High-temperature anti-oxidation coating as well as preparation method and preparation device thereof

Abstract

The invention provides a preparation method of an anti-oxidation coating from inside to outside, which comprises the following steps: A) preparing an MCrAlY alloy layer on the surface of a pretreated matrix, M being one or more selected from Ni, Co or Fe; b) spraying MCrAlY powder and nano ceramic powder on the surface of the MCrAlY alloy layer to obtain a nanocrystalline composite layer; c, the nanocrystalline composite layer is subjected to laser remelting and then cooled, and the anti-oxidation coating is obtained.The compact diffusion barrier layer is prepared through a controllable atmosphere spraying technology, is used for inhibiting easy-to-oxidize elements in a base body from migrating to the surface under the high-temperature service condition and is suitable for high-temperature components such as aero-engine blades and nuclear reactor components.

Description

Technical Field

[0001] This invention belongs to the field of high-temperature protective coating technology, specifically relating to a high-temperature antioxidant coating, its preparation method, and preparation apparatus. Background Technology

[0002] In the field of high-temperature anti-oxidation coatings, traditional technologies (such as MCrAlY coatings) can form surface oxide films, but during long-term service, easily oxidized elements such as Cr and Ti inside the substrate continue to diffuse to the surface, leading to the formation of Kirkendall voids, substrate depletion zones, and internal oxidation failure at the coating / substrate interface. Existing improvement solutions, such as multi-layer spraying, are prone to peeling due to interlayer thermal stress, and adding rare earth elements only improves density but cannot block element diffusion. Although the spraying process developed by Russia has proven that diffusion can be suppressed through nanocrystalline structures, there is a lack of dedicated equipment to achieve the industrial-scale preparation of dense coatings with a thickness of about 100 micrometers and a porosity of <2%.

[0003] Therefore, providing a high-density high-temperature protective coating that inhibits the migration of easily oxidized elements from the substrate to the surface under high-temperature service conditions has become a problem that needs to be solved. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a high-temperature anti-oxidation coating and its preparation method. The high-temperature anti-oxidation coating provided by the present invention can inhibit the migration of easily oxidized elements inside the substrate to the surface under high-temperature service conditions, and is suitable for high-temperature components such as aero-engine blades and nuclear reactor components.

[0005] This invention provides a method for preparing a high-temperature antioxidant coating, comprising the following steps:

[0006] A) Prepare an MCrAlY alloy layer on a pretreated substrate surface, wherein M is selected from one or more of Ni, Co, or Fe;

[0007] B) Spraying MCrAlY powder and nano-ceramic powder onto the surface of the MCrAlY alloy layer to obtain a nanocrystalline composite layer;

[0008] C) The nanocrystalline composite layer is laser remelted and then post-processed to obtain a high-temperature anti-oxidation coating.

[0009] Preferably, in step A), a metal alloy powder is sprayed using a supersonic flame to prepare an MCrAlY alloy layer on the pretreated substrate surface.

[0010] Preferably, the flame temperature of the supersonic flame spraying is 2600-3000℃, and the powder feeding rate is 30-70g / min;

[0011] The metal alloy powder is an MCrAlY type alloy, and the particle size of the metal alloy powder is 10-53 μm.

[0012] Preferably, the thickness of the MCrAlY alloy layer is 40~80μm.

[0013] Preferably, the nano-ceramic powder is selected from one or more of rare earth oxide-stabilized zirconium oxide, alumina, and spinel-type oxides, and is preferably Y2O3-ZrO2 powder;

[0014] The particle size of the nano-ceramic powder is 20~200nm.

[0015] Preferably, the volume percentage of the nano-ceramic powder to the total volume of MCrAlY powder and nano-ceramic powder is 15% to 40%.

[0016] Preferably, the power of the laser beam used for laser remelting is 2~2.8kW.

[0017] Preferably, after laser remelting, non-porous nano-equiaxed crystals are formed within a depth of 5~20μm on the surface of the coating.

[0018] Preferably, the post-processing is aerosol cooling, and the aerosol cooling temperature is below 200°C.

[0019] The present invention also provides a high-temperature antioxidant coating prepared by the above preparation method, wherein the high-temperature antioxidant coating has a thickness of 80~120μm and a porosity of <2%.

