DE1064316B - Process for the production of phosphate coatings on wires and tapes - Google Patents

Description

Process for the production of phosphate coatings on wires and tapes Phosphate coatings are usually placed on wires, especially around the following To facilitate cold drawing, by dipping the wire coils in a hot bath Phosphating solution. Approximately 10 minutes are required to apply a coating, which facilitates the subsequent pulling of the wire in a satisfactory manner. the However, coatings are not uniform because bare spots are created on the wire ring can by touching the individual wire windings and covering them, especially in the middle of the wire bundle. The penetration of the solution inside of the wire bundle is often insufficient, so that the solution inside the wire bundle being overused.

It is known that phosphate coatings formed by spraying the phosphate solution be formed on a metal surface, for example on body panels, in be trained in a much shorter time, d. H. in about 1 minute.

It has now surprisingly been found that phosphate coatings on moved wire or metal band by very brief immersion can if the wire or tape is continuous in the axial direction through a Phosphating solution is passed through which contains a small amount of accelerator and has a score greater than 30. The score corresponds to the solution the number of cm3 11/1 sodium hydroxide solution that is required to add 1.0 cm3 of the coating solution neutralize with phenolphthalein as an indicator. It's surprising. that on In this way, the coating can be formed in an even shorter time than in the spraying process.

If the solution is accelerated too much, i. b. if too much accelerator is present in the solution, then too much of the degradation product of the accelerator remains in or on the coating and there is insufficient phosphate from the Solution taken out to obtain a coating of the required thickness. Coatings, applied from such solutions close a white, granular sludge or dust or are covered with it. If on the other hand the concentration If the accelerator is too low, the wire can be amorphous, often bluish in color Have coating in place of the desired crystalline coating.

The solutions preferably contain chlorate as an accelerator. The required acceleration is preferably obtained when using solutions according to patent 856 544. These solutions are monophosphate solutions that contain chlorate or a mixture of a chlorate and a nitrate as an accelerator and in which the phosphate content, calculated as P.05, is Chlorate, calculated as Cl 03, and nitrate. calculated as N 03, are chosen so that the ratio is between 0.1 and 0.6.

The preferred metal in the phosphate solution is zinc and lasts the solution at or near its equilibrium temperature. Preferably chooses one solutions that are in equilibrium at a temperature between 77 and 82 ° C are located. In the case of the preferred solutions, temperatures of about 77 ° C. come into consideration.

When the coating is formed on the wire in less than 15 seconds should be because it moves at greater speed or because it moves faster is needed or because there are difficulties, a satisfactory coating a special steel, then you can heat the wire when it comes out the phosphating solution comes and carries a film of this solution with it. It is necessary, that the solution film carried along by the wire from the solution is uniform, for example with the help of stripping devices. This prevents the formation of a coating that occurs during has started to pass through the solution. The heating one applied film of a phosphoric acid solution to form a phosphate coating is known.

The heating can be, for example, by gas flames or high frequency induction heating be effected. However, it is desirable to be highly oxidizing during heating or avoid strongly reducing conditions. When the wire is heated then you should preferably choose the number of points between 50 and 70.

With wire drawing, the required layer weight depends on the material of the wire and the drawing conditions. In general, layers with a Layer weight of about 65 mg / dm2, although layer weights of only 23 nig / dmz or 95 mg / dmz can also be usefully applied. The layer weight can be increased are by adding 0.1 to 0.2% of an aminopolycarboxylic acid or from 0.02 to 0.08% of a soluble copper salt for the phosphating solution. More options to influence the layer weight, select the throughput speed the bath, varying the number of points of the solution, heating the discharged solution film.

A satisfactory phosphate coating can be done on wire in 15 seconds or less Can be applied even shorter if the wire is continuously treated with a pickling solution runs before it is passed through the phosphating solution. When you wire up Covering this way, one preferably chooses a score of the solution between 60 and 80.

The phosphated wire can be made of a coating in a known manner Get lime or borax.

When the wire is to be stored for some time before cold processing or any other treatment, then it is recommended to use the wire rinse in cold water immediately after applying the phosphate coating, because a wire that has not been rinsed tends to rust.

When carrying out the process according to the invention, one can use the Wire in several strands continuously at a speed of about 18 m / 1 @ Iiriute through a tempering furnace and through a short container of water Pass the cooling of the wire through into the pickling tank. The pickling solution can, for example be a cold 10% hydrochloric acid solution. Guide rollers around which the wire runs, are arranged so that the wire is immersed in the pickling solution for about 1 second. Then the wire can run through a scraper, preferably over water flows away to remove carbonaceous contaminants, and then through another container that holds water for washing the wire. Then only step the wire into the phosphate solution, which is arranged so that the wire is in it Immersed for 7 seconds. The container can be elongated, flat and flat. The wire should then be passed through cold water again for the purpose of rinsing "-earth. Zero becomes a coating of lime or borax on the moving Wire applied by running it through a suitable bath for about 1 second. The wire can then be dried by passing it through a drying oven will. The wire is now ready for cold drawing and can be used directly can be inserted into the nozzle or initially wound up until it can be pulled target.

