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

Abstract

The invention provides amorphous 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 mass ratio of the amorphous quartz sand particles larger than that of the quartz sand particles with the first density is not larger than 8%; the second density of the amorphous quartz sand is larger than or equal to 2.19 g / cm < 3 > and smaller than 2.24 g / cm < 3 >, and the mass ratio of the quartz sand particles equal to the second density is larger than 91%, preferably larger than 95%, and more preferably larger than 97%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quartz sand sorting and quartz crucible melting, in particular, the present application relates to an amorphous quartz sand, a quartz crucible and a body thereof, and a preparation method. BACKGROUND

[0002] After the single crystal silicon is drawn, the used quartz crucible is discarded to form waste quartz crucibles. The waste quartz crucibles are generally disposed of or landfilled, which not only affects the environment but also requires a certain cost. At present, there are documents disclosing a method and product for producing quartz sand and fused quartz sand from waste quartz crucibles. The quartz sand prepared from the waste quartz crucibles is mostly amorphous quartz sand. The cost of the amorphous quartz sand is low, but it is currently only used as a filler for metallurgical raw materials, porcelain and refractory materials, or construction machinery, and the benefit is small.

[0003] As a molten silicon container for pulling single crystal silicon, the quartz crucible is a key consumable in the crystal pulling process. High-purity quartz sand, as a raw material for producing the quartz crucible, is a key raw and auxiliary material, which determines the quality of the quartz crucible. The existing quartz crucible is mainly prepared from natural quartz sand, which is expensive, resulting in high preparation cost of the quartz crucible.

[0004] Therefore, if the amorphous quartz sand prepared from the waste quartz crucible can be applied to the preparation of the quartz crucible, it will have high value. However, no relevant reports have been found at present. SUMMARY

[0005] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present application provides an amorphous quartz sand, a quartz crucible and a body thereof, and a preparation method.

[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0007] According to an embodiment of the present application, an amorphous quartz sand is provided, the mass percentage of quartz sand particles with a first density is not more than 8%; the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm 3 and less than 2.24 g / cm 3 The mass percentage of quartz sand particles with the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0008] According to another embodiment of the present application, a body of a quartz crucible is provided, which comprises the amorphous quartz sand as described above.

[0009] According to still another embodiment of the present application, a quartz crucible is provided, which is prepared from the body of the quartz crucible as described above.

[0010] According to another embodiment of this application, a method for preparing a quartz crucible is provided, comprising: melting a quartz sand material containing amorphous quartz sand to obtain a quartz crucible; wherein the mass percentage of quartz sand particles with a density greater than a first density is not greater than 8%; and the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm³. 3 And less than 2.24 g / cm 3 The mass percentage of quartz sand particles of the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0011] According to the amorphous quartz sand provided in the embodiments of this application, by controlling its density distribution within the above-mentioned range, amorphous quartz sand particles containing impurities, inclusions and / or crystalline phases are removed. Thus, quartz crucibles that can be used for crystal pulling can be prepared using the above-mentioned amorphous quartz sand, effectively reducing the preparation cost of quartz crucibles. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments.

[0013] 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.

[0014] 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.

[0015] 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.).

[0016] In existing technologies for preparing quartz crucibles, the raw material is generally crystalline natural quartz sand. The selection criteria for crystalline natural quartz sand mainly focus on low impurity content and suitable particle size distribution. However, through extensive testing, the applicant has found that if the selection criteria for natural sand are used to select amorphous quartz sand, the yield of quartz crucibles produced is low. Therefore, the selection criteria for amorphous quartz sand cannot be applied to those for natural sand.

[0017] The inventors of this application have discovered that the amorphous quartz sand prepared from waste quartz crucibles contains amorphous quartz sand encapsulated with air bubbles, impurities, and / or crystalline phases. The presence of these sand particles is the primary cause of defects in the prepared quartz crucibles.

[0018] Further research by the applicant revealed that by controlling indicators such as the second density and the mass percentage of quartz sand particles with a density greater than the first density, amorphous quartz sand can be precisely controlled to maintain a high quality with good consistency. Quartz crucibles melted using amorphous quartz sand that meets this density distribution exhibit consistently high quality.

[0019] Specifically, according to one embodiment of this application, an amorphous quartz sand is provided, wherein the mass percentage of quartz sand particles with a density greater than a first density is no more than 8%; the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm³. 3 And less than 2.24 g / cm 3 The mass percentage of quartz sand particles of the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0020] In this application, "amorphous quartz sand" refers to quartz sand particles that do not have a distinct crystal structure, thus distinguishing them from crystalline quartz sand (such as natural quartz sand). It is produced by processing waste quartz crucibles. A batch of amorphous quartz sand prepared from waste quartz crucibles may contain countless amorphous quartz sand particles (or simply quartz sand particles), ranging from tens of kilograms to hundreds of kilograms or even several tons.

