bluuebunny/crossref_metadata_2025 huggingface dataset:
Antiwear synergism of borates and cadmium diamyldithiocarbamate
Authors: Junbin Yao
Published: July 2006

Certain combinations of an oil‐soluble cadmium compound, e.g., cadmium diamyldithiocarbamate, with organo‐borates, either sulphurised or nonsulphurised, give better antiwear performance than do the individual components. A synergistic mechanism is postulated, in which boron atoms with vacant p orbitals catalyse triboreduction of cadmium on rubbing surfaces, producing elemental cadmium. The cadmium deposits on, and alloys with, the metal surface to protect the substrate against wear.
Friction and wear behaviour of liquid paraffin containing an S‐P type additive and amine
Authors: Weimin Liu , Canzhu Gao , Pingyu Zhang , Qunji Xue
Published: July 2006

Sulphurised olefin (SO) and dibutyl phosphite (DBP) are two popular antiwear and extreme‐pressure additives for gear oils. Investigation of the effects of the weight ratio of SO to DBP in liquid paraffin, and the effects of dodecyl amine, on the friction and antiwear properties of oil, were conducted with a four‐ball wear tester. The chemical composition of the film, formed was examined using X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and reflecting infrared spectro‐scopic (IR) microscopy.

The four‐ball test results indicate that the weight ratio of SO to DBP affects the friction and wear behaviour of the oil and, with a weight ratio of SO to DBP of 20:1, a stable friction coefficient, and the smallest wear scar, were observed. Wear tests also showed that dodecyl amine improves or reduces the antiwear ability of the oil at certain concentrations. AES profile analyses demonstrate a thick boundary film formed on the rubbed surface with the weight ratio of SO to DBP at 20:1. Both AES and IR results indicate that the addition of dodecyl amine to an S‐P type oil results in competitive adsorption, and hinders the reaction of SO and DBP with the steel surfaces.
Expressions for coefficients of electrorheological fluid dampers
Authors: Kohl James G. , Tichy John A.
Published: July 2006

Useful expressions are developed for the damping coefficient of two types of viscous dampers that contain electrorheological (ER) fluids. The damping action in the first type occurs in flow between stationary parallel plates; the second type has annular flow between two stationary concentric cylinders. For ER fluid control, an electric field is applied across the gap in which the fluid flow occurs. The solution for the concentric cylinder damper is based on a thin gap approximation. These solutions may facilitate solving mechanical systems problems, using ER fluids, and demonstrate the controllability of ER dampers.
The tribological properties of diethylammonium lanthanide tetrakis (diethyldithiocarbamate) in lubricating oil
Authors: Zefu Zhang , Weimin Liu , Qunji Xue , Tianhui Ren , Wei Wang
Published: July 2006

The synthesis of four oil‐soluble rare earth complexes of diethylammonium lanthanide tetrakis(diethyldithiocarbamate) (ReDTC) is described. The tribological properties of these rare earth complexes as additives in lubricating oil have been evaluated using a four‐ball machine. The results show that these novel complexes have excellent extreme‐pressure properties and selective antiwear properties in lubricating oil. The action mechanism of the rare earth complexes as additives in lubricating oil was investigated using X‐ray photoelectron spectroscopy (XPS).
Friction and wear of grey cast iron against Si3N4 in emulsion and water
Authors: Liang Fang , Songhua Si , Yimin Gao , Qingde Zhou
Published: July 2006

Friction and wear tests of Si3N4 against cast iron were carried out using a ring‐on‐block tester lubricated by emulsion. To provide a comparison with emulsion, distilled water was also used as a lubricant in the tests. The results show that emulsion can prevent the formation of an SiO2·2H2O film on the iron surface. Although the friction coefficient of Si3N4/ iron pairs in emulsion is much greater than in distilled water, the wear of Si3N4 in emulsion is less.
Hydrodynamic lubrication of the ironing process
Authors: Mahdavian S. M. , He D.
Published: July 2006

A theoretical model is presented to calculate the lubricant film thickness in an unsteady hydrodynamic lubrication of cup‐shaped products to be formed by the ironing process. The model covers the development of hydrodynamic lubrication in various phases of the ironing process. The model provides equations for estimating the lubricant film thickness for each phase.

Experiments were conducted to study the effect of lubricant viscosity on die expansion and punch force in making cup‐shaped products by the ironing process. It was found that the die expansion varied between unlubricated and lubricated cups and depended on the lubricant viscosity. The film thickness was estimated from the difference between the increased die/punch clearance, which was calculated from the expansion, and the lubricated cup wall thickness. The theoretical film thickness was compared with the estimated film thickness based on the die expansion measurement.
Evaluation of surface fatigue performance of gear oils
Authors: Hong H.‐S. , Huston M. E. , O'Connor B. M. , Stadnyk N. M.
Published: July 2006

