Physiochemical properties of tribofilms generated from octadecylthioperoxydiphosphate (SSC18) and octadecylphosphorofluoridothioate (PFC18) were compared with zinc dialkyl dithiophosphates (ZDDP) in this study. PFC18 and SSC18 were chemically synthesised and mixed in mineral base oil to prepare test oil formulations. Additionally, PFC18 and SSC18 were mixed at different concentrations and evaluated for their compatibility and tribological performance using high frequency reciprocating rig (HFRR) tribometer. All lubricant formulations with ashless additives exhibited superior anti‐wear characteristics compared to ZDDP. Comprehensive surface analysis of tribofilms was conducted using scanning electron microscopy, nano‐indentation and X‐ray absorption near edge spectroscopy. Formulations containing only SSC18 and PFC18 exhibited a uniform and continuous tribofilm formation, while formulations with a combination of SSC18 and PFC18 had a stable pad‐like structure. X‐ray absorption near edge structure (XANES) results indicate ashless PFC18 and SSC18 by themselves and in combination form iron phosphate enriched tribofilms with a mixture of iron sulfides and/or sulfates.

中文翻译：

---

无灰二硫代磷酸酯抗磨添加剂的相互作用形成的摩擦膜的化学和物理性质

在这项研究中，比较了由十八烷基硫代过氧二磷酸酯（SSC18）和十八烷基磷酸氟代硫代磷酸酯（PFC18）生成的摩擦膜的理化性质。化学合成PFC18和SSC18，并与矿物基础油混合以制备测试油配方。此外，将PFC18和SSC18以不同的浓度混合，并使用高频往复钻机（HFRR）摩擦计评估其相容性和摩擦学性能。与ZDDP相比，所有含无灰添加剂的润滑剂配方均具有卓越的抗磨性能。使用扫描电子显微镜，纳米压痕和近边缘光谱X射线吸收法对摩擦膜进行了全面的表面分析。仅包含SSC18和PFC18的制剂表现出均匀而连续的摩擦膜形成，而结合使用SSC18和PFC18的制剂具有稳定的垫状结构。X射线在边缘结构附近的吸收（XANES）结果表明，无灰的PFC18和SSC18本身以及与硫化铁和/或硫酸铁混合物形成的富含磷酸铁的摩擦膜结合在一起。