It is also shown that it is not possible to select an optimum oil that yields maximised oil film thickness, minimised temperature rise, and minimised power loss at the same time.
Properties and applications of synthetic greases
Authors: Kimura Hiroshi , Onuki Yuji
Published: July 2006

Mineral oils are still predominant as base oils for lubricating greases, although increased numbers of greases have been developed with synthetic oils because of their good performance properties, including thermal/oxidation stability, low‐temperature fluidity, and plastics compatibility. Long life under high‐temperature conditions and good low‐temperature fluidity are required of greases used in bearings of engine electrical components. As many plastics are used in place of metals for the purpose of weight saving, synthetic hydrocarbon greases are used that do not have adverse effects on plastics. Various other special synthetic greases are also in use depending on specific requirements, such as conductivity and vacuum conditions. The properties and applications of various synthetic greases are discussed here.
The influence of engine oil on diesel exhaust emissions
Authors: Gligorijevic R. , Jevtic J. , Biresaw G.
Published: July 2006

Increasingly stringent emission legislation, together with the requirements for improved diesel engine performance, such as fuel economy, friction reduction, and extended drain intervals, have led to attention being focused on engine oil quality. The use of low‐friction engine oils can improve engine fuel efficiency and lead to a significant reduction of gaseous emissions. Therefore, engine oil is of importance when considering engine design parameters.

This paper describes a study of the contribution of engine oil to diesel exhaust emissions. The investigations have shown that diesel engine particulate emissions as well as hydrocarbons and NOX emissions depend on the lubricant oil properties, in particular on the sulphur content, volatility, and metal content.
Synthetic polyurea extreme‐pressure greases
Authors: Singh T. , Bhan A. K.
Published: July 2006

This paper describes the preparation of synthetic polyurea greases and evaluates their performance. The polyurea greases were prepared in situ by reacting diisocyanate with monoamines and ethylene diamine in the presence of a synthetic base oil (polyalphaolefin). Two different extreme‐pressure (EP) additives blended with the prepared polyurea greases were evaluated for their EP activity in four‐ball and Timken tests. The additivated greases gave higher loads, and higher values of weld load in the four‐ball test as compared to the polyurea grease without additive. The blended greases were also found to pass rust, corrosion, oxidative stability, and shear stability tests. The topography of the wear‐scar surfaces was investigated using scanning electron microscopy.
Suitability of vegetable oils as industrial lubricants
Authors: Gerbig Y. , Ahmed S. I. ‐U. , Gerbig F. A. , Haefke H.
Published: July 2006

This paper reports on the application‐relevant properties of sixteen commercially available vegetable oils tested without additives in accordance with established standards. Their performance was compared with each other and with that of mineral oil and synthetic esters. The basic characteristics of all the oils (density, viscosity, pour point, cloud point, flash point and fire point) were initially determined. A chemical analysis of the vegetable oils was carried out to determine the acid value, saponification and iodine numbers. Additionally, the oxidative stability of all the oils was tested. The tribological performance, lubrication, and wear protection of the oils were judged under abrasive as well as adhesive conditions. The comparative study of the test vegetable oils showed great differences in the properties of the oils. All the vegetable oils tested revealed weak points during testing, including rape seed and castor oils, which have established uses in industry. This study shows that certain vegetable oils, such as sesame oil and wheatgerm oil, may have potential for use in selected technical applications. The mineral oil and synthetic esters showed markedly superior performance when tested under adhesive conditions, but comparable behaviour to the other oils under abrasive conditions.
Interaction between zinc dialkyldithiophosphate and amine
Authors: Shiomi M. , Tokashiki M. , Tomizawa H. , Kuribayashi T.
Published: July 2006

This paper reports work on complex formation from ZDP and various aliphatic amines, and their equilibrium states in oil, adsorptivities and antiwear properties are investigated. Complex formation from ZDP and amine was proven by isolation and identification of solid crystals, and various complexes were found from mono‐ and diamines. The complex from monoamine has lower adsorptivity than free ZDP, while the poorer adsorptivity of ZDP/monoamine complex makes its antiwear property worse.
Raman microspectroscopy of a working elastohydrodynamic contact
Authors: Gardiner Derek J. , Baird Ewan M. , Craggs Carolyn , Dare‐Edwards Martin P. , Bell John C.
Published: July 2006

The design and operation of two closely‐related pieces of apparatus which allow the acquisition of Raman spectra from lubricant fluids ‘in lubro’ in an elastohydrodynamic contact are reported. Spectroscopic sensitivity was not sufficient to allow a detailed structural interpretation of the spectra under these extreme conditions. However, the systems have been used in a novel way to obtain profiles and maps of the pressure distribution, as experienced by the fluid in the working elastohydrodynamic contact.
Numerical calculations of the pressure spike in elastohydrodynamic lubrication
Authors: Venner C. H. , Napel W. E. Ten
Published: July 2006