The effect of additive chemistry on the surface fatigue of gears was investigated using an FZG gear tester and fluids based on an API GL‐5 grade gear oil. Surface fatigue lives were determined as a function of load and additive chemistry. At 1.52 GPa, the removal of the primary extreme pressure (EP) additive from the fully formulated gear oil decreased the fatigue life of gears slightly (4%). However, the removal of the primary antiwear (AW) additive decreased the fatigue life of gears significantly (83%). At 1.86 GPa, the removal of the EP additive from the fully formulated gear oil decreased the gear fatigue life by 27%. However, the removal of the primary AW additive decreased the fatigue life of gears significantly (75%). Micro‐pitting was the dominant surface morphology in the dedendum of the gears tested with two oils at load stage eleven: one using the complete additive package, and a second where the EP additive had been removed. However, spalling was the primary failure mode of gears tested without an AW additive, independent of whether an EP agent was present. Surface analysis of the pinion gears showed the formation of a mixed phosphate/phosphite—oxide layer on the surface of gears tested with fluids containing an AW additive. Formation of this layer seems to be the key to a long fatigue life.
Friction and wear behaviour of an Al‐Si alloy against steel lubricated with N‐ and O‐containing organic compounds
Authors: Weimin Liu , Yanhong Hu , Zhiming He , Pingyu Zhang , Qunji Xue
Published: July 2006

The friction and wear properties of an Al‐Si alloy against AISI 52100 steel were investigated with a block‐on‐ring wear tester lubricated with a liquid paraffin base oil containing organic additive compounds, such as ethylenediamine, ethyleneglycol, ethanolamine, and N,N‐dibutylethanolamine. The boundary film formed on the rubbed surface of the Al‐Si alloy was then examined using FT‐IR microscopy and XPS.

The friction and wear tests revealed that ethylenediamine, ethanolamine and N,N‐dibutylethanolamine additives provide good lubrication in the Al‐Si alloy‐on‐steel system, especially N,N‐dibutylethanolamine. FT‐IR microscopy and XPS revealed the possible formation of a chemically stable five‐ring complex of aluminium or silicon with diamine and ethanolamine.
Variation and recovery of resistivity of industrial greases — an experimental investigation
Authors: Prashad Har
Published: July 2006

In the present work, variation in the resistivity of different greases with time in static conditions, under the influence of applied potential drops, is established. The change in resistivity and physico‐chemical characteristics of the greases in electric fields, and recovery of the resistivity within the test period in the absence of applied potential drop, have been found.

The properties of the greases are compared, and their correlation with resistivity is analysed.

The paper also gives the results of analysis using an SRV tester, IR spectra, chemical analysis and spectrophotometry, of changes that occurred periodically in the greases, normally used in non‐insulated rolling‐element bearings in the presence of a potential drop across the inner and outer races. The paper highlights the behaviour and mechanism of the process of bearing failure under electric fields.
Highly reactive polyisobutene as a component of a new generation of lubricant and fuel additives
Authors: Mach H. , Rath P.
Published: July 2006

This paper describes the synthesis of highly reactive polyisobutene (PIB), a special type of PIB used as a component in the production of lubricant and fuel additives. The reactivity and the chemical structure are described in detail, in relation to the nature of the product and its uses as an additive component.
Synthesis of new additives for lubricating oils and industrial greases
Authors: Dinoiu Vasile , Florescu Danilian , Stanescu Chiriaca
Published: July 2006

Ashless antiwear, antioxidant, and extreme‐pressure additives based on hydrocarbon‐soluble metallic complexes of thio‐bis‐phenols, their method of preparation, and their use as additives in oils and industrial greases, have been studied. This paper presents a description of their derivation and performance.
A simplified calculus method for a grease‐lubricated Rayleigh step bearing
Authors: Radulescu A. V. , Vasiliu F.
Published: July 2006

The paper presents a simplified method for the analytical calculus of a grease‐lubricated infinitely large Rayleigh step bearing.

The principal problem of the grease flow through a Rayleigh step bearing is the shape of the stagnant core in the step region. This shape is determined using Navier‐Stokes equations resolved by the finite method element. The theoretical results are compared with those obtained experimentally by visualisation of the grease flow using the reflecting tracer method. The conclusion of the simplified method is that a Rayleigh step bearing lubricated with grease is equivalent to one lubricated with oil, but with a different configuration of the convergent interstice.
Low‐temperature rheology of engine lubricants subjected to mechanical shear: Viscosity modifier effects
Authors: Covitch Michael J. , Weiss Joseph , Kreutzer Ingo M.
Published: July 2006

It is well known1–5 that the viscosity of crankcase lubricants decreases in the early stages of use due to shearing of the viscosity modifier (VM) and, depending upon the type of service, fuel dilution. This paper examines the effects of VM chemistry on the shearing process, and particularly how both high‐temperature and low‐temperature viscosities can change as a result of mechanical shear in the Kurt Orbahn injector test and during a passenger car fleet test. Commercial olefin copolymer, styrene/butadiene, styrene/isoprene, and radial isoprene polymers were included in this study, as a way of representing the major VM chemistries used in motor oils throughout the world. The rate of change of kinematic and high‐temperature, high‐shear‐rate viscosity with time, as well as low‐temperature cranking and pumping viscosity changes, were found to be characteristic of particular VM chemistries.
The preparation and tribology of spherical nanometric particles of diantimony trioxide SbOx(OH)y
Authors: Dong J. X. , Hu Z. S. , Chen G. X.
Published: July 2006

