Correlation Between Film Forming Ability and Rheological Properties of New and Aged Lowsaps Automotive Lubricants

The rheological behavior of fresh and aged diesel LowSaps 5W30 lubricant, is studied with both ElastoHydroDynamic tribometer, and low shear and high shear viscometers. The evolution of the film thickness in EHD contact, that varies between 1nm and 150 nm, displays two types of lubrication process according to rolling speed. On the one hand, a classical EHD behaviour, controlled by viscosity, may be observed beyond 35 nm with a significant shear thinning effect in the range of temperatures. On the other hand, below 35nm, a steep drop of film thickness indicates the unability of the viscosity improver polymer to form a thin film within the contact. These observations are closely related to rheological measurements carried out in a shear rate range from 10s−1 to 107s−1, and temperatures between 25°C and 150°C. Indeed, analysis of two rheological parameters, polymer relaxation time and hydrodynamic radius, may explain non newtonian and thin film effects in the EHD experiments. A rheological modelling based on the Cross model is developed to calculate these parameters. Then, the principle of time-temperature equivalence is used to map the characteristics of lubricants. Finally, the approach coupling EHD tribometer\Viscometer is applied to lubricants which have been degraded during a light duty diesel engine test.

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The behaviour of lubricants in elastohydrodynamic contacts

Proceedings of the Institution of Mechanical Engineers Part J Journal of Engineering Tribology ◽

10.1243/1350650971542345 ◽

1997 ◽

Vol 211 (2) ◽

pp. 91-106 ◽

Cited By ~ 24

Author(s):

A. J. Moore

Keyword(s):

Thin Film ◽

Physical Explanation ◽

Ehd Lubrication ◽

Film Forming ◽

Theoretical Investigations ◽

Research Findings ◽

Rheological Modelling ◽

Similarities And Differences ◽

Forming Behaviour ◽

Made In

Difficulties once found in accounting for the tractional behaviour of lubricants in elastohydrodynamic (EHD) contacts have largely been resolved. A wealth of research stimulated by this problem has gradually unravelled the underlying rheological complexities and laid the basis for a coherent physical explanation. The understanding achieved and the problems that remain are briefly reviewed. Despite the advances made in rheological modelling, developments are not readily taken up by those engaged in theoretical investigations. Although computational complexity must inevitably rise when lubricants are modelled realistically, the penalty for not doing so must be clearly understood. The implications can be readily devined from previous research findings. Progress made in the exploration of EHD film thickness is also examined. Similarities and differences in film-forming behaviour in thick film (> 0.1 μm) and thin film (< 0.1 μm) regimes are identified and consideration given to the interpretational difficulties that may arise as EHD and boundary regimes begin to merge. Finally, a few observations are made on the value of EHD lubrication studies to automotive engineering.

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The Viscosity of Polyalphaolefins Mixtures at High Pressure and Stress

Journal of Tribology ◽

10.1115/1.4041124 ◽

2018 ◽

Vol 141 (2) ◽

Cited By ~ 2

Author(s):

Scott Bair ◽

Samuel Flores-Torres

Keyword(s):

High Pressure ◽

Shear Stress ◽

Film Thickness ◽

Shear Viscosity ◽

Mixing Rule ◽

Base Oils ◽

Film Forming ◽

Low Shear Viscosity ◽

Temperature And Pressure ◽

Low Shear

Understanding the pressure and shear dependence of viscosity is essential to an understanding of the mechanisms of film forming and friction in concentrated contacts. The blending of different molecular mass polyalphaolefins (PAOs) may permit the formulator to arrive at a desired combination of film thickness and friction. The viscosities of PAO base oils and their blends were measured versus temperature, pressure, and shear stress to 1 GPa in pressure. The Grunberg–Nissan mixing rule, with effective mole fractions, provides an excellent mixing rule for the temperature and pressure-dependent low-shear viscosity. This work provides the first look at a possible mixing rule for the non-Newtonian response of mixtures of base oils.

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Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100061847 ◽

1967 ◽

Vol 25 ◽

pp. 366-367

Author(s):

D. M. Davies ◽

R. Kemner ◽

E. F. Fullam

Keyword(s):

Thin Film ◽

Electron Microscope ◽

High Altitude ◽

Amyl Acetate ◽

Temperature Variations ◽

Film Forming ◽

Film Specimen ◽

Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

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Numerical Analysis of the Effect of Thin-Film Thickness and Material in Field Mapping of Eddy-Current Probes Using Photoinductive Technique

IEICE Transactions on Electronics ◽

10.1587/transele.e95.c.86 ◽

2012 ◽

Vol E95-C (1) ◽

pp. 86-92

Author(s):

Yen-Lin PAN ◽

Cheng-Chi TAI ◽

Dong-Shong LIANG

Keyword(s):

Thin Film ◽

Numerical Analysis ◽

Film Thickness ◽

Eddy Current ◽

Thin Film Thickness ◽

Field Mapping

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Correlation between electrical and rheological measurements on sewage sludge

Water Practice & Technology ◽

10.2166/wpt.2007.002 ◽

2007 ◽

Vol 2 (1) ◽

Author(s):

E. Dieudé-Fauvel ◽

J.-C. Baudez ◽

P. Coussot ◽

H. Van Damme

Keyword(s):

