摘要:

AbstractDuring a gear mesh cycle, load, rolling and sliding velocities, curvature, and temperature change rapidly. In this paper, a transient, thermo‐elastohydrodynamic lubrication model is presented that has been used to study the lubrication parameters at 250 contact points along the path of a contact. The working flanks were assumed to be smooth. The line load was calculated at every contact point, using the finite‐element method. Dynamic loading was not considered. The steady‐state temperature field of the working flanks was used to obtain the surface temperature at the inlet of each contact point, determined by an experimental‐analytical method presented previously. In this model, the lubricant is considered to follow the Ree‐Eyring constitutive equation. The influences of both pressure and temperature on density, thermal conductivity, and specific heat of the lubricant are also taken into account. Results are presented for an FZG type A gear pair lubricated with an FVA No. 4 reference oil; these include film shape, pressure and temperature distributions, as well as friction co

ISSN:0954-0075    

DOI:10.1002/ls.3010150402

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractTransient elastohydrodynamic (EHD) lubrication conditions occur in the contacts of many machine elements, such as gears, cams, and reciprocating devices, as a result of their working cycles. These conditions also occur in rolling‐element bearings at the onset or cessation of motion. The aspect of film thickness in elastohydrodynamically lubricated contacts subjected to a very rapid change in entrainment speed has not received much attention from researchers, probably because it is seen as less problematic than a sudden fall of the entrainment speed, which theoretically can lead to film failure. For a sudden stop, however, it has been shown previously that the lubricant forms an entrapment, which is able to protect the contact in many cases when the motion resumes. In this paper, EHD film behaviour under sudden acceleration is investigated; the study covers three cases ‐ starting from zero film, starting from an entrapped film, and starting from a continuous, steady f

ISSN:0954-0075    

DOI:10.1002/ls.3010150403

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractPhosphorodithioate derivatives having different alkyl substitu‐ents have been synthesised, while keeping the core phosphorus‐sulphur moiety intact. The change in antiwear, extreme‐pressure, and antioxidant properties with the variation in sub‐stituents at oxygen and at sulphur linkages in the phosphorodithioates has been studied. The role of the heteroatoms with regard to the alkyl substituents has been examined. The experimental data show that the chemical structure of an additive influences its physicochemical and tribological pro

ISSN:0954-0075    

DOI:10.1002/ls.3010150404

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractThis paper investigates the tribochemical reactions of n‐hexa‐decane proceeding in a tribosystem lubricated by n‐hexadecane at ambient and elevated temperatures. It is hypothesised that, at ambient temperature, reactions are mostly initiated by the mechanical action of the system, and at elevated temperature (200°C) thermochemical reactions should be dominant. An experimental study was performed using a ball‐on‐disc machine with steel‐on‐steel mating elements. To analyse wear tracks, Fourier transform infrared microspectrophotometry (FTIRM) and electron spectroscopy for chemical analysis (ESCA/XPS) were used. To investigate chemical changes in the bulk lubri cant, gas chromatography coupled with mass spectrometry (GC/ MS) was applied. The results provide clear evidence for the hypothesis that two types of oxygenation processes of n‐hexa ‐decane under boundary lubrication conditions should be considered. The first, at ambient temperature, is controlled by the mechanical action and the second is clearly controlled by temperature. The analytical techniques applied gave evidence of the formation of some reaction products from hexadecane under boundary lubrication conditions. These products include compounds having Fe‐O bonding (salts and chelates), carbonyl compoun

ISSN:0954-0075    

DOI:10.1002/ls.3010150405

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractCopolymeric succinamic acid (COSMA) additives have been synthesised in the laboratory and evaluated for their antiwear performance, both alone and in combination with zinc dialkyl‐dithiophosphate (ZDDP) in HVI light neutral oil. COSMA additives show antiwear behaviour and, in combination with ZDDP, exhibit a good synergistic effect, reducing the wear‐scar diameter by 60% and increasing the initial seizure load from 50 kg to 85–

ISSN:0954-0075    

DOI:10.1002/ls.3010150406

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

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

ISSN:0954-0075    

DOI:10.1002/ls.3010150407

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractAminodi(alkylphenyl) phosphorodithioates have been synthes‐ised by the condensation of di (alkylphenyl) phosphorodithioic acid, which was derived from a renewable, biodegradable, low‐cost, naturally occurring vegetable product, cashew nutshell liquid, with various amines. These ashless aminodi (alkyl‐phenyl) phosphorodithioates have been evaluated as anti‐oxidant, antiwear, friction‐modifying, and extreme‐pressure additives in lubricant c

ISSN:0954-0075    

DOI:10.1002/ls.3010150408

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

摘要:

AbstractAn N‐modified nano / micrometre borate (MNMB) as an oil additive was synthesised by an ultrasonic dispersion and emulsion reaction in the microemulsion phase. The particles of the MNMB additive were between 20 and 500 nm in diameter. The tribological properties of the MNMB as an oil additive were investigated using a four‐ball tester. The results reveal that the MNMB possesses good tribological properties. When the boron concentration is 0. 05 wt. %, the wear‐scar diameter is smallest and the seizure load is highest. The antiwear and extreme‐pressure properties of the MNMB were best at a viscosity of 65. 3 mms2. Small‐area X‐ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA) indicate that the MNMB additive can form a tribological mixed reaction film containing C, O, B, N, and Na on a rubbing surface. The elemental boron exists in four different chemical states, but is mainly present in the form of BN on the rubb

ISSN:0954-0075    

DOI:10.1002/ls.3010150409

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY

ISSN:0954-0075    

DOI:10.1002/ls.3010150401

出版商:John Wiley&Sons, Ltd    

年代:2003

数据来源: WILEY