Spherical diantimony trioxide SbOx(OH)y with a particle size of 30–70 nm has been prepared using a technique known as ‘ethanol supercritical fluid drying’. The tribological properties of an SN500 oil containing these nanometric particles were measured using a four‐ball and block‐on‐ring tribotester. The wear resistance and load‐carrying capacity of the oil were higher, and its friction coefficient lower, than that of the base oil. An excessive nanometric particles content was found to be disadvantageous to the load‐carrying capacity of the oil. The spherical nanometric diantimony trioxide appears to work by deposition on the rubbing surfaces and through the rolling action of the spherical particles.
The effect of viscosity index improvers on the determination of metal content in new and used multigrade oils
Authors: Mohamed M. M. , El Naga H. H. Abou , El Meneir M. F.
Published: July 2006

Atomic absorption spectroscopy is widely used to determine the metal content, especially of zinc, calcium, iron, and copper, in new and used multigrade oils. Many methods involve dilution of the sample with kerosene followed by aspiration into the atomic absorption. However, results indicate that such methods are subject to matrix interferences, the factors most influencing such interferences being: the concentration of viscosity index improver incorporated into the multigrade oil formulations; chemical structure of the viscosity index improver; the molecular weight of the viscosity index improvers; and the viscosity of the solvent used.

Regression equations for some commercial viscosity index improvers have been established, to permit correction of the concentrations of zinc, calcium, iron and copper measured in new and used multigrade oils.
The influence of chemical composition on the pour‐point depressant properties of methacrylate copolymers used as additives for lubricating oils
Authors: Florea M. , Catrinoiu Doina , Luca Paul , Balliu S.
Published: July 2006

Methacrylate polymers are much used as additives in lubricating oils, as pour‐point depressants and viscosity index improvers. Although the mechanism of such pour‐point depression is still controversial, it is thought to be related to the length of the alkyl side chains of the polymethacrylates, and to the nature of the base oil. In this paper, work is reported on: (a) the depressant activity of polymethacrylate copolymers in relation to the content of short alkyl methacrylates and styrene, and the average side‐chain length of the basic methacrylate constituents; (b) the pour point of the base stock; and (c) the additive concentration.
Maximum oil film pressure and temperature of two‐iobe journal bearings with different bush profiles
Authors: Strzelecki Stanisław
Published: July 2006

This paper presents data on the maximum oil film pressure and temperature of two‐lobe journal bearings with different bore profiles. A bearing with a cylindrical non‐continuous bore profile, and another with a pericycloid continuous profile have been evaluated. For an assumed relative length of the bearings, and parallel orientation of the journal and bearing axes, the minimum values of oil film thickness, maximum pressure values, and temperatures of the oil film have been determined. The calculations were carried out on the assumption of an adiabatic oil film and a static equilibrium position of the journal.
Synthesis of some additives from upgraded petroleum residues of lubricant oil refineries
Authors: Mohamed M. M. , Naga H. H. Abou El , Anis A.
Published: July 2006

Aromatic extract residues occur as by‐products in petroleum refineries, through the process of refining lubricant oil. These residues are considered as having low economic value, and their disposal may even cause problems for the refineries. The present work looks at upgrading these residues by using them to synthesise different petroleum additives, e.g., antioxidants, ashless dispersants, pour‐point depressants, and flow improvers for lubricating crankcase oils and for fuels. The antioxidants were synthesised by reacting mono‐aromatics with phosphorus pentasulphide (P2S5) in the presence of zinc oxide (ZnO). Ashless dispersant additives were synthesised by reacting alkylated mono‐aromatics (using chlorinated paraffin wax as an alkylating agent) with formaldehyde solution (37%) in the presence of polyisobutylene succinimide. Fuel pour‐point depressants and flow improvers can be synthesised by acylating di‐aromatics via a Friedel‐Crafts reaction. Comparative evaluation of the synthesised products with commercial additives showed them to have good comparative performance properties.
The effect of mechanical stress on four viscosity improver polymers
Authors: Bezot P. , Hesse‐Bezot C. , Faure D. , Calvez J. C.
Published: July 2006

The effect of a Bosch injector on the mass distribution function of four viscosity improver (VI) polymers has been studied. Two of these, hydrogenated styrene—isoprene (HSI) and hydrogenated styrene—butadiene (HSB), are di‐block polymers, whereas the others are either comb‐like, polyalkyl methacrylate (PMA), or linear, olefin copolymer (OCP).

Measurements were performed by light scattering and viscometric techniques before and after application of mechanical stress. Only slight modifications in the physical properties were detected for HSB and HSI, which can be explained by their micellar behaviour. Conversely, a large variation in mean size and viscometric properties was observed for PMA and OCP. Finally, a model is proposed which links the variation of the mass distribution function to the intrinsic viscosity loss.
A comparative study of the thermal behaviour of circular and non‐circular journal bearings
Authors: Sehgal Rakesh , Swamy K. N. S. , Athre K. , Biswas S.
Published: July 2006

A comparative theoretical analysis of three types of hydrodynamic journal bearing configuration, namely, circular, axial groove, and off‐set halves, is presented for the thermohydro‐dynamic case. The two‐dimensional solutions of the Reynolds and energy equations take account of the variation in lubricant viscosity with temperature. The theoretical models also consider heat conduction through the bush, but do not take account of heat transfer through the shaft or recirculation of oil. It is observed that the off‐set bearing runs cooler than an equivalent circular bearing with axial grooves.
Viscometric studies of oil‐in‐water mixtures
Authors: Nabhan M. B.
Published: July 2006

An interesting property of oil‐in‐water (o/w) mixtures that has attracted the attention of tribologists, is their ability to form thicker hydrodynamic films than those expected from their apparent rheological properties. In concentrated contacts lubricated with o/w mixtures the oil phase is believed to separate out on the metal surface.

