bluuebunny/crossref_metadata_2025_split huggingface dataset:
A tribological study of (2‐sulphurone‐benzothiazole)‐3‐methyl‐dibutyl borate
Authors: Weijiu Huang , Junxiu Dong , Fenfang Li , Guoxu Chen , Boshui Chen 
Published: July 2006

AbstractAn organic compound containing S, N, B, and O was synthesised by reacting 2‐mercaptobenzothiazole and formalin in ethanol solution, the resulting product then being reacted with butanol and boric acid in toluene solution. The tribological performance of the novel compound when added to liquid paraffin was evaluated using a four‐ball tester and a ring‐on‐block machine. The relationship between performance and concentration was analysed, and the results show that the compound possesses good antiwear and load‐carrying abilities. The mechanism of action of the additive was investigated using X‐ray photo‐electron spectroscopy (XPS). Surface analysis indicated the formation of a protective film containing FeSO4, an organo‐sulphur compound, FeS2, borate, and an organonitrogen compound. This protective film formed during sliding processes contributes to the increase in wear resistance.
Geometric effects in high‐temperature vapour‐phase lubrication using hydrocarbon feed gases
Authors: Gardner J. E. , Sawyer W. G. , Blanchet T. A. 
Published: July 2006

AbstractThe effectiveness of ‘far‐field’ vapour‐phase lubrication, in which areas of a bearing surface that are cycled through the contact are exposed to vapour while outside the contact, has been demonstrated in both sliding and combined roll slide tests using acetylene vapours to deposit pyrolytic graphite. Friction coefficients as low as μ = 0.008 have been measured for steel at 540°C with far‐field acetylene concentrations as low as 5%. Effective vapour‐phase lubrication depends on solid lubricant deposition that exceeds the contact's capacity to remove solid lubricant through wear. While the rate of removal is increased by increasing the sliding velocity, in far‐field vapour‐phase lubrication the rate of lubricant deposition, and therefore the lubrication effectiveness, is augmented by increased areas available for far‐field deposition, such as those provided by performing wear tests with increased wear‐track diameters. These geometric concepts may be considered in rolling‐element bearing and gear set applications where vapour‐phase lubrication is to be employed.
Film‐forming additives ‐ direct and indirect ways to reduce friction
Authors: Spikes H. A. 
Published: July 2006

AbstractThis paper reviews the current understanding of lubricated contacts and the origins of friction in terms of the Stribeck curve. It discusses the various ways that lubricant additives can modify friction in thin‐film lubricated contacts, examining both the nature and properties of the films formed by these additives, as revealed by film thickness measurements, and their consequent effect on the Stribeck friction curve.
Lubrication potential of boron compounds: An overview
Authors: Choudhary R. B. , Pande P. P. 
Published: July 2006

AbstractBoron compounds are emerging as promising materials for a wide range of applications in automotive and industrial lubrication systems. Several studies conducted on boron compounds have revealed that they exhibit desirable properties for preparing stable and compatible lubricant components for a new generation of lubricating oil formulations. Boron‐containing lubricants have major tribological advantages, such as antiwear efficiency, good film strength, high‐temperature resistance, and self‐lubricating properties. The increasing number of patents concerning boron‐containing lubricants illustrates commercial interest in this area. Boron lubricants can be used in many forms, such as oxides, esters, and boric acid. Therefore, it can be expected that a new generation of lubricant formulations includes boron compounds. This paper presents an overview of various solid and liquid lubricants containing boron as an important ingredient, and is intended to aid the development of new lubricants.
Effect of the structure and metal atom of dialkyldithiophosphate derivatives on the wear behaviour in steel‐zirconia contacts
Authors: Margielewski L. , Stanecka R. 
Published: July 2006

