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

---

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.

著者

村木 正芳 中村 健太 鈴木 真 瀬上 高博 山本 賢二

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.59, no.8, pp.507-514, 2014-08-15 (Released:2018-02-23)

参考文献数

11

---

Tribological performances of the oils containing polylaurylacrylates with and without hydroxyethyl group were studied under elastohydrodynamic lubrication (EHL), partial EHL and the boundary lubrication conditions. The base oil was polyalphaolefin and the viscosity of polymer solutions and the concentration of polymer was adjusted at the same level. Under the partial elastohydrodynamic contacts using a ball-on-disk type tribometer, polylaurylacrylatehydroxyethylacrylate (PLA/HEA) showed a greater oil film thickness while lower traction coefficient at low rolling speeds than polylaurylacrylate (PLA). This can be interpreted that adsorption of hydroxyethyl group of PLA/HEA reduced traction under the partial EHL condition. Under the boundary lubrication conditions using a pin-on-disk type tribometer, PLA/HEA exhibited the flat friction-velocity relation while PLA showed a large negative gradient of friction-velocity relation. Finally, PLA/HEA was superior to PLA in terms of the antiwear properties with a reciprocating friction tester. It is inferred that these better performances of PLA/HEA under the boundary lubrication conditions were brought about by formation of a tribofilm based on reaction of hydroxyethyl group and the sliding surface.

著者

村木 正芳 木村 好次

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. C編 (ISSN:03875024)

巻号頁・発行日

vol.55, no.520, pp.3048-3055, 1989-12-25

被引用文献数

1

---

Analysis is present of EHL traction with low-viscosity lubricating oils, which is the case encountered at higher temperatures. Extension is made of the approximate formula already derived by the authors, where it is assumed that viscosity, instead of viscoelasticity, predominates when the limiting Newtonian viscosity in an EHL film falls below a critical value, 10^5 Pas, and an Eyring viscous solution is employed. The rheological parameters representing the traction characteristics of an oil then become the effective viscosity-pressure coefficient and the representative stress, and they are expressed as functions of mean Hertzian pressure and bulk temperature. Calculated results are compared with experimental data obtained on a four-roller machine for two diesters showing close agreement.