US 4,988,755 A · Passivated rare earth magnet or magnetic material compositions

Abstract

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.

Claims96

Dependent claims

A passivated rare earth magnet composition, comprising:

particles of at least one rare earth magnet material,
a passivating agent, said passivating agent being an (A) oxidation resistant composition, or an (B) corrosion inhibitor, or mixtures of (A) and (B), or layers of (A) and (B) in any order, said passivating agent attached to and coating said at least one rare earth magnet material, the total amount of said passivating agent being 20 percent or less by weight based upon the total weight of said rare earth magnet material and said passivating agent, and
a binder adhering said coated particles of said at least one rare earth magnet material together and forming a passivated rare earth magnet composition, said binder comprising a thermoset polymer, a thermoplastic polymer, an elastomer, a reaction injection molding binder, or combinations thereof, the amount of said binder being from about 2 percent to about 60 percent by volume based upon the total volume of said rare earth magnetic material, said passivating agent, and said binder.

A passivated rare earth magnet composition, comprising;

particles of at least one rare earth magnet material;
the surface of said particles passivated by a localized concentration of a passivating agent, said passivating agent comprising an (A) oxidation resistant composition, or an (B) corrosion inhibitor, a mixture of (A) and (B), or layers of localized concentrations of (A) and (B) in any order about said rare earth magnet particles, the total amount of said passivating agent being 20 percent or less by weight based upon the total weight of said rare earth magnet material and said passivating agent, said (A) oxidation resistant composition comprising a (A1) ternary composition, or (Ax) binary composition, or both, said (Ay) ternary composition comprising
(1) an amino containing silane,
(2) an epoxy silane, and
(3) an epoxy resin, said (Ax) binary composition comprising
(1) an amino containing silane, and
(2) an epoxy silane or an epoxy resin, the amount of said binder being from about 2 percent to about 60 percent by volume based upon the total volume of said rare earth magnet material, said passivating agent, and said binder.

4 more elements

A sintered rare earth magnet article, comprising:

a sintered rare earth magnet,
the surface of said sintered rare earth magnet passivated by a localized concentration of a passivating agent, said passivating agent comprising an (A) oxidation resistant composition, or an (B) corrosion inhibitor, a mixture of (A) and (B), or layers of localized concentrations of (A) and (B) in any order about said rare earth magnet particles, the total amount of said passivating agent being 20 percent or less by weight based upon the total weight of said rare earth magnet and said passivating agent, said (A) oxidation resistant composition comprising a (Ay) ternary composition, or (Ax) binary composition, or both, said (Ay) ternary composition comprising
(1) an amino containing silane,
(2) an epoxy silane, and
(3) an epoxy resin,
said (Ax) binary composition comprising
(1) an amino containing silane, and
(2) an epoxy silane or an epoxy resin, and
said sintered article being free of a binder.

6 more elements

A passivated rare earth magnet-binder blend article, comprising:

a blend of a binder and rare earth magnet particles, said binder being a thermoplastic, a thermoset, an elastomer, or a reaction injection molded compound, said rare earth magnet particle containing at least one rare earth element having an atomic number of from 57 to 71, said blend encapsulated by a passivating agent, said passivating agent comprising an (A) oxidation resistant composition or an (B) corrosion inhibitor, or mixtures thereof, the amount of said passivating agent being 20 percent by weight or less based upon the total weight of said passivating agent, said binder, and said rare earth magnet particles.

A passivated rare earth magnet composition, comprising;

particles of at least one rare earth magnet material;
the surface of said particles passivated by a localized concentration of a plasma-treated passivating agent, said passivating agent comprising an (A) oxidation resistant composition, or an (B) corrosion inhibitor, a mixture of (A) and (B), or layers of localized concentrations of (A) and (B) in any order about said rare earth magnet particles, said (A) oxidation resistant composition comprising a (A1) ternary composition, or (Ax) binary composition, or both, said (Ay) ternary composition comprising
(1) an amino containing silane,
(2) an epoxy silane, and
(3) an epoxy resin, said (Ax) binary composition comprising
(1) an amino containing silane, and
(2) an epoxy silane or an epoxy resin,
the total amount of said plasma-treated passivating agent being 20 percent or less by weight based upon a total weight of said rare earth magnet material and said plasma-treated passivating agent, and a binder bonding said passivated particles together, and the amount of said binder being from about 2 percent to about 60 percent by volume based upon the total volume of said rare earth magnet material, said plasma-treated passivating agent, and said binder.

5 more elements

Dependencies are inferred from the claim text.

Passivated rare earth magnet or magnetic material compositions

Life of this patent

Passivated rare earth magnet or magnetic material compositions

Life of this patent

Abstract

Claims96