| 摘要 |
PURPOSE:To prevent high purity gas from lowering its purity and from being contaminated, by subjecting the inner surface of a cylindrical body made of aluminum, to anodize treatment to form an anodize coating film. CONSTITUTION:After an aluminum pipe is produced by an extrusion process, one end opening of the pipe is closed while the other end opening of the pipe is subjected to a press forming process such as spinning or the like to form a port section, thereby an aluminum cylindrical body is produced. The inner surface of the cylindrical body is subjected to anodize treatment of a. c. electrolysis in an electrolyte composed of (COOH)2 at a voltage of 50V and at a current density of about 2.5A/dm<2> to form an oxalic acid oxidation anodize coating film. Thereby it is possible to prevent high purity gas from lowering its purity and from being contaminated caused by products which are produced as a result of corrosion, in the cylindrical body, resulted from reaction of high purity gas with the cylindrical body. |
