In this work, the advantage of Coulomb repulsion in the intermolecular forces experienced by molecules on the solid-liquid nanosized contact interface is taken, and the superior friction-reducing property of Cu₃(PO₄)₂·3H₂O (CuP) oil-based additives has been confirmed for titanium alloy. Three-dimensional (3D) CuP nanoflowers (CuP-Fs) with a strong capillary absorption effect are prepared to achieve the homogeneous mixing of solid CuP and lubricating oil. Lubrication by CuP-Fs additives for titanium alloy, friction coefficient (COF) can be reduced by 73.68%, and wear rate (WR) reduced by 99.69%. It is demonstrated that the extraordinary friction-reducing property is due to the repulsive solid-liquid interface with low viscous shear force originating from Coulomb repulsion between polar water molecules in CuP and non-polar oil molecules. However, any steric hindrance or connection between this repulsive solid-liquid interface will trigger the adhesion and increase the viscous shear force, for example, dispersant, hydrogen bondings, and shaky adsorbed water molecules. Besides, the lamellar thickness of CuP and the molecular size of lubricant both have a great influence on tribological properties. Here the lubrication mechanism based on interface Coulomb repulsion is proposed that may help broaden the scope of the exploration in low-friction nanomaterial design and new lubricant systems.

本工作利用固液纳米接触界面上分子所受分子间力的库仑斥力优势，以及Cu ₃ (PO ₄ ) ₂ ·3H ₂ O (CuP)油优异的减摩性能钛合金中的添加剂已被证实。制备具有强毛细管吸收效应的三维（3D）CuP纳米花（CuP-Fs），实现固体CuP与润滑油的均匀混合。 CuP-Fs添加剂对钛合金的润滑，摩擦系数（COF）可降低73.68%，磨损率（WR）降低99.69%。结果表明，非凡的减摩性能是由于 CuP 中极性水分子与非极性油分子之间的库仑斥力产生的具有低粘性剪切力的排斥性固液界面。然而，这种排斥性固液界面之间的任何空间位阻或连接都会引发粘附并增加粘性剪切力，例如分散剂、氢键和不稳定的吸附水分子。此外，CuP的片层厚度和润滑剂的分子尺寸都对摩擦学性能有很大影响。这里提出了基于界面库仑斥力的润滑机制，这可能有助于拓宽低摩擦纳米材料设计和新型润滑系统的探索范围。