Anodizing method of aluminum
AssigneeDenso Corporation
InventorsSeiji Amakusa, Tomoya Uchida
Life of this patent
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Abstract
In an anodizing method of aluminum, a tubular object made of aluminum or aluminum alloy is located between a pair of cathodes in an electrolysis solution, and a subsidiary cathode is inserted into the tubular object. The tubular object is anodized in the electrolysis solution to form an anodic oxide coating on an inner surface of the tubular object and on an outer surface of the tubular object. Accordingly, the anodic oxide coating can be formed easily not only on the outer surface of the tubular object but also on the inner surface of the tubular object. Therefore, a thickness difference of the anodic oxide coating between on the outer surface of the tubular object and on the inner surface of the tubular object can be reduced.
Claims27
A method for anodizing aluminum, comprising:
- locating a tubular object made of aluminum or aluminum alloy between a pair of cathodes in an electrolysis solution;
- inserting a subsidiary cathode into the tubular object;
- and
- anodizing the tubular object in the electrolysis solution to form an anodic oxide coating on an inner surface of the tubular object and on an outer surface of the tubular object;
- wherein
- the step of locating the tubular object includes sandwiching the tubular object on both ends of the tubular object in an axial direction of the tubular object and sandwiching the tubular object directly by a pair of holding portions which are electrically connected to an anode;
- an electric current density during the anodization is higher than or equal to 80 A/dm2, and
- an anodization time period for the anodization is less than or equal to 15 seconds.
A method for anodizing aluminum, comprising:
- locating a tubular object made of aluminum or aluminum alloy between a pair of cathodes in an electrolysis solution;
- inserting a subsidiary cathode into the tubular object;
- and
- anodizing the tubular object in the electrolysis solution to form an anodic oxide coating on an inner surface of the tubular object and on an outer surface of the tubular object;
- wherein
- a ratio of a length of the tubular object in an axial direction of the tubular object to an inner diameter of the tubular object is higher than or equal to 5;
- the step of locating the tubular object includes sandwiching the tubular object on both ends of the tubular object in an axial direction of the tubular object and sandwiching the tubular object directly by a pair of holding portions which are electrically connected to an anode;
- an electric current density during the anodization is higher than or equal to 80 A/dm2;
- and
- an anodization time period for the anodization is less than or equal to 15 seconds.
A method for anodizing aluminum, comprising:
- locating a tubular object made of aluminum or aluminum alloy between a pair of cathodes in an electrolysis solution;
- inserting a subsidiary cathode into the tubular object;
- and
- anodizing the tubular object in the electrolysis solution to form an anodic oxide coating on an inner surface of the tubular object and on an outer surface of the tubular object;
- wherein
- a ratio of a length of the tubular object in an axial direction of the tubular object to an inner diameter of the tubular object is higher than or equal to 10;
- the step of locating the tubular object includes sandwiching the tubular object on both ends of the tubular object in an axial direction of the tubular object and sandwiching the tubular object directly by a pair of holding portions which are electrically connected to an anode;
- an electric current density during the anodization is higher than or equal to 80 A/dm2;
- and
- an anodization time period for the anodization is less than or equal to 15 seconds.
Dependencies are inferred from the claim text.