WEAR CHARACTERISTICS IN THIN-FILM MEDIA

This paper focuses on the influence of sublayer mechanical properties on tribological phenomena affecting thin-film media. To isolate the influence of individual sublayers, disks used in this investigation possessed fewer layers than commercial media. Pin-on-disk experimentation was performed to investigate friction and wear of r.f.-sputtered carbon deposited on two different substrates: an Al 5086 disk possessing a hard NiP coating, and a softer and more ductile Al 1100 disk. The C/NiP disk had an apparent wear rate lower than the C/Al 1100 disk. The friction forces measured during testing were found to exhibit differences in trend and magnitude. The C/Al 1100 disk produced mean friction curves which increased rapidly and subsequently levelled off. The friction curves of the C/NiP disk showed a tendency to increase slowly and steadily throughout the test. During the early stages of the wear process, the C/Al 1100 disk displayed substantial plastic deformation or ploughing of the track region. Failure of the overcoat occurs through fracture and delamination of the carbon film. During the wear process, the C/NiP disk displayed evidence of adhesive wear. After a large number of passes, abrasive wear became a significant contributing wear mechanism.