Abstract Layered double hydroxides (LDHs) are a class of strongly adsorbed two-dimensional materials composed of divalent and trivalent metal cations. In this study, LDHs nanoplatelets with three different thickness were synthesized by changing the crystallization method during the hydrothermal reaction process. The three-dimensional size and layer number of nanoplatelets were confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The synthesized ultrathin Co/Al-LDH (U-CA-LDH) nanoplatelets, only ca. 1 nm thick (single or double layer), were surface modified with ethylene glycol for good dispersion in an oil-based system. As a lubricant additive, the base oil with U-CA-LDH nanoplatelets can withstand extreme pressures of up 2000 N, almost three times the ultimate load-bearing capacity for commercial additives. In particular, through physical property and chemical composition analysis of tribofilms, U-CA-LDH nanoplatelets with a partial tetrahedral coordination form were revealed to exhibit better tribological properties than multilayer Mg/Al-LDH (M−MA−LDH) nanoplatelets with a stable octahedral coordination form. Incomplete coordinated nanoplatelets exhibited extremely high chemical activity in the high-temperature tribological region and promoted the formation of a denser protective tribofilm on the sliding surface. Owing to their superior tribological properties as oil-based additives, U-CA-LDH nanoplatelets hold great potential for practical application in the mechanical industry in the future.

中文翻译：

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用作边界润滑剂的不同层 LDH 纳米片的优异极压性能

摘要 层状双氢氧化物（LDHs）是一类由二价和三价金属阳离子组成的强吸附二维材料。本研究通过改变水热反应过程中的结晶方法合成了三种不同厚度的LDHs纳米片。通过透射电子显微镜 (TEM) 和原子力显微镜 (AFM) 确认了纳米血小板的三维尺寸和层数。合成的超薄 Co/Al-LDH (U-CA-LDH) 纳米片，仅约 1 nm 厚（单层或双层），用乙二醇进行表面改性，以在油基体系中良好分散。作为润滑油添加剂，含有 U-CA-LDH 纳米片的基础油可承受高达 2000 N 的极压，几乎是商业添加剂极限承载能力的三倍。特别是，通过摩擦膜的物理性质和化学成分分析，部分四面体配位形式的 U-CA-LDH 纳米片显示出比多层 Mg/Al-LDH (M-MA-LDH) 纳米片更好的摩擦学性能。八面体配位形式。不完全配位的纳米片在高温摩擦学区域表现出极高的化学活性，促进了滑动表面上更致密的保护性摩擦膜的形成。由于其作为油基添加剂的优异摩擦学性能，U-CA-LDH纳米片在未来机械工业中具有巨大的实际应用潜力。具有部分四面体配位形式的 U-CA-LDH 纳米片显示出比具有稳定八面体配位形式的多层 Mg/Al-LDH (M-MA-LDH) 纳米片更好的摩擦学性能。不完全配位的纳米片在高温摩擦学区域表现出极高的化学活性，促进了滑动表面上更致密的保护性摩擦膜的形成。由于其作为油基添加剂的优异摩擦学性能，U-CA-LDH纳米片在未来机械工业中具有巨大的实际应用潜力。具有部分四面体配位形式的 U-CA-LDH 纳米片显示出比具有稳定八面体配位形式的多层 Mg/Al-LDH (M-MA-LDH) 纳米片更好的摩擦学性能。不完全配位的纳米片在高温摩擦学区域表现出极高的化学活性，促进了滑动表面上更致密的保护性摩擦膜的形成。由于其作为油基添加剂的优异摩擦学性能，U-CA-LDH纳米片在未来机械工业中具有巨大的实际应用潜力。不完全配位的纳米片在高温摩擦学区域表现出极高的化学活性，并促进了滑动表面上更致密的保护性摩擦膜的形成。由于其作为油基添加剂的优异摩擦学性能，U-CA-LDH纳米片在未来机械工业中具有巨大的实际应用潜力。不完全配位的纳米片在高温摩擦学区域表现出极高的化学活性，促进了滑动表面上更致密的保护性摩擦膜的形成。由于其作为油基添加剂的优异摩擦学性能，U-CA-LDH纳米片在未来机械工业中具有巨大的实际应用潜力。