To study this phenomenon, experiments have been conducted on a specially designed viscometer rig, with different concentrations of o/w mixtures used as a lubricant. The rig was composed of a metal tube with a straight and parallel cylindrically ground bore and metal ‘droppers’ of similar tolerances. The droppers can descend in the tube filled with the o/w mixture at a uniform velocity; the radial clearances between the descending droppers and the tube are very small.

It was found that, even at oil concentrations as low as a few per cent, higher viscosity values for o/w mixtures are obtained in concentrated contacts, in relation to their bulk values. These results can be quantitatively explained in a theory which assumes trapping of oil particles between metal surfaces, correlated to the displacement energy at the oil—water—metal boundaries.
A study of the purification of used engine oils with a montmorillonitic clay
Authors: Mohellebi F. , Bouchekhou A. , Harbi N. , Hadjoudj F. T. , Chitour C. E.
Published: July 2006

The present paper looks at percolation, a recycling technique for engine oils that is non‐polluting and dispenses with the use of acid. The technique employs Algerian bentonite as a complementary purifier of used SAE 20W–50 engine oils which have first been dehydrated and had the light hydrocarbons (gasoline) removed. In order to understand the nature of the used oil, the characteristics of an oil in service were closely monitored over 7000 km. Various tests were performed on the bentonite to find the most satisfactory form of clay filtration bed. The species retained by the beds were analysed.
Manufacture of a transformer oil from egyptian paraffinic base stocks via a hydrogenation process
Authors: Abou H. H. , Naga El , El Ashry E. S. H. , Khattab M. A. , Salem A. E. , Boghdady Y. M.
Published: July 2006

This paper describes work aimed at producing a high‐quality transformer oil from local Egyptian paraffinic base stock by hydrogenation, or hydrogenation plus sulphonation.

Analysis showed that the neutral base oil 70N was suitable for producing transformer oil. This neutral base oil was chemically treated by hydrogenation under various conditions of temperature, pressure, and time, using two different catalysts, and by hydrogenation followed by sulphonation using optimum conditions. Optimum hydrogenation conditions were achieved by using a Ni/Mo (10 wt. %) catalyst, at 275°C and 100 psi pressure for 60 min, while optimum sulphonation conditions were achieved in previous work by using oleum or SO3 gas at a concentration of 6 wt. % at 35°C for 60 min.

Laboratory results and field trials indicated that the neutral paraffinic base oil when so treated meets the IEC 296 international specification for transformer oil, with the exception of the pour point (−18°C). However, this pour point is not relevant in certain hot climatic conditions. Evaluation of the treated oil with commercial transformer oil has shown its potential for use.
Technical note: Extreme‐pressure activity assessment of certain nitrogen and sulphur compounds in lithium‐based grease
Authors: Singh T. , Bhan A. K.
Published: July 2006

In this paper we report on the preparation and extreme‐pressure (EP) activity assessment of certain substituted 1‐amino‐3‐aryl‐2,3‐dihydro‐2‐thioxo‐4,6‐(1H,5H)‐pyrimidinediones as additives in a lithium‐based grease. These additives significantly decreased the wear and friction and possessed the ability to increase load‐carrying capacities and weld loads. Two greases were prepared with the above additives, and both greases exhibited lower values of wear‐scar diameter at higher loads and higher values of weld load in the four‐ball test than the lithium‐based grease alone. The prepared greases also passed rust and corrosion, and oxidation tests.
Boundary lubrication of low‐sulphur diesel fuel in the presence of fatty acids
Authors: Kajdas C. , Majzner M.
Published: July 2006

This paper presents an overview of the effect of aliphatic acids on the tribological properties of selected hydrocarbons and petroleum fractions. The major experimental part of the work focuses on improvements to the lubricity of low‐sulphur diesel fuel. Experiments were carried out using a pin‐on‐disc friction machine and HFRR test rig. The wear results obtained clearly show a specific effect of the test acids dissolved in hydrocarbons in the concentration range 0.005–0.1% (50–1000 ppm). Although the overall picture presented by these results is very complex, it can be concluded that a very small amount of the selected acids dramatically improves low‐sulphur diesel fuel lubricity.
Recovery of residual emulsifiable oil from waste water by flotation
Authors: Omar A. M. A. , Mohamed Mamdouh S. , Ibrahim Hoda
Published: July 2006

A source of waste‐water pollution in machining is the lubricating/cooling fluid used. This study investigates the application of the flotation technique for the removal of emulsifiable oil. Research has been carried out on a process of selective separation of oil using mixtures of anionic/nonionic surfactants as collectors and a cationic surfactant as a de‐emulsifier (coagulant). The behaviour of the mixtures at the aqueous solution‐air interface has been studied, and the critical micelle concentration, efficiency, effectiveness, minimum surface area, and free energy of micellisation determined. The effect of the optimum mole fraction of the mixtures on oil separation has been discussed from the point of view of physical parameters. The selectivity achieved can be explained in terms of surfactant concentration and the structure of the micelles.
Possibility of slip in hydrodynamic oil films under sliding contact conditions
Authors: Ono B. , Yamamoto Y.
Published: July 2006

