A novel surface texture for magnetic fluid lubrication

2011

Lubrication Science

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115

The appealing and enigmatic properties of biological surfaces inspire people that a smooth surface is not always the best. Currently, the patterns of microdimples have attracted more attentions since such closed texture cells are supposed to generate hydrodynamic pressure easily. The advanced manufacturing techniques provide precision and freedom for the fabrication of microdimples, which enables the optimisation of dimple geometry and distribution to obtain better tribological performances. Over the past decade, experiments were carried out to investigate the effects of microdimples on various materials under different operating conditions. Analytical models were established to evaluate the hydrodynamic effect of the dimple patterns. The results suggest that the design of dimple pattern following hydrodynamic principle would obtain good tribological performance under high‐speed low‐load conditions; however, for the case of low‐speed high‐load conditions, shallow and small dimples would have more obvious friction reduction effect than those designed based on hydrodynamic pressure generation. Copyright © 2011 John Wiley & Sons, Ltd.

Section: Advanced Surface Texture Designmentioning

confidence: 79%

Dimple patterns design for different circumstances

2011

Lubrication Science

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115

“…The fabrication process mainly consists of three steps: photolithographic, electrolytical machining and electrodeposition. The specific fabrication process can be found in Shen et al 11 Figure 2(a) gives a square arrayed dimple pattern after electrolytic etching and Figure 2(b) presents the 3D image of one dimple. The area density of the dimples on the surface is 10% with a diameter of 300 mm.…”

Section: Experimental Methodsmentioning

confidence: 99%

Study on the frictional properties of micro-magnet arrayed surface lubricated with ferrofluids

Proceedings of the Institution of Mechanical Engineers, Part J:

2012

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Ferrofluids (FF) are stable colloids exhibiting normal liquid behavior coupled with magnetic properties. As a kind of lubricant, the most obvious advantage is that FF can be maintained in the desired position without any leakage by applying a permanent magnet. For the above characteristics, a kind of micro-magnet arrayed surface for FF lubrication was introduced in this article. The tribological performances of the surface were tested under plane contact conditions using FF as a lubricant. Flat SUS316 steel and polytetrafluoroethylene (PTFE) were used as opposite pairs, respectively, for their different wetting properties with FF. The experimental results show that compared with normal surface/PTFE frictional pair, the magnetic surface/PTFE couple expresses distinct friction increasing, while the magnetic surface/SUS316 steel pair presents obvious advantages of antifriction especially at high sliding speeds. The higher the surface magnetic flux is, the better is the tribological performance it displays especially at a higher sliding speed.

“…To reduce the size of the bulk magnet, a novel magnetic surface was designed for FFs lubrication. 90,91 Micro dimple patterns were first fabricated on a disk surface and the permanent magnet films then were electrodeposited into these dimples. Figure 16 shows the magnetic surfaces before and after covered with FFs.…”

Section: Bearing Lubrication Testsmentioning

confidence: 99%

“…97 The main advantages of these bearings over conventional bearings were introduced, such as extremely low nonrepetitive run-out, good damping and quietness of operation, maintenance free service and high reliability. 90 Urreta et al 98 set up a test bench for plain journal bearings lubricated with FFs and magnetorheological fluids (MR). Theoretical analysis was carried out with numerical solutions of Reynolds equation, based on apparent viscosity modulation for FFs and Bingham model for MR.…”

Section: Bearing Lubrication Testsmentioning

confidence: 99%

Ferrofluids lubrication: a status report

Huang

2015

Lubrication Science

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Ferrofluids (FFs) are stable colloidal suspensions composed of single‐domain magnetic nanoparticles dispersed in a carrier liquid. And it is an intelligent material, exhibiting normal liquid behaviour coupled with superparamagnetic properties. Since the properties and the location of these fluids can easily be influenced by a magnetic field, FFs have recently attracted many scientific, industrial and commercial applications. Lubrication is one of the most important applications for FFs, and the advantage of FFs as lubricant, over the conventional ones, is that the former can be retained at the desired location with moderate magnetic fields. The main focus of this paper is to present a comprehensive review on FFs lubrication theories based on the three flow models of Neuringer–Rosensweig, Shliomis and Jenkins. Besides, a few experimental studies on FFs lubrication are discussed briefly. Copyright © 2015 John Wiley & Sons, Ltd.