A CMAS standard sphere based on pneumatic pore coordination and a preparation method and application thereof

Abstract

This invention discloses a CMAS standard sphere based on pneumatic pore synergy, its preparation method, and its application. The method includes: weighing the required mass of original CMAS powder and placing it in a tablet mold; pressing it into a blank under a pressure of 10-100 MPa, forming a connected venting micropore structure inside the blank; placing the blank in a non-contact, stable suspension device; using a laser heating device to rapidly heat the blank to 1800-2000℃ in a single step within 20-40 seconds, causing the internal gas to spontaneously and instantly escape through the venting micropore structure before surface liquefaction and sealing, melting to form bubble-free spherical droplets; turning off the laser heating device and rapidly cooling and solidifying the molten droplets to obtain the CMAS standard sphere. The CMAS standard sphere prepared by this method has a sphericity ≥0.95, a composition highly consistent with the original CMAS, and features a simplified process, low energy consumption, and high efficiency. It provides an ideal standard test sample for the high-temperature spreading and wetting kinetics study of thermal barrier coatings and environmental barrier coatings, and has good application prospects.

Description

Technical Field

[0001] This invention relates to the field of high-temperature ceramic materials and coating performance testing technology, specifically to a CMAS standard sphere based on aerodynamic pore synergy, its preparation method, and its application. Background Technology

[0002] Thermal barrier coatings for aero-engines are susceptible to corrosion from environmental deposits during high-temperature service environments, with calcium magnesium aluminum silicate (CaO-MgO-Al2O3-SiO2, CMAS) being a typical example. When CMAS melts at high temperatures, it spreads across the coating surface and penetrates into the coating interior, leading to structural degradation and even failure. Studying the spreading and wetting kinetics of CMAS melt on the surface of thermal barrier coatings is crucial for elucidating the corrosion mechanism.

[0003] Traditional crucible melting and crushing methods produce CMAS particles with irregular shapes, leading to significant differences in the initial contact state during spreading experiments and resulting in large experimental errors. In recent years, air-suspended laser heating technology has been introduced into the preparation of CMAS materials. For example, Chinese patent CN119569313A discloses a method for preparing multi-scale sediment particles, which uses air suspension combined with laser heating to prepare spherical CMAS particles. However, this patented method still has significant drawbacks:

[0004] (1) To prevent the airflow from blowing away the powder tablets, the powder is first pressed into a high-strength blank under high pressure (300-500 MPa). However, the high pressure causes the pores inside the blank to be almost completely closed, blocking the exhaust channels. Even if there are a few residual isolated pores, during the laser heating process, the surface of the blank will melt first and quickly form a dense liquid film or shell under the action of surface tension, completely sealing these pores, making it difficult for the internal gas to escape and easily forming bubbles.

[0005] (2) In order to eliminate bubbles to the greatest extent, this method has to rely on repeated thermal shock cycles of "heating-cooling-heating". This operation has many problems: First, the process is complicated, the preparation efficiency is low and the production energy consumption is high; second, for CMAS materials containing low melting point components, repeated high temperature exposure will aggravate the loss of volatile components (such as alkali metals), making it difficult to ensure the high fidelity of the original CMAS composition; third, repeated thermal shock cycles also make it difficult to ensure the high sphericity of the particles, and particles with insufficient sphericity will produce irregular contact interfaces in the early stage of spreading, which makes it difficult for the current advanced coating life prediction model to converge in complex numerical simulations or produce large systematic errors, and cannot meet the requirements of high-precision boundary conditions. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a CMAS standard sphere based on pneumatic pore synergy, its preparation method and application. By controlling the pore structure of the preform and optimizing the air suspension heating process, a high-fidelity and high-sphericity CMAS standard sphere can be prepared in one step without repeated thermal shock, so as to meet the high precision requirements of the standard sphere in numerical simulation of coating spreading and wetting dynamics testing.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] The first aspect of this invention provides a method for preparing CMAS standard spheres based on aerodynamic pore synergy, comprising the following steps:

[0009] S1, Calculate the required mass of CMAS raw powder based on the density of the raw CMAS powder and the particle size of the target CMAS standard spheres;

[0010] S2, Weigh the required mass of CMAS raw powder and place it in a tableting mold, press it into a blank with a pressure of 10-100 MPa, so that the interior of the blank forms a connected exhaust micropore structure.

