bluuebunny/crossref_metadata_2025 huggingface dataset:
Conformational studies of 3‐hexyne
Authors: Churchill Geoffrey B. , Wiberg Kenneth B. , Bohn Robert K. , Michels H. Harvey
Published: July 2006

The microwave spectrum of 3‐hexyne has recently been observed and can be assigned unambiguously to a syn‐eclipsed C2v conformation. Owing to its nonpolar nature, a trans‐conformer (C2h) would not be observable in microwave studies. A gauche conformer (C2), which would exhibit tunneling splittings because there are two equivalent structures corresponding to a torsional angle of ±τ, was also not experimentally observed. In the present study, we determine whether computational studies can be carried out with sufficient accuracy to support these experimental observations. The torsional barrier to rotation in this molecule is expected to be of the order of 10–20 cal/mol, similar to that observed in 2‐butyne. This very low barrier offers a significant computational challenge. In an attempt to find a rigorous explanation for the observed stability of the C2v conformer, ab initio calculations were carried out at the Hartree–Fock (HF) and second‐order Møller–Plesset (MP2) levels of theory with several basis sets, ranging from 6‐311+G(d,p) to aug‐cc‐pVQZ. We find that the calculated potential energy surface for 3‐hexyne is extremely flat for variation of the torsional angle. The relative stability of the conformers of 3‐hexyne is quite dependent on the size of the basis set and tight convergence criteria must be used in the search for stable minima. Stable structures of nearly identical energy were found for the syn‐eclipsed C2v conformation and a gauche C2 structure. The trans‐C2h structure is found to be a transition state for the basis sets that were used in this study. The C2v structure has the lowest calculated energy using the aug‐cc‐pVQZ basis, in agreement with experiment. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Decoherence of a Greenberger–Horne–Zeilinger state in a five‐qubit NMR quantum computer
Authors: Kawamura Minaru , Morimoto Takuji , Mori Yoshiyuki , Sawae Ryuichi , Takarabe Kenichi , Manmoto Yoshinori
Published: July 2006

This work provides a simple approximate method of creating a Greenberger–Horne–Zeilinger (GHZ) state with high fidelity, using nuclear magnetic resonance (NMR) techniques, and reports on the decoherence process for these GHZ states, which is observed with a pair of encoder and decoder quantum circuits. The prepared GHZ states are verified by measuring the quantum correlations, which are well known as GHZ correlations. The results of the decoherence experiments, show that the GHZ states decay faster than bipartite entangled states such as Bell states by a factor of 1.3, and it appears that two different decoherence processes exist. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Detection of new fumonisin mycotoxins and fumonisin‐like compounds by reversed‐phase high‐performance liquid chromatography/electrospray ionization ion trap mass spectrometry
Authors: Bartók Tibor , Szécsi Árpád , Szekeres András , Mesterházy Ákos , Bartók Mihály
Published: July 2006

Fumonisins were produced in a rice culture infected with Fusarium verticillioides. To decrease the possibility of the formation of artifacts, the fumonisins were analyzed by reversed‐phase high‐performance liquid chromatography with electrospray ionization ion trap tandem mass spectrometry (RP‐HPLC/ESI‐IT‐MS2) immediately after the extraction of the culture material without any sample clean‐up. In addition to already known fumonisins, numerous new fumonisin mycotoxins and fumonisin‐like compounds were detected. On the basis of the IT‐MS2 data, detailed fragmentation pathways including new mechanisms were proposed for the different series of fumonisins. The retention times, the masses of the protonated molecules and of the product ions including the backbones and the characteristic neutral mass losses from the protonated molecules of the new compounds suggested their structures (applying the well‐known designation): iso‐FA1a,b, iso‐FB1a–d, iso‐FB2,3a–e, PHFB2a–c, PHFB4a–d, FB5/iso‐FB5a–d, FBK1 2TCA, FBK4 2TCA, FC2, iso‐FC2,3, PHFC4, FD and FBX series. The relative quantities of fumonisins and fumonisin‐like compounds found in the sample extract were expressed as percentages of FB1 (0.02–100%). The backbone of the compound denoted FD contained fewer carbon atoms than the well‐known fumonisins with the C19 or C20 backbone and may well be a precursor of the longer compounds. For the compounds denoted FBX (12 compounds), one or two OH groups attached to the fumonisin backbone were esterified by carboxylic acids other than tricarballylic acid, such as cis‐aconitic acid, oxalylsuccinic acid and oxalylfumaric acid. Copyright © 2006 John Wiley & Sons, Ltd.
Measuring contact pressure distributions under elastohydrodynamic point contacts
Authors: Johns‐Rahnejat P. M. , Gohar R.
Published: July 2006

Circular point contact EHD pressure distributions were investigated under various operating conditions using a thin film piezo‐resistive pressure transducer. A series of controlled experiments, in which the active element of the transducer is positioned at various contact cross‐sections, was carried out. The results are analysed and presented in the form of isobars. The pressure distribution closely describes the Hertzian pressure profile with a secondary pressure peak appearing prior to and near the exit constriction.
Studies on the shear stability of macromolecular additives by size exclusion chromatography
Authors: Florea M. , Luca Paula , Balliu S.
Published: July 2006

Factors affecting the mechanical stability of polyalkylmethacrylate type additives are comparatively examined for different shear degradation test methods and routine engine service, taking into account rheological and size exclusion chromatography data. The shear test methods are assessed regarding the MWD of the degraded additives.

