Functional effects of carbon-coated iron metal particles for magnetic recording media

Magnetic particles with finer size, higher coercive force, and lower electrical resistance are required to produce better magnetic recording media. Metal has become one of the most suitable materials for high-density magnetic recording media; however metal particles are chemically unstable and their magnetic properties such as coercive force and saturation magnetization are easily ruined. We have tried carbon coating using a chemical agent to aid the carbon to adhere to the surface of metal particles. The carbon-coated particles become chemically stable and their oxidation is gradual enough to extinguish the ignition point. Magnetic tapes prepared using the carbon-coated metal particles in the recording layer exhibit improvements in both electrical resistance and orientation properties. A decrease in the electrical resistance of about two orders of magnitude relative to conventionally prepared tapes is achieved when about 10% of the particle weight is carbon black. The squareness and orientation ratio are also raised and viscosity is lowered because the dispersibility of these particles in magnetic lacquer is better than that of the uncoated metal particles. Transmission electron microscopy photographs indicate that all of the carbon black is bound to the surface of the metal particles. (C) 2002 The Electrochemical Society.