In hydrodynamic lubrication theory, the oil film thickness build‐up increases with increasing sliding speed or oil viscosity, and the viscous resistance or shear stress also increases, both without limit. The entraining force forming the oil film is given by the moving surfaces, or by the adhesive force of the oil molecules on the rubbing surfaces and the interaction force between them. Therefore, the maximum friction force and maximum oil film thickness will be limited by the operating conditions, such as oil properties, rubbing materials, sliding speed, and load. In this study, friction tests were conducted using a plate‐on‐cylinder sliding contact apparatus. It was found that a critical shear stress existed, above which the friction force and oil thickness decreased from theoretical values. Slip in an oil film seems to occur when the theoretical shear stress exceeds the critical value of the oil, according to test conditions. The occurrence of slip in an oil film is responsible for the reduction in the oil film and friction force from theoretical values, leading to the lower‐viscosity components of the oil selectively passing through the conjunction zone.
Frictional behaviour of Pb‐Sn thin‐film lubrication
Authors: Uemura Masao
Published: July 2006

The frictional properties of lead‐tin thin films (thickness of 0.05–0.19 μm) with two types of copper interlayer were investigated. The thin film and the interlayer were formed on a silicon wafer surface by vacuum deposition. Friction tests were carried out using a ball‐on‐disc apparatus in a vacuum chamber. The thin copper interlayer reduced the friction coefficient and prolonged the film life. The effect of load on the friction coefficient is explained by an equation derived using the Hertzian contact area between a sphere and a plate. The thicker copper interlayer did not reduce the friction coefficient but markedly extended the life of the film. In this case, the dependence of the friction coefficient on the load is explained by an equation derived using the Hertzian contact area between a sphere with surface roughness of second order and a plate.
Engine oil ageing under laboratory conditions
Authors: Vipper A. B. , Zadko I. I. , Ermolaev M. V. , Oleinik J. Y.
Published: July 2006

In recent years the role of laboratory methods in investigating the effectiveness of engine oil additives has dramatically increased, especially in predicting the performance of engine oils under field conditions. Some results of research under laboratory conditions on the ageing of engine oils with different performance levels are presented in this paper. The role of the action of antioxidant additives in engine oils for gasoline and diesel engines is described. The paper includes the results of experiments over time in laboratory testing of doped motor oils, use of IR spectroscopy, and reference oils. Single‐ and multi‐cylinder engine test results are also discussed. New, effective additive packages for different engine oils are considered.
Lubrication of a narrow porous journal bearing with a couple stress fluid
Authors: Naduvinamani N. B. , Hiremath P. S. , Fathima Syeda Tasneem
Published: July 2006

This paper describes a theoretical investigation of the rheological effects of couple stress fluids on the performance of narrow porous journal bearings. A most general modified Reynolds equation is derived for narrow porous journal bearings using the Stokes constitutive equations for couple stress fluids. The fluid in the film region and in the porous region has been modelled as a couple stress fluid. The analysis takes into account velocity slip at the porous interface using the Beavers‐Joseph criterion. A closed‐form expression for field pressure is obtained for narrow journal bearings. Eigen‐type expressions for field variations are obtained. The dimensionless load‐carrying capacity, attitude angle, and coefficient of friction are presented for different operating parameters. It is observed that narrow porous journal bearings with couple stress fluids as lubricant show a significant increase in load‐carrying capacity with reduced coefficient of friction as compared to the Newtonian case. The present study predicts the effects of the percolation of polar additives (microstructures) into the porous matrix on the bearing performance.
Designing automotive gear oils for the new millennium
Authors: Hong Hyun‐Soo
Published: July 2006

New engine design changes and ever‐increasing engine requirements make the design of gear oils challenging. A proper understanding of fundamental lubrication theory and formulation knowledge is necessary to develop new gear oils. This paper provides an overview of the fundamentals of lubrication theory and the functions of each additive. Key technical issues facing gear oils are also discussed.
Electrical resistivity and conductivity of greases: An initial study
Authors: Eriksson Erland , Nygård Sven , Lundberg Jan
Published: July 2006

Investigations of railway wagons fitted with rolling‐element bearings have shown damage to the bearings from the passage of electric current. This also occurs in railway wagons without an electric energy consumption of their own, because of residual currents from electric locomotives. This phenomenon gives rise to technical, financial, and even safety problems. This paper reviews research in the field of rolling‐element bearings exposed to electric currents. The paper also reports on an ongoing study undertaken to understand the mechanism of current flow and the role of lubricants in the associated damage, and to identify the possibilities of minimising bearing damage. The obvious solution to this problem is to use optimised greases, i.e., with high electrical conductivity and good lubricating ability.

In the preliminary work reported here a number of greases for railway use were tested to determine their electrical conductivity in static and dynamic situations. These tests were performed using specially designed apparatus, and significant initial information about the electrical properties of greases has been obtained in this research, for example, that there is a correlation between the electrical conductance under static and dynamic conditions. All the greases tested showed comparatively high resistivity values, which could be one explanation for the bearing damage observed.
Applications of the concept of tribopolymerisation in fuels, lubricants, metalworking, and ‘minimalist’ lubrication
Authors: Furey M. J. , Kajdas C. , Kempinski R.
Published: July 2006

Tribopolymerisation, a novel concept of molecular design developed by Furey and Kajdas, involves the continuous formation of thin polymeric films on rubbing surfaces; the protective films formed are self‐replenishing. The antiwear compounds developed are effective with metals and ceramics and in the liquid and vapour phases. Furthermore, they are ashless and contain no harmful phosphorus or sulphur, and many are biodegradable. The potential applications are diverse and have cost, performance, energy, and environmental advantages.

