Coating iron oxide particles for magnetic recording

Details Coating iron oxide particles for magnetic recording Coating iron oxide particles for magnetic recording

1979-03-19

1982-04-06

Silverman, Stanley S.

Coating processes

Magnetic base or coating

75 05AA, 75 05BA, 252 6256, 252 6257, 252 6258, 252 6259, 427214, 427215, 428694, 428900, B22F 102, G11B 562, C01G 4902

Patent

active

043235964

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.degree. to 900.degree. C.

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