Preparation method of crucible

Abstract

The invention discloses a preparation method of a crucible, the crucible comprises a crucible body and a silicon oxide coating, the crucible body is a quartz piece, the silicon oxide coating is arranged on the inner wall of the crucible body, the preparation method of the crucible comprises the following steps: preparing electrophoresis slurry, the electrophoresis slurry comprises quartz powder and a solvent; performing electrophoretic deposition on a silicon oxide coating on the inner wall of the crucible body by using an electrophoresis device to form a green body; and the green body is dried and sintered, and the crucible is prepared and formed. According to the preparation method of the crucible disclosed by the embodiment of the invention, the thickness of the silicon oxide coating of the crucible prepared by the preparation method is controllable, the uniformity is relatively good, when the crucible is used as a container for purifying a silicon material, the silicon oxide coating can better prevent impurities in the crucible body from entering the silicon material, and the surface of the silicon oxide coating is relatively rough, so that the silicon oxide coating is more uniform. A coating, such as a silicon nitride coating, which is further processed on the outer side of the silicon oxide coating is not easy to fall off, so that the pan sticking rate is reduced.

Description

Technical Field

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

[0002] In the process of purifying silicon using quartz crucibles, the purified silicon needs to possess characteristics such as low boron, low carbon, and low metal content. Therefore, the purity requirements for the quartz crucibles are relatively high. Quartz crucibles are generally produced using a casting process, resulting in a crucible body with many impurities and low purity, making it difficult to meet the usage requirements. Therefore, during crucible preparation, a high-purity silicon oxide layer is usually attached to the inner wall of the crucible. The high purity of this layer reduces the metal content of the produced silicon. Then, a silicon nitride layer is attached to the outside of the high-purity layer to prevent the silicon in the purified silicon from adhering to the inner wall of the crucible during the purification process.

[0003] In related technologies, the crucible is prepared by manually brushing a slurry onto the inner wall of the crucible to form a high-purity layer, followed by low-temperature drying to ensure adhesion. However, this method results in poor control over the thickness of the high-purity layer, leading to uneven thickness and lower quality. Consequently, the purity of the silicon material is reduced when purifying silicon using a quartz crucible. Furthermore, the smooth surface of the brush-coated high-purity layer results in poor adhesion of the silicon nitride layer, making it prone to detachment. This causes the silicon in the purified silicon material to adhere more easily to the inner wall of the crucible, resulting in a high rate of sticking. Therefore, improvements are needed. Summary of the Invention

[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, one object of the present invention is to provide a method for preparing a crucible in which the thickness of the silicon oxide coating is controllable and the uniformity is good. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body from entering the silicon material. Moreover, the surface of the silicon oxide coating is relatively rough, making it less likely for further processing coatings on the outside of the silicon oxide coating, such as silicon nitride coatings, to fall off, thereby reducing the sticking rate.

[0005] According to an embodiment of the present invention, a method for preparing a crucible includes a crucible body and a silicon oxide coating. The crucible body is a quartz component, and the silicon oxide coating is disposed on the inner wall of the crucible body. The method for preparing the crucible includes: An electrophoretic slurry is prepared, the electrophoretic slurry comprising quartz powder, silica sol, solvent, and pH adjuster; A silicon oxide coating is electrophoretically deposited on the inner wall of the crucible body using an electrophoretic apparatus to form a green part; The green part is dried and sintered to prepare the crucible.

[0006] According to the crucible preparation method of the present invention, an electrophoretic slurry is prepared, and a silicon oxide coating is electrophoretically deposited on the inner wall of the crucible body using an electrophoretic device. The thickness of the silicon oxide coating deposited on the crucible body can be controlled by adjusting the deposition time of the quartz powder, thereby adjusting the silicon oxide deposition time according to actual needs to prepare a silicon oxide coating of appropriate thickness. Furthermore, the electrophoretic device deposits the quartz powder in the electrophoretic slurry onto the inner wall of the crucible body, which can improve the uniformity of the silicon oxide coating. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body from entering the silicon material, resulting in higher purity of the silicon material. The quartz powder is deposited in particulate form on the inner wall of the crucible body, which can also improve the roughness of the silicon oxide coating, making it less likely for the coating to be further processed on the outside of the silicon oxide coating to fall off. For example, when a silicon nitride coating is attached to the outside of the silicon oxide coating, the adhesion of the silicon nitride coating is stronger and less likely to fall off, thereby reducing the sticking rate.