The advantages of the method according to the invention are extraordinary short treatment time and low consumption of chemicals. Another advantage consists in that, besides the sludge, caused by ordinary thermal dissociation as is common to all phosphating processes, no sludge is formed will. The only sludge formation that occurs is during the short one Time of treating the wire in the solution. The efficiency of the procedure is therefore greater than with known methods.

The discharge is limited to the film of solution that is formed by the wire during Stepping out of the solution is led out evenly. This is less than the large amounts of solution produced when a wire bundle is removed from the solution can be removed. The consumption of chemicals can be further reduced by that the even film that is taken out on the wire to complete the formation of the coating is used.

The process is explained using a few examples.

Example 1 The phosphating solution had the following composition: 48.4 g / 1 P 041 11.4 g / 1 C103, 2.0 g / 1 N 03, 3.2 g / 1 Na, 13.6 g / 1 Zn.

The score of the solution was 80, and the solution was between Held at 82 and 88 ° C. Two sets of steel wire of 1 mm 0 and a carbon content of about 0.65% C were passed through the Tempering furnace, the pickling solution and the other process steps described above passed through. The wire is immersed in the phosphating bath for 13 seconds. Two Wire sets treated in this way were running at a terminal speed from 600 to 825 m / minute wet drawn, with it in ten puffs to a final diameter deformed by 0.42 mm.

Two more sets of wire that weren't pickled were also through the phosphating solution is sent at a rate that requires an immersion time of 13 seconds. After leaving the solution, the wire was through the flame of the Bunsen burner to complete the coating formation and dry the wire. The wire was immediately sent through a solution that contained about 511 / o borax, and dried by passing it over a steam coil. Two sets of wire treated in this way were wet drawn with one Top speed of 600 or 815 m per minute and resulted in one in ten moves Final diameter of 0.42 mm. The results in both cases were so satisfactory that as if the wire was dipped in a bath for 5 to 10 minutes would have been provided with the coating.

Example 2 In this experiment the phosphate solution was the same as in example 1. A wire with 0.5% carbon content was normalized, in cold Hydrochloric acid pickled and used to remove carbonaceous material by a Run the scraper over which water was allowed to flow. It then became rinsed in water and through a Phosphate solution at one rate of 0.30 m / second passed so that he was immersed in the bath for 11 seconds. Of the Wire was then allowed to air dry for 6 seconds, rinsed with water, and passed through a boiling borax solution. It was dried in an oven and wound up. Two sets of the wire, which was 0.9 mm in diameter, were then wet pulled in ten pulls at a speed of 825 m / minute, in one case up to a final diameter of 0.31 mm, otherwise 0.23 mm.

Example 3 A phosphate solution was prepared by adding 120 g zinc oxide, 375 g phosphoric acid to 1000 g water. 70 g of this stock solution were diluted in 1 liter and 0.5 g of sodium nitrophenolsulfonate was added. The solution had 40 points. Steel wire was treated therein for 10 seconds and then as in the example 1 described, dried. A very finely crystalline, usable coating resulted.

Example 4 A phosphate solution was prepared from 725 g of zinc oxide, 730 g of nitric acid with a specific gravity of 42 ° Be, 2400 g of 75% phosphoric acid, made up with water to a total weight of 5400 g. 70 g of this stock solution were diluted to 1 liter and 1.5 g of sodium nitrite were added. The answer was 40 points. Steel wire was treated in this solution at 70 ° C. for 10 seconds and then dried. The wire had a very thin, crystalline coating that made it easier to cold-draw the wire.

Example 5 A coating solution was prepared by adding 40 g primary zinc phosphate and 5 g nitroguanidine to 10 g water. Had the solution a score of 40. Steel wire was soaked in the solution in the cold for 15 seconds and then, as described in Example 1, heated. Coatings were obtained that were used to facilitate cold drawing of the wire.

Claims (6)

PATENT CLAIMS: 1. Process for the production of a phosphate coating on wire or tape, characterized in that the wire or tape is continuous in the axial direction by a phosphating solution, preferably zinc phosphate solution, which contains a small amount of accelerator and a score of more than 30, preferably 50 to 80, short time, preferably not longer than 15 seconds, is passed through. 2. The method according to claim 1, characterized in that the wire or strip is moved continuously in the axial direction through a known monophosphate solution which contains a chlorate or a mixture of a chlorate and a nitrate as an accelerator, the phosphate content being calculated as PO, chlorate, expressed as C103, and nitrate, calculated as N O31 chosen so that the ratio is between 0.1 and 0.6 and the solution has a score greater than 30, preferably 50 to 70 points. 3. The method according to claim 1 and 2, characterized in that that the wire or strip is continuously passed through a pickling solution before phosphating is passed through. 4. The method according to claim 1 to 3, characterized in that that the wire or tape after exchanging from the phosphate solution with the removed solution film is heated. 5. The method according to claim 1 to 4, characterized characterized in that the phosphate solution is applied at 77 to 82 ° C. 6. Application of the method according to claims 1 to 5 for facilitating the cold drawing of wires. Documents considered: German Patent No. 856 544; W. Machu, "Non-metallic inorganic coatings", 1952, p.246.