Bayer Aktiengesellschaft

Gerhard Schroeder

Gunter Buxbaum

Franz Hund

Rolf Naumann

Heinrich-Christian Schopper

Bernd Stephan

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.

Ferromagnetic metal pigment essentially consisting of iron and a process

A finely divided magnetite pigment such as is used in magnetic tapes is stabilized against oxidation by contact with a heterocyclic nitrogen compound such as morpholine, triazole, piperazine or substitution products thereof. The heterocyclic compound can be applied as a solution or in vapor form.

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Krefeld, Germany

Gerhard Schroeder