[0011] S3, the billet is placed in an air suspension device, and the billet is kept in a stable suspension state without contact by the flow of suspended gas.

[0012] S4, using a laser heating device to heat the suspended billet, the billet is rapidly heated to 1800-2000℃ in one step within 20-40 seconds, so that the gas inside it is spontaneously discharged in one go through the exhaust micropore structure before the surface is completely liquefied and sealed. Then the billet is completely melted to form bubble-free spherical droplets.

[0013] S5, turn off the laser heating device to allow the molten spherical droplets to cool and solidify rapidly in a suspended state, thereby obtaining CMAS standard spheres with the target particle size.

[0014] Preferably, the CMAS raw powder is selected from any one of artificially synthesized CMAS powder, sand, volcanic ash, dust or other natural environmental sediments.

[0015] Preferably, when the particle size of the target CMAS standard sphere is less than 2 mm, the pressure applied to the pressed blank is 10-40 MPa and the holding time is 5-10 min; when the particle size of the target CMAS standard sphere is greater than or equal to 2 mm, the pressure applied to the pressed blank is 40-100 MPa and the holding time is 10-15 min.

[0016] Preferably, the suspended gas is selected from any one of air, oxygen, nitrogen, or argon.

[0017] Preferably, the suspended gas is oxygen.

[0018] Preferably, the flow rate of the suspended gas is 0.8-1.5 L / min.

[0019] Preferably, during the single-step flash heating process, the heating rate is 45-100℃ / s, and the holding time after reaching the target temperature is 10-30 s.

[0020] A second aspect of the present invention provides a CMAS standard sphere prepared by the above-described preparation method.

[0021] Preferably, the CMAS standard spheres are glassy spheres with a particle size of 1.0-3.5 mm and a sphericity ≥0.95.

[0022] A third aspect of the present invention provides an application of the above-mentioned CMAS standard sphere in high-temperature spreading and / or wetting kinetics testing of thermal barrier coatings and / or environmental barrier coatings.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) This invention employs a low-pressure pressing process of 10-100 MPa, which ensures that the green body has sufficient mechanical strength to resist the impact of air suspension flow without disintegration, while retaining an interconnected network of exhaust micropores inside the green body. Based on this, this invention uses single-step flash heating (heating to 1800-2000℃ in one go within 20-40 s) to allow the internal gas to be discharged along the interconnected micropores in one go before a closed liquid film is formed on the surface. This allows for the production of bubble-free spherical droplets and CMAS microspheres without any thermal shock cycles, significantly simplifying the process, reducing energy consumption, and improving preparation efficiency.

[0025] (2) The CMAS microspheres of different particle sizes prepared by the method of the present invention have a true sphericity of more than 0.95 and their composition is highly faithful to that of the original natural CMAS. They provide a high-fidelity standard sample with both ideal spherical boundary conditions and real composition for the high-temperature spreading and wetting kinetics study of thermal barrier coatings and environmental barrier coatings, and have good application prospects. Attached Figure Description

[0026] Figure 1 This is a schematic flowchart of the CMAS standard sphere preparation method based on aerodynamic pore synergy in Example 1;

[0027] Figure 2 This is a schematic diagram of the air-suspended laser heating device in Example 2;

[0028] Figure 3The CMAS microspheres with different particle sizes prepared in Examples 3-5 are shown, where A is the CMAS microsphere prepared in Example 3, B is the CMAS microsphere prepared in Example 4, and C is the CMAS microsphere prepared in Example 5.

[0029] Figure 4 This is a comparative schematic diagram of the high-temperature spreading process of CMAS microspheres prepared in Example 3 and traditional irregular CMAS particles on the surface of a thermal barrier coating. In this diagram, A represents traditional irregular CMAS particles, and B represents CMAS microspheres prepared in Example 3.

[0030] Figure 5 The cylindrical blanks obtained by pressing in Example 5 and Comparative Example 1 are shown, where A is the blank obtained by pressing in Comparative Example 1 and B is the blank obtained by pressing in Example 5.

[0031] Figure 6 The images shown are cross-sectional views of the cylindrical blanks obtained by pressing in Example 5 and Comparative Example 1, taken under an optical microscope. The red circled parts are the recessed pits below the plane. Among them, A is a cross-sectional view of the blank obtained by pressing in Comparative Example 1, and B is a cross-sectional view of the blank obtained by pressing in Example 5.

