Method of coating

 

The invention relates to mechanical engineering and can be used in the aviation and energy turbine construction for protection of parts operating at high temperatures, including large parts of hot turbine section. Conduct preliminary surface treatment of parts of the gas turbine engine. Applied three-layer heat-shielding coating. Thermal method is applied the first layer of an alloy based on Nickel. Method slip technology put the second layer containing aluminum. Carry out drying at a temperature of 350oC for 30-60 min Spend vacuum annealing. Process surface coating clitoris.com. Thermal method put the third ceramic layer. Spend finishing the surface of the third ceramic layer vibroshlifovalnye. Then carry out a vacuum heat treatment details. The invention allows to increase service life of large parts. You do not need expensive equipment and the cost of coverage is reduced more than twice. 6 C.p. f-crystals, 1 table.

The invention relates to mechanical engineering and can be used in the aviation and energy) the x components of the hot section of the gas turbine (combustion chamber, the heating pipes, and so on).

Known method of applying a multilayer coating plasma thermal spray method, where the first layer is applied coating system Ni-Cr-Al-Y, as well as a second layer ceramics [1].

The coatings obtained according to the method, have a small share (no more than 300 hours at a temperature of1050oC) due to the detachment of the ceramic layer. The cause of delamination is accelerated oxidation of the surface of the first layer and the low strength of the oxide film formed on the boundary of the metal and ceramic layers of the coating.

The closest analogue, taken as a prototype, is a method of coating a turbine blade comprising an abrasive-liquid handling and processing clitoris.com, application of a heat-resistant coating composition, wt.%: chromium 16-18, aluminum 11-13, cobalt 7-9, yttrium of 0.25-0.5, Nickel - other, of a thickness of 15-30 μm by vacuum-plasma technologies for high energy, then the same method is applied a second layer of a thickness of 20-40 μm, containing the following components, wt.%: Nickel 13-16, yttrium 1,5-1,8, aluminum - rest, then spend diffusion vacuum annealing, vibrosieve and the flapper clitoris.com. Then put the third of ceramices>

The known method does not allow to apply the coating on parts of complex configuration, as well as large parts, with the shaded areas of the working surface, as well as application methods used in the prototype, provide directional deposition from a plasma or steam flow of the coating material, fixed in space.

An object of the invention is the possibility of coating the components with complex configurations and large parts while maintaining high quality turf.

The goal of the project is achieved by the fact that in the proposed method of coating involving pre-treatment of the workpiece surface, the first layer of the heat-resistant coating of an alloy based on Nickel, apply a second layer containing aluminum, conducting vacuum diffusion annealing, the surface treatment coating clitoris.com, application of the third ceramic layer and finishing the coated parts, the first and third layers of coating applied thermal method, and the second layer by the method of slip technology, and before vacuum diffusion annealing carry out the drying of the second layer at a temperature of 350

The application of thermal spray method and slip technology provides the ability to coat parts with complex configurations and large parts shaded surface (inner surface) due to the possibility of moving in space flow of the coating material or slip through the torch movement (thermal spraying) or spray (slip cover). When vacuum diffusion annealing the first and second layers of coating on the surface of the part is melting the second (slip) a layer containing aluminum, resulting in the bonding of these layers with the formation of a dense diffusion aluminide coatings based on refractory phase NiAl (who of metal connective layer of thermal protection (heat-shielding cover includes a connecting layer, as well as the external ceramic layer). The connecting layer obtained after vacuum diffusion annealing, contains ~ 26-30% (wt.%) aluminum and silicon and yttrium, which ensures that during operation thermal barrier coatings on the border with the ceramic coating, the formation of a strong oxide layer having a low growth rate and density of ~ 100%, which in General allows to obtain a high heat resistance, heat-resistance coatings and resource the coated parts.

The invention is illustrated in the example.

Example. The coating is applied to the samples and in situ parts of the heat-resistant sheet Nickel alloy residence permit 145.

Flat samples and a sheet of heat-resistant alloy is subjected to pretreatment under a coating (degreasing, sandblasting clipmarks.com 25A on sandblasting installation) to remove oxides and other contaminants and provide a rough surface. After the preparatory processing item thermal method (plasma spraying on the installation of the UPA-ZV) put the first layer of heat-resistant coatings of Nickel alloy containing Cr (20.5 per cent);
With (4,27%);
Al (12.3 per cent);
Y (0,43%),
thickness of 30, 65, 100 μm. Coating system Ni-Co-Cr-A is Tavi system MeCrAlY, where Me-Ni or Ni-Co is known. These alloys can be further doped elements such as TA, Re, Hf, W, S, Si and other Specific composition of the first coating layer is selected depending on the material of the workpiece in such a way as to match thermal coefficient of linear expansion (TCLE) in the field of operating temperatures of the base material (workpiece) with a linear thermal expansion coefficient of the coating material of the first layer.

Then on the item put the second layer of slurry of the following composition, wt. %::
The fine powder on the basis of Al - 40-60
Alumacraft binding - Rest
To improve the quality slip coating of fine powder on the basis of Al impose additional Si is (0.5-15) or Si (0,5-15) and Y (0,1-1,3), and the alloying powder Y conduct if the content of Y in the first coating layer is low (<0.2%) or Y is not part of the first coating layer. The presence of silicon in the slurry contributes metallothermic reactions occurring during vacuum diffusion annealing the first and second coating layers, and slagging unnecessary elements included in the slurry, and yttrium provides improved adhesion of the oxide film at the boundary between the metal and ceramic layers of the coating. While Si and Y can introduce is based on Al. Slip coating applied by brush or spray gun (depending on the availability of large areas of the product to be coated grade WITH 6A when the pressure of compressed air 3-5 ATI one or two layers with a total thickness of 50-100 μm, followed by drying of the slip layer in air atmosphere in a furnace at a temperature of 350oWith aged 30-60 min and the temperature rise for 1.5-3 hours This drying mode allows you to completely remove the water from the slip layer regardless of the size and weight of parts that contributes to obtaining high-quality coverage.