The extent of degradation of macromolecular additives and the molecular weight distribution (MWD) of the degraded products depend on the nature and extent of shear stress, average molecular weight, MWD, chemical structure, nature of the base oil and temperature. The shape of the MWD of the sonicated and automotive service subject additives was found to be similar, unlike that of the additives sheared by the diesel injector method. These are narrower and more dependent on the initial MWD of the additive, especially in the case of the additives with broader MWD. A shear test that better correlates with service has to take into account not only the control of shear stress, by appropriate calibration, but also a suitable degradation mechanism.
On the influence of test parameters on friction and wear of ceramics in oscillating sliding contacts
Authors: Klaffke Dieter
Published: July 2006

The tribological behaviour of different ceramics in contact with steel was studied for the case of oscillating sliding motion with a ball‐on‐disc apparatus. The influence of several test condition parameters was investigated by a systematic variation of the stroke, frequency, and normal load at room temperature in laboratory air at different levels of relative humidity. Each of the four parameters was varied in three stages. While the coefficient of friction was only mildly influenced by the operational variables, the coefficient of wear showed great variations and depended strongly on the humidity of the surrounding air. The effect of the operational variables and of the humidity on friction and wear varied for the different materials under investigation.
An accelerated simulation test apparatus for evaluating elevated temperature erosion‐corrosion behaviour of iron and steel in gas‐solid flows
Authors: Shaoguang Liu , Ping Wang , Daoyuan Wang , Jiubang Chen , Qingmei Zen , Xingcheng Guo , Delin Shu
Published: July 2006

This paper introduces an accelerated simulating test apparatus for evaluating high temperature erosion‐corrosion behaviour of iron and steel in gas‐solid flows. This device is designed to investigate the high‐temperature erosion‐corrosion properties of materials and to optimise anti‐erosion‐corrosion measures for iron and steel parts. It simulates the working conditions of the pipes in an economiser. We have shortened the test duration by increasing the density of abrasive particles in the fluids. The test set up is composed of six main parts, including the blowing system, heating system, feeder/mixer, erosion‐corrosion chamber, and loading system, the cooling system, and the control system. Four years' operation has shown that the repeatability for the experimental results is good. The SEMs of the worn surfaces of both specimens and actual pipes in the economiser show that they are consistent with each other. Four years' operation has shown that the test apparatus is characterised by reliability and good simulation ability. Both practical and theoretical research work can be done with this device.
High‐temperature erosion tests on materials for fluidized bed combustor heat‐exchanger tubes
Authors: Martinella R. , Menetti L. , Angelo D. D'
Published: July 2006

In order to simulate and predict the erosion damage suffered by in‐bed tubes in fluidised bed combustors, dedicated test equipment was set up at CISE's tribology laboratory with ENEL S. p. A (Italian National Electricity Board) support. This erosion rig was used to test and characterise the behaviour of AISI 310, P9, and P22 steels, candidate materials for this type of heat‐exchanger tube. Tests were carried out at room temperature to characterise the erosion behaviour of these materials and at higher specimen (350°C and 500°C) and air (840°C) temperatures to simulate and characterise their behaviour in service. From this experimental work it turned out that, while at room temperature, the erosion behaviour of the three materials did not differ significantly, at high temperature P9 showed the best resistance in both test conditions and AISI 310 displayed an optimum behaviour at normal impact angles, but had the higher erosion rate at 30° impact angle.
An engineering theory and an experimental method for contaminant wear testing
Authors: Ruiqing Jia , Zhixin Xia , Hesheng Shao , Mingyun Zhang , Liangju Wang
Published: July 2006

An engineering theory and experimental method for contaminant wear are proposed. By analysing the wear characteristics of hydraulic components, the contaminants' wear strength σm, wear factor ƒm, lubrication parameter λl, flexibility parameter λa, and material parameter λm, etc., can be defined. In addition, a new test apparatus, ‘MMU‐5’, that can be used for studying wear properties under lubrication conditions, is reported. The friction pair of the tester is composed of two ring specimens. The most important aspect of this tester is that the gap between the two specimens can be adjusted from 0 to 100 microns. Using the tester, parameters such as λl, λa, λm, and ƒm, are investigated experimentally. Finally, the application of the corresponding engineering theory is assessed.
Method of abrasive wear testing in comminution processes
Authors: Scieszka Stanislaw F.
Published: July 2006

The abrasive wear properties of materials in sliding contact with solid mineral particles during a comminution process have been studied. The equipment used can simulate tribo‐conditions inside coal pulverisers. Using the experimental apparatus, a number of different materials have been tested and classified according to their resistance to abrasive wear in rubbing contact with particulate coal. The method and principles of three new rigs have been described in the previous paper (see p. 235).
Laboratory shearing tests for viscosity index improvers
Authors: Mortier Mieke
Published: July 2006

The relative resistance of VI improvers to breakdown depends on internal structural parameters (chemical type, ratio of monomers, degree of branching) as well as on external factors (test type, duration, severity).

