Quartz sand, quartz crucible, green body of quartz crucible and preparation method of green body

Abstract

The invention provides quartz sand, a quartz crucible, a green body of the quartz crucible and a preparation method of the green body, and belongs to the technical field of quartz sand separation and quartz crucible melting. The quartz sand has an alpha-quartz crystal form, the mass ratio of quartz sand particles with the density smaller than or equal to the first density is not larger than 4%, and the second density of the quartz sand is larger than or equal to 2.63 g / cm < 3 > and smaller than 2.66 g / cm < 3 >. The quartz sand is amorphous synthetic quartz sand, the mass ratio of the quartz sand particles with the density smaller than or equal to the first density is not larger than 4%, and the second density of the quartz sand is larger than or equal to 2.2 g / cm < 3 > and smaller than 2.3 g / cm < 3 >.

Description

Technical Field

[0001] This application relates to the fields of quartz sand sorting and quartz crucible melting technology. Specifically, this application relates to a quartz sand, a quartz crucible and its blank, and a preparation method. Background Technology

[0002] Quartz crucibles, used as melting containers for pulling monocrystalline silicon in photovoltaic or semiconductor applications, directly impact the crystal pulling effect of monocrystalline silicon rods, such as their yield or quality. Furthermore, as a critical consumable, the cost of quartz crucibles directly affects the cost of subsequent silicon wafers, and ultimately, the cost of photovoltaic modules or chips.

[0003] The quality and cost of quartz crucibles are largely based on the quality and cost of the main raw material, quartz sand. Currently, the industry controls the quality of quartz sand through purity; for example, quartz sand used in the photovoltaic and communications industries reaches a purity of 4N, while that used in the semiconductor or chip industry is at the 5N level. With advancements in mineral processing and purification technologies, the cost of quartz crucibles has significantly decreased. However, this has also led to instability in the quality of quartz crucibles and single-crystal silicon rods. This instability is mainly related to current purity testing methods. Currently, purity testing primarily relies on chemical analysis and ICP testing, which require small sample sizes and have poor representativeness. Furthermore, due to the low impurity content, this is considered low-impurity testing, which is difficult and prone to errors.

[0004] Therefore, there is an urgent need for a convenient and quick method to control the quality of quartz sand in actual production and to prepare quartz crucibles so that they can meet the cost and quality requirements of pulling single crystal silicon. Summary of the Invention

[0005] In view of the above, in order to at least partially solve at least one of the aforementioned technical problems, this application provides quartz sand, a quartz crucible and its blank, and a preparation method thereof.

[0006] To achieve the above objectives, the technical solution of this application is as follows:

[0007] According to one embodiment of this application, a quartz sand is provided, having an α-quartz crystal form, wherein the mass percentage of quartz sand particles with a first density less than or equal to 4% is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.63 g / cm³. 3 And less than 2.66 g / cm 3 .

[0008] According to another embodiment of this application, amorphous synthetic quartz sand is provided, wherein the mass percentage of quartz sand particles with a first density less than or equal to 4% is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm³.3 And less than 2.3 g / cm 3 .

[0009] According to another aspect of this application, a blank for a quartz crucible is provided, prepared from quartz sand as described above.

[0010] According to another embodiment of this application, a quartz crucible is provided, which is prepared using a quartz crucible blank as described above.

[0011] According to another embodiment of this application, a method for preparing a quartz crucible is provided, comprising: melting quartz sand to obtain a quartz crucible; wherein the quartz sand has an α-quartz crystal form, the mass percentage of quartz sand particles with a first density less than or equal to 4% is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.63 g / cm³. 3 And less than 2.66 g / cm 3 .

[0012] According to another embodiment of this application, a method for preparing a quartz crucible is provided, comprising: melting quartz sand to obtain a quartz crucible; wherein the quartz sand is amorphous synthetic quartz sand, the mass percentage of quartz sand particles with a first density less than or equal to 4% is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm³. 3 And less than 2.3 g / cm 3 .

[0013] The quartz sand provided in the embodiments of this application, by controlling its density distribution within the aforementioned range and removing quartz sand particles containing impurities and inclusions, can be precisely controlled to a higher quality. Consequently, the quality of the quartz crucibles melted using this quartz sand is also improved, exhibiting a higher crucible melting yield and better single-crystal silicon pulling effect. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0015] In the following detailed description, numerous specific details are set forth for ease of explanation to provide a thorough understanding of the embodiments of this application. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0016] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0017] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). When using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0018] In the related technologies for preparing quartz crucibles, the main raw material is crystalline natural quartz sand. Its quality directly affects the quality of the subsequently produced quartz crucibles and the effectiveness of single-crystal silicon pulling using quartz crucibles. Less commonly, amorphous synthetic quartz sand, prepared using chemical synthesis techniques (e.g., gas-phase synthesis, liquid-phase synthesis, fluorosilicic acid method), is also used as a raw material for quartz crucible production. Currently, the evaluation of the quality performance of crystalline quartz sand mainly focuses on appearance and impurity content, while the evaluation indicators for amorphous quartz sand are mainly referenced from those for crystalline quartz sand.

[0019] However, through extensive testing by the applicant, it was found that even when quartz sand that met the appearance and impurity content standards was used, the quartz crucibles made from it still had low quality.

[0020] Through continuous research, the applicant discovered that the main defective sand in quartz sand is inclusions (quartz sand particles containing bubbles, liquid phase, and impurities). These defective sand particles have low density and are easily introduced into the melting crucible. However, the relevant technologies lack effective methods for detecting such large batches of quartz sand, which has become a major challenge in further improving the quality of quartz sand and also affects the improvement of quartz crucible quality.

