Pyrolytic boron nitride crucible resistant to infiltration corrosion of molten aluminum and preparation method of pyrolytic boron nitride crucible

Abstract

The invention relates to the technical field of pyrolytic boron nitride crucibles, in particular to a pyrolytic boron nitride crucible resistant to molten aluminum infiltration corrosion and a preparation method of the pyrolytic boron nitride crucible, and is suitable for molecular beam epitaxy aluminum plating crucibles. The pyrolytic boron nitride crucible is composed of the pyrolytic boron nitride crucible body and the molten aluminum infiltration corrosion resistant coating coated on the surface of the pyrolytic boron nitride crucible body, the aluminum nitride coating can effectively isolate and protect pyrolytic boron nitride from molten aluminum, and the undesirable phenomena that the molten aluminum infiltrates the crucible and overflows, the crucible is corroded, the service life of the crucible is shortened, the molten aluminum is polluted and the like can be greatly avoided. Therefore, the molecular beam stability can be effectively controlled and the quality of epitaxial products can be improved. The preparation method of the pyrolytic boron nitride crucible comprises the steps that the pyrolytic boron nitride crucible body is prepared, the surface of the pyrolytic boron nitride crucible body is subjected to roughening treatment, and the aluminum nitride coating is coated, and according to the method, good matching and firm combination of the pyrolytic boron nitride crucible body and the aluminum nitride coating are achieved through a chemical vapor deposition method and a rough interface mechanism; therefore, the long-life infiltration corrosion resistance is realized.

Description

Technical Field

[0001] This invention relates to the field of pyrolytic boron nitride crucible technology, specifically to a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion and its preparation method, applicable to molecular beam epitaxy aluminum plating crucibles. Background Technology

[0002] Pyrolytic boron nitride (PBN), prepared by chemical vapor deposition, is widely used as a crucible for high-temperature melting and evaporation of high-purity raw materials due to its high purity, dense and non-porous surface, non-wetting and non-reactive properties with most molten metals and semiconductor materials, high temperature resistance, and vacuum non-outgassing. Currently, pyrolytic boron nitride crucibles are commonly used for molecular beam epitaxy aluminum deposition. However, the industry has found that molten aluminum has a certain degree of wetting and corrosive effect on pyrolytic boron nitride crucibles, which may lead to aluminum seeping into the crucible and overflowing, corrosion of the crucible reducing its lifespan, and contamination of the molten aluminum. This makes it difficult to control the stability of the molecular beam and improve the quality of epitaxial products. Therefore, it is necessary to improve the resistance of existing pyrolytic boron nitride crucibles to aluminum immersion corrosion.

[0003] Patent CN105603388A discloses a method for preparing a long-life pyrolytic boron nitride crucible. It modifies the interlayer structure of the pyrolytic boron nitride crucible by intermittently stopping the gas flow during chemical vapor deposition, thereby extending the crucible's lifespan. However, it does not address how to improve the crucible's resistance to aluminum molten corrosion, failing to solve problems such as aluminum molten material wetting, corrosion, and overflow. Patent CN115637490A discloses a method for manufacturing an integrated molecular beam epitaxy crucible, an epitaxy crucible, and a molecular beam source furnace. It integrates heating wires into the pyrolytic boron nitride layer to improve thermal efficiency and heat field uniformity, but it does not consider improving the crucible's resistance to aluminum molten corrosion. The patent with publication number CN102586754A proposes a method for preparing an easy-to-demold pyrolytic boron nitride crucible. It achieves easy demolding by pre-coating with pyrolytic boron nitride, solving the problems of difficult demolding of pyrolytic boron nitride crucible and the need for grinding of the inner wall. By depositing the pre-coating first and then performing subsequent deposition, the demolding performance and inner wall smoothness are improved, but the crucible's resistance to aluminum melt wetting corrosion is not improved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a pyrolytic boron nitride crucible resistant to aluminum molten corrosion and its preparation method, thereby solving the problem that pyrolytic boron nitride crucibles are easily corroded by aluminum molten material, leading to aluminum molten material overflowing, reduced crucible lifespan, and aluminum molten material contamination, which affects the stability of molecular beams and the quality of epitaxial products.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A pyrolytic boron nitride crucible resistant to aluminum molten corrosion comprises a pyrolytic boron nitride crucible body and an aluminum molten corrosion resistant coating applied to its surface. The pyrolytic boron nitride crucible body is a thin-walled, hollow vessel with one open end made of pyrolytic boron nitride material. The aluminum nitride corrosion resistant coating is an aluminum nitride coating applied to all or part of the surface of the pyrolytic boron nitride crucible body.

