bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of oil analysis and filter content analysis: A case study
Authors: Toersen H. , Slob P. A. A. 
Published: July 2006

AbstractOil filters contain useful information on wear that has occurred in the oil‐wetted mechanical system. However, filter analysis for wear detection is seldom performed, because the method is fairly cumbersome. On the other hand spectral oil‐analysis can be economically done in highly automated laboratories and is therefore widely accepted.This paper describes the case involving a small passenger car diesel engine, where the results of the filter analysis were compared with the results of simultaneously performed oil analysis using X‐ray fluorescence. Oil and filter samples were analysed after each 10,000 km, when oil and filter changes took place, over the life of the engine to 165,000 km.The results, as derived from the filter samples, showed a roughly shaped bath‐tub curve development of the wear rate before the final stage of serious deterioration. However, the oil analysis did not confirm this trend. It is believed that the different in characteristics between a filter sample and an oil sample, and the effects of particle size and of oil filtration on the oil sample, may cause this discrepancy. If the latter is the case, care has to be taken in oil sampling for wear analysis, particularly in systems with fine full‐flow filtration.Suggestions are made at the end of the paper for the design of dedicated diagnostic filters for wear debris detection.
A laboratory study of friction in hip implants
Authors: Levitin Michael , Shamshidov Boris 
Published: July 2006

AbstractOne of the most promising methods of reducing wear and extending the useful life of artificial joints is by regular microrelief treatment, a novel finishing technology based on the formation of a system of fine grooves by means of plastic deformation of surfaces with a ball‐tipped diamond. Laboratory friction testing of treated joint prostheses is an essential component in the developmental process of this application. In order to evaluate the friction characteristics of hip prostheses made up of metal ball heads treated with regular microrelief, a computer‐monitored friction tester was developed. The ball head was pressed against the cup by a load. The friction torque was measured by means of a load cell. Distilled water was used as the lubricant. Before the friction test, all balls were tested in a specially developed wetting ability tester, to evaluate the effect of regular microrelief treatment on the wetting behaviour of the head surface in water. The results obtained showed that the wetting ability of balls treated with regular microrelief was higher by 30% as compared with non‐treated hip heads. The articulating pairs with heads treated with regular microrelief showed a 25–35% reduction in the friction torque, when compared with conventional, non‐treated joints.
Experimental evaluation of the influence of macro circumferential residual stress on the wear resistance of some metals
Authors: Özmen Yilmaz 
Published: July 2006

AbstractTo investigate the effect of residual stress on the wear resistance of metals, macro circumferential residual stresses σI were modelled as externally applied stress, below the yield stress of the material because residual stress cannot exceed yield stress, with a special apparatus. In order to compare the effect of residual stress on wear resistance, three different stress levels were applied to each specimen, 0 Re, 0.5 Re, and 0.8 Re. A full programme of testing under all combinations of factors would be very expensive and time consuming, so, in the present case, all the other factors were fixed at constant values, while the chosen factor was varied in a controlled way in a series of tests. There has been no universally accepted theory or law on the effect of residual stress on wear resistance. In this study, the wear results for dry wear tests in terms of residual stress applied mechanically to specimens were very difficult to interpret.
A test method to investigate the tribological behaviour of friction materials under ultrasonic fretting conditions
Authors: Rehbein Peter , Wallaschek Jörg , Löhe Detlef 
Published: July 2006