AbstractWear investigations concerning the different structures and metal atoms of metal dialkyldithiophosphates (MeDTPs) were conducted using a ball‐on‐disc apparatus. Steel ball bearings (3.175 mm in diameter) and counterface discs, made of hot pressed ZrO2 partially stabilised by Y2O3, were used. The synthesised MeDTPs were made up of primary linear aliphatic alcohols with hydrocarbon lengths varying from 8 to 16 carbon atoms, and contained the following metals: zinc(II), iron(III), gallium(III), antimony(III), and copper(II). Tests were performed at room temperature. The sliding speed was set to a constant 0.03 m/s, and a constant 30 N load was used. The additives investigated were used as solutions in n‐hexadecane.The study also focused on the influence of additive concentration on wear. It was found that the effectiveness in reducing wear depends both on the metal atom and on the length of the hydrocarbon chain in the additive's molecules. The lowest wear volumes were observed for additives with n‐octyl and n‐tetradecyl hydrocarbon chains. The worst antiwear performance was observed for n‐dodecyl derivatives. For almost all additives, more concentrated solutions resulted in less wear. Some friction coefficient results are also presented.
Borate esters used as lubricant additives
Authors: Yao J. B. , Wang Q. L. , Chen S. Q. , Sun J. Z. , Dong J. X. 
Published: July 2006

AbstractBorate esters possess friction‐reducing, antiwear, and anti‐oxidant characteristics when blended in lubricating oils. However, borate esters are susceptible to hydrolysis. The formation of a stable five‐member ring structure in the ester molecules, involving coordination of nitrogen with boron, contributes substantially to the resistance to hydrolysis of borate esters. The susceptibility of borates to hydrolysis can be reduced by introducing N,N‐dialkylaminoethyl groups with alkyl radicals containing more than three carbon atoms. X‐ray photo‐electron spectroscopy and X‐ray diffraction reveal that the borate ester can be adsorbed on the rubbing surface, and some of the adsorbed borate film degrades and forms boron nitride. Four‐ball wear tests indicate that the combination of oil‐soluble copper, tin, and cadmium compounds with organoborates gives better antiwear properties than the components separately. An antiwear synergistic mechanism is postulated in which borates with electron‐deficient boron p orbitals catalyse the tribo‐reduction of the metal compounds on the rubbing surfaces, producing elemental metals.
Basics: Current base oil quality and technological options for its improvement— an Overview
Authors: Anwar M. , Kaushik R. S. , Srivastava Manoj , Kumar Manoj , Garg M. O. 
Published: July 2006

AbstractRecent technological developments have revolutionised the lubricant industry by spurring a widespread quality improvement in both base oils and additives, giving superior finished lubricants. The upgrading of base oils is being brought about by more demanding requirements from original equipment manufacturers (OEMs), by government regulations, and through consumer awareness, environmental concerns, decreasing supply of high‐quality lubricant‐bearing crudes, and expanding markets worldwide.Present‐day lubricant demand is for maximum oxidation stability, superior low‐temperature performance, low volatility, and improved additive response, which are difficult to achieve through conventional processing. Conventional solvent lubricant refining produces base oils with a viscosity index (VI) of 100 with a fair amount of sulphur and aromatics, i.e., Group I base oils only. The current requirements of high‐performance base oils can conveniently be met through the hydroprocessing route. Depending upon the severity level, hydroprocessing is able to produce base oils of VI 95–110, in addition to low sulphur and high saturates content (Group II and Group III) by transforming the undesirable molecules into more useful structures. In countries such as India, a hybrid approach offers a technical solution to meet current demands for lubricant quality. This approach can be implemented in existing lubricant refineries without entailing major changes in refinery configuration, besides being cost‐effective.This paper describes the current requirements of modern lubricants in relation to API Groups and trends in these, and describes a sequence of technologies involving solvent refining, a cost‐effective hybrid scheme, and more recent hydroprocessing that allows a cost‐effective upgrading of Group I refining process. A case study is given that discusses the adoption of the hybrid scheme in Indian refineries.
Application of quantitative 13C nuclear magnetic resonance spectroscopy to the characterisation of solvent‐refined aromatic‐rich lubricant base oils
Authors: Adhvaryu A. , Erhan S. Z. , Singh I. D. 
Published: July 2006

