• 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.

• 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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• 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.

• Journal of the Korean Chemical Society
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• v.23 no.1
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• pp.52-58
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• 1979

Metallic dialkyldithiophosphates are widely used in lubricating oils as antioxidant and antiwear agents. Zinc DDTP are used most frequently in lubricating oil. Zinc, lead, tin and cobalt DDTP were prepared with primary and secondary alkyl groups. The effects of oxidation, thermal stability, metal corrosion and antiwear of each metallic DDTP prepared were studied. Based on the results, cobalt DDTP has a significant effect of antiwear on chrome alloy steel comparing with the other metallic DDTP. Also cobalt DDTP has a characteristic property of thermal sensitivity in its color, which was shown by the color change from brown to blue over a certain temperature. Another phenomenon obtained was that all metallic DDTP initiates the effect of antioxidation at the time of reaching to a certain effective acid concentration in lubricating oil.

• Tribology and Lubricants
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• v.7 no.1
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• pp.46-54
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• 1991

As the additives of engine oil, Mo-DTP and Zn-DTP were studied by experimental works. These additives were added to the engine oil with various ratios, which was an attempt to find out the best ratio at which the wear and friction can be reduced effectively; Mo-DTP is belived to be able to decrease the frictioh of the sliding metal, while Zn-DTP is known as a very stable additive for oxidation at high temperature in addition to the good antiwear property. This study showed that the optimum addition ratio of Mo-DTP and Zn-DTP is 3:2. This oil made it possible to slide steel with minimum wear and low friction over various lovels of load at moderate temperature. But as the oil temperature increased, the wear slid with Mo-DTP oil was increased more. The reason of this result was that Mo-DTP deteriorated the property of oil at high temperature by the higher oxidation and viscosity of Mo-DTP oil than that of Zn-DTP oil.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.3
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• pp.51-59
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• 2001

A diesel engine oil formulated in KRICT and a commercial diesel engine oil (API CG-4) were tested by car and their Kinematic Viscosity, TAN, TBN, metal content, additive depletion, anti-wear property and IR analysis were analyzed. From the research, both of the tested oils had almost the same properties f3r the change of TAN and TBN, but the change of Kinematic Viscosity of formulated oil was slightly higher than that of commercial oil. The iron content in the commercial oil increased rapidly from 7000 km while that of the formulated oil was still low. These results were confirmed by the anti-wear test with a 4-ball wear test machine for the each samples. Also, for the commercial oil, the depletion factor of the Zn-DTP which was added as an anti-wear property did not change any more after 7000 km. But, that of the formulated oil changed continuously to 8000 km, which means that the ability to prevent wear of the sliding pairs exists for the formulated oil. From the analysis results of oil properties obtained by field test, it was found that the commercial oil could be used only within 7000 km, but the formulated oil could be used 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.1 no.2
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• pp.89-102
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• 1993

In this experimental investigation, various plasma-sprayed zirconia contained coatings and a kind of alumina-zirconia coating were studied to gain a better understanding of their tribological behaviour under dry contact condition in a reciprocating motion at temperature of 200℃. Particular attention was made for finding appropriate coatings in cylinder liner/piston ring application with an emphasis on the antiwear property. In order to identify the wear mechanism, SEM(Scanning Electron Microscope), optical micrograph, and roughness tester were used. Alumina-zirconia and 8% yttria-zirconia were found to be most appropriate for the application to the cylinder liner/piston ring and, especially, alumina-zirconia exhibited highest wear-resistance and also showed good friction characteristics. Wear mechanisms of ceramic coatings identified.