MECHANISM OF GREASE FILM FORMATION IN ELASTOHYDRODYNAMIC POINT CONTACTS

润滑脂已被广泛用作许多机器元件的润滑剂。然而，我们还不能在应用前准确地预测润滑脂的润滑性能。这是因为润滑脂在弹性流体动力润滑（EHL）体系中的行为尚未得到必要的理解。本研究的目的是利用光学干涉测量技术，在直接观察油脂膜的基础上，阐明点EHL接触中油脂膜形成的机理。作为试验润滑脂，使用由芳香、脂环和脂肪族三种不同增稠剂组成的无添加剂双脲脂脂。结果表明，增稠剂的结构对成膜和牵引特性的影响是巨大的。此外，还提出了新的油脂结构模型：芳香油脂的增稠剂分散在基础油中。脂肪脂是由增稠纤维缠结在一起形成的。脂环脂具有介于芳香脂和脂肪脂之间的中间纤维结构。其他重要结果总结如下：在增稠剂含量相同的情况下，脂环、芳香族、脂肪族油脂的总膜厚依次变薄。作为增稠剂之一，含脂肪族利尿的复合润滑脂的总膜厚与仅含脂肪族利尿的复合润滑脂的膜厚几乎相同。构成同一增稠剂结构的润滑脂的总膜厚随着基础油粘度的增加而增加。最大膜厚和最小膜厚主要分别由增稠剂和基础油的粘度决定。增稠剂与表面的粘附使膜的整体厚度变厚。增稠剂在表面的沉积和脱离是由表面之间的相对滑动控制的。粘附在表面上的增稠剂块表现为固体状材料，如表面凸起。饿死状态的发生取决于增稠剂的结构和基础油的粘度。牵引力系数变成。小的，芳香的，无脂的，无环的润滑脂。作为增稠剂之一，含脂肪族利尿的复合润滑脂的牵引力系数与仅含脂肪族利尿的润滑脂的牵引力系数基本相同。横向导向槽和长凸点对润滑脂EHL膜的影响与矿物油润滑EHL膜的影响基本相同。少

Greases have been widely used as lubricants for numerous machine elements. Nevertheless, we cannot yet predict lubricating performance of greases accurately in advance of the application. This is because the behavior of greases in elastohydrodynamic lubrication (EHL) regime has not been necessarily understood. The purpose of this study is to elucidate the mechanism of grease film formation in point EHL contacts hased on direct observations of grease films using the optical interferometry technique. As test greases, diurea greases, without additives, constituting of three different kinds of thickeners, i.e., aromatic, alicyclic and aliphatic diurca, were used. As a result, it has found that the thickener structure plays tremendous roles on the film formation and traction characteristics. Furthermore, new models of grease structures have been proposed : The thickener of aromatic grease is dispersed in the base oil. The aliphatic grease is composed of thickener fibers entangled together i … More n wide space. The alicyclic grease has intermediate fiber structures between the aromatic and aliphatic greases. The other important results obtained are summarized as follows :1. The overall film thicknesses of greases having the same thickener content become thinner in the order, alicyclic, aromatic, aliphatic greases.2. The overall film thickness of combined grease containing aliphatic diurea as one of the thickeners is almost the same as that of grease containing only aliphatic diurea.3. The overall film thicknesses of greases constituting of the same thickener structure increase as the base oil viscosity increases.4. The maximum and minimum film thicknesses are mainly determined by the thickener and viscosity of the base oil, respectively.5. The adhesion of thickener to the surfaces brings about thick overall film thickness.6. The deposition and detachment of thickener to and from the surfaces are controlled by the relative sliding between surfaces.7. The thickener lump adhered to the surfaces behaves as a solid-like material such as a surface bump.8. The occurrence of the starved condition depends on the thickener structure and viscosity of the base oil.9. The traction coefficient becomes .smaller in the order, aromatic, ahiphatic, ahicyclic greases.10. The traction coefficient of combined grease containing alipliatic diurca as one of the thickeners is almost the same as that of grease containing only aliphatic diurea.11. The effects of a transversely oriented groove and a long bump on grease EHL films are basically the same as those on EHL films lubricated by mineral oils. Less