低面坮境界潤滑における摩擦俿数の速度依存性に関する研究（第2報）: 酸性リン酸エステル添加による速度依存性発琭メカニズムの考察

摘要

It was found that, in a previous report, the velocity-dependent property of friction appears under low sliding velocity and low contacting pressure condition if acid phosphate with long chain alkyl is added to lubricating oil. In this paper, some experiments to elucidate mechanism of strong velocity-dependent property of friction are conducted. Variations of electric resistance of contact point with the sliding velocity and friction with temperature suggest existence of thick viscous boundary film because the film thickness increases with increasing into the sliding velocity and the friction decreases with increasing into temperature. Furthermore, it is found that the asperity contact is in elastic state because the plasticity index ψ of the sliding surface after well-running-in process was very low. Consequently, it is considered that the strong velocity-dependent property of friction, when lubricated with the oil containing alkyl acid phosphate, is mainly originated from viscous force of the thick viscous boundary film.%工作機械で用いられるすべりガイドは専用の潤rn滑油を用いることで，極低速での摩擦係数が非常rnに低く境界潤滑衡域ですべり速度増加に対して摩rn擦係数が増加する傾向を示す．本研究はこのよrnうな境界潤滑領域での摩擦係数の速度依存性が発rn現するメカニズムを解明することを目的としていrnる．前報では，境界潤滑領域での摩擦係数の速rn度依存性が明確に見られる添加剤は長鎖アルキルrn基を有した酸性リン酸エステルであることが明らrnかとなった．