[China Aluminum Network] Copper clad aluminum wire is an aluminum core wire as the main body, outside the plating of a certain share of the copper wire. Because the main function of this type of wire is to transmit signals, the current flowing through it is very small. However, because the electrical conductivity of aluminum is as low as 2/3 of that of copper, national standards require that any wire and cable used for power transmission must be coated with annealed copper wire that is not plated with metal or metal, and aluminum wires (including copper packets) must not be used. Aluminum wire) as a conductor.
Copper clad aluminum wire
Copper-clad aluminum wire copper and aluminum are two kinds of metal electrode potential is not the same, in its end face of copper and aluminum exposed in the atmosphere, if the humidity in the atmosphere is larger, the end face of adsorption of small molecules of water and accumulate into small droplets . Because of the presence of coal incineration products or exhaust from many motor vehicles, SO2 is abundant during the period. SO2 is oxidized into SO3 in the air, dissolved in water droplets to form H2SO4 in the acid solution that erodes the battery, becomes an electrolyte solution, and corrodes the battery. In this etched battery, aluminum is corroded because of its low electrode potential. Even if a piece of metal is not touched with other metals and placed in the electrolyte solution, a corrosive battery similar to the above may also occur. For example, copper is often rich in a few impurities, and the potential of the impurities is usually higher than that of copper. When there is an acidic droplet of copper on the outside, the battery is formed and the copper is subject to corrosion.
In order to avoid electrochemical corrosion at the end of the copper clad aluminum wire, the best way is to block the end of the wire from the atmosphere and avoid corrosion of the copper clad aluminum wire. Currently, two methods are available:
1. Electroplating method to avoid corrosion of copper clad aluminum wire: A layer of copper is plated on the butt joint of copper clad aluminum wire, but it takes too much time (40 minutes). However, it is not a big problem for companies that produce copper-clad aluminum wires because many joints can be electroplated together. It is difficult to coat copper with aluminum.
2. Copper-coated quick-drying paint that avoids the corrosion of copper-clad aluminum wire: Dry and solid within two minutes, with proper color and copper. This is very convenient for users who use copper clad aluminum wire. Because the user can cut the wiring in any part, this broken end must be exposed in the air, in order to avoid the galvanic corrosion after prolonged exposure, you can immediately apply a quick-drying paint on the end. The copper and aluminum sections of the copper clad aluminum wire are directly touched and touched together. If there is an electrolyte on the outside, electrochemical corrosion occurs. If the copper clad aluminum wire is placed indoors for a long time, the humidity in the room is not high and electrochemical corrosion does not occur. If it is exposed outdoors, it will not be too harsh because the corrosion material will cover the corrosion of the end, but there is often water. In cases where significant corrosion will occur.
When the copper clad aluminum wire is connected, the touch resistance decreases as the touch load increases, and tends to remain unchanged later. Because the appearance of aluminum is easy to oxidize, when the load is reduced, the aluminum/aluminum and aluminum/copper have larger touch resistance. As the load increases, the touch resistance decreases. When the copper/copper is connected to the copper clad aluminum/copper clad aluminum, the touch resistance is small even when the load is small, and the two are extremely close to each other. This is also an important reason why copper clad aluminum replaces aluminum.
Cobalt metal is mainly used for making alloy. Cobalt-based alloy is cobalt and chromium, tungsten, iron, nickel group made of one or more of the general term. Tool steel containing a certain amount of cobalt can significantly improve the wear resistance and cutting performance of steel. Stellite hardeners containing more than 50% cobalt do not lose their original hardness even when heated to 1000 ° C. Nowadays, these cemented carbides have become the most important material for use between gold cutting tools and aluminum. In this material, cobalt alloyed with other metal carbide grains together to make the alloy with higher toughness and reduce the sensitivity to impact, the alloy welding on the surface of the parts, the parts can make Life expectancy increased by 3-7 times.
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