In situ, real time studies of thermal reaction film formation temperatures for iron and 304SS surfaces immersed in 5% tricresyl phosphate in base oil

Acharya, Biplav; Pardue, Tyler N.; Avva, K.S.; Krim, J.

doi:10.1016/j.triboint.2018.04.034

Cited by 20 publications

(26 citation statements)

References 49 publications

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“…The QCM responses for both conditions (below the reaction film formation temperatures) followed the trend for the liquid loading with variations in f and R with temperature being primarily due to the temperature dependent viscosity and density of the oil. As reported earlier [19], the sharp increases in δf and δR observed at 210 • C for the 5% TCP on Fe are attributable to the formation of a TCP thermal reaction film on the Fe surface electrode on the QCM. This feature was, however, shifted to a higher temperature of 228 • for the TCP + nanodiamond blend.…”

Section: Qcm Measurementssupporting

confidence: 79%

“…Figure 4 shows the Fe and baked Fe surfaces after the TCP uptake in the absence and presence of nanodiamonds. The baked Fe surface without the nanodiamonds showed no film on it, and the surface appeared similar to that before the TCP uptake (see reference [19]). The other three film forming surfaces showed similar morphologies.…”

Section: Qcm Measurementsmentioning

confidence: 75%

“…The QCM measurement techniques employed here have been previously described in great detail [19,21]. The QCM crystals were housed in a custom made holder and then immersed in oil containing either TCP or a TCP-nanodiamond blend.…”

Section: Methodsmentioning

confidence: 99%

“…Nanodiamonds, as a proposed synergistic additive to phosphate esters, should clearly not have unfavorable effects on the reaction kinetics.To explore this issue, we studied the effects of nanodiamonds on the formation of thermal reaction films on Fe and air baked Fe surfaces by TCP in a dibasic ester basestock. The TCP thermal reaction film formation temperatures in the presence and absence of nanodiamonds were recorded in-situ by monitoring of the reaction film formation on the surfaces using a quartz crystal microbalance (QCM) [19]. We recently reported the in-situ TCP thermal reaction film formation temperatures for Fe to be 210 • C [19].…”

mentioning

confidence: 99%

“…The TCP thermal reaction film formation temperatures in the presence and absence of nanodiamonds were recorded in-situ by monitoring of the reaction film formation on the surfaces using a quartz crystal microbalance (QCM) [19]. We recently reported the in-situ TCP thermal reaction film formation temperatures for Fe to be 210 • C [19]. Fe samples that were baked in air beforehand did not, however, react with TCP to form the thermal reaction film.…”

mentioning

confidence: 99%

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Synergistic Effect of Nanodiamond and Phosphate Ester Anti-Wear Additive Blends

et al. 2018

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Nanodiamonds are known to improve tribological performance when added to lubricants, but their impact on additives that may already be present in the lubricant is poorly documented. Here, we report on a study of their effects on thermal reaction films formed from tricresyl phosphate (TCP) on Fe substrates immersed in a dibasic ester basestock when blended with TCP. Thermal reaction film formation temperatures were recorded in-situ by monitoring the reaction film formation on both Fe and air baked Fe surfaces using a quartz crystal microbalance (QCM). The nanodiamonds were found to raise the thermal reaction film formation temperature by 18 • C, possibly by raising the activation energy for the reaction, but they were not observed to affect the thickness or rate of formation of the films. The nanodiamonds, moreover, were observed to trigger thermal reaction film formation on air baked Fe surfaces that otherwise were highly resistance to reaction film formation. The surface morphology, roughness, and thickness of the thermal reaction films, as measured by atomic force microscopy (AFM), are reported as well as their chemical compositions, as studied with Electron Dispersive X-ray Spectroscopy (EDS). The coefficients of friction measured on the thermal reaction films during dry solid-solid contact are also reported.Lubricants 2018, 6, 56 2 of 14 existing phosphate esters additives, rather than outright replacing them. An appropriate strategy to limit their use levels while also retaining their function is to blend them with a synergistic and environmentally friendly additive. The overarching goal here is to add the synergistic additive without increasing the amount of phosphorus in the system until it is required to do so. This strategy would be completely practical to implement and applicable in various fields, such as aviation, automobiles, manufacturing, defense, etc., that implement a condition-based maintenance schedule [8].Nanomaterials are emerging as environmentally friendly and effective additives for controlling friction and wear in various applications [9]. Several physical mechanisms such as change in friction mode (sliding to rolling), surface polishing/mending, reduction in cohesive forces via layered materials, etc., and chemical mechanisms, including material delivery/transfer for catalysis, tribofilm formation by tribochemical reactions, etc., have been identified as lubrication mechanisms for nanomaterials [10]. However, nanomaterials should also be able to withstand tough environments under EP conditions during boundary lubrication and the high operating temperatures of aircraft engines if they are to be successfully blended with currently used additives. This requires that nanomaterials have, among other properties, a high melting point, high hardness, and favorable chemical reactions to allow rigid bonding onto the surface, together with the anti-wear film produced by the phosphate ester [5].Among the nanomaterials discovered and studied so far, nanodiamonds are the leading candidates from the po...

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Section: Qcm Measurementssupporting

confidence: 79%

Section: Qcm Measurementsmentioning

confidence: 75%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Synergistic Effect of Nanodiamond and Phosphate Ester Anti-Wear Additive Blends

et al. 2018

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QCM Study of Tribotronic Control in Ionic Liquids and Nanoparticle Suspensions

2021

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A quartz crystal microbalance (QCM) technique has been employed to tune friction at liquid-solid interfaces with tribotronic methods employing externally applied electric fields in both nanoparticle suspensions and ionic liquid systems. The setup consists of a QCM immersed in liquid containing electrically charged constituents whose sensing electrode faces a nearby counter electrode. An electric field perpendicular to the QCM surface is created when a potential is applied between the two electrodes, which allows the charged constituents in the surrounding liquid to be repositioned. QCM measurements are able to detect differences in friction under various field conditions, and thus detectably tune the friction in both nanoparticle and ionic liquid systems. The versatility and simplicity of QCM friction measurements render it an ideal tool for the rapidly expanding research area of tribotronics.

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