摩擦诱导纳米润滑剂在界面控制释放及其智能润滑机制研究

High efficient and durable lubrication of metalworking fluid is one of the key factors to improve the machining efficiency of difficult-to-process materials such as titanium alloy. The poor dispersion and short lubricating time of nano-lubricant in metalworking fluid is designed to be solved in this project. Based on the systematic studies of the tribological behavior of nano-molybdenum disulfide and according to the idea of environmental protection and solid-liquid synergistic lubrication, this project explores the methods of using friction-induced physical and chemical effects to control active lubrication. A kind of environmental-sensitive microgel will be prepared as the lubricants of esterified bio-oil based metalworking emulsion. During the process of continuous cutting, the oil molecules desorb from the frictional interfaces due to the rise of the friction temperature in mechanical process or the organic acids dissociate from the metalworking fluid, which results in the insufficient or invalid lubrication. The microgel will automatically shrink and will induce the controlled release of nano-lubricant to improve the lubrication performance, realizing smart lubrication and in-situ regulation of the cutting process. The inner relationship among the frictional conditions, composite structures of the microgel and tribological properties will be focused. The variation of friction and wear behavior of typical titanium alloy materials under metalworking fluid lubrication will be explored by using modern surface analysis technology. The controlled release mechanisms of the nano-lubricant, the synergistic effects of the components and the smart lubrication mechanisms will be revealed, which can provide the necessary theoretical support and technical guidance for the active lubrication control of green metalworking fluid during the continuous cutting process.

金属加工液高效持久润滑是提高钛合金等难加工材料机械加工效率的关键因素之一。本项目针对纳米润滑剂在金属加工液中难分散与润滑时效短的问题，在系统研究纳米二硫化钼摩擦学行为基础上，立足环保与固-液协同润滑思路，探索利用摩擦诱导的物理与化学效应设计主动润滑控制方法。通过制备一类具有环境敏感性的复合微凝胶作为酯化生物油基金属加工液润滑添加剂，当连续切削过程摩擦升温引发油液分子在摩擦界面脱附或有机酸游离出现润滑不足或失效时，微凝胶自动收缩，诱导纳米润滑剂在界面控制释放来改善润滑，实现切削过程智能润滑与原位调控；本项目将重点研究“摩擦条件-微凝胶复合结构-摩擦学特性”之间的内在联系，利用现代表面分析技术，深入探索典型钛合金材料在金属加工液润滑下摩擦磨损行为变化规律，阐明纳米润滑剂的控释机理、各组分协同作用机理以及智能润滑机制，为绿色金属加工液在连续切削过程主动润滑调控提供必要的理论支撑和技术指导。

为了改善难加工材料钛合金等机械加工过程的润滑问题，本项目设计并合成了几种复合微凝胶作金属加工液润滑添加剂以改善纳米润滑剂的分散性，增强润滑效果，并借助其环境敏感性，在摩擦过程自动释放纳米润滑剂至摩擦界面，实现智能润滑。项目系统考察了几种重要聚合物微凝胶的分散性能及润滑性能，总结了微凝胶结构与润滑性能之间的关系；明晰了复合微凝胶各组分之间以及微凝胶与油液分子之间的相互作用机制；实现了典型纳米润滑剂在金属加工液中智能润滑与主动控制。研究发现：（1）通过工艺调控，可以合成并有效控制聚合物微凝胶尺寸在数十至数百纳米，并且在微凝胶引入聚N-异丙基丙烯酰胺成分可使得微凝胶获得温度敏感性，引入聚丙烯酸成分可使得微凝胶获得pH敏感性。（2）所制备的微凝胶在金属加工液水相体系以及牛血清体系中均表现出良好的分散性，且有显著的减摩抗磨润滑作用，在特定工况下系统的摩擦系数和磨损量分别可降低50%与70%以上。（3）随温度升高，微凝胶在金属加工液水相体系中表现出摩擦系数先增大后降低趋势，这与微凝胶在低临界溶液温度下结构塌陷有关；而微凝胶在牛血清溶液中则表现为摩擦系数先降低后增大趋势，这与滑液蛋白分子在低临界溶液温度时吸附到微凝胶表面，与微凝胶共同发挥润滑作用有关。（4）复合微凝胶在金属加工液摩擦过程中受摩擦温升或pH降低影响，分子链段自动收缩，释放纳米润滑剂至摩擦界面，增强界面润滑性能，在钛合金连续切削过程可实现纳米润滑剂的持续补充，从而达到持久高效的智能润滑效果。这些研究成果将为金属加工液对难加工材料加工过程高效润滑提供重要数据参考与科学指导。在本项目支持下，目前已发表相关SCI论文16篇，申请国家发明专利12项（已授权10项），获得科研奖励3项，培养博士毕业1人、硕士毕业7人、在读硕士生7人。