[0007] According to some embodiments of the present invention, the purity of the quartz powder is greater than or equal to 99.995%; and / or, the particle size range of the quartz powder is 100-300 μm.

[0008] According to some embodiments of the present invention, the solvent is an organic solvent or water; and / or, the electrophoretic slurry further includes a pH adjuster, wherein the pH adjuster is ammonia.

[0009] According to some embodiments of the present invention, the quartz powder in the electrophoretic slurry is 60-80 wt% by mass.

[0010] According to some embodiments of the present invention, the preparation of the electrophoretic slurry includes: mixing the quartz powder and the solvent, and then dispersing them thoroughly by ball milling or ultrasonic vibration; or mixing the quartz powder, the silica sol, the solvent and the pH adjuster, and then dispersing them thoroughly by ball milling or ultrasonic vibration.

[0011] According to some embodiments of the present invention, a silicon oxide coating is electrophoretically deposited on the inner wall of a crucible body using an electrophoresis apparatus, comprising: the electrophoresis apparatus including an electrophoresis container, a positive electrode and a negative electrode, the crucible body as the positive electrode, a platinum-plated electrode as the negative electrode, pure water being placed in the electrophoresis container, the crucible body being placed inside the electrophoresis container, the platinum-plated electrode being placed inside the crucible body and spaced apart from the inner wall of the crucible body to form an electrophoresis gap, the electrophoresis gap containing the electrophoretic slurry.

[0012] According to some embodiments of the present invention, the distance between the positive electrode and the negative electrode is uniform; and / or, the distance between the positive electrode and the negative electrode is 2-4 cm.

[0013] According to some embodiments of the present invention, the electrophoresis apparatus uses a DC voltage and the range of the DC voltage is 50-150 V.

[0014] According to some embodiments of the present invention, drying and sintering the green part includes drying the green part at a temperature of 25-120°C for 12-24 hours.

[0015] According to some embodiments of the present invention, drying and sintering the green part includes: sintering in a vacuum or argon / helium protective atmosphere, with a sintering temperature between 1100°C and 1300°C and a holding time of 1-2 hours.

[0016] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a schematic flowchart of a method for preparing a crucible according to some embodiments of the present invention; Figure 2 This is a schematic diagram of an electrophoresis apparatus according to some embodiments of the present invention.

[0018] Figure label: 100. Electrophoresis apparatus; 10. Electrophoresis container; 20. Crucible body; 30. Platinum-plated electrode; 40. Pure water; 50. Electrophoresis slurry. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] The following is for reference. Figures 1-2 A method for preparing a crucible according to an embodiment of the present invention is described.

[0021] refer to Figure 1 According to the crucible preparation method of the present invention, the crucible includes a crucible body 20 and a silicon oxide coating. The crucible body 20 is a quartz component, and the silicon oxide coating is disposed on the inner wall of the crucible body 20. The crucible preparation method includes: Electrophoretic slurry 50 is prepared, which includes quartz powder, silica sol, solvent and pH adjuster. By dispersing quartz powder in solvent to form a suspension, the quartz powder can be made fluid in solvent, which facilitates the directional movement of quartz powder in subsequent steps. By using silica sol and pH adjuster, the quartz powder can be better dispersed and prevented from agglomerating. A silicon oxide coating is electrophoretically deposited on the inner wall of the crucible body 20 using an electrophoresis apparatus 100 to form a green part. For example, the electrophoresis apparatus 100 can direct the quartz powder in the electrophoresis slurry 50 toward the inner wall of the crucible body 20, so that the quartz powder is deposited on the inner wall of the crucible body 20 to form a silicon oxide coating. By directly depositing the quartz powder on the inner wall of the crucible body 20 through the electrophoresis apparatus 100, the uniformity of the silicon oxide coating can be improved, and uneven thickness of the silicon oxide coating can be avoided. The particulate quartz powder can also improve the roughness of the silicon oxide coating, making it less likely for the coating to be further processed on the outside of the silicon oxide coating to fall off. For example, when a silicon nitride coating is attached to the outside of the silicon oxide coating, the adhesion of the silicon nitride coating is stronger and less likely to fall off, thereby reducing the sticking rate. Furthermore, the thickness of the silicon oxide coating deposited on the crucible body 20 by the electrophoresis apparatus 100 can be controlled by controlling the deposition time of the quartz powder, so that the silicon oxide deposition time can be adjusted according to the actual needs to prepare a silicon oxide coating of appropriate thickness. The green part is dried and sintered to form a crucible. By drying and sintering the green part, the structural strength of the silicon oxide coating can be improved, and a stable chemical bond can be formed between the silicon oxide coating and the crucible substrate, thereby improving the adhesion of the silicon oxide coating to the crucible substrate.

