葫芦[7]脲作为水基润滑添加剂的摩擦学性能研究

Tribological Behavior of Cucurbit[7]uril as Lubricant Additive in Water-based fluids

合成了葫芦[7]脲化合物,用核磁共振、元素分析和红外光谱对其结构进行了表征,用同步热分析仪测定了其热稳定性,在SRV-IV摩擦磨损试验机上评价了其作为水及水/乙二醇润滑体系的添加剂在室温下对钢/钢摩擦副的润滑性能,用X射线光电子能谱仪(XPS)研究了其润滑机理.结果表明:葫芦[7]脲具有非常优异的热稳定性能、初始热分解温度在360℃以上;作为水基润滑体系的添加剂能有效地提高体系的减摩抗磨性能,使得体系的摩擦系数由0.30左右降低到0.20左右,磨损率降低50%;根据XPS分析结果,我们推测其优异的润滑性能主要归因于葫芦[7]脲通过羰基氧原子与摩擦副表面带正电荷的金属离子之间的静电作用吸附在磨损表面而形成的物理吸附膜.

Cucurbit[7]uril(CB[7]) was synthesized and characterized by nuclear magnetic resonance,elemental analysis and Fourier transform infrared spectroscopy. Its thermal property was determined by simultaneous thermogravimetry. The tribological capacity of cucurbit[7]uril as lubricant additive in water-based fluids(H2O and H2O/ethylene glycol) for steel/steel contact at room temperature was evaluated by an Optimol SRV-IV tester. X-ray photoelectron spectrometer(XPS) analysis was carried out to explore the lubrication mechanism. The results suggest that cucurbit[7]uril has high thermal stability with an onset decomposition temperature of more than 360 ℃. Cucurbit[7]uril as lubricant additive can effectively improve the friction-reducing and anti-wear properties of water-based fluids. When cucurbit[7]uril was added,the friction coefficient decreased from about 0. 30 to 0. 20 and the wear rate reduced by more than 50%. Based on the XPS analysis,it can be deduced that the good lubrication of cucurbit[7]uril was mainly attributed to the generation of physical adsorption films on the sliding surface through electrostatic attraction between the carbonyl groups of cucurbit[7]uril and the positive charge occupied steel surfaces.