bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new test technique for the laboratory evaluation of energy‐efficient engine oils
Authors: Babu A. V. Suresh , Martin V. , Mehta A. K. 
Published: July 2006

AbstractTesting lubricants for fuel economy is a significant part of the drive for energy conservation. Generally, the small differences in fuel economy between lubricants make measurements inherently uncertain. Furthermore, precise engine tests for assessment of energy efficiency are expensive and time consuming. There has been a need, therefore, for the development of an effective laboratory screening technique to assess the energy efficiency of engine oils. With this objective in view, a new test technique consisting of two different tests has been developed for measuring lubricant‐related fuel economy.Fuel economy through the use of engine oil is achieved by reducing boundary friction and viscous friction. Whereas reduction in boundary friction is obtained through the use of friction modifiers in engine oil, viscous friction is reduced through the use of low viscosity oils and by multigrading.The efficacy of action of friction modifiers in reducing boundary friction has been assessed with a SRV‐Oscillating Friction and Wear Tester, using point and piston ring/liner segment contact. For the measurement of viscous friction, an attempt has been made to find out the reduction in viscous friction by using low viscosity oils and multigrade oils on a SAE No. 2 Machine, with all‐steel clutch plates.
Studies on the tribological behaviour of two oil‐soluble molybdenum compounds under reciprocating sliding conditions
Authors: Gondal A. K. , Sethuramiah A. , Prakash Braham 
Published: July 2006

AbstractThe use of oil‐soluble organo‐molybdenum compounds in engine oils can help in fuel conservation by reducing engine friction and increase durability by improving wear characteristics. The tribological behaviour of molybdenum dialkyldithiophosphate (MoDDP) was studied with a SRV Optimal tester under reciprocating sliding conditions. The studies were conducted under nonconformal contact conditions on En‐31 steel and conformal contact conditions on piston ring and liner materials. The results indicated that the frictional behaviour of these additives is shear sensitive. Shear sensitivity is influenced by materials, operating conditions and the interaction of MoDDP with additives present in the oil. MoDDP when used in base oil was found to increase the scuff resistance of ring and liner materials. The use of the additive reduced friction and wear (running in as well as normal) under nonconformal contact conditions, while under conformal contact conditions its effect was selective and limited.
A study of tribopolymerisation under fretting contact conditions
Authors: Kajdas C. , Lafleche P. M. , Furey M. J. , Hellgeth J. W. , Ward T. C. 
Published: July 2006

AbstractThe present study is aimed at determining whether or not tribopolymerisation can occur under conditions of fretting contact. Using a high contact stress system consisting of oscillating metal balls loaded against flat steel discs, effects of various monomers on friction, wear, and surface film formation were determined. Monomers were used at 1% concentration in hexadecane. Under the conditions used (90N load, 40 Hz frequency, 300 μm amplitude, for 1 hour), the monomers tested reduced friction or wear or both. Fourier Transform Infrared (FTIR) analysis of the test specimens showed that organic material is presented in the wear scars and depends on the metal system used, the monomer structure, location within the track, and the method of cleaning the surface after a test. With Al‐on‐steel, the addition of 1% styrene to hexadecane reduced volumetric wear of the disc by 65%; furthermore, positive FTIR evidence of polystyrene in the wear track was obtained. But adimer acid/glycol monomer formed metal soaps, no polymer, and had little effect on wear under these conditions. These results support the hypotheses that addition‐type tribopolymerisation can be initiated by exoelectron emission. Additionally, it was found that not only does methyl methacrylate polymerise under the fretting conditions, but the polymer film formed also reacts with the friction contact surface.Taken as a whole, the results of this study of possible tribopolymerisation under fretting conditions support both major hypotheses, namely that: (i) for condensation‐type monomers, the most important factor is the temperature of the rubbing surfaces. (ii) For addition‐type monomers, it would appear that the effect of exoelectron emission can initiate surface polymerisation even at relatively low surface temperatures, e.g., 10–40°C above ambient. This is in agreement with the negative‐ion‐radical action mechanism (NIRAM) of boundary lubricant component.Finally, the results obtained in this study demonstrate that the principle of tribopolymerisation developed by Furey and Kajdas can be used as a novel and effective approach to designing specific molecular structures for boundary lubrication under various rubbing conditions.
Tribological, electrochemical, and spectral analysis of zinc dialkyldithiophosphates (ZDDP) of different thermal stabilities
Authors: Likhterov S. D. , Fufaev A. A. , Kotova G. G. , Shor G. I. 
Published: July 2006

