Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Sci Rep. 2017 Aug 16;7(1):8426. doi: 10.1038/s41598-017-09029-z.
Ionic liquids (ILs) have recently been developed as a novel class of lubricant anti-wear (AW) additives, but the formation mechanism of their wear protective tribofilms is not yet well understood. Unlike the conventional metal-containing AW additives that self-react to grow a tribofilm, the metal-free ILs require a supplier of metal cations in the tribofilm growth. The two apparent sources of metal cations are the contact surface and the wear debris, and the latter contains important 'historical' interface information but often is overlooked. We correlated the morphological and compositional characteristics of tribofilms and wear debris from an IL-lubricated steel-steel contact. A complete multi-step formation mechanism is proposed for the tribofilm of metal-free AW additives, including direct tribochemical reactions between the metallic contact surface with oxygen to form an oxide interlayer, wear debris generation and breakdown, tribofilm growth via mechanical deposition, chemical deposition, and oxygen diffusion.
离子液体（ILs）最近被开发为一类新型的润滑剂抗磨（AW）添加剂，但它们的磨损保护摩擦膜的形成机制尚不清楚。与传统的自反应生成摩擦膜的含金属 AW 添加剂不同，无金属的 ILs 需要在摩擦膜生长过程中有金属阳离子的供应源。金属阳离子的两个明显来源是接触表面和磨屑，后者包含重要的“历史”界面信息，但经常被忽视。我们关联了 IL 润滑钢-钢接触的摩擦膜和磨屑的形态和组成特征。提出了无金属 AW 添加剂的摩擦膜的完整多步形成机制，包括金属接触表面与氧之间的直接摩擦化学反应，形成氧化物中间层，磨屑的生成和破裂，通过机械沉积、化学沉积和氧扩散进行的摩擦膜生长。
