bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oscillations induced in EHD film thickness by a step in entrainment speed
Authors: Glovnea R. P. , Spikes H. A. 
Published: July 2006

AbstractTransient elastohydrodynamic (EHD) lubrication conditions occur in the contacts of many machine elements, such as gears, cams, and reciprocating devices, as a result of their working cycles. These conditions also occur in rolling‐element bearings at the onset or cessation of motion. The aspect of film thickness in elastohydrodynamically lubricated contacts subjected to a very rapid change in entrainment speed has not received much attention from researchers, probably because it is seen as less problematic than a sudden fall of the entrainment speed, which theoretically can lead to film failure. For a sudden stop, however, it has been shown previously that the lubricant forms an entrapment, which is able to protect the contact in many cases when the motion resumes. In this paper, EHD film behaviour under sudden acceleration is investigated; the study covers three cases ‐ starting from zero film, starting from an entrapped film, and starting from a continuous, steady film.
Effect of palm oil methyl ester and its emulsions on lubricant degradation and engine component wear
Authors: Kalam M. A. , Masjuki H. H. 
Published: July 2006

AbstractThis paper presents the results of experimental work carried out to evaluate the effect of palm oil methyl ester also known as palm oil diesel (POD) and its emulsions, as alternative fuels, on unmodified indirect‐injection diesel engine wear and lubricant oil deterioration compared with ordinary diesel (OD). A constant 2500 rpm engine setting at half throttle was maintained throughout the wear debris and lubricant oil analysis period for 20 h for each fuel system. Samples of lubricant oil were collected through a one‐way valve connected to the crankcase sump at intervals of 4 h. The first sample was collected immediately after the engine had warmed up. The same lubricating oil, a conventional SAE 30, was used for all experiments. A multi‐element oil analyser was used to measure metal wear debris and lubricating oil additive depletion for the used lubricating oil. An ISL automatic houillon viscometer (ASTM D 445) and potentiometric titration (ASTM D 2896) were used to measure the viscosity and total base number, respectively.The lubricant oil analysis results for POD, OD, and their emulsions containing 10% water by volume were compared. Very promising results were obtained. The accumulation of metal wear debris in crankcase oil samples was lower with POD and its emulsion compared with the OD fuel. The addition of 10% water (by volume) to POD showed a promising tendency for wear resistance.
Linear sulphonate detergents as pour point depressants
Authors: Li S. , Blackmon J. , Demange A. , Jao T.‐C. 
Published: July 2006

AbstractOil‐soluble metallic sulphonate detergents have been extensively used in automobile lubricants to keep engines clean and to extend their useful life. Calcium alkylbenzene sulphonate is widely used in the lubricant industry as a detergent. However, the authors have discovered that, uniquely, linear sulphonate detergents can play another role in lubricants, namely to depress the pour point of mineral oils. The authors have studied the relationship between the molecular structures of sulphonate detergents and pour point depression, and it has been found that, in order for a sulphonate detergent to be a pour point depressant (PPD), it must have a linear hydrocarbon tail. Other factors, such as the metal type, e.g., Ca or Mg, and the degree of overbasing, are not critical for pour point depression activity. A model is proposed to explain why sulphonate detergents with linear hydrocarbon tails can function as pour point depressants.
Investigation into the effectiveness of detergent—dispersant agents and additive packages
Authors: Vipper A. B. , Zadko I. I. , Ermolaev M. V. , Maslov L. L. 
Published: July 2006

AbstractComparative tests of more than 15 detergents (calcium sulphonates and phenates) of different basicity and dispersants (succinimides) were carried out using laboratory test methods. The effectiveness of the detergent and dispersant action of the test additives, their thermal, hydrolytic, and colloidal stability, and their influence on the antioxidant properties of engine oils were evaluated. The results obtained showed that it is possible to differentiate additives of various types, and demonstrated the relative efficiency of additives belonging to the same class. The effectiveness of certain additive packages was evaluated using a new approach: in addition to the laboratory methods, the retention of the dispersing ability of additive packages was evaluated in previously oxidised additivated engine oils. This allowed the efficiency of engine oils of different categories to be characterised.
Effect of MoDDP on the antioxidative properties of ZnDDP in mineral oil
Authors: Du D. C. , Kim S. S. , Suh C. M. , Chun J. S. , Moon W. S. , Kwon W. S. 
Published: July 2006

