CN116445852A - A processing technology of aluminum-chromium co-dripping coating for working blade of gas turbine - Google Patents

Abstract

The invention relates to a processing technology of an aluminum-chromium co-permeation coating of a gas turbine working blade, which comprises the steps of firstly cleaning the surface of the blade, carrying out dry sand blasting, then preparing a co-permeation agent by 50-55 parts of aluminum oxide, 35-45 parts of aluminum powder, 5-10 parts of chromium powder and 0.3-0.5 part of ammonia chloride according to parts by weight, adopting an embedding method to complete co-permeation in an aluminum-permeation furnace which is vacuumized, heating to 1000-1050 ℃, preserving heat for 8-10h, adding an alternating current electric field in the heat preservation process, and carrying out sand blasting treatment to complete the preparation of the aluminum-chromium co-permeation coating. The preparation method provided by the invention is simple, the steps are easy to operate, the thickness of the prepared aluminum-chromium co-permeation coating is 50.61-51.76 mu m, and the co-permeation coating is uniform in thickness and has excellent oxidation resistance.

Description

A Processing Technology of Al-Cr Co-dripping Coating for Working Blade of Gas Turbine

technical field

The invention belongs to the technical field of preparation of aero-engines and gas turbines, and in particular relates to a preparation process of an aluminum-chromium co-infiltration coating.

Background technique

In the field of aviation manufacturing, aluminum-chromium co-infiltration is a common metal infiltration process, which is mainly used to improve the high-temperature oxidation resistance of steel and heat-resistant alloys. Due to the temperature of the working environment, aero-engine blades and their parts require good high-temperature oxidation resistance and high-temperature corrosion resistance. Therefore, surface coatings are required on aero-engine blades to improve thermal corrosion performance and high-temperature oxidation resistance. However, in the preparation process of the existing aluminum-chromium co-dipping coating, the coating is not uniform and the coating thickness is difficult to control.

Contents of the invention

The present invention aims to solve the problem that the thickness uniformity of the coating is not easy to control and the oxidation resistance is weak when the existing aluminum-chromium co-infiltration process is used to treat aircraft engine blades, and an aluminum-chromium co-infiltration coating for gas turbine working blades is provided. processing technology.

The present invention adopts the following technical scheme: a processing technology of an aluminum-chromium co-dipping coating for a working blade of a gas turbine, comprising the following steps:

(1) Pretreatment: use metal cleaning agent to treat the oil pollution on the surface of the working blade of the gas turbine, and then use corundum sand to perform dry sandblasting on the surface of the blade. The sandblasting time is 0.25-0.5 hours, until the surface of the blade is uniform gray;

(2) Preparation of co-penetrating agent: each component is calculated in parts by weight: 50-55 parts of aluminum oxide, 35-45 parts of aluminum powder, 5-10 parts of chromium powder, 0.3-0.5 part of ammonium chloride, and the above-mentioned composition The co-penetration agent prepared by mixing evenly;

(3) Embedding: Put the prepared co-infiltration agent into the tooling, embed the leaves in the co-infiltration agent to ensure that the leaves are completely covered, the bottom of the falcon teeth of the blades is 2-2.5cm away from the bottom of the tooling, and place the embedded tooling in an aluminizing furnace;

(4) Vacuuming: pump the vacuum in the aluminizing furnace to -0.1MPa, and feed in argon to return the air pressure in the aluminizing furnace to positive pressure, and repeat this for 3 times to complete the vacuuming;

(5) Heating program: raise the temperature in the aluminizing furnace from room temperature to 1020°C within 2-2.5 hours, and keep it warm for 8-10 hours. During the process of coating embedding and heat preservation, add an alternating electric field to promote the uniform completion of the coating surface co-infiltration;

(6) After the co-infiltration is completed, the blades are released from the furnace after cooling down. When the cooling of the powder and parts in the tooling is lower than 50°C, take out the blades to cool and clean them;

(7) After the blades are weighed, sand cleaning is carried out by blowing, and the aluminum-chromium co-infiltration coating is prepared.

Further, during the dry sandblasting, the blasting pressure is 0.1-0.3Mpa, the blasting angle is 70-90°, and the blasting distance is 200-300mm.

Further, the particles of the corundum sand are ≥130 mesh.

Further, in the step (6), argon gas is introduced to cool down the temperature until the temperature in the furnace is lower than 200°C and the furnace is released.

Further, in the step (2), put the alumina, chromium powder, and aluminum powder into an oven and heat them to 200-250°C for 0.5-0.8 hours. After the heat preservation is completed, put the dried powder and ammonium chloride into the mixing feeder, take it out after stirring for 0.5-0.8 hours.

Further, the current of the alternating electric field in the step (5) is 2A, and the voltage is 50-90V.