The application of advanced multilevel techniques to the solution of the EHL line contact problem has resulted in a multilevel solver of complexity O(n In n). The reduction in computing time thus obtained enables the use of large numbers of nodes and allows detailed study of the pressure spike. Both occurrence and height of the spike as a function of the governing parameters were studied. The parameter range where a pressure spike can be expected, and the results of spike height calculations, are presented.
Effects of NOx on liquid phase oxidation and inhibition at elevated temperatures
Authors: Johnson M. D. , Korcek S.
Published: July 2006

Nitrogen oxides (NOx =NO2 +NO) play a role in degradation of lubricating oils in internal combustion engines. Interactions of NOx with fuel derived species have been shown to lead to varnish and deposit formation. Mechanisms of interactions of NOx with additive and base oil components have not, however, been investigated in detail. The present work describes investigations of the effects of NO2 on oxidation processes and the fate of NOx in a model lubricant system. NO2 acts as a free radical initiator which accelerates the initial rate of uninhibited hydrocarbon oxidation and increases the rate of antioxidant consumption in inhibited systems. NOx consumption increases after the end of the inhibition period. In addition, NO2 and NO react with oxidation intermediates or products in a complex series of reactions which can include direct reaction with antioxidants, formation of nitro‐oxidation products, conversion of NO2 to NO and regeneration of NO2 from NO. The significance of results obtained in this study with respect to mechanisms of oil degradation is discussed.
Antiwear properties of complex compounds of Sn(II) and Sn(IV) in lubrication of a bronze‐steel contact
Authors: Ozimina D. , Kajdas C.
Published: July 2006

The wear characteristics of metal‐organic chelate additives containing tin bonded to aliphatic dicarboxylic acids were investigated on a reciprocating motion test machine in lubrication of a steel‐bronze contact. It was found that both the valence state of the tin and the chain lengths of the dicarboxylic acids affected the wear results. All the compounds reduce wear effectively and, at pressures below 1.76 MPa, they assure zero ZDTP and SnDTP additives in the steel‐steel concentrated contact using the standard four‐ball machine.
A study of the antiwear action mechanism of alkoxy aluminium in lubricating oil
Authors: Dong J. , Chen G. , Luo F.
Published: July 2006

Aluminium is situated beneath boron in the same group of the periodic table. As borate is a good antiwear agent for lubricating oils, it is possible that aluminium compounds maybe possess antiwear properties similar to borate. After testing seven alkoxy aluminium compounds, the results support this assumption. The most efficient compound is triethoxy aluminium. When 2% mass of triethoxy aluminium is added to ISO VG 68 oil, the load wear index of a four‐ball machine increases from 219 N to 519 N and the weld point from 1568 N to 4900 N. This compound also exhibits good corrosion protection property. In the present work, after steel balls of a four‐ball machine were run in aluminium‐containing oil, the wear scars were analysed by scanning electron microscope and X‐ray energy dispersion analysis. The main compositions discovered on the scar surface were 5.7–48.3 atom % of iron, 4.4–11.2 atom % of aluminium, 37.1–59.1 atom % of oxygen, 8.7–23.5 atom % of carbon, and 0.3–1.1 atom % of chromium, under 3087 N–39 200 N of axial loads. When the loads are lower than 2450 N, the contents of oxygen are almost equal to zero and the contents of iron increase to 68.6–93.8 atom %. Based on the results of surface analysis and using thermodynamic principles, an antiwear action mechanism for triethoxy aluminium is suggested: under low loads, the weaker bond C‐C (350 KJ /mol) is broken, and the broken fragments may form polymer film during friction processes. As the loads increase, the stronger bond Al‐O (484.5 KJ /mol) is broken to create active aluminium and oxygen. The oxygen reacts with aluminium and iron to form a complicated solid solution containing AlxOY, FExOy on the surface. This complicated surface layer raises the weld point of the steel balls.
Some observations on the role of oxygen in lubricated wear
Authors: Willermet P. A. , Kandah S. K.
Published: July 2006

The role of oxygen in lubricated wear is discussed. Previous studies have shown that at low concentrations, oxygen can reduce wear, but at higher concentrations, it can increase wear. The situation is complicated by ZDTP antioxidants. The present paper reports experimental work aimed at elucidating the role of hydroperoxides ‐ whether they participate in the formation of wear‐resistant oxide films, if they (or peroxy radicals) are the main source of oxygen, and whether ZDTP‐hydroperoxide interactions in the wear zone are important in controlling wear.
The effect of molecular structure of n‐containing heterocyclic compounds on their wear properties
Authors: Ren T. , Liu W. , Xue Q. , Wang H.
Published: July 2006

