• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.06a
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• pp.203-208
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• 1999

Friction and wear test have been performed on nylon, polyacetal, and PTFE(polytetrafluoroethylene), in reciprocating dry sliding conditions against a steel disc. According to the results, polyacetal show lowest wear rates and PTFE was found to exhibit lowest friction coefficient. The prominent wear mechanism found were adhesion and abrasion.

• Tribology and Lubricants
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• v.16 no.1
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• pp.33-38
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• 2000

Abstract- In this paper tribological characteristics of solid and liquid phase sintered W/C-35%Ni tappets were investigated. Three test methods were performed to investigate the wear and surface damage mechanism of sintered tappets. First, block-on-ring wear test was performed to investigate the wear characteristics under pure sliding condition. Second, simplified cam and tappet tests (called component wear test hereafter) were carried out to simulate the real contact history of cam and tappet. Also, after the test, contact surfaces were analyzed with scanning electron microscope to study the wear mechanism. As a final screening, engine dynamo tests were performed. Results showed that in the block on ring sliding wear test, solid phase sintered specimens showed superior wear resistance to liquid phase sintered specimens. The component wear tests and engine dynamo tests also showed the same results. Therefore, in these tests, solid phase sintered tappet material revealed superior wear resistant properties to liquid phase sintered one.

• Tribology and Lubricants
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• v.19 no.4
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• pp.211-216
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• 2003

This paper was studied on the corrosion and corrosion-wear behavior of chromium (Cr) plating in the acidic environments. In the various pH of acidic solutions, the electrochemical polarization test and wear-corrosion test of Cr plating were carried out. And thus potential, corrosion current density and corrosion-wear loss behaviour of Cr plating are investigated.

• Tribology and Lubricants
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• v.17 no.1
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• pp.40-55
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• 2001

Acoustic emission(AE) signal has been widely utilized to monitor the interaction at the head/disk interface. In this work the relationship between the AE signal and the state of contact between the slider and the disk is presented. Results of the FFT(Fast Fourier Transform) analyses of the AE signal could be used to better understand the interfacial interaction. Also, it was found that wear particles affect the AE signal. Therefore, the signal can be used to monitor the wear particle presence at the interface.

• Tribology and Lubricants
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• v.11 no.5
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• pp.184-189
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• 1995

The antiwear performance of dialkyl 3, 5-di-t-butyl 4-hydroxy benzyl phosphonates was investigated using a four ball wear test machine. Diethyl 3, 5-di-t-butyl 4-hydroxy benzyl phosphonate (DEP) and dibutyl 3,5-di-t-butyl 4-hydroxy benzyl phosponate (DBP) among them showed excellent antiwear performances compared with conventional additives, ZDDP and TCP as the bulk oil temperature and the sliding velocity increased. The surface analysis through an optical microscopy was conducted for tribological studies.

• Tribology and Lubricants
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• v.5 no.2
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• pp.101-106
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• 1989

Various squeeze film dampers have been theoretically and experimentally studied for flexible rotors. A cylindrical bush damper among them was selected and applied in a test rotor supported with ball bearings. A quiet running of the rotor over a critical speed was observed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.04a
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• pp.232-241
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• 1997

The tribological behavior for MoS$_2$ bonded films is evaluated according to the international standard testing methods, such as ASTM D 2625(Falex tester) and ASTM D 2714(LFW-1 tester). It has been well known that the tribological behavior for MoS$_2$ bonded films is affected by several factors. However, in this work, the wear life for MoS$_2$ bonded films is mainly experimentally measured with different contact geometry, and evaluated in terms of the frictional heating according to the contact geometry of tribotester. The test results show that the wear life of MoS$_2$ bonded films is significantly affected not only by the frictional heating, but also by the contact pressure, test running-in conditions, and the contact conformity.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.66-75
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• 1997

This study was undertaken to investigate tribology characteristics of the alumina ceramics($Al_2O_3$) of the various purity for the variation of ambient condition such as air and vacuum. The wear test was carried out under different experimental condition using the wear test device, which was designed for this study, and in which the annular surface of wear testing specimens as well as mate specimen made of STB2 steel, were subjected to sliding speed, applied load and the sliding distance. The results obtained were as follows. As the ambient pressure decreases, the friction coefficient increases because the protective layer made of absorption due to decrease of the amount of ambient gas can not be formed. As the friction coefficient paticularly for 85% alumina lower than 95% and 99.7% in the alumina purity increases by an influence of heat accumulation caused by small elastic modulus and thermal conductivity. The friction surface of ceramics can be protected in the air by the influence of the oxides transfered from STB2. However, in the vacuum, the protective layer made of the absorption substance can not be formed due to the decrease of ambient gas.

• Tribology and Lubricants
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• v.20 no.6
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• pp.343-349
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• 2004

The adsorption of soot particles onto a sensor surface of the engine soot detector posses a critical problem in the measurement. In order to prevent the optical rod surface from soot contamination, various functional coatings and flow-induced cleaning were applied to the surface in this work. For surface coatings, various materials of self-assembled monolayers (SAM) such as OTS (octadecyltrichlorosilane), PFDTES (perfluorodecyl-triethoxysilane) and PFDTMS (perfluorodecyltrimethoxysilane) were coated on the optical rod surface ,which have different characteristics in both hydrophobicity and oleophobicity. These coatings were tested with soot content varying from $0\%\;to\;3wt\%$ and oil temperature from 20 to $70^{\circ}C$. Test results showed that surface coatings were not effective for preventing the adsorption of soot panicles on the surface of optical rod. It was thought that these coatings provided the surface with additional attractive surface forces. However, it was found that adsorption of soot particles onto a sensor surface was minimized by flow-induced cleaning. This effect was tested with varying the flow velocity.

• Tribology and Lubricants
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• v.18 no.1
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• pp.1-8
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• 2002

Nano adhesion and friction between a $Si_{3}N_{4}$ AFM(atomic force microscope) tip and thin silver films were experimentally studied. Tests were performed to measure the nano adhesion and friction in both AFM and LFM(lateral force microscope) modes in various range of normal loads. Thin silver films deposited by IBAD (ion beam assisted deposition) on Si-wafer (100) and other Si-wafers of different surface roughness were used. Results showed that nano adhesion and friction decreased with the surface roughness. When the Si surfaces were coated by pure silver, the adhesion and friction decreased. But the adhesion and friction were not affected by the thickness of IBAD silver coating. As the normal force increased, the adhesion forces of bare Si-wafer and IBAD silver coating film remained constant, but the friction forces increased linearly. Test results suggested that the friction was mainly governed by the adhesion as long as the load was low.