A multiphase composite spherical powder and a method for preparing the same

Abstract

The application relates to the technical field of high-temperature protective coating, in particular to a preparation method of a multiphase composite spherical powder, and the multiphase composite spherical powder is composed of SiC, Yb2SiO5 and SiBCN, and the mass ratio of the three phases is SiC:Yb2SiO5:SiBCN=(1-3):(1-3):1. The purpose of the preparation method of the multiphase composite spherical powder is to solve the problem that coating materials are difficult to simultaneously meet the comprehensive performance requirements of thermal matching, corrosion resistance, self-healing and microwave transmission.

Description

Technical Field

[0001] This invention relates to the field of high-temperature protective coating technology, specifically to a multiphase composite spherical powder and its preparation method. Background Technology

[0002] With the development of aerospace and high-speed aircraft, higher demands are placed on the corrosion resistance and structural stability of materials in high-temperature, high-humidity, and high-oxygen environments. Traditional single-phase or two-phase coating materials are prone to cracking, peeling, and corrosion at high temperatures, especially for ceramic matrix composites (such as SiC). f Coating systems with SiC (SiC) often fail at the interface due to mismatch in thermal expansion coefficients.

[0003] In existing technologies, commonly used high-temperature coating materials such as mullite, alumina, and yttrium silicates, while possessing certain temperature resistance, are prone to corrosion in high-temperature water and oxygen environments and lack self-healing capabilities. Furthermore, traditional coating materials often focus on single functions (such as heat insulation, wave absorption, and corrosion protection), making it difficult to achieve multi-functional integrated designs.

[0004] The shortcomings of existing methods mainly include: existing high-temperature resistant coating materials are prone to water and oxygen corrosion in high-temperature environments; they crack and peel off due to poor compatibility with the substrate; and they lack a self-healing mechanism, resulting in shortened coating life and reduced protective performance. Furthermore, existing methods for SiC... f Most coating material systems developed for SiC ceramic matrix composite substrates do not consider multifunctional composite design, making it difficult to simultaneously meet comprehensive performance requirements such as thermal matching, corrosion resistance, self-healing, and microwave permeability.

[0005] Therefore, the inventors provide a multiphase composite spherical powder and its preparation method. Summary of the Invention

[0006] (1) Technical problems to be solved This invention provides a multiphase composite spherical powder and its preparation method, which solves the technical problem that coating materials are difficult to simultaneously meet the comprehensive performance requirements of thermal matching, corrosion resistance, self-healing and microwave permeability.

[0007] (2) Technical solution This invention provides a multiphase composite spherical powder comprising SiC, Yb2SiO5 and SiBCN, with a three-phase mass ratio of SiC:Yb2SiO5:SiBCN = (1-3):(1-3):1.

[0008] This invention also provides a method for preparing multiphase composite spherical powder, comprising the following steps: Yb2SiO5 powder and SiBCN powder were mixed at a mass ratio of 1:1 to 3:1, deionized water and dispersant were added, and the mixture was ball-milled to obtain a uniform slurry. The slurry was spray-granulated to obtain Yb2SiO5 / SiBCN composite powder. The Yb2SiO5 / SiBCN composite powder and the polycarbosilane ceramic precursor were mixed at a mass ratio of 1:1 to 3:1 to form a uniform mixture. The mixture was subjected to high-temperature pyrolysis under an inert atmosphere to obtain pyrolysis products; The pyrolysis products were ball-milled to obtain multiphase composite spherical powder.

[0009] Furthermore, the particle size of the Yb2SiO5 powder is 0.5–5 μm.

[0010] Furthermore, the particle size of the SiBCN powder is 0.1–3 μm.

[0011] Furthermore, the polycarbosilane ceramic precursor is in a liquid or solid state.

[0012] Furthermore, the molecular weight of the polycarbosilane ceramic precursor is 800 to 3000.

[0013] Furthermore, the high-temperature pyrolysis temperature is 1200–1600℃.

[0014] Furthermore, the pyrolysis heating rate is 5–10 °C / min.

[0015] Furthermore, the particle size of the multiphase composite spherical powder is 10–80 μm.

[0016] Furthermore, the ball milling mixing time is 2–6 hours.