The friction and wear properties of N‐containing heterocyclic compounds (indole, indazole and benzotriazole), which have the same cyclic structure except for the number of N atoms, added to alkylbenzene and to a mixture of liquid paraffin with 2 % wt succinimide dispersant were evaluated using a four‐ball machine. The N‐hexadecanoylindazole and N‐hexadecanoylbenzotriazole were synthesised, and their friction and wear properties in liquid paraffin were also evaluated. X‐ray photoelectron spectroscopy (XPS) was used to examine the binding energy of N1s on the rubbed surface. The effect of the presence of a lone electron pair of nitrogens in the compounds on antiwear property is discussed using the theory of molecular orbits.
An investigation of the effectiveness of antifriction additives in motor oils by laboratory methods and engine tests
Authors: Arabyan S. G. , Holomonov I. A. , Karaulov A. K. , Vipper A. B.
Published: July 2006

The antifriction properties of motor oils with different additives (oil soluble metal‐containing compounds, molybdenum disulphide and graphite dispersions, and ashless additives) were investigated by means of laboratory methods. The influence of additive concentration on their effectiveness is evaluated. The effect of the action of antifriction additives (friction modifiers) depends on the base oil and motor oil additive packages. The results of experiments are analysed using Auger spectroscopy. A mechanism of action of different types of friction modifiers based on analysis of the experimental data is proposed. Diesel engine tests of motor oils with antifriction additives were used to show the influence of these additives on fuel consumption. The results of engine tests with oils with different additives, and tests conducted on laboratory friction‐machines, are compared. A description of the laboratory methods and engine test methods used, as well as recommendations for their practical use in evaluating antifriction properties of motor oil additives, is given.
Characteristic effects of DDC lubrication
Authors: Tonder K.
Published: July 2006

This paper discusses deep disconnected cavities (DDC), a concept first introduced by the author. Disconnected shallow cavities or pockets have been treated by other authors, but the consequences of the extreme depths involved with DDC have not been recognised. The introductory paper established the existence of DDC effects. The latter are partly expressible as a slightly modified Reynolds equation, in which the film thickness function refers to the local minimum rather than the local mean customary in roughness analysis. In addition, the equation involves modifying factors which are independent of film thickness and other aspects of the macro‐geometry of the bearing, generating what may be interpreted as effective viscosities. The present paper establishes, by numerical studies, more exact expressions for the effective viscosities for a certain class of cavity geometry and distribution. The interaction of macro‐ and micro‐geometry is studied, showing that the optimisation of the cavity distribution depends on the macro‐geometry of the bearing. It is further shown, by a combination of analytical and numerical means, that the minimum frictional coefficient obtainable for a DDC bearing is that of its smooth counterpart when the two are running at the same minimum film thickness. If the two are lubricated by the same fluid and take the same load, a well‐designed DDC bearing will have a lower coefficient of friction than a similar smooth one.
The synergistic effects of EP and AW additives with a sulphurised steel surface under boundary lubrication
Authors: Ma Yan‐Sheng , Liu Jia‐Jun , Zheng Lin‐Qing , Wei Dan‐Ping , Wang Ru‐Lin , Zhang Xu‐Shou , Liu Hong
Published: July 2006

In this paper the synergistic effect on tribological behaviour of two additives, sulphurised olefin and tricresyl phosphate, in paraffin oil, and 1045 steel, treated by sulphurisation, was studied on a ball‐on‐disc test machine. An excellent load‐bearing capacity was obtained by the combination of sulphurisation and the lubricant paraffin+sulphurised olefin. The mechanism of this synergistic effect is discussed, based on micro‐analysis of the surface film by AES and XPS.
Antifriction action of lubricant additives
Authors: Vipper A. B. , Bartz W. , Karaulov A. K. , Mischuk O. A. , Lukinyuk M. Yu
Published: July 2006

The influence of antifriction additives for engine oils on fuel economy in gasoline engines has encouraged an interest in research into their action mechanisms. The influence of additives of different types on the antifriction properties of engine oils has now been investigated; additives have been discovered which effectively increase thermal stability of the lubricating layers and decrease friction coefficient, even at high temperatures.

