Structural changes in lubricating greases and their mixtures during service

Vámos, Endre; Szamos, J.; Bede, Gy.

doi:10.1016/0043-1648(73)90071-9

Cited by 3 publications

(2 citation statements)

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“…As previously reported, the structural degradation greatly influences the bulk rheology [7,18,20] and the effect of friction on grease structure is referred as rheological wear [33][34][35]. The influence of frictional tests on the microstructure of three selected lubricating greases was investigated using the AFM technique as can be seen in Figure 5.…”

Section: Frictional Working-induced Microstructural Degradationmentioning

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%

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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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