Coating characteristics and tribological properties of sputter-deposited MoS2/metal composite coatings deposited by closed field unbalanced magnetron sputter ion plating☆

As previously reported (V.C. Fox, N.M. Renevier, D.G., Teer, J. Hampshire, V. Rigato, Proceedings of the PSE Conference in Garmisch Partenkirchen, 14–18 September 1998, Germany, Surf. Coating Technol., in press) the properties of MoS2 coatings deposited by closed field unbalanced magnetron sputter ion plating (CFUBMSIP) can be improved by the co-deposition of a small amount of titanium. These MoS2/Ti composite non-multilayer coatings known as MoST™, are harder (10–15 GPa) and more adherent (critical load scratch above 120 N), much more wear resistant (10−16–10−17 m3/mN), and higher load bearing (3.5 GPa) than pure MoS2 coatings. They have similar low friction to pure MoS2 coating (μ of 0.02 at 40% humidity) but are much less sensitive to atmospheric water vapour during tribological testing at high humidity. MoS2/Ti composite coatings have given excellent industrial results for a wide range of cutting and forming applications. Other metal additions such as Cr, W, Mo and Zr have been studied with varying compositions and substrates. Laboratory test results using micro hardness and nanoindentation testing, scratch adhesion testing, pin on disc and reciprocating friction and wear tests are presented. Structural analysis was carried out using X-ray diffraction, optical microscopy, scanning electron microscopy and transmission electron microscopy of cross-sections through the coating. This paper presents further analysis on the MoS2/Ti composite coatings and with other metal additions such as chromium, tungsten or zirconium.