SURFACE TREATMENT OF MAGNETIC POWDER FOR ND-FE-B-BASED ANISOTROPIC BONDED MAGNET

摘要

PURPOSE:To easily and stably obtain an anisotropic magnetic powder whose resistance to oxidation is excellent by a method wherein its surface is coated with a silane-based organic metal compound of a specific ratio. CONSTITUTION:Anisotropy is endowed by warm-processing an Nd-Fe-B-based superquenched thin piece; after that, this thin piece is pulverized and magnetic powder to be used for an anisotropic bonded magnet is obtained; the surface of the magnetic powder of 100 parts by weight (pts.wt.) is coated with a silane- based organic metal compound of 0.05-5.00pts.wt. One pts.wt. of the silane-based organic metal compound and two pts.wt. of an ethanol water-soluble solution (a mixture in a volume ratio of water to ethanol in 1:9) are added to 100pts.wt. of the Nd-Fe-B-based anisotropic magnetic powder which has been pulverized to a particle diameter of, e.g., 500mum or less; they are mixed sufficiently by using a mixer. Then, if this magnetic powder is dried in an atmosphere of nitrogen at 80 deg.C for two hours, the anisotropic magnetic powder whose surface has been treated with the silane-based organic metal compound is obtained.