A method for preparing an aluminide coating having a pinning structure

Abstract

The present application relates to the technical field of coating preparation, and is a method for preparing an aluminide coating with a pinning structure, wherein a laser is used to preform defects on the surface of a high-temperature alloy sample using impact energy; the preformed defect sample is placed in a high-energy metal ion source injection device, the chamber of the device is evacuated, the coating surface is cleaned using a Kaufman ion source, and the parameters of the high-energy metal ion source injection device are adjusted to perform Y ion injection on the workpiece; the high-temperature alloy workpiece is subjected to aluminization by a powder embedding aluminization method, the workpiece is tightly wrapped with a mixed filler powder, placed in an alumina crucible, and the alumina crucible is sealed with refractory clay, and the alumina crucible is placed in a tubular furnace under argon protection, and is heated and insulated in sequence, and then cooled to room temperature. The present application improves the bonding strength of the membrane substrate by forming a pinning structure with a specific inclination angle, a thin top and a thick bottom, and enriches and injects active elements at the grain boundary, inhibits the diffusion of aluminum to the coating surface, and improves the high-temperature corrosion resistance life of the coating.

Description

Technical Field

[0001] The present application relates to the technical field of coating preparation, and in particular to a method for preparing an aluminide coating with a pinning structure. Background Art

[0002] When high-temperature alloys are in working condition, they are usually accompanied by high corrosion, high load, high-frequency vibration and other working conditions. Protective coatings are needed to improve the high-temperature corrosion resistance of high-temperature alloys. Aluminide coatings are currently widely used protective coatings. Under high-temperature conditions, there is a large difference in the thermal expansion coefficient of the film base, which is prone to cracking due to thermal mismatch, and the high-temperature corrosion resistance is seriously reduced. In addition, the aluminum element diffuses rapidly to the surface of the coating in a high-temperature environment. On the one hand, it causes the infiltrated aluminum to be consumed too quickly, causing the coating to fail, and the large amount of aluminum oxides generated will undergo phase changes with temperature, resulting in stress concentration in the coating, generating pores and cracks, and causing the coating to fail. Therefore, to improve the high-temperature corrosion resistance of aluminide coatings, on the one hand, it is necessary to improve the bonding strength of the film base, and on the other hand, it is necessary to regulate the film-base interface composition and reduce the aluminum diffusion rate. Summary of the invention

[0003] In order to overcome the problems existing in the prior art, the present application provides a method for preparing an aluminide coating with a pinning structure.

[0004] The present application provides a method for preparing an aluminide coating with a pinning structure using the following technical solution:

[0005] A preparation method of an aluminide coating with a pinning structure comprises the following steps: laser shock: using laser to preform defects on the surface of a high-temperature alloy sample using impact energy to form a preformed defect sample; ion implantation: placing the preformed defect sample in a high-energy metal ion source implantation device, evacuating the device chamber, cleaning the coating surface using a Kaufman ion source, and implanting Y ions into the workpiece after adjusting the parameters of the high-energy metal ion source implantation device; powder embedding: using a powder embedding aluminizing method to perform an aluminizing process on the high-temperature alloy workpiece after ion implantation, firstly mixing filler powders, tightly wrapping the treated high-temperature alloy workpiece with the mixed filler powders, placing it in an alumina crucible, sealing the alumina crucible with refractory clay, and then placing the alumina crucible in a tubular furnace under argon protection, heating and keeping the temperature in turn, and then cooling to room temperature.

[0006] Preferably, the laser beam in the laser shock forms an angle of 5-20° with the surface normal of the high-temperature alloy sample, the laser energy is 8-10 kW, the laser pulse frequency is 1000 Hz-2000 Hz, and the laser movement rate is 200-1000 mm / min.

[0007] Preferably, the pressure in the high energy metal ion source injection device needs to be pumped to 1×10-5 Below Pa.

[0008] Preferably, the coating surface cleaning time during ion implantation is 20-30 minutes.

[0009] Preferably, the arc voltage is adjusted to 45V-55V in the high-energy metal ion source injection equipment, the trigger frequency is adjusted to 6Hz-10Hz, and the arc current is 0.4A-0.6A; the extraction voltage is increased to 45kV, the suppression voltage is increased to above 1kV, and the suppression current is adjusted to within 3mA; after the above parameters are stabilized, the extraction voltage is increased to 70kV-100kV.

[0010] Preferably, the injection time of Y ions is 180 min-240 min.

[0011] Preferably, the filler powder components in the powder embedding are Al2O3, Cr, Al, Y2O3, CeO2, HfO2 and NH4Cl, wherein the Al powder content is 30-40wt.%, and the Al2O3 powder content is 40-50wt.%.

