Preparation method of SiC fiber reinforced BeO crucible

Abstract

The invention discloses a preparation method of a SiC fiber reinforced BeO crucible, which is used for solving the problem that the toughness, thermal shock resistance and compactness of the existing BeO crucible cannot be considered at the same time, and the preparation method comprises the following steps: respectively pretreating SiC fiber and BeO powder; mixing and ball-milling the pretreated SiC fibers, BeO powder, a dispersant, a binder, a plasticizer and a sintering aid in a solvent to obtain mixed slurry, and granulating the mixed slurry to obtain a mixture; performing cold isostatic pressing on the mixture to obtain a green body; and carrying out heat treatment strengthening on the green body to obtain the SiC fiber reinforced BeO crucible. The SiC fiber reinforced BeO crucible prepared by the method disclosed by the invention is high in density, high in toughness and excellent in thermal shock resistance.

Description

Technical Field

[0001] This invention relates to the field of beryllium oxide crucible preparation technology, and in particular to a method for preparing a SiC fiber reinforced BeO crucible. Background Technology

[0002] BeO possesses properties such as a high melting point, good thermal conductivity, excellent chemical stability, and a low coefficient of thermal expansion, demonstrating enormous application potential in high-temperature industries, electronics, and aerospace. Especially in processes requiring extreme temperature environments, such as high-temperature melting and crystal growth, BeO crucibles are a highly attractive container material. However, pure BeO crucibles have some inherent drawbacks: they are relatively brittle, have poor thermal shock resistance, and are prone to cracking under rapid temperature changes, which significantly limits their service life and application range. Therefore, developing a BeO crucible preparation method that improves the crucible's toughness, thermal shock resistance, and mechanical strength has become a key technical challenge urgently needing to be solved in this field. Summary of the Invention

[0003] In view of the above, the present invention aims to provide a method for preparing SiC fiber reinforced BeO crucibles to at least solve one of the following technical problems: the toughness, thermal shock resistance and density of existing BeO crucibles cannot be simultaneously achieved.

[0004] The objective of this invention is mainly achieved through the following technical solutions:

[0005] This invention provides a method for preparing a SiC fiber-reinforced BeO crucible, comprising the following steps:

[0006] Step 1: Pre-treat SiC fibers and BeO powder separately;

[0007] Step 2: Mix the pretreated SiC fibers with the pretreated BeO powder, dispersant, binder, plasticizer, and sintering aid in a solvent and ball mill to obtain a mixed slurry. Then, granulate the mixed slurry to obtain a mixture.

[0008] Step 3: The mixture is subjected to cold isostatic pressing to obtain a green body;

[0009] Step 4: Heat-treat the green body to strengthen it, and obtain a SiC fiber reinforced BeO crucible.

[0010] Furthermore, in step 1, the pretreatment of SiC fibers includes the following steps: cleaning the surface of the SiC fibers, and then coating the surface of the SiC fibers with a pyrolytic carbon interface layer or a BN interface layer using a chemical vapor deposition method.

[0011] Furthermore, in step 1, the pretreatment of BeO powder includes the following steps: placing BeO powder in a container, then placing the container in a heating furnace, heating it to 600-800°C in an air atmosphere, holding it at that temperature, and then cooling it to room temperature with the furnace.

[0012] Furthermore, in step 2, the dispersant is polyphosphate, the binder is polyvinyl butyral, the plasticizer is dibutyl phthalate, the sintering aid is Al2O3-Y2O3, and the solvent is ethanol.

[0013] Furthermore, in step 2, the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer, and sintering aid is 100:9-11:100:0.5-1.5:5-9:20-40:1-3.

[0014] Furthermore, in step 2, the dispersant and solvent are first mixed, then BeO powder and sintering aid are added to the above solution and ball-milled for 1-2 hours. Finally, the binder and plasticizer are added, and the mixture is ball-milled for 3.5-4.5 hours. Then, SiC fibers are sprinkled into the slurry under stirring and ball-milled again.

[0015] Furthermore, in step 3, the pressure of the cold isostatic pressing is 200-300 MPa, and the holding time is 5-8 min.