[0021] In realizing the concept of this application, it was discovered that by controlling the density distribution of quartz sand, the adverse effects of impurities, inclusions, and other factors can be effectively reduced, thereby precisely controlling the quartz sand to a higher quality. Consequently, quartz crucibles melted using this quartz sand exhibit a more consistent high quality.

[0022] Specifically, according to one embodiment of this application, a quartz sand is provided having an α-quartz crystal form, wherein the mass percentage of quartz sand particles with a first density less than or equal to 4% is no greater than 4%, and the second density of the quartz sand is greater than or equal to 2.63 g / cm³. 3 And less than 2.66 g / cm 3 .

[0023] In this application, "quartz sand" refers to multiple quartz sand particles with a crystalline structure, i.e., crystalline quartz sand such as α-quartz sand. It is understood that the "quartz sand" protected in this application refers to a batch of quartz sand used in the preparation of quartz crucibles, and each batch of quartz sand may be tens of kilograms, hundreds of kilograms or several tons, each containing countless quartz sand particles.

[0024] In this application, the "second density" refers to the process of gravity separation of quartz sand using a separation liquid. First, the separation liquid is used to make all the quartz sand float. Then, ethanol is used to reduce the density of the separation liquid in turn, so that most of the quartz sand is in suspension in the separation liquid, except for a few quartz sands that always float on the heavy liquid. At this time, the density of the separation liquid can be regarded as the second density of the quartz sand.

[0025] In this application, "first density" refers to the process of gravity separation of quartz sand using a separation liquid. After the quartz sand and the separation liquid reach a second density, ethanol is used to reduce the density of the separation liquid in sequence. After the addition is complete, the quartz sand floating on the separation liquid is allowed to stand, causing the quartz sand to separate into layers for the first time in the separation liquid. At this time, the density of the separation liquid is the first density.

[0026] It is understood that the terms "density," "second density," and "first density" in this application all characterize the physical properties of the quartz sand itself. Their magnitude is affected by impurities present in the quartz sand, such as metallic elements, and inclusions, but they differ from bulk density and generally do not change with particle size distribution indicators. The mass percentage of the first density refers to the ratio of the total weight of all quartz sand particles in the entire batch that satisfy the condition that the density of a single particle is less than or equal to the first density to the total weight of the entire batch of quartz sand.

[0027] For ease of understanding, let's label the first density as A. Then, the mass percentage of quartz sand particles with a density less than or equal to A is ≤4%. Let's label the second density as B. Then, 2.66 g / cm³... 3 >B≥2.63 g / cm 3At this point, because it is necessary to meet the requirements of the second density range and the mass ratio requirements of quartz sand particles within the first density range (i.e., less than or equal to the first density), quartz sand particles with excessively high or low density, such as impurities or inclusions, can be removed. As a result, the quartz sand as a whole exhibits fewer inclusion defects and fewer impurities, making it easier to meet the melting requirements of quartz crucibles.

[0028] For example, the mass percentage of quartz sand particles with a first density A less than or equal to that of the first density A can be, for example, 0%, 0.1%, 0.3%, 0.5%, 0.7%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, 3.5%, 3.6%, 3.8%, 4.0%, etc. The second density B can be, for example, 2.630 g / cm³. 3 2.632 g / cm 3 2.634 g / cm 3 2.635 g / cm 3 2.638 g / cm 3 2.640 g / cm 3 2.642 g / cm 3 2.645 g / cm 3 2.648 g / cm 3 2.650 g / cm 3 2.653 g / cm 3 2.654 g / cm 3 2.656 g / cm 3 2.658 g / cm 3 2.659 g / cm 3 wait.

[0029] In one specific embodiment, the mass percentage of the second density, the first density, and the quartz sand particles with a density less than or equal to the first density can be obtained by gravity separation measurement, which can be performed and evaluated using the following methods.

[0030] Weigh out a portion of a batch of quartz sand, for example, 5 kg, as the quartz sand to be evaluated. At a constant temperature of 20°C, add the quartz sand to be evaluated to 7.5 L of separation liquid (the separation liquid is tribromomethane) and stir for 5 minutes at a stirring speed of 20 r / min. After stirring, let it stand for 5 minutes.

[0031] If, after settling, all the quartz sand is at the bottom of the separating liquid or in a suspended state (that is, neither moving upwards nor downwards), then the entire batch of quartz sand is unqualified and no further operation is required.

[0032] After settling, when all the quartz sand is floating, ethanol is added to adjust the density of the separation solution; each adjustment is made by adding 0.002 g / cm³. 3 The addition of ethanol reduces the density; each adjustment requires stirring for 5 minutes at a speed of 20 rpm, followed by a 5-minute resting period after stirring. The movement trajectory of the quartz sand is observed during the adjustment process.

[0033] If the quartz sand exhibits a uniform suspension distribution, meaning that except for a few quartz sands that always float on the heavy liquid, it neither moves upward nor downward; in this case, the density of the separating liquid is the second density of the quartz sand.

[0034] If the quartz sand begins to separate into layers, meaning that the separation liquid that does not contain quartz sand is located between two layers of separation liquid that contain quartz sand, with a very small portion of the quartz sand floating on top and the majority of the quartz sand below the separation liquid, then the density of the separation liquid at this point is the first density.

[0035] After stratification, the quartz sand is divided into an upper layer and a lower layer. The quartz sand particles in the upper layer are separated and weighed. The mass ratio of the weight of the upper layer quartz sand particles to the total weight of all quartz sand to be evaluated is calculated. This mass ratio is the mass ratio of quartz sand particles with a density less than the first density. The quartz sand provided in this application can be a first type of quartz sand, a second type of quartz sand, or a third type of quartz sand.

