The effect of emulsifier concentration on the lubricating properties of oil-in-water emulsions
The effect of emulsifier concentration on the lubricating properties of oil-in-water emulsions
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DOI：
10.1007/s11249-006-9072-1
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发表时间：
2006-04-01
影响因子：
3.2
通讯作者：
Spikes, H. A.
中科院分区：
文献类型：
--
作者：
Cambiella, A.;Benito, J. M.;Spikes, H. A.
虽然水包油（O/W）乳状液作为金属加工液的使用很普遍，但乳状液润滑的机理还没有很好地理解。关于O/W型乳状液的润滑性能与操作条件和乳状液性质的关系，已有多种理论提出，但目前还没有明确的一致意见。在本研究中，O/W乳液的成膜能力作为乳化剂浓度的函数进行了研究。乳化剂含量对所有乳液性质，如稳定性、液滴尺寸分布、表面和界面张力、润湿能力等都有很大影响，以及润滑性能，因此它已被用来确定所有相关性能之间的关系。在润滑油O/W乳状液的设计中，以不同的浓度使用阴离子、非离子和阳离子三种不同的乳化剂。实验结果表明，油滴在金属表面的粘附功是一个有价值的参数，以预测在弹性流体动力学（EHD）接触的乳状液形成厚膜的能力。同时也证实了O/W型乳状液的pH值对其润滑性能的影响。总的结论是，金属和油滴之间的相互作用规则的润滑机制，这种相互作用主要是由乳化剂浓度控制。
Although the use of oil-in-water (O/W) emulsions as metalworking fluids is widespread, the mechanisms of emulsion lubrication are not yet well understood. Several theories have been proposed but there is not a clear agreement about the effect of different operating conditions and emulsion properties on the lubricating performance of O/W emulsions. In the present study, the film forming ability of O/W emulsions as a function of emulsifier concentration is studied. The emulsifier content exerts a strong influence on all the emulsion properties, such as stability, droplet size distribution, surface and interfacial tension, wetting ability, etc., as well as on the lubricating behaviour, so it has been used to ascertain the relationship between all the properties involved. Three different emulsifiers-anionic, nonionic and cationic-were used at different concentrations in the design of lubricant O/W emulsions. Experimental results show that the work of adhesion of oil droplets on the metal surface is a valuable parameter to predict the ability of emulsions to form thick films in elastohydrodynamic (EHD) contacts. The influence of pH value of O/W emulsions on their lubricating behaviour is also verified. The overall conclusion is that the interactions between metal and oil droplets rule the mechanism of lubrication and that this interaction is primarily controlled by emulsifier concentration.