bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmentally considerate ester lubricants for the automotive and engineering industries
Authors: Randles S. J.
Published: July 2006

Concern at the amount of lubricants lost in the environment has prompted the search for environmentally considerate lubricants, i.e. lubricants which biodegrade as a result of the biological action of living organisms. Various test procedures and parameters are discussed, and the performance of various lubricants, including synthetics, is presented.
Rheological properties of lithium, lithium complex, and sodium greases
Authors: Åkröm H. , Höglund E.
Published: July 2006

The rheological properties of two lithium, two lithium complex, and two sodium greases, all with the most common NLGI grade two, have been investigated. The greases are based on a mineral and a synthetic oil. The apparatus used was a cone‐and‐plate rheometer and an impacting‐ball apparatus.

The impacting‐ball apparatus used a steel ball, which impacted a lubricated sintered carbide plate, to measure the shear stress‐pressure coefficient, γ, of the lubricant. At pressures found in elastohydrodynamic contacts this coefficient determined the limiting shear stress. The γ‐value thus affects the coefficient of friction and consequently, lower γ‐value means less friction.

The results from the impacting‐ball apparatus showed that the γ‐value was lower for the greases with a synthetic base oil and that the lithium greases gave a lower γ‐value than the corresponding base oils.

Results from the cone‐and‐plate rheometer showed the characteristic shear thinning behaviour of the greases and the influence of shear history and temperature. The results from the cone‐and‐plate rheometer have also been fitted to a four parameter rheological model.
A new high‐stability synthetic phosphate ester
Authors: Shankwalkar Sundeep G. , Placek Douglas G.
Published: July 2006

Neutral phosphate esters are used as fire‐resistant basestocks in several applications including hydraulic systems, turbines, and compressors. They are also used as grease basestocks, and in hydrocarbon‐based lubricants and synthetic fluids as antiwear additives.

Development aspects of a new synthetic triaryl phosphate ester is presented in this paper. This product provides superior hydrolytic stability and lower volatility than existing commercial phosphate esters. Additionally, it has excellent oxidative stability and is fire resistant. The performance characteristics of the fluid suggest use of this phosphate ester as a high stability antiwear additive or lubricant basestock, and in any application where stability is of primary importance.
Polymer‐polymer friction: Adhesion dependence
Authors: Lavielle L. , Lamouri S.
Published: July 2006

The friction of pure polyethylene and acrylate grafted films or mixtures of polyethylene and a poly (ethylene‐butylacrylate‐maleic anhydride) terpolymer is examined at low speed for sliding on a poly(methylmethacrylate)(PMMA) or polyvinylchloride (PVC) substrate. In all cases, the friction coefficient μ at equilibrium is proportional to the adhesion energy of the same films as determined by a peel test. This study shows how much for smooth surfaces, interfacial and mechanical properties intervene simultaneously in polymer‐polymer friction.
Role of synthetic esters in the overall performance of cold rolling oil for steel
Authors: Mahanti S. , Datta N. , Pandey N. , Barman S. , Maiti N. , Nambiar P. R.
Published: July 2006

Cold rolling mill productivity and product quality depend on the lubricant chemistry and composition, as well as on such physical factors as operation and maintenance. This paper discusses new requirements for rolling mill oils. Ester‐based rolling oil formulations have been developed and their performance is evaluated, notably in respect of lubricity, strip cleanliness, and emulsion stability. Changes in these properties during operation and storage are also considered. It is found that the properties are greatly influenced by chemical constitution and the fat‐to‐ester ratio.
Synthetics basics: Polyalphaolefins — base fluids for high‐performance lubricants
Authors: Benda R. , Bullen J. , Plomer A.
Published: July 2006

Polyalphaolefins or PAOs are saturated oligomers manufactured via the catalytic oligomerisation of alphaolefins. An oligomeric mixture is obtained which is then hydrogenated and distilled to produce a range of PAOs. These synthetic fluids are differentiated and graded by their viscosities at 100°C. PAOs are mainly used as high‐performance functional base fluids in engine lubricants, gear oils, hydraulic oils, automatic transmission oils, compressor/pump oils, and greases.

Automotive engine (crankcase) lubricants represent the biggest market for PAOs and here they compete with petroleum‐based oils. When compared to mineral oils, PAOs exhibit a number of inherently superior physical and chemical properties, such as greater fluidity at low temperature, lower volatility, a higher viscosity index, a lower pour point, better oxidative/thermal stability, low toxicity, and biodegradable low viscosity grades.