[0036] In one optional embodiment, the quartz sand can be a first type of quartz sand, wherein the mass percentage of quartz sand with a particle size of 75~150μm is greater than or equal to 75%, for example, it can be 75%, 77%, 80%, 85%, 88%, 90%, 95%, 99%, 99.9%, etc.; the mass percentage of quartz sand with a particle size greater than 150μm is less than or equal to 5%, for example, it can be 5%, 4%, 3%, 2%, 1%, 0.1%, etc.; and the mass percentage of quartz sand with a particle size less than 75μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0037] Alternatively, the quartz sand can be a second type of quartz sand, wherein the mass percentage of quartz sand with a particle size of 150~212μm is greater than or equal to 40%, for example, it can be 40%, 50%, 55%, 60%, 65%, 70%, 80%, 99%, 99.9%, etc.; the mass percentage of quartz sand with a particle size greater than 212μm is less than or equal to 45%, for example, it can be 45%, 40%, 35%, 30%, 25%, 20%, 10%, 1%, 0.1%, etc.; and the mass percentage of quartz sand with a particle size less than 110μm is less than or equal to 12%, for example, it can be 12%, 11%, 10%, 8%, 6%, 5%, 3%, 1%, 0.1%, etc.

[0038] Alternatively, the quartz sand can be third-generation quartz sand, in which the mass percentage of quartz sand with a particle size of 150~212μm is greater than or equal to 35%, for example, it can be 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 99.9%, etc.; the mass percentage of quartz sand with a particle size greater than 212μm is less than or equal to 45%, for example, it can be 45%, 40%, 35%, 30%, 25%, 20%, 10%, 1%, 0.1%, etc.; and the mass percentage of quartz sand with a particle size less than 110μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0039] The first, second, and third quartz sands have different particle size distributions, which allows them to be applied in different implementation scenarios. For example, they can be used as quartz sand materials for different layers of a quartz crucible. Based on the characteristics and requirements of the bubble distribution from the inside to the outside of the quartz crucible, quartz sands with different particle size distributions can be used as quartz sand materials for different layers from the inside to the outside of the quartz crucible, thereby preparing a high-quality quartz crucible.

[0040] For example, the quartz crucible may include an inner layer, a middle layer, and an outer layer along a direction from the inside out, and the performance requirements of the quartz sand used in each layer increase from the outside to the inside. The first layer of quartz sand can be used as the inner layer, the second layer as the middle layer, and the third layer as the outer layer. This creates a gradual increase in the average particle size of the quartz sand from the inside to the outside during the quartz crucible melting process. This facilitates the removal of air bubbles from the inside to the outside using a vacuum method, thereby gradually reducing the bubble content of the prepared quartz crucible from the outside to the inside, thus improving the quality of the quartz crucible.

[0041] According to an embodiment of this application, optionally, the mass percentage of quartz sand particles with a density less than or equal to the first density in the above-mentioned quartz sand is no more than 1%.

[0042] This design helps to further reduce the impact of impurities and other defects in the quartz sand, and the quality of the quartz crucibles made from this quartz sand can be further improved, making it especially suitable for use as an inner layer quartz sand material and / or a middle layer quartz sand material.

[0043] For example, the mass percentage of quartz sand particles with a density less than or equal to the first density is greater than 1% and not greater than 2.5%, such as 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, etc. It is mainly suitable as a middle layer of quartz sand material, but is not limited to this. When used as an outer layer of quartz sand material, the melting effect of the quartz crucible is better.

[0044] For example, the mass percentage of quartz sand particles with a density less than or equal to the first density is no more than 0.5%, such as 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., which is mainly suitable as inner layer quartz sand material, but is not limited to this. When used as middle layer quartz sand material, the melting effect of quartz crucible is better.

[0045] Further optionally, in the above-mentioned quartz sand, the difference between the second density and the first density is greater than or equal to 0.001 g / cm³. 3 The difference here is mainly controlled by the precision of the separating liquid. If the difference is too small, it will be difficult to distinguish between the first density and the second density.

[0046] Alternatively, in the aforementioned quartz sand, the second density is greater than or equal to 2.63 g / cm³. 3 And less than or equal to 2.65 g / cm³ 3 For example, it could be 2.630 g / cm³ 3 2.632 g / cm 3 2.633 g / cm 3 2.634 g / cm 3 2.635 g / cm 3 2.637 g / cm 3 2.638 g / cm 3 0.639 g / cm 3 2.641 g / cm 3 2.643 g / cm 3 2.645 g / cm 3 2.647 g / cm 3 2.648 g / cm 3 2.650 g / cm 3 Such a method can meet the performance requirements of the outer layer of quartz sand in the quartz crucible, and the sorting cost is relatively low. Alternatively, the second density is greater than or equal to 2.64 g / cm³. 3 And less than or equal to 2.65 g / cm³ 3 This satisfies the performance requirements of the middle or outer layer of quartz sand in the quartz crucible. Alternatively, the second density must be greater than or equal to 2.65 g / cm³. 3 And less than 2.66 g / cm 3 This can satisfy the performance requirements of the inner, middle, or outer layer of quartz sand material in the quartz crucible.

[0047] According to embodiments of this application, the content of impurities or inclusions can be effectively controlled within a certain range through density distribution. However, a small amount of impurities that do not significantly affect the density distribution may still exist. Therefore, this application can further control the impurity content to meet the requirement of higher impurity content in the raw materials during the quartz crucible melting process. The quartz sand provided in this application has an impurity content of less than or equal to 25 ppm. Thus, when the impurity content of the quartz sand is not higher than 25 ppm, it is suitable as the outer layer quartz sand material of the quartz crucible, while when the impurity content is less than or equal to 20 ppm, it can be used as the inner, middle, and outer layer quartz sand material of the quartz crucible, and its performance will be even better.

