The B. F. Goodrich Company

E Douglas Dickens, Jr

Anthony M Mazany

Oxidation of fully dense rare earth magnets is reduced when a passivating agent such as an oxidation resistant composition or corrosion inhibitor or combinations thereof, is coated thereon. The oxidation resistant composition is a binary or a ternary composition made from (a) at least one amino containing silane compound such as an aminosilane or a polyaminosilane, or (b) at least one epoxy resin, or (c) an epoxy silane compound, or all three such compounds. The oxidation resistant composition, the corrosion inhibitor, or combinations thereof, passivate the surface of the fully dense rare earth magnets and generally form a highly concentrated coating on the surface thereof. Antidegradants are optionally utilized to improve the performance of the fully dense rare earth magnets with regard to improved oxidation resistant properties and generally include organic phosphorus compounds and/or alcohols. One or more layers of the passivating agent and/or one or more layers of the antidegradant are applied to the fully dense magnet which can be in the form of an end product, an article, or any element or component thereof, and which is desirably substantially free of a binder. Such protective fully dense magnets have excellent high temperature oxidation resistance, corrosion resistance, degradation resistance, and the like.

Passivated rare earth magnet or magnetic material compositions

Oxidation of particles of rare earth magnetic materials is greatly reduced when a passivating agent such as an oxidation resistant composition or corrosion inhibitor or combinations thereof, is coated thereon. The oxidation resistant composition is a binary or a ternary composition made from (a) at least one amino containing silane compound such as an aminosilane or a polyaminosilane, or (b) at least one epoxy resin, or (c) an epoxy silane compound, or all three such compounds. The oxidation resistant composition, the corrosion inhibitor, or combinations thereof, passivate the surface of the magnetic particles and generally form a highly concentrated coating on the surface thereof. Antidegradants are optionally utilized to improve the performance of the rare earth magnet composition with regard to improved oxidation resistant properties and generally include organic phosphorous compounds and/or alcohols. Various binders such as an elastomer, a thermoplastic, a thermoset, or a polymer generally formed by reaction based injection molding (RIM), act to adhere the various particles together and form an oxidation resistant rare earth magnet composition. Products can be made by various polymer processing techniques such as extrusion, calendering, injection molding, compression molding, and the like. The passivated rare earth magnetic materials of the present invention have excellent high temperature (e.g. 150.degree. C.) oxidation resistance, and excellent corrosion resistance.

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Richfield, OH, United States of America

E Douglas Dickens, Jr