ZDDPトライボフィルムの成長に及ぼす先端曲率半径の影響

抄録

A typical anti-wear additive, zinc dialkyldithiophosphate (ZDDP), has been utilized for many types of lubricants. ZDDP is known to form reaction film by direct contact between sliding two substrates and protects adhesion wear. However, there are few reports about in situ observation of tribofilm formation due to difficulty in investigating the formation process of the tribofilm in nanoscale. Recently, Gosvami et al. observed the growth process of the tribofilm formed by ZDDP at the contacts of single asperities using a novel in-situ atomic force microscopy (AFM) method and suggested that increasing contact pressure and temperature promoted the growth of ZDDP tribofilm. In addition, we confirmed the promoting of tribofilm growth by increasing surface roughness. However, the promoting parameter on tribofilm growth has not been revealed. In this study, we used seven steel sample with different roughness and conducted in-situ AFM in ZDDP containing oil at 120 ℃. As a result, we confirmed the summit radius influenced the growth rate of ZDDP tribofilm. This suggests that the summit radius is a key parameter of tribofilm growth.