SU857305A1 - Palladium-plating electrolyte - Google Patents

Description

The invention relates to gsvanostegii, in particular to electrolytic deposition of palladium coatings. Amino chloride electrolytes Psshladirovany to obtain matte coatings containing palladium chloride, hydrochloric acid, ammonium ammonium sulphate and ammonium chloride are known. In order to obtain low-porous coatings, sodium i and 2 sulfite are injected into this electrolyte. However, these electrolytes do not allow to obtain high-quality Peshladium coatings with a thickness of more than 5 microns. The closest in technical grade is an electrolyte containing palladium chloride, ammonium sulphate, ammonium hydroxide and saccharin t-. From a known electrolyte with a temperature of 20–60 ° C, in the cathode range of current densities from 0.6 to 1.6 A / dm, it is possible to precipitate semi-bright precipitates with thicknesses up to 20 µm, the minimum porosity of which is 0.05%. gloss does not exceed 18S. At thicknesses greater than 20 microns, microcracks occur in the coatings. The purpose of the invention is to improve the quality of the coating. The goal is achieved by the fact that the known electrolyte additionally contains 1-carboxy-8-heptadecene-11-yl disodium salt of sulfuric acid in the following ratio of components, g / l: palladium chloride 20-40 ArFtonium sulfate 20-30 Sol per acid15-25 Hydroxide ammonium 150-250 saccharin 0.2-0.6 disodium salt 1-ka boxy-8-heptadecen-11-yl sulfuric acid 0.2-0.4 The said compound (C aH-NajOg S) is a surfactant, good wetting palls and non-degradable during electrolysis. The introduction of this compound into the palladating electrolyte makes it possible to obtain thick-layer (up to 60 µm), high-bleed, almost porous coatings. The deposition process is recommended by wire 1t at an electrolyte pH of 8.5-9.5, cathode current density from 0.5 to 2.0 A / dm, temperature 15-30 ° C, preferably the anodic region is separated from

cathode microporous diaphragm. In this case, the solution connecting 150 ml / l of a 25% ammonia solution and 30 g / l of ammonium sulfate can serve as an anolyte. The correction of the electrolyte is made by adding the calculated amount of diamine dichloropalladium after decreasing its concentration by 30%. Ammonium sulphate is added once per month. The content of saccharin and disodium salt of 1-carboxy-8-heptadecen-11-yl sulfuric acid is not analyzed, and these additives are replenished after passing every 3.0 A | H / l electrolyte in the amount of O, 1 g / l and 0, 4 g / l, respectively. AgF1aac is added periodically after reducing the pH of the electrolyte to 8.5 in the amount of BeB, providing a pH value of 9.2. .

For one liter of electrolyte in a 1.5 liter conical round-bottomed flask containing 200 MP of a 4% hydrochloric acid solution, 30 g of palladium chloride are dissolved when heated. 500 ml of 10% ammonia is gradually poured into this solution, heated to temperature. First, a pink precipitate is formed, which, with stirring, is completely dissolved for one hour. Then, 20 g of ammonium sulfate is added to the electrolyte. Then, 0.5 g of saccharin and 15 ml of a 2% solution of 1-carboxy-8-heptalene-11-yl disodium salt of sulfuric acid dissolved in 0.1 N are added. potassium hydroxide solution. Dilute with distilled water to a volume of 1 l and get ready palladium electrolyte.

Electrolyte is stable in time. When it is stored in open form, the pH of the electrolyte is slowly lowered; its primary value is easily achieved by introducing a small amount of ammonia into the electrolyte.

The invention is illustrated by the examples given in the table,

Disodium salt of 1-carboxy-8-heptadec-11-yl sulfuric acid

electrolyte pH

2 current density. A / dm

Temperature, ° С

Current output,%

Deposition rate

µm / h

Reflectance,%

Maximum thickness of the cover until the appearance of M1 | 1 crack, microns

Porosity,%

g Hardness, kg / mm

Electrolyte dispersing ability according to Heathleys,%

0.2 0.2 0.3 0.4 0.4

8.5 9.0 9.0 9.3 9.5

0.5 1.0 1.5 1.5 2.0

18-25 18-25 28-25 18-25 18-25

98.5 98.7 98.4 98.5 98

32

25

25

sixteen

58

55 To 60 To 65 To 64

60 60

55 60 60

0.01 0.015

0.01 0.01 0.02

340 340

330 340 340

77

76

80

Claims (1)

75 As can be seen from tajelitsa, the presence of only one organic additive in the electrolyte (saccharin or does not give a maximum increase in the parameters of pallas (European coatings. Only with the joint presence of both additives, the coating parameters reach {Extreme values, namely: one can precipitate three times more hundred-layer coatings, the degree of gloss increases more than threefold, and the porosity decreases fivefold compared to coatings obtained from known electrolytes. The coatings have strong adhesion to the base metal (honey , silver) - they are not exfoliated by repeated bending to kink. The coatings obtained in the proposed electrolyte can be widely used in the electronic and instrument-making industries for electrical contacts, as well as for protecting reflectors and mirrors from corrosion. The coatings in the proposed electrolyte are much less porous, their protective ability is increased, and, thus, it is possible to increase the service life of electrical contacts or other parts by several times. burnt palladium. Claims of Electrolyte palladium containing palladium chloride, 1mmonium sulphate, hydrochloric acid, hydroxide. ammonium and saccharin, which has the effect that, in order to improve the quality of the coating, it additionally contains 1-carboxy-8-hept disodium salt of sulfuric acid in the following ratio of components, g / l: -Palladium chloride Ammonium sulphate Salt of acid 150-250 Ammonium hydroxide 0.2-0.6 Saccharin Disodium salt 1-carboxy-8-heptadecen-11-yl sulfuric 0.2-0.4 acid Sources of information, pr these are taken into account during the examination 1. IT Patent 1 31500 € 5, class 204-47, 1964, Patent IT 04076599, class 204-47, 3. USSR author's certificate 224243, class. C 25 D 3/56, 1967.