[0016] Furthermore, the thickness of the interface layer is 100–500 nm.

[0017] Furthermore, in step 4, the heat treatment strengthening includes the following steps:

[0018] S401. Place the green billet into the sintering furnace, close the furnace door, and evacuate to a vacuum of 5×10⁻⁶. -3 Once the temperature drops below Pa, begin heating and maintain the temperature at 580–600°C.

[0019] S402, continue heating to 1700-1800℃ and then hold at that temperature;

[0020] S403, after furnace cooling, yields a SiC fiber-reinforced BeO crucible.

[0021] The present invention also provides a SiC fiber reinforced BeO crucible, which is prepared by the above-described preparation method.

[0022] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0023] The preparation method of this invention effectively improves the interfacial bonding performance between BeO powder and SiC fibers through pretreatment, laying the foundation for the preparation of high-performance crucibles. The use of cold isostatic pressing allows for precise control of the crucible's shape and size, while ensuring high material density and a uniform microstructure. The addition of SiC fibers significantly improves the crucible's strength and toughness, making it less prone to breakage under high temperatures and external impacts, thus extending its service life. Simultaneously, the presence of fibers improves the crucible's thermal conductivity and thermal expansion properties, enabling it to better adapt to thermal cycling changes under high-temperature environments, reducing thermal stress damage, and improving the crucible's thermal shock resistance.

[0024] The preparation method of the present invention ensures uniform fiber dispersion, reduces the probability of sintering cracks, and improves crucible density by precisely controlling each process step and process parameter.

[0025] The preparation method of the present invention has strong process controllability, good product consistency, and is suitable for large-scale production.

[0026] The SiC fiber-reinforced BeO crucible of the present invention exhibits high density, high toughness, and excellent thermal shock resistance. For example, the density is above 87%, such as 87%–92%; the toughness is 4.5 MPa·m. 1 / 2 The above, for example, 4.5–6 MPa·m 1 / 2 It can withstand ≥10 heat cycles at 1600℃.

[0027] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of what is particularly pointed out in the written description. Detailed Implementation

[0028] Preferred embodiments of the present invention are described in detail below.

[0029] This invention provides a method for preparing a SiC fiber-reinforced BeO crucible, comprising the following steps:

[0030] Step 1: Pre-treat SiC fibers and BeO powder separately;

[0031] Step 2: Mix the pretreated SiC fibers with the pretreated BeO powder, dispersant, binder, plasticizer, and sintering aid in a solvent and ball mill to obtain a mixed slurry. Then, granulate the mixed slurry to obtain a mixture.

[0032] Step 3: The mixture is subjected to cold isostatic pressing to obtain a green body with uniform fiber distribution and high density;

[0033] Step 4: Heat-treat the green body to strengthen it, and obtain a SiC fiber reinforced BeO crucible.

[0034] Specifically, in step 1 above, considering the surface activity of BeO powder, the BeO powder is pretreated. The pretreatment of BeO powder includes the following steps: placing the BeO powder in a beryllium oxide ceramic crucible, then placing the crucible in a muffle furnace, heating it to 600-800℃ at a rate of 2-5℃ / min in air atmosphere, holding it at that temperature for 1-2 hours, and then allowing the powder to cool naturally to room temperature with the furnace. The pretreated BeO powder possesses the characteristics of high purity, controllable surface state, and stable sintering activity, which lays a solid foundation for subsequent uniform slurry preparation, high-density molding, and repeatable sintering densification.

[0035] Specifically, in step 1 above, the pretreatment of SiC fibers includes the following steps:

[0036] The SiC fiber is cleaned, and then a pyrolytic carbon interface layer (PyC) or BN interface layer with a thickness of about 100-500 nm is uniformly coated on the surface of the SiC fiber using chemical vapor deposition (CVD).

[0037] Specifically, in step 1 above, the PyC or BN interface layer can both suppress interfacial reactions and serve as a stress relaxation layer. Considering that excessive layer thickness would lead to large-scale debonding at the interface and premature crack deflection, while insufficient thickness would prevent the formation of a complete and continuous weak interface layer, the thickness of the interface layer is controlled to be 100–500 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, or 500 nm.

