bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three‐dimensional incompressible flow of a gas through feed holes into an annular space of finite length
Authors: Uneeb M. , Gohar R. 
Published: July 2006

AbstractThis paper presents a theoretical model of the three‐dimensional flow of an incompressible gas in a concentric double‐plane admission externally pressurised gas journal bearing. Inertia effects and the discreteness of the feed holes are included. The flow map demonstrates the formation of a vena contracta at the commencement of the film, downstream of the feed holes, as well as detailed behaviour of the streaklines within the film. The pressure profile obtained shows a depression at the vena contracta, followed by a partial recovery which varies around the feed holes, depending on whether the local flow is exiting between the rows of holes or outboard towards atmosphere. A comparison is also made with a similar one‐dimensional incompressible flow solution to obtain flow and pressure factors, to account for the discreteness of the feed holes as well as inertia effects.
Lubricating oil additives and the environment — an overview
Authors: Herdan J. M. 
Published: July 2006

AbstractIn this paper are reported some practical considerations relating to lubricant additive manufacture, and to additivated lubricants' impact on the environment. Widely used engine oil additives are mainly dithiophosphates, overbased calcium sulphonates, succinimidic dispersants, and polymer VI improvers. Production of these additives creates a potential environmental problems due to the hazardous emissions such as H2S and HCl and sludge obtained during purification. New processes are described which lead to the reduction of toxic and other harmful pollutants.Gear oil additives, although these may be used in lower amounts, also make for ecological problems. A high quantity of sulphur‐containing waste water is produced during manufacture of sulphurised EP additives. Some possibilities for recovering sulphur from this waste water are presented. The reduction of the chlorine content in EP additives is another important task, and new processes to produce EP additives with low residual chlorine content are discussed. Metal working fluid additives comprise emulsifiers, corrosion inhibitors, antiwear and EP additives. Their fabrication usually produces toxic and harmful residual products. Additivated lubricants may promote ecological injury. Oil leakage from engines working in harbours, parks, and entertainment areas are dangerous and difficult to avoid. To counter this, biodegradable base stocks were developed, but there are few data concerning the biode‐gradability of the additives used. Used oils are generally collected and recovered, but a significant quantity of used oil is directly burned. Burning of additivated used oils in incorrect equipment leads to dangerous emissions, such as sulphur oxides. Because sulphur‐containing additives cannot be replaced in engine oils or gear oils, the main ecological measure is the reduction of the quantity of used oils burned.
Interaction of PIB‐succinimides and other engine oil additives
Authors: Bartha L. , Deák Gy. , Kovács M. , Kocsis Z. , Vuk T. 
Published: July 2006

AbstractThe paper shows the results of investigations into the interactions between different types of succinimides and zinc dialkyl dithiophosphates. Various properties of additives in oil solutions were tested and examined by various methods, in order to show the existence of interactions of various strengths between different types of succinimide and ZnDDP.
Relationship between the structure of C60 and its lubricity: A review
Authors: Bo Feng 
Published: July 2006

AbstractBased on analyses of the calculations of quantum theories, such as electron charge density, the energy level distribution of orbitals, and the forces between C atoms and between the molecules in C60 crystals, the author concludes that C60 crystal is a promising solid lubricant. Furthermore, owing to the unique spherical structure of its molecules, high chemical stability, and the phase transition of the crystal fullerene C60 may have some particular tribological properties that are superior to traditional graphite and MoS2, especially under crucial conditions such as high vacuum, high pressure or in a humid environment. The tribological tests that have been reported show the lubricity of fullerene C60, and the effects of the lubricating properties of C60 on some metals are also predicted.
Lubrication safety in high‐speed ball‐bearings
Authors: Olaru D. N. , Gafitanu M. D. 
Published: July 2006