AbstractThe antiwear properties of five zinc dialkyldithiophosphates, which differed in thermal stability, were evaluated in a 4‐ball machine by a preliminary wear track formation method. After testing the additives, the wear resistance of the films formed was measured by the increase in preliminary wear scar diameter over that of the additive‐free oil. IR spectroscopy was then used to study the transformation products of additives after thermostatic testing at between 100 and 240°C on steel surfaces, where the interaction products were evaluated by electrode potential method. The interaction of the decomposition products of dithi‐ophosphates with metal surfaces was found to be followed by a change in electrode potential. For the tested additives, a relationship is shown between antiwear effectiveness of the film on a friction track during tribological tests and the electrode potential value of the steel sample. Different parts of the relationship between the electrode potential and temperature relate to different stages of dithiophosphate decomposition measured by IR spectroscopy. It can be said that chemical modification of the steel surface which produces an improvement of antiwear properties, starts at the decomposition temperature of the dithiophosphate neutral salt.
A study of viscometric properties of multigrade lubricants
Authors: Hassanean M. H. M. , Bartz W. J. , Naga H. H. Abou El 
Published: July 2006

AbstractThe rheological behaviour of several multigrade oils formulated with four different polymer‐type viscosity index (VI) improvers was experimentally studied at different shear rates ranging from 1000S−1 to 35,000S1 and at both VI reference temperatures of 40°C and 100°C. The investigation was an attempt to assess the effect of each polymer addition on the viscosity‐temperature relationship, as related to its chemical type and to the shear rate applied. It was found that the viscosity loss with increasing shear rate is greater for hydrocarbon polymer types than for methacrylate, especially at low temperatures. It was also found that the viscosity index is affected by the shear rate as well as by the type and concentration of polymer additive; its significance is thus linked with the condition under which it is determined and cannot be used as an absolute criterion for the appraisal of multigrade oil performance.
Effects of NOX on inhibition of oxidation by ZDTPS
Authors: Johnson M. D. , Korcek S. , Rokosz M. J. 
Published: July 2006

AbstractInvestigations of the effects of nitrogen oxides (NOX) on liquid phase oxidation and inhibition have been conducted in order to develop an improved understanding of the processes by which NOx accelerates oil degradation in internal combustion engines. Results from studies of the effects of NOx on oxidation of hexadecane (HD) alone, and in combination with a radical trapping (hindered phenol) antioxidant, and preliminary studies with zinc dialkyldithiophosphates (ZDTPs) were presented in previous reports.1‐3 The complexity of reactions involving NOx and the role in lubricant degradation of NOx from blowby were described. Those results suggested that NOx accelerates the rate of consumption of antioxidant additives and, thus, shortens the useful life of the oil. This work describes results of additional investigations with ZDTPs.
An approach to the study of elasto‐plastohydrodynamic lubrication in the wire drawing process. Part 2: Theoretical predictions
Authors: El‐Butsh A. M. A. , Ei‐Badrawy R. S. , Mokhtar M. O. A. 
Published: July 2006

AbstractThe generalised Reynolds' equation for Newtonian and non‐Newtonian fluids, as applied to the wire‐drawing process, together with the plasticity and energy equations have been adopted in solving the elasto‐plastohydrodynamic lubrication problem in the wire‐drawing process. The equations have been solved numerically using a finite difference technique with Gauss‐Siedel iterative scheme to predict hydrodynamic behaviour and to correlate the forming parameters to the lubrication behaviour in an endeavour to find the optimum operating conditions for maximum precision and productivity. The effect of using either Newtonian or non‐Newtonian lubricants on the process parameters has been also studied, to predict the most suitable lubricant type.The results indicate that the increase in the flow behaviour index increases the pressure gradient in the work zone, with a consequential reduction in oil film thickness. Also the minimum film thickness is highly influenced by the drawing speed.It can be concluded that the isothermal solution renders lower drawing stress than the adiabatic solution. The maximum shear stress, and hence the power loss, increases with the increase in die convergence angle.
The study and application of an anti‐adhesive wear lubricant for use in deep drawing
Authors: Hu X. , Xiang F. 
Published: July 2006

