SU586206A1 - Solution for electrochemical cleaning of a metal surface - Google Patents

Description

one

This invention relates to the electrochemical treatment of metallic surfaces, in particular, to the cleaning of gas turbine engines (GTE).

During the operation of aircraft engines on the surface of parts, in particular turbine blades, high-temperature deposits are formed, which are a mixture of sparingly soluble metal oxides and fuel combustion products.

These deposits, accumulating in the cavities of the surface defects of the blades, prevent the detection of these defects under inspection, osus1, as a result of capillary pH 1 1M 1 by means of flaw detection.

A known solution for the electrochemical treatment of a metal surface, containing sodium hydroxide, complexing agent (ethnlandnamine tetraacetic acid) and water 1. The solution also contains sodium monogentonate, sodium alkylaryl sulphonate, disubstituted sodium phosphate, sodium metasilicate and sodium cyanide.

Surface cleaning with this composition is carried out at a temperature of 60-100 ° C and an anode current density of 30 A / dm.

The disadvantage of this composition and method of its use is the incomplete removal of high-temperature deposits (degree of cleaning 50-60% for 2 hours of processing), which does not provide high quality preparatory parts of the GTE parts before testing with capillary methods of flaw detection; multicomponent composition, including toxic sodium cyanide; use of ethylenediaminetetraacetic acid as a complexing agent, having a small complex-forming form 1, its ability in an alkaline medium but not related to transition metals.

The proposed electrolyte differs from the well-known in that, in order to increase the degree of surface cleaning, as a complex, it is created by an applicant (or a substance selected from the group consisting of the sodium salt of oxnethylidene diphosphonic, dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxyacetate, or dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxyacetate, or dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxyacetate, or dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxyacetate, or dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxyacetate, or dethylenetriamine pentaacetic acid or 2-hydroxyethylimine dihydroxycarboxylic acid, dethylenetriamine pentaacetic acid or 2-hydroxyethyliminoacetic acid, or :

Caustic sodium 10-30

Substance selected from

group including

hydroxyethylidene diphosphonic sodium,

Diethylentia Minna-Acetic or 2-hydroxyethylminoduukeia

acids 1-5

WaterEverything

The cleaning process is recommended to be carried out at a temperature of 70-90 ° C, anode current density of 5-15 A / dm for 0.5-2.0 hours.

The solution is prepared by serially dissolving caustic soda in water (100-300 g), a complexing agent (15-50 g) and adjusting the volume of the solution to 1 l with water.

Example 1. A 1 dm piece after degreasing is placed in a solution containing caustic soda (700 g), sodium nitrite (200 g) and water (1 l), at a temperature of 130-140 ° C, kept in this solution for 0, 5-1.0 hours for loosened high temperature deposits.

Then, the part is washed in hot water (50-70 ° C) by repeated immersion and electrochemical treatment is carried out in 1 liter of a solution containing 200 g of sodium hydroxide, 30 g of hydroxyethylidene diphosphonic acid sodium salt and water (up to 1 l) at anodic current density 10 A / dm for 0.5 hours at a temperature of 75-80 ° C.

After washing the part in hot water, the operation of clarification in an ultrasonic bath of type UZV-15M 10 is carried out with a solution of hydrochloric acid for 3-5 minutes at a temperature of 15-30 ° C.

The degree of surface cleaning of the part is 90-95%.

Example 2. The purification process is carried out similarly to the process described in Example 1, using sodium salt of diethylenetriamine pentaacetic acid as the complexing agent in an amount of 30 g / l at 5 A / dm for 2 hours at a temperature.

The degree of surface cleaning of the part is 90-95%.

Example 3. The purification process is carried out similarly to the process described in Example 1, using the sodium salt of 2-hydroxyethyl-L-1-thioacetic acid as the complexing agent in an amount of 30 g / l at 15 A / dm for 1 hour at the same time 70 ° C.

The degree of surface cleaning of the part is 90-95%.

The proposed solution has the following advantages compared with the prototype;

- high degree of removal of high-temperature deposits (up to 90-98%);

-orostota composition;

-the absence of toxic components in it.

Ultimately, the use of sodium salts of the above-mentioned acids as a complexing agent, which possess a high complexing ability in an alkaline environment, provides a higher degree of detection of defects and corrosion-specific flaw detection methods.

Claims (1)

Invention Formula A solution for electrochemical treatment of metal surfaces, containing sodium hydroxide, complexing agent, and water, about tlichayuschiys in that, in order to increase the degree of surface treatment, as komnleksoobrazovatel it contains a substance selected from the group consisting of sodium salt oksietilidendifosfonovoy, dietilentriamiipentauksusnoy or 2-oksietiliminodiuksusioy acid in the following ratio of components, weight. %: Caustic soda 10-30 Substance selected from the group comprising sodium hydroxyethylidene diphosphonic, diethylenetriaminepentaacetic or 2-hydroxyethylimine diacetic acid1-5 WaterEverything Sources of information taken into account in the examination I. Patent of France No. 1473125, cl. From 23f,. 1967.