bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thick‐boundary‐film formation by friction modifier additives
Authors: Anghel V. , Bovington C. , Spikes H. A. 
Published: July 2006

AbstractThe addition of friction modifiers to lubricants has been the subject of study for a number of years. Two main models have emerged, a thick‐film and a thin‐film or monolayer model, but it is uncertain which materials and conditions produce which results. The present work, therefore, looked at whether certain additives form thin or thick films in rolling and/or rolling‐sliding contacts; the practical effect of any thick‐film formation behaviour; and the nature and structure of boundary films formed.Using ultrathin‐film interferometry, tests were performed on a rig, with two commercial friction modifiers, a copper carboxylate soap, and a dimerised unsaturated carboxylic acid, in hexadecane and in a solvent‐refined mineral oil. The results showed that both additives formed thick films in high‐pressure rolling and sliding contacts at slow speeds. However, the nature of the films is determined by temperature and speed, and under certain conditions they can be destroyed.
Friction and wear behaviour of partially stabilised zirconia in reduced pressure atmospheres containing organic compounds: Potential for process lubrication of ceramics
Authors: Sasaki Shinya 
Published: July 2006

AbstractFriction and wear tests were used to evaluate a partially stabilised zirconia (PSZ) disc rubbing against a PSZ pin in a high‐vacuum sliding tester. The surrounding atmosphere contained an organic compound vapour (either benzene, acetone, methane or methanol) at a reduced pressure. In order to understand the mechanism of the tribochemical reaction, the sliding conditions, velocity, and load were varied. During the sliding test, the friction coefficient, surface electrostatic voltage, and adsorption behaviour were measured dynamically. After the sliding test, the worn surfaces were analysed with EPMA and TOF‐SIMS to characterise the components and the molecular weight of the reaction products. The formation of sticky reaction products was observed on the sliding surface in benzene and acetone vapours. These products acted as lubricants, reducing the friction coefficients and wear rates. Analysis suggested that such sticky reaction products contained molecules up to 1000 atomic mass units (AMU).
Modern solid lubrication: Recent developments and applications of MoS2
Authors: Savan A. , Pflüger E. , Voumard P. , Schröer A. , Simmonds M. 
Published: July 2006

AbstractAn important and growing field of lubrication lies in the use of solid films, although they are in general more expensive than oils or greases, and require specialist attention both in mechanical design and in coating application techniques. In this paper, the general classification of solid lubricant types is reviewed, along with the reasons for choosing, and methods of depositing, solid lubricants, in particular MoS2. The best‐performing and most flexible technique for making MoS2 films is by physical vapour deposition (PVD), and the variants of that technology are considered. The intrinsically lubricating, lamellar structure of pure MoS2 is described, along with a brief summary of its wear and failure modes. Present applications for lubrication by MoS2 in spacecraft and dry machining are outlined, as are anti‐adhesive uses in extruding and moulding. The current state of the art of modification of MoS2 films consists in the addition of dopants (co‐sputtering), in multilayering as a series of films, each fulfilling a specific task, or in stacking repeating nano‐metre‐scale films. Composite films of MoS2 islands in a hard film matrix are also being developed.
Wear and friction behaviour of CaCO3 nanoparticles used as additives in lubricating oils
Authors: Sunqing Qiu , Junxiu Dong , Guoxu Chen 
Published: July 2006

