AVS 45th International Symposium
    Vacuum Metallurgy Division Monday Sessions
       Session VM-MoA

Paper VM-MoA4
Unbalanced Magnetron Sputtered Composite Metal-DLC Coatings

Monday, November 2, 1998, 3:00 pm, Room 328

Session: Plasma Assisted Surface Treatments and Coatings
Presenter: X.T. Zeng, Gintic Institute of Manufacturing Technology, Singapore
Correspondent: Click to Email
Composite metal-diamond like carbon (DLC) coating is an approach to achieve a combination of high hardness and toughness, good adhesion, a low friction coefficient, and a low wear rate, which is ideal for various tribological applications. Previous studies often used hydrocarbon gases to produce amorphous a:C-H coating doped with metal (Ti, W, Cr) and/or their nitrides by magnetron sputtering from metallic targets. Relatively high hardness (15 ~ 20 GPa) could be obtained in these coatings by increasing the doping level at the expense of an increasing friction coefficient which results in high wear rates. This paper reports the preparations of composite metal-DLC coatings on high speed steel substrates using unbalanced magnetron sputtering of both metallic and graphite targets. W and Ti/Cr targets were used to deposit both the bond layer and transition ceramic layer to support the surface composite DLC coating. For comparison, amorphous CN@sub x@ surface coating was also prepared for sliding wear testing. Nanoindentation and scratch tests were used to characterize the mechanical properties and pin-on-disk wear tests, using @phi@9 mm alumina as the pin and 10 N normal load, were carried out to evaluate the tribological properties of the coatings. Friction coefficient of about 0.06 ~ 0.1, at an air humidity of 40% RH, hardness of 15 ~ 18 GPa, critical load of about 65 N in scratch tests, and normalized wear rate of about 5 x 10@super -8@ mm@super 3@.N@super -1@.m@super -1@ for wearing for 38000 to 76000 cycles (3400 m to 6800 m) were measured. This wear rate is substantially lower than those of the nitride coatings. The superior wear resistance coupled with good adhesion implies that composite metal-DLC coatings could be good candidates for sliding wear applications.