Rare earth element magnet

Abstract

A rare earth element magnet comprising molded magnetic powder containing at least one rare earth element, wherein a Fe rich phase covering a part or entire of the surface of particles of the magnetic powder and having a Fe atomic percentage larger than that of the magnetic powder, and an inorganic binder bonding the particles covered with the Fe rich phase.

1 . A rare earth element magnet comprising molded magnetic powder containing at least one rare earth element, wherein a Fe rich phase covering a part or entire of the surface of particles of the magnetic powder and having a Fe atomic percentage larger than that of the magnetic powder, and an inorganic binder bonding the particles covered with the Fe Rich phase. 
     
     
         2 . The rare earth magnet according to  claim 1 , wherein the Fe rich phase contains at least one rare earth element and oxygen. 
     
     
         3 . The rare earth element magnet according to  claim 1 , wherein the magnetic powder has a main phase of Nd 2 Fe 14 B, and the Fe rich phase is an oxide containing Nd and Fe, an atomic ratio of Fe to Nd+Fe being 50% or more. 
     
     
         4 . The rare earth element magnet according to  claim 1 , wherein the Fe rich phase is at least one member selected from the group consisting of Ge 17 Nd 2 , Nd 4.4 Fe 77.8 B 17.8 , NdFe 3 (BO 3 ) 4  and Fe. 
     
     
         5 . The rare earth element magnet according to  claim 1 , wherein the inorganic binder is SiO2 containing an alkoxy group. 
     
     
         6 . The rare earth element magnet according to  claim 1 , wherein a high resistance film having a thickness of 10 nm to 10 μm is formed between the surface of the particles of the magnetic powder and the inorganic binder. 
     
     
         7 . The rare earth element magnet according to  claim 6 , wherein the high resistance film comprises at least one oxyfluoride compound. 
     
     
         8 . The rare earth element magnet according to  claim 7 , wherein the oxyfluoride is a fluoride of rare earth element and/or fluoride of alkaline earth metal. 
     
     
         9 . A method of manufacturing rare earth element magnet comprising:
 compacting magnetic powder containing a rare earth element to form a molded magnet body;   heating the molded magnet body to form a Fe rich phase having a Fe atomic percentage higher than that of a mother phase constituted by the magnetic powder;   impregnating the molded magnet with a solution of a precursor of an inorganic oxide binder; and   Heating the molded magnet impregnated with the precursor solution to cure the precursor so as to form an inorganic binder.   
     
     
         10 . A method of manufacturing rare earth element magnet comprising:
 adding a treating solution containing a fluoride to magnetic powder containing rare earth element;   forming a fluoride coat film on the surface of the particles of the magnetic powder;   compacting the magnetic powder to form a molded magnet body;   heating the molded magnet body to form a Fe rich phase having a Fe atomic percentage higher than that of a mother phase constituted by the magnetic powder;   impregnating the molded magnet with a solution of a precursor of an inorganic oxide binder; and   heating the molded magnet impregnated with the precursor solution to cure the precursor so as to form an inorganic binder.   
     
     
         11 . The method of manufacturing rare earth element according to  claim 10 , wherein the treating solution containing a sol state fluoride contains swollen fluoride of rare earth element and/or alkaline earth element suspended in solvent whose main component is alcohol. 
     
     
         12 . The method of manufacturing rare earth element according to  claim 10 , wherein the fluoride of rare earth element and/or alkaline earth element has a particle size of 10 μm or less. 
     
     
         13 . The method of manufacturing rare earth element according to  claim 10 , wherein the alcohol is at least one of methyl alcohol, ethyl alcohol, n-propylalcohol and isopropyl alcohol.