METHOD FOR MANUFACTURING MAGNETIC MATERIAL, AND MAGNETIC MATERIAL POWDER WITH RUST PREVENTIVE LAYER THEREON AND BONDED MAGNET USING IT

摘要

PROBLEM TO BE SOLVED: To provide a method for producing excellent corrosion resistance by uniformly depositing a trace metal as a rust preventive coating film on the surface of a magnetic material and also to provide a method for improving, as compared with those obtained by the conventional technology, the rust preventive function and magnetic properties of the magnetic material by using the interdiffusion and reaction between the component in the vicinity of the surface of the magnetic material and the supplied highly activated metal. SOLUTION: The magnetic material powder composed of a magnetic alloy or a magnetic intermetallic compound and having grain boundaries of magnetic material phase in powder particles and a supply source (hereinafter referred to as rust preventive metal supply source) of a metallic component (hereinafter referred to as rust preventive metallic component) having a rust preventive action upon the magnetic material powder are introduced in a mixed state into a hermetically sealed vessel. Temperature is raised while maintaining a nonoxidizing atmosphere inside the hermetically sealed vessel in the above state, and the rust preventive metallic component is supplied from the metal supply source to the particle surface of the magnetic material powder. By this procedure, the rust preventive layer composed essentially of the rust preventive metallic component can be deposited on the particle surface and also on the region along the grain boundaries in the powder particles, by which the magnetic material powder with the rust preventive layer can be obtained.