著者

中村 健太 村木 正芳 中津 賢治

出版者

一般社団法人 日本トライボロジー学会

雑誌

トライボロジスト (ISSN:09151168)

巻号頁・発行日

vol.66, no.3, pp.220-228, 2021-03-15 (Released:2021-03-15)

参考文献数

14

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Influence of alkyl group of primary zinc dialkyldithiophosphate (ZDDP) on the friction and wear properties was studied using two different kinds of ZDDPs under the boundary lubrication condition with a pin-on-disk type tribotester. A coefficient of friction (COF) was determined under the following three operating conditions: the constant condition, the step-load condition and the variable-speed condition. COF of linear-alkyl ZDDP showed lower value than that of branched-alkyl ZDDP under all these conditions. Nano-friction force of the tribofilm obtained in the constant condition test was measured by means of an atomic force microscope. Meanwhile, nano-friction force ratio of the branched type to the linear type was almost same as COF ratio. It was suggested that macro-scale frictional behaviour was governed by nano-scale mutual interaction of tribofilms. On the other hand, the wear scar diameter decreased with increasing ZDDP concentration. From the energy dispersive X-ray spectroscopy analysis, the wear scar diameter was inversely correlated with phosphorus concentration on the worn surface. These results suggested that COF depended on mechanical properties of top layer of tribofilm while wear resistance depended on the thickness of base layer of tribofilm containing polyphosphate.