Metals with inhomogeneous magnetic field strength

Abstract

Metal nanowires were formed on electroformed magnetic metals when porous templates were prepared by anodizing aluminum or its alloys. The aspect ratio of the anodic oxide pores was controlled by the electrolyte composition, electrolytic conditions, and the subsequent widen-treatment of the anodized pores. Because of the magnetic field strength of the electroformed nanowires increases with increasing the aspect ratio, the electroformed metal with higher aspect-ratio nanowires has a greater magnetic field strength. Accordingly, metals with inhomogeneous magnetic field strength were obtained.

1 . A method for manufacturing electroformed metals with inhomogeneous magnetic field strength, wherein the electroformed metals are made by using ordered hexagonal porous anodic oxide of aluminum or its alloys generated from anodization in acidic electrolyte as templates.  
     
     
         2 . The method as claimed in  claim 1 , wherein the electroformed metals are magnetic iron, cobalt, nickel, gadolinium, dysprosium, samarium or their alloys.  
     
     
         3 . The method as claimed in  claim 1 , wherein the ordered hexagonal porous anodic oxide is able to be electroformed with other metals subsequently after part or whole of pores thereof being electroformed with magnetic iron, cobalt, nickel, gadolinium, dysprosium, samarium or their alloys.  
     
     
         4 . The method as claimed in  claim 1 , wherein the ordered hexagonal porous anodic oxide is on whole of or selected area of surface of the aluminum or its alloys.  
     
     
         5 . The method as claimed in  claim 1 , wherein the acidic electrolyte is sulfuric acid, oxalic acid, phosphoric acid or mixtures of above acids.  
     
     
         6 . The method as claimed in  claim 1 , wherein current for anodizing is direct current or alternating current.  
     
     
         7 . The method as claimed in  claim 1 , wherein the aluminum alloy for anodizing includes Al—Mg alloy, Al—Mg—Si alloy, Al—Zn—Mg alloys, Al—Mn alloy, Al—Mn—Cr alloy and Al—Mg—Si—Cu—Cr alloy.  
     
     
         8 . The method as claimed in  claim 1 , wherein aspect-ratio of the hexagonal porous anodic oxide obtained from anodization is controlled by composition of acidic electrolyte, voltage and current for anodizing, temperature of anodizing solution, processing time of anodizing and conditions of pore-widening.