[0021] In this application, "first density" refers to the density of the separation solution used in the gravity separation of quartz sand. First, the separation solution is used to make all the quartz sand float. Then, ethanol is used to reduce the density of the separation solution in turn. When the quartz sand in the separation solution begins to separate into layers, most of the quartz sand floats and a very small part of the quartz sand is in the lower layer, the density of the separation solution at this time is the first density.

[0022] In this application, the "second density" refers to the process of removing a very small portion of the quartz sand from the lower layer, and then continuing to use ethanol to gradually reduce the density of the separation liquid. This results in most of the quartz sand being in a suspended state, except for a small amount that always floats on the surface of the separation liquid. The density of the separation liquid at this point can be considered as the second density of the quartz sand.

[0023] For ease of understanding, the first density is labeled A, and the second density is labeled B, 2.19 g / cm³. 3 ≤B<2.24g / cm 3 Furthermore, the mass percentage of quartz sand particles larger than A is no more than 8%. Because the requirements for the second density and the proportion of quartz sand particles, as well as the proportion of quartz sand particles with a density greater than the first density, need to be met, quartz sand particles with high density and encapsulated impurities or crystalline phases in amorphous quartz sand can be removed. Therefore, amorphous quartz sand as a whole exhibits fewer impurities or crystalline phase defects, making it easier to meet the melting requirements of quartz crucibles.

[0024] For example, the second density B can be, for instance, 2.190 g / cm³. 3 2.195 g / cm 3 2.200 g / cm 3 2.205 g / cm 3 2.210 g / cm 3 2.215 g / cm 3 2.220 g / cm 3 2.221 g / cm 3 2.222 g / cm 3 2.224 g / cm 3 2.225g / cm 3 2.228 g / cm 3 2.230 g / cm 3 2.235 g / cm 3 2.238 g / cm 3 2.239 g / cm 3 The mass percentage of quartz sand particles with a density equal to the second density B is greater than 91%, for example, it could be 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc. The mass percentage of quartz sand particles with a density greater than the first density can be, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc.

[0025] It is understood that the "density", "second density" and "first density" in this application all characterize the physical properties of amorphous quartz sand itself. Their values ​​are affected by the density of all quartz sand particles in amorphous quartz sand, but they are different from bulk density and do not change with the particle size distribution index.

[0026] The mass percentage greater than the first density A refers to the ratio of the total weight of all amorphous quartz sand particles in the entire batch that meet the condition that the density of a single amorphous quartz sand particle is greater than the first density A, to the total weight of the entire batch of amorphous quartz sand.

[0027] According to an embodiment of this application, optionally, in the above-mentioned amorphous quartz sand, the difference between the second density B and the first density A is greater than or equal to 0.001 g / cm³. 3 And less than 0.3 g / cm 3 That is, A and B satisfy the relationship: Δρ1=AB, and 0.001 g / cm³ 3 ≤△ρ1<0.3g / cm 3 For example, the difference Δρ1 could be, for instance, 0.001 g / cm³. 3 0.002 g / cm 3 0.005 g / cm 3 0.008 g / cm 3 0.01 g / cm 3 0.02 g / cm 3 0.05g / cm 3 0.08 g / cm 3 0.1 g / cm 3 0.15 g / cm 3 0.18 g / cm 3 0.2 g / cm 3 0.23 g / cm 3 0.25 g / cm 3 0.28 g / cm 3 0.29 g / cm 3 wait.

[0028] The magnitude of this difference is determined on the one hand by the amorphous quartz sand to be separated. A large difference indicates that while relatively consistent quartz sand can be separated, there is still significant room for quality improvement. On the other hand, during heavy liquid separation measurements, the density range of the separating solution is affected by the addition of ethanol each time. A smaller difference requires higher precision in density control of the separating solution and increases the difficulty of stratification. By controlling the difference within the aforementioned range, it is beneficial to further reduce the impact of impurities and crystalline phases trapped in the quartz sand, thereby further improving the quality of the quartz crucibles made using this quartz sand.

[0029] According to an embodiment of this application, optionally, the mass percentage of amorphous quartz sand particles with a density less than the third density in this application is no more than 1%.

[0030] In this application, the "third density" refers to the density of the separation liquid further reduced by ethanol after the quartz sand and separation liquid have reached their second density. After the addition is complete and the mixture is allowed to stand, the quartz sand in the separation liquid stratifies again, and the density of the separation liquid at this point is the third density. Similarly, the third density characterizes the physical properties of amorphous quartz sand itself, and is distinct from bulk density, and does not change with changes in particle size distribution.

