Method for reducing oxidation degree of bonding layer of thermal barrier coating in atmospheric plasma spraying process

Abstract

The invention provides a method for reducing the oxidation degree of a thermal barrier coating bonding layer in the atmosphere plasma spraying process. Comprising the following steps: step 1, aligning a sample (4) subjected to sand blasting to a plasma spray head (1); 2, opening a magnetic field generating device to generate a magnetic field; step 3, forming an inert gas shielding gas film (3) on the surface area of the sample (4); step 4, spraying is carried out; and 5, after the sample (4) is completely cooled, closing the gas-assisted protection device (2), and taking out the sample. Through an external magnetic field, plasma is accelerated and gathered, and the spraying speed of metal particles is increased; the phenomena of non-uniformity and scattering of a spraying agent caused by too high gas flow and speed in the spraying process are reduced, and a higher spraying speed can be applied, so that the spraying speed of metal particles is further increased; and the inert gas reduces the oxidation of the coating after spraying. Therefore, the oxidation degree of the bonding layer of the thermal barrier coating in the plasma spraying process is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of advanced manufacturing of aeroengines, and in particular to a method for reducing the oxidation degree of a bonding layer of a thermal barrier coating during atmospheric plasma spraying. Background Art

[0002] Thermal barrier coatings (TBCs) have been widely used in high-temperature components of advanced gas turbines and aircraft engines. TBCs can protect alloy components from high-temperature oxidation, corrosion and erosion to a certain extent, and extend the service life of the alloy. Atmospheric plasma spraying (APS) is the earliest technology used to prepare thermal barrier coatings. APS uses the plasma generated by arc discharge as a heat source to heat the coating powder to a molten or semi-molten state, and then atomizes it through a high-speed airflow, and is sprayed and deposited on the substrate surface at high speed. Compared with other spraying technologies, APS has a faster preparation speed, higher deposition efficiency, simpler operating procedures, and relatively low costs.

[0003] However, during the atmospheric plasma spraying process, the sprayed metal powder is in direct contact with the oxygen in the atmosphere, and is easily oxidized or decomposed at high temperatures, which will have an adverse effect on the coating thickness and strength of the coating. At present, researchers usually reduce the oxidation degree of metal powder by coating the powder, reducing the spraying temperature and increasing the particle spraying speed to reduce its oxidation temperature and time. However, the process of coating the powder is complicated and the cost is high. Lowering the spraying temperature will cause the powder to not melt fully. Accelerating the particle spraying speed will cause the spraying agent to be non-uniform and scatter, affecting the spraying quality. Therefore, there is an urgent need for a simple and low-cost method to reduce the oxidation of the bonding layer of the thermal barrier coating during atmospheric plasma spraying without adversely affecting the coating quality.

[0004] In order to reduce the oxidation of the bonding layer of the thermal barrier coating during the preparation of the thermal barrier coating, the present invention provides a method for reducing the oxidation of the bonding layer of the thermal barrier coating during atmospheric plasma spraying, so as to reduce the oxidation degree of the bonding layer of the thermal barrier coating during atmospheric plasma spraying. Summary of the invention

[0005] The object of the present invention is to provide a method for reducing the oxidation degree of the bonding layer of a thermal barrier coating during atmospheric plasma spraying.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention relates to a method for reducing the oxidation degree of a bonding layer of a thermal barrier coating during atmospheric plasma spraying, comprising the following steps:

[0008] Step 1, fix the sandblasted sample 4 on the sample holding platform 5, and align the sandblasted side with the plasma nozzle 1;

[0009] Step 2, turning on the magnetic field generating device, and generating a corresponding magnetic field in the area between the plasma nozzle 1 and the surface of the sample 4 by passing current into the magnetic induction coil 6;

[0010] Step 3, opening the gas auxiliary protection device 2, passing an inert gas to the surface of the sample 4, and forming an inert gas protection gas film 3 on the surface of the sample 4;

[0011] Step 4, turning on the plasma spray head 1, adjusting the plasma spraying parameters, spraying, and spraying the metal powder onto the surface of the sample 4;

[0012] Step 5, after spraying is completed, the plasma nozzle 1 and the magnetic field generating device are turned off, and the gas-assisted protection device 2 continues to introduce inert gas. After the sample 4 is completely cooled, the gas-assisted protection device 2 is turned off and the sample is taken out.

[0013] Preferably, in step 1, the sample 4 is one of a titanium alloy and a nickel-based high-temperature alloy, and has a thickness of 2 mm to 5 mm.

[0014] Preferably, in step 1, the sandblasting treatment is specifically: firstly degreasing the surface of the sample 4, and then roughening the surface of the sample 4 by sandblasting.

[0015] Preferably, the degreasing method is: removing oil stains on the surface of sample 4 with alcohol or acetone; the sandblasting method is: sandblasting the surface of sample 4 with Al2O3 with a particle size of 60 to 120 mesh to roughen the surface to a surface roughness of 1 to 20 μm.