AbstractThe antioxidative actions of zinc and molybdenum dithiophosphates and their mixtures were evaluated using the RBOT (rotary bomb oxidation test) and the ISOT (Indiana stirring oxidation test). The results showed a synergistic effect on the antioxidative action with certain mixtures of the additives in mineral oil. FTIR spectra indicated the presence of some oxidation products and the degradation of the additives in the additive‐containing oils.
EP/AW performance evaluation of some zinc alkyl/dialkyl/alkylaryl‐dithiocarbamates in four‐ball tests
Authors: Verma V. K. , Singh R. , Srivastava Vandana , Singh P. K. 
Published: July 2006

AbstractTribochemistry, the chemistry of interacting surfaces under the influence of a lubricant, helps in the appropriate selection of suitable lubricant additives for specific uses. Modern lubricants are usually formulated from a range of petroleum base oils or synthetic fluids incorporating a variety of chemical additives for performance enhancement. Extreme‐pressure (EP) and anti‐wear (AW) additives are used extensively in lubricants for hypoid gears and metal cutting and forming operations to reduce wear, modify friction, and prevent scuffing of moving metallic parts.The present paper includes the synthesis and the evaluation of the tribological properties of 0.5% (w/v) solutions of some zinc bis‐(alkyl/dialkyl/alkylaryldithiocarbamates) in paraffin oil using 12.7 mm diameter steel bearing ball specimens in four‐ball tests. All the synthesised zinc dithiocarbamate additives in general, and zinc bis‐(morpholinodithio‐carbamate) (A4) in particular, exhibited good AW, EP, and friction‐reducing properties. Additive A4 especially gave low values of wear‐scar diameter and coefficient of friction at higher loads and higher values of load wear index and flash temperature parameter during EP tests (ASTM D 2783) and afforded lower values of wear‐scar diameter in a one‐hour wear test (ASTM D 2266–67).The surface topography of the wear‐scar matrix of the used ball specimens was investigated by scanning electron microscopy.
Surface‐capped molybdenum sulphide nanoparticles — a novel type of lubricant additive
Authors: Bakunin V. N. , Suslov A. Y. , Kuz'mina G. N. , Vedeneeva L. M. , Parenago O. P. , Migdal C. A. , Stott P. E. 
Published: July 2006

AbstractCompounds containing molybdenum sulphide are widely employed as friction‐modifying and antioxidant additives in lubricants. However, the synthesis of these types of compound can often be complex and expensive. Tribologically active lubricant additives can be prepared as inorganic nanosized surface‐capped particles, the surfaces being coated with compounds that interact and/or react with the inorganic material.This paper reports on the synthesis and characterisation of surface‐capped molybdenum trisulphide nanoparticles. The synthesis was carried out using a reverse micellar system. The size and composition of the nanoparticles were determined, and their tribological properties as lubricant additives were compared with those of commercially available additives. It was found that the surface‐capped molybdenum sulphide nanoparticles show good friction‐modifying and anti‐scuffing behaviour.
A simple formula for the dielectric relaxation time—temperature—pressure relationship of lubricating oils and its application to viscosity prediction
Authors: Suzuki Akihito , Masuko Masabumi 
Published: July 2006

AbstractThe dielectric constant and the loss factor for several lubricating oils were both measured within the frequency range of 100 Hz–1.5 MHz. Measurements were made at atmospheric pressure with varying temperature, and at fixed temperature with varying pressure. The temperature dependence of the dielectric relaxation time could be expressed by the Vogel—Fulcher—Tammann (VFT) equation. In order to express the dielectric relaxation time as a function of temperature and pressure, a pressure‐dependent term was introduced into the characteristic temperature of the VFT equation. The experimental relaxation time could then be represented by a simple formula. Moreover, high‐pressure viscosity was calculated from the dielectric relaxation data by introducing the pressure dependence of the bulk modulus. The predicted results showed fairly good agreement with the viscosity data.
Molecular dynamics study of the interfacial slip phenomenon in ultrathin lubricating films
Authors: Wang H. , Hu Y. Z. , Guo Y. 
Published: July 2006

