Copper clad aluminum wire refers to the wire with aluminum core wire as the main body and coated with a certain proportion of copper layer on the outside, which can be used as the conductor for coaxial cable and the conductor of wire and cable in electrical equipment. The specific gravity of aluminum wire is small, but its welding performance is not good, so the aluminum wire is wrapped with copper layer, which can not only take advantage of the small specific gravity of aluminum, but also improve the welding performance. It is applicable to the electric power and electrical industry, and the category and grade are international and domestic.

Because the main function of this kind of wire is to transmit signals, the current flowing through it is very small. However, since the conductivity of aluminum is only 2/3 of that of copper, the national standard stipulates that all wires and cables used to transmit electric energy must use non metallized or metallized annealed copper wires as conductors, and it is forbidden to use aluminum wires (including copper clad aluminum wires) as conductors.

In order to prevent the electrochemical corrosion of the end of copper-clad aluminum wire, the best way is to isolate the end from the atmosphere. At present, there are two methods to prevent the corrosion of copper-clad aluminum wire:

1. Electroplating method of preventing corrosion of copper-clad aluminum wire: plating a layer of copper at the joint of copper-clad aluminum wire, but it takes too much time (40 minutes). However, the application in enterprises producing copper clad aluminum wire is not a big problem, because many joints can be electroplated at the same time. Copper plating on the surface of aluminum is very difficult.

2. The method to prevent the corrosion of copper-clad aluminum wire is to apply copper fast drying paint: dry and firm within two minutes, and the color is equivalent to that of copper. This is very convenient for users who use copper clad aluminum wire. Because the user can cut the wiring at any part, the broken end must be exposed to the air. In order to prevent electrochemical corrosion after long-term exposure, the end can be immediately coated with quick drying paint.

3. Copper and aluminum in the section of copper clad aluminum wire are in direct contact. If there is electrolyte on the surface, there will be electrochemical corrosion. If the copper-clad aluminum wire is placed indoors for a long time, the indoor humidity is not large, and the electrochemical corrosion will not occur. If it is exposed outdoors, the corrosion phenomenon will not be too serious due to the corrosion covering its end, but it will produce obvious corrosion phenomenon when there is often water.

advantage:

1. Copper clad aluminum technology is relatively low in price because its material is not pure copper. In weight, because the measurement unit of wires is often meter rather than weight, it saves transportation costs,

2. Due to the "skin effect" of high-frequency signals, copper-clad aluminum wire and copper-clad steel wire have the same conductivity as pure copper wire when transmitting high-frequency signals (greater than 5MHz).

Disadvantages:

1. In terms of electrical performance, because the conductivity of aluminum is worse than that of copper, the DC resistance of copper-clad aluminum conductor is greater than that of pure copper conductor. Whether this has an impact mainly depends on whether the cable will be used for power supply, such as providing power to the amplifier. If it is used for power supply, copper-clad aluminum conductor will cause additional power consumption and voltage reduction.

2. Because aluminum is easy to oxidize, it is not recommended to use copper-clad aluminum wire in places where wires are easy to heat. Copper core cables must be used in places with high temperature resistance and strict requirements as required by civil building design specifications. Therefore, copper clad aluminum is often used to replace aluminum wire in shopping malls, and copper clad aluminum is rarely used to replace copper wire.

There are three ways to distinguish between pure copper and copper-clad aluminum wires

1、 Look at the section. Because it is easy to see if copper clad aluminum is used for thicker wires. Therefore, generally, copper-clad aluminum is a flexible wire, which is composed of many small filaments. But as long as the section is cut, you can identify the material by looking at the whitened (aluminum color).

2： Fire method. Just use a lighter to burn. Look at the burning phenomenon and the results after burning. Copper clad aluminum and copper clad aluminum magnesium wires. When the flame contacts the wire, the conductor will sag in a straight line, which is not easy to burn out. After burning, the conductor color is gray or darker; Because the melting point of aluminum is lower than that of copper.

Difference: the conductor of copper-clad aluminum after burning will break with a twist of your finger, which is relatively brittle and will break into multiple sections. If the oxygen free bare copper wire forms a ball like object after burning, it is the copper wire. The thickness of the copper wire is different, and the result is different after burning. The fine wire melts and the thick wire is the same.

3： Scrape with a tool. The tinned copper wire appears yellow after scraping, which is copper. Oxygen free bare copper wire is still primary color and copper after scraping. While the copper-clad aluminum wire and copper-clad aluminum magnesium aluminum have snowflakes and white spots. Or the same effect can be obtained by placing the wire on the cement ground for friction. Copper clad steel wire can also be identified by this method or by magnet.

Source: Changjiang nonferrous metals network

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