Effect of Oiliness Agent on Lubricity of DLC Coating

Abstract

Diamond-like carbon (DLC) is used as a superior material in various fields because of its several excellent properties, such as high hardness, low friction coefficient and so on. DLC coating has good lubricity without lubricant, but it could show better lubricity by using lubricant. Therefore, we investigated an effect of the oiliness agent on the friction properties of the DLC coating. The friction tests were carried out by using a reciprocating ball-on-disk wear tester. Lubricant is composed of 10 mass% oiliness agent and 90mass% hydrocarbon oil. The friction coefficient of the DLC coating was decreased by using lubricant. And the oiliness agents were classified into three groups by friction properties. Glycerin monooleate (GMO) showed the lowest friction coefficient of all oiliness agents at all temperatures in this experiment. It was considered that GMO was adsorbed on the DLC surface stronger than the other oiliness agents. It was estimated that alcohol part in ester effects on adsorption of these oiliness agents.

Keywords

• dlc coating
• oiliness agent
• friction coefficient
• glycerin monooleate
• alcohol
• ester