In situ instrumentation for localized wear studies of magnetic thin-film disks

Abstract

An experimental set-up and a procedure to make in situ localized measurements of various wear processes on magnetic thin-film disks are developed. The coefficient of friction, acoustic emission and optical reflectance are monitored simultaneously. Results are analysed to determine ‘precursors to failure’ and to compare the effects of lubricant, surface roughness, overcoat and normal load on disk wear. Disk wear is observed to follow a pattern of lubricant depletion followed by head slider-overcoat asperity contact. Wear tracks are formed after asperity contact. Lubricant extends disk wear life, as does a polished surface texture, and an SiO₂ overcoat wears more slowly than a diamond-like carbon overcoat. The experimental methodology developed in this study should be of interest in studying precursors to failure of any moving interface.

Keywords

magnetic disk head acoustic emission optical sensor strain gauge friction and wear

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