Of the many bench tests available to screen shear stability, the 30 cycle CEC injector test is most commonly used for engine oils. Test duration, however, can significantly change the relative ranking of VI improver shear stability. While some polymers stabilise quickly, others continue to degrade when test duration is extended. Some polymers are also more susceptible to the severity of the shearing conditions encountered, e.g. in the FZG and the Tapered Bearing tests.

It is therefore important to determine which test, and which set of conditions, will rank shear stability of different VI improver types in the same order as does the field.
Lubricant related factors controlling oil consumption in diesel engines
Authors: Van Dam W. , Kleiser W. M.
Published: July 2006

Oil consumption control in internal combustion engines is affected by both engine design and lubricant related factors. In an attempt to study the lubricant related factors, an oil consumption measurement engine test, using the Mercedes‐Benz OM 364A engine, was developed. The engine test data confirm the effects of viscosity and volatility. In addition, the results indicate that the selection of base oil and viscosity index modifier may have an effect on oil consumption which would not be predicted from the rheological properties of the oil.

From various different engine tests, indications were obtained about a possible relationship between oil consumption and viscosity increase. A data search yielded results that confirm this correlation.
The importance of static friction characteristics of brake friction couple, and methods of testing
Authors: Ścieszka S. F. , Jankowski A.
Published: July 2006

Detailed knowledge about static friction materials is required for the accurate calculation of the braking torque needed to hold a load at rest. This is particularly important for brakes in cranes, elevators, hoists and mining winding machines, which must meet specifications such as the definite value of the static safe braking factor. The study of static friction is also a useful supplement to the dynamic testing of brake friction materials. In such a study, precise control of the temperature on the surfaces is possible, as well as surface roughness, and existence of the third‐body can be accurately identified. It is an important fact that the coefficient of static friction, μs, is not an invariant, and it cannot be adequately represented in many engineering applications as a single number. The study of static friction dependence upon factors such as stationary contact time, rate of tangential loading, and surface temperature, contributes to a better understanding of friction phenomena.

In this paper, a test apparatus is presented, and a series of experiments is described. The experiments reveal the static friction characteristics of some brake friction materials.
The effect of slip amplitude and test time on fretting wear in metal‐metal contact
Authors: Vižintin J. , Kalin M. , Podgornik B. , Vodopivec F.
Published: July 2006

A study was conducted to determine the effect of amplitude and test time on surface damage in metal‐to‐metal contact under lubricated conditions. The test set up consisted of a ball loaded against a flat disc, with an external drive imparting a linear oscillatory motion to the ball on the flat. The materials were steel AISI 52100/AISI 52100, and the lubricant was ISO VG 220. Damage characteristics were defined for amplitudes in the range of 5 to 50 microns and for test times of 10 to 360 min.
An approach to tribosystem simulation and tribotesting
Authors: Kuzmin N. N. , Shuvalova E. A. , Checkina O. G.
Published: July 2006

This paper proposes an approach to the problems of simulation and description of tribosystems, based on an investigation of various fundamental aspects of tribosystem operation. A complex of parameters to be measured in testing, and characteristics analysed after the tests, are selected, using the authors' experience in tribotesting. Methods of processing experimental data and their interpretation are discussed. The approach described here has been successfully used for solution of various practical problems.
Predictability of high‐performance spindles using a complete thermo‐elastohydrodynamic lubrication (TEHD) solution
Authors: Pahud Pierre , Rüstenberg Ines
Published: July 2006

Spindles experience problems related to increased power and velocity, and can have very high power consumption. The work reported here is aimed at improving design methods for high‐performance spindles and machine‐tool bearings, and is aimed at determining the influence, of the oil quantity supplying the contact, on power consumption and on contact temperature. A finite element program, TACT, can efficiently predict power loss and the thermal state of machine‐tool bearings, and the remaining unknown in these thermo‐piezo‐viscous‐elastic (TPVE) calculations is inlet oil film height. The authors address this problem and, within the context of this work, develop a high‐speed ISO 50 spindle which has a thin‐wall bearing housing, and is ‚thermally tuned‚, so avoiding thermal instability, while the preload stays constant. Its experimentally determined power consumption values agree well with the TPVE prediction for an assumed inlet film height of 0.5 μm.
A new approach to wear testing of case‐hardened steels
Authors: Senatorski Jan , Tacikowski Jan
Published: July 2006