AbstractFor some years, reports have been published on adding solid lubricant powder to oil to improve the tribological properties of the latter, but the results have not been satisfactory. In this paper, we describe the preparation of CaCO3 nanoparticles in a microemulsion consisting of sodium dodecyl‐sulphate (SDS)/isopentanol/cyclohexane/water, and assessment of the tribological behaviour of CaCO3 nanoparticles as additives for lubricating oils. The CaCO3 nanoparticles were characterised by transmission electron microscopy (TEM), and their tribological performance was tested in a four‐ball machine; the rubbing surface was analysed with X‐ray photoelectron microscopy (XPS). The results indicate that the size of CaCO3 nanoparticles increased with the concentration of aqueous reactant, and that CaCO3 nanoparticles exhibited good load‐carrying capacity, antiwear and friction‐reducing properties. The tribological properties of lubricating oils could be improved significantly by dispersing CaCO3 nanoparticles in 500SN base oil containing dispersants such as polyisobutene‐butanediimide (T154), calcium alkylsulphonate (T101) and methyl‐tricaprylamine chloride (aliquat 336). The improvements in friction and wear were concluded to be due to the formation of a film containing CaCO3 and CaO in the rubbing region, and the presence of nanoparticles, which may act in the same way as ball bearings, to facilitate sliding.
Friction modifiers in engine and gear oils
Authors: Herdan Jean M. 
Published: July 2006

AbstractReducing friction is an important target for any lubricant oil formulator. There are several ways, such as utilisation of multi‐grade oils with low viscosity at low temperature, or use of friction modifiers, to reduce friction in automotive engines and transmissions and thus save fuel. A good means to obtain an energy‐saving lubricant is by the addition of a friction‐reducing additive in a high‐range multigrade oil. This paper presents some considerations on the action mechanism of friction modifiers and the results obtained in engine and gear oils with two new nitrogen‐, sulphur‐, and boron‐containing additives.
Tribological evaluation and tribochemistry of some dialkyldithiomalonamides and their Mo‐S complexes as EP additives
Authors: Tripathi A. K. , Singh P. K. , Bhattacharya A. , Singh R. , Verma V. K. 
Published: July 2006

AbstractThe reported use of molybdenum dithiocarbamates and molybdenum dithiophosphates as antiwear and EP additives has led to attempts by the authors to synthesise certain novel Mo‐S complexes, and evaluate their effectiveness.In the present paper, the synthesis of certain 1,5‐dialkyl‐2,4‐dithiomalonamides and their Mo‐S complexes, namely, bis(1,5‐dialkyl‐2,4‐dithiomalonamido)‐dioxo‐molybdenum (VI), and the tribological evaluation of their 0.5% w/v admixtures in paraffin oil by a four‐ball test are reported, and the results compared with a dioxo‐bis(N,N‐diethyldithiocarbamato)‐molybdenum(VI) reference additive.The additive, bis(1,5‐diethylhexyl‐2,4‐dithiomalonamido)‐dioxo‐molybdenum(VI), has been found to reduce significantly both coefficient of friction and wear‐scar values, and to give higher load wear index values and flash temperatures, and has been found to be equally effective with alloy steel balls of three different compositions. However, all the Mo‐S complexes afforded smaller wear‐scar diameters in a one‐hour wear test.The wear spots on the used steel ball specimens were subjected to SEM and AES surface analysis for understanding the additive‐metal interaction tribochemistry.
Advances in solid lubrication with MoS2 multilayered coatings
Authors: Voumard P. , Savan A. , Pflüger E. 
Published: July 2006

AbstractThe general classification of solid lubricant types is reviewed, along with the reasons for choosing and methods of depositing solid lubricants, in particular MoS2. The best‐performing and most flexible technique for making MoS2 films is by physical vapour deposition (PVD), and the variants of that technology are considered. The intrinsically‐lubricating, lamellar structure of pure MoS2 is described, along with a brief summary of the wear and failure modes. Present applications for lubrication by MoS2 in spacecraft and dry machining are described. Anti‐adhesion uses in extruding and moulding are also mentioned. The current modification of MoS2 films is by addition of dopants (co‐sputtering), by multilayering as a series of films each fulfilling a specific task, or by stacking repeating nanometre‐scale films. Composite films of MoS2 islands in a hard film matrix are also being developed.
Mechanisms of wear of metal by nitrile rubber under boundary lubrication conditions
Authors: Siwei Zhang , Qiongjun Liu , Renyang He 
Published: July 2006