[0020] The present invention also provides a high-temperature antioxidant coating preparation system, comprising: a sealed spraying chamber, a high-speed flame spraying system, a powder supply module, an in-situ laser irradiation module, and a substrate preheating / cooling system.

[0021] Compared with existing technologies, this invention provides a method for preparing an anti-oxidation coating from the inside out, comprising the following steps: A) preparing an MCrAlY alloy layer on a pretreated substrate surface, where M is selected from one or more of Ni, Co, or Fe; B) spraying MCrAlY powder and nano-ceramic powder onto the surface of the MCrAlY alloy layer to obtain a nanocrystalline composite layer; C) laser remelting and cooling the nanocrystalline composite layer to obtain an anti-oxidation coating. This invention prepares a dense diffusion barrier layer using a controlled atmosphere spraying process, which is used to suppress the migration of easily oxidized elements from the substrate to the surface under high-temperature service conditions, and is suitable for high-temperature components such as aero-engine blades and nuclear reactor components. Detailed Implementation

[0022] This invention provides a method for preparing an anti-oxidation coating from the inside out, comprising the following steps:

[0023] A) Prepare an MCrAlY alloy layer on a pretreated substrate surface, wherein M is selected from one or more of Ni, Co, or Fe;

[0024] B) Spraying MCrAlY powder and nano-ceramic powder onto the surface of the MCrAlY alloy layer to obtain a nanocrystalline composite layer;

[0025] C) The nanocrystalline composite layer is laser-remelted and then cooled to obtain an antioxidant coating.

[0026] The present invention first pretreats the matrix, the pretreating process including the following steps:

[0027] The substrate surface is sandblasted to achieve a surface roughness Ra of 3~5μm.

[0028] Then, the pretreated substrate is placed in a spraying chamber, evacuated to 0.1 Pa, and then filled with high-purity Ar. The oxygen content in the spraying chamber is ≤10ppm.

[0029] Next, a NiCrAlY alloy layer was prepared on the pretreated substrate surface by spraying metal alloy powder with supersonic flame.

[0030] The flame temperature of the supersonic flame spraying is 2600-3000℃, which can be any value between 2600, 2650, 2700, 2750, 2800, 2850, 2900, 2950, ​​3000, or 2600-3000℃. The powder feeding rate is 30-70 g / min, which can be any value between 30, 40, 50, 60, 70, or 30-70 g / min.

[0031] The metal alloy powder is an MCrAlY type alloy, where M is selected from one or more of Ni, Co, or Fe. Preferably, the metal alloy powder is a NiCrAlY type alloy. The particle size of the metal alloy powder is 10-53 μm, and can be any value between 10, 20, 30, 40, 50, 53, or 10-53 μm.

[0032] The thickness of the obtained MCrAlY alloy layer is 40~80μm, which can be any value between 40, 45, 50, 55, 60, 65, 70, 75, 80, or 40~80μm.

[0033] Then, while continuously spraying metal alloy powder, nano-ceramic powder is fed in to form a nanocrystalline composite layer on the surface of the MCrAlY alloy layer.

[0034] The nano-ceramic powder is selected from one or more of rare earth oxide-stabilized zirconium oxide, alumina, and spinel-type oxides, preferably Y2O3-ZrO2 powder.

[0035] The particle size of the nano-ceramic powder is 20~200nm, and can be any value between 20, 40, 50, 60, 80, 100, 120, 140, 150, 160, 180, 200, or 20~200nm.

[0036] The volume percentage of the nano-ceramic powder to the total volume of MCrAlY powder and nano-ceramic powder is 15% to 40%, and can be any value between 15%, 20%, 25%, 30%, 35%, 40%, or 15% to 40%.

[0037] The thickness of the obtained nanocrystalline composite layer is 20~60μm, which can be any value between 20, 25, 30, 35, 40, 45, 50, 55, 60, or 20~60μm.

[0038] Then, the nanocrystalline composite layer is laser remelted, that is, the surface of the coating is scanned with a laser beam. The power of the laser beam for laser remelting is 2~2.8kW, which can be any value between 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, or 2~2.8kW.