[0038] It should be noted that, during the pretreatment of SiC fibers, in order to prevent uneven coating, fluidized bed CVD or uniform movement of the SiC fiber bundles within the furnace is employed. Preferably, the uniform movement speed of the SiC fiber bundles within the furnace is 1.0–5.0 cm / min, for example, 1.0 cm / min, 2.0 cm / min, 3.0 cm / min, 4.0 cm / min, or 5.0 cm / min.

[0039] Specifically, in step 1 above, during the SiC fiber pretreatment process, if the deposition temperature is too high, the fiber may crystallize or grow grains, resulting in a decrease in the fiber's strength; if the deposition temperature is too low, the coating will contain a large number of pores and impurities, leading to weak adhesion. Therefore, the deposition temperature is controlled at 890–910℃, for example, 890℃, 900℃, or 910℃.

[0040] Specifically, in step 1 above, the surface modification of BeO powder and SiC fiber through pretreatment effectively improves the interfacial bonding performance between BeO powder and SiC fiber, laying the foundation for the preparation of high-performance crucibles.

[0041] Specifically, in step 2 above, the dispersant is polyphosphate (KD-4), the binder is polyvinyl butyral (PVB-45), the plasticizer is dibutyl phthalate (DBP), the sintering aid is Al2O3-Y2O3, and the solvent is ethanol.

[0042] Specifically, in step 2 above, considering that excessive SiC fiber usage can lead to uneven interfacial bonding and premature failure, or insufficient matrix to provide enough frictional resistance, shortening the pull-out process and reducing energy consumption; insufficient fiber quantity cannot effectively "bridge" and "pull out" to consume energy. Cracks will directly penetrate the entire material, manifesting as brittle fracture, with almost no fiber pull-out. Excessive dispersant usage will lead to poor slurry rheology, excessively high organic content after drying, difficulty in debinding, and easy cracking; insufficient dispersant usage will lead to uneven slurry, low and uneven green body density, abnormal grain growth after sintering, and low strength. Excessive binder usage will lead to excessive organic matter decomposition, easily causing green body cracking, bubbling, and delamination; insufficient binder usage will lead to low green body yield and many edge defects. Excessive plasticizer usage will lead to excessive softening of the binder network, making the green body easy to deform and possibly sticking to the mold; insufficient plasticizer usage will lead to poor flexibility, weak bending resistance, and slight deformation. Excessive use of sintering aids can severely degrade high-temperature performance and reduce corrosion resistance, while insufficient use can lead to porous green bodies with substandard density and strength, resulting in poor performance. Excessive use of solvents can lead to low solid content, causing powder sedimentation and uneven composition between layers, while insufficient use can lead to high solid content, difficulty in removing air bubbles, poor leveling, difficulty filling the mold, and numerous green body defects. Therefore, the mass ratio of pretreated BeO powder (hereinafter referred to as BeO powder for convenience), pretreated SiC fibers (hereinafter referred to as SiC fibers for convenience), ethanol solvent, dispersant, binder, plasticizer, and sintering aids should be controlled at 100:9~11:100:0.5~1.5:5~9:20~40:1~3.

[0043] Preferably, the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer, and sintering aid is 100:9-11:100:0.5-1.2:5-8:20-30:1-2.

[0044] Specifically, in step 2 above, the dispersant is first mixed with the ethanol solvent, then the BeO powder and sintering aid are added to the solution and ball-milled for 1 to 2 hours. Finally, the binder and plasticizer are added and ball-milled for 3.5 to 4.5 hours. Then, the SiC fiber is gradually and evenly sprinkled into the slurry under stirring, and ball-milled for another 0.8 to 1.2 hours.

[0045] Specifically, in step 2 above, ultrasonic dispersion is used to assist in the material mixing process.

[0046] Specifically, in step 2 above, excessively long ultrasonic time may cause fiber breakage, decrease the aspect ratio, and affect the toughening effect. Therefore, the ultrasonic time after SiC fiber is sprinkled into the slurry should be controlled to be 25-35 minutes.