This combination of properties means that PAOs enhance the formulator's ability to produce high‐performance lubricant oils. Some examples of performance benefits obtained from PAO‐based formulations have been shown to match and even exceed the performance of higher cost traditional ester‐based oils when tested under the new Japanese Automobile Standards Organisation (JASO) FC two‐stroke specifications. Low viscosity automotive engine oils, which can only be formulated with PAOs, can produce a fuel saving of >2% when tested under US Federal Test Procedure (USFTP) 75.
Thermal‐oxidative characteristics of some high‐temperature diesel lubricants
Authors: Li H. , Hsu S. M. , Wang J. C.
Published: July 2006

Many advanced engine concepts require lubricants that function in a hightemperature environment. The thermal‐oxidative characteristics of some lubricants formulated for such purposes have been studied by a new thermogravimetric analysis (TGA) procedure. Factors affecting the stability of lubricants at elevated temperatures were incorporated into the experimental design. Information extracted from the TGA was able to provide insights into the thermal stability, oxidative stability, and oxidative volatility of lubricants. The merits of the technique were demonstrated by examining data obtained from engine tests simulating the operating conditions of the low‐heat‐rejection (LHR) engine. These engine test data confirmed that the NIST TGA is a useful tool in studying or formulating lubricants designed for high‐temperature applications.
High viscosity polymer esters as an alternative to PAO 100
Authors: Wallfahrer U.
Published: July 2006

High viscosity polymer esters were studied as an alternative to PAO 100. High viscosity polyalphaolefins have the disadvantage of poor compatibility with additives. High viscosity polymer esters have now been developed which are compatible with polar and non‐polar elements. The properties of the base oils were tested, as were trial formulations of automotive gear oil and industrial gear oil.
A comparison of fire‐resistant hydraulic fluids for hazardous industrial environments. Part I. Fire resistance and lubrication properties
Authors: Phillips W. D.
Published: July 2006

Fire‐resistant hydraulic fluids have been developed since the Second World War. In addition to phosphate esters, there are various other fluids (e.g. oil‐in‐water emulsions, water glycols) available. This paper provides a technical comparison of the different fluid types, in terms of fire resistance, lubricating properties, and viscosity. The second part of the study examines the corrosion properties, thermal and oxidative stability, shear stability, materials compatibility, and other physical properties.
Investigation into the scuffing load capacity of environmentally‐friendly lubricating oils
Authors: Kozma M.
Published: July 2006

The present paper looks at the nature of scuffing, and the factors influencing it, for both hot scuffing and cold scuffing. The influence of surface layers and finishes in relation to this phenomenon are discussed, and some preliminary results are presented for cold scuffing tests, with various steels, for a mineral oil, a rapeseed oil, and a vegetable‐based oil.
A comparison of fire‐resistant hydraulic fluids for hazardous industrial environments. Part II. Stability, fluid life, and environment
Authors: Phillips W. D.
Published: July 2006

Fire‐resistant hydraulic fluids have been developed since the Second World War. In addition to phosphate esters, there are various other fluids (e.g. oil‐in‐water emulsions, water glycols) available. This paper provides a technical comparison of the different fluid types, in terms of fire resistance, lubricating properties, and viscosity. The second part of the study examines the corrosion properties, thermal and oxidative stability, shear stability, materials compatibility, and other physical properties.
Gas chromatography with an atomic emission detector for turbine engine lubricant analysis
Authors: Keller Michael A. , Saba Costandy S.
Published: July 2006

Lubricants and/or additives may need characterisation, or detection of contaminants and their identification. Analysis of turbine engine lubricants using Gas Chromatography with an Atomic Emission Detector (GC‐AED) is shown to be a function of the versatility of its multi‐element detection ability, and to offer advantages over previously used chromatographic detectors. GC‐AED can reveal identity of elements, and this paper presents GC‐AED results for MIL‐L‐7808 turbine‐engine lubricants, and for some thermally stable hightemperature candidate organic compounds — polyphenyl ether, phenyl thioethers, and cyclotriphosphazenes.
Cram be abyssinica oil and its derivatives as renewable lubricants: Synthesis and characterisation of different esters based on crambe fatty acids
Authors: Bondioli P. , Inzaghi L. , Postorino G. , Quartuccio P.
Published: July 2006

The authors have studied the possibility of using Crambe abyssinica oil as a starting material for synthetic lubricants, and in this paper the procedures for the preparation of monoesters from methyl, ethyl, isopropyl, and 2‐ethylhexyl alcohol, as well as diesters from neopentylglycol, triesters from trimethylolpropane and tetraesters from pentaerythritol, are described. The different reactions were set up using free fatty acids, methyl esters, and Crambe oil as starting materials. All reactions were carried out in a solvent‐free medium, using normally available catalysts and under experimental conditions which could easily be scaled up to industrial level. All the products obtained, along with the refined Crambe abyssinica oil used as a reference, were analysed for viscosity, viscosity index, low‐temperature behaviour and oxidative and hydrolytic stability. Results of tests, such as four‐ball machine and Noack, are reported. The results show that several products covering a wide range of different applications can be obtained from the basic Crambe abyssinica oil, and, furthermore, the chemical modification of the Crambe abyssinica oil can, in some cases, improve thermal and hydrolytic sensitivity and even the tribological properties.
Advanced low viscosity synthetic passenger vehicle engine oils
Authors: Bergstra R. J. , Baillargeon D. J. , Deckman D. E. , Goes J. A.
Published: July 2006

