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Why Can't Copper Wire And Aluminum Wire Be Directly Connected?

Update:04-08-2019
Summary:

1. For copper wire and aluminum wire, the potential is […]

1. For copper wire and aluminum wire, the potential is actually different. When we use copper wire and aluminum wire to connect, the place where copper and aluminum are connected will accelerate the oxidation of aluminum wire due to the voltage reaction. In this case, it takes a long time. When there is a contact between the copper wire and the aluminum wire, the contact is not true.

2. In fact, for this problem, we also introduce a chemical problem. For the metal from the chemical point of view, there will be lively and inactive points. For example, our common gold will not rust any time. The situation, this also shows that gold is not lively, but after the iron meets the water, it will not be long before the rust will prove that the nature of iron is lively, if we connect the wires of two different materials when wiring If you are together, it will speed up the oxidation of the live line. If the copper wire is compared with the aluminum wire, the aluminum wire will be more active. If it is directly connected, it will accelerate the oxidation of the aluminum wire, and various problems will affect our normal. use. 

3. When we connect the copper wire and the aluminum wire directly, the wire contact surfaces of the two materials will easily generate electrolyte under the action of moisture in the air, carbon dioxide and other substances, so that aluminum wire is formed. The galvanic cell in which the negative electrode and the copper wire are positive electrodes causes galvanic corrosion of the aluminum wire, and eventually the contact resistance of the copper wire and the aluminum wire is increased. 

4. For the comparison between the copper wire and the aluminum wire, since the difference in thermal expansion coefficient is relatively large, after a plurality of hot and cold cycles in the normal use operation, a large gap is formed between the contact points of the copper wire and the aluminum wire. Therefore, the contact of the line is affected, and the contact resistance is increased. If the resistance value becomes large, the line temperature is increased during operation, and if the line temperature is increased, the corrosion of the line is increased, thereby generating a vicious circle. If the situation is serious, it will also lead to smoke and fire on the line, which is prone to danger.

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