Direct measurement of the adsorption force and shear resistance of oxides in oil and elucidation of the wear mechanism under lubrication

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03831
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18040:Machine elements and tribology-related
• Research Institution: University of Fukui
• Principal Investigator: Honda Tomomi 福井大学, 学術研究院工学系部門, 教授 (80251982)
• Co-Investigator(Kenkyū-buntansha): 福島 啓悟 福井大学, 学術研究院工学系部門, 講師 (50725322)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: メンテナンストライボロジー / 油中酸化物 / 吸着力直接測定 / 吸着シミュレーション / 潤滑摩耗

Outline of Final Research Achievements

Lubricating oil is deteriorates with use, it not only loses its functions but also causes breakdowns and malfunctions of machine and equipment. In particular, it is lubricating oil that has been oxidized forms insoluble and sticky polymerized products in the oil, which cause sticking and damage to sliding surfaces. In this study, lubricating oils that have been simulated oxidized were prepared, and the size of the adsorbate of the lubricating oil oxides to solid surfaces and the frictional properties of the adsorbate were investigated using an atomic force microscope. As a result, the adsorption force and amount of the sample oil with a higher degree of oxidation increased due to the increase or polymerization of the adsorbate on the sample surface. It was also clarified that the oxide adsorbed on the sample surface behaved like fatty acids up to a certain amount. Still an excessive increase in oxide resulted in a higher friction coefficient.

Free Research Field

トライボロジー

Academic Significance and Societal Importance of the Research Achievements

トライボロジーの研究分野において，油潤滑下での摩耗機構と摩耗の起点となる油の酸化との因果関係について，その根源まで遡ることによるメカニズムの解明は行われてこなかった．また，機械設備の故障を未然に防ぐためには，摩擦摩耗の起点となる潤滑油の劣化，特に酸化進行メカニズムと酸化した油分子の摩擦面への吸着メカニズムの解明が鍵となる．これに対して，油の酸化物が固体表面に付着するメカニズムやその付着力およびせん断強度が摩擦抵抗の増大や摩耗に及ぼす影響を提示できた．さらに，分子動力学シミュレーションを用いて粘性係数の解析を行い，分子の極性の有無による比較を行い，摩擦・力学的特性の評価を行えることを示した．