Advantage of the present invention is specifically as follows:

The preparation method of the invention is simple, the steps are easy to operate, the thickness of the prepared aluminum-chromium co-infiltration agent coating is uniform, and the aluminum and chromium in the surface layer of the prepared aluminum-chromium co-infiltration layer react with oxygen to form a dense and stable aluminum/chromium composite oxide The protective film prevents the contact between the blade and oxygen, greatly reducing the oxidation rate of the blade. Adding an alternating electric field during the co-infiltration and heat preservation process can effectively promote the formation of the co-infiltration coating. The adjustment of the electric field strength can achieve an effective effect on the thickness of the coating. regulation.

Description of drawings

Fig. 1 is a schematic diagram of the metallographic results of the Al-Cr coating in three embodiments of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, the specific implementation manners of the present invention will be further described below in conjunction with specific drawings.

Example 1:

A processing method of an aluminum-chromium co-dripping coating for a working blade of a gas turbine:

(1) Pretreatment: use metal cleaning agent to clean the surface of the working blades of the gas turbine, and then use ≥130 mesh corundum sand to perform dry sandblasting on the surface of the blades. During dry sandblasting, the sandblasting pressure is 0.1Mpa, and the sandblasting angle is 90°, the sandblasting distance is 300mm, and the sandblasting treatment time is 0.25h;

(2) Co-infiltration agent preparation: get 51.6 parts of alumina by weight, 40 parts of aluminum powder, 8 parts of chromium, 0.4 part of ammonium chloride and mix evenly, put alumina, chromium powder, aluminum powder into oven and heat to Keep warm at 200°C for 0.5 hours. After the heat preservation is completed, put the dried powder and ammonium chloride into the mixer, stir for 0.5 hours and take it out to prepare a uniformly mixed infiltration agent;

(3) Embedding: put the prepared co-infiltration agent into the tooling, embed the blades in the co-infiltration agent, the bottom of the blade falcon tooth is 2cm away from the bottom of the tooling, and install the embedded tooling in the aluminizing furnace;

(4) Vacuuming: the vacuum in the aluminizing furnace is evacuated to -0.1MPa, and argon gas is introduced to make the air pressure in the aluminizing furnace return to positive pressure, and this is repeated 3 times to complete the vacuuming;

(5) Heating program: raise the temperature in the aluminizing furnace from room temperature to 1020°C in 2 hours, keep it warm for 8 hours, and add an AC electric field during the coating embedding and heat preservation process to promote the uniform infiltration of the coating surface. Among them, the AC electric field Current is 2A, voltage is 90V;

(6) Introduce argon gas to cool the temperature. When the temperature in the furnace is lower than 200°C, the blades are taken out of the furnace. When the cooling of the powder and parts in the tooling is lower than 50°C, the blades are removed and cleaned;

(7) The blade and the test piece were weighed respectively, cleaned by sand blasting, and the Al-Cr co-infiltrated coating was prepared.

Example 2:

A processing method of an aluminum-chromium co-dripping coating for a working blade of a gas turbine:

(1) Pretreatment: use metal cleaning agent to treat the oil pollution on the surface of the working blade of the gas turbine, and then use corundum sand to dry the surface of the blade. The sandblasting time is 0.5 hours, until the surface of the blade is uniform gray, dry sandblasting , the blasting pressure is 0.1Mpa, the blasting angle is 90°, and the blasting distance is 200mm;

(2) Preparation of co-infiltration agent: each component is counted in parts by weight, 50 parts of alumina, 45 parts of aluminum powder, 5 parts of chromium powder, 0.3 part of ammonium chloride, put alumina, chromium powder and aluminum powder into Heat the oven to 250°C and keep it warm for 0.5 hours. After the heat preservation is completed, put the dried powder and ammonium chloride into the mixer, take it out after stirring for 0.00 hours, and mix the above components evenly to prepare the co-penetration agent;

(3) Embedding: Put the prepared co-infiltration agent into the tooling, embed the leaves in the co-infiltration agent to ensure that the leaves are completely covered, the bottom of the blade falcon teeth is 2.5cm away from the bottom of the tooling, and the embedded tooling device is placed in the infiltration in the aluminum furnace;

(4) Vacuuming: pump the vacuum in the aluminizing furnace to -0.1MPa, and feed in argon gas to make the air pressure in the aluminizing furnace return to positive pressure, and repeat this for 3 times to complete the vacuuming;

(5) Heating program: raise the temperature in the aluminizing furnace from room temperature to 1000°C within 2.5 hours, and keep it warm for 8 hours. During the process of coating embedding and heat preservation, add an AC electric field to promote the uniform co-infiltration of the coating surface. The current of the electric field is 2A, and the voltage is 50-90V;

(6) After the co-infiltration is completed, the blades are released from the furnace after cooling down. When the cooling of the powder and parts in the tooling is lower than 50°C, take out the blades to cool and clean them;

(7) After the blade is weighed, it is cleaned by sand blowing, and the aluminum-chromium co-infiltration coating is prepared.

