Abstract:

Grease is commonly used to safeguard the operation of bearings and its lubrication is affected by the temperature rise effect. This paper investigated the influence of temperature on the lubricating performance of grease. The influence of the high-temperature thermal action on the grease performance was investigated from the perspective of film formation, and the mechanism was revealed in conjunction with the rheological behavior. Firstly, the thermal degradation experiments were carried out to simulate the bearing operation process, and the grease was subjected to static heat treatment for 4h, 8h and 24h at 80℃, 120℃ and 150℃, respectively. Secondly, the film thickness of different experimental conditions was measured using an optical EHL film test rig, and the minimum oil film thickness was used to evaluate the film-forming performance. Finally, the mechanism was explored in relation to the rheological behavior of the samples. The results indicated that the high-temperature thermal effect changed the film-forming performance. When the working temperature was lower than the limit temperature, it was favourable to the film-forming process. The film-forming performance of grease became weaker as the temperature increased because the high-temperature thermal effect changed the structural system of grease, which in turn influenced its film-forming performance. Moreover, the synergistic between soap fibers and base oils was the most beneficial for film formation. The results of this work can provide reference and data support for the evaluation of service reliability and failure analysis of greases.

Key words: grease, high-temperature thermal action, rheological properties, film-forming properties, structural system

摘要：

润滑脂是轴承常用工业润滑剂之一，然而其在服役过程中的润滑效果受温升效应影响。为进一步系统研究温度对润滑脂润滑性能的影响，从润滑脂成膜角度探究高温热效应对其性能的影响规律，并结合流变学行为揭示变化机理。首先，在80℃、120℃、150℃的温度条件下分别进行4h、8h、24h的静态热处理模拟润滑脂承受高温热作用。其次，利用光弹流润滑油膜测量仪研究不同实验条件下的膜厚变化规律，采用最小油膜厚度评价成膜性能。最后，结合样品的流变学行为探究其变化机理。研究结果表明：高温热效应将会对润滑脂成膜性能产生影响，正常运转下的温度效应利于润滑脂的成膜，随着温度的升高，润滑脂的成膜性能将会被削弱，其原因在于高温热效应对润滑脂的结构体系产生影响，进而改变其成膜性能，润滑脂的皂纤维与基础油协同作用对润滑脂的成膜最为有利。研究结果为润滑脂服役可靠性评价和失效分析提供了实验参考和数据支撑。

关键词: 润滑脂, 高温热效应, 流变特性, 成膜性能, 结构体系