In Situ Formed Ionic Liquids in Polyol Esters as High Performance Lubricants for Steel/Steel Contacts at 300 掳C

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• 作者：Xinhu Wu ; Junming Liu ; Qin Zhao ; Ming Zhang ; Gaiqing Zhao ; Xiaobo Wang
• 刊名：ACS Sustainable Chemistry & Engineering
• 出版年：2015
• 出版时间：September 8, 2015
• 年：2015
• 卷：3
• 期：9
• 页码：2281-2290
• 全文大小：763K
• ISSN：2168-0485

文摘

In situ formed ionic liquids (ILs) as high temperature lubricants can be obtained by mixing polyol esters (pentaerythritol oleate or trihydroxymethylpropyl trioleate) with lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) in molar ratios of 1/0.5, 1/1 and 1/1.5. Thermal and rheological analysis indicate that the in situ formed ILs, [Li(polyol ester)]TFSI, with various molar ratios are more resistant to high temperatures and substantially stronger than the polyol ester base oils. Tribological results revealed that these in situ forming ILs with molar ratios of 1/1 and 1/1.5 possessed excellent friction reduction and antiwear performance for steel/steel contact at 300 掳C. Moreover, their tribological properties were significantly better than the pure polyol ester base oils and perfluoroalkyl polyether (PFPE, as a reference lubricant) under the same conditions. The results of SEM-EDS show that tribo-films formed on the worn steel discs surface lubricated by [Li(polyol ester)]TFSI. The XPS analytical results further proved the formation of a boundary lubrication films which composed of Fe₂O₃, Fe₃O₄, Fe(OH)O, FeF₂, FeSO₄ or Fe₂(SO₄)₃ and C鈥揙 bonding. This surface-protective film is believed to be responsible for the excellent tribological performances of in situ forming ILs using at elevated temperature.