[0048] According to embodiments of this application, the quartz sand provided is derived from natural quartz sand. Natural quartz sand possesses excellent structural strength and thermal stability, making it suitable as a raw material for quartz crucibles. Furthermore, natural quartz sand is abundant, and its mining and utilization costs are relatively low, helping to reduce costs while ensuring production is not affected by raw material shortages. Further, natural quartz sand with an α-quartz crystal form is preferred. α-quartz crystal form natural quartz sand has higher purity silica and a more stable crystal form, ensuring that crucibles prepared using it maintain chemical stability at high temperatures and reducing the impact of impurities on crucible quality.

[0049] According to another embodiment of this application, a blank for a quartz crucible is also provided, prepared from quartz sand as described above. Since the density distribution and sorting method of the quartz sand are the same as described above, they will not be repeated here.

[0050] The preparation method of the quartz crucible blank provided in the embodiments of this application may specifically include: sequentially arranging an outer layer of quartz sand, a middle layer of quartz sand, and an inner layer of quartz sand inside the crucible mold along an outside-to-inside direction to obtain the quartz crucible blank. The outer layer of quartz sand, the middle layer of quartz sand, and the inner layer of quartz sand are each prepared from the aforementioned quartz sand. The second density of the quartz sand in the outer layer of quartz sand is less than or equal to the second density of the quartz sand in the inner layer of quartz sand, thus satisfying the performance requirements of the middle and inner layers of quartz sand while having the advantage of lower cost.

[0051] According to embodiments of this application, optionally, the second density of the quartz sand in the middle layer is less than or equal to the second density of the quartz sand in the inner layer. For the same type of quartz sand, such as crystalline quartz sand, generally, higher density means lower inclusion content, which is beneficial for fusing a transparent layer with fewer inclusions and other defects and higher strength. By using quartz sand of different densities as different layers of quartz sand for the quartz crucible, it is beneficial to control the reduction of bubble content from the outside to the inside of the quartz crucible, thereby improving the quality of the quartz crucible.

[0052] For example, the secondary density of the quartz sand in the inner layer is greater than or equal to 2.65 g / cm³. 3 And less than 2.66 g / cm 3 ; and / or, the secondary density of the quartz sand in the intermediate layer is greater than or equal to 2.64 g / cm³. 3 And less than or equal to 2.65 g / cm³ 3 ; and / or, the secondary density of the outer layer of quartz sand is greater than or equal to 2.63 g / cm³. 3 And less than or equal to 2.65 g / cm³ 3 .

[0053] According to embodiments of this application, in the blank of the quartz crucible, the average particle size of the inner layer of quartz sand, the middle layer of quartz sand, and the outer layer of quartz sand increases sequentially. This arrangement is beneficial for crucible melting and simultaneously satisfies the requirement that the bubble content in different layers of the quartz crucible gradually increases from the inside to the outside.

[0054] According to an embodiment of this application, the crucible mold can be a rotary forming mold with any tilt angle. For example, it can be a graphite mold inserted into a metal water cooling jacket, and the outer layer of quartz sand, the middle layer of quartz sand and the inner layer of quartz sand are formed by hand in sequence using centrifugal force and forming rod to form a crucible shape and obtain a blank of quartz crucible.

[0055] According to the blank of the quartz crucible provided in the embodiments of this application, the quartz sand used may include at least one of the first quartz sand, the second quartz sand and the third quartz sand, wherein the particle size distribution of the first quartz sand, the second quartz sand and the third quartz sand is the same as described above, and will not be repeated here, thereby satisfying the requirements of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material for particle size distribution.

[0056] For ease of explanation, by way of example, the inner layer of quartz sand can use first quartz sand. And / or, the middle layer of quartz sand can use second quartz sand. And / or, the outer layer of quartz sand can use third quartz sand. The quartz sand material of this application can be flexibly applied to different layers of quartz sand in quartz crucibles, and the resulting quartz crucible has a high melting yield and exhibits a high single-crystal silicon pulling effect.

[0057] According to embodiments of this application, optionally, with the total mass of the quartz crucible blank as 100%, the mass percentage of the inner layer quartz sand is 10% to 30%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc.; the mass percentage of the middle layer quartz sand is 20% to 45%, for example, 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, etc.; and the mass percentage of the outer layer quartz sand is 35% to 50%, for example, 35%, 38%, 40%, 42%, 45%, 48%, 50%, etc. This configuration satisfies the performance requirements of each layer of the quartz crucible.

[0058] Furthermore, according to embodiments of this application, this application also provides a method for preparing a quartz crucible, comprising melting quartz sand containing the aforementioned material to obtain a quartz crucible. The quartz sand has an α-quartz crystal form, the mass percentage of quartz sand particles with a first density less than or equal to 4% is no greater than 4%, and the second density of the quartz sand is greater than or equal to 2.63 g / cm³. 3 And less than 2.66 g / cm 3 Since the density distribution and sorting methods of quartz sand are the same as those described above, they will not be repeated here.

[0059] More specifically, alternatively, melting is performed using quartz sand containing the aforementioned quartz sand to obtain a quartz crucible, which may specifically include operations S301 to S302:

[0060] In operation S301, along the direction from the outside to the inside, outer layer quartz sand, middle layer quartz sand and inner layer quartz sand are sequentially placed inside the crucible mold to obtain the blank of the quartz crucible. The average particle size of the inner layer quartz sand, middle layer quartz sand and outer layer quartz sand increases sequentially.

[0061] In operation S302, the blank of the quartz crucible is subjected to electric arc melting to obtain a quartz crucible, such that the quartz crucible includes an inner layer, a middle layer and an outer layer in a direction from the inside out, and the bubble content of the inner layer, the middle layer and the outer layer increases in sequence; wherein, at least one of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material includes the aforementioned quartz sand.