This paper reports a three‐cylinder‐cone test configuration, which is claimed to be more appropriate to testing the tribological properties of surface hardened steels. Tests are run, for comparative purposes, against a Falex (pin and vee‐block) and Amsler (disc on disc) machines, and the results compared. For various plain carbon, low and medium‐alloy structural steels, nitrided and heat treated under various conditions, and for various test conditions, results are given for the three test methods and apparatus. An example is also given of laboratory simulation of a rubbing part in a hydraulic motor. © Leaf Coppin 1997.
Advanced lubricants for diesel engine particulate control
Authors: Gates Richard S. , Hsu Stephen M.
Published: July 2006

Diesel exhaust particulates contain an organic fraction than can be attributed to the engine lubricant. This lubricant fraction varies from a mass fraction of 15% to over 50%, depending on the engine and the operating conditions. This paper addresses the issue of developing novel lubricants that have a lower contribution to diesel particulate. In this work, an analytical technique (TGA/DTA) was developed to measure rapidly the lubricant contribution to diesel particulate. Two apparatus were constructed to simulate the interactions between carbonaceous soot and lubricant products under a variety of test conditions. The combination of simulation apparatus and analytical technique guided the development of lubricants with reduced contribution to particulate. Several formulated lubricants were developed, based on concepts of lower volatility and better oxidative and thermal stability. Initial testing of these lubricants in the simulation apparatus indicated several candidates with reduced interaction with diesel particulate soot.
Diesel lubricant monitoring with new‐concept shipboard test equipment
Authors: Gorin N. , Shay G.
Published: July 2006

Accurate diesel lubricating oil testing, formerly relegated only to oil laboratories, can now be performed routinely aboard ship using a series of first‐generation, new‐concept, oil analysis meters. The modern design equipment yields reliable oil test data whose quality approaches that derived from traditional, but often difficult to perform, oil laboratory testing. This equipment contains operating concepts that were jointly codeveloped for fleet use by contractors with direct technical input from NSWCCD‐SSES engineering personnel. The oil testers available are compact, affordable, streamlined, microprocessor‐based devices, containing simplified hardware and menu‐driven software. Further, these devices were designed with extensive onboard oil‐test data storage capabilities. Engine test data obtained is stored so that it can be offloaded to a printer or a computer for operational trending, characteristics that are useful for long‐term tracking of engine conditions, commensurate with condition‐based machinery maintenance concepts. Design ideas employed in the equipment were aimed at making it essentially equivalent to laboratory testing, yet operator‐friendly and easy to use.

Evaluation of the testers was completed in about three years from initial conception until commercial products were realised. Included in the evaluaton studies were statistical data comparisons with established testing procedures, along with long‐term fleet testing. The equipment includes kinematic viscosity, fuel dilution (FD), and total base number (TBN) meters.

Additional work is continuing on the development of similar equipment for assessing moisture, solids contamination, wear/particle analysis, and total acid number (TAN) evaluations in other oils, so that the US fleet may increase real‐time analysis and diagnostics capabilities.
On the influence of surface finish of SSiC on the results of tribological laboratory tests in the case of water lubricated oscillating sliding
Authors: Klaffke D. , Hartelt M. , Spur G. , Weigmann U.‐P.
Published: July 2006

The development of materials for tribological applications requires characterisation of their friction and wear behaviour. This characterisation is often based on tribological model testing, working with simple shaped specimens, running under well‐defined conditions. Discrepancies in test results may arise from the fact that non‐standard tests with different sets of operational parameters are used.

An essential starting point for the development of tribological standards is knowledge of the main parameters that influence the tribological properties. One aspect that is not often adequately taken into account is the surface finish of the test specimens. Results are presented of friction and wear tests with self‐mated SSiC couples (ball on disc), running in water in an oscillating sliding mode. The surfaces of the disc were ground, lapped, or polished, respectively, running against a polished ball.

For certain test conditions, the influence of the surface finish on wear is found to be negligible, while for other conditions, the wear rate can differ by one order of magnitude or even more.

The consequences for the standardisation of wear tests of ceramic materials are discussed.
Rerefining of used oils — a review of commercial processes
Authors: Dang G. S.
Published: July 2006

The total demand for lubricants in India is in the region of 855,000 tonnes a year. This constitutes 1.5% of total petroleum products consumption. Presently, there are three lubricant refineries in the country with a total installed capacity of 535,000 tonnes. The shortfall, of about 370,000 tonnes (approximately 45% of demand), is met through imports. In addition, there are generated 60,000–65,000 tonnes a year of base oil through rerefining of used oils. The three refineries are being expanded in order to raise base oil production to 810,000 tonnes per annum. Some other refinery projects are also under consideration and approval by the government. The current expansion programmes, together with the projected new refineries, are expected to make India self‐sufficient in terms of base stock production lubricant.

Overall, lubricant production in India is entirely dependent on imported lubricant‐bearing crudes, and not on the indigenous crudes, which are non‐lube bearing. With recent advances in engine design, together with improved lubricant quality through high‐performance lubricants, the consumption, or demand rate, has been in decline or unchanging in most countries. In India, a gap still exists between production and demand of lubricants, necessitating import. Since they are a high‐value, non‐energy product, lubricant conservation measures are therefore essential.

