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Results for “LUBRICATION”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS2013

The Chevron Foil Thrust Bearing: Improved Performance Through Passive Thermal Management and Effective Lubricant Mixing

An improved foil thrust bearing is described that eliminates or reduces the need for forced cooling of the bearing foils while at the same time improves the load capacity of the bearing, enhances damping, provides overload tolerance, and eliminates the high speed load capacity drop-off that plagues the current state of the art. The performance improvement demonstrated by the chevron foil thrust bearing stems from a novel trailing edge shape that splays the hot lubricant in the thin film radially, thus preventing hot lubricant carry-over into the ensuing bearing sector. Additionally, the chevron shaped trailing edge induces vortical mixing of the hot lubricant with the gas that is naturally resident within the inter-pad region of a foil thrust bearing. The elimination of hot gas carry-over in combination with the enhanced mixing has enabled a completely passive thermally managed foil bearing design. Laboratory testing at NASA has confirmed the original analysis and reduced this concept to practice.

foil bearing↗
DOE OSTI2018

Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives

An ionic liquid composition having the following generic structural formula: ##STR00001## wherein R 1 , R 2 , R 3 , and R 4 are equivalent and selected from hydrocarbon groups containing at least three carbon atoms, and X - is a phosphorus-containing anion, particularly an organophosphate, organophosphonate, or organophosphinate anion, or a thio-substituted analog thereof containing hydrocarbon groups with at least three carbon atoms. Also described are lubricant compositions comprising the above ionic liquid and a base oil, wherein the ionic liquid is dissolved in the base oil. Further described are methods for applying the ionic liquid or lubricant composition onto a mechanical device for which lubrication is beneficial, with resulting improvement in friction reduction, wear rate, and/or corrosion inhibition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Materials as additives for advanced lubrication

This invention relates to carbon-based materials as anti-friction and anti-wear additives for advanced lubrication purposes. The materials have various shapes, sizes, and structures and are synthesized by autogenic reactions under extreme conditions of high temperature and pressure. The lubricant compositions comprise carbon-based particles suspended in a liquid hydrocarbon carrier. Optionally, the compositions further comprise a surfactant (e.g., to aid in dispersion of the carbon particles). Specifically, the novel lubricants have the ability to significantly lower friction and wear, which translates into improved fuel economies and longer durability of mechanical devices and engines.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Ionic liquids containing symmetric quaternary phosphonium cations and phosphorus-containing anions, and their use as lubricant additives

An ionic liquid composition having the following generic structural formula: wherein R1, R2, R3, and R4 are equivalent and selected from hydrocarbon groups containing at least three carbon atoms, and X− is a phosphorus-containing anion, particularly an organophosphate, organophosphonate, or organophosphinate anion, or a thio-substituted analog thereof containing hydrocarbon groups with at least three carbon atoms. Also described are lubricant compositions comprising the above ionic liquid and a base oil, wherein the ionic liquid is dissolved in the base oil. Further described are methods for applying the ionic liquid or lubricant composition onto a mechanical device for which lubrication is beneficial, with resulting improvement in friction reduction, wear rate, and/or corrosion inhibition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Metal nanoparticles as lubricant additives

A lubricant composition comprising: (i) silver or gold nanoparticles, each of which is encapsulated by a layer of alkylthiol or alkylamine molecules; (ii) palladium or platinum nanoparticles, each of which is encapsulated by a layer of alkylthiol or alkylamine molecules; and (iii) a fluid in which components (i) and (ii) are present. Further described are methods for applying the lubricant composition onto a mechanical device for which lubrication is beneficial, with resulting improvement in friction and wear reduction and/or corrosion inhibition.