[0017] (3) Beneficial effects In summary, this invention utilizes SiC phase, SiBCN phase, and SiC... f / SiC ceramic matrix composites possess excellent thermal compatibility. By controlling the content of the three components and the particle size of the powder, multiphase composites can be achieved. Furthermore, a third type of SiC powder is introduced through precursor pyrolysis to ensure that the SiC phase, which plays a matching role, the Yb2SiO5 phase, which has a corrosion-resistant effect, and the SiBCN phase, which is a self-healing phase, can be homogeneously composited in the composite powder. After the three components are combined, the interface-controlled microwave function can be enhanced. The coating prepared by the material meets the comprehensive performance requirements of thermal compatibility, corrosion resistance, self-healing, and microwave permeability. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic flowchart of a method for preparing multiphase composite spherical powder according to an embodiment of the present invention; Figure 2 This is a SEM image of a SiC / Yb2SiO5 / SiBCN multiphase composite spherical powder provided in Embodiment 1 of the present invention. Detailed Implementation

[0020] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention, but should not be used to limit the scope of the present invention.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The first aspect of the present invention provides a multiphase composite spherical powder comprising SiC, Yb2SiO5 and SiBCN, wherein the mass ratio of the three phases is SiC:Yb2SiO5:SiBCN = (1-3):(1-3):1.

[0023] In the above embodiments, both the SiC and SiBCN phases in the powder exhibit good thermal compatibility with the SiCf / SiC ceramic matrix composite material. The prepared coating maintains good thermal compatibility with the SiCf / SiC ceramic matrix composite material substrate, eliminating the need for a transition layer to enhance compatibility and promoting lightweighting of the composite material. Simultaneously, the content of the three components and the particle size of the multiphase composite powder can be controlled to achieve multiphase composite formation. After three-phase composite formation, the microwave function can be controlled by adjusting the content and distribution of different powders at the interface, enabling regulation of microwave transmittance. The main principle is that the electromagnetic parameters of the composite powder can achieve low dielectric properties. Furthermore, the coating prepared using this powder meets comprehensive performance requirements such as thermal compatibility, corrosion resistance, self-healing (when cracks exist on the powder surface and oxygen can enter the powder interior, the SiBCN phase can generate B2O3 to fill the cracks, preventing further oxygen erosion), and microwave transmittance. Moreover, the spherical powder possesses good sphericity and flowability, making it suitable for processes such as plasma spraying and cold spraying.

[0024] A second aspect of this invention provides a method for preparing multiphase composite spherical powder, see below. Figure 1 The method may include the following steps: S100. Mix Yb2SiO5 powder and SiBCN powder at a mass ratio of 1:1 to 3:1, add deionized water and dispersant, and ball mill to obtain a uniform slurry.

[0025] Specifically, the particle size of Yb₂SiO₅ powder is 0.5–5 μm, and the particle size of SiBCN powder is 0.1–3 μm. This is mainly to consider the bonding between powders and subsequent processing requirements. Powders that are too large are difficult to distribute uniformly, while those that are too small tend to agglomerate and are difficult to mix. Ball milling is performed for 2–6 hours to obtain a uniform slurry. The purpose of using a mass ratio of 1:1 to 3:1 is to control the self-healing and corrosion-resistant functions of the powders, so as to optimize their overall performance. By adjusting the ratio of Yb₂SiO₅ to SiBCN, different corrosive environments can be adapted, and the final SiC phase content can be adjusted by changing the polycarbosilane content, allowing for flexible adjustment.

[0026] S200. Spray granulation of the slurry to obtain Yb2SiO5 / SiBCN composite powder.

[0027] S300: Mix Yb2SiO5 / SiBCN composite powder with polycarbosilane ceramic precursor at a mass ratio of 1:1 to 3:1 to form a uniform mixture.

[0028] Specifically, the purpose of using a mass ratio of 1:1 to 3:1 is to optimize the matching performance of the powder and its powder preparation process performance. Polycarbosilane is a liquid or solid ceramic precursor with a molecular weight of 800 to 3000. The main consideration is the process requirements for preparing powders through impregnation and pyrolysis. A molecular weight that is too large or too small will affect the uniformity of the prepared powder.

[0029] S400: The mixture is subjected to high-temperature pyrolysis under an inert atmosphere to obtain pyrolysis products.

[0030] Specifically, the inert atmosphere is argon or nitrogen, the pyrolysis heating rate is 5–10 °C / m, the pyrolysis temperature is 1200–1600 °C, and the holding time is 2–6 hours. A third type of SiC powder is introduced by pyrolysis of polycarbosilane precursors to ensure that the SiC phase, which plays a matching role, the Yb2SiO5 phase, which has a corrosion-resistant effect, and the SiBCN phase, which is a self-healing phase, can be homogeneously composited in the composite powder.

[0031] S500: The pyrolysis products are ball-milled to obtain multiphase composite spherical powder.

[0032] Specifically, the particle size of the multiphase composite spherical powder is 10 to 80 μm. The purpose of using this particle size is to meet the process requirements of the coating process. If the powder size is too large, it cannot meet the requirements of processes such as spraying.

