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S1140103 Tribological properties of tetrahedral amorphous diamond-like carbon film under boundary lubrication in presence of organic friction modifiers and ZnDTP

2014; Japan Society Mechanical Engineers; Volume: 2014; Linguagem: Inglês

10.1299/jsmemecj.2014._s1140103-

2424-2667

H. Ōkubo, Chiharu Tadokoro, Shinya Sasaki,

Tribology and Wear Analysis

The tetrahedral amorphous carbon (ta-C) DLC coating showed superlow friction behavior under the boundary lubrication with an organic friction modifier such as glycerol mono-oleate (GMO). On the other hand, there are many reports about the tribological properties of DLC coatings under lubrication with zinc dialkyldithiophosphate (ZnDTP) added oils. The effect of ZnDTP, however, showed quite different tribological properties depending on the type of the DLC films. Lubrication mechanism of ZnDTP against the DLC films has not yet been realized completely. In this research, we studied the effects of ZnDTP additives on the tribological properties of ta-C coating under the boundary lubrication with oils which contain organic friction modifiers. The tribological properties were evaluated by using a reciprocating type cylinder-on-disk tribo-tester (SRV-4). Friction tests were carried out for the tribo-pair of DLC/DLC under lubrication with PAO and PAO-based oils containing GMO, GME, TDEA, ZnDTP, GMO + ZnDTP, GME + ZnDTP and TDEA + ZnDTP additives. From the experimental results, ta-C film showed an exhibited low friction coefficient between 0.02 - 0.05 under lubrication with PAO-based oils containing organic friction modifiers. However, the combination of GMO + ZnDTP and GME + ZnDTP lead to a higher increase of friction coefficient and wear volume compared to ZDDP-free PAO oils containing organic friction modifiers. On the other hand, the combination of TDEA and ZnDTP showed a lower friction coefficient of 0.03.