Method for anodizing aluminum alloy and power supply for anodizing aluminum alloy

Abstract

In a method for anodizing an aluminum alloy to form an anodic oxide film on a surface of the aluminum alloy using pulsed electric power, a short circuit is formed, after application of a positive pulse voltage, between an anode for anodic oxidation and a cathode for anodic oxidation for a short-circuit duration of not longer than 15 μs during non application of the pulse voltage. The pulsed electric power has a waveform having a cycle composed, in the order, of a pulse voltage application duration (T + ), a dead time (T d ) and a short-circuit duration (T s ). Then, no or almost no negative current is allowed to flow, and the film formation rate can be increased to improve productivity.

1 - 16 . (canceled)  
     
     
         17 . A method for anodizing an aluminum alloy component using pulsed electric power to form an anodic oxide film thereon, comprising the steps of: 
 providing a cathode in contact with an electrolyte solution,    placing the aluminum alloy component in the electrolyte solution as an anode,    applying repeating positive pulse voltages to the anode, and    forming a short circuit between the anode and the cathode for a short-circuit duration of 15 μs or less during each interval between two succeeding pulse voltages.    
     
     
         18 . A method for anodizing an aluminum alloy as recited in  claim 17 , wherein said short-circuit duration is not shorter than 1 μs and not longer than 15 μs.  
     
     
         19 . A method for anodizing an aluminum alloy as recited in  claim 17 , wherein said short-circuit duration is not shorter than 1 μs and not longer than 5 μs.  
     
     
         20 . A method for anodizing an aluminum alloy as recited in  claim 17 , wherein said pulsed electric power has a waveform having a cycle composed, in the order, of a pulse voltage application duration (T + ), a dead time (T d ) and a short-circuit duration (T s ).  
     
     
         21 . A method for anodizing an aluminum alloy as recited in  claim 17 , wherein said pulsed electric power has a frequency of 8 to 35 KHz.  
     
     
         22 . A method for anodizing an aluminum alloy as recited in  claim 17 , wherein said pulsed electric power has a frequency of 10 to 30 KHz.  
     
     
         23 . A method for anodizing an aluminum alloy as recited in  claim 20 , wherein said pulsed electric power has a frequency of 8 to 35 KHz.  
     
     
         24 . A method for anodizing an aluminum alloy as recited in  claim 20 , wherein said pulsed electric power has a frequency of 10 to 30 KHz.  
     
     
         25 . A power supply for a system for anodizing an aluminum alloy component using pulsed electric power to form an anodic oxide film thereon, wherein the aluminum alloy component is placed in the electrolyte solution together with a cathode, 
 said power supply comprising a first terminal electrically connected to said anode, a second terminal electrically connected to said cathode, and a pulsed electric power generating section configured to repeatedly apply repeating positive pulse voltages to said second terminal and to form a short circuit between said first and second terminals for a short-circuit duration of 15 μs or less during each interval between two positive pulse voltages.    
     
     
         26 . A power supply for anodizing an aluminum alloy as recited in  claim 25 , wherein said pulsed electric power generating section is configured to generate pulsed electric power which provides a short-circuit duration of not shorter than 1 μs and not longer than 15 μs.  
     
     
         27 . A power supply for anodizing an aluminum alloy as recited in  claim 25 , wherein said pulsed electric power generating section is configured to generate pulsed electric power in which the short-circuit duration is not shorter than 1 μs and not longer than 5 μs.  
     
     
         28 . A power supply for anodizing an aluminum alloy as recited in  claim 25 , wherein said pulsed electric power generating section is configured to generate pulsed electric power having a waveform composed, in the order, of a pulse voltage application duration (T + ), a dead time (T d ) and a short-circuit duration (T s ).  
     
     
         29 . A power supply for anodizing an aluminum alloy as recited in  claim 25 , wherein said pulsed electric power generating section is configured to generate pulsed electric power having a frequency of 8 to 35 KHz.  
     
     
         30 . A power supply for anodizing an aluminum alloy as recited in  claim 25 , wherein said pulsed electric power generating section generates pulsed electric power having a frequency of 10 to 30 KHz.  
     
     
         31 . A power supply for anodizing an aluminum alloy as recited in  claim 28 , wherein said pulsed electric power generating section is configured to generate pulsed electric power having a frequency of 8 to 35 KHz.  
     
     
         32 . A power supply for anodizing an aluminum alloy as recited in  claim 28 , wherein said pulsed electric power generating section is configured to generate pulsed electric power having a frequency of 10 to 30 KHz.