AbstractTo investigate and understand the tribological behaviour of high‐frequency tribosystems such as ultrasonic motors, a specific test method is necessary. This work reports on the construction of a test machine to evaluate the friction and wear behaviour of friction materials under ultrasonic fretting conditions, as well as giving some representative experimental results. Hard/soft (steel/polymer) and hard/hard (steel/alumina, alumina/alumina) couples were studied with respect to their application as contact materials in ultrasonic motors. Investigation of friction behaviour at high frequencies showed that friction‐induced vibrations lead to friction forces of much lower magnitude than predicted by quasistationary friction coefficients obtained for sliding friction. The wear behaviour is characterised by abrasive, adhesive, fatigue and oxidative mechanisms, depending on the mating materials. For polymeric friction materials, the influence of fibre reinforcement and the incorporation of PTFE as a solid lubricant were evaluated. The presence of PTFE resulted in a strong improvement of both friction and wear behaviour.
Evaluation of the low‐temperature performance of engine lubricants using the scanning brookfield viscometer
Authors: Kinker B. G. , Souchik J. M. , Neveu C. D. 
Published: July 2006

AbstractWhen subject to low‐temperature conditions, the paraffins in a lubricant come out of solution to form structures that can impair oil flow. The size of the paraffinic crystals, and the strength of the three‐dimensional network they form, depend on physical parameters, such as temperature, cooling rate and soaking time, as well as on the chemical nature of the wax and of other components in the oil.To evaluate the ability of lubricants to flow under low‐temperature conditions, a number of test methods have been developed, from the simple pour‐point test (ASTM D‐97), to very sophisticated tests such as the MRV TP‐1 (ASTM D‐4864). In the early 1980s, a new technique, using the scanning Brookfield viscometer (ASTM D‐5133), was developed. This method has progressively gained acceptance by industry and is now part of the ILSAC GF‐2 specification. The scanning Brookfield technique provides a new approach to continuous measurement of the viscosity of engine lubricants at very low shear rates, with decreasing temperature. It is said to be unique in its ability to identify oils which develop gel structures at low temperature.After presenting background information on the scanning Brookfield viscometer, this paper examines its use with modern engine lubricants, and its ability to evaluate the effect of pour‐point depressants on the low‐temperature performance of engine lubricants.
Diffraction methods in tribosystem diagnostics
Authors: Garbar I. I. , Sher E. 
Published: July 2006

AbstractIn this paper, two structural analysis methods, X‐ray diffraction and electron diffraction, are considered for their use in tribosystem diagnosis. It is shown that, for certain applied tribological problems, such as determination of friction conditions and type of wear regime, estimation of running‐in period, selection of optimum wear‐resistant materials, and of suitable conditions of friction and wear, these methods can be used in addition to more conventional tribotesting and tribodiagnostic methods.A study of the structure of certain friction pair materials and wear particles was conducted. X‐ray investigations of the surface layers of the friction pair materials showed that structural characteristics, such as broadening and intensity of diffraction lines, can be used in the estimation of friction conditions. Examples of the choice of structurally wear‐resistant engineering materials, and of suitable friction conditions, are given. The study of wear particles produced under different friction conditions shows that these particles vary not only in form and dimensions, but also in phase composition. This provides important additional information for friction and wear process diagnostics. The method involves electron diffraction analysis of isolated wear particles, which allows us to characterise the wear processes under friction conditions. It is shown that a definite phase composition, the fineness of wear particles, and the quantitative ratio of each of the wear product phases, can be characterised for different wear types. Some useful applications of these investigative methods for analysis of the wear nature of friction pairs are described.
Development of a high‐vacuum wear test apparatus mounted in a scanning electron microscope
Authors: Lacey P. I. , Naegeli D. W. 
Published: July 2006

AbstractThe lubrication of sliding components in vacuum conditions offers unique challenges. High vacuum precludes the use of many conventional liquid lubricants because of vaporisation, while the lack of a naturally‐occurring oxide film on metal surfaces may cause instant seizure following the failure of a lubricant. Solid lubricants, such as molybdenum disulphide and tungsten disulphide, are also used, but are less effective than more complex liquid lubrication mechanisms. New surface treatment processes, such as diamond‐like carbon (DLC), are becoming available and may further reduce wear. The purpose of the present paper is to describe an apparatus that can evaluate solid lubricants under a wide range of contact conditions at vacua down to 3 × 10−7 Torr. The wear test stage is mounted in the chamber of a Scanning Electron Microscope (SEM), which allows real‐time high magnification photography of the contact area. The complete stage may be moved in three planes to facilitate observation of the complete contact area. Realtime measurement of applied load and friction coefficient is also provided.
Development of dispersivity tests for gasoline and diesel engine lubricants
Authors: Diraison C. , Bourgognon H. , Abellaneda G. 
Published: July 2006

