Influence of the alkyl group of zinc dialkyldithiophosphate on the frictional characteristics of molybdenum dialkyldithiocarbamate under sliding conditions

Muraki, Masayoshi; Wada, Hisayuki

doi:10.1016/s0301-679x(02)00092-0

Cited by 40 publications

(25 citation statements)

References 10 publications

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“…Formation of MoDTC tribofilms is affected by parameters such as temperature, MoDTC concentration, the presence of antioxidants and other lubricant additives as well as contact parameters such as the stroke length, sliding speed, slide-roll ratio and surface roughness of the sliding pair which in turn affect the friction performance of the additive [6][7][8][9][10][11][12]. Although there is a consensus within the research community that MoDTC reduces friction by formation of MoS 2 within the contact region, there is still no mechanistic model that links additive chemistry in a dynamic tribological system to friction and wear performance.…”

Section: Introductionmentioning

confidence: 99%

A methodology for Raman characterisation of MoDTC tribofilms and its application in investigating the influence of surface chemistry on friction performance of MoDTC lubricants

2015

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In this study, Raman spectroscopy has been employed to understand the influence of surface chemistry on friction in a tribocontact. Tribotests were conducted using molybdenum dialkyldithiocarbamate (MoDTC) lubricant in a steel/steel sliding contact. Firstly, surface chemistry in the high friction regime, at the beginning of the test, and in the low friction regime, after longer test duration is investigated. Secondly, the influence of temperature on the surface chemistry of the resulting wear scars is investigated. Results show that at the beginning of tribotests with MoDTC lubricant, iron oxides are formed in the tribocontact which result in high friction. At longer test durations, adsorbed MoDTC on the ferrous surface decomposes to form MoS 2 and low friction is observed. Surface chemistry at the tribocontact has been found to vary depending on the test temperature. At high temperatures, MoS 2 is formed which provides friction reduction while at low temperatures, molybdenum oxide and amorphous sulphur-rich molybdenum (MoS x ) compounds are formed which do not provide friction reduction. Furthermore, it has been shown that MoS 2 formed within the tribocontact at high temperatures has a slightly disordered crystal structure as a result of tribological processes.

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Section: Introductionmentioning

confidence: 99%

A methodology for Raman characterisation of MoDTC tribofilms and its application in investigating the influence of surface chemistry on friction performance of MoDTC lubricants

2015

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“…A lot of investigations have been conducted to evaluate the performances of additive mixtures and to determine the composition of associated tribofilms. Several factors were identified as playing a role: additive structure [1,2], additives concentration [3][4][5][6], base oil nature [7,8], …, or combinations of these parameters. A detailed review on published information on that topic was written by Willermet [9].…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of MoDTC and ZDTP on Frictional Behaviour of Tribofilms at the Nanometer Scale

et al. 2004

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The layered structure and the rheological properties of anti-wear films generated in a rolling/sliding contact from lubricants containing zinc dialkyldithiophosphate (ZDTP) and/or molybdenum dialkyldithiocarbamate (MoDTC) additives have been studied by dynamic nanoindentation experiments coupled with a simple modelling of the stiffness measurements. Local nano-friction experiments were conducted with the same device in order to determine the evolution of the friction coefficient as a function of the applied pressure for the different lubricant formulations. For the MoDTC film, the applied pressure in the friction test remains low (<0.5 GPa) and the apparent friction coefficient is high (µ>0.4). For the tribofilms containing MoDTC together with ZDTP, which permits the applied pressure to increase up to a few GPa through some accommodation process, a very low friction domain appears (0.01<µ<0.05), located a few nanometers below the surface of the tribofilm. This low friction coefficient is attributed to the presence of MoS 2 planes sliding over each other in a favourable configuration obtained when the pressure is sufficiently high, which is made possible by the presence of ZDTP.

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“…The technical trends in the formulation of fuel economy engine oils are lowering viscosity to reduce hydrodynamic friction, and using friction modifiers to reduce friction in the boundary regime. Molybdenum dithiocarbamates (MoDTCs) are frequently used for the latter, and many studies on the frictional characteristics of MoDTC have been reported to explain the mechnism of reducing friction [1][2][3][4][5][6] . There are several types of MoDTCs, with binuclear MoDTCs known to reduce boundary friction most effectively in engine oil formulations.…”

Section: Introductionmentioning

confidence: 99%

The Investigation of Improvement Effects on Friction Properties of Mononuclear MoDTCs having Azaheterocycles by Episulfidation

et al. 2010

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The effects of episulfidation on the frictional properties of mononuclear molybdenum dithiocarbamates having azaheterocycles were investigated. It was shown that the friction coefficients of the lubricants with the episulfided mononuclear molybdenum dithiocarbamates, as measured by the SRV friction test, were lower than those with non-episulfided ones. The friction coefficients of episulfided compounds are also similar to that of binuclear molybdenum dithiocarbamate, which is frequently used as friction modifier in lubricants in actual practice. The extent of decrease in friction in the SRV test differed with the number of carbon atoms in the azaheterocycles of the molybdenum compounds, suggesting that the thermal stability of the compounds affected the friction characteristics of the tested oils. The results from EPMA surface analyses of the disks from the SRV tests suggest that episulfidation of the molybdenum compounds led to effective formation of molybdenum disulfide film by the corresponding oils during the friction tests.

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Influence of the alkyl group of zinc dialkyldithiophosphate on the frictional characteristics of molybdenum dialkyldithiocarbamate under sliding conditions

Cited by 40 publications

References 10 publications

A methodology for Raman characterisation of MoDTC tribofilms and its application in investigating the influence of surface chemistry on friction performance of MoDTC lubricants

A methodology for Raman characterisation of MoDTC tribofilms and its application in investigating the influence of surface chemistry on friction performance of MoDTC lubricants

Synergistic Effects of MoDTC and ZDTP on Frictional Behaviour of Tribofilms at the Nanometer Scale

The Investigation of Improvement Effects on Friction Properties of Mononuclear MoDTCs having Azaheterocycles by Episulfidation

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