[0016] Preferably, in step 2, the current passed through the magnetic induction coil 6 is a direct current with a current value of 0A to 10A, and the magnetic field generated in the magnetic induction coil 6 is a steady magnetic field with a magnetic field direction parallel to the flame flow direction of atmospheric plasma spraying.

[0017] Preferably, in step 3, the inert gas is one or a mixture of nitrogen, helium, neon and argon.

[0018] Preferably, in step 4, the sample 4 is preheated before spraying, and the preheating temperature is 200°C to 350°C.

[0019] Preferably, in step 4, the metal powder is one of MCrAlY and NiAl, or MCrAlY and (Ni, Pt)Al powders modified with Pt.

[0020] Preferably, in step 4, the plasma spraying parameters are: the distance between the plasma nozzle 1 and the sample 4 is 100-300 μm, the moving speed of the plasma nozzle 1 is 500-1000 mm / s, the powder feeding speed is 20-80 g / min, the gas feeding speed is 1.2-1.8 L / min, the H2 flow rate is 30-60 L / min, the Ar flow rate is 60-180 L / min, the spraying voltage is 120-200 V, and the current is 250-300 A.

[0021] Preferably, in step 5, the cooling temperature is lower than 200°C to 350°C.

[0022] The present invention has the following advantages:

[0023] The present invention introduces a steady magnetic field during the process of atmospheric plasma spraying of a thermal barrier coating bonding layer, accelerates and aggregates the plasma during the plasma spraying process, and the magnetic field accelerates the plasma so that the spraying speed of the metal particles is increased, thereby reducing the oxidation time thereof during the spraying process, and the magnetic field aggregates the plasma, thereby reducing the non-uniformity and scattering of the spraying agent caused by excessive gas flow and speed during the spraying process, and a larger gas flow and speed can be used to further increase the speed of metal particle spraying; the present invention reduces the oxidation of the coating after spraying by adding a gas auxiliary protection device, further reduces the oxidation of the bonding layer during the atmospheric plasma spraying bonding layer, and finally reduces the oxidation degree of the bonding layer of the thermal barrier coating during the atmospheric plasma spraying process, and has the characteristics of simple method and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the method involved in the present invention;

[0025] Figure 2 This is a comparison of the oxidation degree of the bonding layer before and after the introduction of a steady magnetic field;

[0026] The accompanying drawings are marked with: 1-plasma nozzle, 2-gas auxiliary protection device, 3-inert gas protection film, 4-sample, 5-sample clamping platform, 6-magnetic induction coil, 7-magnetic field generating device core, 8-insulating shell. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific embodiments. It should be noted that the following embodiments are only further descriptions of the present invention, but the protection scope of the present invention is not limited to the following embodiments.

[0028] Example 1

[0029] This embodiment relates to a method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying. Figure 1As shown, the steps are as follows:

[0030] In the first step, the surface of TC4 sample 4 was degreased with alcohol, and then the surface of sample 4 was roughened by sandblasting with Al2O3 with a particle size of 60 mesh;

[0031] The second step is to fix the TC4 sample 4 on the sample holding platform 5 and align the sandblasted side with the plasma nozzle 1;

[0032] The third step is to turn on the magnetic field generating device (including: magnetic induction coil 6, magnetic field generating device core 7, insulating shell 8); by passing 6A current into the magnetic induction coil 6, a corresponding magnetic field is generated around the sample 4;

[0033] The fourth step is to open the gas auxiliary protection device 2, pass the inert gas Ne to the surface of the sample 4, and form an inert gas protection gas film 3 on the surface of the sample 4;

[0034] In the fifth step, the sample 4 was preheated to 200°C, and then the NiAl bonding layer was sprayed using atmospheric plasma spraying parameters with the distance between the plasma nozzle 1 and the sample 4 being 150 μm, the moving speed of the plasma nozzle 1 being 600 mm / s, the powder feeding speed being 30 g / min, the gas feeding speed being 1.5 L / min, the H2 flow rate being 40 L / min, the Ar flow rate being 120 L / min, the spraying voltage being 150 V, and the current being 300 A;

[0035] Step 6: turn off the magnetic field generating device and the plasma nozzle 1, and when the sample 4 is cooled to below 200° C., turn off the gas auxiliary protection device 2 and take out the sample 4.