[0047] Specifically, in step 2 above, excessively high ball milling speed or excessively long milling time can easily lead to fiber breakage and the introduction of impurities, while excessively low speed or excessively short milling time can cause fiber and powder agglomeration. Therefore, the ball milling speed after adding SiC fibers should be controlled at 250–300 rpm (e.g., 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm, 300 rpm) and the time at 0.8–1.2 h to ensure uniform dispersion of SiC fibers.

[0048] Specifically, in step 2 above, the granulation parameters are: 1.9~3.1MPa, inlet air temperature 190~210℃, outlet air temperature 100~110℃, and solid content 43%~47%.

[0049] Specifically, in step 2 above, the particle size distribution of the mixture is as follows:

[0050] The mass percentage of coarse particles with a diameter of >5 to 10 μm (excluding 5 μm) is 18% to 30%.

[0051] The proportion of medium particles with a diameter of >2 to 5 μm (excluding 2 μm) is 55% to 58%.

[0052] Fine particles of 0.5–2 μm account for 15%–25% of the total mass.

[0053] It should be noted that the purpose of controlling the above particle size distribution is to achieve high density in green body, low shrinkage during sintering, and ultimately high density. Coarse particles of >5-10μm form the basic framework of the green body, providing macroscopic strength and stability, reducing the overall specific surface area, and thus reducing the sintering driving force requirement and shrinkage rate. If the proportion is too high, the overall density of the product is low, and isolated large pores exist. During the heat treatment stage, coarse particles will grow engulfed due to grain boundary energy differences, resulting in uneven grain size and the appearance of abnormally large coarse grains in some areas. If the proportion of coarse particles is too low, the framework effect is weakened, and the green body is more likely to break due to insufficient strength during demolding and handling. At the same time, due to the lack of support from large particles, the proportion of fine particles increases relatively, which may lead to excessive slurry viscosity and poor processability. Furthermore, the relatively increased proportion of highly active fine particles leads to violent material transport during sintering, resulting in a significant increase in linear shrinkage and total shrinkage, which can easily cause deformation, warping, or even cracking of the green body. Too many fine particles will cause the densification rate to be too fast in the early stage of sintering, and the surface to densify too early, trapping gas inside the green body to form closed pores that are difficult to expel during subsequent heat treatment, thus reducing the final density. Taking all factors into consideration, the quality percentage should be controlled between 18% and 30%, for example, 18%, 20%, 22%, 24%, 26%, 28%, and 30%.

[0054] Medium-sized particles (>2–5 μm) form the main body and bridge of the system, and are the most numerous. They primarily fill the larger gaps between coarse particles and provide an adhesion matrix for fine particles. During sintering, medium-sized particles are the main channels and participants for mass transport (from fine particles to coarse particles, or through diffusion across grain boundaries). To ensure the continuity, homogeneity, and sufficient sintering activity of the system, the proportion of medium-sized particles is controlled at 55%–58%, for example, 55%, 56%, 57%, and 58%.

[0055] Fine particles of 0.5–2 μm possess high specific surface area and surface energy, acting as activators and driving forces in the sintering process. During cold pressing, fine particles lubricate coarse and medium-sized particles, promoting sliding rearrangement. During sintering, fine particles preferentially dissolve or migrate, rapidly filling residual micropores and significantly promoting densification. Excessive fine particles drastically increase the total specific surface area of ​​the powder, requiring more citric acid solution for wetting, making the slurry highly viscous or even pasty, hindering ball milling and resulting in extremely poor slurry flowability. The extremely high surface energy of fine particles leads to excessive sintering activity during heat treatment, causing excessively rapid grain boundary migration and rapid grain merging and growth at lower temperatures, easily resulting in grain coarsening and potential internal stress due to inconsistent sintering rates, leading to unstable performance. Insufficient fine particles result in insufficient sintering driving force, preventing adequate densification at low temperatures and resulting in high porosity. Considering all factors, the mass percentage of fine particles of 0.5–2 μm should be controlled at 15%–25%, for example, 15%, 20%, or 25%.

[0056] Specifically, in step 3 above, excessive pressure during cold isostatic pressing leads to fiber breakage and powder fragmentation, while insufficient pressure results in excessively low product density. Therefore, the pressure during cold isostatic pressing should be controlled between 200 and 300 MPa, for example, 200 MPa, 220 MPa, 240 MPa, 250 MPa, 270 MPa, or 300 MPa.

