• Tribology and Lubricants
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• v.10 no.4
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• pp.59-68
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• 1994

This study is concerned with the change of physical and chemical properties of the used oil in gasoline and LPG engine. The used oils of engine were sampled from dynamometer and cars. The field tests of car were done in city and on highway. The properties of oil were TAN, TBN, visocity, oxidation, ZDTP depletion factor and etc. Also the relation between the chemical change and antiwear property was studied. From the study, it was shown that the decrease of antiwear property of used oil was depended on the changes of ZDTP depletion factor as well as TAN (total acid number). Also, it was found that the oil used by LPG car was deteriorated within the shortest distance among the other gasoline cars. The antiwear property of oil decreased as the running distance increased. The gasoline engine oil drove mainly on highway was the least deteriorate of properities for the same running distance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.341-342
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• 2002

Although vegetable oils provide good lubricity, they still need optimization by certain additive technology for practical applications. ZDTP improve antiwear properties of vegetable oils. However the additive performance depends on quality of the base Oil. Antioxidants were applied to prevent the auto-oxidation of vegetable oils. Good synergistic effect of anti-wear and antioxidant additives was confirmed.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.152-160
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• 1997

A diesel engine oil which was formulated and a commercial diesel engine oil (API CG4) made from same base oil were tested by car and analyzed of their physical, chemical and mechanical properties. The tested oil to be analyzed were sampled from engine every 1000 km until 8000 km and determined the kinematic viscosity, TAN, TBN, metal content in oil, additive depletion, antiwear property and IR analysis. From the study, both the tested oils were almost same properties for the change of TAN and TBN, but the change of kinematic viscosity of formulated oil was slightly higher than that of commercial oil. But the concentration of metal in the formulated oil, especially iron, were increased much less during test. The iron content of the commercial oil was increase rapidly from 7000 km while the formulated oil was still low. These results were conformed by the antiwear test by 4-ball wear test machine for the samples. Also for the commercial oil, the depletion factor of the Zn-DTP which was added as an antiwear property was not change any more after 7000 km. But the formulated oil was change continuously until 8000 km, which mean that the ability of wear protection of the sliding parts exists for the formulated oil. With the results which were analyzed of the properties of oils by field test, it was found that the commercial oil could be used only within 7000 km, but the formulated oil can use more than 8000 km without severe wear of the sliding parts in the diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.1
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• pp.1-15
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• 1996

This study is concerned with the property changes(chemical and mechanical) of the used oil in diesel engine, which were sampled from a test engine with dynamometer and various cars. The properties of oil are TAN, viscosity, oxidation, ZDTP depletion factor and etc. Also the relation between the change of chemical and antiwear property of used oil was strongly related to ZDTP depletion factor as wall as the change of TAN(total acid number), sulfation and pentan unsoluble contents which were reated to the formation of protect film in sliding area. The oil used in pick-up(small) truck engine was deteriorated within the shortest distance than that of other cars. The antiwear property of used oil was decreased sharply as the running distance were over 5,000km. The oil used to mini bus was the least to deteriorate of properities for the funning distance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.269-270
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• 2002

Antiwear(AW) properties of phoshphonic acid derivatives for trimethylolpropane (TMP) esters were investigated under boundary conditions. AW effect of dialkyl phosphonates depends on polarity of base fluid. They provide good AW performance in less polar TMP esters, whereas their AW effect is not sufficient in polar TMP esters. Amine salts of phosphonic acid were developed as new AW additiνe system for TMP esters. They provide excellent AW performance even in polar TMP esters.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.263-264
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• 2002

The tribological characteristic of several environmentally friendly lubricating base stocks was examined, and the effect of some commonly used additives on th tribological behavior of the lubricating oils was comparatively investigated on a four-ball machine. It has been found that the commercial additives including butene sulfide, wax chloride, zinc dialkyldithiophosphate and ashless P-N type agent helped to improve the friction-reducing and antiwear properties as well as the extreme pressure behavior. Non-toxic nanoscale $(CF)_x$ showed the best friction-reducing ability, though it registered relatively poor extreme pressure properties. The mechanism on friction of nano-scale material is discussed.

• Tribology and Lubricants
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• v.12 no.3
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• pp.6-11
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• 1996

There has been a growing concern for the use of mineral oil based lubricants because of the worldwide interest in environmental issues. This has prompted the use of vegetable oils as more environmentally acceptable base fluids. In view of this, four-ball wear test was carried out to investigate the tribological behavior of selected vegetable oils blended with ZDDP, TCP and DBP under high speed and temperate conditions. Of the additive evaluated, the new additive, DBP has provided antiwear performance superior to the two other additives more commonly used. This superior performance by DBP is probably caused by different wear mechanism. This wear mechanism has been evidenced by the surface analysis of worn balls conducted using optical microscope and EDAX.

• Tribology and Lubricants
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• v.19 no.6
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• pp.329-334
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• 2003

The antiwear properties of amphiphilic monolayers and composite multilayer on silicon surface were investigated using micro­tribometer and Auger Electron Spectroscopy. Langmuir­Blodgett (LB) monolayers from behenic acid, 2,4­heneicosanedione(HD) and its lopper complex((HD)$_2$Cu) were fabricated on silicon surface and the composite multilayer of 5­bilayer of (HD)$_2$Cu was fabricated on the surface of octadecyltrichlorosilane (OTS) self­assembled monolayer (SAM). We observed that LB monolayers and the composite multilayer exhibited a steady and excellent friction response when compared with the OTS SAM. These LB mono and multilayer also showed much higher wear­resistance than the OTS SAM.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1997.10a
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• pp.86-92
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• 1997

When Lubricants is used under severe running condition, tribological characteristics is very important. I have studied the lubricating oil viscosity, kinds of additives and lubricating oil temperatures were changed. In order to study the effect of oil temperature on the wear of the surface, the temperature of the oil was changed for the same sample. Moreover, the temperatures of three kinds of oils which have very different viscosities at room temperature, were varied while the oil viscosity was unchanged. It was shown from the test results that wear is not greatly affected by the amount of ZnDTP antiwear agent, but E-P additives are less effective against wear than ZnDTP additives. The viscosity of lubricating oil and its tempea-ature greatly affect the wear of the surface. Combining all the wear data with those of the surface strength, it was observed that the higher the load, the lower the scratch of wear, and also in the case of the same running load, the lower the wear, the longer the life of the surface strength.

• Tribology and Lubricants
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• v.17 no.4
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• pp.335-340
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• 2001

It was reviewed that the kinds of lubricating oil, viscosity, temperature and strength of materials affected the wear of the surface heat treatment. When lubricants is used under severe running conditions, their tribological characteristics are very important. We have studied the lubricating oil viscosity, kinds of additives and their amounts, and lubricating oil temperatures were changed. In order to study the effect of oil temperature on the wear of the surface, the temperature of the oil was changed for the same sample. It was shown from the test results that wear is not greatly affected by the amount of ZnDTP (Zinc dialkyl dithio phosphate) antiwear agent, but EP (Extreme pressure) additives are less effective against wear than ZnDTP additives. The viscosity of lubricating oil and its temperature greatly affect the wear of the surface. Combining all the wear data with those of the surface strength, it was observed that the higher the load, the lower the scratch of wear, and also in the case of the same running load, the lower the wear, the longer the life of the surface strength.