Nanometer-Scale Distribution of a Lubricant Modifier on Iron Films: A Frequency-Modulation Atomic Force Microscopy Study Combined with a Friction Test
Nanometer-Scale Distribution of a Lubricant Modifier on Iron Films: A Frequency-Modulation Atomic Force Microscopy Study Combined with a Friction Test
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润滑油改性剂在铁膜上的纳米级分布：调频原子力显微镜研究与摩擦测试相结合
DOI：
10.1021/acsomega.9b02821
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发表时间：
2019
期刊：
影响因子：
4.1
通讯作者：
Onishi Hiroshi
中科院分区：
文献类型：
--
作者：
Moriguchi Shiho;Tsujimoto Teppei;Sasahara Akira;Kokawa Ryohei;Onishi Hiroshi
机械应用中使用的液体润滑剂是用少量极性化合物改性的低蒸气压碳氢化合物。当滑动表面很接近时，吸附在滑动固体表面上的极性改进剂对摩擦性能起主导作用。然而，有几种方法可用于表征纳米级厚度的吸附改性剂。在这项研究中，我们应用调频原子力显微镜来评估吸附在真实润滑剂中的改性剂的纵向和横向密度分布，即用正磷酸油酯改性的聚α-烯烃(PAO)。探头上的液体诱导力被映射到垂直于润滑剂-铁界面的平面上，力敏感度约为10pN。在没有酯类改性剂的情况下，PAO直接暴露在薄膜上，产生了几个平行于薄膜表面的液层，层与层之间的距离为0.6-0.7 nm。随着主体润滑剂中酯浓度的增加，改性剂的单分子层被间歇地吸附，完全覆盖范围为20ppm。在润滑剂中波动的油酯的C18H35链对尖端产生排斥力，并随着尖端到表面的距离单调衰减。用摩擦试验机分别测定了滑动钢-润滑剂-钢界面的动摩擦系数，并与浸泡在相应润滑剂中的铁膜上的力图进行了比较。在静态润滑剂-铁界面上形成完整的酯类改性剂单分子层是在滑动界面上实现平稳摩擦的必要条件。
Liquid lubricants used in mechanical applications are low-vapor-pressure hydrocarbons modified with a small quantity of polar compounds. The polar modifiers adsorbed on the surface of sliding solids dominate the friction properties when the sliding surfaces are in close proximity. However, a few methods are available for the characterization of the adsorbed modifiers of a nanometer-scale thickness. In this study, we applied frequency-modulation atomic force microscopy to evaluate the vertical and lateral density distributions of the adsorbed modifier in a real lubricant, namely, poly-α-olefin (PAO) modified with an orthophosphoric acid oleyl ester. The liquid-induced force on the probing tip was mapped on a plane that was perpendicular to the lubricant–iron interface with a force sensitivity on the order of 10 pN. The PAO in the absence of the ester modifier was directly exposed to the film, which produced a few liquid layers parallel to the film surface with layer-to-layer distances of 0.6–0.7 nm. A monomolecular layer of the modifier was intermittently adsorbed with increasing ester concentration in the bulk lubricant, with complete coverage seen at 20 ppm. The C18H35chains of the oleyl esters fluctuating in the lubricant produced a repulsive force on the tip, which monotonically decayed with the tip-to-surface distance. The dynamic friction coefficient of sliding steel–lubricant–steel interfaces, which was separately determined using a friction tester, was compared with the force map determined on the iron film immersed in the corresponding lubricant. The complete monomolecular layer of the ester modifier on the static lubricant–iron boundary is a requirement for achieving smooth and stable friction at the sliding interface.
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溶剂化并挤出十六烷在石墨上。
影响因子：
4.4
作者：
N. Gosvami;S. Sinha;W. Hofbauer;Sean J. O’Shea
通讯作者：
Sean J. O’Shea
影响因子：
3.7
作者：
Hofbauer, W.;Ho, R. J.;O'Shea, S. J.
通讯作者：
O'Shea, S. J.
影响因子：
3.7
作者：
Takumi Hiasa;K. Kimura;H. Onishi
通讯作者：
Takumi Hiasa;K. Kimura;H. Onishi
液体十六烷/石墨界面的实验三维描述。
DOI：
10.1021/la803665k
发表时间：
2009
期刊：
Langmuir : the ACS journal of surfaces and colloids
影响因子：
--
作者：
L. P. Van;V. Kyrylyuk;Jérôme Polesel;F. Thoyer;C. Lubin;J. Cousty
通讯作者：
J. Cousty
DOI：
10.1007/s11249-018-1041-y
发表时间：
2018
期刊：
Tribology letter
影响因子：
--
作者：
Marc;G. Krämer;U. Dellwo;R. Bennewitz
通讯作者：
R. Bennewitz