JPS6015435B2 - Method for manufacturing aluminum core electrode rod with titanium coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the method of manufacturing an aluminum core electrode shank having a titanium coating as a cathode or anode of an electrolyzer.

Traditionally, single metals such as lead, copper, iron, and aluminum have been used as the cathode or anode of electrolyzers, but in recent years, corrosion-resistant titanium has been used to improve corrosion resistance or prevent pollution. A trend is seen in which a coated aluminum core material is used.

In this case, the titanium coating method is to explosively bond a titanium pipe to the lateral surface of the copper round and then form it by rolling or drawing, or insert an aluminum round rod into the titanium pipe and then crimping it by drawing, etc. The former method requires special processing and is expensive, while the latter method is merely crimping, so no metallurgical bond can be obtained between aluminum and titanium.

If a metallurgical bond cannot be obtained, when performing various plastic workings for electrodes or welding the outer titanium, voids may be created between the copper or aluminum core material and the outer titanium coating, or large numbers of holes may be formed in the titanium coating. Produces sustenance.

As a result, its properties as an electrode rod are seriously impaired, and the purpose of this pot, which uses highly conductive copper or aluminum as the core material, is lost. Therefore, in the present invention, after a titanium tube is pressure-fixed to an aluminum core as a core material by swaging or seal rolling processing, a simple diffusion heat treatment is added to bond the aluminum core material and the titanium coating material. This is an attempt to create a stronger bond between the two.

That is, the present invention prepares a titanium tube that has been pickled with fluoronitric acid, washed and dried with water, and an aluminum rod that has been cleaned with acid or alkali, washed and dried with water, and inserts the aluminum rod into the inner hole of the thus purified titanium tube. Then, the titanium tube is shrunk by swaging or roll rolling so that its cross-sectional area reduction rate is 30 to 60% at room temperature, and the titanium tube is fixed to an aluminum rod under pressure. Ti-AI at the interface between
It is an object of the present invention to provide a method for manufacturing an aluminum core electrode shank having a titanium coating, which is characterized by performing a diffusion heat treatment sufficient to form an alloy layer.

In the present invention, pretreatment of the titanium tube and the aluminum rod is a necessary condition to remove impurities such as oil and fat attached to the respective surfaces and strong oxides formed on the surfaces, and to obtain an active surface. The reason why the diffusion heat treatment can proceed at a temperature below the melting point of aluminum and form a Ti-AI alloy layer is that both the bonding surfaces of the two are activated and that both the titanium and aluminum are swathed in the previous process. Pressed by rolling or roll rolling,
This is because a metallurgical bonding state is obtained due to mutual friction, albeit slightly, and the diffusion heat treatment in this state promotes the formation of a metallurgical bonding layer, forming a uniform and stable bonding layer. be.

The Ti-N alloy layer formed at this time is a diffusion alloy layer formed between ordinary aluminum and a different metal, such as a Fe-N alloy layer.
It is not a hard layer like the N alloy layer (Fe2AI5, FeA13) or the Cu-AI alloy layer (Ri2, So2), the thickness of the layer is 5 peaks or less, and the microstructure has plastic deformability. Therefore, even after this alloy layer is formed, it can be easily bent, compressed and deformed, and cracks and peeling of the alloy layer do not occur. It also withstands sudden thermal shock when welding other titanium materials to the titanium coating, and the thermal shock applied to the titanium coating is significantly reduced due to the good heat conduction of the aluminum core material due to the metallurgical bond between Ti and AI. This makes it easier to perform arc welding and other welding operations. In this way, the Tj-AI alloy layer
Because of its excellent performance, which is significantly different from that of Ti and Cu-N, it is possible to form a Ti single-needle alloy layer to obtain electrode fins that are metallurgically bonded firmly.

