Study of Surface Films of the ZDDP and the MoDTC with Crystalline and Amorphous Overbased Calcium Sulfonates by XPS

Costello, Michael T.; Urrego, Roberto A.

doi:10.1080/10402000701271051

Cited by 16 publications

(10 citation statements)

References 16 publications

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“…However, interactions between MoDTC and other common engine oil additives, like detergents or dispersants, are much less understood. Some studies reported a positive detergent/dispersant interaction with MoDTC [20,21], whereas negative effects were identified in others studies [22,23].…”

Section: Introductionmentioning

confidence: 99%

MoDTC Tribochemistry in Steel/Steel and Steel/Diamond-Like-Carbon Systems Lubricated With Model Lubricants and Fully Formulated Engine Oils

Espejo

Thiébaut²,

Jarnias³

et al. 2018

Journal of Tribology

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This work focuses on the tribochemistry of molybdenum dithiocarbamate (MoDTC) oil additive to improve friction behavior of diamond-like-carbon (DLC) coated systems lubricated in boundary regime. Raman microscopy has been used to investigate surface tribolayers formed on coated (hydrogenated a-C:H and non-hydrogenated ta-C) and steel surfaces when lubricated with model lubricants and commercial engine oils. The effect of the additive package and the type of DLC played a crucial role in the development and composition of the tribolayer and the friction performance. The additive package contained in the fully formulated (FF) oils limited the friction reduction capabilities of MoDTC additive for every material pair. Accelerated a-C:H coating wear related to MoDTC tribochemistry was found. For the first time, it has been shown that a distinctive MoS2-containing tribolayer can be formed on the ta-C surface, leading to a coefficient of friction lower than 0.04. The underlying mechanisms of MoDTC/surface interactions and their effect on friction and wear are discussed.

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Section: Introductionmentioning

confidence: 99%

MoDTC Tribochemistry in Steel/Steel and Steel/Diamond-Like-Carbon Systems Lubricated With Model Lubricants and Fully Formulated Engine Oils

Espejo

Thiébaut²,

Jarnias³

et al. 2018

Journal of Tribology

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“…Oil A contains MoDTP friction modifier and calcium sulphonate detergent, the presence of calcium strictly on the wear scar implies that the detergent is surface active and contributes to the tribofilm formed. Previous study on the interaction of calcium sulphonate and organomolybdenum compound showed that the tribofilm formed contained MoS 2 and CaCO 3 [29]. Wei and Song report a synergistic effect that leads to reduce wear [30].…”

Section: Influence Of Bulk Oil Temperaturementioning

confidence: 96%

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

et al. 2020

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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.

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“…An argon etching process was conducted using an ion gun (beam energy, 4 keV; diameter, 1 mm) to evaluate the tribofilm thickness and depth profile. Narrow-scan XPS spectra were acquired after each cycle of the etching process, which was conducted for 0, 1, 3, 6, 10, 30, 50, 100, 200, and 400 s. Casa XPS software was used to fit the obtained peaks and the peaks were assigned in reference to the online database [28] and several previous reports [10,25,29]. Quantification was made by referring to relative sensitive factors.…”

Section: Surface Analysismentioning

confidence: 99%

“…Ma et al reported that calcium-containing detergents synergistically react with MoDTC and ZDDP at the steel-steel contact to form a durable tribofilm [24]. On the other hand, other researchers have concluded that the interaction of calcium sulfonates is antagonistic toward film formation [25][26][27]. These works suggest that the performance of MoDTC/ZDDP is affected either positively or negatively by other additives in fully formulated conditions, even at steel surfaces.…”

Section: Introductionmentioning

confidence: 99%

Friction and Wear Properties of Hard Coatings on Steel Surfaces under Lubrication with a Fully Formulated Oil with a Mo Additive

et al. 2021

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When various sliding components of combustion engines protected with hard coatings are slid with automotive lubricants, unexpected interfacial phenomena may occur because typical automotive lubricants have been formulated with additives suitable for steel/steel sliding components. Therefore, understanding the effects of hard coatings on the performance of lubricant additives is crucial for further improving the lubrication properties of fully formulated oils through the optimization of additive formulations for hard coatings. In this study, friction tests were performed with a steel surface against steel surfaces coated with two ceramic materials and two diamond-like carbon materials under lubrication with a fully formulated oil. Atomic force microscopy and X-ray photoelectron spectroscopic (XPS) investigation of the steel surfaces after the friction tests revealed that the tribofilms comprised a bottom layer composed of calcium compounds and a top layer composed of phosphorous, zinc, and sulfur compounds. The thickness of each layer, which is closely related to the wear property, depends on the hard coating material. Moreover, XPS analysis focusing on the molybdenum element suggested that rate of chemical kinetics to form MoS 2 differs among the hard coating materials, and dominantly affects the frictional property.

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Study of Surface Films of the ZDDP and the MoDTC with Crystalline and Amorphous Overbased Calcium Sulfonates by XPS

Cited by 16 publications

References 16 publications

MoDTC Tribochemistry in Steel/Steel and Steel/Diamond-Like-Carbon Systems Lubricated With Model Lubricants and Fully Formulated Engine Oils

MoDTC Tribochemistry in Steel/Steel and Steel/Diamond-Like-Carbon Systems Lubricated With Model Lubricants and Fully Formulated Engine Oils

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

Friction and Wear Properties of Hard Coatings on Steel Surfaces under Lubrication with a Fully Formulated Oil with a Mo Additive

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