[0012] Preferably, when the alumina crucible is placed in a tube furnace during powder embedding, the temperature in the furnace is increased to 900°C at a rate of 10°C / min, and maintained at this temperature for 6h-10h, and then cooled to room temperature. The sample is always protected by argon during the whole process.

[0013] In summary, the present application includes at least one of the following beneficial technical effects:

[0014] The present application uses a variety of means to regulate the membrane-substrate interdiffusion interface, and forms a pinning structure similar to mortise and tenon joints through oblique defects to improve the bonding strength of the membrane-substrate;

[0015] The present application enriches and injects active elements at the grain boundaries to inhibit the diffusion of aluminum to the coating surface, thereby greatly improving the high temperature corrosion resistance life of the coating;

[0016] This application adopts three mature and simple processes: laser shock, ion implantation and powder embedding infiltration. Therefore, this scheme has the technical advantage of strong operability and is conducive to promotion to industrial production.

[0017] The process of the present application generates no pollutants or waste gas, does not cause harm to the environment, and has the advantages of being green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the laser shock prefabricated defect;

[0019] Figure 2 It is a pinning structure of powder-embedded aluminide;

[0020] Figure 3 It is a pinning structure of powder-embedded aluminide;

[0021] Figure 4 The surface morphologies of the coatings corroded in NaCl and NaSO4 molten salts at 1100°C for (a) 3h, (b) 10h, (c) 15h, and (d) 20h, respectively.

[0022] Description of the drawings: 1. Laser; 2. Prefabricated defects; 3. High-temperature alloy. DETAILED DESCRIPTION

[0023] The following is combined with Figure 1-4 This application is described in further detail.

[0024] The embodiment of the present application discloses a method for preparing an aluminide coating with a pinning structure.

[0025] Example 1: Reference Figure 1 , a method for preparing an aluminide coating having a pinning structure, comprising the following steps:

[0026] Laser 1 impact: Laser 1 is used to utilize impact energy to preform defect 2 on the surface of high-temperature alloy 3 sample to form preformed defect 2 sample. The laser 1 beam in laser 1 impact forms an angle of 20° with the surface normal of the high-temperature alloy 3 sample. The laser 1 energy is 10 kW, the laser 1 pulse frequency is 2000 Hz, and the laser 1 moving rate is 1000 mm / min.

[0027] Ion implantation: Place the prefabricated defect 2 sample in a high-energy metal ion source implantation device, and pump the pressure in the high-energy metal ion source implantation device to 0.8×10 -5 Pa, use the Kaufman ion source to clean the coating surface for 30 minutes, adjust the arc voltage to 55V, adjust the trigger frequency to 10Hz, and the arc current to 0.6A; increase the extraction voltage to 45kV, the suppression voltage to 2kV, and adjust the suppression current to 2.5mA; after the above parameters are stable, increase the extraction voltage to 100kV, and then perform Y ion implantation on the workpiece for 240 minutes;

[0028] Powder embedding: The high-temperature alloy 3 workpiece after ion implantation was subjected to aluminization process by powder embedding aluminization method. First, filler powders with components of Al2O3, Cr, Al, Y2O3, CeO2, HfO2 and NH4Cl, wherein the Al powder content was 40wt.%, and the Al2O3 powder content was 50wt.%, were mixed. The treated high-temperature alloy 3 workpiece was tightly wrapped with the mixed filler powder and placed in an alumina crucible. The alumina crucible was sealed with refractory clay. Then, under the protection of argon, the alumina crucible was loaded into a tube furnace, and the furnace temperature was increased to 900℃ at a rate of 10℃ / min, and maintained at this temperature for 10h, and then cooled to room temperature. The sample was always protected by argon during the whole process.

[0029] Example 2: Reference Figure 1 , a method for preparing an aluminide coating having a pinning structure, comprising the following steps:

[0030] Laser 1 impact: Laser 1 is used to utilize impact energy to preform defect 2 on the surface of high-temperature alloy 3 sample to form preformed defect 2 sample. The laser 1 beam in laser 1 impact forms an angle of 5° with the surface normal of the high-temperature alloy 3 sample. The laser 1 energy is 8 kW, the laser 1 pulse frequency is 1000 Hz, and the laser 1 moving rate is 200 mm / min.