[0031] The mass percentage of quartz sand particles with a density less than the third density refers to the ratio of the total weight of all amorphous quartz sand particles in the entire batch that meet the condition that the density of a single amorphous quartz sand particle is less than the third density to the total weight of the entire batch of amorphous quartz sand.

[0032] For ease of understanding, the third density is denoted as C, and the mass percentage of quartz sand particles with a density less than C is no more than 1%. Since the amorphous quartz sand in this application also meets the requirement of a proportion of quartz sand particles with a density less than the third density, low-density quartz sand particles, such as those containing air bubbles, can be removed. Therefore, the amorphous quartz sand as a whole exhibits fewer defects such as air bubbles, making it easier to meet the melting requirements of quartz crucibles. For example, the mass percentage of quartz sand particles with a density less than the third density C can be, for example, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0033] In one specific embodiment, the mass percentages of the first density, second density, third density, and quartz sand particles with a density greater than the first density, the mass percentages of quartz sand particles with a density equal to the second density, and the mass percentages of quartz sand particles with a density less than the third density can be obtained by heavy liquid separation measurement. Specifically, the following operations can be used for measurement and evaluation.

[0034] 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 sorting liquid (the sorting liquid is tribromomethane with 3 wt% ethanol stabilizer added, and the density of heavy liquid tribromomethane is 2.8804 g / ml at a constant temperature of 20°C) and stir for 5 minutes at a stirring speed of 20 r / min. After stirring, let it stand for 5 minutes.

[0035] 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.

[0036] After settling, if all the quartz sand floats, add ethanol to adjust the density of the separation solution; each adjustment involves 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.

[0037] When 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 most of the quartz sand floating on top and a very small portion of the quartz sand below the separation liquid, then the density of the separation liquid at this point is the first density.

[0038] The lower layer of quartz sand, which is a small portion of the stratified material below the separating liquid, is separated and weighed. Then, the mass ratio of the weight of the lower layer of quartz sand particles to the total weight of the batch of crystalline quartz sand is calculated. This mass ratio is the mass ratio of quartz sand particles with a density greater than the first density.

[0039] After separation, ethanol was added again to adjust the density of the separation solution; each adjustment was 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.

[0040] When the quartz sand exhibits a uniform suspension distribution, meaning that except for a very small number of sand particles floating on the separating liquid, it neither moves upwards nor downwards, then the density of the separating liquid at this point is the second density of the quartz sand.

[0041] Continue adding ethanol to adjust the density of the separation solution; each adjustment involves adding 0.002 g / cm³. 3The 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.

[0042] When the quartz sand begins to separate again, that is, the separation liquid that does not contain quartz sand is between two layers of separation liquid that contain quartz sand, a very small portion of the quartz sand is floating on the surface, and most of the quartz sand is below the separation liquid, then the density of the separation liquid at this time is the third density.

[0043] After stratification, the quartz sand is further divided into upper and lower layers. The quartz sand particles in the lower layer are separated and weighed. The mass ratio of the lower layer's quartz sand particles to the total weight of all quartz sand to be evaluated is calculated. This mass ratio is equal to the mass ratio of quartz sand particles with the second density. The quartz sand particles in the upper layer are separated and weighed. The mass ratio of the upper layer's quartz sand particles to the total weight of all quartz sand to be evaluated is calculated. This mass ratio is less than the mass ratio of quartz sand particles with the third density.

[0044] According to an embodiment of this application, optionally, the difference between the third density C and the second density B is greater than or equal to 0.001 g / cm³. 3 Furthermore, it is preferred to have a concentration of less than 0.1 g / cm³. 3 That is, B and C satisfy the relationship: Δρ² = BC, and 0.001 g / cm³ 3 ≤△ρ2<0.1g / cm 3 For example, the difference Δρ2 could be, for instance, 0.001 g / cm³. 3 0.002 g / cm 3 0.004 g / cm 3 0.006 g / cm 3 0.008 g / cm 3 0.01 g / cm 3 0.02 g / cm 3 0.03 g / cm 3 0.04 g / cm 3 0.05 g / cm 3 0.06 g / cm 3 0.07 g / cm 3 0.08 g / cm 3 0.09 g / cm 3 Etc. Preferably, the difference Δρ2 is greater than or equal to 0.001 g / cm³. 3 And less than 0.01 g / cm 3By controlling the difference within the above range, it is beneficial to further reduce the impact of defects such as air bubbles trapped in the quartz sand, and the quality of the quartz crucibles melted using this quartz sand can be further improved.

