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 . 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 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 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.   
     
     
         2 . The method for making amorphous magnetic powder core according to  claim 1 , further comprising after step (c), (d) spray painting magnetic powder core and (e) testing the properties of magnetic powder core. 
     
     
         3 . The method for making amorphous magnetic powder core according to  claim 1 , 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. 
     
     
         4 . The method for making amorphous magnetic powder core according to  claim 1 , characterized in that in step (c), the annealing temperature is between (T x -70° C.) and (T x -20° C.), wherein T x  represents crystallization temperature of said alloy. 
     
     
         5 . The method for making amorphous magnetic powder core according to  claim 1 , 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.