To decrease wear and friction, zinc dialkyldithiophosphate (ZDDP) has been used in engine oil for several decades, but the mechanism of the tribofilm formation is still unclear. The purpose of this study is to characterize the chemical details of the tribofilm by using high-resolution approaching.,An ISO VG 100 mineral oil mixed with ZDDP was used in sliding tests on cylindrical roller bearings. Tribofilm formation was observed after 2 h of the sliding test. X-ray photoelectron spectroscopy (XPS) and atom probe tomography (APT) were used for chemical analysis of the tribofilm.,The results show that the ZDDP tribofilm consists of the common ZDDP elements along with iron oxides. A considerable amount of zinc and a small amount of sulfur were observed. In particular, an oxide interlayer with sulfur enrichment was revealed by APT between the tribofilm and the steel substrate. The depth profile of the chemical composition was obtained, and a tribofilm of approximately 40 nm thickness was identified by XPS.,A sulfur enrichment at the interface is observed by APT, which is beneath an oxygen enrichment. The clear evidence of the S interlayer confirms the hard and soft acids and bases principle.,The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2020-0035/

中文翻译：

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通过 X 射线光电子能谱和原子探针断层扫描揭示 ZDDP 摩擦膜的界面性质

为了减少磨损和摩擦，二烷基二硫代磷酸锌 (ZDDP) 已在发动机油中使用了几十年，但摩擦膜形成的机制仍不清楚。本研究的目的是通过使用高分辨率接近来表征摩擦膜的化学细节。将 ISO VG 100 矿物油与 ZDDP 混合用于圆柱滚子轴承的滑动测试。在滑动测试 2 小时后观察到摩擦膜形成。X射线光电子能谱（XPS）和原子探针断层扫描（APT）用于摩擦膜的化学分析。结果表明ZDDP摩擦膜由常见的ZDDP元素和氧化铁组成。观察到大量的锌和少量的硫。特别是，摩擦膜和钢基材之间的 APT 揭示了富含硫的氧化物夹层。获得了化学成分的深度剖面，并通过 XPS 识别出约 40 nm 厚的摩擦膜。通过 APT 观察到界面处的硫富集，其位于富氧之下。S 夹层的明确证据证实了软硬酸碱原理。,本文的同行评审历史可在：https://publons.com/publon/10.1108/ILT-01-2020-0035/