AbstractNuclear magnetic resonance (NMR) spectroscopy has emerged as a powerful technique for studying the molecular composition of base oil matrices. The usefulness of this technique lies in its ability to explain the chemistry involved in the molecular changes observed in various lubricant refining and extraction stages. This paper discusses the use of this technique in understanding the variation of gross properties observed in base oils during lubricant processing steps. The variations in weight percent of sulphur, viscosity index (VI), Conradson carbon residue (CCR), characterisation factor (KUOP), etc., are explained at the molecular level using high‐resolution quantitative 1H and 13C NMR. A single well‐recorded quantitative spectrum of a sample can be used to generate sufficient information on the different properties used for the specification of base oils.
Friction‐induced two‐dimensional solid films from lubricant additives
Authors: Martin Jean‐Michel , Grossiord Carol , Varlot Karine , Vacher Béatrice , Le Mogne Thierry , Yamada Yasuhisa 
Published: July 2006

AbstractTribochemical interactions between some lubricant additives, namely zinc dithiophosphate (ZnDTP), an antiwear additive, molybdenum dithiocarbamate (MoDTC), a friction modifier, and overbased calcium borate (OCaB) detergent, have been investigated. The nature of the tribofilms formed was studied by combining high‐resolution transmission electron microscopy of wear fragments and inside wear scars with micro‐spot X‐ray photoelectron spectroscopy at the same location of the wear track (‘dual’ analysis).The OCaB/ZnDTP/MoDTC ternary system provides both a low wear rate and ultralow friction, while adding detergent and anti‐corrosion properties to the formulation. The analytical data indicate that such a synergistic effect can be attributed to an outstanding feature of the tribofilm nanostructure: it is composed of perfectly oriented MoS2 single sheets embedded in a single‐phase calcium and zinc borophosphate glass. Compared to phosphate alone, MoS2 sheets are oriented by the borophosphate phase. This could be related to a template effect of friction‐aligned planar molecules of the glassy borate polymer.
Influence of the structure of polysulphide additives on the shiftability of manual transmissions
Authors: Shirahama Shinichi , Ohkawa Tetsuo 
Published: July 2006

AbstractThe shiftability of manual transmissions is known to be strongly affected by the nature of the transmission oil. When conventional sulphur—phosphorus (SP) additives are used in the oil, gear clashing, sticking, and other problems occur. As reported previously, these problems are caused mainly by the polysulphide used in the SP additives. This paper reports on a study of the effect of the structure of the polysulphide's hydrocarbon chain on the synchromesh characteristics. It is found that polysulphides with long hydrocarbon chains have high kinematic friction coefficients and low static friction coefficients. It is also shown that this phenomenon occurs because of the adsorption of the polysulphide on to the copper alloy of which the gear synchroniser ring is made. By using a polysulphide with a long hydrocarbon chain it is possible to develop transmission oils that have superior load‐carrying capacity and better shiftability even when compared with the latest transmission oils that contain metallic detergents.
Lubrication at 750°C in a vacuum by a transfer film from self‐lubricating composites for roll/slide contact of Si3N4
Authors: Suzuki M. 
Published: July 2006

AbstractRoll/slide friction tests were carried out at a temperature of 750°C in a vacuum. Disc specimens were made of Si3N4 with or without a sputtered MoS2 film. A pin specimen was rubbed against one disc to supply a lubricating transfer film. With a pin made of an MoS2‐based composite, the friction coefficient was around 0.3 and almost no wear of the discs was observed after 24 h of operation at a load of 50 N, a rotating speed of 0.5 m/s, and a slip ratio of 10%. Transferred patchy MoS2 films were observed on the friction track. With a pin made of Ni‐based composite containing BN and graphite, the friction coefficient increased from 0.2 to 0.7 over a test time of about 8 h and severe disc wear was found. In an additional test using Si3N4 discs with a sputtered MoS2 film without a pin, the friction coefficient was about 0.3, and no wear of the discs was found after 24 h of operation. The appearance of the friction track was similar to that in the test using the MoS2‐based composite pin. It seems that the sputtered MoS2 film wore, but wear particles reattached on the friction path to develop an effective lubricating film. These results demonstrate the effectiveness of transfer film lubrication for long‐term operation in a high‐temperature vacuum, and the superior ability of MoS2 to develop an effective transfer film.
Influence of surface roughness features on mixed‐film lubrication
Authors: Choo J. W. , Olver A. V. , Spikes H. A. 
Published: July 2006

