【作者】 马丽然；

【导师】 雒建斌；

【作者基本信息】 清华大学 ， 机械工程， 2010， 博士

【摘要】 水基润滑液由于其良好的应用前景被广泛应用于制造业、生物润滑及微型机械等领域。与传统油润滑不同,水基润滑特性及机理均有待进一步研究和完善。以水包油（O/W）型乳化液为例,虽然已广泛应用于金属加工领域,但对其成膜机理的研究至今尚无定论,有待进一步深入研究。本文的主要工作之一是研制了适用于水基润滑研究的测试系统,并对测量方法（相对光强法）进行了分析、验证和改进。纳米级水基润滑膜厚摩擦综合测试系统实现了不同滑滚比下纳米级润滑膜的实时观测及膜厚的自动精确定位测量、加载及转动的自动控制和调节、操作系统的人性化和自动化等功能,该系统具有较高的分辨率和测量精度,为水基润滑特性及机理的研究奠定了基础。对含有微量油水的成膜特性的研究结果表明,即便水中含有极微量的油时(<1×10^-3vol%),其成膜能力仍远高于传统弹流润滑理论所预测的纯水成膜能力。本文通过对油水分子在固体界面上竞争行为的分析,利用竞争润湿的理论,对上述现象的机理进行了分析,并对不同固体表面及供液方式对微量油润滑的影响进行研究。设计了微量油润滑的作用方式,为微量油润滑的可行性提供了实验依据。在对O/W型乳化液成膜特性的研究中,针对具有不同参数的乳化液进行试验,结果表明,乳化液成膜特性与供液方式、运动速度、乳化剂浓度及油浓度密切相关。在对其成膜机理的研究中,以超低浓度乳化液为研究对象,发现乳化液的临界速度随乳化液浓度变化发生变化,结合对接触区附近乳化液液滴行为的观测,提出二次乳化机理,并建立理论模型进行验证。提出乳化液膜厚的下降并非单纯由传统理论提出的乏油作用引起,乳化液本体对固体表面油层的二次乳化效应在其成膜中起到了很大作用。对液滴在接触区附近行为的观测为乳化液成膜机理的研究提供了实验基础。通过大量实验和理论研究深入地分析了乳化液的成膜机理。此外,0.0005%浓度乳化液在一定条件下形成高达100nm润滑膜的结果也为微量油润滑的可行性提供了有力的依据。更多还原

【Abstract】 Although the water-based lubricant has a wide application in many fields, such as metal processing, biological lubrication, micromachine, and so on, the film formation characteristics and mechanism are still dubious. As to the oil-in-water emulsion, which has been widely used in metal working, the film formation mechanism needs further discussion and research in spite of numerous previous studies.In this study, a testing set-up system has been developed for observation and film-thickness measurement of water-based lubrication, and the relative optical interference intensity technique has been validated and improved. By using this system, thickness and the state of the lubricant film at nanometer scale under point contact with different sliding ratios can be measured and real-time traced. The loading and rotating systems both can be automatically controlled. The locating measurement for the film thickness was also developed. Thus, measurement with high resolution and precision can be obtained. Therefore, the testing system lays the foundation of the study on water-based lubrication in point contacts.In the research for the lubrication of water with micro content of oil, different surfaces and liquid feeding modes were adopted. A relatively high film thickness was obtained in the experiment although the oil volume concentration was extremely low (<1×10^-3%), which does not agree with the traditional EHL （elastohydrodynamic lubrication） theory. The film forming ability attributes to the the micro content of oil contamination. The competitive wetting behavior of water and oil on the surface was investigated to explain the mechanism, which premises for the feasibility of micro-content-oil lubrication.The film formation of oil-in-water emuslion under point contact was found to be sensitive to the feeding mode, rolling speed, emulsifier and oil concentration. The critical speed of film thickness was detected to be effected significantly by the oil concentration by ultilizing emulsion with micro content of oil. The observation of the emulsion flow surrounding the contact area was carried out for direct explanation of the film formation mechanism. Reemulsification effects near the contact area were raised for the film formation mechanism based on the modeling validation. During the investigation, good film formation ability can be obtained when the oil concentration is lower than 0.5%. An emulsion film about 80nm can be obtained at 1m/s when the oil concentration is 0.0005%, which provides effective experiemental evidence for the micro-oil-content lubrication.更多还原