Surface‐Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

Chua, Wenhsi; Chapman, Peter; Stachowiak, Gwidon

doi:10.1007/s11746-012-2075-1

Cited by 6 publications

(6 citation statements)

References 45 publications

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“…The appearance of peaks at 930, 1410, and 1546 cm −1 indicates that the fatty acids react with the metal surface, forming iron carboxylate structures or a metallic soap layer. 58–60 Furthermore, Raman peaks at 1337 cm −1 and 1591 cm −1 corresponded to the D (1300–1380 cm −1 ) and G (1570–1600 cm −1 ) bands. The existence of both the D and G peaks suggested the presence of a carbon layer on the metal surface as a consequence of the base lubricant's tribochemical interaction with the metal surface.…”

Section: Resultsmentioning

confidence: 96%

“…It has been found that the existence of peaks between 2800 and 3000 cm −1 suggests that fatty acid molecule adsorption on the steel surface was generally highly disordered and less densely packed. 59 Furthermore, the peak heights of the PKO + CG nanolubricant's principal Raman peaks, particularly the D and G bands, were more visible than those of the PKO base lubricant, showing that CG had entered the sliding contact. It was clear that graphitic carbon tribofilms were forming since the G peak of the PKO + CG nanolubricant was more intense than it was for PKO.…”

Section: Tribological Characterisationmentioning

confidence: 97%

“…62 The increase in the Raman signal at 1704 cm −1 gives support for the presence of unabsorbed fatty acids at the surface. 59 Despite the fact that the metallic soap film of PKO + CG nanolubricant was lower than that of PKO, the film was more ordered and closely packed since the peak of 2852 cm −1 was lower than the peak of 2847 cm −1 . It has been found that the existence of peaks between 2800 and 3000 cm −1 suggests that fatty acid molecule adsorption on the steel surface was generally highly disordered and less densely packed.…”

Section: Tribological Characterisationmentioning

confidence: 98%

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The role of oleic acid on the structural changes of graphite nanoplatelets in enhancing the tribological performance of a palm oil-based lubricant

Azman

Samion

Musa

2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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The current work investigates the structural changes of graphite (CG) when employed as an additive in palm kernel oil (PKO)-based nanolubricants without and with oleic acid (OA) surfactant. A four-ball tribotester was used to study the tribological performance of PKO + CG nanolubricants. PKO + CG nanolubricants with OA surfactant outperformed others, demonstrating significant reductions in coefficient of friction (20.5%) and wear scar diameter (9.1%) as compared to the PKO base lubricant. Exfoliation of graphite was facilitated during sliding due to the impact of shear force. A transmission electron microscopy structural study showed that the presence of OA surfactant in nanolubricants stimulated the formation of highly exfoliated graphite, resulting in the formation of scrolling graphite. Furthermore, when lubricated with PKO + CG + OA nanolubricants, Raman spectroscopic study of the worn surface reveals the formation of a more ordered tribofilm at the friction contact. The findings highlight graphite structural changes as the major factor in improving tribological performance. These results could help us learn more about the main mechanism of graphite as a lubricant additive and how structural changes affect tribological performance.

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Section: Resultsmentioning

confidence: 96%

Section: Tribological Characterisationmentioning

confidence: 97%

Section: Tribological Characterisationmentioning

confidence: 98%

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The role of oleic acid on the structural changes of graphite nanoplatelets in enhancing the tribological performance of a palm oil-based lubricant

Azman

Samion

Musa

2022

Proceedings of the Institution of Mechanical Engineers, Part J:

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“…It has been initially expected that the film growth may be related to the degree of saturation, since highly unsaturated oils are theoretically more thermally unstable, thus having a greater potential for film growth. Chua et al used SERS to study tribo-chemically induced boundary films formed by refined and unrefined rapeseed oil ( Figure 4) [59]. To the best of our knowledge, this was the first time that SERS has been used to study surface films on metal surface lubricated by vegetable oil.…”

Section: Application Of Sers In Interface Tribology Reaction Detectionmentioning

confidence: 99%

Surface- and Tip-Enhanced Raman Scattering in Tribology and Lubricant Detection—A Prospective