The structure and composition of the surface layers of friction pairs have been studied with Auger electron spectroscopy. The inter‐relationship between the effectiveness of the antifriction action of the additives and their influence on the thickness and the composition of the surface layers has been ascertained. The most effective antifriction action was obtained where the thickness of the surface layers was reduced within certain limits, and where there was an optimisation of the oxygen and sulphur content. Certain regularities were established, since they were noticed while testing antioxidant, antiwear, antifriction, and detergent additives of different composition.
The effect of lubricants on deep drawability of zinc‐coated steel sheets
Authors: Muraki Masayoshi , Ide Hideo , Tagawa Kazuo , Nakamura Tamotsu
Published: July 2006

The effect of lubricants on deep drawability was studied for two types of zinc‐coated steel sheets on a high‐speed deep‐drawing machine. The drawability of galvannealed steel sheet, GA, at low speeds is significantly improved by friction modifiers, due to reduction in frictional forces around the die radius. In contrast to the results for GA, double layered steel, GAE, which has an Fe‐rich alloy coating on the top, and is superior to GA in terms of drawability, is insensitive to changes in the additives. This is mainly because the hardness of the upper coating layer of GAE decreases frictional resistance through a decline in the boundary contact area.
The hydrolytic stability of borates used as oil additives
Authors: Junbin Yao , Junxiu Dong
Published: July 2006

Eleven borate ester compounds were synthesised and their hy‐drolytic stabilities were compared. The results indicated that the hydrolysis problem of borate esters can be solved by introducing N, N‐dialkylamino‐ethanol with alkyl groups containing more than or equal to 4 carbon atoms in the esters. It was believed that the formation of a stable five‐member ring structure in molecules involving coordination of the nitrogen atom with boron contributes substantially to the resistance to hydrolysis of such compounds.
Elastohydrodynamics of lip seals
Authors: Salant Richard F. , Flaherty Andrew L.
Published: July 2006

A numerical elastohydrodynamic analysis of a rotary lip seal with microundulations reveals that the undulation pattern plays a central role in the operation of the seal. The undulations hydrodynamically generate elevated pressures within the lubricating film, providing load support, and deform in such a manner as to produce reverse pumping. The reverse pumping counteracts the flow induced by the sealed pressure, and thereby prevents leakage through the seal.

See p. 25 for the nomenclature.
Structure—performance relationships of viscosity index improvers: I microstructural determination of olefin copolymers by NMR spectroscopy
Authors: Kapur G. S. , Sarpal A. S. , Mazumdar S. K. , Jain S. K. , Srivastava S. P. , Bhatnagar A. K.
Published: July 2006

Five commercial olefin copolymer (OCP) viscosity index (VI) improvers have been characterised at the molecular level. The copolymer compositions have been determined using 1H and 13C‐NMR spectroscopy. The microstructural parameters, such as comonomer sequence distribution, number average sequence lengths and run number, have been determined by 13C‐NMR spectroscopy. NMR spectral editing techniques, e.g. Distortionless Enhancement via Polarisation Transfer (DEPT) have been used for peak assignments. This analytical approach aims at correlating the microstructural parameters with the physical properties and performance of these VI improvers, to be communicated later.
The contribution of new dispersant mixed polymers to the economy of engine oils
Authors: Pennewiß H. , Auschra C.
Published: July 2006

Mixed polymers have been concentrated to produce highly concentrated VI improvers based on polyalkyl methacrylates (PAMA) and olefin copolymers (OCP). Because of their liquid form and special viscosity/temperature relationship, these concentrates can be stored, shipped and processed at comparatively low temperatures. This, in combination with a high specific activity, favours the economic manufacture of multigrade oils.

In the VW elastomer compatibility test, the new dispersant mixed polymers (d‐MP2) show absolutely neutral behaviour towards fluoroelastomers. In gasoline as well as in diesel engines they contribute noticeably to the dispersant potential, thus making it easier to comply with the requirements for API SH. Moreover, bench and road tests have revealed a major reduction of engine wear. The effect of different dispersant groups is compared by way of a simple laboratory test and an attempt is made at corroborating a hypothesis on wear reduction.
Grease lubrication in isothermo‐elastohydrodynamic line contact
Authors: Dong Daming , Kimura Yoshitsugu , Okada Kazumi , Liu Wenyi
Published: July 2006

Elastohydrodynamic analysis is conducted and a numerical solution is presented for the film thickness in grease lubrication in isothermal, fully‐flooded rolling line contact with or without slip. By making use of a perturbational method, a modified Reynolds equation is established, which can be used with various constitutive equations if the equivalent viscosity can be expressed as a function of the shear rate. Verification of this analysis is carried out by experimentally determining the minimum film thickness with an X‐ray transmission technique, with satisfactory agreement. The effect of temperature on the apparent viscosity of grease is also discussed.
On thin film lubrication
Authors: Wen  , Shizhu
Published: July 2006

Various phenomena are revealed under EHL and micro‐EHL conditions, such as the properties of the lubricant under high pressure, traction, and the load‐bearing capacity of the lubricant film, and are discussed in the present paper. A new lubrication regime, thin film lubrication, has been discussed. The theoretical and practical significance of research on thin film lubrication is elaborated. Finally, the characteristics describing thin film lubrication and its main research directions are suggested.