The present paper describes some applications of the concept of tribopolymerisation as a mechanism of boundary lubrication, including recent laboratory research and in‐plant industrial demonstrations. Applications include: (a) ashless antiwear or ‘lubricity’ additives for fuels; (b) ashless lubricants for automotive engines to reduce exhaust catalyst poisoning and environmental emissions; (c) lubrication of ceramic engines or ceramic components; (d) machining and cutting using thin films to reduce friction and ceramic tool wear; (e) vapour‐phase applications in high‐temperature gaseous systems or to counter fuel injector wear problems in natural gas engines; (f) special ‘minimalist’ pre‐treatment compositions for engine assembly and running‐in; and (g) enabling technology in the development of new engines and propulsion systems.
Temperature characteristics of the boundary lubricating film of an organocopper compound
Authors: Jianhua Zhang , Changqin Feng , Yuan Zhao
Published: July 2006

The relationship between the temperature and the lubricating properties of an organocopper compound used as a lubricant additive has been studied on steel‐steel rubbing pairs. The results showed that the organocopper compound significantly reduced both the wear and the friction of steel balls for different test temperatures, but that there is a distinction between the friction critical temperature and the wear critical temperature. Results showed that the organocopper additive could improve both the friction critical and the wear critical temperature of a mineral oil. For example, the friction critical temperature increased from 50 to 220°C and the wear critical temperature from 110 to 290°C. Micrographs of the wear scars at different temperatures were used to investigate the lubricating film's temperature characteristics.
Soot characterisation and diesel engine wear
Authors: Jao T.‐C. , Li S. , Yatsunami Kenji , Chen Shiahn J. , Csontos Aladar A. , Howe James M.
Published: July 2006

The hardness of various types of soot produced by heavy‐ and light‐duty diesel engines of European, Japanese, and North American designs was measured by low‐loss electron energy‐loss spectroscopy (EELS). No clear general trend can be established that shows heavy‐duty diesel engine soot is necessarily harder than light‐duty diesel engine soot. The variation in hardness among individual soot particles produced by the same diesel engine can be as large as differences between the hardest soot particles produced by heavy‐duty diesel engines and the softest soot particles produced by light‐duty diesel engines. There are heavy‐duty diesel engines that can produce soot that is softer than that produced by some light‐duty diesel engines and vice versa. Nevertheless, the hardness of all types of soot studied is close to the range of hardness of metal engine parts. Thus, the results indicate that soot is hard enough to abrade some metal engine parts.
MoS2‐based alloys and nanocomposites for solid lubrication
Authors: Savan A. , Haefke H.
Published: July 2006

The development of MoS2 coatings has involved the modification of substrate surfaces, the addition of metals or compounds to the MoS2, and variation in the deposition process parameters affecting the properties of deposited films. More recently, multilayer and periodic nanolayer coating structures have also been investigated. At present, work is concentrated on alloys of MoS2, mainly with various metals, and targeted at terrestrial (ambient air) applications.

The addition of metals or compounds to physical‐vapour‐deposited MoS2 has led to improvements in coating performance, for example, greater stability of friction coefficient, greater film endurance, and increased temperature/oxidation resistance. The metal or compound can be either in the form of nanoscale multilayers or mixed with the MoS2, sometimes leading to nanoclusters within a MoS2 matrix. Microstructural analysis seems to show that the primary function of these additives is to suppress the formation of low‐density, columnar structures. At certain concentrations an added metal can also enhance the formation of the tribologically favourable (002) orientation of the MoS2 crystallites. Other changes in the properties of MoS2—metal composites may be due to their oxidation resistance, as indicated by the stability of these films against storage in air and their increased endurance when in sliding contacts at elevated temperatures.
Lubricating properties of thixotropic systems based on overbased calcium sulphonate
Authors: Kobylyansky E. V. , Mishchuk O. A. , Ishchuk Yu. L.
Published: July 2006

The lubricating properties of model systems based on overbased calcium sulphonate have been studied by simulating various kinematic, temperature, and load‐speed conditions of friction machines as well as by investigating the physical chemistry of friction surfaces. It is found that overbased sulphonate complex grease shows good antifriction, antiwear, and extreme‐pressure properties. A synergistic action of calcium tetraborate with overbased sulphonate has been shown. It is found that calcium 12‐hydroxystearate, however, has little effect on lubricating properties, but it improves the thixotropic characteristics of a system.
Molecular dynamics studies of a lubricant system by NMR spectroscopic techniques
Authors: Sarpal A. S. , Sastry M. I. S. , Kapur G. S. , Bansal V. , Mehta A. K. , Bhatnagar A. K.
Published: July 2006