[0062] According to the embodiments of this application, since the quality of the quartz sand material is highly consistent after the density distribution is controlled, the bubble content from the inside to the outside of the quartz crucible can be controlled more effectively by the particle size distribution of the quartz sand.

[0063] According to the embodiments of this application, in operation S301, the setting of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material is the same as described above. The selection of the crucible mold and the selection of the blank forming method can be the same as described above, and will not be repeated here.

[0064] According to an embodiment of this application, in operation S302, the arc melting operation may include inserting an electrode into a pre-formed blank after arc initiation, causing it to rapidly melt into a crucible-shaped fused quartz. The arc melting operation is carried out under negative pressure, with air being drawn from the inner layer to the outer layer, thereby gradually increasing the bubble content from the inner layer to the outer layer, thus improving the quality of the quartz crucible.

[0065] According to another embodiment of this application, a quartz crucible prepared using the above-described quartz crucible blank, or a quartz crucible prepared using the above-described method, is provided. The quartz crucible provided by this application has high melting quality and exhibits good crystal pulling effect and service life.

[0066] According to another embodiment of this application, amorphous synthetic quartz sand is also provided, wherein the mass percentage of quartz sand particles with a first density less than or equal to 4% is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm³. 3 And less than 2.3 g / cm 3 .

[0067] Here, "amorphous synthetic quartz sand" refers to quartz sand obtained through artificial synthesis, where the quartz sand particles do not have a distinct crystalline structure, thus distinguishing it from crystalline quartz sand (such as natural quartz sand). It is understood that the "quartz sand" protected in this application refers to a batch of quartz sand used in the preparation of quartz crucibles, each batch potentially containing tens of kilograms, hundreds of kilograms, or several tons, each containing countless quartz sand particles.

[0068] The meanings of "second density" and "first density" are the same as those mentioned above, and the meaning of the mass percentage of quartz sand particles with a density less than or equal to the first density is the same as those mentioned above, and will not be repeated here.

[0069] For ease of understanding, let's label the first density as A, then the mass percentage of quartz sand particles with a density less than or equal to A is ≤4%, and let's label the second density as B, then B is greater than or equal to 2.2 g / cm³. 3 Less than 2.3 g / cm 3 At this point, because it is necessary to meet the requirements of the second density range and the mass ratio of quartz sand particles with a density less than or equal to the first density, quartz sand particles with excessively low density, such as those containing impurities or inclusions, can be removed. As a result, the quartz sand as a whole exhibits fewer gas-liquid inclusion defects and fewer impurities, making it easier to meet the melting requirements of quartz crucibles.

[0070] For example, the mass percentage of quartz sand particles with a first density A less than or equal to that of the first density A can be, for example, 0%, 0.1%, 0.3%, 0.5%, 0.7%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.3%, 2.5%, 2.8%, 3.0%, 3.2%, 3.4%, 3.5%, 3.6%, 3.8%, 4.0%, etc. The second density B can be, for example, 2.20 g / cm³. 3 2.21 g / cm 3 2.22 g / cm 3 2.23 g / cm 3 2.24 g / cm 3 2.25 g / cm 3 2.26 g / cm 3 2.27 g / cm 3 2.28 g / cm 3 2.29 g / cm 3 wait.

[0071] In one specific embodiment, the second density, the first density, and the mass percentage of quartz sand particles with a density less than or equal to the first density of amorphous synthetic quartz sand can be obtained by gravity separation measurement, specifically by the operation described above for crystalline quartz sand.

[0072] In one optional embodiment, the amorphous synthetic quartz sand can be a fourth type of quartz sand, wherein the mass percentage of quartz sand with a particle size of 75~150μm is greater than or equal to 75%, for example, it can be 75%, 77%, 80%, 85%, 88%, 90%, 95%, 99%, 99.9%, etc.; the mass percentage of quartz sand with a particle size greater than 150μm is less than or equal to 5%, for example, it can be 5%, 4%, 3%, 2%, 1%, 0.1%, etc.; and the mass percentage of quartz sand with a particle size less than 75μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0073] The fourth type of quartz sand can be used as the inner layer of quartz sand, and in combination with the second and third types, the second type can be used as the middle layer, and the third type can be used as the outer layer. This results in a gradual increase in the average particle size of the quartz sand from the inside to the outside of the crucible during the melting process. This facilitates the removal of air bubbles from the inside to the outside using a vacuum method, thereby reducing the bubble content of the prepared quartz crucible from the outside to the inside, thus improving the quality of the quartz crucible.

[0074] According to an embodiment of this application, optionally, the difference between the first density and the second density in the aforementioned quartz sand is greater than or equal to 0.001 g / cm³.3 The difference here is mainly controlled by the precision of the separating liquid. If the difference is too small, it will be difficult to distinguish between the first density and the second density.

[0075] According to embodiments of this application, the content of impurities or inclusions can be effectively controlled within a certain range by controlling the density distribution. However, a small amount of impurities that do not significantly affect the density distribution may still exist. Therefore, this application can further control the impurity content to meet the requirement for higher impurity content in the raw materials during the quartz crucible melting process. When the impurity content of the quartz sand provided in this application is less than or equal to 20 ppm, it can be used as the inner layer quartz sand material of the quartz crucible.

[0076] According to another embodiment of this application, a blank for a quartz crucible is also provided, which is prepared from amorphous synthetic quartz sand as described above. Since the density distribution and sorting method of the quartz sand are the same as described above, they will not be repeated here.

[0077] The preparation method of the quartz crucible blank provided in the embodiments of this application may specifically include: sequentially arranging an outer layer of quartz sand, a middle layer of quartz sand, and an inner layer of quartz sand inside the crucible mold along an outside-to-inside direction to obtain the quartz crucible blank. The inner layer of quartz sand is prepared from the aforementioned amorphous synthetic quartz sand. This satisfies the performance requirements of the inner layer of quartz sand.