[0057] Specifically, in step 3 above, an excessively long holding time during cold isostatic pressing increases the risk of fiber breakage, while an excessively short holding time can lead to dimensional expansion of the preform, microcracks, or even macroscopic delamination. Therefore, the holding time during cold isostatic pressing should be controlled to be 5–8 minutes, for example, 5 minutes, 6 minutes, 7 minutes, or 8 minutes.

[0058] Specifically, in step 4 above, considering that SiC fibers hinder BeO grain boundary migration and that the large difference in thermal expansion coefficients between SiC fibers and the matrix can easily lead to sintering cracks, heat treatment strengthening requires segmented temperature control.

[0059] Specifically, in step 4 above, heat treatment strengthening includes the following steps:

[0060] S401. Place the green billet into the sintering furnace, close the furnace door, and evacuate to a vacuum of 5×10⁻⁶. -3 Once the temperature drops below Pa, begin heating and maintain the temperature at 580–600°C.

[0061] S402, continue heating to 1700-1800℃ and then hold at that temperature;

[0062] S403, after furnace cooling, yields a SiC fiber-reinforced BeO crucible.

[0063] Specifically, the function of S401 is to remove organic binders and residual solvents. If the heating rate is too high, the gas inside the blank cannot be discharged in time, resulting in local expansion, forming bubbles or macroscopic swelling. If the heating rate is too low, the organic matter may undergo unfavorable slow carbonization instead of complete decomposition and volatilization, which will increase the risk of residual carbon. Therefore, the heating rate is controlled at 1 to 2℃ / min, such as 1℃ / min, 1.5℃ / min, or 2℃ / min.

[0064] Specifically, in S401 above, excessively high insulation temperatures may cause early oxidation or unfavorable changes in grain structure, leading to a decrease in the original strength of the fiber; excessively low insulation temperatures may result in some polymer chains or carbonaceous residues not being removed; excessively long insulation times will increase energy consumption, while excessively short insulation times will result in incomplete removal of organic solvents. Therefore, the insulation temperature should be controlled at 580–600℃, for example, 580℃, 590℃, or 600℃; and the insulation time should be 1.5–2.5h, for example, 1.5h, 2h, or 2.5h.

[0065] Specifically, the function of S402 is to promote the diffusion, rearrangement, and densification of BeO grains, forming a SiC fiber-reinforced BeO crucible. Too rapid a heating rate will generate enormous thermal stress, leading to cracking of the billet; too slow a rate results in extremely low production efficiency and high energy consumption. Therefore, the heating rate should be controlled at 4–5 °C / min, for example, 4 °C / min, 4.5 °C / min, or 5 °C / min. If the holding temperature is too high, SiC reacts with BeO: 2BeO + SiC → 2Be + SiO↑ + CO↑, generating gaseous SiO / CO products, causing internal porosity and weakening density. If the holding time is too long, the grains grow excessively; if the holding time is too short, the billet will not densify sufficiently. Therefore, the insulation temperature should be controlled at 1700-1800℃, for example, 1700℃, 1720℃, 1750℃, 1770℃, 1800℃; and the insulation time should be 1.5-2h, for example, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, 2h.

[0066] Specifically, in S401 and S402 above, the vacuum atmosphere is controlled, for example, the vacuum level is 5×10⁻⁶. -3 Below Pa.

[0067] Specifically, the SiC fiber reinforced BeO crucible obtained in step 4 above has high density, high toughness, and excellent thermal shock resistance.

[0068] The preparation method of this invention effectively improves the interfacial bonding performance between BeO powder and SiC fibers through pretreatment, laying the foundation for the preparation of high-performance crucibles. The use of cold isostatic pressing allows for precise control of the crucible's shape and size, while ensuring high material density and a uniform microstructure. The addition of SiC fibers significantly improves the crucible's strength and toughness, making it less prone to breakage under high temperatures and external impacts, thus extending its service life. Simultaneously, the presence of fibers improves the crucible's thermal conductivity and thermal expansion properties, enabling it to better adapt to thermal cycling changes under high-temperature environments, reducing thermal stress damage, and improving the crucible's thermal shock resistance.