Interest in rerefining of used oil is increasing, with more and more emphasis on making the processes environmentally friendly. The conventional acid‐clay rerefining process is environmentally unfriendly, and hence needs modification. An attempt is made in this paper to highlight various rerefining processes available. The relative merits and demerits of each process are discussed, and among the various processes, that based on molecular/high vacuum distillation is covered in detail.
Anti‐shudder durability of automatic transmission fluids: Mechanism of the loss of shudder control
Authors: Watts R. F. , Nibert R. K. , Tandon M.
Published: July 2006

Field samples of automatic transmission fluid (ATF) from vehicles fitted with controlled‐slip torque converter clutches have been analysed to determine the cause of the onset of vehicle shudder. A laboratory anti‐shudder test has been developed using the SAE No. 2 machine. This test includes several degradation mechanisms: thermal degradation in engaging clutches, oxidative degradation in the presence of catalytic metals, and degradation produced by a continuously sliding clutch. At least in the case of one specific fluid, the mode of failure produced in the laboratory test was very similar to the mode of failure in the vehicle. Fluids with improved anti‐shudder durability have been evaluated by this test method and fail by different mechanisms. Test matrices have been conducted to separate the contribution of fluid and hardware to the loss of shudder control in these systems.
Efficiency determination of cylindrical gear units in a back‐to‐back gear test rig
Authors: Miloiu G.
Published: July 2006

A method is presented for determining the efficiency of gear units in test rigs with a mechanically closed energy flow, based on measuring the losses in the rig, that is, the torsion torque at the driving motor and the stabilised thermic level. The energy losses between the two gear units would be separated according to the direction of power flow within the stressed framework of the rig.

Experimental results are given for gear units including three types of gears, i.e.: involute gears with hobbed toothing, involute gears with ground toothing, and Wildhaber/Novikov (W/N) non‐involute circular arc gears with two meshing lines, achieved by hobbing.
A new methodology to estimate starvation in ball bearings
Authors: Olaru D. N. , Gafitanu M. D.
Published: July 2006

In agreement with isothermal EHD theory, increases in speed and lubricant viscosity determine the increase in film thickness. Beyond certain limits, both speed and viscosity lead to a decrease in film thickness, as a result of thermal effects and starvation. To estimate starvation limits and film thickness in high‐speed, mist‐lubricated ball bearings, a new analytical methodology has been developed. This methodology is based both on the oil flow rate in ball‐race contacts and Hamrock and Dowson's starvation theory. This new methodology has been used to estimate minimum film thickness in a 7206C angular contact ball bearing, axially‐loaded, and rotated between 0 and 35,000 r/min−1. Good correlation between computed and experimental values of the minimum film thickness have been obtained.
A comparative study of different wear measurement techniques applied to fretting wear of a spherical against a flat steel specimen
Authors: de Baets P. , Strijckmans K. , van Peteghem A. P.
Published: July 2006

One of the main problems in fretting wear research is accurate measurement of the very small wear volumes (in microgams) produced. Different techniques, with their own advantages and disadvantages, can be used. Classic wear techniques lack sensitivity and often fail to measure the fretting wear volumes at all, or are not accurate enough. The authors have developed a Thin Layer Activation (TLA) method for quantification of the fretting wear of steel surfaces. The same method can also be used to determine material transfer between wear specimens. In this paper, the different methods are reviewed, and their accuracy in terms of the fretting wear measurement of steel surfaces is discussed. It is concluded that TLA has relatively good reproducibility and accuracy in comparison with classic fretting wear measurement techniques, such as normal approach measurement and spherical cap modelling. Modern threedimensional profilometry has better reproducibility than TLA, but is afflicted by systematic errors because of the oxidation of the metal surface. The different methods emphasise different features of the fretting process, and it is advisable to use them together for measuring fretting wear; their combined use provides a better understanding of the fundamentals of the fretting wear process.
A disc‐on‐flat wear test under starved lubrication
Authors: Levitin M. , Shamshidov B.
Published: July 2006

The ‘disc‐on‐flat’ system has been used for testing wear under starved lubrication conditions. The rotating discs were made of a carbon steel, the surface finish of the discs being ground. Some of the discs were treated by ‘vibrogrooving’, to form regular microrelief. The flat counterface was made of a ground copper alloy. An industrial oil was used as a lubricant in a one‐drop test procedure. Microreliefs of a non‐touching design with a relative groove area of 34% caused less wear than microreliefs of a touching type with a relative groove area of 50%, whereas the wear caused by the ground disc was high, with seizure after 200–250 m of sliding distance. A one‐drop disc‐on‐cylinder test also showed that the wear caused by discs with regular microrelief was considerably less than that caused by discs treated by conventional finishing (grinding, polishing).
Three‐dimensional description of sheet‐metal surfaces
Authors: Wagner Stefan
Published: July 2006

