SU1224353A1 - Electrolyte for precipitating iron-nickel alloy coatings - Google Patents

Description

The invention relates to electroplating, in particular, to galvanoplastic deposition of iron-nickel alloys and can be applied in instrument engineering, radio engineering, engineering and other industrial sectors.

The aim of the invention is to increase the deposition rate and increase the iron content in the coating.

The deposition is carried out at a current density of 5-AO A / dm, a temperature of 20-40 C and a pH of 2.8-5.8.

The combined introduction of iron, nickel carbonate, and sulfosapicylic acid increases the total amount of ions of the discharging metals, which leads to an increase in the deposition rate. The speed also increases because. complex sulphosalicylic acid complexes with metal boron fluorides are also discharged at the cathode and contribute to the efficiency of the process.

The electroplating production of Fe – Ni alloys with an iron content of up to 95% with a high deposition rate becomes possible due to the stabilizing effect of the additives introduced. Sulfosalicylic acid prevents the precipitation of iron hydroxide due to the formation of a solid dissolved complex. Hardening of this complex also contributes to the process at a low temperature. With the joint introduction of nickel carbonate and sulfosalicylic acid, the buffer capacity of the solution increases, which allows maintaining the pH in the range of 2.8-5.8.

The introduction of metallic and carbonic nickel contributes to an increase in the concentration of discharging iron ions.

The introduction of an increased concentration of boric acid somewhat reduces the upper limit of the permissible values of current density. In the presence of boric acid, the electrolyte has practically no effect on glass, which allows accurate pH measurements by the glass electrode. The upper limit of the boric acid concentration in the electrolyte can be increased to 20 g / l (the limiting solubility of boric acid at 20 s). However, this increases the cost of the electrolyte, and the functional value of boric acid does not change

The quality of precipitation is not significantly improved. Using a nickel boron fluoride concentration of less than 43 g / l does not allow to work

at a current density of up to 40 A / dm j greater than 155 g / l is impractical because of the increased cost of electrolyte and the need to increase the working temperature up to 50 C. The optimal concentrations of iron boron fluoride (7-238 g / l) are due to the requirements for the doping interval and allow They produce alloys in a wide range of composition. Sodium lauryl sulfate is used

as an antipitting additive. When sodium lauryl sulfate concentration is less than 0.3 g / l, traces of pitting appear. A concentration of 0.5 l / g allows to obtain thick qualitative

sediments above this quality deteriorate.

The concentration of metallic iron and nickel carbonate is chosen so that the total concentration of metals does not exceed the optimum (70.58 g / l) necessary to intensify the process and extend the interval of the alloying element in the alloy to 95%, and also to maintain a constant excess of free sulfosalicylic acid 6 in an amount of 10.3 g / l, 18-141 g / l of sulfosalicylic acid are introduced into the electrolyte, but only 10.3 g / l of it is free

and the rest reacts with iron, nickel carbonate and other electrolyte components (borfluorides) to form complexes of simple and complex composition.

When sulfosalicylic acid is added to the electrolyte in an amount of less than 18 g / l, precipitation of the alloy has an uneven iron distribution, since there is no stabilization of the composition; when adding more than 141 g / l, irregular gloss appears on the sediments, which increases with increasing current density to 5 - 40 A / dm Further addition of sulfosalicylic acid leads to the appearance of dark bands due to electrolyte instability.

The electrolyte of the invention is prepared as follows.

Nickel boron fluoride and iron boron boron are obtained by dissolving nickel carbonate and iron powder in a 40% hydrogen boron fluoride solution

lots separately. Then, a solution of iron boron fluoride is poured into the nickel boron fluoride solution, boric acid, iron, nickel carbonate and sulfosalicylic acid, dissolved in a small amount of water, are added. The prepared electrolyte is processed at low current densities of 0.2-0.5 A / dm in order to remove impurities, filtered, sodium lauryl sulfate is added and the pH is adjusted with sulfosalicylic acid to the required values.

The table shows examples of electrolytes according to the invention and known.

As can be seen from the table, the electrolyte is functional at room temperature, the presence of an additional amount of iron in the electrolyte leads to an increase in the iron content in the sediments, and sulfosalicylic acid contributes to the complex formation which prevents the precipitation of iron (III) hydroxide, which leads to

Composition, g / l Nickel boron fluoride

200-250 -300 43

Iron boron fluoride 1-14 -450

Borna acid 8-no

Saccharin

1-no

Sodium lauryl sulfate

Iron metal

Nickel carbonate

Sulfosapicic acid

Electrodeposition Mode

pH

1-5

243534

to obtain high-quality precipitation during prolonged electrolysis. A small amount of free sulfosalicylic acid that has not reacted with

5 with iron and nickel carbonate, increases the buffer capacity of the solution, allowing electrolysis to be carried out at a high current density of up to 40 A / dm with a current efficiency of 98%. A high concentration of Qi qi metals allows to intensify the process.

As a result of the high electrical conductivity of the solution, it is possible to use high current densities with low

15 bath tension. The electrolyte according to the invention increases the speed of the deposition process by 2-4 times. in comparison with the known, it allows to obtain coatings with the thickness of SOA microns or more, improves the quality of precipitation by stabilizing the electrolyte, increases pro- The percentage content of the alloying element in the alloy is up to 95% and makes it possible to work without heating and moving the electrolyte.

67

93

155

238

59

23

3.5

Oi3 0.3 0.3 0.5

5.6

10 15

1.5 15.5 11.3 29.5

 8 68

79.4 141

5.8 3.5

3.5 2.8

Coating thickness

mm

0.02

results

Current output,% 10.2-96 -100 98

5800

5-35 -75.6 6.95

sixteen

Notes 1. An asterisk indicates optimal conditions.

2. The proposed electrolyte 3 - in comparable v; conditions where the iron content in the alloy is 35%.

Compiled by Yu.Pozdeeva Editor N Shvydka Tekhred O.Sopko Proofreader S.Shekmar

Order 1894/26 Circulation 615 Subscription VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d.

Branch PSh1 Patent, Uzhgorod, st. Project, 4

.Table continuation

0.3 0.3

0.3 0.3

98

5800

98 98 95.7 5800 5800 4000

59

35 5

Claims (1)

. ELECTROLYTE FOR LAYING COATINGS WITH AN IRON-NICKEL ALLOY, containing nickel and iron borofluorides, boric acid and sodium lauryl sulfate, characterized in that, in order to increase the deposition rate and increase the iron content in the coating, it contains nickel carbonate, sulfosalicylic acid and metallic (powder ) iron in the following ratio components, g / l: Nickel boron fluoride Iron boron fluoride Boric acid Sodium lauryl sulfate Metallic (powder) 43.0-155 238.0-7.0 3.0-3.5 0.3-0.5 iron 1-15 Q Nickel carbonate 1.5-29.5 SS Sulfo with alicylic ay £ L acid 18-141 W g s: e tnurik to to