Patent ID: 6432377
Filing Date: 2002-08-13
Classification: B82Y,C01G,C01P,C09C,G11B,Y10S,Y10T

Abstract:
A method for producing particles for a non-magnetic undercoat layer of a magnetic recording medium, which comprises the steps of:dehydrating acicular goethite particles with the surfaces coated with a sintering-preventing agent to form acicular hematite particles, reducing the acicular hematite particles at a temperature of 250 to 600Â° C. under a reducing atmosphere to form acicular magnetite particles, washing with pure water and drying the acicular magnetite particles, oxidizing the acicular magnetite particles at a temperature of 650 to 850Â° C. under an oxidizing atmosphere, and washing with pure water and drying the resulting high-density acicular hematite particles.