Interfacial Structure and Tribological Property of Adsorbed Layer Formed by Dibasic Acid Ester Derivative

Yamashita, Naoki; Hirayama, Tomoko; Yamada, Norifumi L.; Shimizu, Yutaro; Oda, Kazuhiro; Kawamoto, Hideki

doi:10.2474/trol.17.246

Cited by 4 publications

(3 citation statements)

References 35 publications

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“…Neutron reflectometry is becoming widely used in the field of tribology, but it is mainly used to evaluate the thickness and density of adsorbed additive layers in a static state 8 – 10 . For example, fatty acids such as palmitic and oleic acids were found to form a nanoscale adsorbed layer on Fe, Cu, and diamond-like carbon, with thicknesses roughly equivalent to their molecular chain lengths 11 – 14 . Evaluation of oil-soluble polymeric friction modifiers clarified the temperature dependence of the thickness and density of the adsorbed layer formed under static conditions 1 .…”

Section: Introductionmentioning

confidence: 99%

Neutron reflectometry under high shear in narrow gap for tribology study

Yamashita,

Hirayama,

Hino

et al. 2023

Sci Rep

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An operando analysis method has been established for evaluating the interfacial structure of an adsorbed layer formed by an additive on a metal surface under fluid lubricated conditions. A parallel-face narrow gap viscometer installed in an energy-resolved neutron reflectometer is used to evaluate the change in the interfacial structure under high shear. The viscometer was designed to operate at a high shear rate while maintaining a µm-order constant gap between two parallel surfaces. When an additive-free base oil was sandwiched in the gap, the neutron reflectivity profiles without and with upper surface rotation were the same. This demonstrates that the reflectivity profiles can be accurately measured regardless of whether the upper surface is rotated. When a base oil containing a polymethacrylate-based additive was sandwiched in the gap, both the thickness and density of the adsorbed additive layer in the rotation (shear field) condition were lower than those in the non-rotation (static) condition. This demonstrates that the proposed method can be used to analyse the structural changes in the adsorbed layer formed by an oil additive on a surface. This combination of a neutron reflectometer and narrow gap viscometer is a promising approach to near-future tribological studies.

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Section: Introductionmentioning

confidence: 99%

Neutron reflectometry under high shear in narrow gap for tribology study

Yamashita,

Hirayama,

Hino

et al. 2023

Sci Rep

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“…Liquid lubricants under boundary lubrication reduce friction and wear by forming an adsorption and reaction layer at the friction interface. In recent years, liquid lubricants that form a strong adsorption and reaction layer have been developed [7][8][9][10][11][12]. However, their lubricating properties are not significantly better.…”

Section: Introductionmentioning

confidence: 99%

Effects of Relative Humidity on Lubricating Properties of Ionic Liquids

Kawada

Tanji

Kobayashi

et al. 2023

e-J. Surf. Sci. Nanotechnol.

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Minimizing friction losses in mechanical systems is essential for realizing a low-carbon society, as it will result in energy and resource conservation. In this study, we focused on the suitability of ionic liquids that form an electric double layer for use as liquid lubricants. Ionic liquids have been reported to exhibit ultralow friction with friction coefficients of less than 0.01. However, it is necessary to elucidate the effects of water on their lubricating properties, as water can cause corrosive wear on metallic sliding materials during lubrication using fluorine-based ionic liquids. In addition, water destroys the layer formed at the friction interface and adversely affects the lubricating properties. Here, we investigated the lubricating properties and lubricating mechanisms of both hydrophilic (1-butyl-3-methylimidazolium dicyanamide [BMIM][DCN] and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF 4 ]), and hydrophobic (1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF 6 ] and 1butyl-3-methylimidazolium tris (perfluoroalkyl) trifluorophosphate [BMIM][FAP]) ionic liquids at different relative humidity (RH) levels (15, 50, and 80%). [BMIM][DCN] exhibited good lubricating properties at 15% RH because of the formation of an adsorption layer derived from both types of ions. However, the adsorption layer was destroyed by water molecules as the humidity was increased. [BMIM][BF 4 ] also exhibited good lubricating properties at 15% RH. This ionic liquid formed a chemical layer as well as an adsorption layer. However, these layers were destroyed by water molecules at 50 and 80% RH. In the case of [BMIM][PF 6 ] too, a chemical layer and an adsorption layer were formed at 15 and 50% RH, and these layers exhibited the best lubricating properties. On the other hand, the layers were destroyed by water molecules at 80% RH. Finally, [BMIM][FAP] exhibited good lubricating properties even under high-RH conditions because this ionic liquid was the most hydrophobic.

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“…Neutron re ectometry is becoming widely used in the eld of tribology, but it is mainly used to evaluate the thickness and density of adsorbed additive layers in a static state [8][9][10] . For example, fatty acids such as palmitic and oleic acids were found to form a nanoscale adsorbed layer on Fe, Cu, and diamond-like carbon, with thicknesses roughly equivalent to their molecular chain lengths [11][12][13][14] . Regarding for polymer additives, the temperature dependence of the thickness and density of the adsorbed layer formed under static states has been evaluated 1 .…”

Section: Introductionmentioning

confidence: 99%

Neutron Reflectometry under High Shear in Narrow Gap for Tribology Study

Yamashita

Hirayama

Hino

et al. 2023

Preprint

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A parallel-face narrow gap viscometer was installed in the energy-resolved neutron reflectometer to investigate the change in interfacial structure under high shear. The viscometer was designed to operate with high shear rate while maintaining a µm-order constant gap between two parallel faces. When the base oil without any additives was sandwiched in the gap of viscometer, the neutron reflectivity profiles without and with the rotation of viscometer was the same. This result shows that correct measurements were performed regardless of whether the upper specimen was rotated or not. On the other hand, when the base oil containing polymethacrylate-type additive was sandwiched in the gap, both the thickness and density of adsorbed additive layer in shear field became lower than that in stay condition. The results demonstrate that the proposed method can be used to analyse the structural changes in the adsorbed layer formed by the additive on the surface. Such approaches with the combination of neutron reflectometer and narrow gap viscometer are promising for near-future tribology studies.

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Interfacial Structure and Tribological Property of Adsorbed Layer Formed by Dibasic Acid Ester Derivative

Cited by 4 publications

References 35 publications

Neutron reflectometry under high shear in narrow gap for tribology study

Neutron reflectometry under high shear in narrow gap for tribology study

Effects of Relative Humidity on Lubricating Properties of Ionic Liquids

Neutron Reflectometry under High Shear in Narrow Gap for Tribology Study

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