IR Spectroscopic Analysis of Grease Lubricant Films in Rolling Contacts

Hurley, S.; Cann, P. M.

doi:10.1016/s0167-8922(99)80079-0

Cited by 19 publications

(18 citation statements)

References 2 publications

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“…Although the literature demonstrated the possibility of investigating the chemical composition [23][24][25] and the conformation of the lubricant film [15,26], the pressure distribution within the contact [27] as well as the third bodies formed by solid lubricants in the contact [4][5][6][7][8][9][10][11][12], the necessity of replacing one of surfaces with an IR-transparent window can have significant implications for the study of the tribochemistry of lubricant additives and solid lubricants. Such a requirement was found not to strongly affect the studies of fluid lubricating film behavior performed by infrared micro-reflection spectroscopy: the tribotests, in this case, were carried out in the elasto-hydrodynamic (EHL) regime and, therefore, infrared spectroscopy was not used as a surface-sensitive technique [15,[23][24][25][26][27].…”

Section: Comparison Of the Newly Developed In Situmentioning

confidence: 99%

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In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

2011

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To investigate the chemical changes occurring at metal/lubricant interfaces under tribological conditions in the boundary-lubrication regime, an in situ system for conducting quantitative tribological measurements has been constructed by combining an attenuated total reflection Fourier-transform infrared (ATR/FT-IR) spectrometer with a reciprocating tribometer. By periodically acquiring ATR/FT-IR spectra during sliding, spectroscopic changes due to thermal and/or tribochemical reactions occurring at the metal/oil interface can be monitored and correlated with friction measurements. The usefulness of this tribological test system has been demonstrated by performing ATR tribological experiments in the presence of a poly-α-olefin base oil at high temperature (423 K) on iron-coated germanium ATR crystals

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Section: Comparison Of the Newly Developed In Situmentioning

confidence: 99%

“…Information about the chemical composition [23][24][25], the conformation of the lubricant film [15,26] and the pressure distribution [27] can be gained by carrying out the analysis in the contact region.…”

Section: Introductionmentioning

confidence: 99%

In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

2011

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“…A previous study reported [23] that the reflowed mobile lubricant is mainly base oil bleeding out of grease because of shearing and heating. The different reflowing behaviors of grease and oil were expected to be due to the presence of thickener rather than the reflowed oil.…”

Section: Lubricant Reflowmentioning

confidence: 99%

Effects of nano thickener deposited film on the behaviour of starvation and replenishment of lubricating greases

et al. 2016

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Abstract:The mechanism of grease replenishment in and around a starved point contact was studied in this work. Greases made of different thickeners and same base oil were tested and compared. Disappearing and re-formation of a dynamic grease reservoir during operation revealed that grease bled oil to replenish contact. However, the replenishment process was slow because of the presence of grease fingers along the track and thickener-deposited film inside the track. The contact angles of base oil on the chromium-coated surface and thickener-deposited surfaces were measured. Results proved that the contact angle on the deposited film remarkably increased compared with that on the chromium-coated surface from 25° to more than 40°. However, the deposited film could be consumed with continuous rolling, and replenishment was then enhanced.

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“…The mechanisms leading to the onset of starvation due to insufficient replenishment are explained in Figure 2 [18]. By shearing the grease during operation, bleed oil is released by the side-lying grease bulks and flows into the formed track and is available for the lubrication of the EHD contact [22,23]. The bleed oil is displaced by the rolling element and replenishes behind it, after an over rolling.…”

Section: Introductionmentioning

confidence: 99%

Effect of Over Rolling Frequency on the Film Formation in Grease Lubricated EHD Contacts under Starved Conditions

et al. 2019

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The service life of rolling bearings is significantly affected by the lubricating film formation in elastohydrodynamic (EHD) contacts. Grease lubricated EHD contacts show a film thickness decay from a characteristic rotational speed, which is referred to as starvation. Thus, the film thickness of grease lubricated contacts differs from that of oil lubricated contacts. However, the base oil properties under fully flooded conditions are commonly assumed to estimate the operating lifetime of grease lubricated bearings, which are usually not fully flooded. Hence, this assumption results in an overestimation of the film thickness for rotational speeds in the range of starvation, which can lead to uncertainties in the bearing design. At high rotational speeds, i.e., high over rolling frequencies, starvation is likely to occur, due to insufficient lubricant supply by replenishment behind the rolling element. Therefore, the focus of this contribution is to investigate the effect of over rolling frequency, and thus replenishment time, on the lubricating film formation in starved, grease lubricated EHD contacts. The film thickness measurements were performed on a ball-on-disc tribometer, which was extended by adding a second ball specimen in front of the measuring ball. By varying the angular distance between the two contacts, the lubricant displacement can be controlled, such that the effect of replenishment time on the film formation can be determined. These investigations should help to establish an advanced understanding of the mechanisms of grease lubrication, and encourage future work with a focus on developing a method to predict the film formation in grease lubricated EHD contacts.

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IR Spectroscopic Analysis of Grease Lubricant Films in Rolling Contacts

Cited by 19 publications

References 2 publications

In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

In Situ Attenuated Total Reflection (ATR/FT-IR) Tribometry: A Powerful Tool for Investigating Tribochemistry at the Lubricant–Substrate Interface

Effects of nano thickener deposited film on the behaviour of starvation and replenishment of lubricating greases

Effect of Over Rolling Frequency on the Film Formation in Grease Lubricated EHD Contacts under Starved Conditions

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