Quartz sand, quartz crucible and blank thereof, and preparation method

Abstract

The present invention belongs to the technical fields of quartz sand sorting and quartz crucible melting, and provides a quartz sand, a quartz crucible and a blank thereof, and a preparation method. If the quartz sand has an α-quartz crystal form, the mass proportion of quartz sand particles having a density less than or equal to a first density is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.63 g / cm3 and less than 2.66 g / cm3. If the quartz sand is amorphous synthetic quartz sand, the mass proportion of quartz sand particles having a density less than or equal to the first density is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm3 and less than 2.3 g / cm3. If the quartz sand is amorphous quartz sand, the mass proportion of quartz sand particles having a density greater than a third density 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, and the mass proportion of quartz sand particles having a density equal to the second density is greater than 91%.

Description

Quartz sand, quartz crucible and its body, and preparation method

[0001] Cross-reference to Related Applications

[0002] This application claims priority to Chinese Patent Application No. 2024117181506, filed on November 27, 2024, entitled “Quartz sand, quartz crucible and its body, and preparation method” and Chinese Patent Application No. 2024117185598, filed on November 27, 2024, entitled “Amorphous quartz sand, quartz crucible and its body, and preparation method”, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of quartz sand sorting and quartz crucible melting, in particular, the present application relates to a kind of quartz sand, quartz crucible and its body, and preparation method. BACKGROUND

[0004] As a molten silicon container for photovoltaic or semiconductor Czochralski monocrystalline silicon, the quality of the quartz crucible directly affects the crystal pulling effect of the monocrystalline silicon rod, for example, the yield or quality of the monocrystalline silicon rod. In addition, as a key consumable, the cost of the quartz crucible also directly affects the cost of the subsequent silicon wafer and the cost of the final photovoltaic module or chip.

[0005] The quality and cost of the quartz crucible are largely based on the quality and cost of the main raw material, quartz sand. In the prior art, the quality of quartz sand is controlled by purity, for example, the quartz sand used in the photovoltaic and communication industries reaches 4N; the purity used in the semiconductor or chip field is at the 5N level. With the improvement of beneficiation and purification technology, the cost of the quartz crucible is greatly reduced, which also leads to unstable quality of the quartz crucible and the monocrystalline silicon rod, which is mainly related to the detection of purity. The current purity detection method is mainly chemical analysis and ICP detection, which has small sample size and poor representativeness. Further, due to the low impurity content, it belongs to low impurity detection, which is difficult to detect and has relatively large detection error. Therefore, there is an urgent need for a convenient and fast quartz sand quality control that can meet the actual production to prepare a quartz crucible to meet the cost and quality requirements of Czochralski monocrystalline silicon.

[0006] Further, the quartz crucible used after the single crystal silicon drawing is completed will be discarded to form waste quartz crucible, which is generally stacked or buried, affecting the environment and requiring a certain cost. At present, there are documents disclosing a method and product for producing quartz sand and fused quartz sand from waste quartz crucible. The quartz sand prepared from the waste quartz crucible is mostly amorphous quartz sand, which has low cost, but is currently only used as a filler for metallurgical raw materials, porcelain and refractory materials or construction machinery, with small benefits. The existing quartz crucible is mainly prepared from natural quartz sand, which is expensive, resulting in high preparation cost of the quartz crucible. 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 seen so far. SUMMARY

[0007] Therefore, in order to at least partially solve at least one of the above-mentioned technical problems, the present application provides a quartz sand, a quartz crucible and a body thereof, and a preparation method.

[0008] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0009] According to an embodiment of one aspect of the present application, a quartz sand is provided, having an α-quartz crystal form, a mass proportion of quartz sand particles less than or equal to a first density being not more than 4%, a second density of the quartz sand being greater than or equal to 2.63 g / cm 3 and less than 2.66 g / cm 3 .

[0010] According to an embodiment of another aspect of the present application, a quartz sand is provided, being an amorphous synthetic quartz sand, a mass proportion of quartz sand particles less than or equal to a first density being not more than 4%, a second density of the quartz sand being greater than or equal to 2.2 g / cm 3 and less than 2.3 g / cm 3 .