Ihala Gamaralalage, Chanaka Kapila Kumara↗
DOE OSTI2017

Production of Biomass-Based Automotive Lubricants by Reductive Etherification

Growing concern with the effects of CO 2 emissions due to the combustion of petroleum-based transportation fuels has motivated the search for means to increase engine efficiency. The discovery of ethers with low viscosity presents an important opportunity to improve engine efficiency and fuel economy. We show here a strategy for the catalytic synthesis of such ethers by reductive etherification/O-alkylation of alcohols using building blocks that can be sourced from biomass. We find that long-chain branched ethers have several properties that make them superior lubricants to the mineral oil and synthetic base oils used today. These ethers provide a class of potentially renewable alternatives to conventional lubricants produced from petroleum and may contribute to the reduction of greenhouse gases associated with vehicle emissions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Self‐Lubricating Tribo‐Catalytic Activity of 2D High Entropy Alloy Nanoflakes

High Entropy Alloys (HEAs) have garnered attention due to their remarkable tribological attributes. Predominantly, failure mechanisms in HEAs emanate from stress‐induced dislocations, culminating in crack propagation and film delamination. In this study, we report on the synthesis of 2D HEA of (MoWNbTaV) 0.2 S 2 which facilitates shear‐induced energy dissipation at sliding interfaces. The ball‐on‐disk tribological investigations demonstrate unprecedentedly low average coefficients of friction (0.076) and wear rates (10 −9 mm 3 (N∙m) −1 ) under high contact pressures (0.936 GPa) within ambient conditions. Employing multi‐scale characterizations alongside molecular dynamic simulations, we elucidate that the presence of the HEA triggers tribocatalytic activity under high contact pressures emerging as a pivotal factor in extending lubricant lifespan during tribological tests. The resilient lubriciousness coupled with the facile spray coating methodology of (MoWNbTaV) 0.2 S 2 in ambient environments paves the way for the development of a new class of solid lubricants based on 2D HEA.

2D solid lubricant↗
DOE OSTI2016

Tertiary and Quaternary Ammonium-Phosphate Ionic Liquids as Lubricant Additives

In this work we investigated the feasibility of five quaternary (aprotic) and four tertiary (protic) ammonium ionic liquids (ILs) with an identical organophosphate anion as lubricant antiwear additives. Viscosity, oil solubility, thermal stability, and corrosivity of the candidate ILs were characterized and correlated to the molecular structure. The protic group exhibits higher oil solubility than the aprotic group, and longer alkyl chains seem to provide better oil solubility and higher thermal stability. Selected ILs were applied as oil additives in steel-cast iron tribological tests and demonstrated promising anti-scuffing and anti-wear functionality. The thickness, nanostructure, coverage and composition of the tribofilm formed by the besting performing IL were revealed by surface characterization for mechanistic understanding of the tribochemical interactions between the IL and metal surface. Results provide fundamental insights of the correlations among the molecular structure, physiochemical properties and lubricating performance for ammonium-phosphate ILs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Study of Non-Newtonian Behavior of CaO-SiO{sub 2}-Based Mold Slag and Its Effect on Lubrication in Continuous Casting of Steel

To understand the effect of the non-Newtonian behavior of mold slag on lubrication during continuous casting of steel, the current study investigated the rheology of CaO-SiO{sub 2}-based mold slag using a rotational viscometer with variable rotating speed. The constitutive equations at different temperatures were determined. Subsequently, the obtained viscosity as a function of temperature and shear rate was incorporated into a validated mathematical model. The main results demonstrated that slag viscosity decreased dramatically with increased shear rate as the experimental temperature approached the break temperature of mold slag, meaning that the mold slag had a property of shear thinning. The predicted evolution of slag viscosity during mold oscillation was consistent with the shear thinning as the shear rate exerted on the slag channel varied. The calculated slag consumption was higher than that for slag treated as a Newtonian fluid, which agreed well with measurements using a miniature continuous caster. This study finds that the consideration of the non-Newtonian behavior of mold slag is significant to understand the lubrication mechanism and optimize related parameters via simulation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Study of the Mechanism of Liquid Slag Infiltration for Lubrication in Slab Continuous Casting