Sewage Sludge ◽

Rheological Parameters ◽

Clear Correlation ◽

Electrical Measurements ◽

Rheological Measurements ◽

Sludge Characterization ◽

Relaxation Experiments ◽

Rheological Experiments ◽

The One ◽

Microstructure Of The Material

In order to improve sewage sludge characterization for both dewatering and agricultural spreading, we have studied their electrical and rheological properties. On the one hand, electrical measurements give a picture of the microstructure of the material (charges, particles mobility), whereas on the other hand, rheological experiments describe its macrostructure (consistency). The interactions of the matter are the link between them. Our results showed that sludge becomes more conductive when its dry content (for a defined composition) or the temperature increases, and also during aging. In parallel its apparent viscosity increases with the dry content but decreases with the temperature or during aging. In each case a clear correlation was found between electrical and rheological parameters. This relationship clearly depends on sludge composition, and also on parameters such as the temperature, the observation frequency, the velocity range in the case of relaxation experiments. Finally, those types of experiments can be correlated to improve the comprehension of sludge structure and consistency characterization.

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Organic thin film thickness-dependent photocurrents polarity in graphene heterojunction phototransistor

Carbon ◽

10.1016/j.carbon.2021.03.024 ◽

2021 ◽

Vol 178 ◽

pp. 506-514

Author(s):

Meiyu He ◽

Jiayue Han ◽

Xingwei Han ◽

Jun Gou ◽

Ming Yang ◽

...

Keyword(s):

Thin Film ◽

Film Thickness ◽

Organic Thin Film ◽

Thin Film Thickness

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Experimental Study on the Thickness-Dependent Hardness of SiO2 Thin Films Using Nanoindentation

Coatings ◽

10.3390/coatings11010023 ◽

2020 ◽

Vol 11 (1) ◽

pp. 23

Author(s):

Weiguang Zhang ◽

Jijun Li ◽

Yongming Xing ◽

Xiaomeng Nie ◽

Fengchao Lang ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Grain Size ◽

Integrated Circuits ◽

Film Thickness ◽

Depth Range ◽

Micro Electro Mechanical Systems ◽

Si Substrates ◽

Sio2 Thin Film ◽

Average Grain Size

SiO2 thin films are widely used in micro-electro-mechanical systems, integrated circuits and optical thin film devices. Tremendous efforts have been devoted to studying the preparation technology and optical properties of SiO2 thin films, but little attention has been paid to their mechanical properties. Herein, the surface morphology of the 500-nm-thick, 1000-nm-thick and 2000-nm-thick SiO2 thin films on the Si substrates was observed by atomic force microscopy. The hardnesses of the three SiO2 thin films with different thicknesses were investigated by nanoindentation technique, and the dependence of the hardness of the SiO2 thin film with its thickness was analyzed. The results showed that the average grain size of SiO2 thin film increased with increasing film thickness. For the three SiO2 thin films with different thicknesses, the same relative penetration depth range of ~0.4–0.5 existed, above which the intrinsic hardness without substrate influence can be determined. The average intrinsic hardness of the SiO2 thin film decreased with the increasing film thickness and average grain size, which showed the similar trend with the Hall-Petch type relationship.

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Precise control of Jeff=12 magnetic properties in Sr2IrO4 epitaxial thin films by variation of strain and thin film thickness

Physical Review B ◽

10.1103/physrevb.102.214402 ◽

2020 ◽

Vol 102 (21) ◽

Author(s):

Stephan Geprägs ◽

Björn Erik Skovdal ◽

Monika Scheufele ◽

Matthias Opel ◽

Didier Wermeille ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Magnetic Properties ◽

Film Thickness ◽

Epitaxial Thin Films ◽

Thin Film Thickness ◽

Precise Control

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Optimization of Fiber Bragg Gratings Inscribed in Thin Films Deposited on D-Shaped Optical Fibers

Sensors ◽

10.3390/s21124056 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4056

Author(s):

José Javier Imas ◽

Carlos R. Zamarreño ◽

Ignacio del Villar ◽

Ignacio R. Matías

Keyword(s):

Thin Film ◽

Film Thickness ◽

Optical Fibers ◽

Flat Surface ◽

Sno2 Thin Film ◽

Thin Film Thickness ◽

A Value ◽

Surrounding Refractive Index ◽

Reflected Power ◽

Fabrication Parameters

A fiber Bragg grating patterned on a SnO2 thin film deposited on the flat surface of a D-shaped polished optical fiber is studied in this work. The fabrication parameters of this structure were optimized to achieve a trade-off among reflected power, full width half maximum (FWHM), sensitivity to the surrounding refractive index (SRI), and figure of merit (FOM). In the first place, the influence of the thin film thickness, the cladding thickness between the core and the flat surface of the D-shaped fiber (neck), and the length of the D-shaped zone over the reflected power and the FWHM were assessed. Reflected peak powers in the range from −2 dB to −10 dB can be easily achieved with FWHM below 100 pm. In the second place, the sensitivity to the SRI, the FWHM, and the FOM were analyzed for variations of the SRI in the 1.33–1.4 range, the neck, and the thin-film thickness. The best sensitivities theoretically achieved for this device are next to 40 nm/RIU, while the best FOM has a value of 114 RIU−1.

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