High-Performance Heterocyclic Friction Modifiers for Boundary Lubrication

Desanker, Michael; He, Xingyao; Lü, Jie; Johnson, Bernadette; Liu, Zhong; Delferro, Massimiliano; Ren, Nanqi; Lockwood, Frances E.; Greco, Aaron; Erdemir, Ali; Marks, Tobin J.; Wang, Q Jane; Chung, Yip‐Wah

doi:10.1007/s11249-018-0996-z

Cited by 14 publications

(18 citation statements)

References 54 publications

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“…According to the λ ratio listed in Table , the friction experiments involved in this paper were all under the state of the boundary lubrication condition. where R a1 and R a2 are the roughnesses of the friction surface and h c for a point contact (eq ) is the central film thickness obtained using the Dowson and Hamrock equation where α is the pressure–viscosity coefficient, E ′ is the effective elastic modulus of the contacted solid bodies, η is the lubricant viscosity under the ambient condition, U is the velocity, R e is the effective radius of the contact, F is the normal load, L is the length of the cylinder pin, and k is the contact ellipticity parameter, which is 1 for the current case.…”

Section: Methodsmentioning

confidence: 99%

“…where α is the pressure−viscosity coefficient, 11 E′ is the effective elastic modulus of the contacted solid bodies, η is the lubricant viscosity under the ambient condition, U is the velocity, R e is the effective radius of the contact, F is the normal load, L is the length of the cylinder pin, and k is the contact ellipticity parameter, which is 1 for the current case. Investigation of the Worn Surface.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…FMs are mainly organic − and inorganic, − both of which are widely applied in engine oils to reduce friction and wear under boundary lubrication conditions. FMs used in engines should be free of sulfur or phosphorus because they may damage the three-way catalytic converters and adversely affect the emission control system of vehicles .…”

Section: Introductionmentioning

confidence: 99%

“…To date, much efforts have involved exploring FMs with multiple polar groups to more resilient boundary lubrication films. Desanker et al , have reported a series of nitrogen heterocyclic FMs that can enhance surface adsorption through the chelate effect. The FMs exhibited excellent thermal and hydrolytic stability, as well as exceptional low friction functionality in the boundary lubrication regime.…”

Section: Introductionmentioning

confidence: 99%

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Alkyl-Ethylene Amines as Effective Organic Friction Modifiers for the Boundary Lubrication Regime

Zeng

et al. 2020

Langmuir

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With the pursuit of fuel economy in the automotive industry, recently low-viscosity lubricant technology has been widely improved. The present work has systematically discussed a series of sulfur- and phosphorus-free organic friction modifiers (FMs)alkyl-ethylene aminesby alkyl substitution from ethylene amines with various nitrogen-atom numbers and molecular configurations. Herein, the pin-on-flat reciprocation friction tests have exhibited that the addition of the novel alkyl-ethylene amines into base oil led to significant reductions in the friction coefficient (up to 23%). Further investigations of tribological properties at elevated temperatures demonstrated that the increased number of nitrogen atoms and the regular linear atomic arrangement contributed to an improvement of friction reduction (up to 66%) compared to the neat base oil. Notably, results of water contact angle measurement and infrared spectroscopy (IR) have provided favorable evidence that the novel FMs have adsorbed on the metal surface leading to the formation of a tribofilm, whereby the tribofilm prevented the sliding surfaces from direct asperity contact and markedly improved the tribological performance, as seen from the composition analysis of the worn surfaces by an energy-dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), and confocal Raman spectroscopy. Therefore, the present work can provide a practical reference for molecular structure design through investigation of structure–performance relations of lubricant additives.