Zhang

Rosenkranz

et al. 2019

Lubricants

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Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) are fast, convenient, and non-destructive molecular detection techniques, which provide a practical method for studying interfacial reactions with high resolution and accuracy. Both techniques are able to provide quantitative and qualitative information on the chemical properties, conformational changes, order state, and molecular orientation of various surfaces. This paper aims at summarizing the research efforts in the field of SERS and TERS related to tribological systems with a special emphasis on thin film and nanoparticles. This overview starts with a brief introduction for both techniques. Afterwards, it summarizes pros and cons of both techniques related to the advanced characterization of tribologically induced reactions layers. Moreover, the feasibility of both techniques to evaluate the friction and wear performance of new lubricant additives including solid lubricants is discussed. At the end of this review article, the main challenges and future directions in this field are prospected to emphasize the development direction of SERS and TERS in tribology and lubricants. Lubricants 2019, 7, 81 2 of 16For this purpose and depending on the material used, various techniques including white light interferometry and laser scanning microscopy (surface topography), Raman spectroscopy, Sum frequency generation (SFG) spectroscopy, X-ray photoelectron spectroscopy and infrared-spectroscopy (surface chemistry) as well as X-ray diffraction, electron backscatter diffraction and transmission electron microscopy (microstructure) can be utilized. It needs to be emphasized that a multi-method approach is recommendable since only one characterization technique will never be able to reveal the full picture regarding the desired information [12].Apart from the fact that there is no powerful in-situ characterization technique to assess any of this information during sliding/rubbing, the entire situation is further complicated since friction and wear are influenced by effects on different scales ranging from macro-to nanoscale [13,14]. Regarding the macro-scale, fabrication tolerances and design aspects can be named as potential effects influencing the resulting coefficient of friction and wear. Related to the micron-scale, the surface topography and surface roughness mainly affect the resulting nominal and real contact area [15]. In this regard, it must be emphasized that the real contact happens at the asperity level, which is typically sub-micron and on the nanoscale. The contact at the asperity level typically induces rather high contact pressure. This can lead to pressure-induced reactions thus generating sub-surface reaction layers, which may substantially influence the corresponding tribological properties [16]. These aspects unambiguously underline that the effects occurring at the nanoscale also significantly alter the resulting friction and wear performance. Consequently, the aforementioned surface topography, surface chemistry, and m...

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“…It was shown that during friction, fatty acids were released from the triglyceride structure of vegetable oils and adsorbed on the surface of the spheres. The fatty acid chains of unrefined rapeseed oil were more disordered than those of refined oil [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

The Use of Raman Spectroscopy to Monitor Changes in the Intensity of Ratio of Integral Unsaturated Bands in Bio-Greases

et al. 2023

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Bio-greases were developed on the basis of vegetable oil obtained from Crambe Abyssinic seeds. An important aspect of this research is to monitor changes in their quality taking place under the influence of external factors. Raman spectroscopy was used to identify changes taking place in the bio-lubricant under the influence of mechanical and thermal forces. The performed tests reflected the operating temperature and friction load that may occur during actual operating conditions for the lubricated friction systems. The Raman spectra provided information on qualitative changes in the structure of the tested bio-lubricants at the molecular level. The integral intensity of the bands used to assess the degree of lipid unsaturation was adopted as the evaluation criterion. The influence of the oxidation process under the PetroOxy and wear test conditions on changes in the structure of the bio-lubricants was assessed. Variation in the integral intensity of the bands (I1655/I1440) proves that the structure of vegetable lubricants changes under the influence of the tests performed. Thermal and mechanical forces influence, the bands originating in unsaturated and result in a decrease in the oxidation resistance of vegetable lubricants.

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Surface‐Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

Cited by 6 publications

References 45 publications

The role of oleic acid on the structural changes of graphite nanoplatelets in enhancing the tribological performance of a palm oil-based lubricant

The role of oleic acid on the structural changes of graphite nanoplatelets in enhancing the tribological performance of a palm oil-based lubricant

Surface- and Tip-Enhanced Raman Scattering in Tribology and Lubricant Detection—A Prospective

The Use of Raman Spectroscopy to Monitor Changes in the Intensity of Ratio of Integral Unsaturated Bands in Bio-Greases

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