Premium quality synthetic passenger vehicle engine oils have been marketed by the authors' company since the early 1970s. During this time, the performance benefits of synthetic‐based engine oils have been documented in a wide variety of engine and vehicle tests. The purpose of this paper is to demonstrate that, with the use of synthetic base oils and advanced additive technology, low viscosity oils can be formulated that have high fuel efficiency but which retain superior engine protection and performance reserves. Specifically, two synthetic engine oils, an SAE OW–40 and an SAE OW–30, have been developed that exceed the highest industry standards in both US (AP1)and European (ACEA) fuel economy and durability engine tests. The high quality of this technology is demonstrated in industry‐standard engine and laboratory performance tests, as well as non‐standard tests, such as extended‐length engine tests, vehicle fuel economy tests, high mileage chassis rolls tests, and extended oil drain ‘over‐the‐road’ vehicle tests.
Ecological cutting: Feasible or not?
Authors: De Bruyn K. , Crauwels N. , Van Stappen M. , Perremans P. , Celis J. P. , Stals L.
Published: July 2006

This paper describes the results of a two‐year research project on ecological cutting, in which four different applications, namely, cutting, pocket milling, face milling, and drilling, were investigated under dry and lubricated conditions. A traditional cutting fluid and an environmentally friendly cutting fluid were used for the latter. TiN‐, Ti (C,N), and (Ti,Al)N‐coated tools were tested, together with commercially‐available multilayer coated tools, to analyse to what extent the use of coatings could reduce or even eliminate the need for cutting fluids. The machined materials include an unalloyed steel, I.0503, a low alloyed steel, 1.2312, a stainless steel, 1.4306, and cast iron, ADI. End‐of‐ life tests were done in all cases and the wear of the tools was examined with SEM. The research showed that the results are strongly dependent on the application. For cutting, coated tools result in the best tool lives although tools used under lubricated conditions still outperform their dry used counterparts. For milling, dry machining is advantageous. The drilling tests showed better results under lubricated conditions mainly due to the cooling and chip removal capacity of the lubricants. In this case, the (Ti,Al)N‐coated drill out‐performed the commercially available coated tool.
Suitability and environ mental compatibility of rapeseed oil based hydraulic fluids for agricultural machinery
Authors: Remmele Edgar , Widmann Bernhard
Published: July 2006

Hydraulic fluids based on rapeseed oil tend to oxidise and hydrolyse, especially at temperatures above 80°C. Long‐term testing, with thirty‐seven agricultural machines, of an Esso PFL hydraulic fluid was carried out to investigate the suitability of rapeseed oil based hydraulic fluids. The operating conditions, notably the kind of work being done and the thermal regime of the hydraulic fluids, were monitored for each machine. Oil refill quantities, repairs, and maintenance were also documented. Samples of the hydraulic fluids were analysed for technical characteristics and element content. Unused rapeseed oil based hydraulic fluids are more rapidly biodegradable and less toxic than mineral oil based hydraulic fluids. However, hydraulic fluids most often come into contact with the environment when they are used, either through accidents or through oil dripping from the hydraulic couplers. It was, therefore, the purpose of a second research project to investigate the environmental impact of rapeseed oil based hydraulic fluids in the course of use. Four rapeseed oil based hydraulic fluids were tested in the field on eight agricultural machines. The relevant operating conditions, such as thermal changes and pressure load, were monitored, and oil samples were analysed, as in the first project. Biodegradability was tested with the CEC L‐33‐A‐94 test and the OECD 302 B test (the Zahn‐Wellens method). Aquatic toxicity was determined by different test systems: waste water bacteria, photobacteria, plankton alga, garden cress, Daphnia, and Leuciscus. It was found that, generally, the candidate hydraulic fluids were suitable for use in the machines tested. It was also found that high biodegradability and low ecotoxicity were constant properties throughout the test period. Thus, the hydraulic fluids tested are suitable for application in agricultural machinery.
On the feasibility of using cryo‐treatment as a tool to enhance the abrasive wear behaviour of solid‐lubricated polymeric composites
Authors: Indumathi J. , Bijwe J. , Ghosh A. K.
Published: July 2006

Cryo‐treatment, a bulk modification technique, is fast emerging as a way with which to improve the wear resistance of metals. This technique has also shown the ability to enhance significantly the abrasive wear performance of some polymers and their short glass‐fibre reinforced composites. In this work, short carbon‐fibre reinforced composites of some heat resistant polymers, such as polyetherimide, polyethersulphone, polyamide 6,6, polyetheretherketone, and polytetrafluoroethylene, were selected to explore the potential of cryo‐treatment. The selected materials were cryogenically treated by cooling them to the temperature of liquid nitrogen. The abrasive wear tests were carried out at ambient temperature in single pass conditions at various loads, on a pin‐on‐disc machine, using silicon carbide paper as a counterface. The investigations revealed that this technique has definite potential to increase the wear performance of carbon‐fibre reinforced composites. An increase in hardness due to cryo‐treatment was thought to be responsible for an observed improvement in wear performance. However, the extent of improvement in the wear performance was not matched by an increase in the hardness value. Scanning electron microscopy proved useful in examining the morphological changes in the composites due to cryo‐treatment.
Thermo‐oxidative stability of high‐temperature stability polyol ester jet engine oils — a comparison of test methods
Authors: Bartl P. , Völkl Chr.
Published: July 2006