[0045] According to embodiments of this application, the content of impurities, inclusions, and / or crystalline phases 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 higher impurity content requirements of the raw materials during the quartz crucible melting process. The impurity content of the amorphous quartz sand provided in this application can be less than or equal to 30 ppm. Along the inside-out direction, the quartz crucible can include an inner layer, a middle layer, and an outer layer, and the performance requirements for the quartz sand used in each layer increase from the outside to the inside. Thus, when the impurity content of the amorphous quartz sand is not higher than 30 ppm, it is suitable as the outer layer sand material of the quartz crucible, while when the impurity content is less than or equal to 20 ppm, it performs better as the middle and outer layer sand materials of the quartz crucible.

[0046] According to the embodiments of this application, the amorphous quartz sand of this application can be a first amorphous quartz sand, a second amorphous quartz sand, or a third amorphous quartz sand, wherein the first amorphous quartz sand, the second amorphous quartz sand, and the third amorphous quartz sand have different particle size distributions, so that they can be applied in different implementation scenarios, such as as quartz sand materials for different layers of a quartz melting crucible.

[0047] In one optional embodiment, the amorphous quartz sand can be a first amorphous quartz sand, wherein the mass percentage of quartz sand particles with a particle size of less than 175 μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.; and the mass percentage of quartz sand particles with a particle size of 175 μm-250 μm is greater than or equal to 75%, for example, it can be 78%, 80%, 85%, 90%, 95%, 99%, etc.

[0048] Alternatively, the amorphous quartz sand can be a second amorphous quartz sand, in which the mass percentage of quartz sand particles with a particle size of 250μm~325μm is greater than or equal to 37%, for example, it can be 40%, 43%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 100%, etc.; and the mass percentage of quartz sand particles with a particle size of 325μm-425μm is less than or equal to 63%, for example, it can be 60%, 57%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 0%, etc.

[0049] Alternatively, the amorphous quartz sand can be a third amorphous quartz sand, in which the mass percentage of quartz sand particles with a particle size of 250μm~330μm is greater than or equal to 37%, for example, it can be 40%, 43%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 100%, etc., and the mass percentage of quartz sand particles with a particle size of 330μm-430μm is less than or equal to 63%, for example, it can be 60%, 57%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 0%, etc.

[0050] According to the embodiments of this application, it can be understood that, under the condition of having the same density distribution, using amorphous quartz sand with different particle size distributions as quartz sand materials with different layers from the inside to the outside of the quartz crucible can reduce costs while taking into account the quality of the quartz crucible obtained by melting.

[0051] According to embodiments of this application, the first amorphous quartz sand can be used as the inner or middle layer of quartz sand, the second amorphous quartz sand can be used as the middle or outer layer of quartz sand, and the third amorphous quartz sand can be used as the outer layer of quartz sand. Thus, during the melting of the quartz crucible, a trend emerges where the average particle size of the amorphous quartz sand gradually increases from the inside to the outside of the crucible. 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, and improving the yield rate of the prepared quartz crucible.

[0052] According to an embodiment of this application, further, in the amorphous quartz sand, the mass percentage of quartz sand particles with a density greater than the first density is no more than 5%. This setting helps to further reduce the influence of amorphous quartz sand particles that encapsulate impurities or crystalline phases, and the quality of the quartz crucible melted using this amorphous quartz sand can be further improved, especially making it more suitable for use as an inner layer quartz sand material and / or a middle layer quartz sand material.

[0053] According to embodiments of this application, the amorphous quartz sand provided is derived from recycled waste quartz crucibles. For example, it can be obtained by crushing, screening, and high-temperature calcining the waste quartz crucibles. This is because, on the one hand, the production cost and process difficulty of preparing amorphous quartz sand from waste quartz crucible pieces are lower than those of artificially synthesized amorphous quartz sand; on the other hand, the process of artificially synthesizing amorphous quartz sand is cumbersome and easily introduces many fine air bubbles. Therefore, preparing amorphous quartz sand from waste quartz crucible pieces still has a significant advantage over artificially synthesized amorphous quartz sand.

[0054] To further meet the raw material requirements for quartz crucible preparation, the sorted amorphous quartz sand can be further sorted by particle size to obtain amorphous quartz sand with different particle size distributions, such as the first, second, and third amorphous quartz sands mentioned above. The specific particle size distributions are the same as described earlier and will not be repeated here. Particle size sorting methods can include operations such as grinding and grading. Grinding can be achieved by using at least one device such as a ball mill, jaw crusher, or roller crusher to refine the quartz sand particles into the desired particle size range. Grading can be achieved by selecting sieves of different mesh sizes to separate the ground quartz sand into different particle size ranges, or by using a centrifugal sieve to separate the ground quartz sand into different particle size ranges.

[0055] The amorphous quartz sand with the aforementioned density distribution can be used to prepare the blank of a quartz crucible, so as to obtain a high-quality quartz crucible through melting. Specifically, another embodiment of this application also provides a blank of a quartz crucible prepared from quartz sand material containing the amorphous quartz sand described above. Since the density distribution of amorphous quartz sand and the heavy liquid separation measurement method are the same as described above, they will not be repeated here.