AbstractIn a 7206 C high‐speed, mist‐lubricated ball‐bearing, both the film thickness and lubricant parameter λ in ball—race tribo‐systems have been analytically investigated in terms of starvation and thermal effects, and good correlations with experimental results were obtained for 5,000 to 35,000 rpm rotational speeds. Including a lubricant parameter in ball—race tribosystems as a safety criterion for ball‐bearings, friction losses, temperature, and limit speeds have been correlated with this criterion for a 7206 C ball‐bearing. Friction losses in ball‐outer race tribosystems have been computed for both EHD and mixed lubrication regimes. The influence of the bricant parameter on friction losses has been shown both theoretically and experimentally. A new speed limit concept including the lubricant parameter λ, has been developed by the authors.
Production of a transformer oil from paraffinic basestocks
Authors: Abou El Naga H. H. , Anis A. , Salem A. E. , Boghdady Y. M. 
Published: July 2006

AbstractThe work described in this paper is concerned with the production of a high quality transformer oil from local Egyptian paraffinic basestocks. Analysis showed that a neutral base oil 70N was most suitable for producing transformer oils. This neutral base oil was chemically treated with a sulphonation process. Optimum sulphonation conditions were achieved by using oleum or SO3 at a concentration of 6 wt. %. The sulphonation reaction was carried out in three stages, each with an equal portion of the sulphonating agent. The acidic oil was then neutralised with an alkaline solution. Oil colour improvement was effected using activated clay as an absorbent. Laboratory results and field trials indicated that such a treated neutral paraffinic oil meets the IEC 296 international specifications for transformer oils, with the exception of pour point (−12°C). However, such a pour point is not relevant in certain hot climatic conditions. Comparative evaluation of the treated oil with commercial transformer oils has shown its suitability.
Prediction of oxidation stability of inhibited base oils from chemical composition using an artificial neural network (ann)
Authors: Basu B. , Saxena D. , Kaul V. , Sastry M. I. S. , Mookken R. T. 
Published: July 2006

AbstractOxidation stability is the single most important characteristic of lubricants that affects their service life and high‐temperature applicability. The chemical composition of base oils determines to a large extent the oxidation stability of the lubricants. For steam turbine oils, oxidation stability is more important still, as the oil is expected to remain in the system for 10–20 years. Selection of appropriate base oils, therefore, is crucial for the formulation of turbine oils. The oxidation stability of turbine oils is estimated by three bench tests, ASTM D‐943, ASTM D‐2272, and IP 280, which vary in severity, and are all time‐consuming. In this context, the prediction of oxidation test performance (oxidation stability) of base oils from their chemical composition appears to be very attractive.
Additive—additive interaction: A study of the ep and AW performance of sulphurised jojoba oil and sulphurised xanthate in the presence of mocontaining friction modifiers
Authors: Gupta A. K. , Bhatia H. C. , Tuli D. K. , Verma A. S. , Rai M. M. , Bhatnagar A. K. 
Published: July 2006

AbstractThe extreme‐pressure (EP) and antiwear (AW) performance of three soluble molybdenum compounds (commercial molybdenum dialkyldithiophosphate, commercial molybdenum dialkyl dithiocarbamate, and synthesised molybdenum dialkyl dithiocarbamate), and two sulphur‐containing EP compounds (sulphurised jojoba oil and sulphurised O‐stearyl‐S‐oleyl xanthate) have been studied alone and in combination, using a four‐ball tester. The behaviour of the additives in combination has been found to be selective, and dependent on the chemistry and ratio of the additive components. In general, the addition of Mo‐type friction modifiers (FM) to sulphurised EP compounds has shown a synergism, of varying order, in their EP and AW properties.
The kinetics of degradation of styrene‐isoprene copolymer
Authors: Desai N. M. , Joshi N. C. 
Published: July 2006

AbstractViscosity modifiers are one of the most important components of multi‐viscosity grade lubricants. In use, the lubricant heats up and the ingredients degrade and deplete. In an attempt to understand the thermal and thermal‐oxidative behaviour of viscosity modifiers, we have studied the effects of heat in both inert and oxidative atmospheres. The paper describes the degradation of a styrene‐isoprene viscosity modifier studied with differential scanning calorimetry (DSC). Most of the kinetic parameters can be obtained by the application of Kissinger, Ozawa, and Augis and Bennett's simple expressions, which are special cases of Elder's formulations. The values of order, heat of degradation, and activation energy were +1.25, +1149 J·m, and 175 kJ·mole for thermal degradation in a nitrogen atmosphere, and +1.50, −6321 J·m, and 57 kJ·m for thermal‐oxidative degradation in air. The information concerning the degradation of the viscosity modifying polymers can be useful in selecting the correct polymers for envisaged application.
The effect of the aromaticity of base stocks on the viscometric properties of multigrade oils
Authors: Abou El Naga H. H. , Abd El Aziem M. W. , Mazin A. S. 
Published: July 2006

