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Abstract
Experimental investigations were performed to study the effect of environmental conditions on the tribology of the head/disk interface for laser textured and mechanically textured hard disks. Based on tribological tests and bearing characterization analysis of the two types of media, a physical model was proposed to explain the different stiction behavior of the two types of hard media.
A model based on the meniscus theory of stiction and Hertz's theory of elastic contact was developed to numerically compute stiction and laser bump deformation as a function of hard disk design parameters, including the areal density, height, size, and curvature of the laser bumps, the effective area of contact between slider and the disk, and the disk lubricant thickness. The model was found to be in good agreement with experimental results.
The deformation mode (elastic/plastic deformation) of laser bumps for contacts between a head and a hard disk was analyzed for laser textured media with crater-shaped bumps. A new plasticity index and a deformation mode criterion for crater-shaped laser bumps were developed to determine whether head/disk contacts are elastic or plastic.
Investigations were also carried out to evaluate additives that improve the tribological performance and thermal stability of Z-DOL, the primary disk lubricant. Based on tribological experiments with several lubricants, it was found that X-100, a phosphazene-type lubricant, is similar to X-1P, an additive used in Z-DOL, in improving the tribological performance of Z-DOL. Since X-100 has better solubility than X-1P in Z-DOL and thus less phase separation than X-1P in Z-DOL, X-100 is proposed as a good alternative to the use of X-1P. Along with other tribological investigations, the effect of X-100 on the thermal stability of Z-DOL was also investigated using thermal gravity analysis.
