阅读说明：本技术 一种涡轮叶片上铬改性铝化物涂层的制备方法 (Preparation method of chromium modified aluminide coating on turbine blade ) 是由 李阳 张华� 李淑文 王文军 王军 廉铁江 佟飞 张勇 于 2020-11-30 设计创作，主要内容包括：本发明提供一种涡轮叶片上铬改性铝化物涂层的制备方法,包括：S1,将渗剂和涡轮叶片置于工装上；S2,将工装吊入气渗金属炉中,气渗金属炉预抽真空；S3,将气渗金属炉升温至1000～1050℃,保温3～5小时,随炉冷却至800℃以下后将工装吊出空冷；S4,将涡轮叶片进行清洗,并晾干。本发明制备方法采用的设备较为成熟,使用固体渗剂,不需外部通入反应气体,现阶段本发明工艺方法的可行性较强,可在涡轮叶片铬改性铝化物涂层制备方面进行全方面推广与应用。(The invention provides a preparation method of a chromium modified aluminide coating on a turbine blade, which comprises the following steps: s1, placing an infiltration agent and the turbine blade on a tool; s2, hoisting the tool into a gas-metal infiltration furnace, and vacuumizing the gas-metal infiltration furnace in advance; s3, heating the gas-diffusion metal furnace to 1000-1050 ℃, preserving heat for 3-5 hours, cooling the furnace to below 800 ℃, and then taking out the tool for air cooling; and S4, cleaning the turbine blade and airing. The preparation method provided by the invention adopts mature equipment, uses a solid penetrating agent, does not need to introduce reaction gas outside, has strong feasibility at the present stage, and can be comprehensively popularized and applied in the preparation aspect of the turbine blade chromium modified aluminide coating.)

1. A preparation method of a chromium modified aluminide coating on a turbine blade is characterized by comprising the following steps:

s1, placing an infiltration agent and the turbine blade on a tool;

s2, hoisting the tool into a gas-metal infiltration furnace, and vacuumizing the gas-metal infiltration furnace in advance;

s3, heating the gas-diffusion metal furnace to 1000-1050 ℃, preserving heat for 3-5 hours, cooling the furnace to below 800 ℃, and then taking out the tool for air cooling;

and S4, cleaning the turbine blade and airing.

2. The method for preparing the chromium-modified aluminide coating on the turbine blade as recited in claim 1, wherein in S2, a muffle tank is arranged in the gas-permeable metal furnace, the tool is hung in the muffle tank, and the pressure in the muffle tank is pumped to be less than or equal to 30 Pa.

3. The method for preparing the chromium-modified aluminide coating on the turbine blade as recited in claim 2, wherein in S3, a fan equipped in a muffle tank is in a working state during heat preservation.

4. The method of making a chromium-modified aluminide coating on a turbine blade as recited in claim 3, wherein the fan is a centrifugal fan.

5. The method of claim 1, wherein in S1, the infiltrant is selected from the group consisting of powdered iron-aluminum, powdered chromium, and powdered ammonium chloride.

6. The method for preparing the chromium modified aluminide coating on the turbine blade as claimed in claim 5, wherein the weight of the iron-aluminum powder is 50-70% of the total weight of the penetrating agent, the weight of the ammonium chloride powder is 1-5% of the total weight of the penetrating agent, and the balance is chromium powder.

7. The method of preparing a chromium-modified aluminide coating on a turbine blade as recited in claim 1, wherein in S1, the infiltrant is formulated as: and (3) ball-milling and mixing the iron-aluminum powder, the chromium powder and the ammonium chloride powder to obtain the penetrant.

8. The method of claim 1, wherein in step S1, the turbine blade is subjected to sand blasting and then placed on a tool.

9. The method of claim 8, wherein the blasting is performed with Al₂O₃And molding sand, wherein the granularity range of the sand is 120-220 meshes, and the air pressure range of sand blowing is 0.1-0.3 MPa.

10. The method for preparing the chromium-modified aluminide coating on the turbine blade as recited in claim 1, wherein in S4, the turbine blade is cleaned by being placed in an ultrasonic cleaning tank.