[0022] For example, the prepared crucible can be used as a container for purposes such as purifying and smelting raw materials and for thermal decomposition reactions of materials.

[0023] According to the crucible preparation method of the present invention, an electrophoretic slurry 50 is prepared, and a silicon oxide coating is electrophoretically deposited on the inner wall of the crucible body 20 using an electrophoretic apparatus 100. The thickness of the silicon oxide coating deposited on the crucible body 20 can be controlled by adjusting the deposition time of the quartz powder, thereby adjusting the silicon oxide deposition time according to actual needs to prepare a silicon oxide coating of suitable thickness. Furthermore, the electrophoretic apparatus 100 deposits the quartz powder in the electrophoretic slurry 50 onto the inner wall of the crucible body 20, which can improve the uniformity of the silicon oxide coating. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in higher purity of the silicon material. The quartz powder is deposited in particulate form on the inner wall of the crucible body 20, which can also improve the roughness of the silicon oxide coating, making it less likely for the coating to be further processed on the outside of the silicon oxide coating to fall off. For example, when a silicon nitride coating is attached to the outside of the silicon oxide coating, the adhesion of the silicon nitride coating is stronger and less likely to fall off, thereby reducing the sticking rate.

[0024] According to some embodiments of the present invention, the purity of the quartz powder is greater than or equal to 99.995%.

[0025] The purity of the quartz powder is greater than or equal to 99.995%, meaning that the main component of the quartz powder accounts for more than or equal to 99.995% of the total mass of the quartz powder, while the impurity components account for less than 0.005% of the total mass of the quartz powder. For example, the purity of the quartz powder can be 99.995%, 99.996%, 99.997%, etc.

[0026] By ensuring that the purity of quartz powder is greater than or equal to 99.995%, the impurity content in the silica coating formed by the quartz powder can be reduced, making the silica less susceptible to the influence of impurities in the silica coating when the crucible is used as a container for purifying silica.

[0027] According to some embodiments of the present invention, the particle size range of the quartz powder is 100-300 μm.

[0028] For example, the particle size range of quartz powder can be 100nm, 200nm, 300nm, etc. If the particle size of the quartz powder is too coarse, the quartz powder particles are prone to sedimentation, reducing the uniformity of the silicon oxide coating; if the particle size of the quartz powder is too fine, the quartz powder is prone to agglomeration when preparing the slurry, resulting in uneven thickness of the silicon oxide coating.

[0029] By making the particle size of the quartz powder range from 100 to 300 nm, it is beneficial to improve the uniformity of the silicon oxide coating. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material. It also makes the surface of the silicon oxide coating rougher, making the coating less likely to fall off during further processing of the crucible, thereby reducing the sticking rate.

[0030] According to some embodiments of the present invention, the solvent is an organic solvent or water.

[0031] For example, the organic solvent can be one of anhydrous ethanol or isopropanol.

[0032] By using an organic solvent or water as the solvent, and adding a certain proportion of silica sol and ammonia, the quartz powder is more easily dispersed in the solvent to form a suspension, which facilitates the deposition of the quartz powder onto the inner wall of the crucible body 20 in subsequent steps.

[0033] According to some embodiments of the present invention, the electrophoretic slurry 50 further includes a pH adjuster, which is ammonia.

[0034] Quartz powder is difficult to conduct electricity at room temperature. When quartz powder is dispersed in a solvent, ammonia water provides OH-. -Ions adjust the pH of the solvent to an alkaline range, for example, pH 9-11. Under this pH environment, the silanol groups (Si-OH) on the surface of silica will dissociate in large numbers into negatively charged Si-O groups. - This causes a sharp increase in the negative charge density on the surface of the quartz powder, leading to a shift in the Zeta potential of the quartz powder particles (the Zeta potential is the potential difference formed at the sliding surface when a particle is in contact with a liquid) towards the negative direction. This results in a larger absolute value of the Zeta potential. Since the particles are all negatively charged, the resulting electrostatic repulsion is strong. When this repulsion is sufficiently large, it can overcome the van der Waals attraction between the quartz powder particles, thus preventing quartz powder agglomeration and maintaining a stable dispersion of the slurry.