Thermo‐oxidative stability in aerospace turbine oils is an important criterion. A new category (HTS) of turbine oil has been introduced, and the present work compares data on the oxidation stability of HTS oils obtained using the FTM 791, method 5308 test, at various temperatures, and PDSC experimental data, to standard class oils (STD). PDSC has become established in recent years as an effective means with which to establish the thermo‐oxidative stability of oils. The purpose of the present work was to find out whether PDSC could identify HTS oils correctly, and also to increase our understanding of some of the chemical processes behind the test results. Analogies in the degradation of the oligomer antioxidants have been confirmed by MALDITOF mass spectra.
The tribological behaviour and mechanism of action of sulphur‐containing borate esters in rape seed oil
Authors: Gong Qingye , Yu Laigui , Ye Chengfeng
Published: July 2006

Three sulphur‐containing borate esters and one borate ester based on boric acid and n‐octanol were synthesised. The antiwear and friction‐reducing properties of these synthetic compounds as additives in rape seed oil were examined using a four‐ball machine. The relationship between the additive structure and tribological properties was explored, and the lubrication mechanisms of the additives investigated. The worn surfaces of a steel ball lubricated with the additive‐containing rape seed oil were analysed using X‐ray photoelectron spectroscopy and scanning electron microscopy. The elemental compositions of, and distributions in, the worn steel surfaces were determined with an electron probe micro‐analyser. It was found that sulphur‐containing borate esters as additives in rape seed oil at appropriate concentrations can be effective in improving antiwear and friction‐reducing behaviour. The rape seed oil base stock experiences competitive adsorption and tribochemical reactions with additives on the rubbing steel surface. The introduction of the active element sulphur into the borate ester additives functions to improve the tribological behaviour of the base stock by increasing the rate of formation of a protective layer on the rubbing steel surface. However, the tribological behaviour of the additives is not dependent on the number of sulphur atoms in the additive molecules, and further work is needed to investigate the possible dependence of this behaviour on the ratio of boron to sulphur in the additive molecules.
Friction and wear of PTFE seal materials
Authors: Haiser H. , Haas W.
Published: July 2006

Shaft seals made from polytetrafluoroethylene (PTFE) materials, called PTFE lip seals, have been successfully used for decades in the chemical industry. Owing to their chemical and thermal stability, PTFE lip seals are used instead of elastomeric lip seals in many automotive and hydraulic applications. This paper deals with the fundamental tribological properties and effects of filled PTFE materials employed in rotary shaft seals, mainly on the basis of experimental work done in the authors' laboratory. The tribological components of a sealing system and the main influences on the sealing function are briefly surveyed. The test methods and conditions used are also described. The experimental results show that the fillers used in the PTFE compounds, as well as the topography of the shaft, play a crucial role in fluid sealing.
Tribological behaviour of polyalphaolefins: Wear and rolling‐contact fatigue tests
Authors: Fernández Rico E. , García Cuervo D. , Hernández Battez A.
Published: July 2006

Polyalphaolefin (PAO) fluids have become widely accepted as high‐performance lubricants and functional fluids due to certain inherent, and highly desirable, characteristics. One of these characteristics is their low toxicity, which, combined with excellent viscometrics and lubricity, have made low‐viscosity PAO fluids an important component in lubricant formulations.

Typical data found in product specifications for lubricants are the kinematic viscosity and the viscosity index. These values do not give enough information with which to choose the optimum lubricant for a lubricated contact. In mechanical systems, rolling, sliding, and rolling/sliding contacts occur, and lubricants have to work optimally under these operating conditions.

In this study the rolling‐contact fatigue lives (L50 and L10) of PAOs of different viscosities were experimentally determined. The tests were carried out using a four‐ball machine. Wear tests were also carried out using another four‐ball tester in order to measure the wear‐scar diameter and the flash temperature parameter. The lubricants were characterised by infrared spectroscopy, and the pitting of the balls was observed using scanning electron microscopy.
Performance of synthetic oils in the hydrodynamic regime — 1. experimental
Authors: Glavatskih Sergei B. , Larsson Roland
Published: July 2006

An investigation of the performance of environmentally adapted synthetic oils in the hydrodynamic lubrication regime has been carried out. Four oils have been tested: polyalphaolefin and ester based ISO VG46 oils as well as mineral ISO VG68 and VG46 oils. Tests were conducted in a facility containing two identical tilting‐pad thrust bearings typical of the design in general use. The differences between the mineral and synthetic oils in terms of maximum operating temperature, minimum oil film thickness, and bearing power loss have been examined. Substitution of the mineral ISO VG68 oil with an ISO VG46 oil slightly reduces the bearing operating temperature. This is due to a decrease in the basic viscosity. It is concluded that the ester base ISO VG46 oil can be used as an environmentally adapted replacement for the mineral ISO VG68 oil without sacrificing bearing safety. Such a change also offers noticeable energy savings. If the ester based oil is used instead of a mineral oil of the same viscosity grade, bearing reliability is improved by the increased oil film thickness.
The properties of various antiwear and extreme‐pressure additives in pentaerythritol ester
Authors: Min Xu , Di Li
Published: July 2006

