Adsorption of alcohols and fatty acids onto hydrogenated (a-C:H) DLC coatings

Simič, Rok (author), Kalin, Mitjan (author), Kovač, Janez (author), Jakša, Gregor (author)

Information about the interactions between lubricants and DLC coatings is scarce, despite there having been many studies over the years. In this investigation we used ToF-SIMS, XPS and contact-angle analyses to examine the adsorption ability and mechanisms with respect to two oiliness additives, i.e., hexadecanol and hexadecanoic acid, on an a-C:H coating. In addition, we analyzed the resistance of the adsorbed films to external influences like solvent cleaning. The results show that both molecules adsorb onto surface oxides and hydroxides present on the initial DLC surface and shield these structures with their hydrocarbon tails. This makes the surfaces less polar, which is manifested in a smaller polar component of the surface energy. We also showed that ultrasonic cleaning in heptane has no significant effect on the quantity of adsorbed molecules or on their chemical state. This not only shows the relatively strong adsorption of these molecules, but also provides useful information for future experimental work. Of the two examined molecules, the acid showed a greater adsorption ability than the alcohol, which explains some of the previously reported better tribological properties in the case of the acid with respect to the alcohol.

• Language: English
• Keywords: DLC coatings, adsorption, alcohols, fatty acids, ToF-SIMS, XPS, wetting
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Author Accepted Manuscript
• Year: 2016
• Number of pages: Str. 466-476
• Numbering: Vol. 363
• PID: 20.500.12556/RUL-106734
• UDC: 539.92(045)
• ISSN on article: 0169-4332
• DOI: 10.1016/j.apsusc.2015.12.066
• COBISS.SI-ID: 14399003
• Publication date in RUL: 14.03.2019

Record is a part of a journal

• Title: Applied surface science
• Shortened title: Appl. surf. sci.
• Publisher: Elsevier
• ISSN: 0169-4332
• COBISS.SI-ID: 3283215

Secondary language

• Language: Slovenian
• Keywords: mazanje, alkohol, adsorpcija, DLC prevleke

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P2-0231
• Name: Tribologija