[0078] According to embodiments of this application, in the blank of the quartz crucible, the average particle size of the inner layer of quartz sand, the middle layer of quartz sand, and the outer layer of quartz sand increases sequentially. This arrangement helps to meet the requirement that the bubble content in different layers of the quartz crucible gradually increases from the inside to the outside.

[0079] According to the blank of the quartz crucible provided in the embodiments of this application, the quartz sand used may contain a fourth type of quartz sand, which can be used in combination with at least one of the second and third types of quartz sand, thereby satisfying the requirements of the inner layer quartz sand, the middle layer quartz sand and the outer layer quartz sand for particle size distribution.

[0080] For ease of explanation, by way of example, the inner layer of quartz sand can use a fourth layer of quartz sand. The middle layer of quartz sand can use a second layer of quartz sand; and / or, the outer layer of quartz sand can use a third layer of quartz sand. The quartz sand material of this application can be flexibly applied to different layers of quartz sand in quartz crucibles, and the resulting quartz crucibles have a high melting yield and exhibit a high single-crystal silicon pulling effect.

[0081] According to embodiments of this application, optionally, with the total mass of the quartz crucible blank as 100%, the mass percentage of the inner layer quartz sand is 10% to 30%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc.; the mass percentage of the middle layer quartz sand is 20% to 45%, for example, 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, etc.; and the mass percentage of the outer layer quartz sand is 35% to 50%, for example, 35%, 38%, 40%, 42%, 45%, 48%, 50%, etc. This configuration satisfies the performance requirements of each layer of the quartz crucible.

[0082] Furthermore, according to embodiments of this application, this application also provides a method for preparing a quartz crucible, comprising melting amorphous synthetic quartz sand as described above to obtain a quartz crucible. The mass percentage of quartz sand particles with a first density less than or equal to 4% is no greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm³. 3 And less than 2.3 g / cm 3 Since the density distribution and sorting measurement methods of quartz sand, as well as the melting method of quartz crucibles, are the same as those described above, they will not be repeated here.

[0083] According to one embodiment of this application, a quartz crucible prepared using the above-described quartz crucible blank, or a quartz crucible prepared using the above-described method, is also provided. The quartz crucible provided by this application exhibits high melting quality, good crystal pulling effect, and long service life.

[0084] The present application is further illustrated below through embodiments and related test experiments and results. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present application. However, it is apparent that one or more embodiments may be implemented without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict.

[0085] It should be noted that the specific embodiments described below are merely illustrative examples, and the scope of protection of this application is not limited thereto. The chemicals and raw materials used in the following embodiments are all commercially available or prepared using recognized processing methods.

[0086] (1) Selection of quartz sand

[0087] Eight types of quartz sand were selected for testing, including:

[0088] Crystalline quartz sand 1: The secondary density of this crystalline quartz sand is 2.656 g / cm³. 3The first density is 2.644 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 0.48%.

[0089] Crystalline quartz sand 2: The secondary density of this crystalline quartz sand is 2.653 g / cm³. 3 The first density is 2.635 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 1%.

[0090] Crystalline quartz sand 3: The second density of this crystalline quartz sand is 2.648 g / cm³. 3 The first density is 2.638 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 1.45%.

[0091] Crystalline quartz sand 4: The second density of this crystalline quartz sand is 2.635 g / cm³. 3 The first density is 2.629 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 3.45%.

[0092] Crystalline quartz sand 5: The second density of this crystalline quartz sand is 2.621 g / cm³. 3 The first density is 2.613 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 8.00%.

[0093] Crystalline Quartz Sand 6: The secondary density of this crystalline quartz sand is 2.625 g / cm³. 3 The first density is 2.621 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 3%.

[0094] Crystalline Quartz Sand 7: The secondary density of this crystalline quartz sand is 2.635 g / cm³. 3 The first density is 2.619 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 10%.

[0095] Amorphous synthetic quartz sand 8: The secondary density of this amorphous synthetic quartz sand is 2.20 g / cm³. 3 The first density is 2.114 g / cm³. 3 The mass percentage of quartz sand particles with a density less than or equal to the first density is 3%.

[0096] (2) Preparation of quartz crucible blank

[0097] In a vacuum environment, following a direction from the outside in, the aforementioned crystalline quartz sand 1-7 and amorphous synthetic quartz sand 8 are prepared into inner layer quartz sand, middle layer quartz sand, and outer layer quartz sand according to actual needs. During the preparation of these materials, the particle sizes of the crystalline quartz sand 1-7 and amorphous synthetic quartz sand 8 meet the following requirements: the mass percentage of quartz sand particles with a diameter of 75~150μm in the inner layer quartz sand is greater than or equal to 75%, the mass percentage of quartz sand particles with a diameter greater than 150μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a diameter less than 75μm is less than 5%. The mass percentage of the particles in the middle layer of quartz sand is less than or equal to 15%; the mass percentage of quartz sand particles with a diameter of 75~150μm in the middle layer is greater than or equal to 75%, the mass percentage of quartz sand particles with a diameter greater than 150μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a diameter less than 75μm is less than or equal to 15%; the mass percentage of quartz sand particles with a diameter of 150~212μm in the outer layer is greater than or equal to 35%, the mass percentage of quartz sand particles with a diameter greater than 212μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a diameter less than 110μm is less than or equal to 15%.

[0098] Finally, the interior of the crucible mold is sequentially lined with an outer layer of quartz sand, a middle layer of quartz sand, and an inner layer of quartz sand to obtain a quartz crucible blank. The outer, middle, and inner layers of quartz sand constitute the total quartz sand, with the inner layer accounting for 20% of the total mass, the middle layer for 40%, and the outer layer for 40%. By placing the above eight different types of quartz sand in different proportions at different positions within the quartz blank, quartz blanks for Examples 1-6 and Comparative Examples 1-3, as shown in Table 1, were obtained.

