Properties of Evaporated Phosphazene Lubricants on a Carbon Surface

A combination of a lubricant layer and carbon layer is generally used to provide wear and corrosion protection to the magnetic layer in a magnetic medium. Typically, the carbon layer has a diamond-like structure doped with hydrogen and/or nitrogen. After the vacuum coating is applied, the coated substrate is removed from the vacuum system and immersed in a dilute lubricant solution. The substrate is slowly withdrawn from the lubricant solution or placed in a tank from which the solution is drained. Lubricant thicknesses are controlled by varying the solution concentration and/or the drain rate. In this report, we will present results of evaporated X-1P as a single component lubricant instead of as an additive as has been used in the disk industry. The evaporation process has been chosen to substitute for the well known lubricant dipping technique as the deposition technique to coat the lubricant due to the following reasons: (i) eliminate solvent, (ii) improved control of the lubricant /carbon interface by reducing exposure to water and oxygen prior to lubricant deposition, (iii) combination of lubricant and carbon coating in one vacuum system, (iv) improve yield using shorter process time and (v) phosphazene molecules have low vapor pressure, high thermal stability and narrow molecular weight distribution.