[0056] According to the embodiments of this application, the aforementioned amorphous quartz sand is used as a raw material to make a blank for a quartz crucible, thereby melting the quartz crucible. Since it exhibits higher purity and fewer defects overall, it reduces the adverse effects of amorphous quartz sand containing impurities, crystalline phases, and bubbles during the melting process. This is beneficial for obtaining a quartz crucible, and thus enables the amorphous quartz sand prepared from waste quartz crucibles to replace expensive natural quartz sand in the preparation of quartz crucibles.

[0057] According to embodiments of this application, in order to further improve the melting quality of the quartz crucible, the mass percentage of amorphous quartz sand in the quartz crucible blank is preferably 10% to 30%, for example, 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc. If the mass percentage is too high, the yield of the melted quartz crucible will be low; if the mass percentage is too low, it will be difficult to balance process cost and melting quality.

[0058] For example, taking a quartz crucible comprising an inner layer, a middle layer, and an outer layer along an inside-out direction, the blank of the quartz crucible comprises an inner layer, a middle layer, and an outer layer along an inside-out direction. The amorphous quartz sand provided in this application can be quartz sand material used for at least one of the inner layer, the middle layer, and the outer layer, and can be natural quartz sand used to replace or at least partially replace at least one of the inner layer, the middle layer, and the outer layer.

[0059] The preparation method of the quartz crucible blank provided in the embodiments of this application may specifically include: sequentially setting an outer layer, a middle layer, and an inner layer of quartz sand material inside the crucible mold along a direction from the outside to the inside, thereby obtaining the quartz crucible blank. The average particle size of the quartz sand material in the inner layer, the middle layer, and the outer layer increases sequentially.

[0060] 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 by centrifugal force and forming rod to form a crucible shape and obtain a blank of quartz crucible.

[0061] According to the blank of the quartz crucible provided in the embodiments of this application, the amorphous quartz sand used may include at least one of the first amorphous quartz sand, the second amorphous quartz sand and the third amorphous quartz sand, wherein the particle size distribution of the first amorphous quartz sand, the second amorphous quartz sand and the third amorphous 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.

[0062] For ease of explanation, exemplarily, the inner layer of quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the inner layer is defined as first amorphous quartz sand. And / or, the middle layer of quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the middle layer is defined as first amorphous quartz sand or second amorphous quartz sand. And / or, the outer layer of quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the outer layer is defined as third amorphous quartz sand. In other words, first amorphous quartz sand can be used in the inner or middle layer of quartz sand, second amorphous quartz sand can be used in the middle or outer layer of quartz sand, and third amorphous quartz sand can be used in the outer layer of quartz sand. The amorphous 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.

[0063] According to embodiments of this application, optionally, with the total mass of the quartz crucible blank as 100%, the mass percentage of quartz sand in the inner layer is 10% to 30%, for example, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc.; the mass percentage of quartz sand in the middle layer is 20% to 45%, for example, 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, etc.; and the mass percentage of quartz sand in the outer layer 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.

[0064] According to another embodiment of this application, a quartz crucible prepared using the above-described quartz crucible blank is provided.

[0065] This application also provides a method for preparing a quartz crucible, comprising melting a quartz sand material containing amorphous quartz sand to obtain a quartz crucible, wherein the mass percentage of quartz sand particles with a density greater than a first density is not greater than 8%; and the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm³. 3 And less than 2.24 g / cm 3 The mass percentage of quartz sand particles with the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%. Since the density distribution and heavy liquid separation measurement methods for amorphous quartz sand are the same as those described above, they will not be repeated here.

[0066] More specifically, alternatively, the quartz crucible may be obtained by melting quartz sand containing amorphous quartz sand, which may specifically include operations S301 to S302.

[0067] Operation S301: Along the direction from the outside to the inside, quartz sand is used to sequentially set the outer layer, middle layer and inner layer inside the crucible mold to obtain the blank of the quartz crucible. The average particle size of the quartz sand in the inner layer, the middle layer and the outer layer increases sequentially.

[0068] 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 the direction from the inside to the outside, and the bubble content of the inner layer, the middle layer and the outer layer increases in sequence; wherein, at least one of the quartz sand material in the inner layer, the quartz sand material in the middle layer and the quartz sand material in the outer layer includes amorphous quartz sand.

[0069] Based on the amorphous quartz sand provided in this application, the quality of the amorphous quartz sand has a high degree of consistency after the density distribution is controlled. This means that in the preparation process of quartz crucibles, the bubble content of the quartz crucibles can be effectively avoided, or impurities, white spots, etc. can be generated, which would prevent the preparation of quartz crucibles.