[0032] Figure 7 Actual photographs of the CMAS microspheres prepared in Example 5 and Comparative Example 1, where A is the CMAS microsphere prepared in Comparative Example 1 and B is the CMAS microsphere prepared in Example 5.

[0033] Figure 8 The images show the outlines of the CMAS microspheres prepared in Example 5 and Comparative Example 1, where A is the outline of the CMAS microspheres prepared in Comparative Example 1 and B is the outline of the CMAS microspheres prepared in Example 5.

[0034] Figure 9 A comparative composition diagram of the CMAS microspheres prepared from natural volcanic ash and those prepared in Example 5 and Comparative Example 1.

[0035] In the figure: 1. High temperature meter; 2. Controller; 3. CO2 laser; 4. Laser reflector; 5. CMAS preform; 6. Sample stage; 7. Gas cylinder; 8. Gas delivery pipe. Detailed Implementation

[0036] To make the objectives and technical solutions of this invention clearer and more complete, the invention will be further described in detail below with reference to embodiments. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Modifications or equivalent substitutions made by those skilled in the art based on their understanding of the technical solutions of this invention, without departing from the spirit and scope of the technical solutions of this invention, are all within the scope of protection of this invention.

[0037] Unless otherwise specified, all reagents and materials involved in the embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0038] Terminology Explanation:

[0039] Pneumatic pore synergy: In this invention, it refers to the formation of an interconnected network of exhaust micropores inside the billet by adjusting the pressing pressure of the billet. In the subsequent single-step flash heating process, the gas that is decomposed or entrained in the melt can use the micropore network as a priority channel to be discharged outward in one go and with high efficiency before the surface tension forms a closed liquid film. This process reflects the synergistic effect between "interconnected pore structure" and "gas dynamic behavior".

[0040] Single-step flash heating: In this invention, it refers to a heating method that completes the heating and melting in a very short time without relying on repeated thermal shock.

[0041] Sphericity: In this invention, sphericity is measured and calculated based on a two-dimensional optical microscopic projection image of the CMAS sphere. The specific measurement and calculation method is as follows: A two-dimensional projection image of the CMAS sphere is acquired; the area A and perimeter P of the projection region are extracted using image processing software; and then the sphericity S is calculated using the following formula:

[0042]

[0043] When the ball is a perfectly spherical object, its two-dimensional projection is a standard circle, and S = 1.

[0044] Example 1

[0045] See Figure 1 This embodiment provides a method for preparing CMAS standard spheres based on aerodynamic pore synergy, including the following steps:

[0046] Step S1: Calculate the required mass of CMAS raw powder based on the density of the raw CMAS powder and the particle size of the target CMAS standard spheres.

[0047] This step calculates the theoretically required mass of CMAS raw powder to be prepared based on the particle size of the target CMAS standard spheres and the density of the CMAS raw powder. CMAS raw powder can be obtained by thoroughly grinding artificially synthesized CMAS powder, sand, volcanic ash, dust, or other natural environmental deposits.

[0048] Step S2: Weigh the required mass of CMAS raw powder and place it in a tableting mold. Press it into a blank with a pressure of 10-100 MPa to form a connected exhaust micropore structure inside the blank.

[0049] Specifically, the weighed CMAS raw powder is placed into a tableting mold, and then placed on a tableting machine for pressurization and pressure holding. The pressurization pressure is 10-100 MPa, and the pressure holding time is preferably 5-15 min.

[0050] It should be noted that in existing air suspension preparation processes, ultra-high pressure of 300-500 MPa is often used to prevent the green body from disintegrating under the impact of strong airflow. However, this results in the green body's internal pores being almost completely closed, preventing gas from escaping. This embodiment, through repeated exploration, limits the pressure applied during green body pressing to 10-100 MPa. This pressure range allows the green body to achieve a balance between resisting airflow impact and retaining exhaust micropores. On one hand, this pressure is sufficient to generate adequate bonding strength between powder particles, ensuring the green body maintains structural integrity and is not blown away under subsequent suspension airflow. On the other hand, this pressure avoids excessive densification, allowing the green body to retain an interconnected network of exhaust micropores, providing a physical channel for gas to escape during the melting process.