[0039] After laser remelting, non-porous nano-equiaxed crystals are formed within a depth of 5-20 μm on the surface of the coating. The depth of the non-porous nano-equiaxed crystals can be 5, 7, 10, 12, 14, 15, 16, 18, 20, or any value between 5 and 20 μm.

[0040] Finally, a post-treatment is performed to obtain a high-temperature antioxidant coating. The post-treatment is aerosol cooling, and the aerosol cooling temperature is below 200°C.

[0041] The present invention also provides a high-temperature antioxidant coating prepared by the above preparation method, wherein the thickness of the high-temperature antioxidant coating is 80~120μm, which can be any value between 80, 90, 100, 110, 120, or 80~120μm, and the porosity is <2%.

[0042] The present invention also provides a high-temperature antioxidant coating preparation system, comprising: a sealed spraying chamber, a high-speed flame spraying system, a powder supply device, an in-situ laser irradiation device, and a substrate preheating / cooling system.

[0043] Specifically, the high-temperature antioxidant coating preparation system provided by the present invention includes:

[0044] The high-temperature antioxidant coating preparation system provided by this invention mainly includes:

[0045] Sealed spray coating chamber: This chamber can be evacuated and filled with an inert protective gas to ensure that the internal oxygen content is maintained at a low level. The chamber walls are preferably integrated with a water cooling system. The inert protective gas is selected from argon or nitrogen; the oxygen content inside the sealed spray coating chamber is ≤10 ppm.

[0046] High-speed flame spraying system: This system consists of a spray gun and a fuel and gas control unit. The spray gun extends directly into and is fixed within a sealed spraying chamber, generating a supersonic flame stream inside. The connected powder supply device preferably includes at least two independent powder feeders for separately conveying metal alloy powder and nano-ceramic powder, with independently adjustable powder feeding rates.

[0047] In-situ laser irradiation device: The laser head of this device is integrated into the sealed spraying chamber through an optical window or directly built-in, and is located behind the spray gun. Its function is to quickly scan the newly deposited coating immediately after the spraying process to achieve laser remelting. The in-situ laser irradiation device is located downstream of the spray flow and uses a fiber laser to instantaneously remelt the deposited coating. The fiber laser has a wavelength of 1070 nm and a power of 1-3 kW. The laser beam axis of the laser irradiation device forms an angle of 15°-30° with the spray flow axis, which can be any value between 15°, 20°, 25°, 30°, or 15°-30°.

[0048] Substrate preheating and cooling system: The preheating components (such as induction heating coils or infrared heating plates) and cooling components (such as multiple sets of aerosol cooling nozzles) of this system are both located inside the chamber and act directly on the workpiece fixture supporting the substrate, achieving precise control of the substrate temperature. The maximum heating temperature of the preheating components is 800℃. The cooling rate of the aerosol cooling nozzles is controllable.

[0049] This invention utilizes a diffusion-blocking mechanism to suppress the migration of easily oxidized elements from the matrix to the surface of a high-temperature anti-oxidation coating under high-temperature service conditions. Specifically, the high grain boundary density of the nanocrystalline composite layer in the coating significantly hinders the diffusion of elements such as Cr / Ti, reducing the diffusion coefficient to 1×10⁻⁶. -16 m 2 The coating speed is two orders of magnitude lower than that of traditional coatings. The resulting high-temperature antioxidant coating has a hardness ≥1200 HV0.3, a porosity <1.5%, and no Cr-depleted areas in the substrate after oxidation at 1600℃ for 100 h. The high-temperature antioxidant coating provided by this invention can achieve a single spraying thickness of up to 100 μm, with an efficiency more than 5 times higher than that of PVD / CVD processes.

[0050] To further understand the present invention, the following description, in conjunction with embodiments, illustrates the high-temperature antioxidant coating, its preparation method, and its preparation apparatus provided by the present invention. The scope of protection of the present invention is not limited by the following embodiments.

[0051] Example 1

[0052] 1. Sandblast the IN718 alloy blades, install them in the spraying chamber, and fill them with Ar (O2<5ppm) after vacuuming.