[0070] According to the embodiments of this application, in operation S301, the inner layer, middle layer and outer layer are set up in the same way as described above. The selection of crucible mold and the selection of blank forming method can be the same as the preparation method of the blank of the quartz crucible described above, and will not be repeated here.

[0071] 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 performed under vacuum conditions, with vacuuming proceeding 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.

[0072] 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.

[0073] 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.

[0074] (1) Selection of quartz sand

[0075] Eight types of amorphous quartz sand were selected for testing, including:

[0076] Quartz sand 1: The primary density of this quartz sand is 2.2208 g / cm³. 3 The second density is 2.2187 g / cm³. 3 Greater than 2.2208 g / cm³ 3 The mass percentage of quartz sand particles is 4%, which is equal to the mass percentage of quartz sand particles with the second highest density of 95%. The mass percentage of particles with a diameter of 250μm to 330μm is 40%, and the mass percentage of particles with a diameter of 330μm to 430μm is 60%.

[0077] Quartz sand 2: The primary density of this quartz sand is 2.2206 g / cm³. 3 The second density is 2.2186 g / cm³.3 The third density is 2.2066 g / cm³. 3 ≥2.2206 g / cm³ 3 The mass percentage of quartz sand particles is 1.0%, which is less than 2.2066 g / cm³. 3 The mass percentage of quartz sand particles is 0.50%, which is equal to the mass percentage of quartz sand particles with the second density of 98.5%. The mass percentage of particles with a diameter of 250μm~330μm is 40%, and the mass percentage of particles with a diameter of 330μm~430μm is 60%.

[0078] Quartz sand 3: The primary density of this quartz sand is 2.2204 g / cm³. 3 The second density is 2.2186 g / cm³. 3 The third density is 2.2053 g / cm³. 3 ≥2.2204 g / cm³ 3 The mass ratio of quartz sand particles is 1.2%, which is less than 2.2053 g / cm³. 3 The mass percentage of quartz sand particles is 0.8%, which equals the mass percentage of quartz sand particles with the second highest density of 98.00%. The proportion of quartz sand with a particle size of 250μm~330μm is 8%, and the proportion of quartz sand with a particle size of 330μm~430μm is 92%.

[0079] Quartz sand 4: The primary density of quartz sand is 2.22 g / cm³. 3 The second density is 2.2188 g / cm³. 3 The third density is 2.2089 g / cm³. 3 ≥2.22 g / cm 3 The mass percentage of quartz sand particles is 0.9%, which is less than 2.2089 g / cm³. 3 The mass percentage of quartz sand particles is 0.4%, which is equal to the mass percentage of quartz sand particles with the second highest density of 98.7%. The mass percentage of quartz sand particles with a particle size of 250μm~325μm is 45%, and the mass percentage of quartz sand particles with a particle size of 330μm~430μm is 55%.

[0080] Quartz sand 5: The primary density of quartz sand is 2.221 g / cm³. 3 The second density is 2.219 g / cm³. 3 The third density is 2.2076 g / cm³. 3 ≥2.221 g / cm³ 3 The mass percentage of quartz sand particles is 1.3%, which is less than 2.2076 g / cm³. 3The mass percentage of quartz sand particles is 0.7%, and the mass percentage of quartz sand particles with the second highest density is 98.00%. The mass percentage of quartz sand with a particle size less than 175μm is 10%, and the mass percentage of quartz sand with a particle size of 175μm-250μm is 90%.

[0081] Quartz Sand 6: The primary density of quartz sand is 2.4522 g / cm³. 3 The second density is 2.1024 g / cm³. 3 ≥2.4522 g / cm³ 3 The mass percentage of quartz sand particles is 15%; the mass percentage of quartz sand particles with the second highest density is 85.00%. The proportion of quartz sand with a particle size of 250μm~330μm is 44%, and the proportion of quartz sand with a particle size of 330μm~430μm is 56%.

[0082] Quartz Sand 7: The primary density of quartz sand is 2.5406 g / cm³. 3 The second density is 2.2246 g / cm³. 3 ≥2.5406 g / cm³ 3 The mass percentage of quartz sand particles is 13%, which equals the mass percentage of quartz sand particles with the second highest density of 87.00%. Quartz sand with a particle size of 250μm~330μm accounts for 41%, and quartz sand with a particle size of 330μm~430μm accounts for 59%.

[0083] Quartz Sand 8: The primary density of quartz sand is 2.5022 g / cm³. 3 The second density is 2.3024 g / cm³. 3 ≥2.5022 g / cm³ 3 The mass percentage of quartz sand particles is 14%, which equals the mass percentage of quartz sand particles with the second highest density of 86.00%. Quartz sand with a particle size of 250μm~330μm accounts for 43%, and quartz sand with a particle size of 330μm~430μm accounts for 57%.