Technical Field

The invention belongs to the technical field of metal heat treatment, and relates to a preparation method of a chromium modified aluminide coating on a turbine blade, which is used for preparing the chromium modified aluminide coating on the surface of a turbine blade runner and a complex inner cavity.

Background

High-temperature oxidation and high-temperature corrosion are common failure modes of aeroengine turbine blades, and once the oxidation and corrosion phenomena occur, a matrix material is directly damaged, so that the mechanical property is sharply reduced. With the inlet temperature of the turbine of the engine being higher and higher, the service condition of the blade is worse and worse, and the protection requirement on the surface and the complex inner cavity of the turbine blade is higher and higher. The aluminide infiltration layer has better high-temperature corrosion resistance, and is one of the most common protection methods for the turbine blade.

In recent years, Cr element modified aluminide diffusion layers are more and more widely applied because the Ni-Al phase diffusion layers of single aluminide diffusion layers have higher brittleness and are easy to crack and strip, Al diffuses to a matrix quickly during high-temperature service, and the surface aluminum content is reduced to lose the protection effect. The modified coating can effectively reduce the degradation rate of the coating, slow down the generation of a martensite transformation process in a nickel-rich beta-NiAl phase, and improve the phase structure stability and the hot corrosion resistance of the coating.

At present, the preparation process of the Cr-Al coating basically focuses on embedding co-permeation, physical vapor deposition, electrodeposition and a Chemical Vapor Deposition (CVD) method, wherein the embedding co-permeation, the physical vapor deposition and the electrodeposition can not realize the preparation of a permeation layer of a complex inner cavity of a turbine blade, the existing chemical vapor deposition method can realize the accurate control of the atmosphere in a furnace by introducing various reaction gases into a tank body, but the related equipment has high value and is difficult to popularize at the present stage.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a preparation method of a chromium modified aluminide coating on a turbine blade, which can realize the preparation of the chromium modified aluminide coating on the surface and a complex inner cavity of the turbine blade and has stronger feasibility.

The invention is realized by the following technical scheme:

a preparation method of a chromium modified aluminide coating on a turbine blade comprises the following steps:

s1, placing an infiltration agent and the turbine blade on a tool;

s2, hoisting the tool into a gas-metal infiltration furnace, and vacuumizing the gas-metal infiltration furnace in advance;

s3, heating the gas-diffusion metal furnace to 1000-1050 ℃, preserving heat for 3-5 hours, cooling the furnace to below 800 ℃, and then taking out the tool for air cooling;

and S4, cleaning the turbine blade and airing.

Preferably, in S2, a muffle tank is provided in the gas-metal infiltration furnace, the tool is suspended in the muffle tank, and the pressure in the muffle tank is pumped to 30Pa or less.

Further, in the S3, the fan arranged in the muffle tank is in a working state in the heat preservation process.

Still further, the fan is a centrifugal fan.

Preferably, in S1, the impregnation agent is composed of powdered iron-aluminum, powdered chromium, and powdered ammonium chloride.

Further, the weight of the iron-aluminum powder is 50-70% of the total weight of the penetrating agent, the weight of the ammonium chloride powder is 1-5% of the total weight of the penetrating agent, and the balance is chromium powder.

Preferably, in S1, the penetrant is formulated as: and (3) ball-milling and mixing the iron-aluminum powder, the chromium powder and the ammonium chloride powder to obtain the penetrant.

Preferably, in S1, the turbine blade is first subjected to a sand blasting process and then placed on a tool.

Further, the sand blowing adopts Al₂O₃And molding sand, wherein the granularity range of the sand is 120-220 meshes, and the air pressure range of sand blowing is 0.1-0.3 MPa.

Preferably, in S4, the turbine blade is cleaned by being placed in an ultrasonic cleaning tank.