Consistent and uniform lubrication of the solidifying shell, especially in the meniscus, is crucial for the smooth continuous casting operation and production of strands free of surface defects. Thus, the current study established a coupled model to study the inflow behavior of liquid slag to the mold-strand channel, taking the solidification of steel and slag and the periodic oscillation of mold into account. The difficulties and solutions for the simulation were described in detail. The predicted profiles of the slag rim and initial shell were in good agreement with the reports. The main results indicated that liquid slag could be squeezed out and back into the slag pool in a negative strip period while a large amount of liquid slag could infiltrate into the mold-strand channel. Thus, the amount of slag consumed in the negative strip period was relatively small compared with that in the positive strip period. The predicted variation of slag consumption during mold oscillation was periodic, and the average value was 0.274 kg/m{sup 2}, which agreed well with the slag consumption in industrial practice. The current model can predict and optimize the oscillation parameters aiming at stable lubrication conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Tribological behavior of ceramic-alloy bearing contacts in molten salt lubrication for concentrating solar power

Molten salts are considered as candidate heat transfer fluids and thermal energy storage media for next generation concentrating solar power (CSP). A molten salt circulates inside the piping and heat exchanger and also functions as a lubricant for the sleeve bearings of the CSP pump. Furthermore, wear- and corrosion-resistant high-temperature bearing materials are critical for the pump efficiency and durability. This study evaluated the tribological performance of candidate bearing materials in lubrication of a molten chloride salt mixture (20% NaCl + 40% MgCl 2 + 40% KCl) at 750 °C in an inert argon gas (a simulative CSP pump environment). Six ceramic-alloy pairs were tested, zirconia and silicon nitride against Haynes 244, Hastelloy C276, and Tribaloy T900 alloy, and ranked by the friction coefficient and wear loss. Characterization of worn surfaces suggested the wear mechanism as a combination of abrasion, adhesion, and tribocorrosion. Results from this study provide fundamental insight for the development and selection of bearing materials for molten salt powered CSP pumps.

14 SOLAR ENERGY↗
DOE OSTI2018

A rolling-sliding bench test for investigating rear axle lubrication

An automotive rear axle is composed of a set of hypoid gears, whose contact surfaces experience a complex combination of rolling contact fatigue damage and sliding wear. Full-scale rear axle dynamometer tests are used in the industry for efficiency and durability assessment. Here, this study developed a bench-scale rolling-sliding test protocol by simulating the contact pressure, oil temperature, and lubrication regime experienced in a dynamometer duty cycle test. Initial bench results have demonstrated the ability of generating both rolling contact-induced micropitting and sliding wear and the feasibility of investigating the impact of slide-to-roll ratio, surface roughness, test duration, and oil temperature on the friction behavior, vibration noise, and surface damage. Finally, this bench test will allow studying candidate rear axle lubricants and materials under relevant conditions.

42 ENGINEERING↗
DOE OSTI2019

Ionic liquids as oil additives for lubricating oxygen-diffusion case-hardened titanium

This study attempts to use ionic liquids (ILs) as oil additives to lubricate oxygen-diffusion (OD) case-hardened titanium for improved friction and wear behavior. Four oil-soluble ILs were used as additives in a base oil for boundary lubrication of an OD-treated Ti-6Al-4V surface sliding against a bearing steel ball. The ILs improved the friction behavior to various extents and the two phosphate ILs clearly outperformed the conventional ZDDP. Unlike ZDDP that adversely caused a higher material loss, ILs exhibited excellent wear protection suggesting good material-chemical compatibility. Particularly, the carboxylate IL protected the OD-Ti surface from any measurable wear. As a result, the morphology and chemical composition of the worn surfaces and tribofilms were examined to gain insights of the anti-wear mechanism.

36 MATERIALS SCIENCE↗
DOE OSTI2018

UCST-Type Thermoresponsive Polymers in Synthetic Lubricating Oil Polyalphaolefin (PAO)

