コハク酸イミド分散剤がATF油中摩擦におけるトライボ被膜の生成に及ぼす影響

抄録

To elucidate the mechanism for suppressing wear of high-speed bearing steel (SUJ2) used in automatic transmission fluid (ATF), friction and wear tests were conducted in lubricating oils containing different concentrations of succinimide dispersant. The wear volume of the SUJ2 disk in the base oil was approximately 1.4×10⁴mm³. However, with the addition of 0.75 wt.% of succinimide dispersant, the wear volume decreased to about 0.4×10⁴mm³, approximately one-third of the original amount. In Fluid A and Fluid A I₀.₇₅-I₂.₇₅, the reduction in wear volume was observed only in Fluid A I₀.₇₅. This was believed to be due to the presence of succinimide dispersant, which led to the formation of iron oxide within the wear scars, and on the surface, FeS and FeS₂formed as tribofilms. In the case of Fluid A I₀.₇₅, the film hardness was higher, contributing to improved wear resistance. The sole reason for the increased hardness of the tribofilm in Fluid A I₀.₇₅was hypothesized to be the repeated friction of the tribofilm within the surface, leading to the deposition of FeS and FeS₂. This, in turn, was presumed to enhance the density of the tribofilm.