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7 papers found.
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Effect of Base Oil Structure on Elastohydrodynamic Friction

The EHD friction properties of a wide range of base fluids have been measured and compared in mixed sliding–rolling conditions at three temperatures and two pressures. The use of tungsten carbide ball and disc specimens enabled high mean contact pressures of 1.5 and 2.0 GPa to be obtained, comparable to those present in many rolling bearings. The measurements confirm the importance ...

On the Mechanism of ZDDP Antiwear Film Formation

Zinc dialkyldithiophosphate additives are used to control wear and inhibit oxidation in almost all engine oils as well as many other types of lubricant. They limit wear primarily by forming a thick, protective, phosphate glass-based tribofilm on rubbing surfaces. This film formation can occur at low temperatures and is relatively indifferent to the chemical nature of the substrate. ...

The Relationship Between Friction and Film Thickness in EHD Point Contacts in the Presence of Longitudinal Roughness

This study investigates friction and film thickness in elastohydrodynamic contacts of machined, rough surfaces, where roughness is dominated by longitudinal ridges parallel to the rolling/sliding direction. A ball-on-disc tribometer was used to simultaneously measure friction and film thickness in rough contacts as well as with nominally smooth specimens for comparison. The studied ...

On the Commonality Between Theoretical Models for Fluid and Solid Friction, Wear and Tribochemistry

, University of Wisconsin-Milwaukee , Milwaukee, WI 53211 , USA 1 Tribology Section, Department of Mechanical Engineering, Imperial College , London SW7 2AZ , UK 2 & Hugh Spikes Tribology is concerned with the

A Study of the Lubrication of EHL Point Contact in the Presence of Longitudinal Roughness

This work investigates the effect on elastohydrodynamic lubrication of roughness ridges oriented along the rolling–sliding direction, such as may be present on rolling bearing raceways. The roughness of the three specimens tested is characterised by the RMS of surface heights and a dominant wavelength. Optical interferometry and a ball-on-disc set-up were employed to map the oil ...

Confining Liquids on Silicon Surfaces to Lubricate MEMS

Liquid lubrication may provide a solution to the problem of high friction and wear in micro-electro-mechanical systems. Although the effectiveness of this approach has been demonstrated in laboratory-based friction tests, practical constraints prevent it from being applied in commercial devices. The main problem is how to position the lubricant on a silicon surface in order to ...