The tribological properties of three representative antiwear and extreme‐pressure additives, tricresylphosphate (TCP), triphenylthiophosphate (TPPT), and α‐mercaptobenzothiazole (MBT), in pentaerythritol ester at different concentrations were studied. It was found that TCP could react with Fe to form an organic phosphate film containing 4% P on the scar surface, while TPPT formed a blended organic phosphate and inorganic FeS film, containing 4% P and 6% S, respectively. MBT formed an inorganic FeS film containing 45% S. Ferrographic analyses of wear particles collected from oil samples after four‐ball tests showed that the higher the temperature the better the tribological performance of the additivated ester, due to its reaction with the metal surface.
European ecolabels for biodegradable hydraulic oils — a challenge to base material producers and formulators
Authors: Bongardt F. , Willing A.
Published: July 2006

‘Ecolabels’ are a means to guide the user to more environmentally favourable products. With regard to lubricants, the German Blue Angel UZ‐79 and the Swedish standard SS 155434 for biodegradable hydraulic fluids are perhaps the most important. Whereas the Blue Angel is optional, the Swedish standard SS 155434 is a legal requirement: hydraulic fluids not fulfilling the criteria of SS 155434 are not permitted on the Swedish market. Version 4 of SS 155434, which came into effect in July 2000, introduced new and more stringent ecological requirements. In view of the growing importance of the Swedish market for biodegradable hydraulic oils, the authors' company launched a research programme in early 2000 with the aim of offering SS‐155434‐compliant oleochemical base oils by the end of the year.

First, the effects and the plausibility of the new assessment criteria for the ready biodegradability of raw materials were studied. A systematic comparison based on chemical oxygen demand (COD) and theoretical oxygen demand (ThOD) evaluations confirmed that unqualified reliance on the COD parameter can lead to false positive evaluations. The studies also showed, however, that results based on COD determined by chemical analysis are valid, provided a suitable oxidation method is used and the completeness of the oxidation is carefully monitored.

Moreover, it was shown that the required use of the reference parameter ThOD does not necessarily require complicated elementary analyses of the test substance. Even in the case of oleochemical products with indefinable structural formulas (C‐chain fractions, alkoxylated compounds), structural estimates enabled sufficiently accurate ultimate oxidation values to be calculated. The studies also showed that the restriction to only two degradation test methods is scientifically unfounded. An extension of the approved test methods to include the scientifically accepted CO2 headspace test and two‐phase closed bottle test would enable existing data to be used without detracting from the environmental standard.

On the basis of more recent degradation studies, it has been shown that synthetic esters, especilay various saturated and unsaturated TMP fatty acid esters, satisfy the stringent sriteria of the new SS 155434, Supplementary studies of low‐viscocity XXX‐oils (hydrocrackates) and mixtures of XXX‐oils and synthetic esters indicated that this product class could be optimised to make it satisfy the criteria of the Swedish ecolabel.
Alkylated naphthalenes as high‐performance synthetic fluids
Authors: Hessell E. T. , Abramshe R. A.
Published: July 2006

The physical and chemical properties for a series of structurally well‐defined, alkylated naphthalenes have been compared. Structural characteristics, such as the alkyl chain length, alkyl chain branching, and number of alkyl groups on the naphthalene ring, have been correlated with physical properties, such as viscosity, viscosity index, pour point, and aniline point. The thermo‐oxidative stability of the alkylated naphthalenes was evaluated by the rotating pressure vessel oxidation test (RPVOT), a bulk oxidation test (BOT), and pressure differential scanning calorimetry (PDSC). Although all of the alkylated naphthalenes showed better thermo‐oxidative stability than other traditional hydrocarbon‐based fluids, the relative performance of the structurally different alkylated naphthalenes was found to be test dependent. Initial RPVOT studies with a linear polyalkylated naphthalene show that it gives good additive response to the incorporation of traditional antioxidants.
Coated gearings and bearings optimised for environmentally acceptable lubricants
Authors: Weck M. , Hurasky‐Schönwerth O. , Bugiel C. , Krell M. , Spechtel B. , Boutemy F.
Published: July 2006

Gearings and bearings are machine elements that are subjected to heavy tribological stresses. The pressures are high in the rolling contacts of these machine elements, and this leads to slippage between the surfaces of the contact partners. Correspondingly, the demands on the lubricants are also quite high. Nowadays, additives are used to reduce the friction and wear. However, the biodegradability of additivated lubricants is often not known, although the use of such lubricants can be critical for the environment. The objective of the investigations described in the present paper is to find a way of using lubricants with as few additives as possible but without decreasing the capability, reliability, and life of the machine elements. Thin coatings seem to be a good solution to substitute for the additives. The wear protection of coatings is investigated here with respect to gearings and spindle bearings for machine tools.
Friction and film‐forming behaviour of five traction fluids
Authors: Anghel V. , Glovnea R. P. , Spikes H. A.
Published: July 2006