Compared with the prior art, the invention has the following beneficial technical effects:

the novel preparation method of the chromium modified aluminide coating has the advantages that the penetrating agent is not in direct contact with a workpiece, and the appearance quality of the part is good. Compared with the existing methods such as embedding co-infiltration, physical vapor deposition and electrodeposition, the method provided by the invention can be used for preparing the chromium modified aluminide coating of the complex inner cavity of the turbine blade; compared with the existing chemical vapor deposition method, the method has the advantages that the adopted equipment is mature, the solid penetrating agent is used, reaction gas does not need to be introduced from the outside, the feasibility of the process method is high at the present stage, and the method can be comprehensively popularized and applied in the preparation aspect of the chromium modified aluminide coating of the turbine blade. The infiltration layer prepared by the method has uniform tissue and controllable depth, and can obviously improve the high-temperature corrosion resistance of the blade.

Further, the fan is used for circulating the atmosphere in the muffle tank, and active aluminum and chromium atoms are supplemented into the inner cavity of the turbine blade.

Drawings

FIG. 1 is a process flow of the present invention;

FIG. 2 is an electron micrograph of a coating obtained in example 4 of the present invention;

FIG. 3 is a microstructure of group A samples after high temperature oxidation in accordance with the present invention.

FIG. 4 is a microstructure of group B samples after high temperature oxidation in accordance with the present invention.

FIG. 5 shows the microstructure of group A samples after high temperature etching in accordance with the present invention.

FIG. 6 is a microstructure of group B samples after high temperature etching in accordance with the present invention.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

Referring to fig. 1, the preparation steps of the turbine blade complex inner cavity chromium modified aluminide coating provided by the invention are as follows:

(1) preparing a penetrating agent: the penetrant consists of iron-aluminum powder, chromium powder and ammonium chloride powder, wherein the weight of the iron-aluminum powder accounts for 50-70% of the total weight, the weight of the ammonium chloride accounts for 1-5% of the total weight, and the balance is the chromium powder.

(2) Stirring: the prepared penetrating agent needs to be ball-milled on a rolling rod type ball mill for more than or equal to 1 hour, so that all the components are fully and uniformly stirred.

(3) Blowing sand: the turbine blade is subjected to sand blowing treatment, and the sand blowing adopts Al₂O₃Moulding sand, sandThe granularity range of the sand blasting is 120-220 meshes, and the air pressure range of the sand blasting is 0.1-0.3 MPa.

(4) Charging: spreading a permeating agent in a tool tray, putting the turbine blade cleaned by sand blowing into a tool clamping groove, then hoisting the tool into a muffle tank positioned in a high-temperature furnace, and vacuumizing the high-temperature furnace in advance.

(5) Vacuumizing: and pumping the pressure in the muffle tank to be less than or equal to 30Pa by using a mechanical pump.

(6) Heating, heat preservation and cooling: and (3) heating the muffle tank to 1000-1050 ℃ along with the furnace, opening a centrifugal stirring fan arranged in the muffle tank, preserving heat for 3-5 hours, cooling to below 800 ℃ along with the furnace, and then lifting the tool out for air cooling.

(7) Cleaning: and (3) putting the turbine blade into an ultrasonic cleaning tank for cleaning, removing the aluminized reactant on the surface, and airing.

(8) Metallographic or scanning electron microscopy SEM analysis: and carrying out metallographic or scanning electron microscope SEM analysis on the turbine blade, and detecting the depth and the structure of a permeable layer.

Example 1

(1) Preparing a penetrating agent: the penetrant consists of iron-aluminum powder, chromium powder and ammonium chloride powder, wherein the weight of the iron-aluminum powder accounts for 60 percent of the total weight, the weight of the ammonium chloride accounts for 2 percent of the total weight, and the balance is the chromium powder.

(2) Stirring: the prepared penetrating agent needs to be ball-milled on a rolling rod type ball mill for 3 hours, so that all the components are fully and uniformly stirred.

(3) Blowing sand: the turbine blade is subjected to sand blowing treatment, and the sand blowing adopts Al₂O₃And molding sand, wherein the granularity range of the sand is 220 meshes, and the air pressure range of sand blowing is 0.2 MPa.

(4) Charging: spreading a permeating agent in a tool tray, putting the turbine blade cleaned by sand blowing into a tool clamping groove, then hoisting the tool into a muffle tank positioned in a high-temperature furnace, and vacuumizing the high-temperature furnace in advance.