[0033] Example 1 The preparation method of this multiphase composite spherical powder includes the following steps: (1) Mix Yb2SiO5 powder (particle size 1-3μm) and SiBCN powder (particle size 0.5-2μm) at a mass ratio of 1:1, add 1000g of deionized water and 20g of dispersant, and ball mill for 4 hours to obtain a uniform slurry; (2) The slurry was transferred to a spray drying tower, with the inlet temperature set at 250°C and the outlet temperature at 140°C, to obtain Yb2SiO5 / SiBCN composite powder; (3) Take the above composite powder and polycarbosilane (liquid, molecular weight 1500) and mix them at a mass ratio of 1:1 for 1 hour; (4) Place the mixture in an argon atmosphere furnace, heat it to 1400℃ at 8℃ / min, hold it for 4 hours, and carry out pyrolysis treatment; (5) The pyrolysis products were ball-milled and sieved to obtain SiC / Yb2SiO5 / SiBCN composite spherical powders with a particle size of 20-60 μm. The morphology of the powders is shown in the figure below. Figure 2 As shown.

[0034] Example 2 The preparation method of this multiphase composite spherical powder includes the following steps: (1) Mix Yb2SiO5 powder (particle size 0.5-2μm) and SiBCN powder (particle size 0.1-1μm) at a mass ratio of 3:1, add 500g of deionized water and 1.5g of polyvinyl alcohol dispersant, and ball mill for 3 hours to obtain a uniform slurry; (2) Transfer the slurry to a spray drying tower, set the inlet temperature to 280℃, the outlet temperature to 155℃, and the nozzle speed to 30Hz, and granulate to obtain Yb2SiO5 / SiBCN composite powder; (3) Take the above composite powder and solid polycarbosilane (molecular weight 2500) and mix them in a mixer at a mass ratio of 1:2 for 2 hours; (4) Place the mixture in a nitrogen atmosphere furnace, heat it to 1500℃ at 10℃ / min, hold it for 3 hours, and carry out pyrolysis; (5) The pyrolysis product was ball-milled in a planetary ball mill for 2 hours and then sieved to obtain SiC / Yb2SiO5 / SiBCN composite spherical powder with a particle size of 30-70 μm.

[0035] Example 3 The preparation method of this multiphase composite spherical powder includes the following steps: (1) Mix Yb2SiO5 powder (particle size 2-5μm) and SiBCN powder (particle size 1-3μm) at a mass ratio of 3:1, add 250g of deionized water and 2.5g of dispersant, and ball mill for 5 hours; (2) Transfer the slurry to the spray drying tower, set the inlet temperature to 240℃, the outlet temperature to 135℃, and the nozzle speed to 35Hz; (3) Take the composite powder and liquid polycarbosilane (molecular weight 1200) and mix them at a mass ratio of 1:1 for 1.5 hours; (4) The temperature was increased to 1300℃ at 5℃ / min under an argon atmosphere and held for 5 hours for pyrolysis; (5) After ball milling, the composite powder with a particle size of 15-50 μm was obtained by sieving.

[0036] It should be noted that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. Furthermore, for the sake of brevity, detailed descriptions of known methods and techniques are omitted here.

[0037] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art without departing from the scope of the invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.

Claims

1. A multiphase composite spherical powder, characterized in that, It consists of SiC, Yb2SiO5 and SiBCN, with a three-phase mass ratio of SiC:Yb2SiO5:SiBCN = (1~3):(1~3):

1.

2. A method for preparing multiphase composite spherical powder as described in claim 1, characterized in that, The method includes the following steps: Yb2SiO5 powder and SiBCN powder were mixed at a mass ratio of 1:1 to 3:1, deionized water and dispersant were added, and the mixture was ball-milled to obtain a uniform slurry. The slurry was spray-granulated to obtain Yb2SiO5 / SiBCN composite powder. The Yb2SiO5 / SiBCN composite powder and the polycarbosilane ceramic precursor were mixed at a mass ratio of 1:1 to 3:1 to form a uniform mixture. The mixture was subjected to high-temperature pyrolysis under an inert atmosphere to obtain pyrolysis products; The pyrolysis products were ball-milled to obtain multiphase composite spherical powder.

3. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The particle size of the Yb2SiO5 powder is 0.5–5 μm.

4. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The particle size of the SiBCN powder is 0.1–3 μm.

5. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The polycarbosilane ceramic precursor is either liquid or solid.

6. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The molecular weight of the polycarbosilane ceramic precursor is 800-3000.

7. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The high-temperature pyrolysis temperature is 1200–1600℃.

8. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The pyrolysis heating rate is 5–10 °C / min.

9. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The particle size of the multiphase composite spherical powder is 10–80 μm.

10. The method for preparing multiphase composite spherical powder according to claim 2, characterized in that, The ball milling mixing time is 2 to 6 hours.

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