AbstractThe viscometric properties of multigrade oils containing base stocks with increased aromatic content have been studied. Various types of viscosity index improvers (VIIs) have been incorporated in these formulations. Viscosity measurements were carried out over a wide temperature range (from −10°C to 150°C).The results show that increasing the aromaticity of blends induces a greater thickening effect with all types of VIIs incorporated, but by different magnitudes. This thickening effect is more pronounced at low temperatures. At high temperature and high aromaticity, the VIIs tended to acquire high swelling behaviour, which serves to mask the differences between them.Limited changes were noticed for the viscosity index, thickening tendency, and specific viscosity of the blends tested. The shear stability of the VIIs was found to decrease with the increasing aromaticity of the blends. Such behaviour can be attributed to the swelling of the VIIs and the increase in their molecular volume, which consequently facilitated their shearing.
Friction reduction and antiwear properties of the complex of lanthanum and a phosphate
Authors: Shengrong Yang , Yubin Sun , Weimin Liu , Pingyu Zhang , Zefu Zhang 
Published: July 2006

AbstractA complex of lanthanum and di‐(2‐ethyl hexyl) phosphate (DEHP) was prepared by an extractive method. The friction and wear behaviour of this complex (called LaDEHP) as an oil additive was evaluated using a four‐ball wear tester. For comparison, the friction reduction and antiwear properties of DEHP as an oil additive were also investigated. The chemical composition of the boundary film formed after wear tests was examined using X‐ray photoelectron spectrometry (XPS).Four‐ball tests showed that the prepared LaDEHP was effective in reducing friction and wear as well as in increasing load‐carrying capacity. XPS analyses indicate the formation of iron phosphate and lanthanum oxide in the boundary films.
Rheological modification of base oils using a styrene‐isoprene copolymer
Authors: Desai N. M. , Joshi N. C. 
Published: July 2006

AbstractIn trying to understand the behaviour of solutions of polymer in mineral oils, a styrene‐isoprene copolymer and two mineral oils have been studied. The base oils showed Newtonian behaviour, and the polymer solution non‐Newtonian behaviour, in the temperature range 50–100°C. The variation of viscosity with shear rate can be approximated to a power law model within the same temperature range and 0–104 s−1 shear rate. The free energy of activation is used to explain the flow behaviour qualitatively.
Physical and chemical modification of zinc carboxylate‐containing lubricants by molecular structure changes
Authors: Andor J. A. , Berkesi O. , Dreveni I. , Varga E. 
Published: July 2006

AbstractTwenty‐two samples of zinc carboxylates were prepared from saturated, non‐cyclic carboxylic acids with systematically altered hydrocarbon chain structures under well‐defined conditions. Essential temperature‐ and solvent‐induced changes concerning the coordination of the carboxylate group are shown using selected prepared samples, and general rules for systems containing zinc carboxylates in nonpolar media are presented.It is shown that there are three possible structural forms for zinc carboxylates: polymeric sheet, polymeric chain, and closed tetranuclear oxo complex molecules. These forms are closely related through their physical and chemical transitions.The results show that the spatial structure of the hydrocarbon chain is a crucial factor, besides physical and chemical conditions, limiting the possible forms of zinc carboxylates present in the system. The principles presented enable us to predict and design the behaviour of a system containing zinc carboxylate additives.
Effects of type of lubricant and shape of tooth profile upon efficiency of gear drives
Authors: Ishibashi A. , Sonoda K. , Mohammad H. Ali 
Published: July 2006

