オレイン酸潤滑下すベリ摩擦におけるDLC膜の摩擦低減特性とトライボ化学反応の関係

摘要

Diamond-Like Carbon (DLC) coating provides low friction properties without lubricants and, with lubricants such as organic acid, should provide ultra low friction. In this study, the friction property of two types of DLC coating, which were hydrogenated amorphous carbon (a-C:H) by the Plasma-Enhanced Chemical Vapor Deposition (PECVD) process and tetrahedral amorphous carbon (ta-C) by the T-Shaped Filtered Arc Deposition (T-FAD) process, were evaluated with oleic acid lubrication. It was found that friction coefficient of ta-C with deuterated oleic acid lubrication provided much lower than that of a-C:H. The tribo-film on wear track was analyzed by time-of-flight secondary ion mass spectrometer and X-ray photoelectron spectroscopy. As a result, it was found that larger amount of C-0 and C=0 bond derived from oleic acid were detected in the upper layer of tribo-film formed on the sliding surface of ta-C disc. It was suggested that difference of friction property between a-C:H and ta-C seemed to be caused by different composition of tribo-film generated during sliding.%金属材料しゅう動部の摩擦摩耗低減を目的として，多種多様な硬質表面コーティング技術が開発されており，その一つであるDiamond-Like Carbon(DLC)コーティングは，自動車エンジン部品をはじめとする様々な機械部品への適用が進んでいる.また潤滑剤との組合せによる，顕著な低摩擦化事例も報告されている.我々は，水素あり，水素なしの2種類のDLC (a-C:Hおよびta-C)を用いて，これまでに軸受鋼とDLC,またはDLC同士のすべり接触において，低炭素数のカルボン酸である乳酸や，高炭素数のカルボン酸であるオレイン酸潤滑下での超低摩擦特性について報告を行ってきた.