In the manufacture of household appliances, aluminum and its alloys: silumin, duralumin - are used very widely. Of these materials, both product bodies and wires for various devices are made.
What to do if it becomes necessary to solder an aluminum part or solder a loose wire from this lightweight material? Soldering metals in general, and aluminum in particular, is, as a rule, a non-trivial task that requires knowledge and experience. Both aluminum itself and alloys with its participation have an unpleasant property. Under the influence of air oxygen, parts of this metal are coated with a strong oxide film, which makes brazing aluminum a difficult task. After all, oxide prevents the reliable connection of soldered parts. In this material you can read about how to correctly braze aluminum at home using solders that include lead: POS-50, POS-61 and POS-90.
The first way. If you need to solder a pair of wires consisting of aluminum to each other, you should tin them well first. A rosin is applied to the ends of the soldered wires, the sandpaper of the middle numbers is placed underneath, and with a hot soldering iron (which also needs to be tinned beforehand), the wire is pressed to this skin. In the process, you need to constantly add rosin, and in no case should you remove the soldering iron from the metal. This operation is repeated many times until the wires can be tinned properly. Then you can start the soldering. If, instead of rosin, alkaline oil is used to clean weapons or mineral oil used to lubricate sewing machines, then preparing for the process and soldering aluminum itself will not cause difficulties. Unless, of course, you have at least a little experience in these matters.
The second way. It turns out well to solder aluminum in sheets. A rosin is applied in place of the seam, into which small metal filings are crumbled, then you need to go through the seam several times with a tinned hot soldering iron, constantly adding solder. The meaning of this method is that the sawdust with sharp angles will begin to scratch and peel off the oxide film, and when it does not interfere, the tin from the solder is well connected to the base, and brazing aluminum becomes an easy task.
The main thing is to remember the rule: the thicker the sheet of aluminum, the more powerful the soldering iron should be. If you are faced with the task of soldering thin sheets, a 50 W soldering iron will do just fine. In the case when the sheet thickness is a millimeter or a little more, you need a 90 W soldering iron. And if you need to braze aluminum in sheets that consist of plates of two millimeter thickness, then before brazing, you will have to preheat the metal, then apply flux and then begin the soldering process. In the second method, as in the first, mineral oil can be used instead of flux.
The third option. Before proceeding directly to soldering, you should perform the “copper-plating” procedure on the element that you have taken to work. For these purposes, a galvanizing installation is suitable, but if it is not at hand, you can do without it. Begin by applying concentrated copper sulfate to the soldered area. Then connect the negative terminal of the battery or battery to this part. Lead positive contact to the copper wire fixed on the fluffy part of the toothbrush so that it does not touch the aluminum surface due to the protruding bristles. After a certain time, at that point of the part that you were about to solder, a thin layer of copper will deposit. It must be washed with water, dried, and then tin in a standard way (using a soldering iron).