In carrying out the present invention, when compressing an aluminum rod by swaging or roll rolling after inserting it into a titanium tube, the appropriate reduction percentage is 30 to 60% in terms of its cross-sectional area, and if it is less than 30%, the diffusion will be carried out later. Even in heat treatment, the formation of an alloy layer is insufficient, and the heat treatment requires a long time. On the other hand, if the reduction exceeds 60%, the elongation rate of titanium decreases and there is a risk of cracking. The diffusion heat treatment temperature is a temperature below the melting point of aluminum and aluminum alloys, up to the phase line, but this is closely related to the treatment time, with high temperature for a short time and low temperature for a long time. Usually 60 for pure aluminum
0~650qo x 2 hours, 540℃~590 in case of 1 day
℃×2 hours. If necessary, heat treatment for pre-phosphorus dulling of titanium tubes, pressure compression oval molding to increase the strength of the finished product, titanium coating on the outer periphery, welding of titanium with other titanium materials, and end sealing of the finished product. Welding of titanium chips can be carried out as appropriate. Example 1 A pure titanium tube with a wall thickness of 0.5 mm and an outer recessed proboscis was degreased, then pickled with hydrofluoric acid (18 parts of hydrofluoric acid and 5 parts of nitric acid), washed with water, and dried.

Next is the outer diameter? After degreasing 99.5% aluminum twill made of No. 17 willow, it was pickled with fluoronitric acid from the same machine, washed with water, dried, and inserted into the inner hole of the titanium tube. This was made into a striped tube using a swaging machine at room temperature, and the outer diameter was set to ◇13 by applying 02 ribs three times each time. Next, this is heated to 620 qo in a continuous heat treatment furnace in an atmospheric atmosphere.
After heating for 3 hours, it was taken out and allowed to cool in the air. As a result, mutual diffusion and the formation of a slight alloy layer were observed between aluminum and titanium, indicating a complete metallurgical bond over the entire circumference. Example 2 A pure titanium tube with a wall thickness of 0.5 willow and 15 ribs on the outside was pretreated in the same manner as in Example 1.

Next, after degreasing the 1st aluminum alloy of the 13th yanagi
The sample was pickled with 0% hydrochloric acid, washed with water and dried, and then inserted into the inner hole of the titanium tube. This was pressurized by roll rolling, and the outer diameter was contracted five times on each side to form an outer recess of one end. Next, it was heated in the same manner as in Example 1 for 580 qo x 2 hours. In the case of aluminum alloy, the diffusion tendency similar to that of pure aluminum and Ti
- Formation of an AI alloy layer was obtained. Next, the results of property tests using samples obtained in this example will be explained. {1} Tensile rupture test Figures 1 and 2 show the fracture situation (magnification 1:1/3)
and (1:1 magnification) micrograph.

The former was obtained by subjecting the sample prepared in Example 1 to tensile fracture, and the fracture surface exhibits the same situation as that of a single material. The latter is the tensile fracture state of a composite material made of a titanium tube with an outer diameter of 13 ribs (wall thickness 0.5 willow) and an aluminum core made of 12 willows with a small diameter (wall thickness 0.5 willow) without metallurgical bonding. This shows a situation in which the specimen extends independently and breaks. ■ Bending test The electrical performance of the composite electrode was measured when it was deformed by external force during molding after completion or during use.

Table 1 shows the change in electrical resistance value (MU) between the conventional product and the product of the present invention before and after bending as shown in FIG. 3, and it is possible to see a remarkable difference. As described above, the present invention has excellent electrical properties by attaching a titanium tube to an aluminum rod as a core material under pressure by swaging or rolling, and then adding a simple diffusion heat treatment process.
Since a highly reliable electrode rod can be obtained, the practical effect is extremely large.

Table 1 Comparison of electrical resistance values of conventional products and the present invention (unit: ○)

[Brief explanation of the drawing]

Figure 1 shows the tensile cross section of the present invention for the sample prepared in Example 1, Figure 2 shows the tensile fracture cross section of a conventional product without metallurgical bonding, and Figure 3 shows the electrical resistance measurement test piece after bending. show. Figure 1 Figure 2: Tensile fracture surface of the present invention Figure 2: 50 plates between A and B of the conventional product (Ti surface) 50 plates between A and B (Ti surface)

Claims (1)

[Claims] 1 Prepare a titanium tube that has been pickled with fluoronitric acid, washed and dried with water, and an aluminum rod that has been cleaned with acid or alkali, washed and dried with water, insert the aluminum rod into the inner hole of the titanium tube, and check the area reduction rate at room temperature. After applying pressure and fixing the titanium tube to the aluminum rod by swaging or rolling so that the ratio of 1. A method for manufacturing an aluminum core electrode rod having a titanium coating, the method comprising performing a diffusion heat treatment sufficient to form a titanium-coated aluminum core electrode rod.