AbstractThis paper reports on an anti‐adhesive wear lubricant (NL2) used in deep drawing, containing as additives B, N compounds and zinc (cyclic) polymethylenedithiophosphate. It covers the synthesis of these additives, their properties, and the friction and wear mechanism of NL2 in the deep‐drawing process. These are studied by means of a strip bending drawing tester, a four‐ball tester, and IR, SEM, and EDAX analysis. The results show that the new additive gives good adhesive wear protection in deep drawing.
Visualisation of fuel‐lubricant interaction on the cylinder surface in the combustion chamber of SI engines
Authors: Kovács A. 
Published: July 2006

AbstractVisualisation of fuel component penetration and release into the lubricating oil layer covering the combustion chamber wall has been achieved, using a laser‐induced fluorescence (LIF) test technique. Experimental data show that fuel component penetration into the oil layer contributes not only to unburnt hydrocarbon emissions in spark ignition (SI) engines, but also to engine oil degradation. Fuel components accumulated in the oil layer are transferred to the bulk in ring belt zones, after a measurable residence time. A significant difference in film thickness between the oil layer on the combustion‐chamber wall during the intake/compression sequence, as against the expansion/exhaust sequence, indicates that in the ring belt zones and above, engine oil viscosity, and hence load‐carrying capacity, is influenced by fuel absorption/desorption in the engine oil.
A study of the tribological properties of some 1,3,4‐thiadiazole type lubricant additives
Authors: Cao Lin , Wei Dan‐Ping , Wang Rulin 
Published: July 2006

AbstractThe synergistic effects between the group containing S and P, hydroxyl group and a 1,3,4‐thiadiazole ring in the same molecule have been studied by investigating the tribological properties of three 1,3,4‐thiadiazole derivatives. The possibility of predicting properties of additives from their chemical structures is discussed. The results indicate that introducing a long carbon chain with a hydroxyl group (LCCWHG) into the side chains of a 1,3,4‐thiadiazole ring can effectively enhance its antiwear ability and that dimercaptothiadiazole adduct of dialkyl thiaphosphoric acid (DAODTA) can have good extreme pressure performance and excellent antiwear properties.
The tribological properties and action mechanism of Schiff base as a lubricating oil additive
Authors: Wan Yong , Liu Wei‐Min , Xue Qunji 
Published: July 2006

AbstractIn this paper, an organic compound containing a nitrogen element, Schiff base, is synthesised, and its tribological characteristics are evaluated by four‐ball and Timken machines. Schiff base possesses friction‐reducing and antiwear properties, especially under low load. Results from X‐ray photoelectron spectroscopy (XPS) reveal that the binding energy of N1s increases in the boundary film. Differential thermal analyses (DTA) indicate that Schiff base reacts with iron powder, forming complex compounds through hydroxy and azomethine. An action mechanism, with surface‐complex compound films being formed on the surface, is proposed.
Microtribology, squeeze, and friction of the colloidal layer
Authors: Mazuyer Denis , Tonck Andrél , Georges Jean‐Marie , Loubet Jean‐Luc 
Published: July 2006

AbstractLubricant films containing colloidal overbased calcium salts have particular effects on detergency and on the wear process. The mechanical properties of such boundary films are very dependent on the process conditions, and are essentially a result of physico‐chemical transformations of the colloid. Three types of films were compared: a film obtained by the drying of the base solvent, a film due to the compaction of the colloid between two steel surfaces, and a friction film obtained with this type of lubricant. Adsorption, compaction, and shear transformations induce a solid film.The pressure effect on the frictional behaviour of these colloidal films has been investigated using a surface force apparatus for low contact pressure (104 to 106 Pa), and using tribometers supporting heavy loads for the analysis of the high pressure domain. Above a critical pressure, evaluated at 106 Pa, the colloidal film does not flow, but forms a compacted mattress sliding on the surface plane and squeezing a molecular layer of lubricant.
Influence of aldehydes in make‐up oils on antioxidation properties
Authors: Minami Ichiro 
Published: July 2006