AbstractTo reduce energy consumption, it is important to increase the efficiency of gears used for power transmission. In the present work, the efficiencies of gear drives with standard and profile shifted involute gears are measured by changing the type of lubricating oil. A new equation for calculating efficiency is derived by taking into account the additional friction torque that depends on the shape of the teeth. The efficiencies calculated with the new equation agree well with those obtained by experiments conducted using two planetary gear drives with different tooth shapes and with different reduction ratios (u = 4. 89 and 151). The new equation is applicable to the design of gear drives with higher efficiency.
Lubrication behaviour of iron rhenate in relation to matching pairs at elevated temperatures
Authors: Dangsheng Xiong , Shizhuo Li 
Published: July 2006

AbstractIron rhenate was compounded by a chemical method, which can be reproduced during the wear process of Fe‐Re alloys at elevated temperatures. The friction coefficient of iron rhenate was determined using five types of ball material (Si3N4, Al2O3, glass, 440 C, and Hast C) matching seven types of disc material (Al2O3, 761 iron base superalloy, glass, stainless steel, bronze, copper, and Al‐Li), using a ball‐on‐disc device. The results show that the iron rhenate plays a role in lubrication from room temperature to 600°C. The lubrication behaviour is related to the nature of the matching pairs: the hardness of the materials, the compatibility of iron rhenate with the materials of the matching pairs, and the surface roughness of the disc most affect the lubrication behaviour of iron rhenate. The principle of tribologically matching pairs is proposed.
A review of ultrafine particles as antiwear additives and friction modifiers in lubricating oils
Authors: Sunqing Qiu , Junxiu Dong , Guoxu Cheng 
Published: July 2006

AbstractThis paper gives an overview of developments in the use of ultrafine particles in lubricating oils to reduce wear and friction. Work on several types of particles, such as graphite, MoS2, PTFE, BN, fullerene, and Cu, as well as more novel and unusual particles used as lubricant additives, is reviewed. The paper summarises the results of a number of workers in this field. The tribological mechanism by which ultrafine particles operate is considered, and some conclusions, including possible future directions for research, are drawn.
The influence of lubricating greases on rolling bearing failure
Authors: Rakić Radoslav , Rakić Zlata 
Published: July 2006

AbstractSignificant savings can be made by the correct use of lubricants in terms of energy consumption, replacement parts, maintenance costs and the reduction of machinery downtime, because the service life of machines is one of the most important aspects of engineering. Planned preventive maintenance means the minimisation of failures and of maintenance costs; the technology should allow identification of the tribomechanical systems in all operating conditions and of the tribological regime and duration of operation. Despite the enormous advances that have been made over the last thirty years in the theory of rolling bearing lubrication, the successful operation of rolling bearings remains highly dependent on empirical knowledge. The aim of the present study is to investigate the influence of lubricating grease on rolling bearing failure; the experimental work was carried out at a metalworking factory.
Preparation of medicinal petroleum Jelly using local petroleum Waxes
Authors: Battarjee S. M. , El‐Azim W. M. Abd , Mohamed A. A. 
Published: July 2006

AbstractPetroleum waxes are mainly derived from paraffinic crudes. These waxes must be removed from lubricant base oils through a dewaxing process to avoid affecting oil performance at low temperatures. The waxes themselves have uses.This paper describes successful attempts to select the optimum conditions for sulphonation and/or hydrogenation of local waxes to obtain medicinal macro‐ and microcrystalline waxes suitable for use in petroleum jelly blends that meet medicinal specifications.Deoiling was carried out to separate the oil from the wax samples. Concentrated and fuming sulphuric acids were used as sulphonating agents. Sulphonation processes were carried out at different temperatures, stirring speeds, and digestion times. The optimum sulphonation conditions, which give 0.007 UV absorbance at 290 nm and the highest yield, were achieved using 28% concentrated sulphuric acid.The optimum hydrogenation conditions were achieved using a Ni/Mo catalyst at 105°C and 60 bar for paraffin wax and 180°C and 100 bar for petrolatum, for 30 min for both types of waxes.Analysis and field trials of the blended petroleum jelly showed that these blends meet British Pharmacopoeia specifications.
Viscometric properties of viscosity index improvers in lubricant base oil over a wide temperature range. Part I: Group II base oil
Authors: Lariviere D. , Asfour Abdul‐Fattah A. , Hage Alek , Gao J. Z. 
Published: July 2006