[0069] The preparation method of the present invention ensures uniform fiber dispersion, reduces the probability of sintering cracks, and improves crucible density by precisely controlling each process step and process parameter.

[0070] The preparation method of the present invention has strong process controllability, good product consistency, and is suitable for large-scale production.

[0071] The SiC fiber-reinforced BeO crucible of the present invention exhibits high density, high toughness, and excellent thermal shock resistance. For example, the density is above 87%, such as 87%–92%; the toughness is 4.5 MPa·m. 1 / 2 The above, for example, 4.5–6 MPa·m 1 / 2It can withstand ≥10 heat cycles at 1600℃.

[0072] The advantages of the method of the present invention will be demonstrated below with specific embodiments and comparative examples.

[0073] Example 1

[0074] This embodiment provides a method for preparing a SiC fiber reinforced BeO crucible, including the following steps:

[0075] (1) The SiC fiber is cleaned, and then a BN interface layer of about 200 nm thick is uniformly coated on the surface of the SiC fiber by chemical vapor deposition. During the chemical vapor deposition process, the SiC fiber bundle is moved at a constant speed in the furnace at a speed of 1.0 cm / min and a deposition temperature of 900 °C.

[0076] The pretreatment of BeO powder includes: placing BeO powder in a beryllium oxide ceramic crucible, then placing the crucible in a muffle furnace, heating it to 700°C at a rate of 3°C / min in an air atmosphere, and holding it at this temperature for 1.5 hours. After the holding period, the heating program is turned off, and the powder is allowed to cool naturally to room temperature with the furnace, thus completing the pretreatment of the powder.

[0077] (2) Weigh the materials according to the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer, and sintering aid of 100:10:100:1:6:20:2. First, mix the dispersant with the ethanol solvent, then add the BeO powder and sintering aid to the above solution and ball mill for 1 hour. Then add the binder and plasticizer and ball mill for 3.5 hours. Under stirring, gradually and evenly sprinkle the SiC fiber into the slurry and ball mill for another 1 hour at a speed of 250 rpm to obtain a mixed slurry. Then granulate the slurry with the following parameters: pressure: 2.0 MPa, inlet air temperature: 200℃, outlet air temperature: 105℃, and solid content: 45%.

[0078] In the process of material mixing, ultrasonic dispersion is used to assist in the process. After the SiC fiber is sprinkled into the slurry, the ultrasonic time is 25 minutes.

[0079] The particle size distribution of the mixture is as follows:

[0080] Coarse particles (>5–10 μm) account for approximately 20% of the total mass; medium particles (>2–5 μm) account for approximately 56% of the total mass; and fine particles (0.5–2 μm) account for approximately 24% of the total mass.

[0081] (3) Then the mixture is placed in the mold and formed by cold isostatic pressing at 200MPa for 8 minutes to obtain the green body;

[0082] (4) Remove the formed green blank and place it in the sintering furnace for heat treatment. After closing the furnace door, evacuate the vacuum to 5×10⁻⁶. -3 After Pa, heating begins. The first stage involves heating to 600℃ (heating rate 2℃ / min, holding for 2h, under vacuum atmosphere), and the second stage involves heating to 1750℃ (heating rate 5℃ / min, holding for 2h, under vacuum atmosphere). After cooling, the crucible is removed and, after fine processing, a SiC fiber-reinforced BeO crucible is obtained.

[0083] The crucible in this embodiment has a density of 92% and a toughness of 4.5 MPa·m. 1 / 2 It can withstand ≥12 heat cycles at 1600℃.

[0084] Example 2

[0085] This embodiment provides a method for preparing a SiC fiber reinforced BeO crucible. The preparation method in this embodiment is generally the same as that in Embodiment 1, except that:

[0086] (2) The materials were weighed according to the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer and sintering aid of 100:9:100:0.7:5:21:1. The dispersant and ethanol solvent were mixed first, and then the BeO powder and sintering aid were added to the above solution and ball-milled for 1.5h. Finally, the binder and plasticizer were added and ball-milled for 4h. Then, the SiC fiber was gradually and evenly sprinkled into the slurry under stirring, and ball-milled for another 1h at a speed of 260rpm. The mixed slurry was obtained and then granulated.

