The Study of the Dynamic Thickness of Organic Boundary Films Under Metallic Sliding Contact

Chua, Wen Hsi; Stachowiak, Gwidon

doi:10.1007/s11249-010-9628-y

Cited by 10 publications

(16 citation statements)

References 25 publications

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“…They use this method to investigate the EHD film formation for values of the lambda parameter between 2 and 3. Recently, Chua and Stachowiak [38] have employed electrical capacitance to evaluate the boundary lubrication phenomena of vegetable oils. They allowed for the contributions of the boundary film (over the real area of contact) the fluid film contained in the valleys between asperities and the out of contact capacitance.…”

Section: Detection Of Asperity Contact In Mixed Regimementioning

confidence: 99%

Electrical Methods for the Evaluation of Lubrication in Elastohydrodynamic Contacts

et al. 2012

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This paper reviews the electrical methods to evaluate lubrication, with the focus on elastohydrodynamic applications. The methods are based on the measurement of the electrical resistance and/or capacitance, and are used to determine the thickness of lubricating films as well as to detect asperity contact in the mixed lubrication regime. The experimental works are introduced in which these methods are used in conventional sliding and rolling/sliding tests and machine component tests including piston ring and cylinder liner, cam and follower, and gears. Also some works on the effect of electric field upon lubrication phenomena are introduced. Advantages and disadvantages of the electrical methods are discussed.

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Section: Detection Of Asperity Contact In Mixed Regimementioning

confidence: 99%

Electrical Methods for the Evaluation of Lubrication in Elastohydrodynamic Contacts

et al. 2012

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“…The materials and test conditions were kept the same as that described in detail earlier in [12]. Briefly, the pure sliding contact was made between a stationary 8 mm diameter ball and a rotating 60 mm diameter disc, both of which are made of 52100 steel.…”

Section: Methodsmentioning

confidence: 99%

“…The apparatus (Figs. 1, 2), described in detail earlier [12], is capable of simultaneously measuring the film thickness and friction of boundary layers subjected to a pure sliding contact between a metallic ball and disc pair. The method of film thickness measurement is based on the method first introduced by Crook [13] and then further developed by Dyson et al [14].…”

Section: Introductionmentioning

confidence: 99%

“…The method of film thickness measurement is based on the method first introduced by Crook [13] and then further developed by Dyson et al [14]. In an earlier pilot study conducted using this technique, the film thickness of refined sunflower oil was observed to grow to 2-3 times its initial thickness, but collapsed after sliding for several hours [12]. In this work, we report the results for three other refined plant oils and nine unrefined plant oils and provide a plausible explanation to these observations.…”

Section: Introductionmentioning

confidence: 99%

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The Growth of Thin Lubricating Films of Plant Oils

Chua

Stachowiak

2010

Tribol Lett

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The extreme conditions of high pressure and shear imposed in a lubricated sliding contact could influence tribochemical reactions that could occur over long sliding distances and time scales, possibly leading to changes in both friction and film thickness. Experiments conducted with 12 plant oils reveal for the first time, that thin lubricating films of some plant oils can grow to thicknesses much greater than what is predicted from either elastohydrodyamic theory or their adsorbed molecular heights. Some films grew as much as 25 times in thickness (unrefined canola oil), while others remained roughly unchanged (flaxseed and olive oil), or grew slightly and then collapsed during the test (safflower oil). The absence of a loss in film thickness and the viscoelastic-like behavior of the film when speeds are reduced to zero, support the view that polymerization could be the main mechanism of film growth. However, the lack of correlation between the degree of unsaturation and the film growth rate suggests that other mechanisms could also be at work.

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“…Thus, the transparent body requirement is a constraint for the optical interferometry and limits its use as essentially a laboratory technique. The studies of thin films and the influence of metallic surfaces on the film chemistry became possible later with the application of precise capacitance measurements using LCR meters with automatic balancing bridges [22]. A unique feature of EHL contacts is that they can provide traction.…”

Section: Lubrication To Combat Frictionmentioning

confidence: 99%

How tribology has been helping us to advance and to survive

Stachowiak

2017

Friction

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Movement between contacting surfaces ranges from macro to micro scales, from the movement of continental plates and glaciers to the locomotion of animals and insects. Surface topographies, lubricant layers, contaminants, operating conditions, and others control it, i.e., this movement depends on the tribological characteristics of a system. Before the industrial revolution, friction and wear were controlled by the application of animal fat or oil. During the industrial revolution, with the introduction of trains and other machinery, the operating conditions at the contacting surfaces changed dramatically. New bearings were designed and built and simple lubrication measures were no longer satisfactory. It became critical to understand the lubrication mechanisms involved. During that period, solid theoretical foundations, leading to the development of new technologies, were laid. The field of tribology had gained a significant prominence, i.e., it became clear that without advancements in tribology the technological progress would be limited. It was no longer necessary to build oversized ship bearings hoping that they would work. The ship or automobile bearings could now be optimized and their behavior predicted. By the middle of the 20th century, lubrication mechanisms in nonconformal contacts, i.e., in gears, rolling contact bearings, cams and tappets, etc., were also finally understood.Today, we face new challenges such as sustainability, climate change and gradual degradation of the environment. Problems of providing enough food, clean water and sufficient energy to the human population to pursue a civilized life still remain largely unsolved. These challenges require new solutions and innovative approaches. As the humanity progresses, tribology continue to make vital contributions in addressing the demands for advanced technological developments, resulting in, for example, reducing the fuel consumption and greenhouse gases emission, increasing machine durability and improving the quality of life through artificial implants, among the others.Keywords: tribology; friction; lubrication and wear Tribology as part of our livesIn our everyday life we take many things for granted. It never occurs to us to pause and think why our hands or feet provide a perfect grip on most of the surfaces. We rarely think why sharks swim so fast or why geckos can walk on glass surface even when upside down. We expect spacecraft or satellites that we send to explore our solar system and beyond to operate smoothly even after many months or years of being idle. We expect that our trains and aircraft would stop exactly at the designated places at train stations and airports. When hopping into a car we don't think twice about the material used for the car seats. We don't think often why the tectonic plates or glaciers move with apparent ease. These seemingly diverse problems, and many others, are of great interest and research focus of tribologists. Tribology has helped us to discover not only the underlying mechanisms involved...

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The Study of the Dynamic Thickness of Organic Boundary Films Under Metallic Sliding Contact

Cited by 10 publications

References 25 publications

Electrical Methods for the Evaluation of Lubrication in Elastohydrodynamic Contacts

Electrical Methods for the Evaluation of Lubrication in Elastohydrodynamic Contacts

The Growth of Thin Lubricating Films of Plant Oils

How tribology has been helping us to advance and to survive

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