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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society of Tribologists and Lubrication Engineers
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Journal DOI :
The Korean Society of Tribologists and Lubrication Engineers
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Volume & Issues
Volume 25, Issue 6 - Dec 2009
Volume 25, Issue 5 - Oct 2009
Volume 25, Issue 4 - Aug 2009
Volume 25, Issue 3 - Jun 2009
Volume 25, Issue 2 - Apr 2009
Volume 25, Issue 1 - Feb 2009
Selecting the target year
Effects of Temperature on the Tribological Characteristics of Thermoplastic Polymer Film
Kim, Kwang-Seop ; Heo, Jung-Chul ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 207~216
Friction tests were carried out in order to investigate the effects of temperature on the friction and wear behaviors between a PMMA film and a fused silica lens using a microtribometer. The friction forces on the PMMA film were measured under atmospheric condition as the temperature of the film was increased from 300 K to 443 K. The contact area between the film and the lens was observed. The tribological characteristics of the film were significantly changed as the temperature increased. The changes were discussed with the change of the film state from glassy to viscous flow. In addition, the results showed that the friction behavior can be varied with the thermal history of the PMMA film. Residual solvent in the PMMA film could emerge to the PMMA surface due to an additional heating and the solvent on the film surface decreased the friction force.
A Study on Friction Behavior of Textured Surface in Unlubricated State
Oh, Seok-Ju ; Kim, Sung-Gi ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 217~224
In this study, friction tests were carried out in order to investigate the friction behavior of textured surface in unlubricated state using ball-on-disk type apparatus. Test specimens were SUJ2 bearing steel ball and SM45C steel disk. Square arrays of circular micro-dimples were created on the surface of disk specimen by Nd:YAG Laser. Friction tests were performed for the disk specimen with various micro-dimple parameters and was also conducted for the variation of normal loads and relative velocities. The results showed that fiction coefficient of textured surface was lower than that of non-textured surface and the deeper depth of micro-dimple was, the lower friction coefficient obtained at the same diameter of micro-dimple in unlubricated state. Area density of micro-dimple had an effect on the friction coefficient. It was also found that friction coefficient generally decreased with the increase of normal load and relative velocity.
Contact Analysis Between Rubber Seal, a Spherical Particle and Coated Steel Surface
Park, Tae-Jo ; Jo, Hyeon-Dong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 225~230
Seals are very useful machine components in protection of leakage of lubricant or working fluid, and incoming of debris from outside. Various elastomer are widely used as sealing materials and the shaft surfaces are generally coated with high hardness material after heat treatment. It is generally known that the foreign debris and wear particles get stuck into sealing surface, the steel shaft surface can be damaged and worn by mainly abrasive wear. In this paper, using MARC, contact analysis are conducted to show the hard coated steel shaft surface can be fatigue failed by very small elastic particle intervened between seal and steel surface. Variations of contact and von-Mises stress distributions and contact half-widths with interference and coating thickness are presented. The maximum von-Mises stress occurs always in the coating layer or between coated layer/substrate interface. Therefore the coated sealing surface can be fatigued and then failed by very small particles. The results can be used in design of sealing surface and further studies are required.
Effect of Contact Pressure on the Variations in Coefficients of Friction Between Porcine Knee Joint Cartilage and Co-Cr Alloy in a Repeat Pass Sliding Motion
Lee, Kwon-Yong ; Kim, Hwan ; Lee, Young-Ze ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 231~235
In this study, the influence of contact pressure on the variation in coefficients of friction between porcine knee joint cartilage and Co-Cr alloy in a repeat pass sliding motion was investigated. Flat-ended cartilage pin specimens(9 mm diameter, 8 mm long) were prepared from porcine(6 months old) knee joints by a drill-type punch. Friction tests were conducted by using a pin-on-disk type friction tester for an hour in PBS lubricated condition under the contact pressures of 0.5, 1 and 2 MPa with 50 mm distance per a cycle at ambient condition. As a result, coefficients of friction increased as the test duration increased for all contact pressures. The maximum coefficients of friction were 0.082, 0.06 and 0.098 for 0.5, 1, and 2 MPa, respectively. It showed that coefficients of friction of porcine knee joint cartilage against Co-Cr alloy depended on the level of contact pressure and related to squeeze film lubrication mechanism.
