RU2169794C1 - Method of cleaning metal surfaces from deposits - Google Patents

Abstract

FIELD: cleaning external and internal surfaces of hollow parts, for example, units and parts of engines from deposits. SUBSTANCE: method includes two- stage treatment of surfaces: at first stage, part is kept in aqueous solution containing 0.25 to 0.50 mole/g of H₂SO₄ and 0.05 to 0.1 mole/g of Na₂SO₃; at second stage, part is subjected to ultrasonic treatment through heating in aqueous solution containing 10 to 20 g/l of NaOH, 2.5 to 5.0 g/l of surfactants and 2 to g/l of hydroxy ethylidene diphosphonic acid. EFFECT: enhanced efficiency of cleaning external surfaces; reduction of time required for cleaning internal surfaces. 6 cl, 1 ex

Description

 The invention relates to the cleaning of deposits of external and internal surfaces of metal hollow parts, for example, parts, assemblies and assemblies of engines, including turbine rotor blades made of heat-resistant nickel-based alloys with an oxide-resistant coating on the outer surface, as well as other similar equipment.

 A known method in which to clean the surface of metal parts is used by immersion in a solution of oxalic acid with simultaneous exposure to ultrasound (SU 208821 A, 1968, C 23 G 1/02).

 The disadvantage of this method is the insufficient degree of cleaning of the surfaces of the parts.

 A known method in which to clean the surface of metal products is carried out in two stages: first in an alkaline solution of potassium permanganate with a ratio of caustic alkali to potassium permanganate equal to 1: 2, followed by treatment in a 15-20% aqueous solution of oxalic acid ( SU 261862 A, 1970, C 23 G 1/14).

 The disadvantage of this method is the insufficient degree of purification of metal surfaces from deposits.

 The prototype of the invention is a method for cleaning metal surfaces from deposits, including a two-stage treatment of the external and internal surfaces of metal hollow parts - in one, the first stage - an aqueous solution of alkali and in the second - 45-55% solution of nitric acid with the addition of sulfonated polydimethyl diallylammonium chloride and sodium polyamine sulfonate (RU 2036980 A, 1991, C 23 G 1/06)).

 The disadvantages of the method are the insufficient degree of cleaning of the outer surfaces of the parts and the low speed of cleaning the inner surfaces of the parts.

 The invention solves the problem of improving the cleaning efficiency of external surfaces and accelerating the cleaning of the internal surfaces of parts.

The specified technical result is achieved as follows. The method of cleaning deposits of external and internal surfaces of metal hollow parts includes a two-stage surface treatment - at one stage with an aqueous alkaline solution and at the other with an acid solution with additives. The difference between the method is that in the first stage, the part is kept in an aqueous solution containing 0.25-0.50 mol / L H ₂ SO ₄ and 0.05-0.1 mol / L Na ₂ SO ₃ , and in the second stages carry out ultrasonic treatment of the part when heated in an aqueous solution containing 10-20 g / l NaOH, 2.5-5.0 g / l surfactants and 2-3 g / l hydroxyethylidene diphosphonic acid.

 The optimal time for the first stage of processing is 48 hours, and the second stage of processing is one hour.

The optimal temperature range for heating the solution in the second stage is 60-65 ^o C.

 In special cases, the implementation of the method at the second stage of processing, the ultrasonic emitter is located directly above the cavities of the parts at a distance of 10-20 mm from them.

 Preliminary aging of metal hollow parts in a solution of sulfuric acid containing sodium sulfite leads to the efficient dissolution of deposits on the external surfaces of the parts, and also leads to an acceleration of the cleaning process of the internal surfaces of parts during ultrasonic treatment of parts in an alkaline solution.

The method of cleaning from deposits of external and internal surfaces of metal hollow parts includes a two-stage surface treatment. In the first stage, the part is kept in an aqueous solution containing 0.25-0.50 mol / L H _S SO ₄ and 0.05-0.1 mol / L Na ₂ SO ₃ . The optimal time for the first stage of processing is 48 hours.

At the second stage of processing, ultrasonic treatment of metal parts is carried out when heated in an aqueous solution containing 10-20 g / l NaOH, 2.5-5.0 g / l surfactant and 2-3 g / l hydroxyethylidene diphosphonic acid. The optimal time for the second stage of processing is one hour. In the second stage, the solution is heated in the optimal temperature range of 60-65 ^o C, and the ultrasonic emitter is located directly above the cavities of the parts at a distance of 10-20 mm from them. If there are axial and side holes in the part, ultrasonic radiation is carried out first above the axial hole, and then from the side of the side holes.

Example. The rotor blade of a high-pressure turbine was cleaned, containing internal cavities of a layered configuration and made of heat-resistant nickel-based alloys with an oxide-resistant coating on the outer surface, which had been in operation for several months and contained contaminants on the inner and outer surfaces. At the first stage of blade processing, starting from the content of 0.25 mol / L H ₂ SO ₄ and 0.05 mol / L Na ₂ SO ₃ in the aqueous solution, the degree of purification from deposits on the external surfaces began to increase, with the content of 0.50 mol / l of H ₂ SO ₄ and 0.1 mol / l of Na ₂ SO ₃ achieved the greatest effect, and with a further increase in the content of these components remained practically unchanged. The optimal time for the first stage of processing was 48 hours.

 After that, the blade was washed with water, in particular distilled, and proceeded to the second stage of processing.

In the second stage, ultrasonic treatment of the scapula in an aqueous alkali solution was carried out with heating. Starting from the content in the aqueous solution of 10 g / l NaOH, 2.5 g / l surfactant and 2 g / l hydroxyethylidene diphosphonic acid, the degree of purification from deposits on the internal surfaces began to increase, with the content of 20 g / l NaOH, 5.0 g / l surfactant and 3 g / l hydroxyethylidene diphosphonic acid achieved the greatest effect, and with a further increase in the content of these components in the solution remained practically unchanged. With the indicated quantitative range of the content of components in the solution, it was sufficient to carry out the second stage of processing for one hour. In the second stage, the solution was heated in the optimal temperature range equal to 60-65 ^o C. The ultrasonic emitter was placed directly above the cavity of the blade at a distance of 10-20 mm from them. Moreover, ultrasonic radiation was carried out first over the axial hole, and then from the side of the side holes. The degree of cleaning of the blade from deposits was determined by weighing it

Claims (6)

1. A method of cleaning from deposits of external and internal surfaces of metal hollow parts, including a two-stage surface treatment - in one stage, an aqueous alkaline solution and the other - an aqueous acid solution with additives, characterized in that at the first stage the part is kept in an aqueous solution containing 0 , 25 - 0.50 mol / L H ₂ SO ₄ and 0.05 - 0.1 mol / L Na ₂ SO ₃ , and in the second stage, ultrasonic treatment of the part is carried out when heated in an aqueous solution containing 10 - 20 g / L NaOH, 2.5 - 5.0 g / l of surfactants and 2 - 3 g / l of oxyethylidend ifosphonic acid.  2. The method according to claim 1, characterized in that the first stage of processing is carried out within 48 hours  3. The method according to claim 1, characterized in that the second stage of processing is carried out for one hour. 4. The method according to claim 1, characterized in that in the second stage the heating is carried out to 60 - 65 ^o C.  5. The method according to claim 1, characterized in that in the second stage, the ultrasonic emitter is located directly above the cavities of the parts at a distance of 10 to 20 mm from them.  6. The method according to claim 1, characterized in that in the presence of axial and side holes in the part, ultrasonic radiation is carried out first over the axial hole, and then from the side of the side holes.