Cobalt Oxalate Formation on Thin Film Magnetic Recording Media

We describe a new type of corrosion product that can form on the media surface during exposure to elevated temperature and humidity. An experimental carbon overcoated Co alloy media on glass substrates that exhibited high corrosion was exposed to elevated temperature and humidity at 65 degC/100% RH (non-condensing) for 48 hrs (RH/T exposure). Light scattering site density in sites per unit area was measured with an optical surface analyzer (OSA) on the exposed media after each processing step following vacuum deposition. Unlubricated media had the lowest scattering site density. Lubrication with 1 nm of Ztetraol 2000 increased the number of light scattering sites by 8x over the unlubricated media. The number of sites was 2x higher after burnishing.