SU962339A1 - Method for electrolytically depositing osmium and iridium coatings - Google Patents

Description

The invention relates to electroplating, in particular to electrolytic deposition of osmium and iridium coatings, and can be used both to produce coatings with a thickness of 0.1100 µm and to obtain thin films and tin-targets from metal isotopes that are widely used in nuclear-physical and Other studies There is a method of electrolytic deposition of platinum in alkaline electrolyte using an intermittent current with a pulse duration of 20 min and a pause of 1-2 min, which provides coatings limited 10-20 µm LVj However, when using this method to precipitate osmium and iridium, it is not possible to obtain high-quality coatings — an amount of oxide or osmium hydroxide (iridium) is formed in 20 min of electrolysis, which is not enough to pause for one minute to dissolve, resulting in a process The electrodeposition of the material is stopped. The closest to the present invention is a method of electrolytic deposition of coatings by osmium and iridium in alkali and sulphamate electrolytes using direct current density. However, the known method is not sufficiently E04). So, when osmium is deposited from a sulphamate electrolyte, thin black non-metallic type c coatings with a low current output are obtained; you can get iridium coatings up to 3 µm from an alkaline electrolyte, but the alkaline electrolyte is aging very quickly. For osmium and iridium in both electrolytes, it is characteristic that it is impossible to obtain thick coatings (coating thickness is 0 µm) with a high current output (current output is only 0.5-2). In addition, the yield of metal in the film is low (up to 5%) 39 and the irrecoverable loss of precious metals is significant (up to 30). The purpose of the invention is to increase the current output and to obtain high quality coatings up to 100 microns thick. This goal is achieved by the fact that in the method of electrolytic deposition of coatings by osmium and iridium in alkaline and sulphamate electrolytes, the process is conducted with a discontinuous current of density 1, 6 A / dm with a pulse duration of 1-30 minutes and the ratio of the duration of pulses and pause between them 1 : 1 - 1: 2. The optimum current density is 1.5 A / dm. This mode of electrolysis in camps is based on studies of the current density ality. an increase in the current output of the metal, and with a further increase in the current density, the current output of the metal decreases dramatically. Thus, the maximum (C, 22%) current output of the metal is achieved only at a current density of 1.5 A / dm. decrease in current density to, C and increase to 1.6 A / d t to reduce the current output of the metal n 5-10.0. The concentration of osmium and iridium in electrolyte is recommended 5.0-5.5 g / l. The basis for determining this concentration of metal in the electrolyte was data on the current output of the metal. that an increase in the metal concentration by a factor of 2 (10.011, 0 g / l) leads to a decrease in the metal yield in the current by a factor of 3. For example, the osmium output in the current using an electrolyte with a metal concentration of 5.5 g / l is 22% , and at 11.0 g / l - 1, +. The concentration of the metal in the electrolyte of 5.5 g / l is the limiting one, since it achieves the maximum current output of the metal. The basis for determining the pro. Duration of pulses 1-30 minutes are the following data. It has been established that if the pulse duration is less than 1 min, then the electrodeposition of the metal is not observed,. in the case where the pulse duration is more than 30 minutes, then 9 4 a non-metal type metal film is observed. The ratio of the duration of electrolysis (pulse) and interruption of electrolysis (pause) is also determined by the possibility of obtaining films of osmium and iridium of the metallic type. Only with a 1: 1 and 1: 2 pulse to pause ratio, metallic-type films are obtained, while with a 1: 3 and 1 ratio: nonmetallic type. During the current-free period, timely return to the electrolyte at the cathode is ensured. electrolysis of oxide and hydroxide of the deposited metal. As a result, a sharp decrease in the concentration of the deposited metal in the electrolyte is not observed and the stability of the electrolyte operation (up to the depletion of the electrolyte by the ions of the deposited metal) is ensured. Electrolytes of the following composition are used to precipitate osmium and iridium coatings, g: Osmium in the form of iridium (as or Na, gC1b) 5-5.5 Sulfamic acid 20 Potassium hydroxide (solution) Up to 1 To obtain an alkaline electrolyte of this composition, sulfamic acid is excluded . The temperature of both electrolytes is 5-7 ° C. The coatings are applied to copper, the anode is platinum. The anode at the same time serves as a stirrer, ensuring active mixing of the electrolyte. The electrodes are mutually perpendicular. Both electrolytes are stable in operation up to the depletion of the electrolyte by ions of the deposited metal. The proposed method allows to obtain opaque and glossy metal-type coatings with a thickness of 0.1100 microns (and above) with a metal yield of 90 film. In this case, the cathodic output of metal by current in alkali and sulphamate electrolytes is respectively 6-11 and 8-26%. To obtain foil targets, osmi films (iridium) with a thickness of 1–10 µm are separated from the substrate by chemical means. Table. 1 gives several examples of the proposed method (deposition of coatings in all examples is carried out at a current density of 1.5 A / dm--). In tab. Figure 2 shows the dependence of the osmi current output on the ratio of the duration of the pulses and the pause between them (similar results were obtained for iridium). As can be seen from Table 2, during the precipitation of osmium from a sulphamate electrolyte, the most efficient deposition process is observed when the ratio of the duration of the pulses and the pause between them is 1: 1 and 1: 2 (the duration of the pulses is 1-30 min), and during the precipitation from an alkaline electrolyte -1: 1 and the duration of the pulses 1-15 mi 96 94 and 1: 2, but with a pulse duration of 1-3 min. The irreversible loss of precious metals in the entire technological cycle of obtaining coatings, including the synthesis of four, osmium tetroxide (or compounds and iridium), the preparation of electrolyte, 3ne iT metal deposition is only up to 3. Thus, the invention allows a 13-fold increase in output metal current, 16 times - the output of the metal in the film ,. 10 times the loss of the drapes of Metals, and also allows you to get high quality coatings in a wide range of thicknesses. . T b i y 1 claim The method of electrolytic deposition of osmium and iridium coatings in alkaline and sulphamate electrolytes, characterized in that, in order to increase the current efficiency and to obtain high quality coatings up to 100 microns, the process is carried out with intermittent current density

9 96233910

1, 6 A / Dm with duration of metals. L., Mechanical Engineering, 1971

pulses 1-30 minutes and the ratio of pro-s. 77. the length of the pulse and pause between

do them 1: 1-1: 2.2. Popovich TN Electrodeposition

Sources of information, s irid. On Sat Electrochemical

Taken into account in the examination of deposition and the use of coatings dra1. Yampolsky A.M., Electrolytic and rare metals. Khar

some sedimentation of noble and redkites, 1972, p. 78-98.

Claims (1)

Claim The method of electrolytic deposition of coatings with osmium and iridium in alkaline and sulfamate electrolytes, characterized in that ^55, in order to increase the current efficiency and obtain high-quality coatings up to 100 microns thick, the process is conducted with an intermittent current density 962339 ¹⁰ 1.4-1.6 A / dm ² - with a pulse duration of 1-30 minutes and a ratio of pulse duration and pause between them of 1: 1-1: 2.