Electric-Field-Assisted Dip-Coating for Ultra-Thin PFPE Lubricant Film on Magnetic Disks- Molecular Conformation Change by Electric Field -

Abstract

The mechanism responsible for the effects of electric fields on the lubricant dip-coating process was investigated by comparing the lubricant film conformations obtained when applying an electric field for different durations. A QA-40 solution was prepared for dip-coating a magnetic disk under two conditions. The lubricant film thickness and surface free energy obtained under the two conditions were compared. It was found that the molecular conformation was changed by the electric field resulting in more end-groups being adsorbed on the disk surface when the electric field is applied during the withdrawal of the disk from the solution than during the normal dip process. As a result, the surface free energy decreased. As a consequence of applying the electric field during dipping and withdrawing, the thickness of the QA-40 layer increased 1 - 3 Å.

Keywords

• tribology
• magnetic recording disk
• perfluoropolyther
• lubricant