[0007] The pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion has a crucible body thickness of 0.5–2 mm and an aluminum liquid wetting corrosion resistant coating thickness of 5–100 μm.

[0008] The aforementioned pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion has a portion of its surface being an inner surface, an outer surface, or a designated area surface.

[0009] The preparation method of the pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion includes the following steps:

[0010] The first step is to prepare the pyrolytic boron nitride crucible body;

[0011] The second step is to roughen the surface of the pyrolytic boron nitride crucible body.

[0012] The third step is to apply a coating that is resistant to corrosion from molten aluminum.

[0013] The preparation method of the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion includes the following first step: The process of preparing the pyrolytic boron nitride crucible body is as follows: A graphite mold is made according to the shape and size of the crucible required for molecular beam epitaxial aluminum plating. After surface polishing, dust removal, cleaning, and drying, the graphite mold is placed in a vacuum deposition furnace. Pyrolytic boron nitride is deposited on the surface of the graphite mold by adjusting the chemical vapor deposition process parameters. The deposition process parameters are: deposition temperature of 1200–2100℃, furnace pressure of 100–101325 Pa, nitrogen as dilution gas and carrier gas, boron trichloride as boron source, ammonia as nitrogen source, a molar ratio of boron trichloride to nitrogen source of 1:1–1:10, and deposition time of 3–20 hours. A pyrolytic boron nitride ceramic shell of 0.5–2.5 mm is deposited on the surface of the graphite mold. After furnace cooling, demolding, processing, and cleaning, the pyrolytic boron nitride crucible body of the required shape and size is obtained.

[0014] The second step in the preparation method of the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion is as follows: the surface roughening treatment of the pyrolytic boron nitride crucible body is carried out by the surface roughening treatment method to make the surface roughness Ra of the pyrolytic boron nitride crucible body uniform: 1~20μm, so as to achieve good matching and firm bonding between the pyrolytic boron nitride crucible body and the aluminum liquid wetting corrosion resistant coating.

[0015] The preparation method of the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion includes a surface roughening treatment method of grinding or sandblasting.

[0016] The preparation method of the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion, the third step, the process of applying the aluminum liquid wetting corrosion resistant coating is as follows: the pyrolytic boron nitride crucible body after surface roughening treatment is placed in a vacuum deposition furnace, and an aluminum nitride coating is uniformly applied to the surface of the pyrolytic boron nitride crucible body using a coating preparation method.

[0017] The method for preparing the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion includes a coating preparation method that is either chemical vapor deposition or plasma-enhanced chemical vapor deposition.

[0018] The method for preparing the pyrolytic boron nitride crucible resistant to aluminum molten corrosion, when using chemical vapor deposition, includes the following deposition process parameters: deposition temperature of 800–1600℃, furnace pressure of 100–101325 Pa, nitrogen as dilution gas and carrier gas, aluminum trichloride powder as aluminum source, ammonia as nitrogen source, a molar ratio of aluminum trichloride to ammonia of 1:1–1:10, maintaining the temperature of aluminum trichloride powder at 170–200℃, and deposition time of 10–200 minutes; an aluminum nitride coating of 5–100 μm thickness is prepared on the surface of the pyrolytic boron nitride crucible body; after cooling and cleaning, a pyrolytic boron nitride crucible with an aluminum nitride coating is obtained.

[0019] The design concept of this invention is:

[0020] This invention is based on the principle of surface and interface modification. It improves the resistance of the pyrolytic boron nitride crucible to aluminum molten metal corrosion by coating the surface with an aluminum nitride coating that exhibits superior resistance to aluminum molten metal wetting corrosion. A chemical vapor deposition method and a rough interface bonding mechanism are used to achieve a good match and strong bond between the pyrolytic boron nitride crucible body and the aluminum nitride coating, thereby preparing a pyrolytic boron nitride crucible resistant to aluminum molten metal wetting corrosion, suitable for molecular beam epitaxy aluminum-plating crucibles.