AbstractOne of the aims of the Groupement Français de Coordination (GFC, branch of CEC), and their working group LM2, is to develop laboratory tests to forecast dispersivity problems for new lubricants, both gasoline and diesel. This paper looks at the development of a spot test for forecasting dispersivity, allowing correlations to be made with reference oils used in the M102E test (gasoline), and the XUD 11 ATE test (diesel). Various round robins were undertaken to establish the relative importance in terms of influence of various factors, including spot storage temperature, paper batch, and quantity of deposited oil. The work has resulted in recommendations as to method and materials.
CVT lubrication: The effect of lubricants on the frictional characteristics of the belt‐pulley interface
Authors: Watts Raymond F. , Richard Katherine M. 
Published: July 2006

AbstractTwo tests for evaluating continuously variable transmission (CVT) lubricants have been developed using readily available test equipment and test parts. These tests have been designed to rank lubricants using a number of criteria relevant to the performance of the lubricant in a push‐belt variator. These include overall level of friction, friction stability, temperature dependence of friction, and load dependence of friction. Testing lubricants of different types has shown the effect of lubricant chemistry on the parameters measured and indicates that some existing fluids, a CVT fluid and passenger car motor oil, as well as an experimental fluid, should give good performance in a continuously variable transmission using a push‐belt variator.
Friction and wear behaviour of hard coatings in vibrating contacts
Authors: Skopp A. , Klaffke D. 
Published: July 2006

AbstractThe friction and wear behaviour of thin hard coatings, such as TiN and the promising class of C‐based coatings (a‐C, a‐C:H, and diamond for example), are compared under oscillating and reciprocating sliding conditions. The typical effects of test parameters, such as stroke, frequency, normal force, relative humidity and test duration, are described as a basis for the proper selection of test conditions or, conversely, for the selection of suitable coatings for particular practical applications.Friction and wear data from over 1000 vibrating tests using thin hard coatings against 100Cr6 and against Al2O3 have been compiled in a database. This allows easy manipulation and comparison of test results. Using selection criteria and filter procedures (e. g., lifetime of coatings, friction limits, and critical wear rate), suitable coating systems for different test conditions can be chosen from the database. The effects of test parameters on friction and wear behaviour and changes have anyway to be known for meaningful tribotesting, as well as for the selection of coatings.
Measurement of the temporary shear stability of lubricants in a gear pump
Authors: Bielmeier E. , Bartholomae I. , Neveu C. D. 
Published: July 2006

AbstractIn specially designed test equipment, consisting of a hydraulic pump loop capable of measuring oil flow rate for given output pressures, the authors have shown that increased output pressure results in an actual decrease in flow rate, this decrease being linear. It is concluded that some ‘leakage’ takes place between the gears and the pump housing, which increases when decreasing the oil velocity, for a given output pressure and temperature. Models are presented which provide a good representation of internal leakage observed in practical tests of various fluids.
DSC as a valuable tool for the grease laboratory
Authors: Josef Pohlen Martin 
Published: July 2006