[0035] By including a pH adjuster in the electrophoretic slurry 50, and making the pH adjuster ammonia, the quartz powder can be negatively charged, which facilitates the directional movement of the quartz powder under the action of the electric field and its deposition on the inner wall of the crucible body 20. The pH adjuster can also make the quartz powder in the electrophoretic slurry 50 uniformly dispersed, avoiding the agglomeration of the quartz powder, and making the silicon oxide coating deposited on the crucible body 20 more uniform. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in higher purity of the silicon material.

[0036] According to some embodiments of the present invention, the mass percentage of quartz powder in the electrophoretic slurry 50 is 60-80 wt%.

[0037] For example, the mass percentage of quartz powder in the electrophoretic slurry 50 can be 60wt%, 70wt%, 80wt%, etc. If the concentration of quartz powder is too low, the deposition efficiency of the silicon oxide coating will be low; if the concentration of quartz powder is too high, the viscosity of the electrophoretic slurry 50 will be too high, the fluidity will be poor, and the uniformity of the silicon oxide coating thickness will be reduced during the deposition process.

[0038] By making the mass percentage of quartz powder in the electrophoretic slurry 50 60-80 wt%, the deposition efficiency of the silicon oxide coating can be higher, and the thickness uniformity of the silicon oxide coating can be higher. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, thus making the silicon material more pure.

[0039] According to some embodiments of the present invention, the preparation of electrophoretic slurry 50 includes: mixing quartz powder and solvent and then dispersing them thoroughly by ball milling or ultrasonic vibration; or mixing quartz powder, silica sol, solvent and pH adjuster and then dispersing them thoroughly by ball milling or ultrasonic vibration.

[0040] For example, the mass percentage of silica sol can be 5%-20%, and the amount of ammonia added can be adjusted according to the pH value of the electrophoretic slurry, with the pH value adjustment range being 9-11.

[0041] By using ball milling or ultrasonic vibration, quartz powder can be fully dispersed in the solvent, breaking down large agglomerated particles into uniform small quartz powder particles, forming a stable and uniform suspension. This makes the electrophoretic slurry 50 more uniform, which is beneficial for improving the uniformity of the silicon oxide coating during the deposition process. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in higher purity of the silicon material.

[0042] refer to Figure 2 According to some embodiments of the present invention, a silicon oxide coating is electrophoretically deposited on the inner wall of a crucible body 20 using an electrophoresis apparatus 100, comprising: the electrophoresis apparatus 100 including an electrophoresis container 10, a positive electrode and a negative electrode, the crucible body 20 being used as the positive electrode, a platinum-plated electrode 30 being used as the negative electrode, pure water 40 being placed in the electrophoresis container 10, the crucible body 20 being placed in the electrophoresis container 10, the platinum-plated electrode 30 being placed in the crucible body 20, the platinum-plated electrode 30 being an inert electrode that is not easily contaminated by the electrophoresis slurry 50, and the platinum-plated electrode 30 being spaced apart from the inner wall of the crucible body 20 to form an electrophoresis gap, the electrophoresis gap containing the electrophoresis slurry 50.

[0043] Platinum-plated electrodes are made by plating platinum onto the outer periphery of an electrode. For example, platinum plating can be applied to the outer layer of a stainless steel electrode to obtain a platinum-plated electrode.

[0044] The quartz crucible body 20 is difficult to conduct electricity at room temperature. To address this, pure water 40 is placed inside the electrophoresis container 10, and the crucible body 20 is then placed within the container. The main component of the quartz crucible is silicon dioxide, and its surface typically contains silanol (Si-OH) groups. Water molecules are polar molecules, with negatively charged oxygen atoms and positively charged hydrogen atoms. When the quartz crucible is immersed in pure water, the oxygen atoms in the water molecules preferentially adsorb onto the silicon atoms on the quartz surface, while the hydrogen atoms face outwards. This adsorption results in a localized accumulation of negative charges on the quartz surface, but the remaining unbalanced positive charges (such as H+) remain. + This charge will remain on the surface, thus giving the quartz crucible a positive charge.