[0031] Ion implantation: Place the prefabricated defect 2 sample in a high-energy metal ion source implantation device, and pump the pressure in the high-energy metal ion source implantation device to 0.6×10 -5 Pa, use the Kaufman ion source to clean the coating surface for 20 minutes, adjust the arc voltage to 45V, adjust the trigger frequency to 6HzHz, and the arc current to 0.4A; increase the extraction voltage to 45kV, the suppression voltage to 3kV, and adjust the suppression current to 2mA; after the above parameters are stable, increase the extraction voltage to 70kV, and then perform Y ion implantation on the workpiece for 180 minutes;

[0032] Powder embedding: The high-temperature alloy 3 workpiece after ion implantation was subjected to aluminization process by powder embedding aluminization method. First, filler powders with components of Al2O3, Cr, Al, Y2O3, CeO2, HfO2 and NH4Cl, wherein the Al powder content was 30wt.%, and the Al2O3 powder content was 40wt.%, were mixed. The treated high-temperature alloy 3 workpiece was tightly wrapped with the mixed filler powder and placed in an alumina crucible. The alumina crucible was sealed with refractory clay. Then, under the protection of argon, the alumina crucible was loaded into a tube furnace, and the furnace temperature was increased to 900℃ at a rate of 10℃ / min, and maintained at this temperature for 6h, and then cooled to room temperature. The sample was always protected by argon during the whole process.

[0033] By prefabricating defects with a certain angle on the surface of the high-temperature alloy 3, the aluminide coating can diffuse along the oblique defects during the infiltration process, such as Figure 2 and Figure 3 As shown in the figure, the interdiffusion interface between aluminide and high-temperature alloy 3 matrix produces a pinning structure, and the bonding strength of the coating is greatly improved. At the same time, by injecting Y ions, it is enriched at the oxide grain boundary, blocking the diffusion path of aluminum, slowing down the rate of aluminum diffusion from the interdiffusion layer to the sample surface under high temperature environment, making the Al2O3 content in the coating increase slowly, reducing the stress of the coating caused by Al2O3 phase transformation, and inhibiting the generation of cracks and pores in the coating. Figure 4 As shown in the figure, the surface morphology of the corrosion in NaCl and NaSO4 molten salts at 1100℃, after 3h, 10h, 15h and 20h of hot corrosion respectively, no cracks were generated in the surface coating.

[0034] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an aluminide coating having a pinning structure, characterized in that: The following steps are involved: Laser (1) impact: using laser (1) to use impact energy to preform defects (2) on the surface of a high-temperature alloy (3) sample to form preformed defects (2) sample; Ion implantation: Place the prefabricated defect (2) sample in a high-energy metal ion source implantation device, evacuate the device chamber, use a Kaufman ion source to clean the coating surface, adjust the parameters of the high-energy metal ion source implantation device, and then implant Y ions into the workpiece; Powder embedding: The high-temperature alloy (3) workpiece after ion implantation is subjected to aluminizing process by powder embedding aluminizing method. First, the filler powder is mixed, and the treated high-temperature alloy (3) workpiece is tightly wrapped with the mixed filler powder, and then placed in an alumina crucible, and the alumina crucible is sealed with refractory clay. Then, under the protection of argon gas, the alumina crucible is placed in a tube furnace, and the temperature is raised, kept warm, and then cooled to room temperature in sequence; The filler powder components in the powder embedding are Al2O3, Cr, Al, Y2O3, CeO2, HfO2 and NH4Cl, wherein the Al powder content is 30-40wt.%, and the Al2O3 powder content is 40-50wt.%.

2. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: The laser (1) beam in the laser (1) impact forms an angle of 5-20° with the surface normal of the high-temperature alloy (3) sample, the laser (1) energy is 8-10 kW, the laser (1) pulse frequency is 1000 Hz-2000 Hz, and the laser (1) moving speed is 200-1000 mm / min.

3. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: The pressure in the high energy metal ion source injection device needs to be pumped to 1×10 -5 Below Pa.

4. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: The coating surface cleaning time during the ion implantation is 20-30 minutes.

5. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: In the high-energy metal ion source injection equipment, the arc voltage is adjusted to 45V-55V, the trigger frequency is adjusted to 6Hz-10Hz, and the arc current is adjusted to 0.4A-0.6A; the extraction voltage is increased to 45kV, the suppression voltage is increased to more than 1kV, and the suppression current is adjusted to within 3mA; after the above parameters are stable, the extraction voltage is increased to 70kV-100kV.

6. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: The injection time of the Y ions is 180 min-240 min.

7. The method for preparing an aluminide coating having a pinning structure according to claim 1, characterized in that: When the alumina crucible is placed in a tube furnace during the powder embedding process, the temperature in the furnace is increased to 900°C at a rate of 10°C / min, and maintained at this temperature for 6h-10h, and then cooled to room temperature. During the whole process, the sample is always protected by argon.

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