SU471399A1 - Cadmium electrolyte - Google Patents

Description

I

This invention relates to the electrolytic deposition of metals.

A cadmium cyanide electrolyte is known, containing cadmium complex cyanide, free cyanide, alkali, and nickel and sodium sulphate salts.

The purpose of the invention is to reduce the hydrogenation of metals in the electrolysis process and to ensure the electrolyte self-regulation of cadmium ions.

For this, cadmium hydroxide is introduced into it in an amount exceeding its solubility (an excess of undissolved hydroxide is in the form of a precipitate at the bottom of the bath). The excess cadmium hydroxide present in the electrolyte binds to the CN anions, which are released when the Cd (CN) 4 complex anion is discharged and prevents the reduction of the cadmium salt concentration in the electrolyte. Thus, this electrolyte does not contain free CN anions. The proposed electrolyte contains, g / l: cadmium in the form of complex salt (CN) 4 35-95 caustic soda 5-15 sodium sulphate 40-60 nickel sulphate 0.5-1.5 cadmium hydroxide to saturation.

The electrolysis is carried out at a current density of 0.8-10 A / dm Cadmium anodes. The cadmium coating is light, fine crystalline. In the preparation of the electrolyte hydroxide

cadmium is introduced into it in the amount of 15-

35 g / l and added as it decreases

sediment at the bottom of the bath about once every two

week, in the amount of 35 g / l.

With cadmium plating in the proposed electrolyte at a current density of 2 a / dm, polished samples from EI-643 steel with a hardness of HRC 52 are not destroyed at a voltage of 135 kg / mm2, while in a known electrolyte containing free CN-, the same

specimens are destroyed within 2-5 minutes.

Subject invention

The cadmium-electrolyte containing cadmium in the form of complex cyanide salt, caustic soda, sodium sulphate and nickel sulphate, characterized in that, in order to reduce the hydrogenation of metals during the electrolysis process and to ensure electrolyte self-regulation of cadmium ions, more than its solubility, in the following ratio of components, g / l: cadmium in the form of (CN) 4 35-95

caustic soda 5-15

sodium sulfate 40-60

0.5-1.5

nickel sulphate to saturation. cadmium hydroxide