Fe-based amorphous magnetic powder, magnetic powder core with excellent high frequency properties and method of making them

Abstract

The present invention provides an amorphous alloy powder and magnetic powder cores exhibiting excellent high frequency properties and a method for making themof The composition of said alloy powder by atomic percentage satisfies the following formula: (Fe 1-x M x ) 100-a-b-c P a T b D c , wherein M represents at least one element of Co and Ni; T is over three elements selected from Al, C, B and Si, D is at least one element of Sn, Cr, Mn, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pt, Pd and Au; the subscripts x, a, b, and c satisfy the relationships 0.01≦x≦0.16, 8≦a≦15, 10≦b≦25 and 0.5≦c≦6. The said amorphous alloy powder is made by atomization method and a magnetic powder core comprises a molded article of mixture of the said alloy powder and an insulating material. A method of making the amorphous alloy powder core includes the steps of screening, insulating, compacting, annealing and spray painting.

1 . An amorphous alloy powder exhibiting excellent soft magnetic properties in high frequency range characterized by a composition in atomic percent of the following formula: (Fe 1-x M x ) 100-a-b-c P a T b D c , wherein M represents at least one element of Co and Ni; T is over three elements selected from Al, C, B and Si, D is at least one element selected from Sn, Cr, Mn, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pt, Pd and Au, the subscripts x, a, b, and c satisfy the relationships of 0.0≦x≦0.16, 8≦a≦15, 10≦b≦25 and 0.5≦c≦6.  
     
     
         2 . An amorphous alloy powder according to  claim 1 , the subscripts x, a, b, and c preferably satisfy the relationships of 0.01≦x≦0.12, 9≦a≦12, 10≦b≦23 and 1≦c≦5.  
     
     
         3 . An amorphous alloy powder according to  claim 1 , the subscripts a, b, and c preferably satisfy the relationship of 22≦(a+b+c)≦38.  
     
     
         4 . An amorphous alloy powder according to  claim 1 , characterized in that, the reduced glass transition temperature of said amorphous alloy powder T rg ≧0.53, wherein T rg =T g /T m , T g  represents glass transition temperature and T m  represents melting point of the alloy.  
     
     
         5 . An amorphous alloy powder according to  claim 1 , characterized in that, the supercooled liquid region of said amorphous alloy powder ΔT x ≧20K, wherein ΔT x =T x −T g , T x  represents crystallization temperature.  
     
     
         6 . An amorphous alloy powder according to  claim 1 , characterized in that the oxygen content of the powder in said amorphous alloy powder is below 4000 ppm.  
     
     
         7 . A method for making amorphous alloy powder exhibiting excellent soft magnetic properties in high frequency characterized in that the alloy powder with composition according to  claim 1  is made by atomization method, wherein said atomization maybe water atomization and/or gas atomization, while said gas atomization may be vacuum gas atomization, non-vacuum gas atomization, adjustable gas atomization or their combination.  
     
     
         8 . The method for making amorphous alloy powder according to  claim 7 , characterized in that the loose packed density of the powder ρ satisfies the relation: ρ>2.4 g/cm 3 .  
     
     
         9 . An amorphous magnetic powder core exhibiting excellent soft magnetic properties in high frequency range characterized by comprised the components by weight percentage as follows: 0.2%-7% of insulating agent, 0.01%-5% of adhesives, 0.01%-2% of lubricants and the rest is said amorphous alloy powder according to  claim 1 .  
     
     
         10 . The amorphous magnetic powder core according to  claim 9 , characterized in that said insulating agent is one or a combination selected from the following groups of substances: 
 Oxide powder selected from SiO 2 , CaO, Al 2 O 3  and TiO 2 ,    Salts selected from silicates and phosphates,    Mineral powder selected from mica powder and kaolinite, and    surface film produced by chemical deposition or self-oxidation.    
     
     
         11 . The amorphous magnetic powder core according to  claim 9 , characterized in that, said adhesives are organic adhesives and/or inorganic adhesives, wherein the organic adhesives are at least one selected from epoxy resins, the inorganic adhesives are at least one selected from phosphates.  
     
     
         12 . The amorphous magnetic powder core according to  claim 9 , characterized in that, said lubricants are one or a combination selected from stearates and talc powder.  
     
     
         13 . The amorphous magnetic powder core of amorphous alloy powder according to  claim 9 , characterized in that, the magnetic properties satisfy the requirements of one, several or their combination of the followings: 
 Magnetic permeability is no less than 35,    Quality factor Q is not less than 30 at 1 MHz,    Per unit of initial permeability is no less than 98% at 100 kHz, no less than 90% at 1 MHz;    Coercive force H c  corresponding with static magnetic hysteresis loop in maximum magnetic field of 2000 A/m is less than 70 A/m.    
     
     
         14 . A method for making an amorphous magnetic powder core exhibiting excellent soft magnetic properties in high frequency range characterized in that the process includes the following steps: 
 (a) Using said amorphous alloy powder according to  claim 1  and a required content of insulating agent, adhesives and lubricants, mixing themof and then drying them to obtain dry powder,    (b) Compacting said dried powder in a mold under a pressure of 500 MPa-3000 MPa to form a magnetic powder core,    (c) Annealing said molded magnetic powder core below the crystallization temperature of said amorphous alloy.    
     
     
         15 . The method for making amorphous magnetic powder core according to  claim 14 , characterized in that after step (c), preferably further including: (d) spray painting magnetic powder core and (e) testing the properties of magnetic powder core.  
     
     
         16 . The method for making amorphous magnetic powder core according to  claim 14 , characterized in that in step (c), the temperature for annealing said magnetic powder core is between (T x −100° C.) and T x , wherein T x  represents crystallization temperature; annealing time is from 5 minutes to 300 minutes, the atmosphere is one of vacuum, nitrogen and argon.  
     
     
         17 . The method for making amorphous magnetic powder core according to  claim 14 , characterized in that in step (c), the annealing temperature is preferably between (T x −70° C.) and (T x −20° C.), wherein T x  represents crystallization temperature of said alloy.  
     
     
         18 . The method for making amorphous magnetic powder core according to  claim 14 , characterized in that the magnetic properties of magnetic powder core obtained shall satisfy the requirements of at least one, or the combination of the following: 
 Magnetic permeability is no less than 35;    Quality factor Q is not less than 30 at 1 MHz;    Per unit initial permeability is not less than 98% at 100 kHz, not less than 90% or more at 1 MHz;    Coercive force H c  corresponding with static magnetic hysteresis loop in maximum magnetic field of 2000 A/m is less than 70 A/m.