SU723425A1 - Electrolyte for polyshing monocrystals of molibdenum - Google Patents

Description

The invention relates to metallography, in particular to electrolytes for polishing thin sections for metallographic analysis.

'Known electrolyte for polishing and etching molybdenum and its alloys, containing, wt.%:

Sulfamic acid 5

Water The rest and- _{? 0} However, when polished in a known electrolyte, the surface of the polished sections of molybdenum single crystals turns out to be etched, rough and unsuitable for determining pores.

The aim of the invention is to develop an electrolyte composition that makes it possible to remove a deformed distorted surface layer from a molybdenum single crystal and obtain a polished thin-surface.

To achieve this goal, hydrogen peroxide was additionally introduced into the electrolyte containing sulfamic acid and water, in the following ratio, wt.%:

Sulfamic acid 4-5

Hydrogen Peroxide 3-10

Water Else

Hydrogen peroxide in the electrolyte is a catalyst for the reaction and eliminates the formation of molybdenum acids deposited in a dense film on the surface of the thin section of the molybdenum single crystal. With a decrease in the concentration of hydrogen peroxide of less than 3%, the surface of the thin section turns out to be etched; with an increase in the concentration of hydrogen peroxide of more than 10%, precipitates contaminate the surface of the thin section on the surface of single crystals. When the concentration of sulfamic acid is less than 4%, traces of processing are visible on the surface of the thin section; when the concentration of sulfamic acid is more than 5%, the surface of the thin section is eroded, uneven.

The polishing electrolyte is prepared as follows: 40-50 g of sulfamic acid are dissolved in 850-930 ml of distilled water, 10030 ml of a 30% hydrogen peroxide solution are added and mixed.

Example 1. Molybdenum single crystals with a diameter of 17 and 23 mm are polished in an electrolyte containing, wt%: sulfamic acid 5, hydrogen peroxide - 3, the rest is water. Stainless steel cathode, solution temperature 20-25 ° C, density ¹⁰ anode current 1-2 a / cm ^g . The duration of the process is 10 minutes. Then the single crystals are removed from the electrolyte, washed with water and again immersed for 1-2 minutes in an electrolyte containing concentrated * ⁵ sulfuric acid, at a current density of 1-2 a / cm ² . The sample is washed thoroughly with water and wiped with ethyl alcohol. Thus processed 30 single crystals. Polished surface of the section, the pores ²⁰ to chet- revealed.

Example 2. A single crystal of molybdenum with a diameter of 23 mm is subjected to polishing in an electrolyte containing, wt.%? hydrogen peroxide - 7, sulfamic acid ²⁵ - 4, the rest is water, and lead the process, as described in example 1.

Processed 45 single crystals of molybdenum. The polished surface is polished, the pores are clearly identified. ^thirty

Sample Molybdenum single crystals with a diameter of 17 mm are subjected to polishing in an electrolyte containing, wt.%: Hydrogen peroxide - 10, sulfamic acid - 5, the rest is water, and the process is carried out as described in example 1.

Processed 25 single crystals of molybdenum. The polished surface is polished, the pores are clearly identified.

The processing of thin sections of molybdenum single crystals in the proposed electrolyte eliminates the operation of mechanical grinding and polishing of single crystals. The cost of preparing the surface of thin sections of single crystals To determine the porosity is reduced by 7-8 times.

Claims (2)

The invention relates to metallography, in particular to electrolytes for polishing thin sections for metallographic analysis. A known electrolyte for polishing and etching molybdenum and its alloys, containing, in wt.%: Sulfamic acid5 WaterLends At the same time, when polished in a known electrolyte, the surface of thin sections of molybdenum single crystals is etched, rough and unsuitable for determining pores. The aim of the invention is to develop an electrolyte composition that allows the deformed distorted surface layer to be removed from the molybdenum single crystal and to obtain a polished surface of the polish. To achieve this goal, hydrogen is additionally introduced into the electrolyte containing sulfamic acid and water at the following ratio, wt.%: Sulfamic acid4-5 Hydrogen peroxide3-1О WaterOther Hydrogen peroxide in the electrolyte is a catalyst of the reaction and eliminates the formation of molybdic acids , settling in a dense film on the surface of thin section of molybdenum single crystal. With a decrease in the hydrogen peroxide concentration of less than 3%, the surface of the thin section becomes etched; with an increase in the concentration of hydrogen peroxide of more than 1 O%, precipitates fall on the surface of the single crystals, which pollute the surface of the thin section. When the concentration of sulfamic acid is less than 4%, traces of processing are visible on the surface of the thin section; if the concentration of sulfamic acid is greater than 5%, the surface of the thin section is eroded, uneven. The electrolyte for polishing is prepared as follows: 4O-50 g of sulfamic acid is dissolved in 850-930 ml of distilled water, 100 Oz ml of 30% hydrogen peroxide solution is added and mixed. Example I. Single crystals of molybdenum with a diameter of 17 and 23 mm are polished in an electrolyte containing, in wt.%: Sulfamic acid 5, hydrogen peroxide 3, and the rest is water. The cathode is made of stainless steel, the temperature of the solution is 2O-25 C, the density of the anodic current is 1-2 A / cm. The duration of the process 10 minutes. The monocrystals are then removed from the electrolyte, washed out and then immersed for 1-2 minutes in the electrolyte containing concentrated sulfuric acid at a current density of 1-2 a /. The sample is carefully taken with water and wiped with T-alcohol. Thus processed 30 single crystals. The surface of the schlifa is polished, the pores are clearly revealed. Example 2. A molybdenum single crystal with a diameter of 23 mm is polished in an electrolyte containing 7 by weight of hydrogen peroxide, 4 by sulfamic acid, and the rest is water, and the process is carried out as indicated in example I. 45 ms of ib-dena single crystals are processed. The polished surface of the polished, pores clearly revealed. Froze Molecular single crystals with a diameter of 17 mm are polished in an electrolyte containing, in wt.%: Hydrogen peroxide, 10, sulfamic acid, 5, the rest is water, and the process is carried out, as indicated in example I. 25 molybdenum single crystals are treated. The surface of the schlifa is polished, the pores are clearly developed. The processing of the molybdenum single crystal clips in the proposed electrolyte excludes the operation of mechanical grinding and polishing of single crystals. The cost of preparing the surface of thin sections of single crystals To determine the porosity is reduced by 7-8 times. The invention The electrolyte for polishing molybdenum monocrystals containing sulfamic acid and powder, characterized in that, in order to improve the quality of polishing, it additionally contains hydrogen peroxide in the following ratio of components, wt.%: Sulfamic acid4-5 Hydrogen peroxide Salt O Sources of information taken into consideration during the examination 1. Yu. P. Prisoner. You are a common structure of crystals. Metallurgists, M., 1974, p. 329-ZZO.