Example 3:

A processing method of an aluminum-chromium co-dripping coating for a working blade of a gas turbine:

(1) Pretreatment: use metal cleaning agent to treat the oil pollution on the surface of the working blade of the gas turbine, and then use corundum sand to dry the surface of the blade. The sandblasting time is 0.5 hours, until the surface of the blade is uniform gray, dry sandblasting , the blasting pressure is 0.3Mpa, the blasting angle is 70°, and the blasting distance is 300mm;

(2) Preparation of co-infiltration agent: each component is counted in parts by weight, 55 parts of aluminum oxide, 35 parts of aluminum powder, 10 parts of chromium powder, 0.5 part of ammonium chloride, put aluminum oxide, chromium powder and aluminum powder into Heat the oven to 220°C and keep it warm for 0.6 hours. After the heat preservation is completed, put the dried powder and ammonium chloride into the mixer, stir for 0.6 hours and take it out to prepare a uniformly mixed co-penetration agent;

(3) Embedding: Put the prepared co-infiltration agent into the tooling, embed the leaves in the co-infiltration agent to ensure that the leaves are completely covered, the bottom of the blade falcon teeth is 2.5cm away from the bottom of the tooling, and the embedded tooling device is placed in the infiltration in the aluminum furnace;

(4) Vacuuming: pump the vacuum in the aluminizing furnace to -0.1MPa, and feed in argon gas to make the air pressure in the aluminizing furnace return to positive pressure, and repeat this for 3 times to complete the vacuuming;

(5) Heating program: raise the temperature in the aluminizing furnace from room temperature to 1050°C within 2 hours, and keep it warm for 10 hours. During the process of coating embedding and heat preservation, add an AC electric field to promote the uniform co-infiltration of the coating surface. The current is 2A and the voltage is 90V;

(6) After the co-infiltration is completed, the blades are released from the furnace after cooling down. When the cooling of the powder and parts in the tooling is lower than 50°C, take out the blades to cool and clean them;

(7) After the blade is weighed, it is cleaned by sand blowing, and the aluminum-chromium co-infiltration coating is prepared.

Comparative example:

A processing method of an aluminum-chromium co-dripping coating for a working blade of a gas turbine:

(1) Pretreatment: use metal cleaning agent to treat the oil pollution on the surface of the working blade of the gas turbine, and then use corundum sand to dry the surface of the blade. The sandblasting time is 0.5 hours, until the surface of the blade is uniform gray, dry sandblasting , the blasting pressure is 0.3Mpa, the blasting angle is 70°, and the blasting distance is 300mm;

(2) The co-penetrating agent is aluminum chromizing agent with the brand name of HM102 from Hunan Xinghong New Material Technology Co., Ltd.;

(3) Embedding: Put the prepared co-infiltration agent into the tooling, embed the leaves in the co-infiltration agent to ensure that the leaves are completely covered, and the embedding depth is 2.5cm from the bottom of the tooling. in the aluminum furnace;

(4) Vacuuming: pump the vacuum in the aluminizing furnace to -0.1MPa, and feed in argon gas to make the air pressure in the aluminizing furnace return to positive pressure, and repeat this for 3 times to complete the vacuuming;

(5) Heating program: raise the temperature in the aluminizing furnace from room temperature to 1050°C within 2 hours, keep it warm for 10 hours, and complete the co-infiltration;

(6) After the co-infiltration is completed, the blades are released from the furnace after cooling down. When the cooling of the powder and parts in the tooling is lower than 50°C, take out the blades to cool and clean them;

(7) After the blade is weighed, it is cleaned by sand blowing, and the aluminum-chromium co-infiltration coating is prepared.

Detect the aluminum chromium co-dripping coating that above-mentioned embodiment 1-embodiment 3 prepares:

The test results are as follows:

(1) Coating thickness

Table 1 Thickness of Al-Cr coating on blade surface

Example 1 Example 2 Example 3 comparative example Coating thickness (μm) 50.61 51.76 50.59 20.8

As can be seen from the results in Table 1, the thickness of the Al-Cr co-infiltrated coating obtained by the preparation method of the present invention is higher than that of the comparative example, which shows that the proportioning ratio of the Al-Cr co-infiltrated agent of the present invention is reasonable and adopts an AC electric field to accelerate the deposition of the coating , so that the aluminum chromium in the co-penetration agent can better form a coating on the working blade of the gas turbine under the action of an alternating electric field, and the coating thickness is much higher than that of the comparative example.

