Can copper and aluminum wires be connected together?

Now with people's knowledge of copper, aluminum, two materials, gradually reached a consensus. From the economy, practicality, cost-effective and other perspectives, the open line generally use aluminum wire, dark line are using copper wire. So how should copper and aluminum wires be handled at the joints?

Copper and aluminum wires can not be directly connected together

Between the copper wire and aluminum wire, do a common wire joint, is not allowed. This is because the resistance at the joint is bound to increase, and the higher the resistance, the worse the heat will be. And higher temperatures increase the rate of oxidation of the aluminum. It so happens that the joints of aluminum and air contact area is much larger than the insulating layer wrapped in the place, so, again increased the rate of oxidation of aluminum, aluminum oxidation, will form a layer of oxide film on the surface, affecting the conductivity. Moreover, the higher the current in the circuit, the faster the oxidation of aluminum.

See here may you think, aluminum wire and aluminum wire between the joints, will also occur the above consequences. In fact, it is not, heat is only one of the conditions that accelerate the oxidation of aluminum, if it is only due to heat, it is not enough to affect the wire in the short term. Copper and aluminum wires connected together, the most deadly is "galvanic corrosion".

I do not know whether you remember the primary battery in the primary school reflected - impure metal and electrolyte solution together, the more active metal will lose electron electron and oxidized, thus causing corrosion of the more active metal.

To give an example of the most common electrochemical corrosion, iron rusts - steel is exposed to humid air, and water in the air comes into contact with the steel. At this point, iron, water, and carbon in the steel form a primary cell, and the iron, which is a more active metal, loses electrons and is oxidized, forming iron oxide (rust).

In the above reaction, the active metal iron is the negative pole of the battery, and carbon is the positive pole of the battery. Copper and aluminum is the same reason, the reactivity of aluminum is much higher than copper, so the aluminum as a battery negative pole, quickly oxidized corrosion, and the higher the temperature (the higher the current) oxidation rate faster, the formation of more oxide film, affecting the conductivity of the wire.

How to connect copper and aluminum together

1. Copper and aluminum connector (or copper and aluminum wire clip)

Copper and aluminum connector is a more convenient method. Install a copper-aluminum connector on the aluminum wire, and then connect it directly to the copper wire.

The copper and aluminum connectors are tightly welded together so that there is no gap between the copper and aluminum metal, and there is no contact with the electrolyte, the water in the air. This method completely eliminates galvanic corrosion.

2. Soldering

Lazy to buy copper and aluminum connector, you can follow the practice of copper and aluminum connector, welding. When soldering, make sure that the copper and aluminum are as tightly connected as possible, so that there is no place exposed to the air.

3. Coating tin

Tin can also be applied to the area where copper and aluminum come into contact to eliminate contact between the joints and the air.

Whether it is soldering or tinning, can only try to joints and air contact. However, manual soldering is not as accurate as machine soldering, therefore, if possible, you should use copper and aluminum connectors.