The present studies highlight the applications of NMR spectroscopic techniques for unravelling the unique structural features present in base oils responsible for imparting lubricant properties. The viscosity—temperature and viscosity—pressure properties of base oils of API groups I—IV, such as viscosity, viscosity index, pour point, elastohydrodynamic film thickness, and pressure—viscosity coefficient, have been correlated with the detailed hydrocarbon composition of base oils with an emphasis on the various types of methyl branched structures. Molecular dynamics parameters, such as diffusion coefficient and energy of activation, estimated from the NMR spectral studies have provided evidence of the factors responsible for the different viscosity—temperature or viscosity—pressure characteristics of base oils.
Lubricant oils additivated with polymers in EHD contacts: Part 2. Tests using a four‐ball machine
Authors: Paleu V. , Bercea I. , Cretu S. , Bercea M.
Published: July 2006

A mineral oil of low viscosity was additivated with different concentrations of low‐density polyethylene. The wear behaviour of the additivated samples and the base oil was evaluated using a four‐ball wear tester at constant speed and variable load. Steel and ceramic (silicon nitride) were chosen for the balls. The scuffing resistance of the ceramic balls was higher than that of the steel balls. No scuffing appeared in the case of an upper steel ball in contact with lower ceramic balls. As far as the minimum wear‐scar diameter on the lower balls was concerned, an optimum concentration of polymer added to the base oil was found from the experimental data, for both types of ball. For the systems investigated, the optimum concentration was about 1.0% polyethylene.
Lung contusion from focal low‐moderate chest trauma
Authors: Hafen G.M. , Massie J.
Published: July 2006

Apparently minor chest trauma may result in localized pulmonary contusion. Complications of the contusion, particularly infection, may be delayed. The association between the infection and initial injury may not be appreciated due to the time frame between the injury and clinical presentation. We report two cases of low‐moderate impact pulmonary trauma resulting in focal pulmonary contusion, complicated by infection. Pediatr Pulmonol. 2006, 41:1005–1007. © 2006 Wiley‐Liss, Inc.
Health‐related quality of life of pre‐school children with wheezing illness
Authors: Oostenbrink R. , Jansingh‐Piepers E.M. , Raat H. , Nuijsink M. , Landgraf J.M. , Essink‐Bot M.L. , Moll H.A.
Published: July 2006

Pre‐school children are frequently affected by wheezing illness, with substantial influences on their health‐related quality of life (HRQL). The Infant/Toddler Quality of Life Questionnaire (ITQOL) is the only generic health status measure for children aged 2 months up to 5 years. In this present study we evaluated the impact of wheezing illness in pre‐school children on the HRQL, using the ITQOL. A questionnaire including the ITQOL and ISAAC questions on frequency and severity of respiratory complaints were sent to parents of patients aged 6 months–5 years visiting the outpatient department with wheezing illness. Scale scores of ITQOL of the included children were compared with general population scores. Using multivariate analysis, the influence of general and clinical characteristics on ITQOL scale scores was evaluated. Results are based on 138 children, 59% male, mean age 34 months. Children with wheezing illness scored differently to the general population sample on 8 of the 11 ITQOL scales. Age, comorbidity and employment of the respondent affected scales on child's physical and emotional functioning and parental functioning. Severity of dyspnoea and wheezing, presence of cough, corticosteroid use, and number of GP visits negatively affected scales on the child's physical and emotional functioning. In conclusion, the HRQL as measured by the ITQOL was lower in a group of Dutch pre‐school children with wheezing illness compared to a general population sample. The scale scores were sensitive to age, co morbidity, socio‐economic situation, and disease severity. Pediatr Pulmonol. 2006, 41:993–1000. © 2006 Wiley‐Liss, Inc.
History of the loss prevention symposia: Forty years, 1967–2006
Authors: Davenport John A.
Published: July 2006

In the early 1960s a number of sizable explosions and fires occurred in the oil and petrochemical industries. A light hydrocarbons plant in Louisiana suffered a vapor cloud explosion. This phenomenon, although it had occurred before, was largely unrecognized in industry. At about the same time, the process industries were moving toward the “jumbo” plants. Formerly, ammonia was produced in multiple plants of 100 to 300 tons/day capacity with multiple parallel lines of reciprocating compressors. However, in the early 1960s ammonia plants having capacities of 750, 1000, and 1500 tons/day with centrifugal machines were rolling off the designers boards. Large, single‐train olefin plants, with capacities of 1.5 billion pounds per year, were also being designed and erected.

As a response to these trends, a number of people from industry and insurance put together a symposium to explore ways to improve loss prevention in the process industries. This symposium contained six sessions and was held at the AIChE National meeting in Houston in 1967. Attendance was excellent and a committee was formed to prepare annual symposia on the topic. These symposia are still held at AIChE National meetings with the 40th Loss Prevention Symposium being held this year. This paper will discuss some of the highlights of these symposia and some of the people that have made them so successful over the years. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006
Thermal conductivity of superfluid B phase 3He in aerogel
Authors: Shahzamanian M. A. , Yavary H.
Published: July 2006

We calculate the thermal conductivity of normal and superfluid 3He impregnated into high‐porosity aerogel by using Kubo formula approach. The thermal conductivity exhibits cross‐over behavior from the high temperature regime, where inelastic quasiparticle‐quasiparticle scattering dominates, to low temperature regim dominated by elastic scattering of quasiparticles off the aerogel. In addition to the relaxation time due to quasiparticl‐quaiparticl interaction (τ int) we include the relaxation time due to collision with aerogel strands (τ imp). By calculating approprate self‐energies these two relaxation times are evaluated. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The BM5Se9 phases: studies of the behaviour of superconductors and ferromagnets
Authors: Leblanc‐Soreau A. , Molinié P. , Jumas J.C.
Published: July 2006

