Imaging of lubricating oil insolubles by electron microscopy

Shuff, P.J.; Clarke, Lionel

doi:10.1016/0301-679x(91)90009-x

Cited by 21 publications

(15 citation statements)

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“…the soap thickener can be observed in both AFM and SEM analysis. Thus, the microstructure of samples C1 and C4 consist of fine, small and slightly entangled and twisted fibres as previously described [13,32], whereas a granular and/or sponge-like thickener microstructure was detected in both AFM and SEM micrographs for samples C2 and C3, when the thickener was dispersed in vegetable-derived oils. However, a certain degree of crosslinked structures can be distinguished for sample C2 in the SEM image taken at the highest magnification (Figure 2).…”

Section: Comparison Between Afm and Sem Imaging Of Lubricating Greasesupporting

confidence: 74%

“…As can be deduced from the microscopy observations previously discussed, the morphology of grease structure greatly depends on the composition, both type of thickener and base oil. The typical morphologies given by the most common thickener agents have been previously reported [4,[13][14][15]18]. However, the influence of either the base oil or the interaction between the base oil and the thickener has not still been and TEM analysis [13][14][15][16].…”

Section: Comparison Between Afm and Sem Imaging Of Lubricating Greasementioning

confidence: 99%

“…Microscopy methods like atomic force microscopy (AFM), scanning electron microscopy (SEM) or transmission electron microscopy (TEM), reveals micro-and nanoscale structural details, and therefore are powerful and effective tools for visualising the lubricating grease morphology [13][14][15][16][17][18]. However, in spite of the continual development and great diversity of microscopy techniques, microstructure determination of lubricating greases remains a current challenge.…”

Section: Introductionmentioning

confidence: 99%

“…Despite the fact that there is a rather extensive literature describing the use of TEM and SEM techniques to investigate the grease microstructure [13,14,16,20], the two techniques present some drawbacks. Both of them are vacuum based and, therefore the oil component must be removed or its volatility reduced before analysis, for instance by freezing the sample.…”

Section: Introductionmentioning

confidence: 99%

“…The typical morphologies given by the most common thickener agents have been previously reported [4,[13][14][15]18]. However, the influence of either the base oil or the interaction between the base oil and the thickener has not still been and TEM analysis [13][14][15][16]. Relatively short, thin and not especially agglomerated fibres can be observed by means of AFM analysis in the case of grease C1.…”

mentioning

confidence: 98%

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AFM and SEM Assessment of Lubricating Grease Microstructures: Influence of Sample Preparation Protocol, Frictional Working Conditions and Composition

2016

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The microstructure of lubricating greases greatly conditions their in-service performance. In that sense, optimal testing protocols are required in order to accomplish their correct morphological characterization. This study explores and compares the suitability of Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) techniques for imaging six different commercial metallic soap-based greases and two novel biopolymer-based formulations. Pros and cons of both techniques as well as the effect of sample preparation protocol were analyzed. The results revealed a wide variety of morphological characteristics depending on composition. Thus, the four anhydrous calcium-based greases demonstrated two clearly distinct microstructures (fibrous and granular) determined by the type of base oil employed. With regard to the lithium complex greases, the typically reported microstructure characterized by welldefined entangled and fibrous network was observed in both AFM and SEM techniques.As for the two biopolymer-based greases, fiber networks were also encountered.Besides this, selected greases were subjected to different tribological tests, and the effect of high-shear frictional working treatments on their microstructure was also analyzed. As a result of the friction and internal wear, the AFM results evidenced microstructural changes which depended on grease composition. Overall, the combined use of AFM and SEM techniques was demonstrated to be a powerful approach to microstructurally characterize lubricating greases.

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Section: Comparison Between Afm and Sem Imaging Of Lubricating Greasesupporting

confidence: 74%

Section: Comparison Between Afm and Sem Imaging Of Lubricating Greasementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 98%

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AFM and SEM Assessment of Lubricating Grease Microstructures: Influence of Sample Preparation Protocol, Frictional Working Conditions and Composition

2016

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Atomic Force Microscopy and Thermo-Rheological Characterisation of Lubricating Greases

et al. 2010

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In this work, non-perturbed microstructures of several commercial and model lubricating greases, differing in nature and concentration of the thickener agent, were examined using the atomic force microscopy (AFM) technique. Grease microstructure mainly depends on the nature of the thickener employed and, also, on thickener concentration and viscosity of the base oil. Thermal-induced changes in the viscoelastic response of lubricating greases have been investigated by using different rheological techniques in a temperature range of 0-175°C. Small-amplitude oscillatory shear (SAOS) measurements were carried out to determine the mechanical spectra of the different samples studied. Lubricating grease rheological thermal susceptibility was analysed by following the evolution of the plateau modulus with temperature. SAOS functions dramatically decrease, in most cases, above a characteristic temperature, which depends on nature and/or concentration of the thickener used and therefore on grease microstructure. The thermo-mechanical reversibility of grease microstructure has been studied by carrying out triple-step-shear stress tests (shear stresses inside and outside of the linear viscoelasticity range), at different temperatures. The degree of lubricating grease non-reversible structural breakdown, which increases with temperature, depends on the shear stress applied above the linear viscoelasticity limits.

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Rheology and microstructure of lithium lubricating greases modified with a reactive diisocyanate-terminated polymer: Influence of polymer addition protocol

Moreno

Valencia

de-Paz

et al. 2008

Chemical Engineering and Processing: Process Intensification

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Imaging of lubricating oil insolubles by electron microscopy

Cited by 21 publications

References 1 publication

AFM and SEM Assessment of Lubricating Grease Microstructures: Influence of Sample Preparation Protocol, Frictional Working Conditions and Composition

AFM and SEM Assessment of Lubricating Grease Microstructures: Influence of Sample Preparation Protocol, Frictional Working Conditions and Composition

Atomic Force Microscopy and Thermo-Rheological Characterisation of Lubricating Greases

Rheology and microstructure of lithium lubricating greases modified with a reactive diisocyanate-terminated polymer: Influence of polymer addition protocol

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