There is growing interest in the use of toroidal‐type traction drives to provide continuously variable transmissions for use in medium‐ to high‐power automotive engines. These transmissions require the use of specially designed traction fluids to provide high friction in full‐film elastohydrodynamic lubricated contacts. This study has measured the film‐forming and traction properties of five commercially available and developmental traction fluids to provide data needed to predict their performance in traction drives. Some differences in performance between the fluids have been noted.
Investigation of the torque capacity of automatic transmission fluids with various oil additives
Authors: Shengxue Hu , Xisheng Fu , Mei Zhang , Lei Guo , Weimin Liu
Published: July 2006

A slip‐controlled lock‐up clutch system is very efficient in improving the fuel economy of automatic transmission‐equipped vehicles. However, a special automatic transmission fluid (ATF), which combines anti‐shudder properties with a high torque capacity, is required for such a system. An ATF with various oil additives was formulated, the torque capacity of which was evaluated. The results show that certain additives, especially sulphur‐containing extreme‐pressure and antiwear additives, have an important effect on the torque capacity. Analyses by X‐ray photoelectron spectroscopy of the steel surfaces tested clearly reveal the presence of the elements carbon, sulphur (S2−, S6+), oxygen, nitrogen, phosphorus, boron, and calcium. Among them, sulphur and phosphorus have the more important effects on the torque capacity of the ATF, while the presence of nitrogen is important with regard not only to torque capacity but also to antiwear characteristics.
Effects of sunflower oil added to base oil on the friction coefficient of statically loaded journal bearings
Authors: Durak E. , Çetinkaya M. , Yeinigün B. , Karaosmanoǧlu F.
Published: July 2006

In this study, sunflower oil at different concentrations of between 1 and 50% was added to base oil to obtain lubricating oil candidates. The lubricating oil candidates were characterised by ASTM methods, and their effects on the friction coefficient at 25 and 100°C at different speeds and loads in a statically loaded journal bearing were determined. The technological characteristics of the sunflower oil were determined according to standard methods.

The study shows clear evidence that the modification of friction by sunflower oil is at least equivalent to that by mineral oil, and the lubricationg oil candidates containing sunflower oil show a reduction in the coefficient of friction.
Effect of the chemical structure of fluorinated esters on the tribological properties of a steel‐on‐steel system
Authors: Zhu J. M. , Liu W. M.
Published: July 2006

The effect of the chemical structure of fluorinated esters on the friction and wear behaviour of a steel‐on‐steel system was investigated. The friction and wear testing of a steel disc sliding against a counterpart ball of the same steel was carried out using an Optimal SRV oscillating friction and wear tester. The chemical features of the worn steel surfaces were analysed by means of X‐ray photoelectron spectroscopy, and the morphologies and elemental compositions of the worn steel surfaces observed and determined using scanning electron microscopy. The results indicate that a fluorinated ester with methylene groups that are not substituted by fluorine in the acid structure gives the best friction‐reducing behaviour and a keto‐ester shows the best antiwear properties.
Antiwear performance of modern industrial gear oils
Authors: Matsuo K. , Yoshida A. , Obata F.
Published: July 2006

Thermally refined gears were tested under the effects of various modern industrial gear oils, viscosity 1SO VG 220. The wear of the gears was measured for each oil, including tooth surface roughness and the tooth fillet strain of the pinion. It is concluded that graphite additivated gear oil shows excellent wear resistance and surface roughness over sulphur‐phosphorus and organic Mo compound added oils, as well as less iron oxide.
Developments in the field of hydrogenated diene copolymers as viscosity index improvers
Authors: Eckert R. J. A. , Covey D. F.
Published: July 2006

This paper briefly reviews the development of linear hydrogenated diene copolymers as VI improvers, and reports on a novel class of VI improvers, the hydrogenated, star‐branched polyisoprenes. The viscometric properties of multigrade oils containing such products and their performance in gasoline and diesel engines will be described.
Metalworking additives: A new approach to EP properties
Authors: Clason D. L.
Published: July 2006

Work in the author's laboratory has shown that certain specially designed overbased sulphonate‐compounds function as extreme pressure agents in heavy duty metalworking operations. Depending upon the application, these materials may be used individually or in combination with conventional EP agents; they have also shown a synergism with active sulphur compounds. Film strength tests, controlled tool life evaluations, and field trials confirm that high load‐bearing properties are imparted to metalworking fluid formulations. In addition, we have seen dramatic effects on the quality of machined metal surfaces. As an extremely important benefit, these unconventional extreme pressure agents are environmentally acceptable.
Additive‐additive and additive‐surface interactions in lubrication
Authors: Spikes H. A.
Published: July 2006

Combinations of additives are often found to exhibit antagonistic or synergistic effects compared to the performance of the individual additives. This paper reviews the state of knowledge concerning such effects. Direct interactions, where two additives combine at a molecular level, are distinguished from complementary or exclusary effects where the individual contributions of separate additives enhance or reduce overall performance but with no direct interaction. Additive interactions take place in solution and at surfaces, and both are discussed.
Acceleration of wear of steel with fatty acid and oxygen under rolling with sliding partial EHD conditions
Authors: Masuko M. , Shiomi S. , Okabe H.
Published: July 2006

