SU583209A1 - Silver-plating electrolyte - Google Patents

Description

one

The invention relates to the field of electroplating, in particular to the deposition of dull silver coatings.

It is known that silver coatings, which do not grow dull in the atmosphere of sulfur compounds and other corrosive media, can be obtained directly from silvering electrolyte. in the presence of electrolytically non-precipitated sulfate additives from aqueous solutions of metals, such as aluminum, beryllium and magnesium 1.

However, these additives give a positive effect only in the case of iodide and ferrocyanide electrolytes, since their pH (S-ai corresponds to the formation of aluminum hydroxides of beryllium and magnesium.

In this case, hydroxide particles are formed in the near-cathode space, they have a positive charge and are electrophoretically incorporated into the cathode sediment.

The principle of this method is unacceptable for cyanide electrolyte, the pH of which is usually very high (10-12). In this case, the hydroxides are formed in the volume of the electrolyte (a suspension is formed, a suspension), the particles have a negative charge and are not included in each precipitate.

The closest to the proposed invention in terms of the composition of the components is silvering electrolyte, containing -. craving silver ion- (metallic silver), potassium cyanide, potassium carbonate and mercaptobenzothiazole {2.

However, from such an electrolyte it is impossible to Jolk untouching shores now. cover

. In order to obtain non-tarnishing coatings, the proposed electrolyte additionally contains a substance selected from the group containing beryllium sulphate, aluminum T1H4 sulfate, beryllium chloride and aluminum chloride, and silver chloride 20 in the following ratio of components, g / l:

Silver chloride 33-40 Potassium cyanide 50-70 Potassium carbonate 20-50 Mercaptobenzothiazole 0.1-0.5 Substance selected from the group containing beryllium sulfate aluminum sulfate. beryllium chloride and alyumvn chloride 2–20 are settled and recommended to be carried out at a pH of 9 / 5–12 / 5 / temperature and a cathode current density of 1-2 A / dm Xyto cm is a copper or an anode - silver plates. Sulfate b or injected into the electrolyte in copic 5-10 f / n, aluminum sulphate 10-20 g / l, beryllium chloride 2-6 g / l, aluminum chloride 4-in g / l. Coating / obtained from digesh electrolyte (without mercaptobenzothiazole in the presence of chloride or metal sulphate does not possess tarnish resistance Metal sulfate is obtained by non-tarnishing coatings. The diffusivity of electrolytes per hour is 34%, the current efficiency is a deposition rate of 3050 µm / hour / microhardness 100120 kg / adl, Felicia wear during sample abrasion with a nickel counterbody is 15 r / cti (unsent in the electrolyte without metal salts - control 17 g / cm.) Solderability (Coatings remain longer than the control ones. After two months of storage of samples in natural conditions, the spreading area of the sample solder on the studied coatings is 38 mM and on the control 32 mm. The coatings are corrosion-resistant, have a strong load. Coupling with the base. ash and sulphate or chloride metaisha contributes to obtaining more resistant to darkening nnyh silver coatings.

The name of the additive introduced into the electulite, containing 25 g / l of silver chloride, 60 g / l

Mercaptobenzotnazole, g / l Beryllium sulfate, g / l Aluminum sulfate, g / l Beryllium chloride, g / l

Note:. The deposition process is carried out at pH 10.2, temperature 20 Q, density

current 1.5 / A / dm8 and duration of 15 min. Corrosion tests of i-coatings are carried out in a desiccator (volume l1 above the solution formed / added to 1 liter of water, 3 ml of co-hydrated hydrochloric acid and 2: saturated sodium sulfate solution. Time: experimentation 2 hours.

 The assessment of the degree of darkening of the coatings in the hydrogen sulfide atmosphere was carried out visually according to the standard system:

0- no change,

1- barely noticeable yellowish film,

2 - yelta film,.

3 - light brown film, 4-5 brown film.

Examples

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0.3

0.3 8

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Claims (1)

Formula of izvoretey Mercaptobeisotiazol, 5 Power saw svoreOre}), and containing silver, silver content, potassium cyanide, carbonate sulphate b illi, potassium and mercury-benzothyArp, o t l n-g aluminum sulphate, tea neither with the fact that, with the purpose of beryllium chloride, and radiation without bih coxFggy, oi do-chloride a; 1g "(| nni 2-20 Completely contains, in,,. from the group / containing sulfate B-Sources of infants; n4acin taken in rylli, aluminum sulphate, beryl chloride at the experiment ( LIA and aluminum chloride, and as non-I. Copyright witness The ionisation site of silver - silver chloride / 282878, cl. C 25 D 3/46, 16.12.68, and with the following ratio of components - 1972. : Comrade .. , , - .. V -, .. ;; -.v ...,;., ...; Silver chloride 33-40 .2, copyright certificate Potassium cyanide 50-70 168572, cl. C 25 D 3/46, 12.13.62, Potassium carbonate 20-501965. Uvezhestvo, selected