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.

Description

TECHNICAL FIELD[0001]Embodiments are directed to anodizing methods for growing an oxide layer on the surface of a nonferrous metal by an electrochemical process, such that the corrosion resistance property or abrasion resistance property of the nonferrous metal is improved. Particularly, the embodiments are directed to a power supply adapted to provide electrolyzer, where the anodizing process is conducted, with a pulse wave which includes Direct Current (DC) component and Alternating Current (AC) component. Further, the embodiments are directed to an anodizing method using the power supply and to the anodized layer grown by the anodizing method.BACKGROUND ART[0002]A nonferrous metal, such as Aluminum (Al), Magnesium (Mg), and Titanium (Ti), typically reacts with moisture contained in air with high reactivity such that a thin oxide layer is naturally formed on it. However, such a natural oxide layer is too thin or has too sparse structure to protect the nonferrous metal from abrasiv...

AI Technical Summary

Benefits of technology

"The invention provides a power supply for an anodizing process that provides an anodized layer with improved mechanical, electrical, and chemical properties compared to conventional methods. The apparatus includes a rectifying modulator unit, an AC modulating unit, a pulse wave synthesizing unit, and a control unit. The DC / AC-combined pulse wave generated by the apparatus has a peak voltage at a start point of each pulse wave that is controlled by the control unit. The anodized layer formed using the DC / AC-combined pulse wave has increased thickness and a unique cell structure. The invention also provides an anodized layer with improved mechanical, electrical, and chemical properties. The technical effects of the invention include improved anodized layer quality, increased thickness of the anodized layer, and improved mechanical, electrical, and chemical properties."

Problems solved by technology

However, such a natural oxide layer is too thin or has too sparse structure to protect the nonferrous metal from abrasive environment or corrosive environment.

However, when an oxide layer is formed by such chemical surface processes, the oxide layer is thin or has a low level of abrasion resistance, and therefore these chemical surface processes are not adequate for various applications.

However, according to the conventional anodizing methods, metal is dissolved simultaneously with the formation of oxide layer due to the reaction between the metal surface and electrolyte, such that the density of the oxide layer decreases and the mechanic property is deteriorated as the thickness of the oxide layer increases.

Therefore, it is difficult to grow the oxide layer over a certain thickness.

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