SU981464A1 - Solution for electrochemical polishing of carbon steel products - Google Patents

Description

one

The invention relates to the electrochemical machining of metals, in particular to the polishing of carbon steel products (Art. 4O Art. 5O) and a surface protective and decorative surface finish of products can be used.

Solutions are known for high-quality electrochemical polishing of carbon steel in a mixture of phosphoric and sulfuric acids with the addition of various acid corrosion inhibitors lj and 2.

However, they have a disadvantage, of which the most significant are: the aggressiveness of the mixture of phosphoric and sulfuric acids is strong and the deficiency of most of the used inhibitors of acid corrosion, especially the inhibitor C-5, which is a by-product of a single production.

Closest to the proposed invention is a known solution of dp electrochemical polishing of carbon steel, containing

pyrophosphoric acid, potassium dichromate, acetamide and water 31%

This solution ensures short processing time and high quality polishing.

However, it contains a highly toxic Chromium compound (VJ). In addition, operations for the disposal of chromium (Vt) - containing solutions are very time consuming and costly. An exception to the composition of solutions for polishing zfom (N1) -containing compounds is an important factor in order to save scarce heavy metals.

. The purpose of the invention is to improve working conditions while maintaining high quality polishing.

This goal is achieved by the fact that the solution containing pyrophosphate ions and the organic additive additionally contains phosphoric acid, and as the source of the pyrophosphate ions and organic additive is potassium pyrophosphate and etipenediamine in the following ratio of components, g / l:

Pyrophosphate Kaln 650-70O

Phosphoric acid 60О-65О Ethylene diamine 5-7

The process of electropolishing is carried out at a temperature of from 60 to 7 ° C, an anodic current density of 35 to 55 A / dm, and a polishing time of 2 to 5 minutes. The ratio of the anodic and cathodic surfaces is 2: 1.

The use of potassium pyrophosphate in combination with phosphoric acid accelerates the process of electropolishing carbon steel products. The presence of ethylenediamine in the solution makes it possible to avoid etching and sludge formation on the surface of the parts, thereby improving the quality of polishing.

This solution is prepared as follows.

The required amount of potassium pyrophosphate is dissolved in small portions in a small amount of water (water to salt weight ratio 1: 3), continuously stirring and cooling the solution, until a dense homogeneous mass is obtained. Then the required amount of phosphoric acid and ethylenediamine is added to the resulting solution with unapplied cooling and stirring. The solution prepared in this way is brought to the desired volume with water. The resulting solution is completely transparent, has the viscosity of a liquid vegetable oil, and in the process, the color of the solution turns green.

The specified composition of the solution is optimal. With a decrease in the content of the components of the solution, a deterioration in the quality of the polishing of the carbon steel surface, up to etching, is observed. An increase in the concentration of the components in the solution does not reflect on the quality of the polishing; however, despite this, a greater concentration of the components should not be used. First, when the concentration of potassium pyrophosphate in the solution is higher than 7OO g / l, the solution becomes very viscous, to decrease its viscosity, it is necessary to increase the temperature of the electropolishing process to 95-100 ° C, which will make the solution unstable. Due to the evaporation of water, phosphate salts are observed to precipitate from the crystal solution. Secondly, an increase in the process temperature and the concentration of components in the solution (including phosphoric acid and ethylene diamine) in this case leads to an unjustified increase in energy and material costs, since a similar effect is achieved even with a significantly lower content of components in the pactpope.

The table presents examples of which the invention is illustrated.

Note. The numerator shows the data for C t 40,

denominator - Art. 5O.

Before electropolishing, the molds are sandblasted, after which a metrological toH is carried out to (clear the surface roughness parameters.

Thus, the invention allows for preserving high quality popv-. improve labor conditions (by eliminating the toxic chromium compound), as well as reduce the complexity of the process of disposal of wastewater.

F

the invention

about rmu l and

A solution for electrochemical polishing of carbon steel products containing: pyrophosphate ions and an organic additive, which is different

the fact that, in order to improve working conditions while maintaining high quality of lyophilization, it additionally contains phosphoric acid, and as a source of pyrophosphate ions and an organic additive, potassium pyrophosphate in ethvlendia | G when following the ratio of components, g / l:

Pyrophosphate Kaln 6.5O-7OO Phosphorus to slot 60O-65O Ethylenediamine 5-7

Sources of information taken into account in the examination

1. The copyright certificate of the USSR, No. 186822, class,. With 25 F 3/24, 1962.

2. USSR author's certificate number 745965, cl. C 25 F 3/24, 1978.

3. USSR author's certificate number 742493, cl. C 25 F 3/24, 1978.

Claims (1)

Claim 15 No. A solution for electrochemical polishing of carbon steel products containing pyrophosphate ions and an organic additive, characterized in that, in order to improve working conditions while maintaining high quality polishing, it additionally contains phosphoric acid, and as a source of pyrophosphate ions and organic additives - potassium pyrophosphate and ethylenediam ^ G 'in the following ratio of components tov, g / l: Potassium Pyrophosphate Phosphoric Acid Ethylenediamine 650-700 600-650 5-7