Performance of Powder-Lubricated Journal Bearings With MoS2 Powder: Experimental Study of Thermal Phenomena

Powder-lubricated, quasi-hydrodynamic journal bearings assist in controlling wear and hold promise for integration in outer space systems/mechanisms and in other hostile-environment applications where the use of conventional lubricants is impractical. Described herein are the thermal phenomena and an assessment of the thermal stability, heat generation and dissipation characteristics of slider-type, powder-lubricated bearings. Powder lubricant films provide lift and separate bearing surfaces and cause side leakage. The reduction in friction coefficient and, consequently, in the heat generated in the bearings, drastically reduces wear of the tribomaterials. Further, bearing side leakage carries away most of the heat generated by shear, reducing the heat to the critical bearing surfaces. Also presented are the thermohydrodynamic effects of powder lubrication (MoS2) on bearing performance criteria, e.g., temperature and friction coefficient as a function of speed and load, including the effect of powder flow rate on bearing performance and wear.

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Foil bearings. Guidelines for testing of the performance of foil journal bearings. Testing of load capacity, friction coefficient and lifetime

10.3403/30246943 ◽

2013 ◽

Keyword(s):

Friction Coefficient ◽

Load Capacity ◽

Journal Bearings ◽

Foil Bearings

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Determination of friction coefficient in journal bearings

Materials & Design (1980-2015) ◽

10.1016/j.matdes.2005.09.022 ◽

2007 ◽

Vol 28 (3) ◽

pp. 973-977 ◽

Cited By ~ 36

Author(s):

Bekir Sadık Ünlü ◽

Enver Atik

Keyword(s):

Friction Coefficient ◽

Journal Bearings

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Study of Anisothermal Short Journal Bearings With non-Newtonian Lubricants

Journal of Applied Mechanics ◽

10.1115/1.3627316 ◽

1965 ◽

Vol 32 (4) ◽

pp. 781-787 ◽

Cited By ~ 18

Author(s):

R. I. Tanner

Keyword(s):

Temperature Distribution ◽

Friction Coefficient ◽

Approximate Method ◽

Journal Bearings ◽

Newtonian Fluids ◽

Small Viscosity ◽

Film Viscosity

The equations describing the flow of simple non-Newtonian oils in short journal bearings are solved approximately for low eccentricity ratios and small viscosity variations with temperature. An approximate method for predicting the temperature distribution is compared with available experiments and appears to give realistic results. It is also shown that the reduction in friction coefficient observed by Dubois, Ocvirk, and Wehe in experiments with non-Newtonian fluids cannot be explained by accounting for through-film viscosity variations.

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An Asperity-Based Fractional Coverage Model for Solid Lubricant Film Transfer on a 3D Surface

ASME/STLE 2007 International Joint Tribology Conference, Parts A and B ◽

10.1115/ijtc2007-44489 ◽

2007 ◽

Author(s):

E. Y. A. Wornyoh ◽

C. F. Higgs

Keyword(s):

Friction Coefficient ◽

Control Volume ◽

Lubricant Film ◽

Wear Factor ◽

Fractional Coverage ◽

Disk Interface ◽

Coverage Model ◽

Powder Lubrication ◽

Topography Data ◽

Tribological Parameters

Topography data was obtained from an aluminum thin film deposited unto a substrate. Using this 20 μm × 20 μm specimen, an asperity-based fractional coverage model was used to predict (1) the friction coefficient at a pad/disk interface (2) the thickness of deposited lubricant film and (3) the wear factor for a compacted lubricant pellet in sliding contact. The fractional coverage varies with time and is a useful modeling parameter for quantifying the amount of third body film covering the disk asperities. The model was based on a previous 1-D control volume fractional coverage model which was used to glean tribological parameters including friction coefficient and wear factor. In this model, the wear rate of the pellet, pad friction coefficient, and lubricant thickness can be determined as a function of the pellet load, slider pad load, disk speed, and material properties. Steady-state results from the model adequately predict the self-repairing and self-replenishing nature of powder lubrication as a function of topography.

