DE2302875C2 - Low-smoke flux solutions for hot-dip galvanizing of iron objects - Google Patents

Description

1 to 5 percent by weight. The HCl content can generally be lower, the higher the content of the above-mentioned solutions in the solutions Is metal chlorides

Of course, the solutions can also contain wetting agents known per se.

The new fluxes combine the advantages of a very good oxide-dissolving effect of the aqueous solutions with the formation of an oxidation-inhibiting surface film when standing or standing. Drying the items to be galvanized.

The fluxes according to the invention already develop their cleaning effect when the iron objects are wetted or when they are subsequently dried, so that when they are immersed in the zinc bath or in the molten salt located on it, the surface cleaning has already been practically completed

example 1

A continuously moving iron belt is degreased as usual and treated with acids.

After the intermediate rinse with water, it is drawn through a flux solution, which is made up of

60 kg zinc chloride,

8 kg of sodium chloride, 11 kg of potassium chloride,

8 kg hydrochloric acid 23 percent and 951 H ₂ O

consists.

The tape is dried in a drying oven,

90

30th the outlet temperature of the same 100 to It is 170 ° C. The galvanizing takes place in a 450 ° C zinc bath.

A perfect galvanizing of the surface is achieved. A smoke development is practical not detectable.

Example 2 With a flux made from

45 kg zinc chloride,

6 kg sodium chloride,

8 kg potassium chloride, 11 kg hydrochloric acid 23 percent and 901 H ₂ O

existed, as in the example! 1 procedure.

The galvanizing of the surface was perfect; the exhaust emissions are very successful.

Example 3 With a flux consisting of

75 kg zinc chloride,

10 kg hydrochloric acid 23 percent and 901 water

was composed, the procedure was as in Example 1.

If the surface was well galvanized, only a small amount of smoke was observed

Claims (3)

1 2 concentrated solutions are used, the claims: contain mainly ZnCl2 and NH4Q, and that any too early HCl elimination leads to an even lower 1. Smokers, containing zinc chloride, have an aqueous cleaning effect on the river rige flux solutions for hot-dip galvanizing 5 From this it can be seen that free KCl only when iron objects after the dry process, dipping the object to be galvanized into the characterized in that it should occur in addition to zinc bath. This is also confirmed by Zinc chloride contain hydrogen chloride, the statements in the journal »Archiv für das the zinc chloride and hydrogen chloride content of the iron and steel industry «, volume 25.1954, issue 1 and 2, Solution 25 to 60 percent by weight is 10 p. 23, last paragraph, left column, after which the chemical 2. Aqueous flux mixtures containing zinc chloride, essentially pickling in dry galvanizing Solutions according to claim!, characterized by the decomposition of the zinc ammonium net, that they also instructed sodium and / or potassium chloride formed hydrogen chloride lium chloride in amounts up to 60 per weight cent, based on the zinc chloride content, is 15 Finally in the British patent keep. 615110 containing hydrochloric acid and zinc chloride 3. Zinc chloride-containing aqueous flux flux has become known, which, however, for the solutions according to claims 1 and 2, characterized by the treatment of copper-plated iron objects that the solutions a chlorine is used, which are then tinned,
Hydrogen content of 1 to 10 percent by weight, ao. Fluxes are also known (patent preferably from 1 to 5 percent by weight, inscription 76 863 of the Office for Invention and Patent Drawing on Zinc, Sodium and / or Potassium in East Germany Berlin), which consist of a mixture of chloride content. Sodium chloride and zinc chloride exist and the practically no smoking, but these river »5 medium has only a very low effectiveness, so that they have not yet been used for galvanizing have been. According to its own, not the state of the art In the hot-dip galvanizing of iron counter-nik belonging proposal contain flux for It is necessary to hot-dip the surface of the same 30 hot-dip galvanizing in addition to sodium and potassium To undergo pretreatment. This is done in the "and / or zinc chloride aluminum chloride as well as substantial by degreasing, treating with acids, if necessary up to 4% ammonium chloride. This such as hydrochloric acid or sulfuric acid, as well as subsequent fluxes practically do not smoke and are on the ßend by treating with flux (yearbook comparable to the other side in terms of their activity Oberfiächentechnik, 1957, 13th edition, pp. 332 to 35 with the most active flux known today, the 360). but consistently a very high ammonium chloride Nowadays systems are used as fluxes and consequently also smoke heavily, sets which, in addition to zinc chloride, are in varying amounts in French patent 504 228 Contain ammonium chloride. Usually described as a flux for the lead, which is carried out by hold these fluxes between 7 and 55 weight- 40 dissolving an ammonium salt and zinc in percent ammonium chloride. It is also possible to produce hydrochloric acid. According to one anticipated, Embodiments which are additionally given to these fluxes contain alkali halides or aluminum chloride (British patent also has a high proportion of ammonium salts, 830 258). Although these fluxes are of the order of magnitude of the zinc chloride content from the point of view of galvanizing, so that this flux is also strong are peaceful, they have the disadvantage that they smoke one. strong smoke development, which is based on the It has now been found that zinc chloride contains associated air pollution is disadvantageous. tend aqueous flux solutions are low in smoke The removal of the smoke components is, however, and at the same time have a high activity when technically very complex. 50 they contain hydrogen chloride in addition to zinc chloride, In the handbook by Heinz Bablik, the zinc chloride and hydrogen chloride content being hot-dip galvanizing, Vienna, 1941, p. 90, it is stated that one of the solutions is 25 to 60 percent by weight.
Explanation of the flux effect are not yet very preferred concentrations of the solutions It has come a long way: It is assumed in part, at 40 to 55 percent by weight zinc chloride and that dry hydrogen chloride gas is a very special hydrogen chloride. This is an effective flux, while other particularly favorable fluxes are those that On the other hand, the opinion is expressed that the removal of metal oxides in addition to the two above-mentioned components without the involvement of chlorides also takes place in addition to sodium and / or potassium hydrogen. In any case, however, metal oxides will have to be removed from the chloride in amounts of up to 60 percent by weight, in the rarest cases, so the zinc chloride content of the solutions is much more likely to be iron salts or simple solid ones. Such fluxes have - after evaporation substances such as the acid-insoluble co-substances fung of the water - a particularly low steel (C, SiO ₂ , etc.), which is known by melting point and a low viscosity. You wer-HCl will not be attacked. in the same concentrations as the alkaline In the manual for hot-dip galvanizing from the 65 chloride-free flux used!
VEB Deutscher Verlag für Grundstoffindindustrie is in the The content of hydrogen chloride can be mentioned from 1 to paragraph 2 of chapter 3.3.6.5.3 on p. 101, 10 percent by weight, based on the sodium, that as a flux for dry galvanizing, potassium and star / or zinc chloride content, preferably