During sheet‐metal forming processes, the friction conditions have a decisive influence on forming limits, the robustness of the production process, and the quality of the parts produced, with significant forces required to overcome friction between the sheet and the tools. If batch‐to‐batch reproducibility is to be guaranteed, an appropriate method of characterising the sheet surface topography is needed to monitor the sheetmetal fabrication process. Newly developed optical measurement techniques and computer workstation technology are presented, which enable the topography of sheet surfaces to be described in three dimensions. New parameters for describing sheet surface topography are developed. This may correlate more closely with frictional behaviour in sheet stamping than the previously used two‐dimensional parameters, with the size, shape, and distribution of the peaks and valleys of the topography defined. Results generated on a special drawing friction test machine indicate that numerous narrow peaks and large, separate, uniformly distributed valleys yield a desirable resistance to adhesion.
Severity of wear: A new index
Authors: Jones M. H. , Alberich J.
Published: July 2006

A Time Dependent Particle Quantifier (TDPQ) system can measure the concentration of ferrous wear debris suspended in a lubricant, and the severity of wear associated with the particle size of this suspended debris. A coding system is proposed covering: PQ index (total wear); initial TDPQ slope (large particles); and final TDPQ slope (small particles). Correlation with existing measurement systems is also given.
Functional behaviour of PVD coatings under sliding and rolling stress conditions
Authors: zu Köcker G. Meier , Santner E. , Löffelbein B.
Published: July 2006

Whereas wear‐resistant PVD coatings are well established in the field of metalcutting, and the functional and tribological behaviour of these coatings is well known under such conditions, PVD coatings are used only occasionally in mechanical engineering. The reason for this seems to be the lack of information concerning the functional behaviour of these coatings in closed tribosystems.

To evaluate new areas of application together with optimised coating compounds, model wear tests were performed under sliding, rolling and slip‐rolling stress conditions. In addition, the test parameters, such as sliding speed, load, ambient temperature, and number of revolutions were varied, as were the coating compounds and their thicknesses.

The results obtained show that friction and wear of PVD coatings are both strongly influenced by the kind of stress and the test parameters themselves. Coatings that perform well under certain test conditions can break down quickly under some other stress conditions. TiN coatings, for example, which display low friction and wear under sliding friction, fail under rolling conditions very shortly afterwards.
Evaluation of various methods to detect metallic wear particles in lube‐oil filter debris
Authors: Fisher Gary C.
Published: July 2006

Studies were conducted to evaluate methods of detecting metallic wear particles in lube‐oil filter debris. The methods studied were: low‐temperature oxidation of the organic constituents in the debris, separation of ferromagnetic particles by passage through a magnetic field, and counting/sizing of metallic particles in a fluid stream using a commercially available detector. Laboratory‐prepared simulations of wear debris and actual filter debris samples from operational military aircraft systems were used in the evaluation. The relative ability of each method to detect metallic wear particles is discussed, along with the effects of each method on subsequent debris examination.
Development of a combined AFM‐tribometer test rig
Authors: Sch Jörg , Schneider Thomas , Santner Erich
Published: July 2006

A test rig has been developed that combines an atomic force microscope with a tribometer built for testing sliding electrical contacts. This instrument is able to visualise the onset and development of topographical changes in surfaces due to tribological stress, quasi in situ, at ambient air conditions. The spatial resolution reaches atomic levels, and exact quantitative topographical information is available in all three dimensions. Using a so‐called ‘stand‐alone AFM’, commercial components can be tested without the need for extended sample preparation.

Some first measurements on the conductive plastic film of a commercial potentiometer tribologically stressed by a precious metal wiper are presented. The results demonstrate that all surface modifications in a selected area occurring within the first few stress cycles can be visualised and prepared for quantitative analysis. Topographical changes can be identified as a combination of adhesive and abrasive wear leading to the formation of small plateaux that are partly built up from wiper material, and have widths in the region of 5 μm to 10 μm.
Tribology and tribodiagnostics in Russia: An overview
Authors: Bronovets M. A. , Zaritsky S. P. , Lopatin A. S.
Published: July 2006

This paper offers a brief look at the development of the theory and practice of tribology and tribodiagnostics in Russia. It covers the main directions in tribology, and looks at magnetofluid (ferrofluid) tribosystems, classification of triboelements, tribomonitoring systems, thin‐layer activation, renovation of tribosystems without disassembly, tribosystems with automatic wear compensation, and controlled tribochemical regimes.
Development of an experimental rig with hydrostatic bearings for testing the EHD traction force of high‐speed lubricants
Authors: Yang  , Bo‐Yuan  , Zheng  , Pei‐Bin  , Yang  , Ru‐Ping  , Shen  , Ming‐Wu  , Wang  , Teng‐Fang
Published: July 2006

A test rig for the EHD traction force of lubricants is essential equipment for the study of the non‐Newtonian properties of lubricants operating at high pressure. In this paper is described the development of test equipment with hydrostatic bearings, on the basis of analysis of EHD traction and other test rigs. Hydrostatic bearings allow the rig to pick up the signals of the EHD traction force more precisely. Thus, good test results for an aviation lubricant have been obtained.
Filtration characteristics of magnetic fibrous polymer as a new oil filter material for lubrication systems
Authors: Ahn Byeng‐Gil , Choi Ung‐Su , Shim Hyun‐Hae , Kwon Oh‐Kwan , Moon Tak‐Jin
Published: July 2006