AbstractThe wear mechanisms for metal being worn by nitrile rubber under boundary lubrication conditions were investigated. We examined the surface profiles of both metal and rubber with SEM, and studied the chemical states of the elements in both surfaces with XPS. The functional groups in the rubber were analysed with FT‐IR. Under the action of shear forces, the metal lattice was disordered and new dislocations were formed; as a result, the chemical activity of the metal was increased. The macromolecular chains of the nitrile rubber and the alkane chains of the mineral oil were broken at stress concentration sites. These broken macromolecular chains produced active macromolecular free radicals, which reacted with the activated iron atoms and iron oxides, and generated a metal‐polymer film on the metal surface. This metal‐polymer film was destroyed and removed by the action of the debris on the sliding surface. Thus the rubber wore away the metal. Under boundary lubrication conditions with mineral oil, the physical processes of wear of T10 steel by nitrile rubber are microcutting and surface peeling.
Calcium cyclohexoxylborate: A new type of antiwear oil additive
Authors: Fenfang Li , Boshui Chen , Weijiu Huang , Diansen Gao , Junxiu Dong 
Published: July 2006

AbstractCalcium cyclohexoxylborate (CaCHOB) was prepared, and its antiwear and friction‐reducing properties were investigated on a four‐ball tester and an HQ‐1 friction machine. X‐ray photo‐electron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to determine the chemical states of the tribo‐logical species on the rubbing surfaces. The results indicate that CaCHOB demonstrates good tribological performance. XPS and SEM analyses showed that surface films containing CaO and B2O3 were formed. These films were deposited on the rubbing surface and improved the lubricating state of the friction surface.
Development of a statistical method to formulate high‐VI hydraulic oils
Authors: Neveu Christian D. , Schweder Roland 
Published: July 2006

AbstractMobile hydraulic equipment is often subjected to a wide range of operating temperatures, and so must be lubricated with oils with a high viscosity index (VI) in order to maximise efficiency. Formulating high‐VI hydraulic oils is a complex task that requires testing numerous intermediate blends in order to achieve the desired viscosity at both low and high temperatures. With the introduction of the ASTM D 6080 hydraulic oil classification, which defines a separate grade at low and high temperature for high‐VI oils, and further includes VI and viscosity measurements after the sonic shear test, formulating high‐VI hydraulic oils has become even more complex.In order to determine the most effective VI improver to meet a given set of viscosity requirements, a large statistically designed experiment has been carried out. Empirical equations have been obtained that can be used to model the blending efficiency of VI improvers at different temperatures and to estimate their shear stability. This paper shows how the results obtained for 42 hydraulic oils have been used to develop a computer program aimed at facilitating the formulation of high‐VI hydraulic oils.
Effect of mechanical shear on the thin‐film properties of base oil‐polymer mixtures
Authors: Devlin M. T. , Hammock T. , Jao T. ‐C. 
Published: July 2006

AbstractThe thickness and frictional characteristics of thin lubricant films are known to affect the fuel economy properties of oils. The base oil and polymer compositions of the lubricant are generally considered to be critical chemical factors that can influence these thin‐film lubricant properties in new oils. However, it is important to produce lubricants with good fuel economy properties that are maintained after the lubricant is degraded. Lubricants in use can undergo oxidation and mechanical shear degradation. The effect of oxidation degradation on thin‐film physical properties has previously been studied. This paper investigates the effect of mechanical shearing on thin‐film properties. Dispersant olefin copolymers are found to reduce thin‐film friction in simple mixtures and in fully formulated oils. In simple mixtures, shearing the dispersant olefin copolymers does not affect the friction‐reducing ability of these polymers. In fully formulated oils, even though shearing diminishes to a degree the friction‐reducing ability of dispersant olefin copolymers, these copolymers can still provide significant friction reduction.
Additive‐additive interactions: The search for synergistic antioxidant—antiwear phosphorodithioate compositions
Authors: Swami K. K. , Prakash S. , Mondal P. K. , Dohhen K. C. , Sarin R. , Tuli D. K. , Bhatnagar A. K. 
Published: July 2006