[0099] (3) Preparation of quartz crucible

[0100] The blank of the quartz crucible is subjected to electric arc melting. Specifically, a vacuum operation is performed from the inside to the outside of the crucible mold to form a vacuum environment. After the electrode is arced, it is inserted into the formed blank and rapidly melted into molten quartz in the shape of a crucible, resulting in a quartz crucible with a transparent inner layer and an opaque outer layer.

[0101] (4) Measurement of the pass rate of quartz crucibles

[0102] Calculate the qualification rate of the quartz crucible according to requirements such as impurities and light transmittance. Specifically, use a magnifying glass to observe air bubbles, impurity points, white spots, etc. inside the quartz crucible; when the numbers of air bubbles, impurity points, white spots, etc. are within the standard limits respectively, it is qualified, otherwise it is unqualified. And record the wire breakage rate of using these batches of quartz crucibles during the single-crystal silicon crystal pulling process. The calculation method of the wire breakage rate is the total number of wire breaks from the start of crystal seeding to the end / the total number of crystal seeding times. The obtained melting qualification rate and wire breakage rate are shown in Table 1 below.

[0103] Table 1

[0104]

[0105] According to the results in Table 1, for the inner, middle, and outer quartz sand materials used in Example 1, when they all meet the density distribution requirements of the crystalline quartz sand in this application, the melting qualification rate reaches 97% and the wire breakage rate reaches 10%, indicating that based on the density distribution requirements of this application, the crystalline quartz sand can be controlled at a relatively high quality, which is beneficial to improving the quality of the prepared quartz crucible and showing a better melting qualification rate and crystal pulling effect.

[0106] The crystalline quartz sands selected through Examples 2 to 3 respectively meet the density distribution requirements of this application, but the quality of the crystalline quartz sand in the middle and outer quartz sand materials is lower than the second density in Example 1. Although compared with Example 1, the melting qualification rate and wire breakage rate in Examples 2 and 3 are slightly reduced, due to the use of the middle or outer quartz sand with a lower second density, the preparation cost of the quartz crucible will be lower. Therefore, if considering both the melting effect, crystal pulling effect and cost, Example 3 is the most preferred, and Example 2 is the second.

[0107] The crystalline quartz sands selected through Examples 4 to 5 respectively meet the density distribution requirements of this application, but the second density of the inner quartz sand material is less than that of the middle and / or outer quartz sand materials. It is found that at this time, both the melting qualification rate and the wire breakage rate deteriorate, especially the wire breakage rate increases significantly.

[0108] On the basis of Example 2, when Example 6 uses amorphous synthetic quartz sand instead of crystalline quartz sand as the inner quartz sand material, although the wire breakage rate of the melted quartz crucible increases slightly, the selected amorphous quartz sand according to this application can be used as the inner quartz sand material.

[0109] Through the comparison between Example 1 and Comparative Examples 1 to 3, it can be seen that when the density distribution requirements are not met, for example, in Comparative Example 1, the proportions of the second density and low-density quartz sand particles do not meet the requirements, in Comparative Example 2, the first density is too small, or in Comparative Example 3, the mass proportion of low-density quartz sand particles is too high, resulting in a relatively significant decrease in the melting qualification rate and it is completely unable to be used for the preparation of the crucible.

[0110] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above descriptions are merely specific embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A quartz sand having an a-quartz crystal form, a mass fraction of quartz sand particles equal to or less than a first density is not more than 4%, a second density of the quartz sand is equal to or more than 2.63 g / cm 3 and less than 2.66 g / cm 3 .

2. The quartz sand of claim 1, wherein, the difference between the second density and the first density is greater than or equal to 0.001 g / cm3 3 .

3. The quartz sand of claim 1, wherein, the second density is greater than or equal to 2.63 g / cm 3 and less than or equal to 2.65 g / cm 3 ; or, the second density is greater than or equal to 2.64 g / cm 3 and less than or equal to 2.65 g / cm 3 ; or, the second density is greater than or equal to 2.65 g / cm 3 and less than 2.66 g / cm 3 .

4. The quartz sand of claim 1, wherein, The mass percentage of quartz sand particles equal to or less than the first density is not more than 1%, or the mass percentage of quartz sand particles equal to or less than the first density is more than 1% and not more than 2.5%.

5. The quartz sand of claim 1, wherein, The mass percentage of quartz sand particles with a particle size of 75-150 μm is more than or equal to 75%, the mass percentage of quartz sand particles with a particle size of more than 150 μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a particle size of less than 75 μm is less than or equal to 15%; or the mass percentage of quartz sand particles with a particle size of 150-212 μm is more than or equal to 40%, the mass percentage of quartz sand particles with a particle size of more than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size of less than 110 μm is less than or equal to 12%; or the mass percentage of quartz sand particles with a particle size of 150-212 μm is more than or equal to 35%, the mass percentage of quartz sand particles with a particle size of more than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size of less than 110 μm is less than or equal to 15%.

6. The quartz sand of claim 1, wherein, The impurity content of the quartz sand is less than or equal to 25 ppm.

7. A body of a quartz crucible prepared from the quartz sand according to any one of claims 1 to 6.

8. The body of a quartz crucible according to claim 7, wherein, The body of the quartz crucible comprises, along a direction from inside to outside, an inner layer of quartz sand material, a middle layer of quartz sand material, and an outer layer of quartz sand material, respectively prepared from the quartz sand, wherein the second density of the quartz sand of the outer layer of quartz sand material is less than or equal to the second density of the quartz sand of the inner layer of quartz sand material.