Quantitative evaluation was used to study the effect of surface roughness on wear behaviour of steel under rolling with sliding partial EHD conditions, and to clarify the effect of an additive and operating environment. It was found that the wear behaviour under conditions of lubrication with mineral oil was governed by the oxidation of the surface, regardless of whether the lubricant was formulated was with or and without additive. It was also found that wear was accelerated by the addition of fatty acid in the presence of oxygen, whereas it was not affected for lubrication with additive‐free mineral oil. It is considered that the acceleration of wear by addition of fatty acid is closely related to the oxidation of the surface during friction.
Lubricated wear of PTFE and graphited PTFE
Authors: Sethuramiah A. , Awasthy K. L. , Prakash Braham , Mahapatra P. K.
Published: July 2006

Tribological behaviour of PTFE and graphited PTFE have been evaluated under lubricated conditions and compared with dry wear. The stress selected is in the range of 0.44 to 1.64 MPa, and the data generated are relevant to conformal contacts. Mineral oil lubrication can reduce wear of PTFE by one to two orders of magnitude. With graphited PTFE the lubricant effect is lower in comparison to that observed with PTFE. Specific wear rates are plotted on a histogram.
The relationship between chemical structure and effectiveness of some metallic dialkyl‐ and diaryl‐dithiophosphates in different lubricated mechanisms
Authors: Born M. , Hipeaux J. C. , Marchand P. , Parc G.
Published: July 2006

The antiwear (AW) and extreme‐pressure (EP) properties of some metallic dialkyl‐ and diaryldithiophosphates (MDTP), including zinc, have been studied in different metal/metal contact conditions: four‐ball and FZG rigs.

It was noted that with pure dialkyldithiophosphates of different divalent metals (Zn, Cd, Cu, Pb, Ni, Co), prepared from the same alcohol, four‐ball, EP results, expressed in terms of load‐wear index, show that the highest performances are obtained with ZnDTP, but, statistically, the higher the ionic radius of the metal, the better the performance, while EP results, expressed in terms of weld load, do not show any difference between the MDTPs. Four‐ball AW results, expressed in terms of wear scar, show that the highest performances are obtained with ZnDTPs; beyond a certain value these performances with Zn and Pb are almost independent of the concentration. For the other metallic DTPs, there is a very close relationship between performance and concentration.

On the FZG gear rig, EP‐AW results, expressed in terms of failure load stage and specific wear, show that statistically, the higher the ionic radius of the metal, the better the performance. With ZnDTP four‐ball, EP results, expressed in terms of load wear index, do not depend on the chemical structure of the alcohol used for synthesised ZnDTP, but, if results are expressed in terms of weld load, better performances are obtained with ZnDTP synthesised from secondary alcohols. AW results show that the effectiveness of ZnDTP from secondary alcohols is slightly higher when the alcohols used contain less than six carbon atoms. Beyond six carbon atoms in primary or secondary alcohol molecules, performances decrease. FZG, EP‐AW results show that performance does not depend on the primary or secondary nature of the alcohols used, and that the smaller the hy‐.
Influence of different friction conditions on the process of cold backward extrusion of steel
Authors: Plancak M.
Published: July 2006

Backward extrusion of steel is a deformation process in which very high forces and tool pressures occur. Reduction of such high forces and tool pressures is possible by using an efficient lubricant. This paper describes an experimental investigation of the influence of different lubricants on the stress‐strain state within the workpiece volume as well as on the stressing of the die. Best results were obtained when a phosphate‐coated specimen was lubricated with MoS2.
Effect of consolidation in boundary lubrication
Authors: Georges J. M. , Mazuyer D. , Loubet J. L. , Tonck A.
Published: July 2006

This paper is concerned with the effects of the colloidal aspect in boundary lubrication. The newly developed method for surface forces measurement has clearly shown the consolidation effect during contact loading.

The paper also shows that, in some cases, the friction coefficient varies with the compaction of wear particles in the contact. Friction experiments between a ball and flat (both sapphire) in which the contact is immersed in water, have been performed to understand the effect of compaction of worn material on friction. During friction, wear debris is piled up in the contact and shear behaviour depends on pressure and volume fraction of wear particles.
Soluble molybdenum compound and sulphur ep additive combinations: Synergistic and adverse effects on antifriction and antiwear characteristics
Authors: Sarin R. , Gupta A. K. , Sureshbabu A. V. , Martin V. , Misra A. K. , Bhatnagar A. K.
Published: July 2006

Antifriction and antiwear performance of three soluble molybdenum (Mo) compounds (Mo dithiophosphate, Mo dithiocarbamate and Mo amine complex) and four sulphur‐containing EP additives (sulphurised isobutylene, dibenzyl disulphide, sulphurised fat and synthesised ethylene sulphur derivative) have been studied, alone and in combination, using an SRV test rig. The additive behaviour in combination has been found to be selective, and dependent on the chemistry and ratio of the additive components. Certain sulphur EP additives in combination with Mo compounds have exhibited a synergistic effect. The antifriction performance of additives, in general, has been found to be further enhanced at higher test temperatures. However, a reduction in antiwear property has been noticed.
Reliable model of lubricant‐related friction in internal combustion engines
Authors: Benchaita M. T. , Lockwood F. E.
Published: July 2006

A linear model of lubricant‐related engine friction was developed. Based on lubrication fundamentals, the technique is comprised of three simple bench tests that respectively operate under thick fluid‐film hydrodynamic lubrication, elastohydrodynamic lubrication, and boundary lubrication. With adequate configuration and appropriate test conditions, these bench tests are seen to simulate major friction losses in a typical internal combustion engine.