[0011] According to an embodiment of still another aspect of the present application, a quartz sand is provided, being an amorphous quartz sand, a mass proportion of quartz sand particles greater than a third density being not more than 8%; a second density of the amorphous quartz sand being greater than or equal to 2.19 g / cm 3 and less than 2.24 g / cm 3 , a mass proportion of quartz sand particles equal to the second density being greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0012] According to an embodiment of another aspect of the present application, a body of a quartz crucible is provided, prepared from the quartz sand as described above.

[0013] According to an embodiment of the application, a quartz crucible is provided, which is prepared by using the blank of the quartz crucible as described above.

[0014] According to an embodiment of the application, a preparation method of a quartz crucible is provided, which comprises: melting by using quartz sand to obtain the quartz crucible; wherein the quartz sand has an alpha-quartz crystal form, the mass percentage of quartz sand particles with a first density is not more than 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 .

[0015] According to an embodiment of the application, a preparation method of a quartz crucible is provided, which comprises: melting by using quartz sand to obtain the quartz crucible; wherein the quartz sand is amorphous synthetic quartz sand, the mass percentage of quartz sand particles with a 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 .

[0016] According to an embodiment of the application, a preparation method of a quartz crucible is provided, which comprises: melting by using quartz sand to obtain the quartz crucible; wherein the mass percentage of quartz sand particles with a third density of 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 percentage of quartz sand particles with a second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0017] According to the embodiments of the application, the density distribution of the crystalline quartz sand and the amorphous synthetic quartz sand is controlled within the above range, the quartz sand particles containing impurities and inclusions are removed, and the quartz sand can be controlled to a high quality. Therefore, the quality of the quartz crucible melted by using the quartz sand is improved, and the crucible melting qualification rate and the single crystal silicon pulling effect are high.

[0018] In addition, according to the embodiments of the application, the density distribution of the amorphous quartz sand is controlled within the above range, the amorphous quartz sand particles containing impurities, inclusions and / or crystallization phases are removed, and therefore the quartz crucible for crystal pulling can be prepared by using the amorphous quartz sand, and the preparation cost of the quartz crucible is effectively reduced. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the application clearer, the application will be further described in detail below with specific embodiments.

[0020] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the application. However, it will be apparent to one skilled in the art that one or more embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present application.

[0021] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the term "includes" has the same open-ended meaning as "comprising" and "including" and indicates the presence of the stated features but not to the exclusion of one or more additional features.

[0022] In situations where similar terminology is used, but for which different meanings can apply, it is to be noted that such terminology is used only in reference to specific embodiments as appropriate and applicable. It is also to be noted that like terminology used in different situations has different meanings. For example, as used herein, the expression "at least one of A, B and C" can mean A only, B only, C only, or any combination of A, B and / or C. As used herein, the expression "at least one of A, B or C" can mean A only, B only, C only, or any combination of A, B and / or C.

[0023] In the related art of manufacturing quartz crucibles, the production raw material is mainly natural quartz sand in a crystalline state, the quality of which directly affects the quality of the subsequent manufacturing of quartz crucibles, and the effect of using the quartz crucibles for single crystal silicon pulling. Of course, less commonly, there are also some non-crystalline synthetic quartz sand prepared by chemical synthesis technology (for example, gas phase synthesis technology, liquid phase synthesis technology, fluorosilicic acid technology, etc.) as production raw materials to manufacture quartz crucibles. The evaluation of the quality performance of the crystalline quartz sand mainly focuses on appearance and impurity content indicators, while the non-crystalline synthetic quartz sand mainly refers to the evaluation indicators of the quality performance of the crystalline quartz sand.

[0024] However, through a large number of experiments by the applicant, it is found that even if the quartz sand that meets the appearance and impurity content indicators is used, the quartz crucible melted from it still has low quality.