9. The body of a quartz crucible according to claim 8, wherein, The second density of the quartz sand of the middle layer of quartz sand material is less than or equal to the second density of the quartz sand of the inner layer of quartz sand material.

10. The body of a quartz crucible according to claim 8, wherein, the second density of the quartz sand of the inner layer quartz sand charge is greater than or equal to 2.65 g / cm 3 and less than 2.66 g / cm 3 ; and / or, the second density of the quartz sand of the middle layer of quartz sand is greater than or equal to 2.64 g / cm 3 and less than or equal to 2.65 g / cm 3 ; and / or, The second density of the quartz sand of the outer layer quartz sand material is greater than or equal to 2.63 g / cm 3 and less than or equal to 2.65 g / cm 3 .

11. The body of a quartz crucible according to claim 8, wherein, The average particle size of the quartz sand of the inner layer of quartz sand material, the middle layer of quartz sand material, and the outer layer of quartz sand material increases in turn.

12. The body of a quartz crucible according to claim 11, wherein: The mass percentage of quartz sand particles with a particle size of 75-150 μm is more than or equal to 75%, the mass percentage of quartz sand particles with a particle size of more than 150 μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a particle size of less than 75 μm is less than or equal to 15%; and / or The mass percentage of quartz sand particles with a particle size of 150-212 μm is more than or equal to 40%, the mass percentage of quartz sand particles with a particle size of more than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size of less than 110 μm is less than or equal to 12%; and / or The mass percentage of quartz sand particles with a particle size of 150-212 μm is more than or equal to 35%, the mass percentage of quartz sand particles with a particle size of more than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size of less than 110 μm is less than or equal to 15%.

13. The body of a quartz crucible according to claim 8, wherein, The mass percentage of the inner layer of quartz sand material is 10%-30%, the mass percentage of the middle layer of quartz sand material is 20%-45%, and the mass percentage of the outer layer of quartz sand material is 35%-50%, based on the total mass of the body of the quartz crucible being 100%.

14. A quartz crucible prepared using the body of the quartz crucible according to any one of claims 7 to 13.

15. A method for preparing a quartz crucible, comprising: melting using quartz sand to obtain the quartz crucible; The quartz sand has an alpha-quartz crystal form, the mass proportion of quartz sand particles with a first density less than or equal to 4%, the second density of the quartz sand is greater than or equal to 2.63 g / cm 3 and less than 2.66 g / cm 3 .

16. A synthetic quartz sand that is amorphous, wherein a mass fraction of quartz sand particles having a first density of 2.2 g / cm3 or greater and less than 2.3 g / cm3 is not greater than 4%, and a second density of the quartz sand is 2.2 g / cm3 or greater. 3 3 .​ 17. The quartz sand of claim 16, wherein, a difference between the first density and the second density is greater than or equal to 0.001 g / cm3 3 .

18. The quartz sand of claim 16, wherein, the quartz sand having a mass percentage of quartz sand particles with a particle size of 75-150 μm of greater than or equal to 75%, a mass percentage of quartz sand particles with a particle size of greater than 150 μm of less than or equal to 5%, and a mass percentage of quartz sand particles with a particle size of less than 75 μm of less than or equal to 15%.

19. The quartz sand of claim 16, wherein, the quartz sand having an impurity content of less than or equal to 20 ppm.

20. A body of a quartz crucible prepared using the quartz sand according to any one of claims 16 to 19.

21. The body of a quartz crucible according to claim 20, wherein, the body of the quartz crucible comprising, in order from the inside out, an inner layer of quartz sand, a middle layer of quartz sand, and an outer layer of quartz sand, wherein the inner layer of quartz sand is selected from the quartz sand.

22. The body of a quartz crucible according to claim 21, wherein, the average particle size of the quartz sand of the inner layer of quartz sand, the middle layer of quartz sand, and the outer layer of quartz sand increases in order.

23. The body of a quartz crucible according to claim 22, wherein, the quartz sand of the inner layer of quartz sand has a mass percentage of quartz sand particles with a particle size of 75-150 μm of greater than or equal to 75%, a mass percentage of quartz sand particles with a particle size of 150-212 μm of less than or equal to 5%, and a mass percentage of quartz sand particles with a particle size of less than 75 μm of less than or equal to 15%; and / or the quartz sand of the middle layer of quartz sand has a mass percentage of quartz sand particles with a particle size of 150-212 μm of greater than or equal to 40%, a mass percentage of quartz sand particles with a particle size of greater than 212 μm of less than or equal to 45%, and a mass percentage of quartz sand particles with a particle size of less than 110 μm of less than or equal to 12%; and / or the quartz sand of the outer layer of quartz sand has a mass percentage of quartz sand particles with a particle size of 150-212 μm of greater than or equal to 35%, a mass percentage of quartz sand particles with a particle size of greater than 212 μm of less than or equal to 45%, and a mass percentage of quartz sand particles with a particle size of less than 110 μm of less than or equal to 15%.

24. The body of a quartz crucible according to claim 21, wherein, the inner layer of quartz sand has a mass percentage of 10-30%, the middle layer of quartz sand has a mass percentage of 20-45%, and the outer layer of quartz sand has a mass percentage of 35-50%, based on the total mass of the body of the quartz crucible.

25. A quartz crucible prepared using the body of the quartz crucible according to any one of claims 20 to 24.

26. A method for preparing a quartz crucible, comprising: melting using quartz sand to obtain the quartz crucible; The quartz sand is amorphous synthetic quartz sand, the mass proportion of quartz sand particles less than or equal to the first density is not more than 4%, the second density of the quartz sand is greater than or equal to 2.2 g / cm 3 and less than 2.3 g / cm 3 .

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