[0021] This invention employs a deposition temperature of 1200–2100℃ for pyrolytic boron nitride deposition and 800–1600℃ for aluminum nitride coating deposition. First, the pyrolytic boron nitride crucible body is prepared at a higher temperature (1200–2100℃) to ensure its dense structure and stable performance. Then, the AlN coating is deposited at a lower temperature (800–1600℃). This temperature gradient reduces the superposition of thermal stress from the two depositions, preventing overall structural deformation. The temperature parameters are designed based on a comprehensive optimization of material reaction mechanisms, interface matching requirements, and functional positioning, ensuring both the fundamental properties of the pyrolytic boron nitride body and achieving resistance to molten aluminum corrosion and structural stability of the aluminum nitride coating.

[0022] The crucible body of this invention is a thin-walled, hollow, one-end-open vessel made of pyrolytic boron nitride, with a thickness of 0.5–2 mm. In molecular beam epitaxy (MBE), the crucible requires rapid heat transfer to precisely control the evaporation rate of the molten aluminum. An excessively thick body (>2 mm) will lead to a delayed thermal response, affecting the stability of the molecular beam; an excessively thin body (<0.5 mm) cannot guarantee structural strength and is prone to deformation or cracking at high temperatures. The aluminum molten aluminum wetting and corrosion resistant coating applied to the surface of the crucible body is made of aluminum nitride, with a thickness of 5–100 μm. If the thickness is <5 μm, uneven deposition may cause the molten aluminum to directly contact the crucible body, leading to corrosion or wetting problems. Due to the difference in thermal expansion coefficients between AlN and PBN, an excessively thick coating (>100 μm) is prone to cracking and peeling due to stress release, losing its protective function.

[0023] The present invention employs appropriate surface roughening treatment methods (such as grinding or sandblasting techniques) to make the surface of the pyrolytic boron nitride crucible body exhibit a uniform surface roughness Ra: 1-20μm, which is conducive to the good matching and firm bonding between the crucible body and the coating, and avoids defects such as blistering, peeling, and cracking.

[0024] The advantages and beneficial effects of this invention are:

[0025] (1) The present invention provides a pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion, which is composed of a pyrolytic boron nitride crucible body and an aluminum nitride coating resistant to aluminum liquid wetting corrosion applied to its surface, and is suitable for molecular beam epitaxy aluminum plating crucible.

[0026] This invention retains the excellent properties of the pyrolytic boron nitride crucible body (such as high purity and high temperature resistance) while making full use of the superior resistance of the aluminum nitride coating to aluminum molten corrosion—the aluminum molten material hardly wets the aluminum nitride (contact angle >120°) and does not undergo significant chemical corrosion reaction with the aluminum nitride. This effectively isolates and protects the pyrolytic boron nitride from the aluminum molten material, which can greatly avoid adverse phenomena such as aluminum molten material wetting the crucible and overflowing, corrosion of the crucible and reduced crucible life, and contamination of the aluminum molten material. In this way, it can effectively control the stability of the molecular beam and improve the quality of epitaxial products.

[0027] (2) The present invention provides a method for preparing a pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion. The method has simple and easy implementation steps, short process flow, low production cost, and can be continuously produced. It is suitable for preparing molecular beam epitaxial aluminum-plated crucibles.

[0028] This invention enables the preparation of pyrolytic boron nitride crucible bodies with performance requirements higher, lower, or equivalent to those of existing pyrolytic boron nitride crucibles by adjusting chemical vapor deposition process parameters. This allows for optimization and adjustment of the crucible body's performance suitability based on the principle of applicability to molecular beam epitaxy aluminum-plated crucibles. Furthermore, chemical vapor deposition can be used to prepare an aluminum nitride coating of appropriate thickness and continuous density on all or part of the surface of the pyrolytic boron nitride crucible body, thus meeting the requirements for resistance to aluminum molten corrosion. Finally, a rough interface bonding mechanism ensures good matching and strong bonding between the pyrolytic boron nitride crucible body and the aluminum nitride coating, resulting in long-lasting resistance to immersion corrosion. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a pyrolytic boron nitride crucible without an aluminum molten corrosion resistant coating. In the diagram: 1 is the pyrolytic boron nitride crucible body, 3 is the aluminum molten material, and 4 is the aluminum molten material overflowing from the crucible.