Here, this article reports a family of UCST-type thermoresponsive polymers, poly(alkyl methacrylate)s with an appropriate alkyl pendant length, in an industrially important non-volatile organic liquid polyalphaolefin (PAO). The cloud point (CP) can be readily tuned over a wide temperature range by changing the alkyl pendant length; at a concentration of 1 wt% and similar polymer molecular weights, the CP varies linearly with the (average) number of carbon atoms in the alkyl pendant. PAO solutions of ABA triblock copolymers, composed of a PAO-philic middle block and thermoresponsive outer blocks with appropriate block lengths, undergo thermoreversible sol-gel transitions at sufficiently high concentrations. The discovery of thermoresponsive polymers in PAO makes it possible to explore new applications by utilizing PAO’s unique characteristics such as thermal stability, non-volatility, superior lubrication properties, etc. Lastly, two examples are presented: thermoresponsive physical gels for control of optical transmittance and injectable gel lubricants.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Polystyrene Hydrogenolysis to High-Quality Lubricants Using Ni/SiO 2

Pyrolytic and light-activated oxidation processes are leading technologies for utilizing polystyrene (PS) wastes. These approaches exhibit poor selectivities, use complex reactors, and require solvents. Hydrogenolysis is effective for deconstructing polyolefins, but its application to PS feedstocks has been limited. Herein, we demonstrate Ni/SiO 2 catalysts to facilitate PS (M w ≈ 97 kDa) hydrogenolysis to produce lubricant base oils possessing group IV properties, achieving maximum yields of 70% within 6 h at 300 °C and 70 bar of H 2 . Gas, liquid, and oil product yields are stable across reaction conditions, whereas hydrogenation of the PS aromaticity and reduction of the molecular weight benefit from higher temperatures and H 2 pressures. Time-dependent experiments underscore the importance of elevated H 2 pressure, revealing that PS hydrogenolysis occurs sequentially, with aromatic ring hydrogenation preceding degradation of the C–C backbone. Kinetic measurements with 1,2-diphenylethane as a probe molecule demonstrate that ring hydrogenation pis 3 orders of magnitude faster than internal C–C bond cleavage over Ni/SiO 2 . Ni/SiO 2 proves to be effective in the hydrogenolysis of heavier PS polymers and rigid commercial PS products. Conversely, flexibility and foam PS feeds result in Ni/SiO 2 deactivation, attributed to performance additives. Unlike polyolefins, the process produces very little methane and other light hydrocarbons. Furthermore, these findings expand the applicability of hydrogenolysis to PS feedstocks, offering a versatile solution and broadening the range of high-value products from PS to include lubricant base oils.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Marine Toxicity, Biodegradability, and Rolling-Sliding Tribological Performance of Ionic Liquid-Enhanced Environmentally-Acceptable Lubricants for Tidal Turbomachinery

Environmentally acceptable lubricants (EALs) are increasingly being recognized in many fields including waterpower, hydraulics, water transport, agricultural machinery, offshore wind turbines, etc. Specifically, high-performance EALs are demanded for tidal turbomachinery to ensure high efficiency and reliability and avoid the significant risk of direct contamination of the marine ecosystem upon leaks. Here we report a new development of ionic liquid (IL)-enhanced EALs for tidal energy. One short-chain phosphonium phosphate and one short-chain ammonium phosphate ILs were used as the candidate additives and the IL-containing EALs demonstrated significantly improved lubricating performance, much lower toxicity, and increased biodegradability compared with commercial baselines. Specifically, in a rolling-sliding test simulating the operation of a model tidal turbine gearbox bearing, an EAL containing the ILs at a 0.5 wt % concentration demonstrated 40% lower friction, 45% less wear loss, substantially reduced rolling contact fatigue-induced surface damage, and one order of magnitude lower vibration noise compared with a commercial gear oil. In an EPA standard toxicity test, 90 and 70% survival of marine biota was observed when exposed to an EAL containing 5 wt % of the short-chain phosphonium phosphate and ammonium phosphate ILs, respectively, while the selected commercial gear oil and bioderived additive killed all marine biota. In a standard biodegradability test, 2 wt % addition of the phosphonium phosphate IL not only retained the EAL’s ready biodegradability but further boosted the oil decomposition from a range of 60–80% to a higher level of 80–95%. Conversely, adding the commercial bioderived additive downgraded the EAL from readily to inherently biodegradable. Furthermore, this work offers scientific insights for development of ILs as potential EAL additives for marine energy and broader applications.

additives↗