Lubricant characteristics obtained in the bench tests were combined using SAS linear regression and correlated to ASTM Five‐Car and Sequence VI engine tests. The linear model gave an excellent prediction of engine data. It further showed that hydrodynamic friction losses dominate lubricant‐related engine friction, followed by boundary friction losses, and elastohydrodynamic or mixed friction losses. This simple, reliable, and inexpensive technique can be used as a research tool to study friction characteristics of crankcase lubricants and to develop superior fuel‐efficient engine oils.

Major findings from this study can be summarised as follows:

The linear model predicts that 5 to 6% fuel economy improvement over the industry high reference oil HR‐4 is achievable with today's motor oil technology

Hydrodynamic friction losses in both ‘thick' and ’thin' fluid‐film lubrication account for 63% of total friction losses caused by the engine oil while boundary friction losses amount to 37%.

Friction losses in the elastohydrodynamic (EHD) engine are significant, up to 22% of total friction losses. This, combined with the fact that EHD film thickness is the most significant parameter in the linear model, suggests that pressure effects (ie, high‐temperature/high‐shear/high‐pressure viscosity, pressure‐viscosity coefficients) are important.

Increasing fuel economy improvement is in general in the order: SAE 10W–40 < SAE 10W–30 < SAE 5W–30, providing that base stock and additive systems are unchanged.
Computer modeling of rheological properties of base oil compositions with selected additives
Authors: Kajdas Czeslaw , Warsaw Roman Kempinski
Published: July 2006

An analysis of the rheological properties of various oils and their formulations with selected rheological additives (Visconyl‐200 and ECA‐6911) was performed. Base oils (OS and OU) obtained on a large laboratory scale were the primary subject of the investigation. They were produced according to classical and modified base oil technologies. The modification introduced an additional process of mild oxidation of atmospheric residue before vacuum distillation. Other oils, such as aromatic and saturated hydrocarbons separated from the OS and OU oils, as well as oil fractions (1S–5S and 1U‐5U) obtained from the base oils by vacuum distillation, have also been investigated.

Using the rheological properties determined for the distillate oil fractions formulated with the Visconyl and ECA additives, the empirical formulae describing the dependence of kinematic viscosity v50, c and v100, c and of the pour point of the compositions, on the basic physico‐chemical properties of the base oils, and on the type and concentration of additive, have been found. The theoretical viscosity index values of the oil compositions were also characterised indirectly by using the empirical formulae describing kinematic viscosities of the compositions at 50 and 100°C. The formulae obtained were successfully tested with several selected base oils.
The characterisation of synthetic sulphonate and phenate detergents by nuclear magnetic resonance and infrared spectroscopy
Authors: van de Ven A. M. C. , Johal P. S. , Jansen L.
Published: July 2006

Sulphonate and phenate detergents are used in many modern oil formulations. Overbased sulphonates form micelles, whereas in overbased phenates the excess metal carbonate is incorporated in the molecule as a carbonate chain. This is the cause of broad unresolved peaks in the NMR spectra of these detergents. Hydrolysis removes the excess metal carbonate and converts the sulphonates and phenates to sulphonic acids and phenols respectively. Especially in the 1H‐ and 13C‐NMR spectra, a substantial resolution enhancement is achieved after hydrolysis. These spectra reveal much more structural information. One of the features that can be calculated from the 13C‐NMR spectra is the mean alkyl chain length.

In this study a number of commercially available sulphonate and phenate detergents have been investigated. For the sulphonates the alkyl chain length was found to range from 17–22 carbon atoms, and for the phenates the alkyl chain length proved to be approximately 9–12 carbon atoms. The phenate alkyl chains showed significantly more branching than those in the sulphonates.

In the 1H‐NMR spectra, the position of the acidic proton signals is influenced by the measurement temperature, water concentration and solvent. The effect of these parameters was studied in detail.

A combination of sample preparation techniques, such as dialysis, and hydrolysis and spectroscopic techniques, such as IR and NMR, can be used successfully to characterise detergents in terms of their molecular structure.
Friction characteristics of piston rings in a reciprocating engine
Authors: Hamatake T. , Kitahara T. , Wakuri Y. , Soejima M.
Published: July 2006

The performance of a reciprocating engine can be improved by reducing the friction between piston rings and cylinder liner, which significantly contributes to the mechanical friction losses of an engine.

The friction force of a piston ring pack is calculated, based on hydrodynamic lubrication theory, for the piston rings. Calculations were carried out for three sets of conditions. Oil starvation is taken into consideration in the calculation of oil‐film behaviour for a ring pack. The friction characteristics of piston rings are evaluated using the frictional mean effective pressure.

The friction force of a piston assembly is measured experimentally by an improved floating liner method. The effects of lubricant viscosity and engine speed on friction characteristics are investigated by both calculation and experiment.