Abstract:

Foam in lubricating oil increases wear between equipment, and reducing foam in oil can effectively reduce energy consumption. Representative hydrocarbon components of four mineral base oils were selected to construct a molecular simulation system of foam liquid film. The microscopic mechanism of the liquid film rupture process is analyzed through molecular dynamics simulations, and the rupture time of the one-component and mixed-component liquid film is calculated as the stability metric of the liquid film. On this basis, the effects of base oil structures, the additive and antifoam agent on the rupture time of oil-based foam film are analyzed. The results show that the appearance of initial holes in the process of liquid film rupture will significantly accelerate the rupture process. After adding additives and anti-foam agents to each base oil system, the change in the time of liquid film rupture was consistent with the change in diffusion coefficient, which was in line with the drainage mechanism of foam rupture. This work aims to analyze the stability and rupture mechanism of oil-based foams at the molecular level, and to explore ways to reduce the foam in lubricating oil.

Key words: mineral base oils, foam, rupture time, molecular simulation, antifoam agent

摘要：

润滑油中的泡沫会增加设备间的磨损，减少油品中的泡沫可以有效降低能源消耗。选用四种矿物型基础油的代表性烃类组分构建了泡沫液膜的分子模拟体系，通过分子动力学模拟分析了液膜破裂过程的微观机理，并计算了单组分及混合组分液膜的破裂时间作为液膜稳定性的评价指标。在此基础上，研究了基础油结构与添加剂、抗泡剂的加入对油基泡沫液膜破裂时间的影响。结果显示，在液膜破裂的过程中，初始孔洞的出现，会显著加快液膜破裂进程，在各基础油体系中加入添加剂、抗泡剂后，液膜破裂时间变化与扩散系数的变化一致，符合泡沫破裂的排液机理。提出的研究方法可从分子层面深入分析油基泡沫的稳定性及破裂机理，探索减少润滑油品泡沫的方法。

关键词: 矿物型基础油, 泡沫, 破裂时间, 分子模拟, 抗泡剂