[0087] The particle size distribution of the mixture is as follows:

[0088] Coarse particles (>5–10 μm) account for approximately 23% of the total mass; medium particles (>2–5 μm) account for approximately 55% of the total mass; and fine particles (0.5–2 μm) account for approximately 22% of the total mass.

[0089] (3) In the process, cold isostatic pressing is performed at 230MPa for 7 minutes;

[0090] The remaining steps and process parameters are the same as in Example 1.

[0091] The crucible in this embodiment has a density of 90% and a toughness of 6 MPa·m. 1 / 2 It can withstand ≥20 heat cycles at 1600℃.

[0092] Example 3

[0093] This embodiment provides a method for preparing a SiC fiber reinforced BeO crucible. The preparation method in this embodiment is generally the same as that in Embodiment 1, except that:

[0094] In (2), the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer, and sintering aid is 100:11:100:1.2:7:25:1;

[0095] (3) In the process, cold isostatic pressing is performed at 300MPa for 5 minutes;

[0096] In (4), the first stage is heated to 580℃ (heating rate 2℃ / min, holding for 2h, vacuum atmosphere), the second stage is heated to 1770℃ (heating rate 5℃ / min, holding for 1.8h, vacuum atmosphere), and the crucible is removed after cooling.

[0097] The crucible in this embodiment has a density of 87% and a toughness of 5.4 MPa·m. 1 / 2 It can withstand ≥10 heat cycles at 1600℃.

[0098] The inventors conducted extensive research during the research process, and some suboptimal solutions are presented here as comparative examples.

[0099] Comparative Example 1

[0100] This comparative example provides a method for preparing a beryllium oxide crucible. In this comparative example, SiC fibers are not added, and the remaining steps are the same as in Example 1.

[0101] The crucible in this comparative example has a density of 91% and a toughness of 2.7 MPa·m. 1 / 2 The thermal shock resistance is ≥5 cycles. In this comparative example, because no fibers were added, the beryllium oxide crucible lacks a core mechanism to resist crack propagation induced by thermal stress, resulting in poor thermal shock resistance.

[0102] Comparative Example 2

[0103] This comparative example provides a method for preparing a beryllium oxide crucible, including the following steps:

[0104] In (1), SiC fibers and BeO powder are not pretreated and are directly carried out in steps (2)-(4).

[0105] The crucible in this comparative example has a density of 89% and a toughness of 3.8 MPa·m. 1 / 2 The thermal shock resistance is ≥8 cycles. In this comparative example, because there is no dedicated coating for CVD deposition to construct a "controllable weak interface", the fiber and the matrix are connected. Under thermal shock, the stress cannot be released and the cracks cannot be deflected, resulting in poor thermal shock resistance of the crucible.

[0106] Comparative Example 3

[0107] This comparative example provides a method for preparing a beryllium oxide crucible, including the following steps:

[0108] (1) of this comparative example is the same as that of Example 1, and will not be repeated here;

[0109] In (2), the particle size distribution does not meet the requirements:

[0110] Particles with a size of >5 to 10 μm account for approximately 40% of the total mass.

[0111] Particles with a size of >2 to 5 μm account for approximately 45% of the total mass.

[0112] Particles ranging from 0.5 to 2 μm account for approximately 15% of the total mass.

[0113] The crucible in this comparative example has a density of 87% and a toughness of 4.1 MPa·m. 1 / 2 The thermal shock resistance is ≥6 cycles. The comparative example has an excessive proportion of coarse particles, resulting in lower overall crucible performance compared to the example.

[0114] Comparative Example 4

[0115] This comparative example provides a method for preparing a beryllium oxide crucible, including the following steps:

[0116] (1) of this comparative example is the same as that of Example 1, and will not be repeated here.

[0117] (4) In this step, the green billet is placed in the sintering furnace, the furnace door is closed, and a vacuum of 5×10 is drawn. -3 Heating begins once the temperature drops below Pa, and the temperature is directly raised to 1750℃ before being held at that temperature.

