RU2365466C1 - Method for protection of blade surface - Google Patents

Abstract

FIELD: technological processes, metal working.

SUBSTANCE: invention is related to machine building, in particular, to surface protection in repair of cooled and non-cooled blades of stationary power sets of aviation gas-turbine engines by method of hot isostatic pressing. Prior to performance of hot isostatic pressing, suspension is applied onto blade surface based on microslice powders from fused corundum with different granularity and organosilicon binder. Drying is carried out with further annealing, and protective ceramic shell is obtained.

EFFECT: improved quality of blades repair due to provision of blade contact surfaces protection against oxidation at operation of hot isostatic pressing.

5 cl, 2 dwg, 1 ex

Description

The invention relates to the field of repair, in particular to the repair of cooled and uncooled blades of stationary power plants of aircraft gas turbine engines (GTE) by hot isostatic pressing (GUI).

A known method of protecting the surface of the turbine blades of gas turbine engines made of heat-resistant nickel alloys during ISU (RU No. 2184178, C23F 17/00, publ. June 27, 2002). According to the specified method, to diffuse the surface of the blades, a diffusion protective coating of a certain thickness is applied to their outer and inner surfaces. However, the application of such a coating on the blade leads to a change in the geometric dimensions and, accordingly, the mechanical properties of the surface layer, which requires subsequent machining, which leads to an increase in the complexity and cost of repairs.

A known method of protecting the surface of the blades during the GUI, selected as the closest analogue, including the use of a powder of refractory oxide powders with a metal filler of metals that react with oxygen contained in the atmosphere of the gas bath (RU No. 2252110, B22F 3/15, publ. May 20, 2005). The disadvantage of this method is the high gas permeability of the powder filling, which does not protect the contact surfaces of the blades during the GUI.

The technical result to which the invention is directed is to improve the quality of repair of the blades by protecting the contact surfaces of the blades from oxidation during GUI operations.

The specified technical result is achieved by the fact that in the proposed method of protecting the surface of the scapula, before suspension is applied, a suspension is applied to the surface of the scapula based on microsilica powders from electrocorundum with different grain sizes and organosilicon binder, then drying is carried out, followed by firing, to obtain a protective ceramic shell.

As an organosilicon binder, LUDOX-SK can be used. The use of this binder allows you to provide a more durable protective ceramic shell.

In this case, the suspension can be applied layer by layer, performing drying between the operations of applying the layers at a temperature of up to 100 ° C. Drying at higher temperatures is impractical, since water will boil, which can lead to the formation of porosity of the protective ceramic shell.

Firing can be done at temperatures up to 1000 ° C. Firing at higher temperatures can lead to oxidation of the surface layer of the blade.

After performing the ISU operation, the protective ceramic shell can be removed in the molten potassium bifluoride and / or aqueous alkali solution.

Removing the protective ceramic shell in the molten potassium bifluoride and / or aqueous alkali solution will allow a better cleaning of the surface of the scapula.

This technical solution allows to improve the quality of repair of the blades by ensuring the protection of the contact surfaces of the blades from oxidation during GUI operations.

The invention is illustrated by drawings.

Figure 1 shows the structure of the surface layer of the Christmas tree element of the shank of the blade of the theater of operations after working out the resource on the engine.

Figure 2 shows the structure of the surface layer of the Christmas tree element of the shank of the blade of the fuel assembly from the alloy ZhS6U-VI after repair in accordance with the claimed method.

An example implementation of the claimed invention.

Repair of a set of working blades of a high-pressure turbine (TVD) from the ZhS6U-VI alloy after working out the resource on the engine was performed with the protection of the contact surfaces of the Christmas tree element of the shank of the blade according to the claimed method.

Before performing the repair, an analysis was made of the state of the contact surfaces of the Christmas tree element of the shank of the blade. As a result of the studies, it was found that on the contact surfaces of the Christmas tree element of the shank of the blade, the alloy is depleted as a result of long-term operation of the blades under high temperatures and the metal layer is hardened up to 5 μm thick as a result of fretting.

To protect the contact surfaces of the Christmas tree element of the shank of the blade, a suspension was made.

For example, based on 3 micro-grinding powders made of electrocorundum with different grain sizes in the following ratio (wt.%):

electrocorundum F36 35 electrocorundum F60 40 electrocorundum F220 25

and organosilicon binder LUDOX-SK in proportion to the weight of the mixture of electrocorundum powders 1: 3,5. The composition was mixed until a homogeneous suspension.

This suspension was applied to the surface of the Christmas tree element of the shank of the blade and after drying the blades at a temperature of 25 ° C for 8 hours at a relative humidity of 40%, the protective ceramic shell was fired according to the regime of 1000 ° C for 8 hours.

The blades protected by the above method have passed

- GUI operation according to the mode - temperature 1210 ° С, pressure 160 MPa, holding time 2.5 hours;

- removal of the protective ceramic shell by processing in a melt potassium bifluoride;

- preparation of the surface of the blades for applying a protective heat-resistant coating;

- applying a heat-resistant protective coating on the outer surface of the pen and the inner surface of the cooled channels by the method of two-stage powder chromoalitization with the protection of the Christmas tree element of the shank of the blades with metal caps.

The application of the claimed method allowed to increase the efficiency and reliability of the GTE blades, as well as reduce the cost of repairs by protecting the contact surfaces of the Christmas tree element of the shank of the blades using a protective ceramic shell based on electrocorundum, which prevented the oxidation of contact surfaces during the GUI operation (Fig. 2) .

Claims (5)

1. A method of protecting the surface of a turbine blade during hot isostatic pressing (GUI), characterized in that before carrying out hot isostatic pressing, a suspension is applied to the surface of the blade using microsilica powders from electrocorundum with different grain sizes and organosilicon binder, and then drying is carried out followed by firing to obtain protective ceramic shell. 2. The method according to claim 1, characterized in that LUDOX-SK is used as an organosilicon binder. 3. The method according to claim 1, characterized in that the suspension is applied in layers with the execution between the operations of applying the layers of drying at temperatures up to 100 ° C. 4. The method according to any one of claims 1 to 3, characterized in that the firing is carried out at a temperature of up to 1000 ° C. 5. The method according to claim 1, characterized in that after the operation of the ISU, the protective ceramic shell is removed in the molten potassium bifluoride and / or aqueous alkali solution.

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