SU1108143A1 - Solution for electrochemical polishing of high-chromium alloys - Google Patents

Abstract

SOLUTION FOR ELECTROCHEMICAL POLISHING OF HIGH-CHROME ALLOYS. containing sulfuric acid, an organic additive and water, characterized in that, with only the process intensification and an increase in the working capacity of the solution, it contains as an organic additive proteolytic enzymes in combination with ortho-nitrobenzoic acid in the following ratio of components, May. %: Sulfuric acid75-85 Orgo-nitrobenzoic acid0.5-0.6 Proteolytic enzymes0.05-0.06 WaterEverything Else with S (L

Description

00

with

The invention relates to the electrochemical machining of metals, in particular to the polishing of high-chromium alloys such as 40xNU, 4bHNM, 47xHM-VI.

Solutions are known for electrochemical polishing of high-alloyed chromium steels based on sulfuric and phosphoric acids with additions of organic acids, as well as glucose, dextrin, methyl alcohol, pyridine, quinoline, furfural 1.

However, they do not provide high-quality polishing of high-chromium alloys, since the surface is coated with a matte passive film during processing. In addition, a long treatment time is characteristic for these solutions.

A known electrolyte based on sulfuric and phosphoric acids with the addition of ethanol and alkali metal salts of sulfo carboxylic acids of Cu-Co fractions for electrochemical polishing of chromium-containing steels 2.

However, this electrolyte does not allow to obtain a high-quality surface when polishing high-chromium alloys, since traces of the solution are present on the surface.

Closest to the proposed technical essence and the achieved effect is a solution for electrochemical polishing of high-alloyed nickel-chromium steels containing sulfuric and citric acids.

This solution provides high-quality polishing of high-chromium alloys 3.

However, for the polishing process in this electrolyte, a longer processing time is characteristic, and the solution is of low working capacity.

The purpose of the invention is to intensify the process and increase the efficiency of the solution.

This goal is achieved by the fact that the solution for electrochemical polishing of high-chromium alloys containing sulfuric acid, an organic additive and water, as an organic additive contains proteolytic enzymes in combination with ortho-nitrobenzoic acid with the following ratio of components, May / O:

Sulfuric acid75-85

Orgo-Nitrobenzoin

acid0.5-0.6

Proteolytic enzymes 0.05-0.06 Water Else

The electropolishing process is carried out at 30 ° C, anodic current density of 220-250 A / dm and a polishing time of 30-40 s.

Proteolytic enzymes are classified as hydrogas enzymes, manufactured by industry according to TU 59-100-76, TU 49-522-79.

0 This solution is prepared as follows.

The required amount of sulfuric acid is poured into water, cooled to 40 ° C, then the required amount of orgo-nitrobenzoic acid and the proteolytic enzyme is dissolved, the solution is cooled to room temperature and stirred. The solution prepared in this way is brought to the desired volume with water.

The composition of the solution is

Q optimal. With a decrease or increase in the content of the components of the solution, there is an increase in the processing time and a decrease in the efficiency of the solution while simultaneously increasing the current density and the temperature of the electrolyte.

5 Studies were performed on samples.

wire 0.5 mm alloy 40xNU length 50 mm. The initial surface of the samples: the height of asperities Ng of 1.05 µm, the reflectivity - 53%.

Samples are treated to

0 the same surface: the height of asperities Rz of 0.2-0.27 microns, reflectivity of 89-94%.

In tab. 1 shows the composition of the solutions illustrating the invention.

Comparative test results

are shown in table 2.

As can be seen from Table 2, the solution with the addition of only orgo-nitrobenzoic acid (solution 7) or only the proteolytic enzyme (solution 8) has a low working capacity and a low polishing rate. Only the joint introduction into the solution of the polishing of orgo-nitrobenzoic acid and proteolytic enzymes makes it possible to increase the working capacity of the solution and the rate of polishing.

5 Thus, the proposed electrolyte makes it possible to intensify the process of electrolytic polishing by 1.8-2.5 times while simultaneously reducing the current density by 18-27%, increasing the efficiency of the solution by 2.7-2.85 times, and also improve working conditions by reducing gassing.

Table 1

Sulfuric acid 70 75 80 85 85

0.4 0.5 0.55 0.6 0.6 0.7 0.6

0.04 0.05

Note. In all examples, the water content is up to 100%.

0.02

0.05

0.02

0.055 0, 06 0.02 0.07

37

Table 2 80 80 80 22

Claims (1)

A SOLUTION FOR ELECTROCHEMICAL POLISHING OF HIGH CHROME ALLOYS, containing sulfuric acid, an organic additive and water, characterized in that, in order to intensify the process and increase the working capacity of the solution, it contains proteolytic enzymes in combination with ortho-nitrobenzoic acid in the following ratio of components, May. %: Sulfuric acid 75-85 Ortho-nitrobenzoic acid 0.5-0.6 Proteolytic enzymes 0.05-0.06 Water Rest FROM