ZnDTPとFM共存下の摩擦特性と吸着特性に関する研究

抄録

Friction reduction by engine oil under low and high temperature conditions is required because of the increasing number of hybrid vehicles where oil temperature is low. Friction modifier (FM) technology to realize it are required. Friction performance of molybdenum dithiocarbamate (MoDTC) used with adsorption type FMs was investigated, which showed different results depending on types of adsorption type FMs: glycerol monooleate (GMO) inhibited friction reduction while polymer FM (PFM) did not. To understand the cause of the difference, the effect of reaction film formation by Zinc dithiophosphate (ZnDTP), which is crucial for the friction reduction by MoDTC, on adsorption type FMs was investigated. GMO inhibited the reaction film formation by ZnDTP, while PFM did not fully, observed with mini-traction machine spacer layer imaging (MTM-SLIM) and EPMA analysis. The cause was studied by their adsorption performance examined by quartz crystal microbalance (QCM). GMO showed higher adsorption density, while PFM showed lower compared to that of ZnDTP. The result indicated that GMO competitively adsorbed on the surface, inhibiting the reaction film formation by ZnDTP while polymer FM did not. Adsorption performance under co-existence of PFM and ZnDTP indicated that ZnDTP is capable to adsorb on the surface under the existence of PFM. The study indicated that the key to achieve low friction is to use PFM which does not fully inhibit ZnDTP reaction film formation.