AbstractThe tribological performance of thin films of a liquid alkane has been studied through a molecular dynamics simulation with particular attention being paid to the phenomenon of interfacial slip. The model system for the simulation consists of two solid walls, with the lubricant molecules confined between them. Molecules of n‐decane (C10H22) were chosen to represent the lubricant molecules. The results of the simulation show: the average velocity of decane molecules in a Couette flow exhibits largely a linear distribution, but with a slip velocity at the solid‐liquid interface; when the simulations are performed at different temperatures, the slip ratios were found to vary with temperature; slip behaviour depends strongly on the solid‐fluid interaction; and slip ratios increase with decreasing film thickness, suggesting that slip in the thin films is a confinement‐related phenomenon.
Temperature—friction characteristics of cylinder lubrication in large, slow, cross‐head marine diesel engines under boundary lubrication conditions
Authors: Stolarski T. A. , Zhou Q. , Smart M. , Green D. , Allen R. W. 
Published: July 2006

AbstractIn large, slow, cross‐head marine diesel engines research has increasingly shown that the lubrication regime between piston rings and cylinder liner at top dead centre is of the boundary lubrication type due to the high gas pressure, low sliding speed, and high temperature. This means that the tribological properties of piston ring, cylinder liner, and cylinder lubricant in these types of engine under boundary lubrication conditions should be considered simultaneously when friction and wear between the piston ring and cylinder liner are studied. Until now there has been no standard method to evaluate boundary lubrication performance. There are a few traditional methods used in lubricant research, but their results are not correlated with service conditions. It is important to find a suitable method to evaluate the boundary lubrication performance of lubricants at the laboratory testing stage or before the engine testing stage. The important parameters, such as sliding speed, normal load, materials of the contacting pairs, and lubricant, need all to be controlled.In this paper a systematic experimental procedure, the ‘five times heating and cooling test’, is introduced to assess lubricant properties under boundary lubrication conditions. Most of the parameters mentioned above are controlled. The model contact, of pin‐on‐plate form, is made from the actual piston and liner materials used in a large‐bore, slow, cross‐head marine diesel engine. The temperature characteristics of different blends of lubricants are investigated under boundary lubrication conditions using a pin‐on‐plate reciprocating test rig. These blends of lubricants have the same additives but different base fluids; they nevertheless fulfil the physical and chemical requirements of a real marine diesel engine. The test temperature range is from room temperature to the working temperature of the top piston ring.The experiments show that there are different temperature—friction characteristics for lubricants with different bases and the same additive package and there are also different temperature—friction characteristics during heating up and cooling down for each blend. Single‐base lubricants have more promising temperature—friction characteristics than those of a blend of a high‐viscosity base and a low‐viscosity base at high temperature.
Engine oil compositions based on PIB—succinimide combinations
Authors: Bartha L. , Kis G. , Hancsók J. , Baladincz J. 
Published: July 2006

AbstractAdditive packages for engine oils were prepared using PIB—succinimide combinations with different properties. PIB—succinimide‐type dispersants of various average molecular weights and dominant side effects were selected for preparing multifunctional additive combinations. A high‐molecular‐weight PIB—polysuccinimide type as viscosity‐index improver, a PIB—polysuccinimide with strong basic character as a highly effective sludge dispersant, molybdenum‐containing poly‐alkylene—polysuccinic anhydride derivatives as dispersants with complementary antifriction efficiency, and some conventional detergent, antioxidant, antiwear, and anticorrosion engine oil additives were used in engine oil compositions of various viscosity grades. The technical and economic advantages of appropriately selected and balanced additive combinations were shown by bench test results of the rheological, detergent—dispersant, and antifriction properties of the test oils.
A comparative study of phenol‐type antioxidants in methyl oleate with quantum calculations and experiments
Authors: Zhang Y. Y. , Wang H. D. , Ren T. H. , Yi M. R. 
Published: July 2006