(5) Vacuumizing: the pressure in the muffle tank was pumped to 10Pa by a mechanical pump.

(6) Heating, heat preservation and cooling: and (3) heating the muffle tank to 1000 ℃ along with the furnace, opening a centrifugal stirring fan arranged in the muffle tank, preserving heat for 5 hours, cooling to 800 ℃ along with the furnace, and then lifting the tool out for air cooling.

(7) Cleaning: and (3) putting the turbine blade into an ultrasonic cleaning tank for cleaning, removing the aluminized reactant on the surface, and airing.

(8) Metallographic or scanning electron microscopy SEM analysis: and carrying out metallographic or scanning electron microscope SEM analysis on the turbine blade, and detecting the depth and the structure of a permeable layer.

Example 2

(1) Preparing a penetrating agent: the penetrant consists of iron-aluminum powder, chromium powder and ammonium chloride powder, wherein the weight of the iron-aluminum powder accounts for 60 percent of the total weight, the weight of the ammonium chloride accounts for 2 percent of the total weight, and the balance is the chromium powder.

(2) Stirring: the prepared penetrating agent needs to be ball-milled on a rolling rod type ball mill for 1 hour, so that all the components are fully and uniformly stirred.

(3) Blowing sand: the turbine blade is subjected to sand blowing treatment, and the sand blowing adopts Al₂O₃And molding sand, wherein the granularity range of the sand is 120 meshes, and the air pressure range of sand blowing is 0.1 MPa.

(4) Charging: spreading a permeating agent in a tool tray, putting the turbine blade cleaned by sand blowing into a tool clamping groove, then hoisting the tool into a muffle tank positioned in a high-temperature furnace, and vacuumizing the high-temperature furnace in advance.

(5) Vacuumizing: the pressure in the muffle tank was pumped to 15Pa by a mechanical pump.

(6) Heating, heat preservation and cooling: and (3) heating the muffle tank to 1015 ℃ along with the furnace, opening a centrifugal stirring fan arranged in the muffle tank, preserving heat for 4 hours, cooling to 800 ℃ along with the furnace, and then lifting the tool out for air cooling.

(7) Cleaning: and (3) putting the turbine blade into an ultrasonic cleaning tank for cleaning, removing the aluminized reactant on the surface, and airing.

(8) Metallographic or scanning electron microscopy SEM analysis: and carrying out metallographic or scanning electron microscope SEM analysis on the turbine blade, and detecting the depth and the structure of a permeable layer.

Example 3

(1) Preparing a penetrating agent: the penetrant consists of iron-aluminum powder, chromium powder and ammonium chloride powder, wherein the weight of the iron-aluminum powder accounts for 50% of the total weight, the weight of the ammonium chloride accounts for 1% of the total weight, and the balance is the chromium powder.

(2) Stirring: the prepared penetrating agent needs to be ball-milled on a rolling rod type ball mill for more than or equal to 1 hour, so that all the components are fully and uniformly stirred.

(3) Blowing sand: the turbine blade is subjected to sand blowing treatment, and the sand blowing adopts Al₂O₃And molding sand, wherein the granularity range of the sand is 150 meshes, and the air pressure range of sand blowing is 0.3 MPa.

(4) Charging: spreading a permeating agent in a tool tray, putting the turbine blade cleaned by sand blowing into a tool clamping groove, then hoisting the tool into a muffle tank positioned in a high-temperature furnace, and vacuumizing the high-temperature furnace in advance.

(5) Vacuumizing: the pressure in the muffle tank was pumped to 20Pa by a mechanical pump.

(6) Heating, heat preservation and cooling: and (3) heating the muffle tank to 1035 ℃ along with the furnace, opening a centrifugal stirring fan arranged in the muffle tank, preserving the heat for 3.5 hours, cooling the muffle tank to 800 ℃ along with the furnace, and then taking the tool out for air cooling.

(7) Cleaning: and (3) putting the turbine blade into an ultrasonic cleaning tank for cleaning, removing the aluminized reactant on the surface, and airing.

(8) Metallographic or scanning electron microscopy SEM analysis: and carrying out metallographic or scanning electron microscope SEM analysis on the turbine blade, and detecting the depth and the structure of a permeable layer.