AbstractAn optical technique (three‐dimensional spacer layer imaging) has been developed to map accurately lubricant film thickness in thin‐film elastohydrodynamic (EHD) contacts. This experimental technique has been used to study the influence of surface roughness features, asperity height, and slope on EHD film thickness and pressure. Single ridges transverse to the entrainment direction were used to represent asperities. It was found that the ridges with lower slopes generate films of greater minimum thickness. Below a certain entrainment speed, the minimum film thickness declined at a rate dependent on the ridge slope. At low speeds, the ridges with higher slopes entrapped a larger volume of lubricant ahead of the ridge and along the entrainment direction. For all speeds, the highest ridges entrapped the most lubricant. Both ridge slope and ridge height had a negligible effect on mean film thickness in the contact. Asperity pressure increased with higher ridge slope, but was not influenced by entrainment speed. An increase in pressure was found where lubricant is entrapped upstream of a ridge.
Comparison of an optimum‐profile hydrodynamic thrust bearing with a typical tilting‐pad thrust bearing
Authors: Wasilczuk M. 
Published: July 2006

AbstractThe oil gap profile in a hydrodynamic thrust bearing exerts a great influence on the bearing properties, and hence the optimisation of the oil gap profile is one method for improving the bearing properties. In the present work, the properties of two hydrodynamic thrust bearings have been experimentally compared under realistic load/ speed conditions. One was a typical tilting‐pad bearing and the other was an unconventional bearing with an elastic thrust plate. The latter was designed using oil gap profile optimisation and design parameter selection. Owing to the design method used, the oil gap profile was close to optimum for the assumed load/speed conditions. The results show a substantial increase in the minimum oil film thickness and lower temperature in the bearing with the elastic thrust plate. This improvement of properties is thought to be because of the optimised oil gap profile in the bearing.
Copolymeric succinamic acids as antiwear additives: Synergistic and adverse effects
Authors: Mehrotra A. K. , Nandi T. , Agnihotri R. K. , Mathur G. N. 
Published: July 2006

AbstractCopolymeric succinamic acid (COSMA) additives have been synthesised in the laboratory and evaluated for their antiwear performance, both alone and in combination with zinc dialkyl‐dithiophosphate (ZDDP) in HVI light neutral oil. COSMA additives show antiwear behaviour and, in combination with ZDDP, exhibit a good synergistic effect, reducing the wear‐scar diameter by 60% and increasing the initial seizure load from 50 kg to 85–95 kg.
Tribochemical effect of impurities in zinc dialkyldithiophosphate in engine oil
Authors: Hu Xianguo , Wo Hengzhou , Han Guopei , Lu Yaling 
Published: July 2006

AbstractThis study deals with the effects of alcohols and ketones, two substances usually found in commercial zinc dialkyldithio‐phosphate (ZDDP), on the tribological behaviour of ZDDP. Experimental results show that two alcohol and ketone compounds, namely 2‐ethylhexanol and methyl isopropyl ketone, respectively, have an influence on the lubricity, wear resistance, and friction‐reducing properties of ZDDP. 2‐Ethylhexanol can increase the extreme‐pressure properties of ZDDP (the load‐carrying capacity of a lubricating oil being enhanced from 710 to over 1100 N). At the same time, the alcohol can also improve the wear resistance of ZDDP. However, this alcohol is detrimental to the antifriction properties of ZDDP, the friction coefficient of a lubricating oil being increased from 0. 0919 to 0. 1010. The antioxidative ability of ZDDP is weakened to some extent. The presence of a ketone, with a carbonyl group, greatly decreases the load‐carrying capacity of ZDDP, which goes down from 710 N to 597. 8 N on the addition of 1. 5 wt. % methyl isopropyl ketone to ZDDP. The mechanisms of the influence of the alcohol and ketone on ZDDP are also investigated.
Friction and wear behaviour of Sialon/ (Ca,Mg)‐Sialon with lubrication by coated PbS nanoparticles as oil additives
Authors: Zhang Wenguang , Chen Shuang , Liu Weimin , Yu Laigui 
Published: July 2006

