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.

Abstract: A method for anodizing aluminum, wherein an object (29) made of aluminum or an aluminum alloy is anodized in an electrolytic solution (25), and thereby an anodized aluminum film is formed on a surface of the object (29), is provided. The electrolytic solution (25) is comprised of at least one acid selected from organic acids having two or more carboxylic groups, moves at an average speed of 15 cm/sec or less along at least an outer surface of the object (29). The anodization is performed under conditions that a temperature of the outer surface of the object (29) is 80° C. or less, and current density is in a range from 10 to 170 A/dm2.

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.

Abstract: A method for anodizing aluminum, wherein an object (29) made of aluminum or an aluminum alloy is anodized in an electrolytic solution (25), and thereby an anodized aluminum film is formed on a surface of the object (29), is provided. The electrolytic solution (25) is comprised of at least one acid selected from organic acids having two or more carboxylic groups, moves at an average speed of 15 cm/sec or less along at least an outer surface of the object (29). The anodization is performed under conditions that a temperature of the outer surface of the object (29) is 80° C. or less, and current density is in a range from 10 to 170 A/dm2.

Abstract: A spark plug includes a metallic housing, an insulator fixed in the metallic housing, a center electrode fixed in the insulator, a ground electrode opposed to the center electrode via a spark discharge gap, and a protective coat formed on the surfaces of a metallic housing and a gasket. The protective coat includes a galvanized film formed on the surfaces of the metallic housing and the gasket and a chromate film successively laminated on the galvanized film. The chromate film is hexavalent chromium-free and contains trivalent chromium as a major component. The chromate film has a film thickness not smaller than 0.05 ?m and not greater than 0.18 ?m, and the chromate film contains a metallic component which is robust against oxidation compared with zinc. Furthermore, the chromate film has a film hardness equal to or less than 1 GPa in the temperature range from a room temperature to 180° C.

Abstract: A spark plug includes a metallic housing, an insulator fixed in the metallic housing, a center electrode fixed in the insulator, a ground electrode opposed to the center electrode via a spark discharge gap, and a protective coat formed on the surfaces of a metallic housing and a gasket. The protective coat includes a galvanized film formed on the surfaces of the metallic housing and the gasket and a chromate film successively laminated on the galvanized film. The chromate film is hexavalent chromium-free and contains trivalent chromium as a major component. The chromate film has a film thickness not smaller than 0.05 ?m and not greater than 0.18 ?m, and the chromate film contains a metallic component which is robust against oxidation compared with zinc. Furthermore, the chromate film has a film hardness equal to or less than 1 GPa in the temperature range from a room temperature to 180° C.

Abstract: The present invention provides a method of forming a zinc coating that can form a chromate film, capable of withstanding hydrogen embrittlement-preventive treatment, by optimizing the conditions under which chromating is conducted.

Abstract: Disclosed are an electroless copper plating solution comprising a copper ion, a copper ion-complexing agent, a reducing agent and a pH-adjusting agent, the plating solution comprising a trialkanolmonoamine or a salt thereof as a complexing agent and accelerator in an amount giving a higher copper deposition speed than the copper deposition speed obtained when the trialkanolmonoamine or salt thereof is present in an amount sufficient to complex the copper ion but not enough to function as the accelerator, and 1.2.times.10.sup.-4 to 1.2.times.10.sup.-3 mole/l of an iron ion compound as a reaction initiator and/or 1.92.times.10.sup.-4 to 1.92.times.10.sup.

Abstract: Disclosed are an electroless copper plating solution comprising a copper ion, a copper ion-complexing agent, a reducing agent and a pH-adjusting agent, the plating solution comprising a trialkanolmonoamine or a salt thereof as a complexing agent and accelerator in an amount giving a higher copper deposition speed than the copper deposition speed obtained when the trialkanolmonoamine or salt thereof is present in an amount sufficient to complex the copper ion but not enough to function as the accelerator, and 1.2.times.10.sup.-4 to 1.2.times.10.sup.-3 mole/l of an iron ion compound as a reaction initiator and/or 1.92.times.10.sup.-4 to 1.92.times.10.sup.