[0051] It should be understood that the applied pressure can be adaptively adjusted according to the particle size of the target spheres. As a preferred embodiment, when the particle size of the target CMAS standard spheres is less than 2 mm, the applied pressure of the pressed blank is 10-40 MPa, and the holding time is 5-10 min; when the particle size of the target CMAS standard spheres is greater than or equal to 2 mm, the applied pressure of the pressed blank is 40-100 MPa, and the holding time is 10-15 min.

[0052] Step S3: Place the billet in the air suspension device, and use the flow of suspended gas to keep the billet in a stable, non-contact suspension state.

[0053] Specifically, in combination Figure 2As shown, after the preform is removed from the tableting mold, it is placed on the sample stage 6 of the air suspension device. The air suspension device sprays high-speed flowing suspended gas through nozzles, using aerodynamic principles to generate an upward lifting force on the preform, causing it to detach from the surface of the sample stage 6, achieving stable suspension without contact. This non-contact state eliminates the interference of the sample stage 6 surface on the molten droplets, providing the necessary physical space for the subsequent formation of highly spherical spheres.

[0054] In a preferred embodiment, the suspending gas in this step can be any one of air, oxygen, nitrogen, or argon, and the gas flow rate is preferably 0.8-1.5 L / min. Specifically, when simulating the oxidizing environment of an aero-engine is required, oxygen is used as the suspending gas. Using oxygen as the suspending gas allows the billet to be in an oxygen partial pressure environment consistent with the high-temperature oxidizing atmosphere of an actual aero-engine during the subsequent melting process. This results in CMAS standard spheres with surface conditions and compositional stability matching actual service conditions, making it particularly suitable for high-fidelity simulation of the oxidizing environment in subsequent high-temperature spreading kinetic tests.

[0055] Step S4: The suspended blank is heated using a laser heating device to rapidly heat the blank to 1800-2000℃ in a single step within 20-40 seconds, so that the gas inside is spontaneously and once discharged through the exhaust micropore structure before the surface is completely liquefied and sealed. Subsequently, the blank is completely melted to form bubble-free spherical droplets.

[0056] Specifically, in combination Figure 2 As shown, this step uses a CO2 laser 3 to heat the billet to 1800-2000℃ in a single step within 20-40 seconds, i.e., single-step flash heating, at which point the heating rate can reach 45-100℃ / s. It should be noted that in this embodiment, the billet temperature is rapidly raised above the melting point within an extremely short time of 20-40 seconds. Due to the extremely rapid heating rate, the inside and outside of the billet heat up almost simultaneously. The internal gas expands due to heat, generating a driving force for outward escape. Before a continuous dense liquid film forms on the surface of the billet, the gas can spontaneously escape along the interconnected micropore network reserved in step S2. If the heating rate in this step is too slow, the surface layer will melt before the interior, forming a closed liquid film or shell. The internal gas will then expand but have nowhere to go, inevitably forming bubbles. After holding at the target temperature for 10-30 seconds, the billet completely melts, forming bubble-free spherical droplets.

[0057] Step S5: Turn off the laser heating device to allow the molten spherical droplets to cool and solidify rapidly in a suspended state, thereby obtaining CMAS standard spheres with the target particle size.

[0058] Specifically, after the heat source is removed by turning off the laser heating device, the droplet is rapidly cooled at a rate of approximately 500 K / s in the suspended airflow. Due to the lack of contact with the sample stage 6 surface, the droplet naturally shrinks into a highly spherical shape under the action of surface tension, and then quickly solidifies and sets, ultimately obtaining a glassy CMAS standard sphere with no internal bubbles and high compositional fidelity.

[0059] Example 2

[0060] This embodiment provides an air-suspended laser heating device for the preparation method described in Embodiment 1. For example... Figure 2 As shown, the equipment mainly includes an air suspension device, a laser heating device, and a temperature measurement and control device.

[0061] Specifically, the air suspension device, which provides stable aerodynamic force to suspend the preform to be processed, includes a gas cylinder 7, a gas supply pipe 8, and a sample stage 6. The gas cylinder 7 serves as the gas source and is connected to the bottom inlet of the sample stage 6 via the gas supply pipe 8. A converging conical nozzle structure is located at the center of the sample stage 6. Airflow enters the sample stage 6 through the gas supply pipe 8 and is ejected upwards at high speed from the nozzle, forming a stable laminar flow field. The CMAS preform 5 to be prepared is placed above the nozzle of the sample stage 6, achieving non-contact levitation using the aerodynamic lifting force generated by the airflow.