AbstractAdditive‐additive interactions between zinc dialkylphosphorodithioates and ashless alkylaminophosphorodithioates have been studied with the object of reducing the zinc level in the lubricant formulations. Various combinations of these components were evaluated for their antiwear and antioxidant properties using four‐ball and differential scanning calorimetry techniques.
Development of ashless multifunctional additives from cashew nutshell liquid
Authors: Swami K. K. , Prakash S. , Sarin R. , Tuli D. K. , Bhatnagar A. K. 
Published: July 2006

AbstractAminodi(alkylphenyl) phosphorodithioates have been synthes‐ised by the condensation of di (alkylphenyl) phosphorodithioic acid, which was derived from a renewable, biodegradable, low‐cost, naturally occurring vegetable product, cashew nutshell liquid, with various amines. These ashless aminodi (alkyl‐phenyl) phosphorodithioates have been evaluated as anti‐oxidant, antiwear, friction‐modifying, and extreme‐pressure additives in lubricant compositions.
Basics of mixed lubrication
Authors: Spikes H. A. , Olver A. V. 
Published: July 2006

AbstractThis paper reviews recent research in mixed lubrication, focusing on the current understanding of lubricant entrainment, and thus film thickness, and of friction in thin‐film, rough‐surface lubricated contacts. By combining research using optical interferometry on the experimental side and numerical modelling on the theoretical side, we now have a reasonable understanding of micro‐elastohydrodynamic lubrication, although design rules are still lacking. The regime of true mixed lubrication, where there are both elastohydrodynamic and boundary lubricated regions within a single contact, remains quite poorly understood. New experimental techniques as well as new information about very thin‐film rheology under high‐strain and high‐pressure conditions are probably needed before much further progress can be made in this area.
Mechanism of boundary film formation from n‐hexadecane
Authors: Makowska M. , Kajdas C. , Gradkowski M. 
Published: July 2006

AbstractIt is widely acknowledged that the process of surface film formation by tribological additives is very complex, because even saturated hydrocarbons — as major components of lubricating oils — undergo chemical changes under boundary lubrication conditions. To gain a better understanding of the tribochemical changes of paraffinic hydrocarbons, research was carried out using n‐hexadecane, which is widely used as a low‐viscosity model base oil. It has been hypothesised that the interactions between the products of n‐hexadecane triboreactions and steel surfaces are mostly initiated by the mechanical action of the system. Wear tests were performed, using a pin‐on‐disc machine. Fourier transform infrared microspectrophotometry and X‐ray photoelectron spectroscopy were used to analyse the wear tracks on the steel discs. Based on the analytical data obtained, a model of boundary film formation from aliphatic hydrocarbons is proposed.
Analysis of rough line contacts operating under mixed elastohydrodynamic lubrication conditions
Authors: Bakolas V. , Mihailidis A. 
Published: July 2006

AbstractHeavily loaded machine elements, such as gears, usually operate in the mixed lubrication regime. Surface roughness has a significant effect on the pressure distribution, the subsurface stress field, and the friction coefficient. Based on the superposition of a dry rough and a fully flooded smooth contact, a mixed lubrication model has been developed. The roughness profile is assumed to be known. Surface deformation is calculated by taking into account the pressure distribution that is built up by asperity contacts, asperity interactions, and lubricant flow. Thermal and sliding effects are incorporated into the analysis. Non‐Newtonian lubricant behaviour is considered by using a power‐law rheological model. The pressure distribution, subsurface stress field, and friction coefficient were calculated from the model at several points along the contact path for an FZG type C gear pair. It was shown that a significant part of the load is carried by the contacting asperities. The position of the maximum shear stress is very close to the surface.
Additive efficiency and micellar structure of lubricants
Authors: Bakunin V. N. , Kuz'mina G. N. , Parenago O. P. 
Published: July 2006