Next item is subjected to diffusion vacuum annealing at a temperature of 1000oWith over 4-4,5 hours to obtain diffusion aluminide layer. In the process of vacuum annealing is the seal of the first coating layer filling the open porosity inherent thermal spray coating formed during annealing of the intermetallic-based-phase (NiAl) containing 26-30% aluminum. When the content of aluminum inphase and alloying it with chromium and yttrium from the first layer and the silicon from the slip, or silicon and yttrium from the slip coating has high heat resistance and does not affect onnot samples and parts processed by clipmarks.com 25A 5P-6P to remove toxins from the second layer on the basis of the slip, the appearance of bright metal surface and create roughness5-6. Then the part with the cover blown clean with compressed air from the remnants of the oxide to ensure the best adhesion of the ceramic layer.

To clean the sample surface and parts applied thermal method of the third ceramic layer of the following composition, wt.%:
Y2About3- 7
ZrO2- Rest
After applying a layer of ceramic samples and the coated parts are subjected to the finishing processing (ceramic layer on the samples had a thickness of 30, 150, 300 μm). As a finishing hold fibrolipoma the surface of the ceramic layer to obtain a surface roughness6-7, and then vacuum heat treatment of the coated parts at a temperature of 1000-1050oC for 1-2 hours

Samples were obtained from a sheet of heat-resistant alloy VG with coatings of different thickness and composition of the slurry was tested for heat resistance and thermal stability. Comparative characteristics of the samples with coating, obtained by the proposed method and the method prototype, shown in the table.

From the example, the second heat-resistance when tested in the relaxed atmosphere of the furnace in air at 1150oS and high thermal stability during hard test cycle (see PP. 1, 2, 3, table). At the minimum thicknesses of the coating layers and the minimum content of Si and Y in the slip layer (sample 1) the coating has a resistance of more than 60 cycles and the resistance at the level of 725 hours At the maximum thicknesses of the coating layers and the maximum content of Si and Y in the slip layer (sample 3) the coating has a resistance at the level of 750 hours and a temperature of 56 cycles. Sample 2 having the average composition of the slip and the average thickness of the coating layers have properties on the prototype (sample 4), which uses ceramic columnar structure having high heat resistance. On the sample surface with a coating obtained by the method prototype, after thermal Cycling test (60 cycles) defects not detected, and after testing resistance at 1150oWith over 800 hours were observed slight (5% of the total surface) chipped ceramic coating layer (third layer).

The proposed method can be applied to large parts of complex configuration-coating with high heat resistance and heat resistance, which allows more than two-fold increase resource otvetstvennye" does not require expensive equipment. Cost of coverage obtained by the proposed method, more than two times lower than the cost of the coatings obtained in a known manner.

Sources of information
1. Kolymitsev P. T. Gas corrosion and strength Nickel alloys. - M.: metallurgy, 1984, S. 169-170.

2. RF patent 2078148.


Claims

1. The method of applying a coating on parts of the gas turbine engine, comprising pre-processing of the workpiece surface, the first layer of the heat-resistant coating of an alloy based on Nickel, apply a second layer containing aluminum, conducting vacuum diffusion annealing, the surface treatment coating clitoris.com, application of the third ceramic layer and finishing the coated parts, characterized in that the first and third layers of coating applied thermal method, and the second layer by the method of slip technology.

2. The method according to p. 1, wherein before carrying out vacuum diffusion annealing carry out the drying of the second layer at a temperature of 350oC for 30-60 minutes

3. The method according to p. 1 or 2, characterized in that as a finishing treatment using vibrosieve surface of the third ceramic with the fact, the second layer is applied from a slurry, the following chemical composition, wt.%:
The fine powder on the basis of aluminum - 40-60
Alumacraft binding - Rest
5. The method according to p. 4, characterized in that the fine powder on the aluminum base has a composition, wt.%:
Silicon is 0.5 - 15
Aluminum - Rest
6. The method according to p. 5, wherein the fine powder on the aluminum base further comprises yttrium 0.1 to 1.3 wt.%.

7. The method according to any of paragraphs.1-6, characterized in that the thickness of the first coating layer is 30-100 μm, the total thickness of the first and second layers after vacuum diffusion annealing - 30-110 mm, the thickness of the third layer 30-300 μm.

 

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FIELD: metallurgy, namely chemical and heat treatment of refractory alloys, possibly used for applying protective coatings onto blades of gas-turbine engines.

SUBSTANCE: method comprises steps of applying onto inner and outer surfaces of parts diffusion aluminide coating in circulating gaseous medium; applying coating in low-active system at relation of reaction surfaces Fн/Fo = 0.3 - 0.7, where Fн - total surface of parts to be coated; Fo - total surface of saturating mixture; then applying onto outer surfaces of parts cladding coating, namely MeCrAlY, where Me - Ni, Co, NiCo by ion-plasma process or electron beam evaporation in vacuum.

EFFECT: improved fire and corrosion resistance of coating, increased resource of blades of gas-turbine engine.

1 cl, 1 ex, 1 tbl

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