SU836213A1 - Aqueus solution for pickling aluminium and its alloys - Google Patents

Description

one

The invention relates to the chemical treatment of the surface of metals, namely, to the etching of the surface, aluminum and its alloys in acid solutions before electroplating.

Solutions for etching the surface of aluminum and its alloys before electroplating, containing nitric acid and hydrofluoric acid, are widely known 1

However, these solutions are not universal for all aluminum alloys. The use of these solutions is limited to one or two types of alloys. For acid etching, each alloy of a certain grade must use a new, specially designed solution. Otherwise, there will be a decrease or lack of adhesion of galvanic deposition to the substrate.

The closest in technical essence to the invented aqueous solution is a solution for etching aluminum and its alloys, containing nitric acid, hydrofluoric acid and ammonium hydroxide 21.

This solution is used to treat aluminum alloys containing silicon, copper and some other alloying materials in certain quantities. However, for alloys containing a greater amount of alloying additives: (, AL23, etc.) and for alloys containing manganese (AMgb, etc.), this solution does not give satisfactory results.

The aim of the invention is to create a universal solution for acid etching, to improve the quality of the surface and the adhesion of the halo vanical coating with the base for alloys containing a large number of alloying additives.

The goal is achieved by the fact that the solution contains as sources of ammonium ions and fluorine ions, respectively, 1mmonium nitric acid and hydrofluoric acid in the following ratio of components, (Betf.%) Sulfuric acid 10-30

Hydrofluoric acid4-15

Ammonium nitrate; Shy 0.01-7 Water-Salting Operating mode: solution temperature 55-6C, sample processing time 1 min. All the reagents used for the preparation of acid etching solutions are used in H mark and are made in the Soviet. The proposed solution is used in the following scheme for the preparation of the surface of aluminum (ADOM) and its alloys D16, AMts, AMgb, B95 and AL23: degreasing in A-72 gasoline; drying; Etching in a 5% solution of NaOH for 2 minutes at a temperature of water; etching in an acid solution according to the proposed invention at a solution temperature of 5070 0 for 1 minute. After this acid treatment, the surface is smooth, light sulfur, pure aluminum color. When viewing the surface of the samples through the microscope of ishamam, no dopants are observed. The entire surface is well moistened with water. Then immersion coating is applied in a fluoroborate immersion solution of the following composition (g / l): Zinc fluoroborate 40 Fluoroborate nickel Fluoroboron, t ammonium -, The immersion time of the samples in this solution is 30 sec, followed by a cathode current pulse of 1 K 1 A / dm for 30 seconds Samples of aluminum and aluminum alloys in an immersion solution: are processed at a temperature of 20 s and a pH of 4-4.2. After watering, the copper plating is carried out in a pyrophosphate electrolyte of the following composition (g / l): Potassium pyrophosphate. 360 Copper Pyrophosphate 25 Ammonium Oxapate 18 Sodium Carbonate Samples in the above solution are processed at a temperature of 40 ° C and 1.5 A / dm, and a pH of 8.5-9.0. Then the samples are washed with water and nickel is precipitated from the sulfamine bath of the following compound (g / l): 312-320 Nickel sulfamate Crystalline nickel chloride Boric acid Nickel plating is carried out at a solution temperature of 40 s, pH 3.5-4.2 and current density ± 5 A / dm After drying with water and drying, the adhesion of the galvanic sediment to the base is measured by a semi-quantitative method using a Kovostav tensile testing machine. Electroplating was buried interlocking with the base, blistering, and also withstood the adhesion of GOST 16875-71. Below are the compositions of the proposed aqueous solution (wt.%): Composition 1g. Nitric acid (concentrated) 19.5 Hydrofluoric acid (d :: l, 24) Ammonium nitrate2, 7 acidic Water The rest is up to 100%. Operating mode: temperature, m processing of samples in solution in. The surface after processing is considered even, light sulfur. In the case of electroplating copper and copper, the results of the measurements of the strength of the coupling for the alyumkni and its melting were as follows (kg / mm): Aluminum (ADOM) 5 AMc3.3 AMGB1.0 AL231.0 B95. 0.35 Composition 2 Nitrogen acid (concentrated) 30 Fluoroforodoforodny acid (, 24) 15 Ammonium nitrate 7 Water The rest is up to 100% Rehgim work: the above mentioned. Ultaty measurements of the strength of galvanic circuits with the basis of the floor are the same as in the composition 1. Composition 3 Nitric acid 10 (concentrated) Hydrofluoric acid (, 24) 4 Lmmonium nitrate 0.01 Water The rest is up to 1100% Mode of operation - higher nytyiti. The results of measurements of the bonding strength of the co-alloying substrate with the base during the pickling for etching the specified solution were as follows (kg / mm): Alkvlinium ADOM5 AMts2.0 AMgb0.4 AL2.15.15 V95 None As can be seen from the data, the strength of the pickle when applying the above-mentioned acid etching etch

It only decreases and is absent for alloy B95.

Data on the effect of the composition of the solution for acid etching of aluminum alloys on the adhesion strength between galvanic deposition and the substrate are given in the table. .

As can be seen from the table, it is possible to obtain strongly adherent galvano-impregnated aluminum from ADOM using both the proposed and known solutions, while on the AMgb, B95 and AL23 alloys (GOST 4784-65) it is possible to obtain sufficient adhesion strength of galvanic depositions and bases. baty samples only proposed solution

An aqueous solution for etching is much more widely applicable for etching aluminum alloys before applying G-coatings than a known acid pickling solution.

The versatility of the created solution makes it possible to etch different aluminum alloys in one bath. This allows you to reduce / sew the production area, the number of service personnel, simplify the technological scheme and improve sanitary conditions by reducing the number of acid baths. As can be seen from the examples, using the created solution of acid etching, it is possible to increase the adhesion of galvanic precipitates to the substrate, and for the B95 and AL23 alloys, which include copper, manganese, zinc, chromium, iron, and silicon, respectively. antimony and magnesium, manganese, titanium, beryllium, iron, antimony, the adhesion between the galvanic oxide and the substrate is reached only after treatment in the proposed acid persecution solution.

Claims (1)

The claims to The versatility of the created solution makes it possible to etch different aluminum alloys in one bath. This allows to reduce production areas, the number of staff, to simplify the technological scheme and improve sanitary conditions by reducing the number of acid baths. ^As seen from the examples, applying created by acid etching solution, it is possible to increase galvanoosadkov adhesion to the substrate, adlya alloys V95 and AL23 whose composition respectively comprises copper, manganese, zinc, chrome, iron, silicon, _f antimony, magnesium, manganese, titanium, beryllium, but: lezo, antimony, the adhesion between the galvanic precipitate and the base is achieved only after treatment in the proposed solution of acid etching 10-30 Aqueous solution for etching alu. jq minium and its alloys, mainly during preparation before plating, containing nitric acid, ammonium ions and fluorions, characterized in that, in order to increase the adhesion of the plating to the base, it is c. as sources of ammonium ions, th fluorine ions respectively contains ammonium nitrate and hydrofluoric acid in the following ratio of components, wt.% Hydrofluoric Acid Ammonium nitrate Water 4-15 0.01-7 Else