Hexagonal system ferrite magnetic powder for magnetic recording

Abstract

Abstract PURPOSE:To reduce the temperature variation of coercive force by a method wherein a specific quantity of Fe<2+> is contained in the magnetic powder of substitution type hexagonal ferrite. CONSTITUTION:Fe<3+> is converted to Fe<2+> by performing an annealing in a reducing atmosphere on the hexagonal barium whereon a Co-Ti substitution is performed. Said reducing atmosphere is formed using hydrogen gas, forming gas containing H2 or carbon monoxide gas and the like. The desired temperature range of annealing is 350-500 deg.C or below. The annealing period is made longer at low temperature and it is made shorter at high temperature. The annealing is performed for 1hr at the temperature range of 350-500 deg.C or below. The barium ferrite formed as above contains Fe<2+> of 0.1-16wt%. The Hc of Ba ferrite at room temperature before annealing is 840Oe, and the Hc at 100 deg.C is 1,280Oe. The temperature characteristics of the coercive force of the magnetic powder can be improved effectively by the simple constitution as above- mentioned.

Inventors

• 👤 Osamu Kubo
• 👤 修 久保
• 👤 Tadashi Ido
• 👤 井戸　忠
• 👤 Tatsumi Maeda
• 👤 前田　辰己
• 👤 Tsutomu Nomura
• 👤 野村　力

Bibliographic Details