AbstractCapillary viscometry has been employed to measure the viscosities of dilute polymer solutions over the temperature range ‐10 to 150 °C. A Group II base oil containing 95% saturates was used as solvent for an olefin copolymer (OCP), a hydrogenated diene copolymer (HDP), and a polymethacrylate (PMA). These three polymers represent the three major families of viscosity index (VI) improvers used nowadays in lubricant formulations. Intrinsic viscosities and Huggins' constants were also determined. The thickening effects of the olefin copolymer and the hydrogenated diene copolymer were found to be higher at low temperatures (e.g., 40 °C) than at higher ones (e.g., 100 °C), which phenomenon was attributed to stronger intermolecular hydrodynamic interactions at low temperatures, as indicated by the Huggins constants. For the hydrogenated diene copolymer and the polymethacrylate polymer, the viscosity increased abruptly when the temperature went below 10 °C. This unusual observation was attributed to the crystallisation of a small fraction of the base oil. Based on the intrinsic viscosity data, it was concluded that at temperatures between 10 and 150 °C, the polymer coil dimension remains a constant for the olefin copolymer and the hydrogenated diene copolymer VI improvers, but increases with increasing temperature for the polymethacrylate VI improver.
An experimental study of elastohydrodynamic central and minimum film thicknesses for various material parameters
Authors: Křupka I. , Poliščuk M. Hartl R. , Liška M. 
Published: July 2006

AbstractA newly developed experimental technique, based on colorimetric interferometry, has allowed accurate measurement of central and minimum elastohydrodynamic (EHD) film thickness for a wide range of operating conditions. This study was aimed at determining the influence of various material parameters on central and minimum EHD film thicknesses. Obtained experimental data were compared with Hamrock and Dowson film thickness equations and a numerical solution presented by Venner. The results obtained confirmed that the ratio between the central and minimum film thicknesses changes significantly with both load and material parameters.
A tribological study of a ternary complex of zinc with dioxyethylenated octylphenol phosphate in water
Authors: Feng Lin , Mi Zhou , Yu‐kai Hu , Wen‐long Zhang , De‐Hua Tao 
Published: July 2006

AbstractA novel aqueous antiwear additive, a ternary complex of zinc with dioxyethylenated octylphenol phosphate and triethanolamine (TXOZ + TEA), has been synthesised. Its tribological behaviour in water was evaluated using a four‐ball tester. The results indicate that the complex in water exhibits higher load‐carrying capacity than mineral oil plus ZDTP, and excellent antiwear behaviour. The elemental composition of its rubbed surface was investigated with Auger electron spectroscopy (AES), and the results of this analysis are presented in the paper. The action mechanism of the additive is also discussed.
Oil film thickness measurement by means of an optic lever technique
Authors: Glavatskikh Sergei B. , Larsson Roland 
Published: July 2006

AbstractOil film thickness in hydrodynamic bearings is a fundamental parameter influencing overall hydrodynamic bearing performance. Knowledge of this thickness allows bearing performance to be optimised. For the small hydrodynamic bearings that are usually used in laboratory test facilities, a very small sensor (e.g.,<2 mm) is required because of space limitations. Commercially available eddy‐current and capacitance sensors are too large to be mounted in the pad of such a bearing. An alternative approach is to use sensors based on optical methods, such as the optic lever technique. The main idea in this technique is to detect the intensity of a light beam reflected from a target surface. This intensity is a function of the distance between the sensor and the target. This paper reports the specific features of the optic lever technique as used for measurements of oil film thickness. The design, calibration procedure, and main characteristics of an optical sensor are discussed. A test rig for the calibration of oil film thickness sensors is also presented. The sensor response curve has two parts, linear and non‐linear; using the linear part results in high sensitivity in the micrometre range. The influence of different types of oil on the output signal of the sensor has also been investigated. Experiments with different target velocities have shown that this sensor can be used for accurate and reliable measurement of oil film thickness in hydrodynamic bearings.