[0118] The crucible in this comparative example has a density of 85% and a toughness of 2.0 MPa·m. 1 / 2 Thermal shock resistance ≥3 cycles. Directly heating to 1750℃ and holding at that temperature causes the organic matter inside the blank to decompose and vaporize rapidly. The large amount of gas produced cannot be discharged in time, thus forming defects inside the material and affecting the performance of the crucible.

[0119] Comparative Example 5

[0120] This comparative example provides a method for preparing a beryllium oxide crucible, including the following steps:

[0121] (1) of this comparative example is the same as that of Example 1, and will not be repeated here.

[0122] In (2), the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer and sintering aid is 100:20:100:5:5:20:10. The remaining steps are the same as in Example 1, and will not be repeated here.

[0123] The crucible in this comparative example has a density of 86% and a toughness of 2.7 MPa·m. 1 / 2Thermal shock resistance ≥ 4 cycles. Excessive fiber can disrupt matrix continuity and introduce agglomeration defects; excessive dispersant can leave impurities and weaken the interface; excessive sintering aids can form brittle intergranular phases, which become the preferred path for thermal stress cracking.

[0124] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a SiC fiber-reinforced BeO crucible, characterized in that, The preparation method includes the following steps: Step 1: Pre-treat SiC fibers and BeO powder separately; Step 2: Mix the pretreated SiC fibers with the pretreated BeO powder, dispersant, binder, plasticizer, and sintering aid in a solvent and ball mill to obtain a mixed slurry. Then, granulate the mixed slurry to obtain a mixture. Step 3: The mixture is subjected to cold isostatic pressing to obtain a green body; Step 4: Heat-treat the green body to strengthen it, and obtain a SiC fiber reinforced BeO crucible.

2. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 1, characterized in that, In step 1, the pretreatment of SiC fibers includes the following steps: cleaning the surface of the SiC fibers, and then coating the surface of the SiC fibers with a pyrolytic carbon interface layer or a BN interface layer using a chemical vapor deposition method.

3. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 1, characterized in that, In step 1, the pretreatment of BeO powder includes the following steps: placing BeO powder in a container, then placing the container in a heating furnace, heating it to 600-800°C in an air atmosphere, holding it at that temperature, and then cooling it to room temperature with the furnace.

4. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 1, characterized in that, In step 2, the dispersant is polyphosphate, the binder is polyvinyl butyral, the plasticizer is dibutyl phthalate, the sintering aid is Al2O3-Y2O3, and the solvent is ethanol.

5. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 4, characterized in that, In step 2, the mass ratio of BeO powder, SiC fiber, ethanol solvent, dispersant, binder, plasticizer, and sintering aid is 100:9-11:100:0.5-1.5:5-9:20-40:1-3.

6. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 1, characterized in that, In step 2, the dispersant and solvent are mixed first, then BeO powder and sintering aid are added to the above solution and ball-milled for 1-2 hours. Finally, the binder and plasticizer are added and ball-milled for 3.5-4.5 hours. Then, SiC fibers are sprinkled into the slurry under stirring and ball-milled again.

7. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 1, characterized in that, In step 3, the pressure of cold isostatic pressing is 200-300 MPa, and the holding time is 5-8 min.

8. The method for preparing the SiC fiber-reinforced BeO crucible according to claim 2, characterized in that, The thickness of the interface layer is 100–500 nm.

9. The method for preparing a SiC fiber-reinforced BeO crucible according to any one of claims 1 to 8, characterized in that, Step 4, heat treatment strengthening, includes the following steps: S401. Place the green billet into the sintering furnace, close the furnace door, and evacuate to a vacuum of 5×10⁻⁶. -3 Once the temperature drops below Pa, begin heating and maintain the temperature at 580–600°C. S402, continue heating to 1700-1800℃ and then hold at that temperature; S403, after furnace cooling, yields a SiC fiber-reinforced BeO crucible.

10. A SiC fiber-reinforced BeO crucible, characterized in that, The SiC fiber reinforced BeO crucible is prepared using the preparation method described in any one of claims 1 to 9.