Patent · US Expired

Agglomerated ferromagnetic iron particles

US4470844A · kind A · utility

7Cited by

7References

4Claims

0Family size

Assignee

BAYER HEALTHCARE LLC · DE

Inventors

Jakob Rademachers · Krefeld, DE
Rolf Naumann · Krefeld, DE
Hans-Peter Biermann · Krefeld, DE
Gunter Buxbaum · Krefeld, DE
Wolfgang Rambold · Krefeld, DE

Key dates

Filing date	Nov 25, 1981
Grant date	Sep 11, 1984
Priority date	—
Expiry date	Nov 25, 2001

Classification

Technology area (CPC H)Electricity
CPC primaryH01F1/061
WIPO fieldElectrical machinery, apparatus, energy
WIPO sectorElectrical engineering

Abstract

Spherical agglomerates of surface-stabilized primary particles substantially consisting of iron, having a BET surface of about 5 to 50 m.sup.2 /g, measured on the agglomerate, in non-pyrophoric form and having a bulk density of about 0.5 to 2.0 kg/l and an agglomerate diameter of about 0.5 to 10 mm are produced by PA1 (a) reducing in dry phase particles consisting essentially of iron oxide, PA1 (b) intensively dispersing the particles in liquid phase, PA1 (c) coating the particles with an inorganic and/or organic coating optionally containing corrosion inhibitors, PA1 (d) separating the particles from the liquid phase by evaporating the volatile components with a continuously rotating and simultaneously tumbling movement, and PA1 (e) subjecting the resulting granulates to a thermal treatment. The particles are especially useful for the production of magnetic recording media.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.