Behaviour of MoDTC in DLC/DLC and DLC/steel contacts

Vengudusamy, Balasubramaniam; Green, Jonathan H.; Lamb, Gordon D.; Spikes, H. A.

doi:10.1016/j.triboint.2012.04.028

Cited by 95 publications

(68 citation statements)

References 15 publications

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“…The WS 2 compound played the role of friction reducer due to its crystallographic structure. Formation of WS 2 -containing tribolayer was well documented for W-DLC coatings during lubricated sliding at ambient temperature [14] as well as in the temperature range of 50°C -200°C [13], [15], [16], [17], [18], [19]. For example, reactive magnetron sputtered WC-doped hydrogenated DLC coating (having multilayer structure of WC and a-C:H) showed µ~0.055 at ambient temperature due to formation of WS 2 -containing tribolayer [14].…”

Section: Introductionmentioning

confidence: 91%

“…W-doped DLC coatings are most efficient at low temperatures between ambient [14], [19] and ~100°C [15], [16], [17], [18] combined with lubricated conditions. The tribo-mechanism involves the formation of a WS 2 -containing transfer layer by reactions between the coating and the lubricant, which is highly lubricious.…”

Section: Importance Of Combined Mo and W Dopingmentioning

confidence: 99%

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Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Hovsepian

Mandal

Ehiasarian

et al. 2016

Applied Surface Science

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A molybdenum and tungsten doped carbon-based coating (Mo−W−C) was developed in order to provide low friction in boundary lubricated sliding condition at ambient and at high temperature. The Mo−W−C coating showed the lowest friction coefficient among a number of commercially available state-of-the-art DLC coatings at ambient temperature. At elevated temperature (200°C), Mo−W−C coating showed a significant reduction in friction coefficient with sliding distance in contrast to DLC coatings. Raman spectroscopy revealed the importance of combined Mo and W doping for achieving low friction at both ambient and high temperature. The significant decrease in friction and wear rate was attributed to the presence of graphitic carbon debris (from coating) and 'in-situ' formed metal sulphides (WS 2 and MoS 2 , where metals were supplied from coating and sulphur from engine oil) in the transfer layer.

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Section: Introductionmentioning

confidence: 91%

Section: Importance Of Combined Mo and W Dopingmentioning

confidence: 99%

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Hovsepian

Mandal

Ehiasarian

et al. 2016

Applied Surface Science

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“…As mentioned earlier, the effect of MoDTC in increasing wear of DLC coatings has been reported in the literature [16,[18][19][20][21][22][23] however, they mainly used single additive solutions rather than more realistic fully formulated oils. Haque et al [16,18,22,23] reported this effect with MoDTC obtained from multiple sources, suggesting that this phenomenon is independent of the MoDTC molecular structure.…”

Section: Effect Of Mo-fm On A-c:15h Coating Wearmentioning

confidence: 99%

“…Recently, the effect of MoDTC in increasing wear of a DLC coating in a DLC/steel contact has been reported [16,[18][19][20][21][22][23]. Haque et al [16] showed that DLCs rubbed against steel in the presence of a MoDTC-containing base oil gave extremely high wear but that the addition of the antiwear additive ZDDP terminated this effect [16].…”

Section: Introductionmentioning

confidence: 99%

The effect of MoDTC-type friction modifier on the wear performance of a hydrogenated DLC coating

