MCrAlY alloy powder with high sphericity degree as well as preparation method and application of MCrAlY alloy powder

Abstract

The invention provides MCrAl alloy powder with the high sphericity degree and a preparation method and application of the MCrAl alloy powder. The preparation method comprises the following steps: (1) performing vacuum melting and casting molding on an MCrAlY alloy raw material to obtain an alloy blank; and (2) the alloy blank is clamped into plasma rotating electrode powder manufacturing equipment, vacuumizing is conducted firstly, then protective gas is introduced, then powder manufacturing is conducted, and the MCrAlY alloy powder with the high sphericity degree is obtained. Wherein the powder preparation parameters comprise the following conditions: the working current of equipment is 750A-950A; the feeding speed of the alloy blank ranges from 2.0 mm / s to 2.5 mm / s, and the rotating speed ranges from 28000 rpm to 38000 rpm; according to the MCrAlY alloy powder with the high sphericity degree prepared through the preparation method of the MCrAlY alloy powder with the high sphericity degree, the oxygen content is lower than 0.01%, the sphericity degree is larger than 95%, and the mass ratio of powder with the particle size smaller than 106 micrometers is larger than or equal to 72%. According to the preparation method disclosed by the invention, the preparation of the thermal spraying MCrAlY bonding layer alloy powder which is low in oxygen content, low in satellite sphere proportion and high in flowability is realized by controlling various process parameters of powder preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of bond coat powders for thermal barrier coatings, in particular to a high-sphericity MCrAlY alloy powder and a preparation method and application thereof. BACKGROUND

[0002] Thermal barrier coatings (TBCs) are a key technology for protecting the surfaces of high-temperature components such as aero-engines and gas turbines, and their performance directly determines the service life of the equipment in extreme temperature, oxidation and corrosion environments. The bond coat, as a core component of the thermal barrier coating, needs to have excellent oxidation resistance, hot corrosion resistance and good bonding force with the substrate material. MCrAlY (M is Ni, Co or a combination thereof) alloy has become the mainstream bond coat material because it can form a dense Al2O3 protective film at high temperatures.

[0003] However, the performance of the bond coat is closely related to the morphology, particle size distribution and sphericity of the MCrAlY powder used: high-sphericity powder can significantly improve the density of the sprayed coating, reduce porosity, and improve powder flowability, thereby reducing the risk of stress and crack initiation in the coating and prolonging the service life of the component.

[0004] The performance of the bond coat of the thermal barrier coating is highly dependent on the preparation process of the MCrAlY alloy powder. Traditional gas atomization method prepares powder by breaking the molten metal stream with high-pressure gas, but the process characteristics of this method result in inherent defects in the powder: 1) High-speed airflow impact can cause secondary collision of incompletely solidified droplets, forming satellite ball adhesion, which significantly reduces the sphericity of the powder; 2) Gas entrainment and imbalance of droplet surface tension can produce hollow powder, and the particle size distribution of the powder is discrete, which seriously affects the density and composition uniformity of the coating; 3) Al element is easily oxidized and burned during rapid solidification, causing composition segregation and impurity phase generation, thereby weakening the continuity and integrity of the Al2O3 protective film. SUMMARY

[0005] The present application provides a high-sphericity MCrAlY bond coat alloy powder based on plasma rotating electrode technology and a preparation method and application thereof to solve the problems of low sphericity, poor flowability and high satellite ball ratio of the bond coat alloy powder.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows: This invention provides a method for preparing high-sphericity MCrAlY alloy powder, comprising: (1) vacuum melting and casting MCrAlY alloy raw materials to obtain an alloy billet; (2) clamping the alloy billet into a plasma rotating electrode powder making device, first evacuating the vacuum and then introducing a protective gas, and then performing powder making to obtain the high-sphericity MCrAlY alloy powder; wherein, the powder making parameters include: the device operating current is 750A~950A; the alloy billet feed speed is 2.0mm / s~2.5mm / s, and the rotation speed is 28000rpm~38000rpm; the high-sphericity MCrAlY alloy powder obtained by the method of preparing high-sphericity MCrAlY alloy powder has an oxygen content of less than 0.01%, a sphericity of greater than 95%, and a mass ratio of powder with a particle size of less than 106μm greater than or equal to 72%.