[0030] Figure 2 This is a schematic diagram of the structure of the pyrolytic boron nitride crucible resistant to aluminum liquid wetting corrosion according to the present invention; in the figure: 1 is the pyrolytic boron nitride crucible body, 2 is the aluminum liquid wetting corrosion resistant coating, and 3 is the aluminum liquid. Detailed Implementation

[0031] like Figure 1 As shown, in the process of molecular beam epitaxy aluminum plating, the aluminum liquid 3 of the existing pyrolytic boron nitride crucible is prone to wetting and corroding the pyrolytic boron nitride crucible body 1, resulting in aluminum liquid overflow 4, which shortens the life of the pyrolytic boron nitride crucible, causes aluminum liquid contamination and molecular beam instability.

[0032] In its implementation, this invention achieves a good match and firm bond between the pyrolytic boron nitride crucible body and the aluminum melt resistant coating through chemical vapor deposition and a roughened interface mechanism, thereby ensuring long-term resistance to aluminum melt corrosion. The pyrolytic boron nitride crucible of this invention consists of a pyrolytic boron nitride crucible body and an aluminum melt resistant coating applied to its surface. The surface refers to all or part of the surface of the pyrolytic boron nitride crucible body (e.g., the inner surface, outer surface, or a specific area). Because the aluminum melt resistant coating effectively isolates and protects the pyrolytic boron nitride from the aluminum melt, it significantly avoids adverse phenomena such as aluminum melt wetting the crucible and overflowing, corrosion of the crucible reducing its lifespan, and contamination of the aluminum melt. This, in turn, effectively controls molecular beam stability and improves the quality of epitaxial products.

[0033] To better understand the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0034] Example 1

[0035] In this embodiment, a method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion is achieved through the following steps:

[0036] The first step is to prepare the pyrolytic boron nitride crucible body;

[0037] A graphite mold was fabricated according to the shape and size of the crucible required for molecular beam epitaxy aluminum deposition. After surface polishing, dust removal, cleaning, and drying, the graphite mold was placed in a vacuum deposition furnace. Pyrolytic boron nitride was deposited on the surface of the graphite mold by adjusting the chemical vapor deposition process parameters. The deposition process parameters were: deposition temperature of 1900℃, furnace pressure of 200Pa, nitrogen as dilution gas and carrier gas, boron trichloride (BCl3) as boron source, and ammonia (NH3) as nitrogen source, with a BCl3:NH3 molar ratio of 1:3, and a deposition time of 9 hours. A pyrolytic boron nitride ceramic shell with a thickness of approximately 1 mm was deposited on the surface of the graphite mold. After furnace cooling, demolding, processing, and cleaning, the pyrolytic boron nitride crucible body of the required shape and size, with a thickness of 0.8 mm, was obtained.

[0038] The second step is to roughen the surface of the pyrolytic boron nitride crucible body.

[0039] The surface roughness Ra of the pyrolysis boron nitride crucible body is made uniform by using a sanding technique. This is conducive to the good matching and firm bonding between the pyrolysis boron nitride crucible body and the coating, and avoids defects such as blistering, peeling, and cracking.

[0040] The third step is to apply an aluminum nitride coating.

[0041] The pyrolytic boron nitride crucible body, after surface roughening treatment, was placed in a vacuum deposition furnace. An aluminum nitride coating was uniformly applied to the surface of the crucible body using chemical vapor deposition. The deposition parameters were: deposition temperature of 1200℃, furnace pressure of 300 Pa, nitrogen as dilution and carrier gas, aluminum trichloride (AlCl3) powder as the aluminum source, and ammonia (NH3) as the nitrogen source. The temperature of aluminum trichloride was maintained at 195℃, the molar ratio of AlCl3 to NH3 was 1:4, and the deposition time was 40 minutes. An aluminum nitride coating approximately 20 μm thick was obtained on the surface of the pyrolytic boron nitride crucible body. After cooling and cleaning, the pyrolytic boron nitride crucible with the aluminum nitride coating was obtained.