AbstractThe addition of more antioxidant to aged oils is not always effective in preventing autoxidation. To investigate this phenomenon, a solution of antioxidant and model oxide in hexadecane was examined by means of the induction period method. Aldehydes were found to be the most active species for reducing the antioxidation properties of zinc dialkyldithiophosphate (ZDTP), 2,6‐di(tert. butyl)‐4‐methylphenol (DBPC), and N‐phenyl‐1‐naphtylamine (PNA). Carboxylic acids, ethers, alcohols, and ketones to some extent reduced the induction period with these antioxidants. Esters showed almost no influence on reducing their antioxidant properties.Reaction of ZDTP with aldehyde was studied by means of 31P‐NMR analysis. It was found that (a) aldehydes accelerate conversion of ZDTP, and thereby reduce its antioxidant performance. (b) Conversion of ZDTP in the presence of aldehydes under oxygen at 130° in hexadecane and no reaction was observed under nitrogen at the same temperature. Active intermediates derived by the autoxidation of aldehyde were suspected. (c) Reaction of peroxycarboxylic acid with ZDTP took place smoothly at 0°C under nitrogen to give bis(dialkylthiorophosphoro)disulphide and the corresponding carboxylic acid. Reaction of hydroperoxide with ZDTP took place at room temperature to give oxo‐hexa(dialkylphosphorothiorothionato)‐tetrazinc.Two mechanisms for decomposition of ZDTP promoted by aldehydes, namely hydroperoxide and peroxycarboxylic acid mechanisms, are proposed. Reaction of peroxycarboxylic acid with DBPC or PNA barely took place at room temperature: for these antioxidants, the peroxycarboxylic acid mechanism would be excluded. Radical species derived by the autoxidation of aldehydes were considered as active intermediates.It is considered that classification of the types of oxides that exist in used oils in the key to optimising the effect of re‐added antioxidants.
An investigation into the antiwear, antioxidation, and anticorrosion behaviour of some derivatives of 2,5‐dimercapto ‐1,3,4‐thiadiaxole
Authors: Wei Dan‐Ping , Cao Lin , Wang Lu‐Lin 
Published: July 2006

AbstractIt appears that the comprehensive performance of 2,5‐dimercapto‐1,3,4‐thiadiazole derivatives is dependent upon both the type and the structure of the chains attached to the carbon atoms in the 2 and 5 positions of the thiadiazole ring. For the side chain of the monosulphide type R‐S‐, the type and location of substituents have an important influence on additive performance. In the case of the side chain of the disulphide type, X‐SS‐, the presence of the phosphorus‐containing group has a significant effect on multifunctionality.
Local order in surface ZDDP reaction films generated on engine parts, using EXAFS and related techniques
Authors: Belin M. , Martin J. M. , Tourillon G. , Constans B. , Bernasconi C. 
Published: July 2006

AbstractThe study of reaction films generated in a mild wear lubricated process remains a topic of interest. We present in this paper the latest results obtained by the structural analysis of reaction films directly on friction surfaces. An experimental engine setup is used, in which a cam and follower system is externally driven without combustion. The system is lubricated with a base oil containing ZDDP (zinc dialkyl‐dithiophosphate). After the wear test, the engine parts are analysed by the EXAFS technique (Extended X‐Ray Absorption Fine Structure) in the Total Electron Yield configuration. It is found that the build‐up of the film greatly depends on the formulation of the lubricant, and on the test conditions. In the film formed with ZDDP, the initial Zn‐S bonding changed to ZN‐O in a completely amorphous arrangement. The nature of the wear debris is found to be very similar to the surface of the reaction film. These results are discussed in terms of microscopic wear mechanisms.
Piston ring friction loss behaviour for motored and fired reciprocating engines
Authors: Ting L. L. , Shih T. S. 
Published: July 2006

AbstractA previously developed piston ring lubrication model has been further extended so that the piston ring frictional losses can be predicted in both hydrodynamic lubrication and metal‐to‐metal contact regions for various engine operating conditions. Ring friction results for two engine types are presented for both hot motoring and engine firing conditions. The hot motoring predictions were found to be in good agreement with tests. Results show that when the engine is motored, piston ring friction losses in the hydrodynamic lubrication region predominate. If the engine is fired, the losses in the metal‐to‐metal contact region become dominant due to high gas pressure and temperature effects. Ring friction loss can be significantly reduced by using low tension rings with a correct ring sliding face profile.
Effect of applied voltage on friction and wear characteristics in mixed lubrication
Authors: Yamamoto Yuji , Ono Bunji , Ura Akira 
Published: July 2006

