JPS5922797B2 - Anode parts for aluminum anodizing electrolytic treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for applying aluminum anodic oxidation electrolytic treatment, which mainly consists of alumite treatment and secondary electrolytic coloring, to aluminum or aluminum alloy materials. The present invention relates to an anode member such as a rack or clip that serves as an electrical contact for supporting and energizing the anode member.

As is well known, the secondary electrolytic coloring method for aluminum involves forming an anodic oxide film on the surface of an aluminum product through so-called alumite treatment, and then electrolytically treating it with an alternating current or an electric current similar to an alternating current in a metal salt-containing solution. This is a method of coloring the oxide film in a color unique to metal salts. Conventionally, aluminum products are supported and Aluminum or aluminum alloys are exclusively used as anode members for energizing products. In this way, when an anode member made of aluminum or aluminum alloy is used to perform a series of alumite treatment and secondary electrolytic coloring treatment on an aluminum product, the anode member surface is coated with the anode as well as the product surface during the alumite treatment. Since an oxide film is generated, the current flowing out from the anode member surface during the secondary electrolytic coloring treatment is of the same level as the product surface, and therefore the current flow is not locally concentrated on the anode member, so there is no effect on the product. Coloring can also be done uniformly.

By the way, in the alumite treatment prior to the secondary electrolytic coloring treatment, anode members made of aluminum or aluminum alloy have the following various problems due to their characteristics. In other words, in alumite treatment, as mentioned above, the anode member immersed in the electrolyte is anodized together with the product, and an anodic oxide film is generated on the surface, but at this time, the same amount of current flows from the surface of the anode member as the product surface. Because of the leakage, there is a problem of extremely large power loss. Further, as described above, the anodic oxide film formed on the surface of the anode member is non-conductive, so when the anode member is reused, it is necessary to dissolve and remove the film in order to obtain an electrical contact. In actual operation, the anodic acid J2 coating is dissolved and removed with an alkaline solution, or the coating on the surface of the anode member is removed with these treatment solutions, which also serves as alkali degreasing or chemical polishing, etc., performed as pretreatment for the product. In this way, with anode members made of aluminum, an anodic oxide film is repeatedly formed and removed each time the product is processed, and it gradually wears out, so it does not lose sufficient strength to support the product. Therefore, the aluminum anode member is a consumable material, and the cost of the anode member, which accounts for the operating cost, cannot be ignored. Further, as mentioned above, since a considerable amount of chemicals are used to remove the anodic oxide film, the cost required cannot be ignored. In this way, the anode member made of aluminum material poses no particular problem in the secondary electrolytic coloring process itself, but
There is a problem in the alumite treatment step, which is the preceding step, and therefore it is not inherently preferable as an anode member used in a series of these steps, that is, the aluminum anodizing electrolytic treatment step.

On the other hand, titanium anode members do not have the above-mentioned drawbacks when used for alumite treatment, and are therefore used in some areas despite being expensive, but there is a problem that they cannot be used for secondary electrolytic coloring treatment. .

In other words, titanium forms a dense anodic oxide film on its surface during direct current electrolysis during normal alumite treatment, and this anodic oxide film suppresses current flow from the surface of the titanium anode member, resulting in less power loss and Since the anodic oxide film is usually extremely thin (about several hundred λ), it is easily destroyed by the pressure of racking the product, so there is no need to dissolve and remove the anodic oxide film to obtain an electrical contact. It has various advantages for alumite processing, such as being able to be used repeatedly for a long period of time and having much higher strength than aluminum. However, during AC electrolysis, which is usually adopted in secondary electrolytic coloring treatment,
Despite the presence of the anodized film, a significant amount of current flows from the surface of the titanium anode member. For example, when the inventors of the present invention generated an anodic oxide film on aluminum and titanium materials by pretreatment under alumite treatment conditions, and then treated them under secondary electrolytic coloring conditions,
During the treatment under the secondary electrolytic coloring conditions, a current as shown in Table 1 below flowed out. Here, the pretreatment is 15% H2SO4
DC electrolysis was carried out for 20 minutes using the 20V constant voltage method as an electrolytic solution, and the secondary electrolytic coloring conditions were electrolyzed at AC 10V in a Ni salt bath at 20° C. with a pH of 4. As is clear from Table 1, when treated under secondary electrolytic coloring conditions, a current that is about 20 times larger is generated from the surface of the titanium material on which the anodic oxide film has been formed than on the aluminum material on which the anodized film has also been formed. leak.

Due to this phenomenon, when an aluminum product to be treated is latched onto a titanium anode member during secondary electrolytic coloring, current flows intensively from the titanium anode member, which causes the aluminum product to be treated to is not colored at all near the contact point with the anode member, and is 50 to 6
In the 0n range, the current density becomes non-uniform and uneven coloring occurs. Therefore, it is practically impossible to use a titanium anode member for the secondary electrolytic coloring treatment. In addition, in the above-mentioned test, assuming that the amount of current flowing out (A/DTrl) during treatment under electrolytic coloring conditions is the same or smaller than the amount of current flowing out of anodized aluminum material, in this case, It is clear that uneven coloring does not occur because the current does not concentrate on the anode member, and therefore, comparing the amount of current flow can be used as a guide for determining whether uneven coloring occurs. Due to the above-mentioned circumstances, an anode that can be commonly used for anodizing electrolytic treatment of aluminum products, that is, alumite treatment and subsequent secondary electrolytic coloring treatment, and that can eliminate the drawbacks of aluminum anode members in alumite treatment. There is a strong demand for the development of materials for parts.