AbstractThere is a need to reduce both the time and cost involved in research and development for lubricating greases. Most of the normal test methods used to characterise a grease are long‐term tests, but it is important to develop screening tests that also give reliable information. Thermal analysis is one such way to fulfil these requirements. In the present work, a differential scanning calorimeter (DSC) with a normal pressure cell was used in a grease laboratory. By varying the atmosphere and the heating rate, different tests were worked out. The effects of changing physical parameters, such as viscosity and thickener structure, or chemical parameters, such as additives and thickener types, were examined. These methods can be used for controlling raw materials, improvement of grease formulations and production processes, development of new products, as a replacement for the oxidation bomb (ASTM D‐942, DIN 51 808), and as a screening test for the FE9 life (DIN 51 821) test rig.
The influence of contact geometry on friction and wear characteristics
Authors: Michalczewski R. , Piekoszewski W. , Szczerek M. , Wiśniewski M. 
Published: July 2006

AbstractThis paper describes some results of evaluating the influence of contact geometry on tribological characteristics. Friction characteristics obtained for a distributed contact (pin‐on‐disc and block‐on‐ring), a linear concentrated contact (pin and vee‐block and block‐on‐ring) and a point concentrated contact (ball‐on‐disc and three cylinder‐cone) are presented. The wear scars were analysed using scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The results show different values of friction and wear coefficients for the different types of contact geometry. The paper also assesses the effect of non‐test characteristics, e. g., vibration.
An investigation into the surface fatigue of materials and thin layers using a sliding diamond spherical segment
Authors: Iliuc Ivan , Jumolea Alina 
Published: July 2006

AbstractMethods for testing the surface fatigue of materials or thin layers normally involve configurations with two or more rolling balls or discs. Such equipment and test specimens are quite complicated, and for a large number of experiments, costly. Testing could be considerably simplified if the stressing of the material surface were performed with a sliding natural diamond spherical segment. A diamond on steel (or any different material) friction pair has the particular attribute that sliding wear is absent. Under these circumstances, after a certain number of strain cycles, fatigue failure of the investigated surface or layers appears. A particularly relevant application is investigation of the adhesion of a DLC layer.
Major pathways for used oil disposal and recycling. Part 2
Authors: Kajdas Czeslaw 
Published: July 2006

AbstractOne of the main concerns with lubricating oil relates to used oil management for both industrial and engine oils, although the environmental impact of gasoline and diesel engine oils is the most critical. Provided that efficient management systems are in place, most used oil should not reach the environment, so, the major question is ‘how should we dispose of collected used oil?’ The first option lies in burning it as a fuel, the second in recycling (re‐claiming, reprocessing, re‐refining). The latter allows recovery of mineral base oils, which are valuable constituents of crude oil.In the first part of this paper, the author looked at the problems associated with used oil, its use as a fuel, and simple recycling. He went on to look at major re‐refining processes, starting with hydrogenation (KTI, Mohawk, BERC/NIPER, and PROP technologies). In Part 2 he covers other processes, including Safety Kleen, IFP/Snamprogetti, UOP Hylube, and vacuum distillation and clay treatment technologies.
Developments in tribological materials in the next millennium
Authors: Santner E. 
Published: July 2006

AbstractThe materials needed for tribological contact systems in the next millennium will depend on the trend and pace of technological development, and environmental policy. The latter will certainly demand lower pollution and energy consumption, so materials should preferably be light, and work in most friction systems without lubrication, but with low friction, and no wear. The following properties, or requirements, of future tribomaterials can be conceived of in such a scenario: it seems likely that micro‐mechanical systems will achieve great importance, but silicon must be either surface protected or replaced by an optimised material; light metal alloys must be conditioned by surface treatment or coating; coatings must be improved, e.g., by nanomaterials; ceramic materials sintered at low temperatures from nano‐powders will be ductile and machinable, but retain the other beneficial properties of ceramics; and ultra‐precise surface finishing of materials may lead to nearly friction‐free and wearproof tribocontacts.
Macro‐ and microtribology — similar results, different origins?
Authors: Scherge M. , Schaefer J. A. 
Published: July 2006

