New insights on the decomposition mechanism of Molybdenum DialkyldiThioCarbamate (MoDTC): a Raman spectroscopic study

Khaemba, Doris N.; Neville, Anne; Morina, Ardian

doi:10.1039/c6ra00652c

Cited by 75 publications

(106 citation statements)

References 62 publications

(95 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Mo-Oxide Species could be related to formation of Iron molybdates species. It has been previously shown that ferrous surfaces participate in the decomposition of MoDTC by reacting with the decomposition products to form FeMoO 4 [22]. Higher intensity of the Mo detected is an indication of a more MoDTC-derived tribofilm on the wear scar.…”

Section: Low-friction Film Formationmentioning

confidence: 91%

“…This would explain why there was minimal wear, and no friction reduction, when DLC was tested with a ceramic counterpart. Generally, one or combination of the following mechanisms can be expected for the DLC wear process: (1) MoDTC-derived MoO 3 or iron oxide particles from the ferrous counterpart promote abrasive wear of the DLC coating, (2) moly-oxides (molybdates) formed under tribological conditions [22] act as the catalyst for oxidation of or/and dehydrogenation of the DLC coating [27].…”

Section: Mechanism Of Modtc-induced Wear Of Dlcmentioning

confidence: 99%

See 1 more Smart Citation

Wear Mechanisms of Hydrogenated DLC in Oils Containing MoDTC

et al. 2016

Self Cite

View full text Add to dashboard Cite

Diamond-Like Carbon (DLC) coatings are well known for offering excellent tribological properties. They have been shown to offer low friction and outstanding wear performance in both dry and lubricated conditions. Application of these coatings for automotive components is considered as a promising strategy to cope with the emerging requirements regarding fuel economy and durability. Commercially available oils are generally optimised to work on conventional ferrous surfaces and are not necessarily effective in lubricating non-ferrous surfaces. Recently, the adverse effect of the Molybdenum DialkyldithioCarbamate (MoDTC) friction modifier additive on the wear performance of the hydrogenated DLC has been reported. However, the mechanisms by which MoDTC imposes this high wear to DLC are not yet well understood. A better understanding of DLC wear may potentially lead to better compatibility between DLC surfaces and current additive technology being achieved. In this work, the wear properties of DLC coatings in the DLC/cast iron (CI) system under boundary lubrication conditions have been investigated to try to understand what appears to be a tribocorrosion-type process. A pin-on-plate tribotester was used to run the experiments using High Speed Steel (HSS) plates coated with 15 at.% hydrogenated DLC (a-C:15H) sliding against CI pins or ceramic balls. The lubricants used in this study are typical examples of the same fully formulated oil with and without ZDDP. The friction and wear responses of the fully formulated oils are discussed in detail. Furthermore, Optical Microscopy (OM) and Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray spectroscopy (EDX), Focused Ion Beam (FIB) and Transmission Electron Microscopy (TEM) were used to observe the wear scar and propose wear mechanisms. The X-ray Photoelectron Spectroscopy (XPS) analysis was performed on the tribofilms to understand the tribochemical interactions between oil additives and the DLC coating. Nano-indentation analysis was conducted to assess potential structural modifications of the DLC coating. Coating hardness data could provide a better insight into the wear mode and failure mechanism of such hard coatings. Given the obtained results, the wear behaviour of the hydrogenated DLC coating was found to depend not only on the presence of ZDDP in the oil formulation but also on the counterpart type. This study revealed that the steel counterpart is a critical component of the tribocouple leading to MoDTC-induced wear of the hydrogenated DLC.

show abstract

Section: Low-friction Film Formationmentioning

confidence: 91%

Section: Mechanism Of Modtc-induced Wear Of Dlcmentioning

confidence: 99%

Wear Mechanisms of Hydrogenated DLC in Oils Containing MoDTC

et al. 2016

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, MoS2 can be formed from MoSx either through increasing the energy at the contact by increasing temperature or increasing shear stress.  FeMoO4 is formed from a reaction of iron oxides on the steel surfaces with MoSx [17]. The figure 4 shows a graphical representation for this proposed reaction.…”

Section: Organo-molybdenum Friction Modifiersmentioning

confidence: 99%

“…The figure 4 shows a graphical representation for this proposed reaction. Khaemba et al [17] proposed that the reaction initiates with molecule adsorption on the surface. But, analyzing the work of De Feo [18] it is possible to conclude that a thermal breakdown could occur before the molecule to absorb on the surface, despite he doesn't concluded that.…”

Section: Organo-molybdenum Friction Modifiersmentioning

confidence: 99%

Simulation of Piston Ring/Cylinder Bore System Using Tribotests - A Review Focused on the Tribochemical Aspect

Siebert

Sinatora

2016

SAE Technical Paper Series

View full text Add to dashboard Cite

The growing use of tribotest has been helping the researches to understand the actuation mechanisms of additives on the friction and wear control of engine parts. But, it is common to observe differences between the tribofilms formed in real situation from that obtained using tribotests. Furthermore, the automakers have difficulty to correlate the results obtained using tribotests with that performed using engines in dynamometers. For the piston ring/cylinder bore tribosystem is almost impossible to reproduce its real tribosystem using tribotests. Therefore simplifications are necessary and they affect the tribochemical behavior of the tribosystem. To understand how these simplifications and the test parameters affect the tribochemical behavior of the simplified tribosystem is critical to design a tribotest that correlate well with the real situation.

show abstract

“…The nature of the tribofilm formed from a lubricant is in turn influenced by the operating parameters such as temperature, contact pressure, sliding speed, additive mix amongst other factors [11][12][13][14][15]. Temperature generally increases the chemical and physical interaction of the additives with the surface [4,16].…”

Section: Introductionmentioning

confidence: 99%

Industrial Gear Oils: Influence of Bulk Oil Temperature and Contact Pressure on Tribological Performance and Subsurface Changes

et al. 2020

View full text Add to dashboard Cite

This study was designed to investigate the influence of oil temperature and contact pressure on the tribological performance of three industrial gear oils but also on the corresponding changes taking place beneath the metal surfaces in contact. The result shows that increase in the oil temperature and contact pressure increases surface-additive interaction, promoting the formation of low-friction tribofilms. Subsurface characterisation of the worn surfaces shows that higher oil temperature and contact pressure promotes surface hardening of spheroidised AISI 52100 steel, degradation of the near-surface (< 0.8 µm) microstructural integrity and corresponds to an increase in wear. This study clearly shows that the gear oil formulations and the tribofilms they form uniquely influence the extent of subsurface deformation and wear.

show abstract

New insights on the decomposition mechanism of Molybdenum DialkyldiThioCarbamate (MoDTC): a Raman spectroscopic study

Abstract: Molybdenum DialkyldiThioCarbamate (MoDTC) is a friction modifier that has been used in automotive engines for many years. However, its exact decomposition mechanism within tribocontacts is not fully understood. In this study, an attempt has been made towards

Cited by 75 publications

References 62 publications

Wear Mechanisms of Hydrogenated DLC in Oils Containing MoDTC

Wear Mechanisms of Hydrogenated DLC in Oils Containing MoDTC

Simulation of Piston Ring/Cylinder Bore System Using Tribotests - A Review Focused on the Tribochemical Aspect

Industrial Gear Oils: Influence of Bulk Oil Temperature and Contact Pressure on Tribological Performance and Subsurface Changes

Contact Info

Product

Resources

About