[0007] This invention first evacuates the plasma rotating electrode powder making equipment, and then introduces a protective gas into the plasma rotating electrode powder making working chamber to ensure that the plasma rotating electrode powder making process is not affected by other gases, effectively reducing the oxygen content in the alloy powder; this invention achieves the preparation of high sphericity powder by controlling process parameters such as the equipment operating current, bar feed speed and rotation speed in the powder making process.

[0008] Specifically, when the plasma rotating electrode powder making equipment is working, by adjusting the rod rotation speed (28000rpm~38000rpm) and feed speed (2.0mm / s~2.5mm / s), the size of the molten droplets is made uniform and the powder is formed quickly, which significantly reduces the risk of collision and adhesion, and ensures that the molten droplets form highly spherical powder under the full effect of surface tension.

[0009] It can be seen that the above process and operating parameters can ensure that the MCrAlY alloy powder with high sphericity is very suitable for thermal spraying process in terms of oxygen content, sphericity and particle size. In particular, the proportion of powder with a particle size of less than 106μm is greater than 72% by mass, which makes the vast majority of the powder suitable for thermal spraying feeding requirements.

[0010] Furthermore, in step (2), the process of first evacuating the vacuum and then introducing the protective gas specifically involves: first evacuating the vacuum until the vacuum level is less than 1×10⁻⁶. -3 Pa, and then a protective gas is introduced until the pressure is less than or equal to 0.05 MPa. This ensures that the plasma rotating electrode powder preparation process is not affected by other gases, reducing the oxygen content of the MCrAlY alloy powder.

[0011] Furthermore, in step (2), the protective gas is argon, the gas flow rate is 6L / min~7L / min, and the gas introduction time is 1.5min~2min.

[0012] Furthermore, step (1) specifically includes: first, vacuum melting the MCrAlY alloy raw material, then casting it into a rod shape and finishing it to the target size to obtain an alloy billet; wherein, the parameters of the vacuum melting include: the vacuum degree during melting is less than or equal to 5.0 × 10⁻⁶. -2 Pa, casting temperature is 1380℃~1400℃.

[0013] Furthermore, the finishing process is as follows: rough turning, finish turning, grinding, straightening are performed sequentially, and threading is performed at the clamping end.

[0014] Furthermore, the target dimensions are a diameter of 28mm~30mm and a length of 150mm~160mm.

[0015] Furthermore, after grinding, the process also includes sieving the resulting powder.

[0016] The present invention also provides high sphericity MCrAlY alloy powder prepared by the above-mentioned method for preparing high sphericity MCrAlY alloy powder.

[0017] Furthermore, the mass percentage of the MCrAlY alloy powder with a particle size of less than 106 μm is greater than 80%.

[0018] This invention provides the application of the above-mentioned high sphericity MCrAlY alloy powder as a binder material in the field of thermal spraying.

[0019] The technical solution provided by this invention has at least the following advantages: This invention provides a high-sphericity MCrAlY alloy powder based on plasma rotating electrode technology and its preparation method. The method involves clamping processed MCrAlY rods into the vacuum chamber of a plasma rotating electrode powder-making device for powder preparation. By adjusting various process parameters, stable preparation of a high-sphericity thermally sprayed MCrAlY binder layer powder is achieved.

[0020] Compared to the physical limitations of traditional gas atomization processes, which are constrained by the impact of high-speed airflow, plasma rotating electrode technology achieves a breakthrough in binder powder performance through the synergistic effect of a self-driven centrifugal peeling mechanism and surface tension-driven solidification kinetics. Specifically, this manifests in: 1) Precise morphology control: High-speed centrifugal force causes molten metal droplets to separate uniformly in a monodisperse mode, eliminating satellite sphere adhesion. The powder sphericity is significantly higher than that of gas-atomized binder powders, resulting in lower surface roughness and significantly improved spray flowability and deposition efficiency; 2) Enhanced structural density: Droplets freely shrink and form under inert gas protection, resulting in a low internal cavity defect rate and fundamentally avoiding the risks of abnormal coating porosity and crack propagation; 3) Enhanced compositional fidelity: Low oxygen increment throughout the powder preparation process effectively reduces Al element burn-off rate, ensuring that the MCrAlY alloy composition strictly matches the design value. These technological advantages are particularly suitable for advanced binder systems, providing highly consistent powder materials for thermal spraying processes. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0022] Figure 1 SEM image of MCrAlY alloy powder with high sphericity provided in an embodiment of the present invention.