[0045] For example, under energized conditions, a direct current electric field is formed between the platinum-plated negative electrode 30 and the crucible body 20, the positive electrode. Under the action of the direct current electric field, the negatively charged quartz powder in the electrophoretic slurry 50 moves towards the positively charged crucible body 20. The quartz powder that moves to the inner wall surface of the crucible body 20 loses its negative charge. Under the action of electric field force and van der Waals force, the quartz powder gradually deposits and accumulates on the inner wall surface of the crucible body 20, eventually forming a dense silicon oxide coating. The longer the deposition time, the thicker the prepared silicon oxide coating; the shorter the deposition time, the thinner the prepared silicon oxide coating.

[0046] By using an electrophoretic device 100 to electrophoretically deposit a silicon oxide coating on the inner wall of the crucible body 20, the uniformity of the silicon oxide coating can be improved. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in higher purity of the silicon material. By controlling the deposition time of quartz powder, the thickness of the silicon oxide coating can also be controlled. Thus, the deposition time of quartz powder can be adjusted according to actual needs to prepare a silicon oxide coating of appropriate thickness. Furthermore, the direct deposition of quartz powder on the inner wall of the crucible body 20 can result in a higher roughness of the silicon oxide coating, making it less likely for the coating to be further processed on the outside of the silicon oxide coating to fall off. For example, when a silicon nitride coating is attached to the outside of the silicon oxide coating, the adhesion of the silicon nitride coating is stronger and it is less likely to fall off, thereby reducing the sticking rate.

[0047] According to some embodiments of the present invention, the distance between the positive and negative electrodes is uniform. If the distance between the positive and negative electrodes is uneven, the rate at which the quartz powder in the electrophoretic slurry 50 moves towards the negative electrode will be too fast or too slow, resulting in uneven thickness of the silicon oxide coating deposited on the inner wall of the crucible body 20. By making the distance between the positive and negative electrodes uniform, the electric field strength between the positive and negative electrodes can be made uniform, thereby making the thickness of the deposited silicon oxide coating uniform. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in higher purity of the silicon material.

[0048] According to some embodiments of the present invention, the distance between the positive electrode and the negative electrode is 2-4 cm.

[0049] For example, the distance between the positive and negative electrodes can be 2cm, 2.5cm, 3cm, 3.5cm, 4cm, etc. If the distance between the positive and negative electrodes is too close, it is easy to cause a short circuit between the electrodes; if the distance between the positive and negative electrodes is too far, the electric field strength will be weakened, which will reduce the rate at which the quartz powder moves towards the negative electrode and reduce the efficiency of silicon oxide coating preparation.

[0050] By setting the distance between the positive and negative electrodes to 2-4 cm, the efficiency of silicon oxide coating preparation can be improved while maintaining a safe distance between the electrodes.

[0051] According to some embodiments of the present invention, the electrophoresis apparatus 100 uses a DC voltage, and the DC voltage ranges from 50 to 150 V.

[0052] For example, the DC voltage of the electrophoresis apparatus 100 can be 50V, 70V, 90V, 110V, 130V, etc. If the DC voltage used in the electrophoresis apparatus 100 is too high, the silicon oxide coating will be deposited too quickly, which will easily lead to a loose silicon oxide coating and the formation of bubbles, causing the silicon oxide coating to fall off; if the DC voltage used in the electrophoresis apparatus 100 is too low, the silicon oxide coating will be deposited too slowly, which is not conducive to the efficient production of crucibles.

[0053] By setting the current voltage of the electrophoresis apparatus 100 to a range of 50-150 V, the silicon oxide coating on the crucible body 20 can be made denser and less prone to peeling while maintaining a suitable deposition rate.

[0054] According to some embodiments of the present invention, drying and sintering the green part includes drying the green part at a temperature of 25-120°C for 12-24 hours.

[0055] For example, drying temperatures can be 25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, etc. If the drying temperature is too high, the water molecules inside the green part will evaporate too quickly, making the green part prone to cracking. If the drying temperature is too low, it will not be conducive to the evaporation of moisture inside the green part.

[0056] For example, the drying time can be 12h, 16h, 20h, 24h, etc. If the drying time is too long, it is easy to cause the green part to crack; if the drying time is too short, it is not conducive to the evaporation of moisture in the green part.

[0057] By drying the green body at 25-120°C for 12-24 hours, the moisture inside the green body can be effectively removed, thus preventing cracking of the green body caused by the violent movement of water molecules during the subsequent high-temperature sintering process.

[0058] According to some embodiments of the present invention, drying and sintering the green part includes: sintering in a vacuum or argon / helium protective atmosphere, with a sintering temperature between 1100°C and 1300°C and a holding time of 1-2 hours.