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Prediction of Wear Rate Dispersion in Mixed Lubrication

World Tribology Congress III, Volume 1 ◽

10.1115/wtc2005-63212 ◽

2005 ◽

Cited By ~ 1

Author(s):

F. Robbe-Valloire ◽

R. Progri ◽

B. Paffoni ◽

R. Gras

Keyword(s):

Friction Coefficient ◽

Wear Rate ◽

Boundary Lubrication ◽

Mixed Lubrication ◽

Tribological Behaviour ◽

Low Friction ◽

Local Boundary ◽

Physico Chemical ◽

Lubricant Films ◽

Second Category

Mixed lubrication is usually related to the partition of contacts, and these latter may be divided into two categories. The first includes all asperities working in thin lubricated film (physico-chemical film) conditions. This situation corresponds to local boundary lubrication and is characterised by a local friction coefficient around 0.1. The second category contains all other asperity types. Due to the existence of a thick lubricant films asperities belonging to the second category exhibit a low friction coefficient. The global tribological behaviour for a given contact, however, is function of both categories, since it involves asperities from both categories.

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Wear of Steam Turbine Journal Bearings at Low Operating Speeds

Journal of Lubrication Technology ◽

10.1115/1.3254599 ◽

1983 ◽

Vol 105 (3) ◽

pp. 313-317 ◽

Cited By ~ 76

Author(s):

K. F. Dufrane ◽

J. W. Kannel ◽

T. H. McCloskey

Keyword(s):

Steam Turbine ◽

Journal Bearings ◽

Optimum Amount ◽

Turbine Generator ◽

Lubricant Films ◽

Low Speeds ◽

Bearing Damage ◽

Geometric Changes

Worn steam turbine bearings were inspected and measured during overhaul periods to determine the extent and nature of the wear. Significant wear was found to exist on turbines using low turning gear speeds (10 rpm or less), and the wear occurred in spite of the presence of lift-pump systems. An analysis of the effect of geometric changes from wear on bearing lubrication at low speeds showed that a limited amount of wear may enhance lubrication. The analysis predicts that an optimum amount of wear exists beyond which the altered geometry would accelerate wear. Considerations were also made of the minimum speeds required to generate lubricant films sufficient to avoid bearing damage by the debris sizes typically found in turbine-generator lubricant systems.

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Mathematical modeling of wear of journal bearings in outer space

Journal of Friction and Wear ◽

10.3103/s1068366608030057 ◽

2008 ◽

Vol 29 (3) ◽

pp. 182-187 ◽

Cited By ~ 1

Author(s):

V. M. Aleksandrov ◽

M. A. Bronovets ◽

I. A. Soldatenkov

Keyword(s):

Mathematical Modeling ◽

Outer Space ◽

Journal Bearings

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An Experimental and Theoretical study of Lubricant flow rate in Static, Grooved, Rectangular Thrust Bearings

Journal of Mechanical Engineering Science ◽

10.1243/jmes_jour_1982_024_006_02 ◽

1982 ◽

Vol 24 (1) ◽

pp. 21-29 ◽

Cited By ~ 2

Author(s):

D. J. Hargreaves ◽

C. M. Taylor

Keyword(s):

Liquid Film ◽

Flow Rate ◽

Theoretical Study ◽

Film Formation ◽

Research Programme ◽

Journal Bearings ◽

Thrust Bearings ◽

Rate Prediction ◽

Lubricant Flow ◽

Lubricant Films

The work to be described here was undertaken in the preliminary stages of a research programme designed to study the true extent of lubricant films in non-stationary, grooved, rectangular thrust bearings. In such externally pressurized bearings an air-lubricant interface may be formed. The study of this interface was seen as a useful step in a consideration of film formation and flow rate prediction in liquid film journal bearings.

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