AbstractChemical software (Gaussian 98w) was used to calculate the highest occupied molecular orbital (HOMO) energy level of three phenol‐type antioxidants to evaluate their oxidation resistance performance. The conclusion drawn from the quantum calculations was that the decreasing order of the oxidation resistance effectiveness was 4,4‐methylene‐di(2,6‐di‐t‐butyl‐phenol) (T511)>2,6‐di‐t‐butyl‐4‐methylphenol (BHT)>phenol. Pressure differential scanning calorimetry (PDSC) and the rotary bomb oxidation test were also used to assess the antioxidants in a methyl oleate base oil. According to the experimental results, the oxidation resistance capability of the three antioxidants decreased in the order BHT > T511 > phenol. The results indicated that the quantum calculation method could be used to screen antioxidants with regard to their oxidation resistance effectiveness.
Synthesis of molybdenum polyisobutenyl succinate (MoPIBS) and a study of its tribological characteristics
Authors: Fu S. F. , Tao D. H. , Zhang J. H. 
Published: July 2006

AbstractIn view of the increasing awareness of the need for environmental protection, it is considered important to have more low‐ or non‐phosphorus additives in engine oils. To this end, molybdenum polyisobutenyl succinate (MoPIBS) was synthesised and its structure investigated using spectroscopy. The antiwear and friction‐reducing behaviour of MoPIBS as an oil additive was investigated and compared to that of zinc dialkyldithio‐phosphate (ZnDDP) using a four‐ball tester. The results indicated that MoPIBS in white oil exhibits very good antiwear and friction‐reducing properties, better than those of ZnDDP, but that the load‐carrying capacity is poorer than that of ZnDDP. The worn surfaces were investigated using Auger electron spectroscopy (AES) and X‐ray photoelectron spectroscopy (XPS). It was found that the boundary lubrication film on the worn surfaces was mainly composed of MoO3 and Fe2O3, which contributed to improving the tribological properties of MoPIBS as an additive in white oil.
Study of the tribological performance of a rare earth naphthenate as a lubricant additive
Authors: Liu R. D. , Tao D. H. , Zhang J. H. , Cao W. G. , Fu S. F. 
Published: July 2006

AbstractThe tribological behaviour of a rare earth naphthenate (REN) as a lubricant oil additive in VG26 white oil and the complexes of REN and organo‐sulphur or organo‐phosphate compounds have been evaluated with a four‐ball friction and wear tester. The chemical features and elemental composition of the boundary lubricating film were examined by means of Auger electron spectroscopy (AES) and X‐ray photoelectron spectrometry (XPS). The results show that REN exhibits good antiwear, load‐carrying, and friction‐reducing properties in the base stock. When 2.0% REN is added, the wear‐scar diameter value reduces to 54.7% of that for the base stock alone and the maximum non‐seizure load increases 2.95 times. A synergistic effect is found for the load‐carrying capability of the complex of REN and organo‐sulphur while poor compatibility is exhibited for the complex of REN and organo‐phosphate. The analytical results of AES and XPS indicate that the good performance of REN is attributable to the formation of a boundary lubricating film mainly composed of naphthenic acid, rare earth oxide, and complexes of rare earth metals, which is formed on a rubbed surface when lubricated by oil containing the REN additive.
Recent achievements in the synthesis and application of inorganic nanoparticles as lubricant components
Authors: Bakunin V. N. , Suslov A. Yu. , Kuzmina G. N. , Parenago O. P. 
Published: July 2006