[0023] Figure 2 SEM cross-sectional image of MCrAlY alloy powder with high sphericity provided in an embodiment of the present invention.

[0024] Figure 3 The image shows the SEM cross-sectional morphology of the thermal barrier coating adhesive layer prepared with the highly spherical MCrAlY alloy powder provided in the embodiments of the present invention. Detailed Implementation

[0025] The present invention will now be described in detail with reference to specific embodiments.

[0026] Example 1 Step 1: The MCrAlY alloy bar obtained by vacuum melting is precision machined; the composition of the MCrAlY alloy bar is NiCoCrAlY, which includes the following by mass percentage: Ni: 50.2%, Co: 21.0%, Cr: 18.5%, Al: 10.0%, Y: 0.3%, and the sum of the mass percentages of each component is 100%; the precision machining process is as follows: rough turning, fine turning, grinding, straightening, and thread machining at the clamping end.

[0027] Step 2: Clamp the MCrAlY alloy rods, which have undergone precision machining in Step 1, into the rod assembly position of the plasma rotating electrode powder making equipment, and evacuate the working chamber of the plasma rotating electrode powder making equipment to a vacuum level below 1.0 × 10⁻⁶. - 3 Pa; Step 3: Introduce protective gas into the working chamber of the plasma rotating electrode powder making equipment after vacuuming in Step 2, and then start the plasma rotating electrode powder making equipment to prepare alloy powder from the refined alloy rod. During the alloy powder making process, the working current of the plasma rotating electrode powder making equipment is 800A, the alloy rod feeding speed is 2.0mm / s, the initial rotation speed of the alloy rod is 28000rpm, and the stable rotation speed is 38000rpm. The protective gas in the working chamber consists of argon and helium in a volume ratio of 3:1. Step 4: After cooling the alloy powder obtained in Step 3, sieve it and then encapsulate it to obtain thermally sprayed MCrAlY binder alloy spherical powder.

[0028] Testing revealed that the oxygen content of the alloy spherical powder prepared in this embodiment was less than 0.01%, the sphericity was greater than 95%, and the mass percentage of powder with a particle size of less than 106 μm was greater than 72%.

[0029] Example 2 This embodiment includes the following steps: Step 1: The MCrAlY alloy bar obtained by vacuum melting is precision machined; the composition of the MCrAlY alloy bar is NiCoCrAlY, which includes the following components by mass percentage: Ni: 50.2%, Co: 21.0%, Cr: 18.5%, Al: 10.0%, Y: 0.3%, and the sum of the mass percentages of each component is 100%; the precision machining process is as follows: rough turning, fine turning, grinding, straightening, and thread machining at the clamping end. Step 2: Clamp the MCrAlY alloy rods, which have undergone precision machining in Step 1, into the rod assembly position of the plasma rotating electrode powder making equipment, and evacuate the working chamber of the plasma rotating electrode powder making equipment to a vacuum level below 1.0 × 10⁻⁶. - 3 Pa; Step 3: Introduce protective gas into the working chamber of the plasma rotating electrode powder making equipment after vacuuming in Step 2, and then start the plasma rotating electrode powder making equipment to prepare alloy powder from the refined alloy rod. During the alloy powder making process, the working current of the plasma rotating electrode powder making equipment is 900A, the alloy rod feeding speed is 2.5mm / s, the initial rotation speed of the alloy rod is 28000rpm, and the stable rotation speed is 38000rpm. The protective gas in the working chamber consists of argon and helium in a volume ratio of 3:1. Step 4: After cooling the alloy powder obtained in Step 3, sieve it and then encapsulate it to obtain thermally sprayed MCrAlY binder alloy spherical powder.

[0030] Testing revealed that the alloy spherical powder prepared in this embodiment had an oxygen content of less than 0.01%, a sphericity of greater than 95%, and a mass percentage of powder with a particle size of less than 106 μm greater than 80%.

[0031] Figure 1 This is a SEM image of the thermally sprayed MCrAlY binder alloy spherical powder prepared in Example 2. Figure 1 As can be seen from the above, the thermally sprayed MCrAlY binder alloy spherical powder prepared in this embodiment has high sphericity, uniform size, and no satellite spheres.

[0032] Figure 2 This is a SEM cross-sectional image of the thermally sprayed MCrAlY binder alloy spherical powder prepared in Example 2. Figure 2 As can be seen from the image, the thermally sprayed MCrAlY binder alloy spherical powder prepared in this embodiment has a solid spherical structure and high density.

