Process for producing ferromagnetic metallic particles
AssigneeHercules Incorporated
InventorJames E. French
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Abstract
Described is an improved process for producing acicular ferromagnetic metallic particles by the reduction of acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent. More specifically, the process concerns the improvement wherein the iron oxide or iron oxide hydrate particles are treated with a specified amount of a phosphorus compound and a compound of cobalt, nickel and/or copper prior to the reduction step.
Claims7
In the process for producing acicular ferromagnetic metallic particles suitable for magnetic recording media by reducing acicular particles of iron oxide or iron oxide hydrate with a gaseous reducing agent, the improvement which comprises treating said iron oxide or iron oxide hydrate particles prior to the reducing step with a water-soluble phosphorus-containing compound and with at least one compound of a metal selected from the group consisting of cobalt, nickel and copper under conditions to provide on the surface of the oxide particles a coating containing, based on iron, from 0.1 to 5 atomic % of phosphorus and at least 0.1 atomic % of said metal, the atomic ratio of said metal to phosphorus ranging from 0.5:1 to 10:1.
Dependencies are inferred from the claim text.