[0084] Two types of quartz sand were selected and sorted from commercially available high-purity natural crystalline quartz sand (produced by Unimin, with SiO2 purity greater than 99.998% and impurity content less than 20 ppma). Among them:

[0085] Quartz Sand 9: The mass percentage of quartz sand with a particle size of less than 175μm is less than or equal to 15%, and the mass percentage of quartz sand with a particle size of 175μm-250μm is greater than or equal to 75%.

[0086] Quartz sand 10: The mass ratio of quartz sand with a particle size of 250 μm to 325 μm is greater than or equal to 37%, and the mass ratio of quartz sand with a particle size of 325 μm - 425 μm is less than or equal to 63%.

[0087] (2)Preparation of quartz crucible blank

[0088] Along the direction from outside to inside, in a vacuum environment, an outer layer, a middle layer and an inner layer are sequentially arranged inside the crucible mold to obtain the blank of the quartz crucible.

[0089] The quartz sand materials of the outer layer, the middle layer and the inner layer constitute the total quartz sand material. The mass ratio of the quartz sand material of the inner layer to the total quartz sand material is 20%, the mass ratio of the quartz sand material of the middle layer to the total quartz sand material is 40%, and the mass ratio of the quartz sand material of the outer layer to the total quartz sand material is 40%. The quartz sand materials of the outer layer, the middle layer and the inner layer are prepared from natural quartz sand and / or amorphous quartz sand according to their respective conditions. In this application, the above 8 different amorphous quartz sands and 2 natural quartz sands are arranged at different positions of the quartz blank in different proportions, and Examples 1 - 6 and Comparative Examples 1 - 3 shown in Table 1 below are set.

[0090] (3)Preparation of quartz crucible

[0091] The blank of the quartz crucible is subjected to arc melting. Specifically, the crucible mold is evacuated from inside to outside to form a vacuum environment, and after the electrode is arced, it is inserted into the formed blank to quickly melt it into molten quartz in the shape of a crucible, so that the bubble content of the inner layer, the middle layer and the outer layer of the quartz crucible increases in turn, and a high-quality quartz crucible with a transparent inner layer and an opaque outer layer is obtained.

[0092] (4)Measurement of the qualification rate of quartz crucible

[0093] The qualification rate of the quartz crucible is calculated according to the requirements for impurities and light transmittance, etc. The test method and test standard for the qualification rate are to observe the bubbles, impurity points and white spots inside the quartz crucible with a magnifying glass. If the number of bubbles, impurity points and white spots is within the standard limit, it is qualified, otherwise it is unqualified. The data of the melting qualification rate of the crucible are shown in Table 1.

[0094] Table 1 Composition of quartz blanks and data of crucible melting qualification rate in Examples 1 - 6 and Comparative Examples 1 - 3

[0095] Total ratio of inner layer sand Ratios of various inner layer sands Total ratio of middle layer sand Ratios of various middle layer sands Total ratio of outer layer sand Ratios of various outer layer sands Crucible melting pass rate Example 1 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 1 (18%) 60% Example 2 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 2 (18%) 95% Example 3 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 3 (18%) 70% Example 4 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 2 (40%) 55% Example 5 20% Quartz sand 9 (20%) 40% Quartz sand 10 (22%) + quartz sand 4 (18%) 40% Quartz sand 10 (22%) + quartz sand 2 (18%) 40% Example 6 20% Quartz sand 9 (22%) + quartz sand 5 (18%) 40% Quartz sand 10 (22%) + quartz sand 4 (18%) 40% Quartz sand 10 (22%) + quartz sand 2 (18%) 20% Comparative Example 1 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 6 (18%) 0% Comparative Example 2 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 7 (18%) 0% Comparative Example 3 20% Quartz sand 9 (20%) 40% Quartz sand 10 (40%) 40% Quartz sand 10 (22%) + quartz sand 8 (18%) 0%