[0062] The laser heating device is used for non-contact heating of samples in a suspended state. It includes a CO2 laser 3 and a laser reflector 4. The CO2 laser 3 serves as a heat source and emits a laser beam under the control of the controller 2. One or more sets of laser reflectors 4 (or optical path guiding components) are arranged in the laser beam path to adjust the laser transmission path and precisely guide and focus the laser beam onto the surface of the suspended CMAS preform 5.

[0063] A temperature measurement and control device is used to achieve closed-loop temperature control, comprising a pyrometer 1 and a controller 2. The pyrometer 1 (preferably a bicolor pyrometer in this embodiment) is positioned diagonally above the CMAS preform 5 for non-contact real-time monitoring of the sample's surface temperature. The data output terminal of the pyrometer 1 is connected to the signal input terminal of the controller 2, transmitting the collected temperature signal to the controller 2. The control output terminal of the controller 2 is connected to a CO2 laser 3. The controller 2 has a pre-set PID control program that dynamically adjusts the output power of the CO2 laser 3 based on the difference between the real-time temperature fed back by the pyrometer 1 and the set temperature, thereby achieving precise temperature control of the CMAS preform 5.

[0064] The preparation method described above will be further illustrated by specific examples below.

[0065] Example 3: Preparation and Testing Application of Small-sized Glassy CMAS Microspheres

[0066] In this embodiment, glassy CMAS microspheres with a diameter of approximately 1.5 mm were prepared, and their spreadability was tested. The specific steps are as follows:

[0067] (1) Using natural volcanic ash as the raw powder for CMAS, approximately 4.0 mg of natural volcanic ash powder was weighed according to the density of natural volcanic ash. The powder was placed in a tableting mold and pressed into a cylindrical blank by applying a pressure of 10 MPa for 5 min.

[0068] (2) Place the billet above the nozzle of the sample stage 6 of the air suspension device, introduce high-purity oxygen, and control the flow rate to 1.0 L / min to make the billet suspend stably.

[0069] (3) Start the CO2 laser 3 and heat the billet to 1800℃ continuously within 25 s at an average heating rate of about 72℃ / s. After reaching the target temperature, hold for 10 s, and the billet will completely melt and shrink into bright spherical droplets.

[0070] (4) Turn off CO2 laser 3, and the droplet is rapidly cooled in the suspended gas flow at a rate of about 500 K / s to obtain a completely glassy CMAS microsphere.

[0071] like Figure 3 As shown in Figure A, the diameter of the CMAS microspheres is approximately 1.4 mm, which matches the target particle size, and the surface has a high degree of smoothness. Using the aforementioned method for calculating true sphericity, ImageJ software measured its true sphericity to be greater than 0.95, indicating a standard spherical shape.

[0072] (5) High temperature spreading application test: The CMAS microspheres prepared in this embodiment and the traditional irregular CMAS particles were placed vertically and gently on the center of the YSZ thermal barrier coating prepared by electron beam physical vapor deposition (EB-PVD), and then heated to 1250℃ on a micro testing platform for in-situ observation. Figure 4 This is a comparative diagram showing the two processes during high-temperature spreading. (For example...) Figure 4 As shown in A, traditional irregular particles have random initial contact points and irregular spreading fronts; while... Figure 4 As shown in B, the initial contact state of the CMAS microspheres in this embodiment is highly consistent (always single-point contact), followed by symmetrical collapse and uniform spreading. The spreading front is regular and smooth, verifying the superiority of this standard sample in providing deterministic boundary conditions.

[0073] Example 4: Preparation and Testing Application of Medium-Sized Glassy CMAS Microspheres

[0074] In this embodiment, glassy CMAS microspheres with a diameter of approximately 2.5 mm were prepared, and their spreadability was tested. The specific steps are as follows:

[0075] (1) Using natural volcanic ash as the raw powder for CMAS, approximately 25.0 mg of natural volcanic ash powder was weighed according to the density of natural volcanic ash. The powder was placed in a tableting mold and pressed into a cylindrical blank by applying a pressure of 100 MPa for 10 min.

[0076] (2) Place the billet above the nozzle of the sample stage 6 of the air suspension device, introduce high-purity oxygen, and control the flow rate to 1.2 L / min to make the billet suspend stably.

[0077] (3) Start CO2 laser 3 and heat the billet to 1900℃ continuously within 30 s at an average heating rate of about 63℃ / s. After reaching the target temperature, hold for 20 s, and the billet will completely melt and shrink into bright spherical droplets.