(2) Microstructure of Al-Cr coating

Fig. 1 is the metallographic result of the Al-Cr co-infiltrated coating of Example 1-3, as can be seen from the figure, the Al-Cr co-infiltrated coating is divided into two parts, the outer layer area and the inner layer area, and the outer layer area contains the infiltration agent Impurities, the inner layer has a basalt structure, and the two-layer structure meets the requirements of the seepage layer structure in the technical requirements of the seepage layer. It can be seen from the figure that the co-infiltration coating on the blade surface is evenly distributed.

(3) Oxidation test

The blades in Examples 1-3 were kept in the air at 1100±10°C for 15 hours. After cooling, it was found that there were no oxidation and corrosion marks on the surface of the blades, and no delamination phenomenon occurred, and the whole was uniform gray. The coatings prepared in Invention Examples 1-3 have excellent oxidation resistance.

(4) Composition testing

The ratio of the content of aluminum and chromium in the co-infiltration coating on the blade surface in Examples 1-3 was measured, and the results are shown in Table 2.

Table 2 Table of Al-Cr content in Al-Cr coating on blade surface

As can be seen from the above table, the Al-Cr coating obtained by the method of the present invention has an aluminum content of 25.4-27.1% of the total coating mass in the surface layer, and 14.8-18.1% of the total coating mass in the inner layer. The content of aluminum in both the surface layer and the inner layer is higher than that of chromium. The co-drilling coating can provide enough aluminum atoms to form an aluminum oxide protective film. A small amount of chromium in the co-drilling coating can improve the peeling resistance of the aluminum oxide protective film. It can also form a chromium oxide protective film, and the composite protective film of aluminum oxide and chromium oxide can reduce the oxidation rate of the blade.

Claims (6)

1. A processing technology of an aluminum-chromium co-permeation coating of a gas turbine working blade is characterized by comprising the following steps of: the method comprises the following steps:

(1) Pretreatment: carrying out dry sand blasting on the surface of the gas turbine working blade by corundum sand after carrying out surface oil stain treatment on the gas turbine working blade by using a metal cleaning agent, wherein the sand blasting time is 0.25-0.5 hour until the surface of the blade is uniformly gray;

(2) Preparing a co-permeation agent: the components in parts by weight are as follows: 50-55 parts of aluminum oxide, 35-45 parts of aluminum powder, 5-10 parts of chromium powder and 0.3-0.5 part of ammonia chloride, and uniformly mixing the above components to prepare the co-permeation agent;

embedding: filling the prepared co-permeation agent into a fixture, embedding the blades into the co-permeation agent to ensure that the blades are completely covered, enabling the bottoms of the falcon teeth of the blades to be 2-2.5cm away from the bottoms of the fixture, and placing the embedded fixture into an aluminizing furnace;

(4) Vacuumizing: vacuumizing the aluminizing furnace to-0.1 MPa, introducing argon to make the air pressure in the aluminizing furnace return to positive pressure, and repeating the steps for 3 times to finish vacuumizing;

(5) Heating program: heating the temperature in the aluminizing furnace from room temperature to 1020 ℃ within 2-2.5h, preserving heat for 8-10h, and adding an alternating current electric field in the coating embedding heat preservation process to promote the uniform completion of co-permeation of the surface of the coating;

(6) After the co-infiltration is finished, discharging the blade from the furnace after the temperature is reduced, and taking out the blade for cooling and cleaning when the temperature of powder and parts in the tool is lower than 50 ℃;

(7) And weighing the blade, blowing to clean sand, and preparing the aluminum-chromium co-permeation coating.

2. The process for producing an aluminum chromium co-diffusion coating for a gas turbine rotor blade according to claim 1, wherein: during dry sand blasting, the sand blasting pressure is 0.1-0.3Mpa, the sand blasting angle is 70-90 degrees, and the sand blasting distance is 200-300mm.

3. The process for producing an aluminum chromium co-diffusion coating for a gas turbine rotor blade according to claim 1, wherein: the particles of the corundum sand are more than or equal to 130 meshes.

4. The process for producing an aluminum chromium co-diffusion coating for a gas turbine rotor blade according to claim 1, wherein: and (3) introducing argon gas into the step (6) to cool the temperature, and discharging the furnace until the temperature in the furnace is lower than 200 ℃.

5. The process for producing an aluminum chromium co-diffusion coating for a gas turbine rotor blade according to claim 1, wherein: and (2) putting the aluminum oxide, the chromium powder and the aluminum powder into an oven, heating to 200-250 ℃ and preserving heat for 0.5-0.8 hour, putting the dried powder and the ammonium chloride into a mixer after the heat preservation is finished, stirring for 0.5-0.8 hour, and taking out.

6. The process for producing an aluminum chromium co-diffusion coating for a gas turbine rotor blade according to claim 1, wherein: the current of the alternating current electric field in the step (5) is 2A, and the voltage is 50-90V.