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Section: Methodsmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Alkyl-Ethylene Amines as Effective Organic Friction Modifiers for the Boundary Lubrication Regime

Zeng

et al. 2020

Langmuir

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“…Currently, there are four main types of FMs that can be used in engine oil: (1) organic molybdenum compounds, − (2) organic friction modifiers (OFMs), − (3) functionalized polymers, − and (4) nanoparticles. − Among the above-mentioned FMs, organic molybdenum compounds can provide significant performance benefits including antioxidation, friction reduction, and wear protection to the lubricating oil. However, the use of traditional molybdenum additives either at higher threat rates or in certain formulations has been limited by copper and lead corrosion concerns.…”

Section: Introductionmentioning

confidence: 99%

Correlation between the Degree of Alkylation and Tribological Properties of Amino-PEG2-amine-Based Organic Friction Modifiers

Zhang

Zeng

et al. 2019

Ind. Eng. Chem. Res.

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The pursuit of fuel economy in the automobile industry continuously drives the development of low-viscosity lubricants. The present article reports the application of amino-PEG2-amine and its two N,N′-n-octyl-substituted derivatives as friction modifiers, which play a key role in low-viscosity lubricants. The diaminebased friction modifiers with multiple oxygen and nitrogen binding sites exhibit varying tribological properties relying on the degree of alkylation. Amino-PEG2amine exhibits relatively superior wear resistance versus base oil, while the disubstituted secondary diamine turns out to be optimal in friction reduction. Detailed investigations at elevated temperatures demonstrate that the secondary diamine outperforms the two other diamines in friction reduction and maintains stable tribological properties over the whole temperature range. Molecular structure analysis and electron density calculation suggest that the effect of alkylation degree on electron density and steric hindrance has a direct impact on surface adsorption, leading to diverse tribological performance.

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Molecules with a TEMPO-based head group as high-performance organic friction modifiers

et al. 2022

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High-performance organic friction modifiers (OFMs) added to lubricating oils are crucial for reducing energy loss and carbon footprint. To establish a new class of OFMs, we measured the friction and wear properties of N-(2,2,6,6-tetramethyl-1-oxyl-4-piperidinyl)dodecaneamide referred to as C12Amide-TEMPO. The effect of its head group chemistry, which is characterized by a rigid six-membered ring sandwiched by an amide group and a terminal free oxygen radical, was also investigated with both experiments and quantum mechanical (QM) calculations. The measurement results show that C12Amide-TEMPO outperforms the conventional OFMs of glyceryl monooleate (GMO) and stearic acid, particularly for load-carrying capacity, wear reduction, and stability of friction over time. The friction and wear reduction effect of C12Amide-TEMPO is also greatly superior to those of C12Ester-TEMPO and C12Amino-TEMPO, in which ester and amino groups replace the amide group, highlighting the critical role of the amide group. The QM calculation results suggest that, in contrast to C12Ester-TEMPO, C12Amino-TEMPO, and the conventional OFMs of GMO and stearic acid, C12Amide-TEMPO can form effective boundary films on iron oxide surfaces with a unique double-layer structure: a strong surface adsorption layer owing to the chemical interactions of the amide oxygen and free radical with iron oxide surfaces, and an upper layer owing to the interlayer hydrogen-bonding between the amide hydrogen and free radical or between the amide hydrogen and oxygen. Moreover, the intralayer hydrogen-bonding in each of the two layers is also possible. We suggest that in addition to strong surface adsorption, the interlayer and intralayer hydrogen-bonding also increases the strength of the boundary films by enhancing the cohesion strength, thereby resulting in the high tribological performance of C12Amide-TEMPO. The findings in this study are expected to provide new hints for the optimal molecular design of OFMs.

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High-Performance Heterocyclic Friction Modifiers for Boundary Lubrication

Cited by 14 publications

References 54 publications

Alkyl-Ethylene Amines as Effective Organic Friction Modifiers for the Boundary Lubrication Regime

Alkyl-Ethylene Amines as Effective Organic Friction Modifiers for the Boundary Lubrication Regime

Correlation between the Degree of Alkylation and Tribological Properties of Amino-PEG2-amine-Based Organic Friction Modifiers

Molecules with a TEMPO-based head group as high-performance organic friction modifiers

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