SU916612A1 - Cobalt-plating electrolyte - Google Patents

Description

The invention relates to electroplating, in particular to the electrolytic deposition of cobalt coatings. and can be used in those areas of technology in which the coating imposes high hardness and corrosion resistance in alkaline environments, for example in mechanical engineering, etc. Due to the various magnetic properties of cobalt coatings, the invention can be used in space and computer technology.

An alkaline electrolyte, cobalt containing cobalt sulphate, potassium pyrophosphate, potassium chloride, hydrazine hydrochloric acid and 1,4-butyndiode is known. The deposition process in this electrolyte is carried out at pH = 9.5- "10 and a temperature of 40 ° C with an asymmetric alternating current. Under these conditions, brilliant coatings are obtained, possessing a microdisciprometer [ί], which is boosted (up to 460 kg / mm ⁸ ).

2

However, the known electrolyte has rpdom deficiencies. The electrolyte is stable only at pH = 9.5–10.0, which is caused by the use of potassium formate as a complexing agent. Due to electrolyte instability at pH above 10, it is not possible to use high concentrations of cobalt sulfate, to expand the range of operating current densities and, consequently, to obtain cobalt coatings with greater hardness. Electrolyte instability in high alkaline regions also adversely affects the performance and time of operation of the electrolyte. High-quality cobalt coatings from a known electrolyte are obtained with increased

_Well temperature, which requires additional energy consumption for heating and worsens working conditions. The known electrolyte is monocomponent in composition, which leads to complication

3,916 (

preparation, analysis and correction. it, and also neutralization of sewage. It requires an additional device that provides the generation of asymmetric current.

The closest to the invention in terms of the composition of the components is the known cobalt electrolyte containing cobalt chloride, hexamethylenetetramine and chlorinated ammonium. Deposition is carried out at pH = 6-7temperature 18-25 C and Ka _g todnoy current density of 0.5-4.5 A / dm, coating deposition rate is 10-40 micrometers / h (2]. 1

However, the scattering ability of a known electrolyte is relatively low (25–30% according to Field’s method), the electrolyte is not stable enough, the anodes begin to overgrow with crystals of 2 soluble compounds after passing 4 Ah / l, shielding the working surface. In addition, the electrolyte operates in the relatively narrow “current density band ,, ,, 2

The purpose of the invention is to increase the scattering ability and stability of the electrolyte.

This goal is achieved by the fact that the electrolyte containing chlorine-> cobalt and the complexing agent additionally contains potassium hydroxide, and aminoacetic acid in the following ratio of components, _ g / l: ³ as the complex-forming agent

Cobalt chloride 95-140

Ami noks usa naya

acid 180-250

Potassium hydroxide 160-190 ₄

In addition, ¹ invention allows to expand the range of operating current densities to 15 A / dm ^g , which accordingly allows to increase the deposition rate to 78 μm / h. _#

The deposition process is recommended to be carried out at pH®9.5 ~ 13>, temperature 18-ZO * ⁸ C and current density 2-1 5 A / dm ^2. Using rolled, cast or electrolyte rolitic cobalt as a soluble anode . Coatings are applied to copper or brass. In the present invention, the use

> 12 4

iminoacetic acid, as a complexing agent, whose cobalt complexes are stable with its excessive content and high pH,

5 and carrying out the process in the low-temperature mode led to an increase in the stability of the electrolyte in the strongly alkaline region (to pH = 13.0). Due to electrolyte stability

In the strongly alkaline region, it became possible to use higher concentrations of the cobalt compound and increase the solubility of the cobalt anodes. The use of high concentrations of cobalt compound and soluble anodes ensured the expansion of the range of working current densities, due to which it became possible to purposefully approach

0 to the choice of electrodeposition conditions to obtain cobalt coatings with desired properties, for example, to increase the hardness of cobalt coatings, as well as to increase the electrolyte productivity and its operation time.

From the electrolyte at a speed of 1478 m / h and a current yield of 40-68% precipitated chalk _d semi-bright light kokristallicheskie coating microhardness of which is 440 565 kg / mm ^2.

The invention is illustrated by several examples presented in the table.

Thus, the invention allows to significantly increase the scattering ability of the electrolyte from 2530 to 41-59% (77-85% according to the method of Hering and Blum). Electrolyte stability at optimum pH values (12.1-13.2) is practically unlimited, anodes are active in a wide range of current densities (1-15 A / dm *). The possibility of carrying out the deposition of coatings at the maximum current density (10 or 15 A / dm) leads to the process being almost doubled.

An increase in the scattering ability and stability of the electrolyte, and the intensification of the process lead to an increase in the productivity of the process as a whole.

five

916612

6

--------------------, ----- The composition of the electrolyte, | g / l; mode and results Examples 3 theta electrolysis one one ι 1 one one 2 | one Hexahyloe Cobalt Chloride 95 1 19 140 Amino acetic acid lot 250 188 180 Potassium hydroxide 190 180 160 pH 9.5 13.0 12.1 about Temperature, C 18 24 thirty Current density, A / dm 3 2/15 five ten The deposition rate, micron / hour 14.0 42 78 Current output,% 57/41 68 67 Microhardness, kgf / mm ^ 510/557 440 560 Coupling with the base Kink at Clutch Breaking strip bend on the good sample ki 90 * with before it after 3 codfish ma basics zag.zagiba • sediment at 90 ^s without sedimentation Electrolytic stability that, a'chas / l After a day Virtually unlimited ki falls out not soluble sediment on Scattering ability,% according to the method of Field 41 59 55

In example 1, the numerator presents data obtained at a current density of 2 A / dm®, in the denominator - 15 A / dm ² ·.

Claims (1)

Electrolyte claims, it further contains Cobalt electrolyte, potassium hydroxide, and as containing cobalt chloride and complexing complex ⁵⁵ - aminoexcoobenzelgel, a distinctive acid with the following ratio to me so that, in order to increase the distribution of ingredients, g '/ l: cohesive ability and stability Cobalt Chloride 95-140 7 916612 eight Aminoacetic acid 180-250 Potassium GiDroxide 160-190