[0033] Figure 3 The SEM cross-sectional morphology of the thermal barrier coating adhesive layer prepared from the thermally sprayed MCrAlY adhesive alloy spherical powder prepared in Example 2 is shown below. Figure 3 As can be seen, the thermal barrier coating binder layer composed of the thermally sprayed MCrAlY binder alloy spherical powder prepared in this embodiment exhibits a typical layered structure of thermally sprayed coatings. This typical layered structure of thermally sprayed coatings is formed by the rapid spread, solidification, and layer-by-layer accumulation of powder particles heated to molten by the heat source impacting the substrate at high speed during the thermal spraying process. Each layer is composed of flattened particles stacked on top of each other, and the layers are tightly bonded together.

[0034] In summary, the present invention provides a method for preparing a high-sphericity thermally sprayed MCrAlY binder alloy powder, which reconstructs the powder forming mechanism from the source of the process using plasma rotating electrode technology. Its core features are: 1) High-speed rotating electrode centrifugal force autonomously peels away molten metal, achieving precise control of monodisperse droplets, completely eliminating satellite sphere adhesion, and increasing powder sphericity to over 98%; 2) The synergistic effect of vacuum inert environment and centrifugal force ensures free shrinkage and forming of droplets, reducing the hollow powder rate and resulting in uniform and concentrated particle size distribution; 3) The short-process design of electrode melting-centrifugal separation enables atomic-level diffusion homogenization of alloying elements during sub-second condensation, improving Al element retention and fundamentally avoiding impurity phase precipitation, significantly breaking through the performance boundaries of existing gas-atomized powders.

[0035] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the present invention. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing MCrAlY alloy powder with high sphericity, characterized in that, include: (1) The MCrAlY alloy raw material is vacuum melted and cast to obtain an alloy billet; (2) The alloy billet is clamped into the plasma rotating electrode powder making equipment, a vacuum is first drawn and then a protective gas is introduced, and then powder making is carried out to obtain the MCrAlY alloy powder with high sphericity. The parameters for powder preparation include: the operating current of the equipment is 750A~950A; the feeding speed of the alloy billet is 2.0mm / s~2.5mm / s; and the rotation speed is 28000rpm~38000rpm. The MCrAlY alloy powder with high sphericity prepared by the aforementioned method has an oxygen content of less than 0.01%, a sphericity of greater than 95%, and a mass percentage of powder with a particle size of less than 106 μm of greater than or equal to 72%.

2. The method for preparing high sphericity MCrAlY alloy powder according to claim 1, characterized in that, In step (2), the process of first evacuating the vacuum and then introducing the protective gas specifically involves: first evacuating the vacuum until the vacuum level is less than 1×10⁻⁶. -3 Pa, then introduce protective gas until the pressure is less than or equal to 0.05 MPa.

3. The method for preparing high sphericity MCrAlY alloy powder according to claim 1, characterized in that, In step (2), the protective gas is argon, the flow rate is 6L / min to 7L / min, and the inlet time is 1.5min to 2min.

4. The method for preparing high sphericity MCrAlY alloy powder according to claim 1, characterized in that, The specific steps (1) include: first, vacuum melting the MCrAlY alloy raw material, then casting it into a rod shape and finishing it to the target size to obtain an alloy billet; The parameters for vacuum melting include: a vacuum degree of less than or equal to 5.0 × 10⁻⁶ during melting. -2 Pa, casting temperature is 1380℃~1400℃.

5. The method for preparing high sphericity MCrAlY alloy powder according to claim 4, characterized in that, The finishing process is as follows: rough turning, fine turning, grinding, straightening are performed in sequence, and threading is performed at the clamping end.

6. The method for preparing high sphericity MCrAlY alloy powder according to claim 4, characterized in that, The target dimensions are 28mm~30mm in diameter and 150mm~160mm in length.

7. The method for preparing high sphericity MCrAlY alloy powder according to claim 1, characterized in that, After grinding, the process also includes sieving the resulting powder.

8. A method for preparing high sphericity MCrAlY alloy powder according to any one of claims 1 to 7.

9. The high sphericity MCrAlY alloy powder according to claim 8, characterized in that, The high sphericity MCrAlY alloy powder contains more than 80% by mass of powder with a particle size of less than 106 μm.

10. The application of the high sphericity MCrAlY alloy powder according to claim 8 as a binder material in the field of thermal spraying.

Images