Example 4

(1) Preparing a penetrating agent: the penetrant consists of iron-aluminum powder, chromium powder and ammonium chloride powder, wherein the weight of the iron-aluminum powder accounts for 70 percent of the total weight, the weight of the ammonium chloride accounts for 5 percent of the total weight, and the balance is the chromium powder.

(2) Stirring: the prepared penetrating agent needs to be ball-milled on a rolling rod type ball mill for 3 hours, so that all the components are fully and uniformly stirred.

(3) Blowing sand: the turbine blade is subjected to sand blowing treatment, and the sand blowing adopts Al₂O₃And molding sand, wherein the granularity range of the sand is 220 meshes, and the air pressure range of sand blowing is 0.2 MPa.

(4) Charging: spreading a permeating agent in a tool tray, putting the turbine blade cleaned by sand blowing into a tool clamping groove, then hoisting the tool into a muffle tank positioned in a high-temperature furnace, and vacuumizing the high-temperature furnace in advance.

(5) Vacuumizing: the pressure in the muffle tank was pumped to 30Pa by a mechanical pump.

(6) Heating, heat preservation and cooling: and (3) heating the muffle tank to 1050 ℃ along with the furnace, opening a centrifugal stirring fan arranged in the muffle tank, preserving heat for 3 hours, cooling to 800 ℃ along with the furnace, and then lifting the tool out for air cooling.

(7) Cleaning: and (3) putting the turbine blade into an ultrasonic cleaning tank for cleaning, removing the aluminized reactant on the surface, and airing.

(8) Metallographic or scanning electron microscopy SEM analysis: and carrying out metallographic or scanning electron microscope SEM analysis on the turbine blade, and detecting the depth and the structure of a permeable layer.

The micro-morphology of the chromium-modified aluminide coating obtained in example 4 is shown in fig. 2, the depth of the aluminum chromizing layer is 20-50 μm, the structure is uniform, and a typical two-layer structure is shown, namely: the outer layer is a seepage zone and the inner layer is a diffusion zone.

In order to verify the influence of the prepared chromium modified aluminide coating on the high-temperature oxidation resistance and the high-temperature corrosion resistance of the turbine blade, a high-temperature oxidation test and a salt-coating high-temperature corrosion test of samples in two states are designed, and the microscopic morphology of the samples is observed by adopting a metallographic method or a scanning electron microscope.

Group A: a blank sample of K465 material;

group B: a K465 sample of the chromium-modified aluminide coating prepared in example 4 of the present invention;

a. high temperature oxidation test

Test parameters are as follows: 1100 +/-10 ℃ for 200 hours.

The microstructure of the group a samples is shown in fig. 3.

The microstructure of the group B samples is shown in fig. 4.

And (3) morphology analysis: the microstructure of the group A sample can see more serious oxidation and falling under 350 multiplied by the number; the microstructure of group B samples still showed relatively complete bleeding at 1600X. The prepared chromium modified aluminide coating can effectively improve the high-temperature oxidation resistance of a matrix (K465).

b. Salt-coated high temperature corrosion test

Coating a salt component: 5% NaCl + 95% Na₂SO₄(wt％)

Test parameters are as follows: 950 +/-10 ℃ for 100 hours

The microstructure of the group a samples is shown in fig. 5.

The microstructure of the group B samples is shown in fig. 6.

And (3) morphology analysis: the microstructure of the group A sample is obviously corroded and consumed when observed under the condition of 100 multiplied by 100; the B group of samples have complete surfaces after salt-coating high-temperature corrosion tests, and the corrosion degree of a matrix can be obviously light under the condition of 100 multiplied by the X number. The prepared chromium modified aluminide coating can effectively improve the high-temperature corrosion resistance of a matrix (K465).

In conclusion, the preparation method can realize the preparation of the chromium modified aluminide coating on the surface of the turbine blade runner and the complex inner cavity, the prepared coating has uniform tissue and controllable depth, and the high-temperature oxidation resistance and the high-temperature corrosion resistance of the blade can be obviously improved.