AbstractThe effect of an electric field applied between rubbing surfaces on friction and wear characteristics was examined using a ballon‐disc testing apparatus under different lubrication conditions. The lubrication conditions were changed by changing the viscosity of the lubricants. By applying an electric field between the rubbing surfaces, the oxidation of the rubbing surface at the anode side is enhanced, and suppressed on the cathode side surface. The oxide film formed on the anode surface being harder than the bulk steel, the rubbing surface at the anode side was little worn, but that at the cathode side was abrasively worn. This wear characteristic could be utilised to attain favourable running‐in. The application of an electric field, however, is considered to promote the breakdown of any EHL film formed. Therefore the effect of the application of an electric field between rubbing surfaces is influenced by the lubrication condition that is being tested.
Zinc oxythiomolybdate (ZnMoO2S2) powder as a solid lubricant for high‐temperature rolling contact applications
Authors: Trivedi Hitesh K. , Gerardi David T. , Rosado Lewis 
Published: July 2006

AbstractConventional liquid lubricants being used in today's gas turbine engines will not be able to operate effectively in the hostile bearing environments expected in future turbine engines. The expected high operating temperatures (500–800°C) mandate new and innovative lubrication schemes to achieve success. Recent studies have demonstrated that a new class of solid lubricants, the complex chalcogenides or metal ocythiomolybdates, have good potential for high temperature lubrication. This paper describes the friction, wear and rolling contact endurance of three high‐temperature bearing materials using a zinc oxythiomolybdate (ZnMoO2S2) powder lubricant. Rolling contact tests were conducted using VIM‐VAR M50, micromelt T15 tool steels and silicon nitride (Si3N4) at temperatures ranging from 23°C to 649°C, using a modified ball‐on‐rod type rolling‐contact fatigue tester. Significant improvements in friction, endurance and wear were observed at all test temperatures, and with all three materials evaluated, when ZnMoO2S2 was used as a lubricant. Overall, silicon nitride exhibited the best frictional and antiwear performance. The lubricant powder exhibited the best tribological performance with T15 and M50 specimens between 177°C and 316°C. Energy Dispersive X‐Ray Analysis (EDAX) of wear tracks showed the presence of iron (Fe) on the Si3N4 specimens as well as the presence of zinc (Zn) on both the T15 and the M50 specimens.
Observation of microdispersed particles in overbased detergents
Authors: Fu X. G. , Li S. B. , Zhang J. H. 
Published: July 2006

AbstractThe results of electron microscopic determination of the colloidal structure of some typical lubricating oil detergents by an improved freeze‐etching method for specimen making are reported. The work establishes that the improved freeze‐etching technique provides a reliable means for observation of colloidal structure of detergents, where the conventional method does not.
Definition of the transition from fluid lubrication to mixed lubrication for rough surfaces
Authors: Liu K. , Liu X. J. , Xie Y. B. 
Published: July 2006

AbstractFluid lubrication and mixed lubrication can both be phenomena in the study of the lubrication of rough surfaces. In this paper, we take the surface as random process and, by studying the contact of surfaces which present roughness, we can put forward a method which defines the transition from fluid lubrication to mixed lubrication, by looking for the first contact point between the two surfaces. This study suggests that the transition between fluid and mixed lubrication relates to the number of asperities on the contacting surfaces, an advance on former methods. We also apply this method to piston ring/cylinder lubrication research. The results show that the transition changes with time.
The synthesis and antiwear action of tungsten dithiolate
Authors: Rengen Xiong , Junxiu Dong 
Published: July 2006

AbstractTungsten dithiolate was synthesised by the reaction of WO3 with toluene‐3,4‐dithiol (abbreviated to H2TDT), and its extreme‐pressure and antiwear properties were investigated on a four‐ball tester. The results showed that it possesses fairly good extreme‐pressure and antiwear abilities. Based on analytical results obtained by Scanning Auger Microprobe and Scanning Electron Microscopy, as well as Electron Ionisation Mass Spectra fragments, the antiwear mechanism of WTDT suggested that a permeating layer containing WC, WS2, and WO3 played an important role in the antiwear and friction‐reducing action.