[0042] like Figure 2As shown, the pyrolytic boron nitride crucible resistant to aluminum molten metal corrosion in this embodiment consists of a pyrolytic boron nitride crucible body 1 and an aluminum molten metal corrosion-resistant coating 2 applied to its surface. The pyrolytic boron nitride crucible body 1 is a thin-walled, hollow vessel with one open end made of pyrolytic boron nitride material, with a thickness of 0.8 mm. The aluminum molten metal corrosion-resistant coating 2 is an aluminum nitride coating with a thickness of 20 μm, and the coating surface covers the entire surface of the pyrolytic boron nitride crucible body 1. When the resulting crucible is immersed in molten aluminum at 900°C for 2 hours, the contact angle is 125°±3°, preventing the pyrolytic boron nitride crucible from being corroded by the molten aluminum. The molten aluminum 3 does not wet the aluminum nitride coating at all, and there is no aluminum molten metal overflowing from the crucible. This crucible is suitable for molecular beam epitaxy aluminum plating crucibles.

[0043] Example 2

[0044] In this embodiment, a method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion is achieved through the following steps:

[0045] The first step is to prepare the pyrolytic boron nitride crucible body;

[0046] A graphite mold is fabricated according to the shape and size of the crucible required for molecular beam epitaxy (MBE) aluminum deposition. After surface polishing, dust removal, cleaning, and drying, the graphite mold is placed in a vacuum deposition furnace. Pyrolytic boron nitride is deposited on the surface of the graphite mold by adjusting the chemical vapor deposition (CVD) process parameters. The deposition parameters are: deposition temperature of 2000℃, furnace pressure of 300Pa, nitrogen as dilution and carrier gas, boron trichloride (BCl3) as boron source, and ammonia (NH3) as nitrogen source, with a BCl3:NH3 molar ratio of 1:5, and a deposition time of 16 hours. A pyrolytic boron nitride ceramic shell with a thickness of approximately 1.5 mm is deposited on the surface of the graphite mold. After furnace cooling, demolding, processing, and cleaning, the pyrolytic boron nitride crucible body of the required shape and size is obtained.

[0047] The second step is to roughen the surface of the pyrolytic boron nitride crucible body.

[0048] Sandblasting technology is used to make the surface of the pyrolytic boron nitride crucible body have a uniform surface roughness Ra: 4-6μm, which is conducive to the good matching and firm bonding between the pyrolytic boron nitride crucible body and the coating, and avoids defects such as blistering, peeling, and cracking.

[0049] The third step is to apply an aluminum nitride coating.

[0050] The pyrolytic boron nitride crucible body, after surface roughening treatment, was placed in a vacuum deposition furnace. An aluminum nitride coating was uniformly applied to the surface of the crucible body using chemical vapor deposition. The deposition parameters were: deposition temperature of 1400℃, furnace pressure of 200 Pa, nitrogen as dilution and carrier gas, aluminum trichloride (AlCl3) powder as the aluminum source, and ammonia (NH3) as the nitrogen source. The temperature of aluminum trichloride was maintained at 180℃, the molar ratio of AlCl3 to NH3 was 1:5, and the deposition time was 50 minutes. A 25 μm thick aluminum nitride coating was obtained on the surface of the pyrolytic boron nitride crucible body. After cooling and cleaning, the pyrolytic boron nitride crucible with the aluminum nitride coating was obtained.

[0051] like Figure 2 As shown, the pyrolytic boron nitride crucible resistant to aluminum molten metal corrosion in this embodiment consists of a pyrolytic boron nitride crucible body 1 and an aluminum molten metal corrosion resistant coating 2 applied to its surface. The pyrolytic boron nitride crucible body 1 is a thin-walled, hollow vessel with one open end made of pyrolytic boron nitride material, with a thickness of 1.2 mm. The aluminum molten metal corrosion resistant coating 2 is an aluminum nitride coating with a thickness of 50 μm, and the coating surface covers the entire surface of the pyrolytic boron nitride crucible body 1. When the resulting crucible is immersed in 900°C molten aluminum for 2 hours, the contact angle is 131°±2°, preventing the pyrolytic boron nitride crucible from being corroded by the molten aluminum. The molten aluminum 3 does not wet the aluminum nitride coating at all, and there is no aluminum molten metal overflowing from the crucible. This crucible is suitable for molecular beam epitaxy aluminum plating crucibles.