[0096] Table 1 shows the composition of the quartz blanks and the crucible melting qualification rate data of Examples 1-6 and Comparative Examples 1-3. As can be seen from Table 1, (1) in Example 1, the outer layer of quartz sand material uses amorphous quartz sand that meets the density distribution requirements of this application, and the crucible melting qualification rate can reach 60%. In Examples 2-3, after further optimizing the quality of amorphous quartz sand, the melting qualification rate can be further improved to 70%-95%. In particular, the melting qualification rate of Example 2 can even be better than the melting qualification rate of 93%-94% when all natural quartz sand is used. (2) By comparing Examples 1-2 and Comparative Examples 1-3, it can be seen that when the predetermined density range is not met, for example, in Comparative Example 1, the second density is too small and the proportion of quartz sand particles larger than the first density is too large; in Comparative Example 2, the proportion of quartz sand particles larger than the first density is too large and the difference between the first density and the second density is too large; in Comparative Example 3, the mass proportion of quartz sand particles larger than the first density is too high, all of which make it difficult to control the quality of amorphous quartz sand, ultimately leading to the failure of crucible melting. (3) The particle size distribution of the amorphous quartz sand selected in Example 3 is not within the range of amorphous quartz sand. Although the quartz crucible can be successfully melted, the melting qualification rate drops from 93% to 70% compared to Example 1. It is speculated that this is because the particle size distribution range affects the bubble content in the crucible. If the bubble content is too high, the qualification rate will easily decrease. (4) In Examples 4 and 5, amorphous quartz sand was used in the inner and middle layers of quartz sand. Although quartz crucibles could be successfully melted, the pass rate was reduced. It can be seen that the initially sorted quartz sand is still difficult to meet the high performance requirements of the inner and middle layers of quartz sand.

[0097] 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. An amorphous quartz sand, the mass fraction of quartz sand particles with a first density greater than 2.19 g / cm3 and less than 2.24 g / cm3 is not greater than 8%; the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm3 and less than 2.24 g / cm3, the mass fraction of quartz sand particles with the second density is greater than 91%, preferably the mass fraction is greater than 95%, more preferably the mass fraction is greater than 97%. 3 3 ​​ 2. The amorphous quartz sand of claim 1, wherein, The mass percentage of quartz sand particles with a density less than the third density is no more than 1%.

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

4. The amorphous 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 / cm 3 and less than 0.3 g / cm 3 .

5. The amorphous quartz sand of claim 1, wherein, The impurity content of the amorphous quartz sand is less than or equal to 30 ppm.

6. The amorphous quartz sand of claim 1, wherein, The mass percentage of quartz sand particles with a diameter less than 175 μm is less than or equal to 15%, and the mass percentage of quartz sand particles with a diameter between 175 μm and 250 μm is greater than or equal to 75%. Alternatively, the mass percentage of quartz sand particles with a diameter of 250μm to 325μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a diameter of 325μm to 425μm is less than or equal to 63%; Alternatively, the mass percentage of quartz sand particles with a diameter of 250μm to 330μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a diameter of 330μm to 430μm is less than or equal to 63%.

7. The amorphous quartz sand of claim 1, wherein, The mass percentage of quartz sand particles with a density greater than the first density is no more than 5%.

8. A body for a quartz crucible, wherein, Prepared from quartz sand material comprising amorphous quartz sand as described in any one of claims 1 to 7.

9. The body of a quartz crucible according to claim 8, wherein, The amorphous quartz sand accounts for 10% to 30% of the mass of the quartz crucible blank.

10. The body of a quartz crucible according to claim 8, wherein, Along the direction from the inside out, the blank of the quartz crucible includes an inner layer, a middle layer, and an outer layer.

11. The blank of the quartz crucible according to claim 10, wherein, The inner layer of quartz sand contains amorphous quartz sand, and the amorphous quartz sand in the inner layer is defined as first amorphous quartz sand; in the first amorphous quartz sand, the mass percentage of quartz sand particles with a particle size of less than 175μm is less than or equal to 15%, and the mass percentage of quartz sand particles with a particle size of 175μm-250μm is greater than or equal to 75%; And / or, The intermediate layer of quartz sand contains amorphous quartz sand, and the amorphous quartz sand in the intermediate layer is defined as first amorphous quartz sand; in the first amorphous quartz sand, the mass percentage of quartz sand particles with a particle size of less than 175 μm is less than or equal to 15%, and the mass percentage of quartz sand particles with a particle size of 175 μm to 250 μm is greater than or equal to 75%; Alternatively, the amorphous quartz sand in the middle layer is defined as the second amorphous quartz sand, in which the mass percentage of quartz sand particles with a particle size of 250μm~325μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 325μm~425μm is less than or equal to 63%; And / or, The outer layer of quartz sand contains amorphous quartz sand, and the amorphous quartz sand in the outer layer is defined as third amorphous quartz sand; in the third amorphous quartz sand, the mass percentage of quartz sand particles with a particle size of 250μm~330μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 330μm~430μm is less than or equal to 63%.

12. The body of a quartz crucible according to claim 10, wherein, 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.

13. A quartz crucible, prepared using a blank of a quartz crucible as described in any one of claims 8 to 12.

14. A method for preparing a quartz crucible, comprising: The quartz crucible is obtained by melting quartz sand containing amorphous quartz sand. The mass ratio of the quartz sand particles with the first density in the amorphous quartz sand is not more than 8%; the second density of the amorphous quartz sand is greater than or equal to 2.19 g / cm 3 and less than 2.24 g / cm 3 The mass ratio of the quartz sand particles with the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.