[0025] In the continuous research and discovery of the applicant, the applicant found that the main defective sand in quartz sand is inclusion (mainly refers to those inclusions which will cause bubble, impurity precipitation or stress concentration in subsequent smelting process, such as gas-liquid phase rich inclusions or solid inclusions containing metal impurity minerals), and the inclusion and other defects are mainly introduced during the melting of the crucible. The density of these defective sand is smaller. In the related art, there is a lack of effective means for detecting such large batch of quartz sand samples, which has become a big problem for further improving the quality of quartz sand, and has also affected the improvement of the quality of quartz crucible.

[0026] In the process of implementing the concept of the present application, it is found that by controlling the density distribution of the quartz sand, the influence of impurities, inclusions and other adverse factors can be effectively reduced, so that the quartz sand can be more accurately controlled at a higher quality. Therefore, the quartz crucible melted by the quartz sand exhibits relatively consistent high quality.

[0027] Specifically, according to an embodiment of one aspect of the present application, a quartz sand having an alpha-quartz crystal form, a mass fraction of quartz sand particles less than or equal to a first density is not greater than 4%, and a 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 .

[0028] In the present application, the "quartz sand" refers to a plurality of quartz sand particles having a crystal structure, i.e. crystalline quartz sand such as quartz sand having an alpha-quartz crystal form, or amorphous synthetic quartz sand and amorphous quartz sand having an amorphous structure. It can be understood that the "quartz sand" protected in the present application refers to a batch of quartz sand used for the preparation of quartz crucible, each batch of quartz sand may be several tens of kilograms, several hundred kilograms or several tons, and each batch contains a large number of quartz sand particles.

[0029] It should be noted that in the present application, for the quartz sand having an alpha-quartz crystal form and the amorphous synthetic quartz sand, there are a first density and a second density; for the amorphous quartz sand, there are a first density, a second density and a third density.

[0030] The "second density" of the present application refers to the density of the sorting liquid when the quartz sand is in a suspended state in the sorting liquid except for a small amount of quartz sand that is always floating on the sorting liquid. The "first density" of the present application refers to the density of the sorting liquid when the quartz sand and the sorting liquid appear the second density, and then the density of the sorting liquid is reduced by adding ethanol. After the addition is completed, the quartz sand floating on the sorting liquid is layered in the sorting liquid for the first time, and the density of the sorting liquid is the first density.

[0031] The "third density" of the present application refers to the density of the sorting liquid when the quartz sand is in a suspended state in the sorting liquid except for a small amount of quartz sand that is always floating on the sorting liquid. The "second density" of the present application refers to the density of the sorting liquid when the quartz sand is in a suspended state in the sorting liquid except for a small amount of quartz sand that is always floating on the sorting liquid. The "first density" of the present application refers to the density of the sorting liquid when the quartz sand and the sorting liquid appear the second density, and then the density of the sorting liquid is reduced by adding ethanol. After the addition is completed, the quartz sand floating on the sorting liquid is layered in the sorting liquid for the first time, and the density of the sorting liquid is the first density.

[0032] It can be understood that for the quartz sand with α-quartz crystal form and the non-crystalline synthetic quartz sand, the second density appears first, and then the first density appears by reducing the density of the sorting liquid. The value of the second density is greater than the value of the first density. For the non-crystalline quartz sand, the third density appears first, and then the second density appears by reducing the density of the sorting liquid, and then the first density appears. The value of the third density is greater than the value of the second density, and the value of the second density is greater than the value of the first density.

[0033] It can be understood that the "density", "second density" and "first density" of the present application, and the "third density" below all represent the physical properties of the quartz sand itself, which is affected by impurities such as metal elements and inclusions and the like existing in the quartz sand itself, but is different from the bulk (stacking) density, and generally does not change with the particle size distribution index. The mass percentage less than or equal to the first density refers to the ratio of the total weight of all quartz sand particles that meet the condition that the density of a single particle of quartz sand is less than or equal to the first density to the weight of the entire batch of quartz sand in the entire batch of quartz sand.