Kosarieh¹,

Morina²,

Lainé³

et al. 2013

Wear

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Abstract:The application of Diamond-Like Carbon (DLC) coatings for automotive components is becoming a promising strategy to cope with the new challenges faced by automotive industries. DLC coatings simultaneously provide low friction and excellent wear resistance which could potentially improve fuel economy and durability of the engine components in contact.The mechanisms by which a non-ferrous material interacts with a variety of lubricant additives is becoming better understood as the research effort in this area increases however there are still significant gaps in the understanding .A better understanding of DLC wear may lead to lubricant additive solutions being tailored for DLC surfaces to provide excellent durability (wear) as well as similar or increased fuel economy (low friction). In this work, the wear and friction properties of DLC coating under boundary lubrication conditions have been investigated.A pin-on-plate tribotester was used to run the experiments using HSS steel plates coated with 15 at.% hydrogenated DLC (a-C:15H) sliding against cast iron pins. One type of fully formulated oil with and without ZDDP and two levels of a MoDTC type friction modifier (Mo-FM) was used in this study. The friction and wear response of the fully formulated oils is discussed in detail.Furthermore, optical and scanning electron microscopes (SEM) were used to observe the wear scar and obtain wear mechanisms. Energy-Dispersive X-ray analysis (EDX) and X-ray Photoelectron Spectroscopy (XPS) analysis were performed on the tribofilms to understand the tribochemical interactions between oil additives and the DLC coating. A nano-indentation study was conducted to observe the changes in the structure of the coating, which can provide a better insight into the wear mode and failure mechanism of such hard coatings.In the light of the physical observations and tribochemical analysis of the wear scar, the wear behaviour of a hydrogenated DLC (a-C:15H) coating was found to depend on the concentration of the MoDTC friction modifier and the wear performance is much better when ZDDP is present in the oil. The tribochemical mechanisms, which contribute to this behaviour, are discussed in this paper.

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“…In addition, DLC coatings have been reported to be chemically inert using a steel pin sliding against DLC-coated disks lubricated in oil containing ZDDP and/or MoDTC [25]. In contrast, in recently published works, molybdenum-based friction modifiers have been reported to form low friction MoS 2 sheets and ZDDPderived compounds were detected on the DLC coating providing low friction and better wear performance under boundary lubrication conditions [26][27][28][29][30][31][32][33]. Therefore, the published results have been found to be contradictory and a comprehensive understanding of DLC tribochemistry is still to be clearly produced.…”

Section: Introductionmentioning

confidence: 99%

Tribological performance and tribochemical processes in a DLC/steel system when lubricated in a fully formulated oil and base oil

Kosarieh

Morina

Lainé

et al. 2013

Surface and Coatings Technology

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Abstract:Diamond-like carbon (DLC) coatings show extremely good promise for a number of applications in automotive components as they exhibit excellent tribological properties such as low friction and good wear resistance. This can impact on improved fuel economy and durability of the engine components. Much work has been reported on the dry sliding of DLC coatings with less so in lubricated contacts and, as such, there is a need to further understand the tribochemistry of lubricated DLC contacts. Commercially-available oils are normally optimized to work on ferrous surfaces. Previous studies on DLC lubricated contacts have tended to use model oil systems rather than fully formulated lubricants and from this an interesting picture of lubrication mechanisms is emerging. Optimising compatibility between a surface and a set of lubricant additives may lead to excellent durability (wear) as well as increased fuel economy (low friction). In this work, the friction and wear properties of a DLC coating under boundary lubrication conditions have been investigated and the tribological performance compared with that of an uncoated steel system. A pin-on-plate tribotester was used to run the experiments using High speed steel (HSS) M2 grade plates coated with 15 at.% hydrogenated DLC (a-C:15H) sliding against cast iron pins. A Group III mineral base oil, fully synthetic Group IV PAO and four different fully formulated oils were used in this study. Furthermore optical and scanning electron microscopes (SEM) were used to observe the wear scar and to assess the durability of the coatings. Energy-Dispersive X-ray analysis (EDX), X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy analyses were performed on the tribofilms to understand the tribochemical interactions between oil additives and the a-C:15H coating.This study show that the durability of the a-C:15H coating strongly depends on the selected additive package in the oils. In addition the effect of detergent, dispersant and antioxidants on the performance of the Molybdenum-based friction modifier (Mo-FM) and ZDDP anti-wear additive were investigated and results are reported in this paper.

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Behaviour of MoDTC in DLC/DLC and DLC/steel contacts

Cited by 95 publications

References 15 publications

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

Friction and wear behaviour of Mo–W doped carbon-based coating during boundary lubricated sliding

The effect of MoDTC-type friction modifier on the wear performance of a hydrogenated DLC coating

Tribological performance and tribochemical processes in a DLC/steel system when lubricated in a fully formulated oil and base oil

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