However, the inventors of this invention have already filed a patent application in 1989-89.
As proposed in No. 637 and Japanese Patent Application No. 52-123171, Zircaloy alloy, which is used as a nuclear fuel cladding material, is optimal as an anode member for alumite treatment, and is equivalent to or better than titanium anode members. Furthermore, as proposed in Japanese Patent Application No. 53-8701, zirconium has also been found to have good properties close to those of Zircaloy alloys as an anode member for alumite treatment.

In other words, anode members made of zircaloy alloy or zirconium have significantly less power loss during alumite treatment than aluminum anode members, and can be used for a long period of time with less wear and tear, and they are also superior in these respects compared to titanium. They found that the material is excellent and does not suffer from breakage accidents due to material embrittlement that tends to occur with titanium. After further research, we found that zirconium alloys and zirconium, represented by zircaloy, have much better properties than titanium materials as anode materials for secondary electrolytic coloring, and that they can also be produced by normal alumite treatment. However, by applying appropriate treatment in advance to form a dense oxide film, it can be used as an anode member for secondary electrolytic coloring on a par with aluminum. They discovered that when used for electrolytic coloring, the uneven coloring that tends to occur at the rucking contact portions of products becomes imperceptible to the naked eye, leading to the creation of this invention.

That is, the anode member of the present invention is made of a zirconium alloy represented by Zircaloy or zirconium, and is preliminarily heated in an oxidizing atmosphere of 1 to 200%.
It is made by heating at a temperature of 850°C to form a dense oxide film on the surface, and due to the presence of such a dense oxide film, unlike the case of titanium anode members, it is difficult to color during secondary electrolytic coloring. 3 to suppress the current outflow and prevent uneven coloring of the product.

The anode member of the present invention will be explained in more detail below.

As mentioned above, the material of the anode member of the present invention is a zirconium alloy such as Zircaloy or metallic zirconium, and among these, Zircaloy is the most suitable. Further, Zircaloy is classified into 1 to 4 types depending on its composition range, and it goes without saying that any of the Zircaloys can be used as the anode member of the present invention. Further, the specific shape of the anode member of the present invention is arbitrary, and it may be made in the shape of a racking frame for hooking and holding the product to be treated, or it may be made in the shape of a clip for holding the product to be treated. As mentioned above, such an anode member is heated in an oxidizing atmosphere, for example, in air or in an oxygen stream, at temperatures of 200°C to 850°C.
Heat treatment is performed at a temperature of °C to form a dense oxide film on the surface. If the heating temperature is less than 200°C, the processing time will take a long time, which is not preferable. Also, the heating temperature is 85
If the temperature exceeds 0°C, there is a risk that the material will undergo annealing and softening, reducing the mechanical strength and springiness necessary for an anode member, and also precipitates will form in the material structure, causing deterioration of corrosion resistance. In addition, there is a problem that the economic cost required for the treatment increases.The heat treatment time is, for example, 30 at 500°C.As is clear from the test results shown in Table 2, In both Zircaloy alloy materials and zirconium materials, only a current of about 0.5 to 0.3 A/d flows out during secondary electrolytic coloring by alternating current electrolysis.In other words, secondary electrolytic coloring of titanium materials subjected to the same heat treatment It is much smaller than the amount of current flowing out in the secondary electrolytic coloring of anodized aluminum material. When an aluminum product is lathed onto a zirconium anode member and subjected to alumite treatment and secondary electrolytic coloring, the current during secondary electrolytic coloring will not be concentrated on the anode member, so titanium anode members are used. It is clear that uneven coloring does not occur as in the case.
Zircaloy alloy or zirconium anode members that have been heat-treated in advance to form a dense oxide film will not be as effective even if they are used for alumite treatment and secondary electrolytic coloring of aluminum products and this process is repeated multiple times. was found to persist.

As is clear from the above description, the anode member of the present invention can obtain properties equivalent to or better than those of an aluminum anode member in the anodizing electrolytic treatment of aluminum products, particularly in the secondary electrolytic coloring treatment thereof.

Furthermore, the anode member of the present invention has properties comparable to those of titanium anode members even in the alumite treatment that is normally performed prior to secondary electrolytic coloring treatment, and has mechanical strength that is equal to or higher than titanium anode members. . Therefore, the anode member of the present invention is extremely useful as an anode member used in the anodizing electrolytic treatment process of aluminum products, that is, the series of steps of alumite treatment and secondary electrolytic coloring treatment. It goes without saying that the anode member of the present invention may be used alone for alumite treatment of aluminum products.

Claims (1)

[Claims] 1 Constructed from a material made of zirconium or its alloy, and heated in advance to 200°C to 850°C in an oxidizing atmosphere.
An anode member for aluminum anodic oxidation electrolytic treatment that is heat-treated at a temperature of 100 to produce a dense oxide film on the surface.