Wear mechanisms of amorphous carbon and zirconia coatings on rigid disk magnetic recording media

Examination of the durability of zirconia-coated rigid disks in various environments reveals a sensitivity to the presence of water vapor during sliding, similar to that of carbon-coated rigid disks. Among the test environments investigated, i.e. vacuum, dry/moist air, and moist nitrogen, humidity had the greatest effect by increasing the contact life of the disks substantially over that of vacuum or dry air. The dominant factors affecting wear are believed to be oxidation of metallic debris and interaction of the overcoat layer with water vapor. Tests with ferrite read/write sliders on carbon-coated disks suggest that the pin-on-disk test is a valid simulation of the tribological behavior of this system. Carbon film thickness measurements indicate that the carbon film remains intact without appreciable thinning until the point of failure.