Friction and wear properties in dry, water- and oil-lubricated DLC against alumina and DLC against steel contacts

Helena Ronkainen, Simo Varjus, Kenneth Holmberg

    Research output: Contribution to journalArticleScientificpeer-review

    225 Citations (Scopus)


    Diamond-like carbon (DLC) films can be divided into two major categories according to their hydrogen content.
    These categories have similarities in tribological performance, but the films also behave in a different manner in different tribological conditions.
    The results of amorphous hydrogenated carbon films (a-C:H) and hydrogen-free hard carbon films (a-C) are reported in this study. The a-C:H films were deposited using the radio frequency (rf) plasma technique, and the hydrogen-free hard carbon films using pulsed vacuum arc.
    The coatings were characterized and investigated with respect to their tribological performance in dry (50% RH), water-lubricated and oil-lubricated slow sliding conditions (0.004 m s−1). The a-C and a-C:H films had a low friction coefficient in dry sliding conditions (0.15 to 0.22), which was further decreased by 10–40% under boundary lubrication.
    The a-C:H(Ti) films exhibited good self-lubricating properties (0.10) in dry sliding conditions and the a-C films had the lowest friction coefficient in water- (0.03) and oil-lubricated (0.08) conditions.
    The hydrogen-free hard carbon films showed excellent wear resistance in dry, water- and oil-lubricated conditions, but hydrogenated a-C:H films suffered from severe wear in aqueous conditions.
    The performance of a-C:H films could be improved by titanium alloying. In dry sliding conditions, the tribolayer formation of DLC films influenced the friction and wear performance, but in oil-lubricated conditions boundary lubrication layers were formed, which governed the tribological mechanisms in the contact.

    Original languageEnglish
    Pages (from-to)120-128
    Issue number2
    Publication statusPublished - 1998
    MoE publication typeA1 Journal article-refereed


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