How to solder aluminumJune 24, 2013
Masters have no difficulty in brazing copper, brass and steel wires and parts, but if you have to deal with aluminum surfaces, the solder does not even stick to the product, and soldering turns into anguish. Difficulties are caused by the fact that a thin but very strong film of Al2O3 oxide is formed on the surface of this metal. You can mechanically remove this film — for example, to smooth out a product with a needle file, but if water comes into contact with air, the metal will immediately be covered with film again.
Despite the difficulties encountered, it is possible to solder aluminum products. There are several ways to solder aluminum.
Excellent results can be obtained using the following alloys:
- two parts of zinc and eight parts of tin
- one part copper and 99 parts tin
- one part bismuth and 30 parts tin
Before soldering, both the alloy and the part itself must be warmed up well. It should also be remembered that this soldering method should use soldering acid.
Aluminum soldering using special fluxes
Standardly used fluxes do not dissolve the oxide film on the surface of aluminum, therefore it is necessary to use special active fluxes.
Flux for aluminum soldering is used to work with tin-lead solders at a working temperature of 250-360 degrees. Such a flux, both when soldering and when tinning, removes the oxide film well, cleans the surface of the metal and as a result solder spreads better on the surface. All this leads to the creation of a more dense and durable connection of the fused parts. The excess of this flux is easily removed with solvents, alcohol or special liquids.
Also, this flux can be considered universal, since it can also be used to work with nickel, copper, stainless steels, etc.
Other ways to solder aluminum
There are also non-standard ways to solve this problem, for example:
- Place the soldering on the aluminum products carefully cleaned and put a couple of drops of concentrated copper vitriol. A small piece of copper wire is trimmed rolled into a circle with a diameter equal to the soldering point, and the free end of the wire is connected to the "plus" output of a 4.5 volt battery.A piece of wire with a rolled circle is lowered into a small amount of copper sulfate. The minus of the battery must be connected to the part on which some layer of copper will settle after some time. After drying, the necessary parts or wires can be welded to this place in the usual way.
- In this case, an abrasive powder is used, mixed with a small amount of transformer oil to form a liquid paste. This paste is applied to cleaned products for soldering. Further, the soldering iron is well poured and rubbed these places until it is released on the surface of the tin layer. Then the parts are washed and then soldered by the usual method.
- This method will require a transformer. Its minus is connected to the product, and a copper wire of large cross section, consisting of smaller wires, is connected to the plus. If for a short time this wire is connected to the place of the future soldering, a micro-soldering of copper and aluminum will be produced, which will further allow soldering the wires in the usual way. Soldering acid can be used to simplify the process.
Soldering aluminum cookware (without a soldering iron)
Aluminum dishes have a certain demand from housewives,but sometimes it fails, and in order not to buy a new one (which costs a lot), you can repair such products by soldering without a soldering iron. The method below is suitable for sealing small holes (up to 7 mm in diameter).
- It is necessary to clean the place of soldering to metallic luster using emery paper or a file. If the dishes are enamelled, then around the hole to be filled up, the enamel should be removed within a radius of 5 millimeters. To do this, lightly tapping the hammer from the dishes beat off the enamel. Then be sure to clean the metal.
- The place of soldering is smeared with soldering acid or filled with crushed rosin. From the inside, a piece of tin is applied to the hole, and then the container is heated above the stove fire. If the dishes are enamelled, then it is better to heat it above the spirit lamp - this gives a more pointed heat, and therefore the rest of the enamel will not crack due to the high temperature.
- When heated, the tin melts and tightly closes the hole in the pot. In this case, the help of a soldering iron is not needed.