Syntheses performed in the A3B/MSe2 systems lead to the formation of (B/B′)(M/A)5Se9 phases (ferromagnets or superconductors) {A = M = (Nb, V, Ta); B = B′ = (Al, Ge, Ga, Sn, Sb)}. The magnetic studies on GaV5Se9, GaV0.15Ta4.85Se9 and Sn0.94Ga0.05V0.30Nb4.70Se9, compared to that of SnNb5Se9, GaNb5Se9 show that the presence of V modifies the superconducting exchanges and allows ferromagnetic couplings. Through Point‐Contact Spectroscopy on SnNb5Se9, it is shown that nanoclusters of the pristine NbSe2 and Nb3Sn exist, so the properties result from a synergy between them and the matrix, and it could be a mesoscopic superconductor. The superconductors's Tc values vary from 17.5(2) K for SnNb5Se9 to 6.0(2) K for SbNb5Se9, and the ferromagnetic state transition from 22K for GaV5Se9, to 35 K for Sn0.94Ga0.05V0.30Nb4.70Se9. The 119Sn and 121Sb Mössbauer studies of Sn0.94Ga0.05V0.30Nb4.70Se9 and SbNb5Se9 are compared to that obtained for SnNb5Se9 itself; for this last one, 3 types of sites corresponding to 2 species of Sn were observed with a reversible dynamic process between the 2 SnII Sn‐Se sites correlated to a modification of the Sn‐Nb site(1). SbNb5Se9, at 5 K, shows just a singlet, attributed to Sb surrounded by Se; from 298 K to 5 K, Sn0.94Ga0.05V0.30Nb4.70Se9, presents one asymmetrical Sn‐Se site without any transferred field on Sn and an increased asymmetry when T decreases. Sn0.94Ga0.05V0.30Nb4.70Se9 is a weak and complicated ferromagnet. In both cases, GaV5Se9, and Sn0.94Ga0.05V0.30Nb4.70Se9, the ESR spectrum observed at 300 K can be fitted with 2 lorentzian distributions: for the first case, with axial symmetries, for the second only one remains with an axial symmetry, belonging to the V sites. its vanadium sites are thus less symmetrical than in the first case. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The dependence of the properties of YBa2Cu3O7–δ on the starting Ba compounds
Authors: Farbod M. , Zargar Shoushtari M. , Gohari Bajestani N.
Published: July 2006

Y123 samples were prepared by a solid state method using BaCO3, BaO2 and Ba(NO3)2 as Ba source under same sintering conditions. The X‐ray patterns, Tc, Jc(77 K), stiffness, room temperature thermopower and lattice parameters were measured for as sintered, underdoped and well oxygenated samples. The results show these parameters are not the same for samples prepared using different Ba sources at different regime, reflecting the effect of Ba source on microstructure of Y123 compound. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum defect as a powerful tool for studying Rydberg transition energies with density functional theory
Authors: Van Faassen M.
Published: July 2006

Quantum defect analysis is applied to time‐dependent density functional theory (TDDFT) calculations of the Rydberg series of the He and Be atoms. The focus of the present study is on excitation energies obtained with different exchange‐correlation potentials and kernels. Excitation energies are reobtained from the quantum defect values, and it is shown that these energies can be very accurately obtained from knowledge of the quantum defect alone. TDDFT results are compared within the adiabatic local density approximation for the case in which all virtual states are included in the calculation with results obtained when the number of states is truncated. Quantum defect analysis is used to demonstrate that truncation leads to serious errors. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
DFT study of the electronic properties of DNA–DNA and PNA–DNA double strands
Authors: Natsume Takayuki , Ishikawa Yasuyuki , Dedachi Kenichi , Tsukamoto Takayuki , Kurita Noriyuki
Published: July 2006

The electronic properties of DNA–DNA and PNA–DNA double strands having 3–6 base pairs (bp) were investigated by density functional theory (DFT) calculations. The binding energies and the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gaps for the PNA–DNA hybrids in the vapor phase are found to be greater than those for the DNA–DNA hybrids, regardless of the number of base pairs involved. The study supports the experimental finding that PNA displays high affinity toward a complementary DNA and that PNA–DNA strands are much more thermodynamically stable than their DNA–DNA counterparts. The results suggest much higher sensitivity in DNA sequencing with the arrays of PNA than with those of DNA. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Thermomechanical wear modelling
Authors: Cowan Richard S. , Winer Ward O.
Published: July 2006

It is assumed that the contact between bodies in sliding motion produces a stress field and frictional heat source that may induce severe wear from material yielding or fracture. For this situation, a thermomechanical wear model is used to develop a wear transition equation for identifying the dominant factors that will reduce or control such wear, by employing thermoelasticity analyses and contact mechanics. This equation is used to construct wear maps for ease of analysis. Studies are used to substantiate the thermomechanical wear model with experimental results that emphasise the transition from mild to severe wear for dry and lubricated metallic and ceramic sliding contacts under load.