Ferromagnetic metal pigment essentially consisting of iron and a process for its production

US4290799A · kind A · utility

Assignee

• BAYER HEALTHCARE LLC · DE

Inventors

• Gerhard Schroeder · Krefeld, DE
• Gunter Buxbaum · Krefeld, DE
• Franz Hund · Krefeld, DE
• Heinrich-Christian Schopper · Krefeld, DE
• Rolf Naumann · Krefeld, DE

Key dates

• Filing date: Feb 25, 1980
• Grant date: Sep 22, 1981
• Expiry date: Feb 25, 2000

Classification

• Technology area (CPC G): Physics
• CPC primary: G11B5/70615
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A metal powder, suitable for magnetic recording, consisting essentially of iron, the individual particles being acicular and containing on average no more then 5 pores and consisting on average of no more than 2 metal cores is produced by precipitating and oxidizing an aqueous iron-(II)-salt solution to produce finely divided acicular iron-(III)-oxide-hydroxide, stabilizing it as by treatment with cadmium, lead, calcium, magnesium, zinc, aluminum, chromium, tungsten, a phosphorus oxide and/or a boron oxide, converting it into ferromagnetic iron oxide of low pore content, and reducing it to metallic iron with a gaseous reducing agent at about 300.degree. to 600.degree. C.