Chemistry of Interfaces, Luleå University of Technology, S-97187 Luleå, Sweden.
ACS Appl Mater Interfaces. 2011 Apr;3(4):956-68. doi: 10.1021/am101203t. Epub 2011 Mar 22.
Boron compounds have become of interest in tribology because of their unique tribochemical and tribological properties. At the same time, dialkyldithiophosphates (DTPs) of transition metals have been extensively used as multifunctional additives in lubricants to control friction and reduce wear in mechanical systems. Because of the environmental pollution and health hazards of these compounds, ashless compounds with reduced amounts of sulfur and phosphorus are desirable. This work reports on the synthesis, characterization, and tribological properties of a new class of compounds, alkylborate-dithiophosphates. This class combines two high-iron-affinity surface active groups, borate and dialkyldithiophosphate, into a single molecule. The final products, viscous liquids, were characterized by FT-IR, multinuclear (1)H, (13)C, (31)P, and (11)B NMR spectroscopy and thermal analyses. Residues of one representative compound from this class, DPB-EDTP, after thermal analyses were additionally characterized by multinuclear (13)C, (31)P and (11)B MAS and (31)P CP/MAS NMR spectroscopy. Solid-state NMR data suggest that a dominant part of the solid residue of DPB-EDTP consists of borophosphates. Antiwear and friction properties of a mineral oil with these novel additives were evaluated in a four-ball tribometer in comparison with O,O'-di-n-butyl-dithiophosphato-zinc(II), Zn-BuDTP, as a reference lubricant additive. The surface morphology and the elemental composition of the tribofilms were characterized using scanning electron microscopy with energy-dispersive X-rays spectroscopy (SEM/EDS). The results show that alkylborate-dithiophosphates, with substantially reduced amounts of sulfur and phosphorus compared with Zn-BuDTP, have considerably better antiwear and friction performance.
硼化合物因其独特的摩擦化学和摩擦学性质而成为摩擦学领域的研究热点。与此同时，过渡金属的二烷基二硫代磷酸酯（DTPs）已被广泛用作润滑剂中的多功能添加剂，以控制机械系统中的摩擦和减少磨损。由于这些化合物对环境的污染和对健康的危害，人们希望使用含硫和磷量较低的无灰化合物。本工作报道了一类新型化合物——烷基硼酸二硫代磷酸酯的合成、表征和摩擦学性能。这类化合物将两个高铁亲和力的表面活性剂基团硼酸和二烷基二硫代磷酸酯结合到一个分子中。最终产物为粘性液体，通过傅里叶变换红外光谱（FT-IR）、多核（1）H、（13）C、（31）P 和（11）B NMR 光谱和热分析进行了表征。此类化合物中一个代表性化合物 DPB-EDTP 的热分析残留物，还通过多核（13）C、（31）P 和（11）B MAS 和（31）P CP/MAS NMR 光谱进行了表征。固态 NMR 数据表明，DPB-EDTP 固体残留物的主要部分由硼磷酸盐组成。将这些新型添加剂与 O,O'-二正丁基二硫代磷酸锌（II）（Zn-BuDTP）作为参考润滑剂添加剂在四球摩擦试验机中评估了它们在矿物油中的抗磨和摩擦性能。使用带有能量色散 X 射线光谱（SEM/EDS）的扫描电子显微镜（SEM）对摩擦膜的表面形貌和元素组成进行了表征。结果表明，与 Zn-BuDTP 相比，含硫和磷量大大减少的烷基硼酸二硫代磷酸酯具有更好的抗磨和摩擦性能。
