固/液界面润湿性对线接触油膜润滑的影响

Effect of Wettability of Solid/Liquid Interface on Film Lubrication in Line Contact

目的优化表征固/液界面的表征参数。方法应用AF和FAS修饰柱面滑块以获得不同润湿性的表面,并测量PEG200、150N和PAO6三种润滑油在AF、FAS和SiO2表面上的接触角、接触角滞后以及三种表面的表面自由能。通过对线接触润滑油膜厚的测量,评价固/液界面润湿性与油膜厚度的关联性。结果润滑油为PEG200或150N时,在SiO2/SiO2接触副产生的油膜厚度高于SiO2/FAS接触副,而且接触角越小,油膜厚度越大;接触角滞后越大,油膜厚度越大。PEG200、150N和PAO6润滑油分别在SiO2/SiO2和SiO2/AF同一接触副时,呈现出几乎相同的油膜厚度。此时,接触角滞后与油膜厚度的关联性优于接触角。此外,润滑油在AF表面测得的接触角最大且接触角滞后最小,但产生的油膜厚度最大,该现象可以归因于油膜承载力/厚度与界面强度的非单调性。结论在线接触流体动压润滑条件下,固/液界面的润湿性能够影响油膜厚度。界面表征参数接触角和接触角滞后,与油膜厚度的关联性都存在一定的局限性,但相对而言,接触角滞后的范围更大。AF界面特性与油膜厚度的关系,证明了疏油表面可以具有较好的成膜能力。

The work aims to optimize the characterization parameters of solid/liquid interface.AF and FAS were used to modify the cylinder slider to obtain the surface with different wettability and contact angle,contact angle hysteresis and surface free energy were measured between engineering surfaces(AF,FAS and SiO2)and lubricating oil(PEG200,150N and PAO6).The correlation between the wettability of the solid/liquid interface and the lubricant film thickness was evaluated by measuring the film thickness of line contact.With lubricating oil of PEG200 or 150N,the film thickness produced by SiO2/SiO2 contacts was higher than that of SiO2/FAS contacts.In this situation,the film thickness increased with the decrease of contact angle and the increase of contact angle hysteresis.The lubricating oil PEG200,150N and PAO6 showed almost the same film thickness in the same contact pair SiO2/SiO2 or SiO2/AF,respectively.The correlation between contact angle hysteresis and film thickness was better than that between contact angle and film thickness.For AF coating,contact angle was the maximum,contact angle hysteresis was the minimum,but the lubricant film thickness was the maximum.This phenomenon could be attributed to the non-monotony of the bearing capacity/thickness of the lubricant film and the interface strength.Under the condition of line contact hydrodynamic lubrication,the wettability of solid/liquid interface can affect the thickness of oil film.The correlation between interface characterization parameters such as contact angle and contact angle hysteresis and film thickness is limited to some extent,but the range of contact angle hysteresis is relatively wide.The relationship between AF interface characteristics and film thickness proves that the oleophobic surface also has a good film-forming ability.