Magnetic fibrous polymeric filter (MFPF) elements for lubrication systems were obtained by pneumoextrusion of a thermoplastic polymer (polyamide) containing a magnetic particulate filler (barium ferrite), and treating it subsequently in magnetic fields. Using a standard laboratory oil filtration test rig, metallic particle quantifier, and an image analyser system, the dependence of the filtration characteristics of the magnetic filter medium on the magnetic parameters was investigated. The variation of pressure drop and filtration efficiency with the packing density of the lubricating filter elements was measured. A conventional lubricant filter for an internal combustion engine was also tested for comparison with the filtration performance of the magnetised filter medium. Increasing the magnetic force of the filter medium made the MFPF material more effective in filtering fine ferrous particles, without changing the pressure drop. It was concluded that MFPF can be used as an effective filter in lubrication systems.
A method of measuring ‘zero‐wear’ of the cylinder liner
Authors: Pawlus Pawel
Published: July 2006

In this paper, new methods of linear wear estimation of the cylinder liner are proposed. They can be used if the deepest honed valleys remain unaltered during the wear process. In the first part of the paper, the possibility of using various amplitude parameters as measures of wear is studied. The second part presents a new procedure for cylinder liner wear analysis based on the ‘fax‐film’ method that allows us to estimate the wear of the cylinder liner without disassembly of the cylinder‐piston‐piston ring group.
Open‐gear lubrication: Meeting industrial requirements using laboratory techniques
Authors: de Vaal Philip L.
Published: July 2006

This paper gives a general overview of open‐gear lubricants. In order to evaluate contending lubricants, laboratory tests are often used as a preliminary screening. When care is taken to perform laboratory tests under conditions which represent the actual operating conditions, simple laboratory tests can be conducted to evaluate products before a product is selected for use in trial runs on actual equipment. In planning laboratory tests, the industrial requirements need to be clearly defined, from the perspective of the supplier, as well as that of the user. Factors such as environmental acceptance, toxicity, and ease of disposal of spent lubricant play as important a role in the formulation of new products as do requirements related to performance, like pumpability, sprayability, adhesiveness, load‐carrying ability, and wear protection capability.
Wear simulation of spur gears
Authors: Flodin Anders , Andersson Sören
Published: July 2006

This paper deals with prediction of wear in spur gears, which has been calculated using an approach in which the wear depth on a tooth surface is integrated over time using the Euler integration method. Variations in pressure distribution over the surface have been considered, as well as changes in curvature and surface profile of the teeth as they wear. The paper focuses on the use of an appropriate wear model for simulating wear using calculated conditions between high‐performance slow‐running lubricated spur gears. A numerical model for prediction of surface interaction of spur gears developed earlier by the authors has been applied as the basis for the simulation of wear using different wear models. Owing to the nature of the wear models, methods of calculating the contact temperature have been investigated for the specific case of interacting gear teeth. It was found that a linear wear model, when compared with a more complex oxidation model and with a model based on adsorption of lubricant molecules, satisfactorily predicts wear. It was also found that it is the geometry of the gears that causes sliding velocity to be the dominant wear‐inducing factor, and so determines the general nature of the wear behaviour.
An improved crater grinding micro‐abrasion test
Authors: Engqvist H. , Axén N. , Hogmark S.
Published: July 2006

The crater grinding test was originally developed for micro‐abrasion evaluation of thin hard coatings. It is capable of determining the wear constants of the coating and substrate individually, even for very thin coatings. Crater grinding micro‐abrasion tests also make very small wear scars and are thus virtually non‐destructive.

This paper evaluates modifications of the crater grinding test configuration in order to increase its accuracy and repeatability. In particular, new geometries of the wearing wheel have been tested on bulk samples of cemented carbides and alumina, and the effects of misalignments in the test equipment are also investigated. The proposed improvements to the test are shown to generate results with better accuracy and repeatability.
Oxidation stability of gasoline engine lubricants: Effect of base‐oil chemistry in laboratory and engine tests
Authors: Faure D. , Hipeaux J. C. , Guevellou Y. , Legros A.
Published: July 2006

This paper presents a laboratory test called the Iron Catalysed Oxidation Test (ICOT), where air is bubbled through an oil sample at 165 °C. This test, shorter than the CEC L‐48 test, provides an easy method of gasoline engine lubricant screening. A basic study has shown that this kind of test is suitable for the discrimination of base‐oil properties and that the oil viscosity increase at the end of the test is highly indicative of the oxidation processes at work. In this study, the base‐oil assessment is carried out with an API SG SAE 15W‐40 oil, and the results depend directly on the aromaticity of the base oil. Several engine test sequences, including CEC L‐55‐T‐95: TU3M HT, were also applied to these formulations, which differ only in their base oils. The results of those sequences where oil consumption was low roughly correlated with the laboratory test results. However, when there was a high loss of volatile matter in the engine tests, the oil viscosity increase was greatly modified, and this parameter can override the effect of oxidation.
Pitting load capacity test on the FZG gear test rig with load‐spectra and one‐stage investigations
Authors: Höhn B.‐R. , Oster P. , Schedl U.
Published: July 2006

