| Summary: | The effects of episulfidation on the frictional properties of mononuclear molybdenum dithiocarbamates having azaheterocycles were investigated. It was shown that the friction coefficients of the lubricants with the episulfided mononuclear molybdenum dithiocarbamates, as measured by the SRV friction test, were lower than those with non-episulfided ones. The friction coefficients of episulfided compounds are also similar to that of binuclear molybdenum dithiocarbamate, which is frequently used as friction modifier in lubricants in actual practice. The extent of decrease in friction in the SRV test differed with the number of carbon atoms in the azaheterocycles of the molybdenum compounds, suggesting that the thermal stability of the compounds affected the friction characteristics of the tested oils. The results from EPMA surface analyses of the disks from the SRV tests suggest that episulfidation of the molybdenum compounds led to effective formation of molybdenum disulfide film by the corresponding oils during the friction tests.
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