AbstractThis paper reports on the influence of the micellar structure of additives, for example antioxidant additives, on their performance in lubricants. It is well known that hydrocarbon lubricants have a complex liquid structure depending on the composition of the base oils and the additive packages used. The authors have elsewhere suggested a micellar inhibition mechanism that functions in cases where lubricant compositions comprise both antioxidant and detergent additives. A similar situation is created in strongly degraded lubricants when the micellar‐like structure of the hydrocarbons is due to the interaction of oxidation and degradation products. The mechanism of reverse micelle formation and its influence on the oxidation mechanism and oxidation inhibition activity of different additive types are discussed. The influence of the hydrocarbon chain length of the additives on their activity is also discussed.
Laser stimulation of the auditory nerve
Authors: Izzo Agnella D. , Richter Claus‐Peter , Jansen E. Duco , Walsh Joseph T. 
Published: July 2006

AbstractBackground and ObjectivesFor centuries, electric current has been used to stimulate neurons. Shortcomings of electrical stimulation include the contact between the stimulating electrode and the tissue, and the non‐selective stimulation of the tissue. In contrast to electric stimulation, optical radiation can provide spatially selective neural stimulation without tissue contact.Study Design/Materials and MethodsAcute in vivo experiments using gerbils were conducted to record optically evoked compound action potentials (CAPs) from the cochlea.ResultsOptical radiation evokes CAPs in normal hearing animals and in deafened animals, in which cochleae lack outer and inner hair cells. Stimulation threshold was measured as 0.018±0.003 J/cm2 (mean±SE). Laser radiation could be increased by 30–40 dB until drastic changes were seen in cochlear function. Cochlear response amplitudes to optical radiation were stable over extended stimulation times.ConclusionsWe have demonstrated that the auditory nerve can be stimulated by optical radiation. One potential clinical use of this technology would be for cochlear implants. Lasers Surg. Med. 38:745–753, 2006. © 2006 Wiley‐Liss, Inc.
Chain Orientation in Polyethylene Fibers Prepared by Ethylene Nanoextrusion Polymerization
Authors: Ye Zhibin , Zhu Shiping , Britten James F. 
Published: July 2006

AbstractSummary: Ethylene nanoextrusion polymerization has been demonstrated to be a novel nanofabrication concept for the preparation of polyethylene (PE) fibers directly from ethylene monomers without any post‐processing procedures. For PE fibers, chain orientation is a critical parameter that affects performance and application of the fibrous materials. In this communication, we report an investigation on chain orientation in PE fibrous samples prepared through nanoextrusion polymerization using a two‐dimensional wide angle X‐ray diffraction (2D WAXRD) technique. Two types of fibrous samples, including individual microfibers and microfiber aggregates, were sampled randomly and studied. For individual PE microfibers, anisotropic diffraction patterns were observed, suggesting chain orientation along the microfiber axial direction. Some microfibers showed the most desired diffraction pattern often found in high‐modulus high‐strength PE fibers. These samples possessed a very high degree of chain orientation along the fiber axis. Owing to a random aggregation of anisotropic microfibers, microfiber aggregates exhibited isotropic diffraction patterns. This work provided further experimental evidence for the proposed nanoextrusion polymerization concept.2D WAXRD diffraction pattern of a PE microfiber.magnified image2D WAXRD diffraction pattern of a PE microfiber.
New heuristic methods for the capacitated multi‐facility Weber problem
Authors: Aras Necati , Altınel İ. Kuban , Orbay Metin 
Published: July 2006

AbstractIn this paper we consider the capacitated multi‐facility Weber problem with the Euclidean, squared Euclidean, and ℓp‐distances. This problem is concerned with locating m capacitated facilities in the Euclidean plane to satisfy the demand of n customers with the minimum total transportation cost. The demand and location of each customer are known a priori and the transportation cost between customers and facilities is proportional to the distance between them. We first present a mixed integer linear programming approximation of the problem. We then propose new heuristic solution methods based on this approximation. Computational results on benchmark instances indicate that the new methods are both accurate and efficient. © 2006 Wiley Periodicals, Inc. Naval Research Logistics 2006