Molecular weight effect on surface morphology of bonded lubricant layer for hard disk-replica-AFM observation

Atomic Force Microscope (AFM) imaging with plasma-polymerized-carbon (PPC) replication allows us to observe the lubricating layer on hard disks and analyze the effect of Molecular Weight (MW) of the lubricating liquid on the surface shape. Larger molecular weight caused; thicker bonded lubricant layer; smoother coating on carbon surface; increase in aggregated lubricant clusters; and higher clusters. When the carbon overcoat holds a larger amount of bonded lubricant, the lubricant coverage of the carbon surface widens for the surface to withstand repeated contact-start-stop operations. We conclude that saturating the carbon surface with bonded lubricant prevents direct contact between the head and the disk.