Lubricants in their combination of base oil and additive influence the pitting and micropitting load‐carrying capacity of cylindrical gears. The aim of the FVA ‘Pitting test’ research project was to develop and establish a test method on the standard FZG gear test rig with a centre distance a = 91.5 mm. Two different test procedures were proposed, one using a load spectrum and the other a constant load. These tests can be used to determine the relative pitting load capacities of reference and candidate oils. From these results the pitting load‐carrying capacity can be calculated.
On the influence of some test parameters on the results of oscillating sliding tests
Authors: Klaffke D.
Published: July 2006

The friction and wear behaviour of materials is often characterised in laboratory tests using a simple ball‐on‐flat configuration. From this type of test can be derived information useful in guiding the development of tribomaterials and in helping select candidate materials for specific applications. A large variety of tribotesting methods exists, and indeed several are not yet standardised. One of these methods is the oscillating sliding test, where a ball moves in relation to a disc, usually with small strokes. This method is almost non‐destructive and can be applied to very small specimens. One of the most important parameters in laboratory tests is the humidity of the surrounding air. Experimental results on the friction and wear characteristics of different ceramics tested against different ball materials at room temperature in oscillating sliding contact are presented here and discussed, taking into account the effects of the test duration, relative humidity, and counterbody material.
Mechanical testing of hydraulic fluids
Authors: Reichel Jürgen
Published: July 2006

The antiwear properties of hydraulic fluids are important because hydraulic pump and motor wear is costly. While international hydraulic fluid performance standards continue to be developed, e. g., the ISO/TC28/SC4 committee's draft ISO DIS 11158 ‘Specifications for mineral oil hydraulic fluids’, the normal hydraulic fluid performance specifications represent minimum requirements. Performance specifications for nonmineral oil hydraulic fluids are also being developed.

Typically, both the user and the fluid manufacturer possess insufficient objective information about the antiwear properties of special fluids, e. g., environmentally acceptable hydraulic fluids (EAHF) or fire‐resistant hydraulic fluids (FRHF) for use in hydraulic equipment such as axial‐piston pumps, vane pumps or radial‐piston motors. Manufacturer's specifications must therefore be determined. The required lubrication properties can be determined by either laboratory pump tests or a field trial, often at the customer's expense. The lubrication properties of a hydraulic fluid should ideally be determined under conditions that are equivalent to field practice.

This paper will discuss the use of the vane pump test and the FZG gear test to gauge ‘recommended’ hydraulic fluid performance; many non‐mineral hydraulic fluids, such as environmentally acceptable hydraulic fluids, fire‐resistant fluids or synthetic hydraulic fluids, cannot be used in axial‐piston systems based only on results obtained with these tests, and additional testing is always required. Proposals are made for testing of such fluids on a variable‐load test rig. These tests are done with axial‐piston pumps, or other similar displacement systems, and are intended to determine the industrial suitability of non‐mineral hydraulic fluids.
Tribological properties of plasma nitrided AISI 4140 steel under dry and lubricated sliding conditions
Authors: Podgornik B. , Vižintin J.
Published: July 2006

In this investigation, the microstructural, mechanical and tribological properties of plasma and pulse plasma nitrided AISI 4140 steel have been investigated in comparison to hardened steel. The influence of nitriding case depth, as well as the presence of a compound layer, have been tribologically examined for both dry and lubricated sliding. Testing was carried out on a pin‐on‐disc machine in which surface‐treated pins were mated to hardened ball bearing steel discs. The surface treated samples were characterised using metallographic, SEM, microhardness and profilometric techniques, before and after wear testing. The resulting wear loss and coefficient of friction were monitored as a function of load and of test time. The results showed improved tribological properties of the AISI 4140 steel after plasma and pulse plasma nitriding as compared to the hardened steel, in both dry and lubricated sliding. However, the compound layer should be removed from the surface, either by mechanical means or by decreasing the amount of nitrogen in the nitriding atmosphere, in order to avoid impairment of the tribological properties by fracture of the hard and brittle compound layer, followed by formation of hard abrasive particles.
Fundamentals of tribotesting
Authors: Klaffke Dieter
Published: July 2006

Tribology is an experiment‐oriented branch of a complex, interdisciplinary science, in which testing plays a major role in the solution of technical problems, in the field as well as in the development of tribomaterials. Various test methods are used for this purpose, and the results are sensitive to the choice of test method and test conditions.

In this paper, the effects of test parameters on friction and wear results are considered, some selected results of model tests with different types of materials are presented, and guidelines are derived, that help improve the reliability and level of confidence of tribological tests performed in laboratories.