AbstractMany friction effects are investigated extensively on both the macro‐ and the nanoscale. However, the range between these limits — the range of micrometres and micronewtons — has scarcely been probed. Using new test equipment, this particular range has been analysed. The example of the stick—slip phenomenon was chosen for discussion of the internal physical properties at different length scales. Results are presented for the entire range, from newtons to nanonewtons. Reality was simulated by friction testers operating at various length and force scales. The data were acquired with the help of a pin‐on‐disc tester for the macroscale, a novel micro‐friction tester for the microscale, and an atomic force microscope for the nanoscale.
The repeatability of friction and wear results obtained from unlubricated reciprocating sliding tests
Authors: Klaffke D. , Hartelt M. , Koesling F.‐P. 
Published: July 2006

AbstractLaboratory tests can help in the analysis of tribological failures of elements, and improve tribo‐systems by choosing appropriate materials. In order to characterise the friction and wear behaviour of candidate materials, various different test methods have been developed in the past and are still in use. One such method is the reciprocating sliding of a ball against a disc.In the work reported here, the repeatability of friction and wear results was evaluated with ten tests under identical conditions with a steel (100Cr6) or alumina (Al2O3) ball against a steel (100Cr6) disc under unlubricated conditions at room temperature. The influence of ambient humidity on friction and wear behaviour was determined in three additional tests in dry and in moist air, respectively. The repeatability of friction coefficient in normal air was better than 5% for alumina/100Cr6 and 12% for 100Cr6/100Cr6, while the repeatability of volumetric wear was slightly better than 10% for alumina/steel, and slightly worse than 10% for steel/steel.For both couples the coefficient of friction is lowest in moist air and about 50% higher in dry air. The coefficient of wear is also least in moist air and higher by a factor of 3(5) in dry air for tests with a 100Cr6 (alumina) ball.
An ESCA study of the effectiveness of antiwear and extreme‐pressure additives based on substituted phosphorodithioate derivatives, and a comparison with ZDDP
Authors: Jain M. C. , Unnikrishnan R. , Martin V. , Mehta A. K. , Bhatnagar A. K. 
Published: July 2006

AbstractAshless substituted dithiophosphoric acid derivatives (ADPs) are a new generation of multifunctional additives with promising antiwear (AW) and extreme‐pressure (EP) characteristics. Three such additives synthesised in the authors' laboratory have been evaluated for their AW and EP properties by standard four‐ball friction and wear tests. The friction‐reducing properties of these additives were compared with those of a commercial zinc dialkyldithiophosphate (ZDDP). It was found that the phosphorodithioate compounds studied here possessed excellent AW/EP properties. Their AW characteristics were found to be comparable to those of ZDDP at low loads. However, at higher loads they show inferior AW characteristics in comparison to ZDDP. Nevertheless, ADP derived from cashew nut shell oil had a higher load‐carrying capacity than ZDDP.The mechanism of the AW and EP behaviour exhibited by the different additives was investigated using X‐ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and scanning electron microscopy (SEM) of the worn surfaces formed during friction. XPS and AES analyses of the worn surfaces reveal that the tribochemical film formed on the ADP‐tested surfaces consisted mainly of metal phosphates and only a small amount of metal sulphides, even though the ADPs contained twice the number of sulphur atoms than phosphorus atoms. The ZDDP‐tested surface showed a mixture of metal sulphides and metal phosphates. Alkylamino substitution appeared to have no significant effect on the AW/EP properties of the additive.XPS and AES analyses also revealed that the tribochemical film formed on an ADP‐tested surface was thicker than that present on the ZDDP‐tested surface at low loads, whereas at higher loads the reverse was true. The higher weld load obtained for the blend containing cashew nut shell oil‐derived ADP is attributed to the thicker adsorbed reaction film formed on the surface due to the long alkyl groups present in the original additive structure. Short‐chain alkyl groups, however, form only a thin adsorbed layer, which may get rubbed off during the friction at high load. The low sulphide formation on ADP‐tested surfaces was attributed to the absence of any metal atom in the additive, which would help in the formation of metal sulphides during tribofragmentation and further tribochemical reactions.