Thin protective film for magnetic discs

A thin film of hexamethyldisiloxane, C₆H₁₈Si ₂O, is deposited on a magnetic disk to protect its thin-metal-film medium. The comparison of the overcoat is analyzed using electron-spectroscopy chemical analysis (ESCA) and Auger profiling. It is found that upon polymerization, carbon, silicon, and oxygen are uniformly distributed in the film except in the near-surface layer of 3-5-nm thickness, where the carbon content is increased. Despite the differences in protective film thickness the value of the dynamic friction coefficient is practically constant (0.13-0.15), whereas the measured values of the static friction coefficient μ_s vary from 0.16 to 0.75. The value of μ_s and the composition of the film surface layer are well correlated; the lowest value of μ_s corresponds to the highest carbon content in the surface layer