Study of lubricating agents adsorption on DLC coatings using neutron reflectometry - Taiho Kogyo Research Foundation, Japan
Project duration
2010 - 2012
Project Category
international
Contact Information
Partners
- Doshisha University (Japan)
Diamond-like carbon (DLC) coatings have proven to be one of the most promising types of coatings for protection of surfaces in tribological contacts. With the use of neutron reflectometry, atomic force microscopy and real tribological tests the project addresses the problem of adsorption of oils and additives (alcohols, carboxylic acids) on different types of DLC coatings and the influence of chemical composition and structure of oils and additives on the adsorption and lubrication properties of these coatings.
Diamond-like carbon (DLC) coatings are distinguished by their low friction, good antiwear properties and protection against adhesion, so the interest in them and their usage in the last decade are dramatically increasing. However, the knowledge on the mechanisms and the influence of lubrication oils and additives on DLC coatings is still scarce. It is believed that the problems related to lubrication of DLC coatings result due to their nonreactivity, since the assumed inertness limits and sometimes even prevents reactions with existing lubricants and additives in the boundary lubrication conditions. This project addresses the problem of adsorption of base oils and additives (with active functional groups: alcohols, carboxylic acids) on different types of DLC coatings, and the effect of chemical composition and structure of oils and additives on a completely molecular level. The project is based on research using neutron reflectometry, atomic force microscopy (AFM) and real tribological tests. With the neutron reflectometry the presence of adsorbed molecules can be revealed and the thickness of adsorbed layers estimated. AFM studies serve as verification and further explanation of the findings revealed by neutron reflectometry. It also provides other important information, such as the strength of adsorption, occupation of adsorption sites, etc. The results of these "ex-situ" methods are compared with the "in-situ" results of tribological tests in dynamic conditions. Thus, by using modern high-tech methods on macro- and nano-scale we can study lubricating mechanisms, which enables us to obtain a reliable adsorption model of boundary lubrication of DLC coatings.