Power supply for anodizing, anodizing method, and anodized film

Abstract

An anodizing method for growing an anodized layer on a surface of aluminum in electrolyte is disclosed. The method comprises applying a DC/AC-combined pulse wave between an anode and a cathode. The DC/AC-combined pulse wave is provided by combining a DC pulse wave with an AC wave, and has a peak voltage at a start point of each pulse. The grown anodized layer may be equal to or less than 300 μm in thickness, and the diameter of a cell in the anodized layer may range between 50 nm and 100 nm. The power supply used for anodizing may comprise a rectifying modulator unit, an AC modulating unit, a pulse wave synthesizing unit, and a control unit.

1 . An apparatus for providing a combined pulse wave for anodizing process, the apparatus comprising:
 a first pulse wave generation unit configured to provide a first pulse wave;   a second pulse wave generation unit configured to provide a second pulse wave; and   a pulse wave synthesizing unit configured to combine the first pulse wave and the second pulse wave.   
     
     
         2 . The apparatus according to  claim 1 , further comprising:
 A control unit configured to control an operation of the first pulse wave generation unit, the second pulse wave generation unit, and the pulse wave synthesizing unit.   
     
     
         3 . The apparatus according to  claim 1 , wherein,
 the first pulse wave is a first modulated DC pulse wave,   the first pulse wave generation unit is a first rectifying unit configured to provide the first modulated DC pulse wave by rectifying an AC voltage wave from an AC power supply to produce a first DC pulse wave and modulating a first and/or a first amplitude of the first DC pulse wave,   the second pulse wave is a second modulated DC pulse wave, and   the second pulse wave generation unit is a second rectifying unit configured to provide the second modulated DC pulse wave by rectifying the AC voltage wave from the AC power supply to produce a second DC pulse wave and modulating a second and/or a second amplitude of the second DC pulse wave.   
     
     
         4 . The apparatus according to  claim 3 , wherein,
 the first pulse wave generation unit operates independently from the second pulse wave generation unit.   
     
     
         5 . The apparatus according to  claim 3 , further comprising an AC modulating unit configured to provide an AC pulse wave by modulating a third period or a third amplitude of the AC voltage wave from the AC power supply, wherein,
 the pulse wave synthesizing unit is configured to combine the first modulated DC pulse wave, the second modulated DC pulse wave, and the AC pulse wave.   
     
     
         6 . The apparatus according to  claim 5 , wherein, at least one of the first pulse wave generation unit, the second pulse wave generation unit, and the AC modulating unit comprises a 600 kHz FET (Field Effect Transistor) and a capacitor with an electrostatic capacity of 1500 uF and a rated voltage of 400V. 
     
     
         7 . The apparatus according to  claim 5 , further comprising:
 a first on/off switch between the first rectifying unit and one of the AC power supply and the pulse wave synthesizing unit;   a second on/off switch between the second rectifying unit and one of the AC power supply and the pulse wave synthesizing unit; and   a third on/off switch between the AC modulating unit and one of the AC power supply and the pulse wave synthesizing unit.   
     
     
         8 . The apparatus according to  claim 1 , wherein,
 the first pulse wave is a first modulated DC pulse wave,   the first pulse wave generation unit is a first rectifying unit configured to provide the first modulated DC pulse wave by rectifying an AC voltage wave from an AC power supply to produce a first DC pulse wave and modulating a first and/or a first amplitude of the first DC pulse wave,   the second pulse wave is an AC pulse wave, and   the second pulse wave generation unit is an AC modulating unit configured to provide an AC pulse wave by modulating a third period or a third amplitude of the AC voltage wave from the AC power supply.   
     
     
         9 . An anodizing method for growing an anodized layer on a surface of an aluminum piece, the method comprising:
 providing an anode and a cathode in electrolyte, the anode comprising the aluminum piece; and   applying a pulse wave between the anode and the cathode,   wherein the pulse wave comprises a first modulated DC pulse wave component and an AC wave component, and the pulse wave has a peak voltage at a start point of each pulse.   
     
     
         10 . The anodizing method according to  claim 9 , wherein the pulse wave has a peak voltage at a start point of each pulse. 
     
     
         11 . An anodizing method according to  claim 9 , wherein the pulse wave comprises the first modulated DC pulse wave component, a second modulated DC pulse wave component, and the AC wave component. 
     
     
         12 . The anodizing method according to  claim 9 , wherein each pulse shape of the pulse wave is convex upward while the voltage level decreases from the voltage peak with time. 
     
     
         13 . The anodizing method according to  claim 9 , wherein negative voltage is applied between the anode and the cathode during the interval from an end point of a pulse to a start point of following pulse. 
     
     
         14 . The anodizing method according to  claim 11 , wherein the first modulated DC pulse wave component has different phase from the second modulated DC pulse wave component. 
     
     
         15 . The anodizing method according to  claim 9 , wherein a maximum voltage level or an average voltage level of each pulse of the pulse wave changes with time. 
     
     
         16 . The anodizing method according to  claim 9 , wherein a trajectory of the maximum voltage level or the average voltage level of each pulse of the pulse wave follows sine waveform. 
     
     
         17 . The anodizing method according to  claim 16 , wherein the trajectory is formed at least by,
 increasing a voltage level from an initial level to a predetermined first level,   maintaining the voltage level at the first level for a first predetermined time,   increasing the voltage from the first level to a second level, the second level being higher than the first level, and   maintaining the voltage level at the second level for a second predetermined time.   
     
     
         18 . The anodizing method according to  claim 9 , wherein at least one of a period with negative voltage of the pulse wave and a period with positive voltage of the pulse wave changes with time. 
     
     
         19 . An aluminum-containing piece with anodized layer formed by a process comprising a step of applying a pulse wave between an anode and a cathode, wherein,
 the anodized layer is formed on a surface of the aluminum containing, and a diameter of a cell in the anodized layer ranges between 50 nm and 100 nm, and a thickness of the anodized layer is between 20 μm and 300 μm, and   the pulse wave comprises a first modulated DC pulse wave component and an AC wave component, and the pulse wave has a peak voltage at a start point of each pulse.   
     
     
         20 . The anodizing layer according to  claim 19 , wherein the anodized layer is equal to or less than 300 μm in thickness.