| 摘要 |
PURPOSE:To maintain and improve magnetic characteristics and weatherability by incorporating ferromagnetic chromium dioxide deposited with cobalt or cobalt compd. on the surface into the titled medium. CONSTITUTION:This recording medium contains the ferromagnetic chromium dioxide deposited with the cobalt or cobalt compd. on the surface. The cobalt or the oxide thereof is deposited on the surface of chromium dioxide particles. Deposition of the oxide thereon is executed by mixing and agitating a cobalt salt and the chromium dioxide powder in water, adding an oxidizing agent such a ammonium nitrate thereto, blowing air to the mixture under heating and holding the mixture for several hours, then cooling and filtering the mixture. A plating method, vacuum deposition method, etc., are usable in the case of depositing the metal of the cobalt on the surface. The change rate of the characteristics of the recording medium is decreased even if the medium is rested for a long period of time at and under a high temp. and high humidity.
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