After brazing a workpiece, the oxides generated by heating during the soldering process and the residue remaining with the flux may seriously affect the appearance, service life, and subsequent processing (such as spraying, plating, etc.). Therefore, it must be Weld and affected areas are cleaned.

1. In soldering, the active flux residue containing rosin can be removed by an organic solvent such as isopropyl alcohol, alcohol or trichloroethylene. A flux composed of an organic acid and a salt is generally soluble in water and can be washed with hot water. A solder composed of a mineral acid is dissolved in water and thus can be washed with hot water. A flux containing an alkali metal and an alkaline earth metal chloride such as zinc chloride can be washed with a 2% hydrochloric acid solution.

2. The borax and boric acid flux residues used in brazing are substantially insoluble in water and difficult to remove, and are generally removed by sand blasting or polishing. A better method is to put the brazed workpiece into the water in a hot state to cause the flux residue to burst and remove.

Common brazing cleaning methods:

1,

(1) The residue of the fluorine-containing potassium borate or potassium fluoride hardener (such as qj102) can be boiled or removed in 10% citric acid hot water.

(2) Soak in a 25% hydrochloric acid solution at 60 ~ 70 ° C, stir for 30 ~ 120 seconds, take out cold water rinse.

2. The solder residue for aluminum can be removed with an organic solvent such as methanol.

The aluminum hard residue is highly corrosive to aluminum and must be removed after brazing. The cleaning methods listed below can give better results.

(1) Soak in hot water at 60~80 °C for 10 minutes, carefully clean the residue on the brazing joint with a brush, rinse with cold water, soak in hno3 15% aqueous solution for about 30 minutes, then rinse with cold water.

(2) Rinse the hot water at 60~80 °C for 5-10 minutes, soak it in 65~75°C, cro3 2%, h3ro4 5% aqueous solution for 5 minutes, then rinse with cold water.