[0059] For example, sintering can be carried out in a vacuum or argon / helium protective atmosphere. The green part can be sintered in an environment where air is evacuated, or in an environment where helium or argon is introduced.

[0060] For example, sintering temperatures can be 1100°C, 1150°C, 1200°C, 1250°C, 1300°C, etc. If the sintering temperature is too high, it is easy to reach the melting point of quartz, which will damage the green part; if the sintering temperature is too low, it is difficult to form a stable chemical bond between the silicon oxide coating and the crucible substrate.

[0061] For example, the holding temperature can be the highest temperature during the sintering of the green part, and the holding time can be 1 hour, 1 hour 20 minutes, 1 hour 40 minutes, 2 hours, etc. If the holding time is too long, the production efficiency of the crucible will be reduced; if the holding time is too short, it will be difficult to ensure that the green part is fully sintered.

[0062] By sintering the green part in a vacuum or argon / helium protective atmosphere, new impurities can be avoided from being introduced into the green part during the sintering process, maintaining a high purity of silicon oxide in the crucible body 20 and the silicon oxide coating. When the crucible is used as a container for purifying silicon material, the silicon oxide coating can better prevent impurities in the crucible body 20 from entering the silicon material, resulting in a high purity of silicon material. Furthermore, by sintering the green part at a temperature between 1100℃ and 1300℃ and holding it for 1-2 hours, the green part can be fully sintered, improving the structural strength of the silicon oxide coating and forming a stable chemical bond between the silicon oxide coating and the crucible substrate, making the silicon oxide coating less prone to peeling off, thereby extending the service life of the crucible.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0064] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for preparing a crucible, characterized in that, The crucible includes a crucible body and a silicon oxide coating. The crucible body is a quartz component, and the silicon oxide coating is disposed on the inner wall of the crucible body. The method for preparing the crucible includes: Prepare an electrophoretic slurry, wherein the electrophoretic slurry comprises quartz powder, silica sol, solvent, and pH adjuster; A silicon oxide coating is electrophoretically deposited on the inner wall of the crucible body using an electrophoretic apparatus to form a green part; The green part is dried and sintered to prepare the crucible.

2. The method for preparing the crucible according to claim 1, characterized in that, The purity of the quartz powder is greater than or equal to 99.995%; And / or, the particle size range of the quartz powder is 100-300 μm.

3. The method for preparing the crucible according to claim 1, characterized in that, The solvent is an organic solvent or water; And / or, the electrophoretic slurry further includes a pH adjuster, wherein the pH adjuster is ammonia.

4. The method for preparing the crucible according to claim 1, characterized in that, The quartz powder in the electrophoretic slurry is 60-80 wt% by mass.

5. The method for preparing the crucible according to claim 1, characterized in that, The preparation of the electrophoretic slurry includes: mixing the quartz powder and the solvent, and then dispersing them fully by ball milling or ultrasonic vibration; or mixing the quartz powder, the silica sol, the solvent and the pH adjuster, and then dispersing them fully by ball milling or ultrasonic vibration.

6. The method for preparing the crucible according to claim 1, characterized in that, The method of electrophoretically depositing a silicon oxide coating on the inner wall of a crucible body using an electrophoresis apparatus includes: the electrophoresis apparatus comprising an electrophoresis container, a positive electrode, and a negative electrode; the crucible body serving as the positive electrode; a platinum-plated electrode serving as the negative electrode; pure water being placed inside the electrophoresis container; the crucible body being placed inside the electrophoresis container; the platinum-plated electrode being placed inside the crucible body and spaced apart from the inner wall of the crucible body to form an electrophoresis gap; and the electrophoresis gap containing the electrophoretic slurry.

7. The method for preparing the crucible according to claim 6, characterized in that, The distance between the positive electrode and the negative electrode is uniform; And / or, the distance between the positive electrode and the negative electrode is 2-4 cm.

8. The method for preparing the crucible according to claim 6, characterized in that, The electrophoresis device uses a DC voltage, and the range of the DC voltage is 50-150 V.

9. The method for preparing a crucible according to any one of claims 1-8, characterized in that, Drying and sintering the green part includes drying the green part at a temperature of 25-120°C for 12-24 hours.

10. The method for preparing a crucible according to any one of claims 1-8, characterized in that, The process of drying and sintering the green part includes: sintering in a vacuum or argon / helium protective atmosphere at a sintering temperature between 1100°C and 1300°C for a holding time of 1-2 hours.

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