AbstractThe friction and wear behaviour of Sialon/(Ca,Mg)‐Sialon with lubrication by liquid paraffin containing PbS nano‐particles coated with dialkyldithiophosphate or oleic acid as additives was investigated using an SRV ball‐on‐disc test rig. It was found that the addition of such nanoparticles reduced the friction coefficient of the friction couple irrespective of the concentration of the additive and the wear volume of (Ca,Mg)‐Sialon, especially under relatively high loads such as 150 N or more. X‐ray photoelectron spectroscopy and electron probe microanalysis revealed that a tribochemical film composed of PbSO4, PbS2O3, PbSO3, etc., was formed on the worn surface, and contributed to the lubricity of the PbS nanoparticles.
Tribological behaviour of S‐esters and amine salts of the O, O‐polybutoxyglycol diester of dithiophosphoric acid in mineral oil solution
Authors: Mizerski M. , Celichowski G. 
Published: July 2006

AbstractThe tribological properties of derivatives of the polyalkoxyglycol esters of dithiophosphoric acid were tested using four‐ball and ball‐on‐disc machines. Polybutoxyglycol dithiophosphoric acid derivatives were found to be effective load‐carrying additives in mineral base oil. Four‐ball and ball‐on‐disc data of some of these additives showed them to have very good antiwear/extreme‐pressure and antifriction properties. These properties were dependent upon the additive's chemical nature, concentration, sliding speed, and load. The presence of polybutoxy groups decreased the concentration of phosphorus in the additive in comparison to zinc dialkyldithiophosphates.
Improvement of antiseizure, antiwear, and anticorrosion properties of thin nitrided layers by impregnation with oil‐ or solvent‐based formulations
Authors: Iwanow J. , Senatorski J. , Tacikowski J. 
Published: July 2006

AbstractThe results of some corrosion and tribological investigations are presented in this paper. Samples with thin (white layer, WL = 16.5 μm) nitrided layers on 45‐grade steel obtained in a controlled gas nitriding process (at 570°C, 6 h; WL = 16.5 μm; grey porous zone or grey layer, GL = 6.0 μm) and impregnated by multifunctional oil‐based formulations containing BS‐MOD corrosion inhibitor (CI) as well as tribological additives (TAs) were used. The TAs when present alone (without the CI) in oil have no corrosion‐inhibiting features and also do not affect the corrosion resistance of WLs impregnated with formulations containing both the CI and TAs; corrosion resistance is mainly connected with the presence of the CI. Synergistic effects observed between TAs and the CI as well as TA concentration vs. BS‐MOD in multifunctional additives are more apparent in seizure features and wear resistance of impregnated WLs. The influence of the TAs in combination with the CI depends on their type and concentration; it can be positive or negative. Hence, the choice of composition of CI and TA for multifunctional impregnating formulations is determined, above all else, by the relation between the CI and the grade of TA. The anti‐corrosion effect as well as the tribological function is dominated by the CI component (BS‐MOD).
The influence of lubricating oil on the performance of a metal V‐belt‐type continuously variable transmission
Authors: Narita Keiichi , Deshimaru Junichi , Kato Masayuki 
Published: July 2006

AbstractThe influence of lubricating oil on the torque capacity and the efficiency of a continuously variable transmission (CVT) of metal V‐belt type were experimentally investigated using a commercial CVT unit with a belt assembly and pulley. In order to analyse the friction characteristics of each of the contacting parts in the CVT, a block‐on‐disc type friction testing machine was used. The maximum torque capacity between the belt and pulley in the actual CVT correlated with the friction coefficient under high contact pressure (200 MPa) and relatively high sliding velocity (0.1 m/s) on the friction testing machine. The transmission efficiency decreased as the load decreased. The maximum difference in the efficiency between all the commercial automotive transmission and CVT fluids tested reached 6%. It was found that the requirements for the efficiency of transmission at a lower load were in contradiction with the maximum torque capacity.