The lubrication of DLC coatings with mineral and biodegradable oils having different polar and saturation characteristics

Kalin, Mitjan (author), Vižintin, Jože (author), Vercammen, K. (author), Barriga, J. (author), Arnšek, Aleš (author)

Due to improved performance over the last decade, diamond-like carbon (DLC) coatings are more frequently used in highly loaded mechanical components that sometimes need to operate under boundary- or mixed-lubrication conditions. However, DLC coatings are considered as "inert" coatings with a low surface energy and their lubrication ability according to conventional metal-lubrication mechanisms is therefore questionable. In order to investigate whether the base oil polarity and saturation characteristics play a role in these processes, a tribological investigation of the a-C:H coating lubricated with natural (sunflower) and synthetic (saturated and un-saturated)biodegradable oils that posses different amount of polar components and double bonds was performed. For a comparison we also used mineral base oil with low polar component. The DLC/DLC and steel/steel contacts were tested with base oils without additives and in combination with AW and EP additives. Despite the higher wear compared to steel/steel contacts,the results suggest that the wear of DLC/DLC contacts can be importantly improved by using oils with more polar groups and non-saturated molecules. These findings, together with well-known and even proverbial "low-friction properties", suggest a great potential for the use of DLC coatings in combination with biodegradable oils, particularly when additives are present.

• Language: English
• Keywords: DLC coatings, biodegradable oil, lubrication, polarity, saturation, wear, friction
• Work type: Not categorized (r6)
• Tipology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Year: 2006
• Number of pages: str. 4515-4522
• Numbering: Letn. 200, št. 14/15
• UDC: 621.793:621.89
• ISSN on article: 0257-8972
• COBISS.SI-ID: 9063451
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Record is a part of a journal

• Title: Surface & coatings technology
• Shortened title: Surf. coat. technol.
• Publisher: Elsevier Sequoia
• ISSN: 0257-8972
• COBISS.SI-ID: 3084815