Raman Spectroscopy and Nano Hardness Investigation of Carbon Overcoats Used in Hard Disks and Sliders

This paper investigates structural and mechanical properties of present carbon overcoats for a number of sliders and disks manufactured by various vendors. Raman spectroscopy is first used to identify the morphology of the carbon overcoats and to evaluate to what extend the carbon films show differences for films manufactured by different vendors. In addition, characterization of the mechanical properties of the films is made using atomic force microscopy.In addition to Raman spectroscopy, nano hardness measurements were performed for all sliders and disks to verify the predictions. In this investigation, the effect of ultrasonic excitation is studied in terms of film thickness determination. In the load-displacement curves a discontinuity is found during ultrasonic excitation. This discontinuity appears to be related to the carbon film thickness.