[0053] 2. The substrate is induction heated to 650°C, and a NiCrAlY layer (60 μm thick) is sprayed using HVOF spraying; the flame temperature of the supersonic flame spraying is 2800°C, and the powder feeding rate is 50 g / min.

[0054] 3. Switch the powder feeder and simultaneously spray NiCrAlY (particle size 15-45μm) + 20 vol% Y2O3-ZrO2 nanoparticles (particle size 50-100μm) to form a composite layer (thickness 40 μm).

[0055] 4. Laser remelting, power 2.5 kW, scanning speed 10 mm / s. After laser remelting, non-porous nano-equiaxed crystals are formed within a depth of 10 μm on the surface of the coating.

[0056] 5. Cool the aerosol (N2 + 20% H2O) to 150℃.

[0057] Examples 2-4

[0058] Following the method of Example 1, the process parameters were modified (see Table 1 for details) to obtain a high-temperature antioxidant coating.

[0059] Table 1

[0060]

[0061] Test case

[0062] 1. The thickness and porosity of the coating were tested using a scanning electron microscope;

[0063] 2. The hardness of the coating was tested using a Vickers microhardness tester;

[0064] 3. Thermal cycling test - test the coating with 1100℃ thermal shock cycling;

[0065] 4. High-temperature oxidation test;

[0066] 5. Determination of diffusion coefficient;

[0067] 6. Oxidize at 1600℃ for 100 h.

[0068] Table 2

[0069]

[0070] This invention utilizes an inert atmosphere composite spraying technique combined with in-situ laser remelting to prepare a dense nanocrystalline coating with a thickness of 80-120 μm on the substrate surface. This coating, through its high-density grain boundaries, blocks the outward diffusion of easily oxidized elements from within the substrate, significantly improving the service life of components in extreme environments above 1400℃. Furthermore, the fabrication apparatus provided by this invention has high integration and is suitable for complex curved surface components such as aero-engine blades.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature antioxidant coating, characterized in that, Includes the following steps: A) Prepare an MCrAlY alloy layer on a pretreated substrate surface, wherein M is selected from one or more of Ni, Co, or Fe; B) Spraying MCrAlY powder and nano-ceramic powder onto the surface of the MCrAlY alloy layer to obtain a nanocrystalline composite layer; C) The nanocrystalline composite layer is laser remelted and then post-processed to obtain a high-temperature anti-oxidation coating.

2. The preparation method according to claim 1, characterized in that, In step A), a metal alloy powder is sprayed using a supersonic flame to prepare an MCrAlY alloy layer on the pretreated substrate surface.

3. The preparation method according to claim 2, characterized in that, The flame temperature of the supersonic flame spraying is 2600-3000℃, and the powder feeding rate is 30-70g / min; The metal alloy powder is an MCrAlY type alloy, and the particle size of the metal alloy powder is 10-53 μm.

4. The preparation method according to claim 1, characterized in that, The thickness of the MCrAlY alloy layer is 40~80μm.

5. The preparation method according to claim 1, characterized in that, The nano-ceramic powder is selected from one or more of rare earth oxide-stabilized zirconium oxide, alumina, and spinel-type oxides, preferably Y2O3-ZrO2 powder. The particle size of the nano-ceramic powder is 20~200nm.

6. The preparation method according to claim 1, characterized in that, The volume of the nano-ceramic powder accounts for 15% to 40% of the total volume of the MCrAlY powder and the nano-ceramic powder.

7. The preparation method according to claim 1, characterized in that, The power of the laser beam used for laser remelting is 2~2.8kW.

8. The preparation method according to claim 1, characterized in that, After laser remelting, non-porous nano-equiaxed crystals are formed within a depth of 5~20μm on the surface of the coating.

9. The preparation method according to claim 1, characterized in that, The post-processing is aerosol cooling, and the aerosol cooling temperature is below 200°C.

10. A high-temperature antioxidant coating prepared by the preparation method according to any one of claims 1 to 9, characterized in that, The thickness of the high-temperature antioxidant coating is 80~120μm, and the porosity is <2%.

11. A system for preparing a high-temperature antioxidant coating, characterized in that, include: Sealed spraying chamber, high-speed flame spraying system, powder supply module, in-situ laser irradiation module, substrate preheating / cooling system.

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