Electric Field Effects on the Tribological Properties of Lubricants

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04247
• 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: Kansai University
• Principal Investigator: Lu Renguo 関西大学, システム理工学部, 教授 (90758210)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: トライボロジー / 電気自動車 / 摩擦の電気制御 / 摩耗の電気制御 / 潤滑油の分解

Outline of Final Research Achievements

The electrical failure of bearings has become a critical issue that restricts the lifetime of electric vehicles. This study aimed to explain the electrically induced tribological properties of lubricants. The direction of the electric current influenced friction coefficient, with a rapid increase observed when the cathode was connected to the sliding surface. The surface potential analysis showed that applying an electric current by connecting the friction surface to the cathode decreased surface activity, indicating that the effect of electric current on tribological properties depended on surface activity change. When an electric field was applied, low friction caused by molecular orientation could not be maintained, resulting in an increase in friction coefficient. Lubricant molecules charged by energization became unstable and reacted easily with the nascent surface, but it was far less than tribochemical decomposition, so electrical decomposition can be ignored.

Free Research Field

トライボロジー

Academic Significance and Societal Importance of the Research Achievements

本研究では、潤滑油のトライボロジー特性に及ぼす電流・電場の影響を調べた。学術的意義は、①表面電位法による電流が摺動面の表面活性への影響を明らかにしたこと、②FT-IRその場観察法による潤滑油分子挙動への電場の影響の明確ができたことと、③潤滑油分子の電気的な分解を解明することで、分子の吸着や分子配向などの分子レベルでの摩擦摩耗メカニズムを明らかにしたこと、の三点が挙げられる。本研究で得た成果は、電場の有効利用を促し、摩擦・摩耗特性を改善でき、産業界が悩まされてきた水素脆化型の早期転動疲労剥離の問題解決が可能となるほか、EV車や電気制御機械などの更なる性能向上への貢献も期待できる。