Rare earth element sintered magnet and method for producing rare earth element sintered magnet
AssigneeShin-Etsu Chemical Co., Ltd.
InventorsKazuaki Sakaki, Masaki Kasashima, Ryuji Hamada, Takehisa Minowa
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Abstract
Hydrogen embrittlement is prevented in Sm2Co17-based magnets and R2Fe14B-based magnets by metal plating the magnet, then carrying out heat treatment, or by forming a metal oxide or metal nitride layer on the metal plating layer or directly on the magnet itself.
Claims12
A method of manufacturing rare-earth sintered magnets, characterized by subjecting an alloy composed of 20 to 30 wt % of a constituent R (R being samarium alone or at least 50 wt % samarium in combination with one or more other rare-earth element), 10 to 45 wt % iron, 1 to 10 wt % copper and 0.5 to 5 wt % zirconium, with the balance being cobalt and inadvertent impurities, to the steps of, in order, melting, casting, coarse size reduction, milling, molding in a magnetic field, sintering and aging so as to form a sintered magnet, surface machining the sintered magnet by cutting and/or grinding, metal plating the surface-machined magnet, then heat treating the metal-plated magnet at 80 to 850° C. for a period of from 10 minutes to 50 hours.
A rare-earth sintered magnet composed of 20 to 30 wt % of a constituent R (R being samarium alone or at least 50 wt % samarium in combination with one or more other rare-earth element), 10 to 45 wt % iron, 1 to 10 wt % copper and 0.5 to 5 wt % zirconium, with the balance being cobalt and inadvertent impurities, which rare-earth sintered magnet is characterized by having on a surface thereof, either directly or over an intervening metal-plating layer, a metal oxide layer and/or a metal nitride layer.
A method of manufacturing rare-earth sintered magnets, characterized by subjecting an alloy composed of 20 to 35 wt % of a constituent R (R being one or more rare-earth element selected from among neodymium, praseodymium, dysprosium, terbium and holmium), up to 15 wt % cobalt, 0.2 to 8 wt % boron, and up to 8 wt % of one or more element selected from among nickel, niobium, aluminum, titanium, zirconium, chromium, vanadium, manganese, molybdenum, silicon, tin, gallium, copper and zinc as an additive, with the balance being iron and inadvertent impurities, to the steps of, in order, melting, casting, coarse size reduction, milling, molding in a magnetic field, sintering and heat treatment to form a sintered magnet, surface machining the sintered magnet by cutting and/or grinding, metal plating the surface-machined magnet, then heat treating the metal-plated magnet at 80 to 700° C. for a period of from 10 minutes to 50 hours.
A rare-earth sintered magnet composed of 20 to 35 wt % of a constituent R (R being one or more rare-earth element selected from among neodymium, praseodymium, dysprosium, terbium and holmium), up to 15 wt % cobalt, 0.2 to 8 wt % boron, and up to 8 wt % of one or more element selected from among nickel, niobium, aluminum, titanium, zirconium, chromium, vanadium, manganese, molybdenum, silicon, tin, gallium, copper and zinc as an additive, with the balance being iron and inadvertent impurities, which rare-earth sintered magnet is characterized by having on a surface thereof, either directly or over n metal-plating layers (n being an integer such that n≧1), a metal oxide layer and/or a metal nitride layer.
Dependencies are inferred from the claim text.