SU802409A1 - Method of dyeing aluminium and its alloy articles - Google Patents

Description

The invention relates to the preparation of painted oxide coatings on articles made of aluminum and its alloys. A known method of anodic anodizing of aluminum products in a solution containing boric acid or ammonium tartrate at a voltage of 45-50 V for 1.5-2.5 min. G. There is a known method of porous anodizing aluminum in a solution containing hexavalent chromium anions, for example chromic acid at 4 ° -43 ° C, voltage 20-25 V for 20-90 min | j2. However, both known methods are intended only for producing electrically insulating oxide films without their subsequent staining. There is a method of coloring products from aluminum and its alloys, excluding porous anodizing, electrochemical painting of an anode film with alternating current in a solution containing nickel at 18–50 ° C, current density O 1 15 A / dm, voltage 5–8 OV for 1 -10 min and subsequent treatment in boiling distilled water with a small addition of nickel acetate. However, in this method, only one-color dark bronze coating is obtained. The closest to the invention is the known method of dyeing products from aluminum and its alloys, including porous anodizing in an acidic solution containing sulfuric acid (with subsequent growth of the oxide film in a solution of phosphoric acid) and electrochemical staining of the anodic film with variable AC in solutions of salts , for example, nickel, cobalt or tin at a voltage of 9-2OV, current density 0.13-O, 3 A / dm for 0, 12–12 min I. In this method films of golden, blue, bronze and black colors are obtained . However, the known method, including double porous anodizing, does not allow to preserve the original brilliance of the treated surface. The purpose of this invention is to expand the color gamut of a colored film while maintaining the gloss of the coating. The goal is achieved by carrying out nonporous anodizing before porous anodizing. At the same time, non-porous anodizing is carried out in a solution containing boric or tartaric or citric acids and / or their salts at 5–45 ° C, and the voltage of ZO-10OV for 1–1 Ohms. Porous anodizing is carried out in a solution containing O-50 ° C, voltage 20-8OV for 20-90 min, and electrochemical staining is carried out in solutions of salts of copper, nickel, cobalt, tin, iron, silver, cadmium, zinc, lead, or gold at 15- "30 C, current density O, 3 1, O, voltage 8-5OV for 1-10 min. The method allows deep and uniform painting of the surfaces of pure aluminum (99.9-99.0%) and some of its alloys, for example, with magnesium (up to 6%) from blue to dark blue without the use of expensive paints, at the same time, the coloring is much more resistant to luminescence. The method expands the range of colors of anodized aluminum dyeing in comparison with the known one, allows to maintain a good gloss and improves the uniformity of the dyeing. When finishing polished products, up to 60% of the gloss from the initial surface gloss is retained, whereas when finished without barrier anodization, the gloss of the coatings is only a few percent of the initial one. The color of the oxide coatings depends little on the composition of the solution of coloring, which is convenient and makes it possible to easily control the intensity of the color. Before anodizing, the surface of products made of aluminum or its alloys is degreased in acetone, alkaline etching is carried out in a 5% solution of sodium hydroxide at 5 ° -6 ° C for 1 min and decapitated in a 10% solution of nitric acid at room temperature for 5 min, then electrolytic polishing is carried out in an ethanol solution containing 1.5 M perchloric acid (57.8%) at room temperature and a current density of 20 A / am for 3 minutes. Cathode stainless steel. The product is washed between the non-porous and porous anodizing. Cathodes in anodizing baths use graphite. Auxiliary electrodes in the dyeing bath are graphite, stainless steel, or other metals that are insoluble in the dyeing solution. Staining is carried out with stirring of the solution (air or mechanical). All solutions used are prepared in distilled water. Electrostatic staining is recommended to be conducted with alternating current of industrial frequency or pulsed (pulsed) current. The invention can be illustrated by several examples presented in the table (p. 6-8).

non-porous anodirova

3% ammonium tartaric,

3% ammonium citrate

1% ammonium citrate.

1% boric acid, 3% boric acid,

0.5% sodium tetraborate. 20% aqueous ammonia solution (20 ml / l). 20% aqueous pRCTBOp of ammonia (5 ml / l) 1% - citric acid temperature, C (T) 20 5 20 post voltage. B (U) 7O 307 Duration, min (1) 515 5.5 7.0 5.5 reflectivity,% before anodization, 82 79 80 77 after bespore. porous anodizing: 5% chromic anhydride + 7% chromic anhydride 8% potassium dichromate.

0.35% sulfuric acid

pH

reflectivity after porous anodizing,%

Staining in a solution containing (g / l):

Ni5047H20-15, H, jBO - 15-ipH 4, 65 5p50d-20,

pH 1.5-3Ct 5048Hj, 0-20,

Table continuation

31

37

42 35 25 18 34 27 45 20 20 4530 10 00 7О 70 1ОО7О 1ОО 7О551О15, 5 5.5 4.2 5.54.0 4.7 9 75 80 7677 81 9 76 80 7576 80 pH. Si5Od5N O-15, Nd504-15 pH K S0 7HgO-150, H, pH 4.2 2 O 20 15 2 O 29 29 - 2 Iper. g Oper, A / dm - - 1,0 impulse current, sun, pulse. ) the frequency of them. in minutes promparability seconds

Claims (4)

reflectivity,% As SPECIFICALLY from the table, only using a combination of two processes (non-porous and porous) anodizing before upvc folic coloration makes it possible to obtain a positive effect (2-3 times better gloss is maintained according to B xBOCTBt get more different color tones of color). Claims 1. A method of painting products from aluminum and its alloys, including porous anodizing in an acidic solution and electrochemical painting of an anode film with an alternating current in solutions with 32 33 23 27 0 2O 20 15 2O 2O 0 - - - - 48 - 0.3 - 0.5 0.5 lei of metals, characterized in that, in order to expand the color gamut of the painted film while maintaining the gloss of the coating, before porous anodizing lead nonporous anodizing . 2. The method according to claim 1, wherein the non-porous anodizing is carried out in a solution containing boric or tartaric acid and / or their copolymer at a voltage of 30-1.5 for 1-10 min 3. The method according to claim 1, which is also distinguished by the fact that porous anodizing is carried out in a solution containing hexavalent chromium anions at 40-50 ° C, applying 2O-HOB voltage for 2O-9Omin. 9 R024O 4. The method according to claim 1, about a hl of h iu iu, and with the fact that electrochemical staining is carried out in solutions of salts of di, nickel, cobalt, tin, iron, silver, cadmium, zinc, lead, or gold at 15–3 ° C, current density 0.3–1.0 A / dm, voltage 8-SOB for 1–1O min. 5. The method according to W1. 1 and 2, that is, with the fact that non-porous talent is carried out in a solution of citric acid and / or its salt. 910 Priority in paragraphs 21.O8.79 of clause 5. Sources of information taken into account in the examination 1. US Patent No. 3734837, for l. 2O4-36, pub. 1973. 2. Australian Patent Nfe 415279, cl. 07.6, publ. 1971. 3. Patent of France J9 2052132, cl. From 23 b 9/00, published 1971. 4. US patent number 4O22671,) class. 204-42. publish 1977.