Title:
IRON OXIDE GRAIN FOR RECORDING MAGNETISM AND ITS PREPARATION
Document Type and Number:
Japanese Patent JPS54137696
Kind Code:
A
Abstract:
In the preparation of highly orientatable needle-shaped ferrimagnetic iron oxide particles by the reduction and reoxidation of needle-shaped particles of hydrated oxide of iron which have been surface treated against sintering the improvement which comprises effecting the surface treatment by applying to the particles of hydrated oxide of iron one layer of oxygen-containing anions and a further layer of polyvalent cations, each layer weighing about 0.02 to 2% by weight of the particle. Advantageously, the polyvalent cation-containing layer is applied between two oxygen-containing anion layers, the oxygen-containing anions used are selected from the group consisting of silicate, phosphate, borate, vanadate, molybdate and tungstate, the polyvalent cations used are selected from the group consisting of aluminum, chromium, manganese, iron and gallium, each layer weighs about 0.1 to 1% of the weight of the particles and before the reduction and reoxidation the surface treated particles of hydrated oxide of iron are tempered at a temperature of about 600 DEG to 900 DEG C.
Inventors:
GUNTAA BUTSUKUSUBAUMU
INGO FURUGUMATSUHAA
FURANTSU FUNTO
FUORUKAA HAANKAMU
PEETAA BODEITSUSHIYU
INGO FURUGUMATSUHAA
FURANTSU FUNTO
FUORUKAA HAANKAMU
PEETAA BODEITSUSHIYU
Application Number:
JP4261079A
Publication Date:
October 25, 1979
Filing Date:
April 10, 1979
Export Citation:
Assignee:
BAYER AG
International Classes:
C01G49/00; C01G49/02; C01G49/06; C09C1/24; G11B5/712; C09D5/23; C09D7/12; C09D9/04; G11B5/70; G11B5/706; H01F1/11; (IPC1-7): C01G49/02; G11B5/70; H01F1/11