Acoustic Viscosity Characteristics of Oils with High Molecular Weight VI Improver Additives
Kong, H. ; Ossia, C.V. ; Han, H.G. ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 236~242
Oil viscosity is one of the important parameters for machinery condition monitoring. Basically, it is expressed as kinematic viscosity measured by capillary flow and dynamic or absolute viscosity measured by rotary shear viscometry. Recently, acoustic wave techniques appear in the market, measuring viscosity as the product of dynamic viscosity and density. For Newtonian fluids, knowledge of density allows conversion from one viscosity parameter to the other at a specific shear rate and temperature. In this work, oil samples with different chain lengths of viscosity index (VI) improvers and concentrations were examined by different viscometric techniques. Results showed that acoustic viscosity measurements give misleading results for oil samples with high molecular weight VI improvers and at low temperatures
Friction Characteristics of Magnetic Clutch Used in Automobiles
Kim, Dong-Wook ; Kim, Kyung-Woong ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 243~249
A magnetic clutch consists of pulley and disk. It delivers and isolates the power needed for the operation of the compressor used in automotive air conditioning system. To improve the performance, efficiency and durability of automotive air conditioning system, appropriate design of pulley, disk and system working parameters(the magnitude of magnetic force, and so on) is necessary. For that goal, it is required to understand the friction characteristics of magnetic clutch for the initial operating time. In this study, friction tests were carried out in order to investigate the effect of sliding velocity on the friction characteristics of magnetic clutch using pin-on-disk type friction and wear tester. For experiments, pulley and disk used in real automotive air conditioning system were considered. Friction experiments were conducted under various sliding velocities, and coefficients of kinetic friction were obtained. Under the experimental conditions considered in this study, the coefficients of kinetic friction increased with the increase of test number(sliding distance) and decreased with the increase of sliding velocity.
Oxidation and Fretting Wear Characteristics of Zirconium Alloy Tubes
Chung, Il-Sup ; Lee, Ho-Seong ; Lee, Myung-Ho ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 250~255
Oxidation characteristics of Zirlo and Zircaloy-4 tubes, which are widely used as nuclear power fuel cladding, are studied in steam environment up to
. Oxidation resistances are compared in terms of the mass increase due to the absorption of oxygen. The evolution of microscopic structure accompanied with the oxidation process is investigated. Also, the influence of oxidation on the fretting wear characteristics of the tubes is studied. Piezo-electrically actuated rig is employed to fret the tubes with cross-contacting arrangement. Wear scar is observed and measured, by using microscopes and a 3D-profiler. The results of fretting wear are quantified in terms of scar size, wear volume and wear coefficient, and compared for the three different tube materials of oxidated Zirlo, virgin Zirlo and Zircaloy-4.
A Study on Estimating of Fretting Wear of a Spline Coupling
Kim, Eung-Jin ; Lee, Sang-Don ; Cho, Yong-Joo ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 256~260
Fretting is a kind of wear which effects on reliability and durability. When machine parts are joined joint in parts such as a bolt or a rivet or a pin, fretting phenomenon is occurred by micro relative movement. When fretting occurs in joint parts, there is wear which is the cause of fatigue crack. Recently, although the ways of assessment of fatigue and damage tolerance are established, there is no way to evaluate fatigue crack initiation life by fretting phenomenon. Consequently, the prediction of life and prevention plan caused by fretting are needed to improve reliability. The objective of this paper is to predict fretting wear by using a experimental method and contact analysis considering wear process. For prediction of fretting wear volume, systematic and controlled experiments with a disc-plate contact under gross slip fretting conditions were carried out. A modified Archard equation is used to calculate wear depths from the contact pressure and stroke using wear coefficients obtained from the disc-plate fretting tests.
Wear Characteristics of Rubber-Seal for Inflow of Dust Particles in Automobile Chassis System -PART II: The Influence of Dust Particle Inflow on Wear Characteristics of Rubber-Seal-
Lee, Young-Ze ; Chung, Soon-Oh ; Won, Tae-Yeong ; Kim, Gi-Hoon ; Kim, Dae-Sung ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 261~264
Environmental factors affect parts of the automobile. When dust particles are embedded, specially, friction and wear of the rubber-seal in automobile chassis system are increased. Increase in friction and wear leads to weakness of component and reduction of mechanical life. In this study, the wear characteristics of rubber-seal for inflow of dust particles are investigated. Silica(
) and alumina(
) particles are used as a dust particle because these particles are main elements of dust particles. The sliding wear tester are used for investigate the wear characteristics of rubber-seal. If the single dust particle(
) is embedded in the rubber-seal component, the influence of dust particle size is more than that of inflow rate on the wear characteristics of rubber-seal. If the mixed dust particles are embedded in the rubber-seal component, the wear rate is increased as the rate of alumina that has a bigger hardness is increased. If the mixed dust particles that have different hardness are embedded in the rubber-seal component, the influence of particle size is more than that of particle hardness.
A Study on the Friction Characteristics of Tappet by Low Friction Coating
Seo, Joon-Ho ; Lim, Dae-Soon ; Na, Byung-Chul ;
Journal of the Korean Society of Tribologists and Lubrication Engineers, volume 25, issue 4, 2009, Pages 265~269
The wear of the contact in the tappet accounts for the greatest portion of entire friction loss of an engine, leading to the occurrence of abnormal wear. The coated specimens for earn-tappet wear test were producted by using PVD-Sputtering coating method. It examined the friction characteristics occurring between the earn and the tappet by using the dedicated wear tester and found that the friction torque value was reduced through comparison testing with the existing part when the low friction coating was applied. So application of the low friction coating to actual vehicles will reduce the fuel economy and occurrence of noise-vibration.