SU933826A1 - Method of etching workpieces made of copper-containing alloys - Google Patents

Description

The invention relates to the electrical processing of metals (ECM), in particular to the preliminary preparation of the surface of parts made of manganese-copper splices (75% manganese) before applying electroplating of alkaline electrolytes that do not contain halide ions, such as zinc, cadmium, copper, etc. .

At present, new forms of memory materials for the manufacture of elements of electrical circuit protection devices are starting to be found in electrical engineering. Thus, in the manufacture of circuit breaker releases, instead of a bimetal, the material of a reversible mechanical shape memory based on a manganese-copper alloy (75% Mn, 25% Cu) can be used. In order to obtain reliable electrical contact, as well as for corrosion protection, parts made of a manganese-copper alloy should be coated with an appropriate material. The difficulty of coating this alloy is that the ingredients (Mn and Cu) are very different in the magnitude of the normal elactrode potential: for manganese "fo -1.18 V, for copper fo + 0.345 V ) An additional difficulty is that manganese has a variable valence, and tetravalent manganese compounds are amphoteric. Therefore, the behavior of an alloy coated with a layer of oxides in a solution is determined by the oxidation-reducing properties of the solution, the pH value of the solution and the ability to bind the etched alloy components into soluble Compounds,

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The known method of chemical etching (cleaning) surfaces of heat; energy equipment in a solution containing aggloni hydroxide, Trilon B and sodium nitrate 1.

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However, this method is unsuitable for etching the surface of manganese-copper alloys, since the product is not etched, its surface is dark, oxidized.

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The closest to the invention is a method of chemical etching of products from copper and its alloys, which includes processing in an aqueous solution containing ammonium hydroxide

30 and hydrogen peroxide. 2 This method is used in metallography to detect the microstructure of metals and alloys by chemical etching. With the ECHO of metals in the specified solvent, after 5 s, an etchant begins to instantaneously heat up and emit, which does not allow obtaining the active surface of the product, which is necessary for creating durable electroplating coatings. The aim of the invention is to increase the adhesion of electroplated coatings with a base of manganese-copper alloys. This goal is achieved by the fact that in the method of etching parts from copper containing alloys, including processing in an aqueous solution containing ammonium hydroxide and hydrogen peroxide, the treatment is carried out electrochemically at an anodic density of 1-5 A / dm with additional introduction of ethylene diamine tetraacetate into the solution .acids (Trilon B) with tracendem. the ratio of components: Trilon B, g19-150 Ammonium hydroxide, ml 62.5-500 Hydrogen peroxide, ml 62.5-500 Water, lUto 1 Heat treated {quenching at 870 ° С and tempering at) parts made of an alloy containing 75 % manganese and 25% copper (sheet material, 1.2 mm thick or 1.5 mm wire with the surface to be coated 5 cm) are degreased in an alkaline solution containing, g / l: caustic sodium carbonate 6. 30 Sodium phosphate trisubstituted 30 at 70 ° C for 15 minutes, washed in tap water with a 2-3-fold dipping, chemically etched in concentrated nitric acid 2-3 times by dipping, washed in running water, electrochemically etched in a solution containing: Trilon B, g19-150 Ammonium hydroxide, ml 62.5-50 Hydrogen peroxide, ml 62.5-50 Water, dDo 1 at a pH of f 7.5, room temperature. And anode density of 1-5 A / dm for 10-180 s, wash in tap water by 2-3-fold dipping. In a freshly prepared solution of Trilon B, ammonium hydroxide and hydrogen peroxide can be etched chemically. Electroplated coatings are applied to the parts treated in this way, then they are washed in tap water with a 2–3-fold color and dried. Electroplating coatings are applied from an alkaline electrolyte that does not contain halide ions, for example, the application of cadmium coatings, is carried out in an electrolyte containing, g / l: cadmium oxide 40 lmmonium sulfate 2b Thiourea 3 Dextrin 3 trilon B60 Ammonium hydroxide To pH at room temperature and current density O, 5 A / dm for 30 min, the deposition of zinc coatings is carried out in an electrolyte containing, g / l: zinc oxide25 sodium hydroxide 170 Trilon B50 UrotropinO 5, at pH 10, current density 1 A / dm for 30 min, and the deposition of copper coatings lead to electrol It contains, g / l: Copper sulfate55 Sodium pyrophosphate 240 Potassium nitrate 20 at pH-8, current density 1 A / dm for 30 minutes. Trilon B is a complexing agent that binds the Mn ions reduced by hydrogen peroxide and removes them from the sphere of the reaction. The ammonia solution (25%), on the one hand, is also a complex forming agent, and on the other hand, it creates the necessary alkaline medium and increases the solubility of trilon B. To achieve the desired effect it succeeds only in an alkaline medium, but necessarily in the presence of NH ions The results of etching in examples 1-4 are presented in the table. The adhesion strength of the coating to the base metal is verified by applying a grid of intersecting scratches and repeated bending until the specimen is destroyed. The etching solution for etching a manganese-copper alloy based on Trilon B, hydrogen peroxide and ammonia is easily adjusted by adding ammonia or hydrogen peroxide solution. When the solution is saturated with manganese and copper ions, the solution can be easily regenerated. Electrolytic insufflation of the latter at the cathode. Thus, the invention makes it possible to obtain strongly adhered galvanic coatings on manganese products in o-copper alloys. Coating of parts made of manganese-copper alloys is dictated by the need to carry out the processes of soldering, welding, and also to protect the alloy from corrosion. Coating with high adhesion to manganese-copper alloys is about (a reliable electrical contact, and, accordingly, makes it possible to use these alloys in automatic releases. Composition of the solution

ical switches instead of bimetal. Thanks to such a replacement, the cost of the releasers decreases by 30-40%.

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Claims (1)

Claim The method of etching parts made of copper-50 containing alloys, mainly manganese-copper alloys, including processing in an aqueous solution containing ammonium hydroxide and a hydrogen census, distinguishing. - 55 with the fact that, in order to increase the adhesion of galvanic coatings with a base made of manganese-copper alloys, the treatment is carried out electrochemically at an anode current density of 1-5 A / dm * s until an additional addition of ethylene diamine tetraacetic acid to the disodium salt (Trilon B) in the following ratio of components: Trilon B, g Ammonium hydroxide, ml Hydrogen peroxide, ml Water, l 19-150 62.5-500 62.5-500 to 1