[0078] (4) Turn off CO2 laser 3, and the droplet is rapidly cooled in the suspended gas flow at a rate of about 500 K / s to obtain a completely glassy CMAS microsphere.

[0079] like Figure 3 As shown in Figure B, the diameter of the CMAS microspheres is approximately 2.3 mm, which matches the target particle size, and the surface has a high degree of smoothness. Using the aforementioned method for calculating true sphericity, ImageJ software measured its true sphericity to be greater than 0.95, indicating a standard spherical shape.

[0080] (5) High-temperature spreading application test: The CMAS microspheres prepared in this embodiment were placed vertically and gently on the center of the YSZ thermal barrier coating prepared by electron beam physical vapor deposition (EB-PVD). Then, the microspheres were heated to 1250℃ on the micro testing platform and observed in situ. It was observed that the initial contact state of the microspheres was highly consistent (always single-point contact), and then symmetrical collapse and uniform spreading occurred. The spreading front was regular and smooth, which verified the superiority of the standard sample in providing deterministic boundary conditions.

[0081] Example 5: Preparation and Testing Application of Large-Size Glassy CMAS Microspheres

[0082] In this embodiment, glassy CMAS microspheres with a diameter of approximately 3.0 mm were prepared, and their spreadability was tested. The specific steps are as follows:

[0083] (1) Using natural volcanic ash as the raw powder for CMAS, approximately 65.0 mg of natural volcanic ash powder was weighed based on the density of the natural volcanic ash. The powder was placed in a tableting mold and pressed into a cylindrical blank (e.g., ...) under a pressure of 100 MPa for 15 min. Figure 5 (As shown in B in the diagram).

[0084] (2) Place the billet above the nozzle of the sample stage 6 of the air suspension device, introduce high-purity oxygen, and control the flow rate to 1.2 L / min to make the billet suspend stably.

[0085] (3) Start the CO2 laser 3 and heat the billet to 2000℃ continuously within 35 s at an average heating rate of about 56℃ / s. After reaching the target temperature, hold for 30 s, and the billet will completely melt and shrink into bright spherical droplets.

[0086] (4) Turn off CO2 laser 3, and the droplet is rapidly cooled in the suspended gas flow at a rate of about 500 K / s to obtain a completely glassy CMAS microsphere.

[0087] like Figure 3 C and Figure 7 As shown in B, the diameter of the CMAS microspheres is approximately 3.01 mm, which matches the target particle size, and they have a high surface finish. Figure 8 As shown in B, using the aforementioned method for calculating true sphericity, the true sphericity measured by ImageJ software is greater than 0.95, reaching 0.96, which is the shape of a standard sphere.

[0088] (5) High-temperature spreading application test: The CMAS microspheres prepared in this embodiment were placed vertically and gently on the center of the YSZ thermal barrier coating prepared by electron beam physical vapor deposition (EB-PVD). Then, the microspheres were heated to 1250℃ on the micro testing platform and observed in situ. It was observed that the initial contact state of the microspheres was highly consistent (always single-point contact), and then symmetrical collapse and uniform spreading occurred. The spreading front was regular and smooth, which verified the superiority of the standard sample in providing deterministic boundary conditions.

[0089] Comparative Example 1: Large-sized (3.0 mm) CMAS microspheres were prepared using the preparation method provided by Chinese Patent CN119569313A.

[0090] (1) Select and weigh natural volcanic ash of the same batch and weight as in Example 5 as the original CMAS powder. Place the powder in a tableting mold, apply a high pressure of 400 MPa to press and shape it, and hold the pressure for 4 min to obtain the following: Figure 5 The cylindrical blank shown in Figure A.

[0091] (2) The blank was placed above the nozzle of the sample stage 6 of the air suspension device and prepared according to the method of Example 2 in the instruction manual CN119569313A. During the process, the operation mode of "heating-cooling-heating" was used to repeatedly perform 6 thermal cycles to force the removal of residual bubbles in the sample. Finally, CMAS microspheres with a particle size of 3.02 mm were prepared.

