Tribological properties of nanodiamonds in aqueous suspensions: effect of the surface charge

Liu, Zijian; Leininger, Dustin; Koolivand, Amir; Smirnov, Alex I.; Shenderova, Olga; Brenner, Donald W.; Krim, J.

doi:10.1039/c5ra14151f

Cited by 21 publications

(42 citation statements)

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“…Numerous studies of nanoparticulate additives to oil-based systems have been reported in the literature, with many displaying significant improvements in macroscopic friction and wear rates [ 6 ]. Water-based suspensions have received far less attention [ 1 – 2 7 – 9 ]. Although the low shear strength of water is beneficial in the hydrodynamic regime of lubrication, under normal loads it also enables contact between opposing surfaces.…”

Section: Introductionmentioning

confidence: 99%

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

Curtis¹,

Marek²,

Smirnov³

et al. 2017

Beilstein J. Nanotechnol.

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This article reports a comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively (hydroxylated) or negatively (carboxylated) charged nanodiamonds (ND). Immersion in −ND suspensions resulted in a decrease in the macroscopic friction coefficients to values in the range 0.05–0.1 for both stainless steel and alumina, while +ND suspensions yielded an increase in friction for stainless steel contacts but little to no increase for alumina contacts. Quartz crystal microbalance (QCM), atomic force microscopy (AFM) and scanning electron microscopy (SEM) measurements were employed to assess nanoparticle uptake, surface polishing, and resistance to solid–liquid interfacial shear motion. The QCM studies revealed abrupt changes to the surfaces of both alumina and stainless steel upon injection of –ND into the surrounding water environment that are consistent with strong attachment of NDs and/or chemical changes to the surfaces. AFM images of the surfaces indicated slight increases in the surface roughness upon an exposure to both +ND and −ND suspensions. A suggested mechanism for these observations is that carboxylated −NDs from aqueous suspensions are forming robust lubricious deposits on stainless and alumina surfaces that enable gliding of the surfaces through the −ND suspensions with relatively low resistance to shear. In contrast, +ND suspensions are failing to improve tribological performance for either of the surfaces and may have abraded existing protective boundary layers in the case of stainless steel contacts. This study therefore reveals atomic scale details associated with systems that exhibit starkly different macroscale tribological properties, enabling future efforts to predict and design complex lubricant interfaces.

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Section: Introductionmentioning

confidence: 99%

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

Curtis¹,

Marek²,

Smirnov³

et al. 2017

Beilstein J. Nanotechnol.

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“…However, their impact on the performance of existing phosphate ester anti-wear additives is unknown. Several studies of nanodiamond additives have revealed their ability to improve tribological performance in various applications as well as various lubrication regimes including boundary lubrication [11][12][13]. However, their direct influence on the performance of existing additives has not been extensively studied to date.…”

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confidence: 99%

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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“…The energy dissipation of the QCM that can also be related to the quality factor Q of the QCM oscillator, therefore, increases. If the QCM quality factor was Q ≈ 50,000 in air, it would drop to Q ≈ 3280 after immersion in water [7]. Since, the ratio f /R is proportional to the quality factor Q of the QCM oscillator, the relative change in Q factor can be approximated as Q/Q = (f/R)/(f/R), as shown in Figure 1d [33].…”

Section: Quartz Crystal Microbalance Data Analysismentioning

confidence: 99%

“…They are available as manufactured materials with a wide range of surface treatments and have great potential for reducing friction [5]. Reductions or increases in friction coefficients and wear associated with nanoparticles are, however, closely linked to nanoparticle concentration, size, morphology, electrical charge, and the surface treatment employed to prevent agglomeration [6,7]. Given that nanoparticles are also ubiquitous in nature in the form of wear particles resulting from frictional rubbing process [8], studies of their behavior are timely and compelling.…”

Section: Introductionmentioning

confidence: 99%

“…While some NPs provide lubrication for specific substrates, others have little effect or even give rise to additional friction and wear [9]. Given that some nanoparticle suspensions are lubricious in some applications while others are detrimental, the fundamental mechanisms associated with the presence of NP that give rise to macroscale tribological performance is now the major focus of current research [5,7,9]. The results of such studies also have impact on the broader field of ceramic nanoparticles applications in the fields of physics, materials, chemistry, biomedicine, and pharmaceuticals, where knowledge of the interactions of nanoparticles at solid-liquid interfaces is key to progress [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Nanotribological Performance Factors for Aqueous Suspensions of Oxide Nanoparticles and Their Relation to Macroscale Lubricity

Acharya

Pardue

et al. 2019

Lubricants

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Quartz crystal microbalance (QCM) measurements of nanotribological properties of statistically diverse materials combinations of nanoparticles and substrate electrodes in aqueous suspensions are reported and compared to macroscale measurements of the same materials combinations for a subset of the nanoparticle combinations. Four ceramic nanoparticles, TiO , and SS304) were studied. The QCM technique was employed to measure frequency and motional resistance changes upon introduction of nanoparticles into the water surrounding its liquid-facing electrode. This series of experiments expanded prior studies that were often limited to a single nanoparticle -solid liquid combination. The variations in QCM response from one nanoparticle to another are observed to be far greater than the variation from one substrate to another, indicating that the nanoparticles play a larger role than the substrates in determining the frictional drag force levels. The results were categorized according to the direction of the frequency and motional resistance changes and candidate statistical performance factors for the datasets were generated. The performance factors were employed to identify associations between the QCM atomic scale results and the macroscale friction coefficient measurements. Macroscale measurements of friction coefficients for selected systems document that reductions (increases) in motional resistance to shear, as measured by the QCM, are linked to decreases (increases) in macroscale friction coefficients. The performance factors identified in the initial study therefore appear applicable to a broader set of statistically diverse samples. The results facilitate full statistical analyses of the data for identification of candidate materials properties or materials genomes that underlie the performance of nanoparticle systems as lubricants.

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Tribological properties of nanodiamonds in aqueous suspensions: effect of the surface charge

Abstract: The sign of nanodiamond surface charge is discovered to profoundly impact friction at both nanometer and macroscopic scales.

Cited by 21 publications

References 50 publications

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

A comparative study of the nanoscale and macroscale tribological attributes of alumina and stainless steel surfaces immersed in aqueous suspensions of positively or negatively charged nanodiamonds

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

Nanotribological Performance Factors for Aqueous Suspensions of Oxide Nanoparticles and Their Relation to Macroscale Lubricity

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