AbstractRecent advances made in the chemistry and technology of nano‐metric inorganic particles allow the synthesis of various metal oxides, chalcogenides, phosphates, and so on. Surface modification of nanoparticles in some cases allows the formation of stable dispersions in liquid hydrocarbons. The state of the art in the field of inorganic nanoparticle synthesis and their application in tribology are discussed in this paper. Special attention is paid to the synthesis of surface‐capped and bare molybdenum sulphide nanoparticles and to the testing thereof as friction‐modifying additives for liquid lubricants. Differences in the mechanism of action of MoSx nanoparticles and molecular molybdenum complexes (e.g., molybdenum dithiocarbamate) are discussed. Future trends in the use of inorganic nanoparticles as lubricant additives are suggested.
Characterisation and nano‐friction behaviour of molecular deposition films
Authors: Zhang S. W. , Wang Q. B. , Gao M. L. 
Published: July 2006

AbstractThe structure and the nano‐friction behaviour of a new kind of ultrathin film, a molecular deposition (MD) film, on an Au substrate were studied. The MD film is formed by the electrostatic attraction between opposite charges of cationic and anionic compounds, and a multilayer film can be built through alternating deposition of bipolar cationic and anionic compounds. Monolayer, bilayer, trilayer, and tetralayer MD films on Au substrates were examined. MD films with an alkyl terminal group were also investigated. It was found that while the MD film on an Au substrate reduced the friction, its nano‐friction behaviour was unstable because of the active terminal group. However, if the MD film was formed with an alkyl terminal group, its nano‐friction behaviour became stable and its friction decreased markedly. Therefore, this film termination method could contribute to the nano‐tribological application of MD films.
Rheological properties of high‐viscosity‐index mineral base oils for automotive engine lubricants
Authors: Muraki M. , Dong D. 
Published: July 2006

AbstractViscosity‐pressure‐temperature relations for paraffinic mineral base oils at pressures up to 0.7 GPa and temperatures between 30 and 90°C were determined using a falling‐ball‐type viscometer. The oils used were solvent refined oils, hydrocracked oils, and an oil produced by a wax isomerisation process. The viscosity at pressures higher than those possible with the viscometer was then derived by applying a simplified solution to the traction curves determined using an elastohydrodynamic disc‐on‐ball tester. When the measured viscosity and the calculated viscosity were plotted against pressure, for the oils with a viscosity index higher than 120 the viscosity derived from traction measurements followed the curve extrapolated to the high‐pressure region using either the Yasutomi or Roelands equations (the parameters for which were obtained using the viscometer). However, the calculated viscosity for the lower‐viscosity‐index oils deviated upwards from the extrapolated curve.
The mechanical generation of emulsions
Authors: Dalmazzone C. 
Published: July 2006

AbstractEmulsions are complex systems frequently encountered in our daily lives and in most industrial sectors, including the oil industry. An understanding of the mechanisms of emulsion formation is essential both to create them and to treat them. The present work describes the main phenomena that come into play in emulsifying. The break‐up of droplets in either laminar or turbulent flow is discussed, and certain correlations, from which the diameter of the droplets formed can be predicted, are given. The role of surfactants is also examined, as are the typical time scales of the various processes involved.
Friction and nanowear of polystyrene against hydrophobic and hydrophilic substrates
Authors: Ghorbal Achraf , Bistac Sophie , Schmitt Marjorie 
Published: July 2006

AbstractThe ambition of this study is to analyze the role of interfacial interactions in friction and nanowear of polystyrene, by comparing friction against hydrophobic wafers (methyl‐terminated) and hydrophilic wafers (hydroxyl‐terminated) as a function of sliding velocity and normal force. Friction experiments are performed with a translation tribometer and nanowear investigation is achieved by using atomic force microscopy (AFM) analysis of the wafer surfaces after friction. Experimental results show that the friction coefficients measured on hydrophilic surfaces are always larger than those obtained with hydrophobic surfaces, indicating a relationship between friction and interfacial interactions. Elsewhere, AFM analysis shows that polystyrene transfer appears for a higher normal force in the case of hydrophobic substrates compared to hydrophilic one. However, the corresponding tangential (or friction) force necessary to detect transfer is quite similar for both types of substrates, indicating that the initial wear of polystyrene occurs for a similar threshold interfacial shear. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2449–2454, 2006