[0052] The results show that the present invention adopts a combination design of pyrolytic boron nitride body, aluminum nitride coating and surface roughening. The aluminum nitride coating solves the problem of aluminum liquid corrosion. Combined with specific roughness and deposition parameters, it can significantly improve the crucible's resistance to aluminum liquid wetting corrosion. Moreover, the process is stable and easy to industrialize.

Claims

1. A pyrolytic boron nitride crucible resistant to aluminum molten metal wetting corrosion, characterized in that, It consists of a pyrolytic boron nitride crucible body and an aluminum molten metal corrosion resistant coating applied to its surface. The pyrolytic boron nitride crucible body is a thin-walled, hollow vessel with one open end made of pyrolytic boron nitride material. The aluminum molten metal corrosion resistant coating is an aluminum nitride coating, which is applied to all or part of the surface of the pyrolytic boron nitride crucible body.

2. The pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 1, characterized in that, The thickness of the pyrolytic boron nitride crucible body is 0.5–2 mm, and the thickness of the aluminum melt immersion corrosion resistant coating is 5–100 μm.

3. The pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 1, characterized in that, Some surfaces are inner surfaces, outer surfaces, or surfaces in a designated area.

4. A method for preparing a pyrolytic boron nitride crucible resistant to aluminum molten corrosion as described in any one of claims 1 to 3, characterized in that, Includes the following steps: The first step is to prepare the pyrolytic boron nitride crucible body; The second step is to roughen the surface of the pyrolytic boron nitride crucible body. The third step is to apply a coating that is resistant to corrosion from molten aluminum.

5. The method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 4, characterized in that, The first step, the process of preparing the pyrolytic boron nitride crucible body, is as follows: A graphite mold is made according to the shape and size of the crucible required for molecular beam epitaxy aluminum deposition. After surface polishing, dust removal, cleaning, and drying, the graphite mold is placed in a vacuum deposition furnace. Pyrolytic boron nitride is deposited on the surface of the graphite mold by adjusting the chemical vapor deposition process parameters. The deposition process parameters are: deposition temperature of 1200–2100℃, furnace pressure of 100–101325 Pa, nitrogen as dilution gas and carrier gas, boron trichloride as boron source, ammonia as nitrogen source, a molar ratio of boron trichloride to nitrogen source of 1:1–1:10, and deposition time of 3–20 hours. A pyrolytic boron nitride ceramic shell of 0.5–2.5 mm is deposited on the surface of the graphite mold. After furnace cooling, demolding, processing, and cleaning, the pyrolytic boron nitride crucible body of the required shape and size is obtained.

6. The method for preparing the pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 5, characterized in that, The second step, the surface roughening treatment of the pyrolytic boron nitride crucible body, is as follows: The surface roughening treatment method is used to make the surface of the pyrolytic boron nitride crucible body have a uniform surface roughness Ra: 1~20μm, so as to achieve good matching and firm bonding between the pyrolytic boron nitride crucible body and the aluminum liquid immersion corrosion resistant coating.

7. The method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 6, characterized in that, The surface roughening treatment methods are abrasion or sandblasting.

8. The method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 6, characterized in that, The third step, the process of applying a coating resistant to aluminum liquid wetting corrosion, is as follows: The pyrolytic boron nitride crucible body, after surface roughening treatment, is placed in a vacuum deposition furnace, and an aluminum nitride coating is uniformly applied to the surface of the pyrolytic boron nitride crucible body using a coating preparation method.

9. The method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 8, characterized in that, The coating is prepared by chemical vapor deposition or plasma-enhanced chemical vapor deposition.

10. The method for preparing a pyrolytic boron nitride crucible resistant to aluminum melt wetting corrosion according to claim 9, characterized in that, When using chemical vapor deposition, the deposition process parameters are as follows: deposition temperature of 800–1600℃, furnace pressure of 100–101325 Pa, nitrogen as dilution gas and carrier gas, aluminum trichloride powder as aluminum source, ammonia as nitrogen source, the molar ratio of aluminum trichloride to ammonia of 1:1–1:10, maintaining the temperature of aluminum trichloride powder at 170–200℃, and deposition time of 10–200 minutes; an aluminum nitride coating of 5–100 μm thickness is prepared on the surface of the pyrolytic boron nitride crucible. After cooling and cleaning, a pyrolytic boron nitride crucible with an aluminum nitride coating is obtained.

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