[0092] Testing and Comparative Analysis:

[0093] 1. Comparison of the microstructure of the blanks: The blanks formed by Example 5 and Comparative Example 1 were cut parallel to their surfaces, and the cross-sections were observed under an optical microscope. Figure 6 (The red circle indicates a recessed pit that is below the surface.) Figure 6 As shown in A in Comparative Example 1, the internal structure of the billet is compact, with small and isolated pores; as... Figure 6 As shown in B, the internal structure of the blank in Example 5 is relatively loose, with large and interconnected pores that form a network of exhaust channels.

[0094] 2. True Sphericity Comparison: Measured using ImageJ software, such as... Figure 7 and Figure 8 As shown in B, the CMAS microspheres prepared in Example 5 exhibit uniform surface tension distribution and a sphericity as high as 0.96, meeting the requirements of standardized experiments. And as... Figure 7 and Figure 8 As shown in A in the figure, the sphericity of the CMAS microspheres prepared in Comparative Example 1 is only 0.89.

[0095] 3. Comparison of ingredient fidelity: such as Figure 9 As shown, compared with the original natural volcanic ash, the CMAS microspheres prepared in Example 5 and Comparative Example 1 are similar in composition, but the composition deviation of Example 5 is smaller, indicating that its composition fidelity is higher.

[0096] The above results indicate that the applied pressure is the core parameter determining the permeability and venting effect of the green body. When the pressure exceeds 100 MPa, the green body becomes excessively dense, damaging the venting microporous structure and obstructing venting. This leads to increased process complexity (such as the need for repeated thermal shock) and decreased product quality (such as low sphericity and large compositional deviation). This invention strictly limits the applied pressure to the range of 10-100 MPa, preserving the venting channels while maintaining the strength of the green body. Internal gases can be expelled in a single, direct flow through flash heating, eliminating the need for complex thermal shock steps. The process is simple, energy-efficient, and yields a product with high sphericity and a composition closer to natural CMAS, meeting the requirements of subsequent standardized tests, such as CMAS spreading and wetting kinetics studies.

Claims

1. A method for preparing CMAS standard spheres based on gas dynamic pore synergy, characterized by, The steps include the following: S1, Calculate the required mass of CMAS raw powder based on the density of the raw CMAS powder and the particle size of the target CMAS standard spheres; S2, Weigh the original CMAS powder according to the required mass and place it in the tableting mold. Press it into a blank with a pressure of 10-100 MPa so that the interior of the blank forms a connected exhaust micropore structure. S3, the billet is placed in an air suspension device, and the billet is kept in a stable suspension state without contact by the flow of suspended gas. S4, using a laser heating device to heat the suspended billet, the billet is rapidly heated to 1800-2000℃ in one step within 20-40 seconds, so that the gas inside it is spontaneously discharged in one go through the exhaust micropore structure before the surface is completely liquefied and sealed. Then the billet is completely melted to form bubble-free spherical droplets. S5, turn off the laser heating device to allow the molten spherical droplets to cool and solidify rapidly in a suspended state, thereby obtaining CMAS standard spheres with the target particle size.

2. The preparation method according to claim 1, characterized in that, The original CMAS powder is selected from any one of the following: artificially synthesized CMAS powder, sand, volcanic ash, and dust.

3. The preparation method according to claim 1, characterized in that, When the particle size of the target CMAS standard sphere is less than 2 mm, the pressure applied to the pressed blank is 10-40 MPa and the holding time is 5-10 min; when the particle size of the target CMAS standard sphere is greater than or equal to 2 mm, the pressure applied to the pressed blank is 40-100 MPa and the holding time is 10-15 min.

4. The preparation method according to claim 1, characterized in that, The suspended gas is selected from any one of air, oxygen, nitrogen, or argon.

5. The preparation method according to claim 4, characterized in that, The suspended gas is oxygen.

6. The preparation method according to claim 1, characterized in that, The flow rate of the suspended gas is 0.8-1.5 L / min.

7. The preparation method according to claim 1, characterized in that, During the single-step flash heating process, the heating rate is 45-100℃ / s, and the holding time after reaching the target temperature is 10-30 s.

8. A CMAS standard sphere prepared by the preparation method according to any one of claims 1-7.

9. The CMAS standard sphere according to claim 8, characterized in that, The CMAS standard spheres are glassy spheres with a particle size of 1.0-3.5 mm and a sphericity ≥0.

95.

10. The application of the CMAS standard sphere as described in claim 8 or 9 in high-temperature spreading and / or wetting kinetics testing of thermal barrier coatings and / or environmental barrier coatings.

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