VERFAHREN ZUR HERSTELLUNG VON FERROMAGNETISCHEN LEGIERUNGSPULVERN

摘要

1348457 Ferromagnetic powder FUJI PHOTO FILM CO Ltd 16 Aug 1972 [19 Aug 1971] 38291/72 Heading C7D An acicular ferromagnetic alloy powder is produced by reducing salts of ferromagnetic metals in an aqueous solution in the presence of fine acicular powder and hypophosphite ions. The desired ferromagnetic alloy is based on Co, or Co-Ni with small additions of one or more of La, Ce, Nd, Sm, Al, S, Cr, Mn, Fe, Cu or Zn, and the salts used are the sulphate, chloride, acetate, formate, sulphamate, nitrate, hypophosphite, pyrophosphite or triethanolamine. The reducing hypophosphite ions are provided by hypophosphoric acid or a hypophosphite of an alkali metal or an alkaline earth metal. The fine acicular powder added to the bath may be α-or γ-FeO(OH), γ-Fe 2 O 3 , Fe 3 O 4 , CrO 2 , ZnO, V 2 O 5 , copper phthalocyamine, diatomaceous earth or attapulgite clay. Further additions include pH buffering agents, complexing agents, pH adjusting agents, and activating agents. The acicular powder produced may be used for recording tapes.