[0036] Example 2

[0037] This embodiment relates to a method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying. Figure 1 As shown, the steps are as follows:

[0038] In the first step, the surface of GH2907 sample 4 was degreased with acetone, and then the surface of sample 4 was roughened by sandblasting with Al2O3 with a particle size of 120 mesh;

[0039] The second step is to fix the GH2907 sample 4 on the sample holding platform 5 and align the sandblasted side with the plasma nozzle 1;

[0040] The third step is to turn on the magnetic field generating device (including: magnetic induction coil 6, magnetic field generating device core 7, insulating shell 8); by passing 6A current into the magnetic induction coil 6, a corresponding magnetic field is generated around the sample 4;

[0041] The fourth step is to open the gas auxiliary protection device 2, introduce inert gas Ar to the surface of the sample 4, and form an inert gas protection gas film 3 on the surface of the sample 4;

[0042] In the fifth step, the sample 4 is preheated to 300°C, and then the NiAl bonding layer is sprayed using atmospheric plasma spraying parameters with the distance between the plasma nozzle 1 and the sample 4 being 200 μm, the moving speed of the plasma nozzle 1 being 800 mm / s, the powder feeding speed being 20 g / min, the gas feeding speed being 1.2 L / min, the H2 flow rate being 30 L / min, the Ar flow rate being 120 L / min, the spraying voltage being 120 V, and the current being 250 A.

[0043] Step 6: turn off the magnetic field generating device and the plasma nozzle 1, and when the sample 4 is cooled to below 300° C., turn off the gas auxiliary protection device 2 and take out the sample 4.

[0044] The oxidation degree of the sample prepared in Example 1 of the present invention is compared with that of the sample without introducing a constant magnetic field. Figure 2 As shown (where (a) is before the introduction of a steady magnetic field; (b) is after the introduction of a steady magnetic field), from Figure 2 It can be seen that after the steady magnetic field is introduced into the present invention, the vein oxides in the bonding layer are significantly reduced and the oxidation degree of the bonding layer is significantly reduced. Figure 2 The comparison further proves that the present invention accelerates and aggregates the plasma through the external magnetic field, speeds up the spraying speed of metal particles, reduces the excessive gas flow and speed during the spraying process, causes the non-uniformity and scattering of the spraying agent, and can use a higher spraying speed, so that the speed of metal particle spraying is further increased; the inert gas reduces the oxidation of the coating after spraying. Therefore, the oxidation degree of the bonding layer of the thermal barrier coating during the plasma spraying process is effectively reduced.

[0045] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for reducing the degree of oxidation of a bonding layer of a thermal barrier coating during atmospheric plasma spraying, characterized in that: The following steps are involved: Step 1, fix the sandblasted sample (4) on the sample holding platform (5), and align the sandblasted side with the plasma nozzle (1); Step 2, turning on the magnetic field generating device, and generating a corresponding magnetic field in the area between the plasma nozzle (1) and the surface of the sample (4) by passing current into the magnetic induction coil (6); Step 3, opening the gas auxiliary protection device (2), passing an inert gas to the surface of the sample (4), and forming an inert gas protection gas film (3) on the surface area of ​​the sample (4); Step 4, turning on the plasma spray head (1), adjusting the plasma spraying parameters, and spraying to spray the metal powder onto the surface of the sample (4); Step 5, after the spraying is completed, the plasma nozzle (1) and the magnetic field generating device are turned off, and the gas auxiliary protection device (2) continues to introduce inert gas. After the sample (4) is completely cooled, the gas auxiliary protection device (2) is turned off and the sample is taken out.

2. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 1, the sample (4) is one of a titanium alloy and a nickel-based high-temperature alloy, and its thickness is 2 mm to 5 mm.

3. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 1, the sandblasting treatment specifically includes: firstly performing a degreasing treatment on the surface of the sample (4), and then performing a sandblasting roughening treatment on the surface of the sample (4).

4. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 3, characterized in that: The degreasing method is to remove the oil stains on the surface of the sample (4) with alcohol or acetone; the sandblasting method is to sandblast the surface of the sample (4) with Al2O3 having a particle size of 60 to 120 mesh until the surface roughness is 1 to 20 μm.

5. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 2, the current passed through the magnetic induction coil (6) is a direct current with a current value of 0A to 10A. The magnetic field generated in the magnetic induction coil (6) is a steady magnetic field with a magnetic field direction parallel to the flame flow direction of the atmospheric plasma spraying.

6. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 3, the inert gas is one or a mixture of nitrogen, helium, neon, and argon.

7. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 4, the sample (4) is preheated before spraying, and the preheating temperature is 200°C to 350°C.

8. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 4, the metal powder is one of MCrAlY and NiAl, or MCrAlY and (Ni, Pt)Al powders modified with Pt.

9. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 4, the plasma spraying parameters are as follows: the distance between the plasma nozzle (1) and the sample (4) is 100-300 μm, the moving speed of the plasma nozzle (1) is 500-1000 mm / s, the powder feeding speed is 20-80 g / min, the gas feeding speed is 1.2-1.8 L / min, the H2 flow rate is 30-60 L / min, the Ar flow rate is 60-180 L / min, the spraying voltage is 120-200 V, and the current is 250-300 A.

10. The method for reducing the degree of oxidation of the bonding layer of a thermal barrier coating during atmospheric plasma spraying according to claim 1, characterized in that: In step 5, the cooling temperature can be lower than 200°C to 350°C.

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