[0034] For the convenience of understanding, for the quartz sand with α-quartz crystal form, the first density is marked as A, the mass percentage of the quartz sand particles with a density less than or equal to A is ≤4%, the second density is marked as B, and then 2.66g / cm 3 >B≥2.63g / cm 3 At this time, since the second density range requirement and the mass percentage requirement of the quartz sand particles in the first density range (i.e. less than or equal to the first density) need to be met, the quartz sand particles with too high or too low density due to impurities or inclusions and the like in the quartz sand are removed, so that the quartz sand as a whole exhibits fewer inclusions defects and fewer impurities, and is more likely to meet the smelting requirements of the quartz crucible.

[0035] Exemplarily, for the quartz sand with α-quartz crystal form, the mass percentage of the quartz sand particles less than or equal to the first density A may 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% and the like. The second density B may be, for example, 2.630g / cm 3 , 2.632g / cm 3 , 2.634g / cm 3 , 2.635g / cm 3 , 2.638g / cm 3 , 2.640g / cm 3 , 2.642g / cm 3 , 2.645g / cm 3 , 2.648g / cm 3 , 2.650g / cm 3 , 2.653g / cm 3 , 2.654g / cm 3 , 2.656g / cm 3 , 2.658g / cm 3 , 2.659g / cm 3 and the like.

[0036] In a specific embodiment, the second density, the first density and the mass fraction of quartz sand particles less than or equal to the first density of the quartz sand having the alpha-quartz crystal form and the amorphous synthetic quartz sand can be measured and evaluated by the following operations.

[0037] The weight of a portion of a batch of quartz sand, for example, 5 kg, is measured as the quartz sand to be evaluated. The quartz sand to be evaluated is added to 7.5 L of a sorting liquid (the sorting liquid is tribromomethane to which 3 wt% of an ethanol stabilizer is added, and the density of the heavy liquid tribromomethane at a constant temperature of 20°C is 2.8804 g / ml) at a constant temperature of 20°C and stirred for 5 minutes at a stirring speed of 20 r / min. After stirring, the mixture is left to stand for 5 minutes.

[0038] After standing, if all the quartz sand is at the bottom of the sorting liquid or in a suspended state (that is, neither moving upward nor downward), it is determined that the entire batch of quartz sand is unqualified, and the next step is not performed.

[0039] After standing, if all the quartz sand is in a floating state, ethanol is added to adjust the density of the sorting liquid. Each adjustment is to add 0.002 g / cm 3 of ethanol to reduce the density. Each adjustment requires stirring for 5 minutes at a stirring speed of 20 r / min, and after stirring, the mixture is left to stand for 5 minutes. The movement trajectory of the quartz sand is observed while adjusting the density.

[0040] If the quartz sand appears to be uniformly suspended, that is, except for a small amount of quartz sand that is always floating on the sorting liquid, neither moving upward nor downward, the density of the sorting liquid at this time is the second density of the quartz sand.

[0041] If the quartz sand begins to stratify, that is, the sorting liquid that does not contain quartz sand is in the middle of two layers of sorting liquid containing quartz sand, a small amount of quartz sand is in a floating state, and most of the quartz sand is below the sorting liquid, the density of the sorting liquid at this time is the first density.

[0042] 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 the weight of the quartz sand particles in the upper layer is measured. The mass fraction of the weight of the quartz sand particles in the upper layer to the weight of all the quartz sand to be evaluated is calculated. This mass fraction is the mass fraction of the quartz sand particles less than or equal to the first density.

[0043] In an alternative embodiment, the quartz sand having the alpha-quartz crystal form can be the first quartz sand, the mass percentage of the quartz sand with a particle size of 75-150 μm 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 the quartz sand with a particle size greater than 150 μm 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 the quartz sand with a particle size less than 75 μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0044] Alternatively, the quartz sand having the alpha-quartz crystal form can be the second quartz sand, the mass percentage of the quartz sand with a particle size of 150-212 μm 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 the quartz sand with a particle size greater than 212 μm 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 the quartz sand with a particle size less than 110 μm is less than or equal to 12%, for example, it can be 12%, 11%, 10%, 8%, 6%, 5%, 3%, 1%, 0.1%, etc.

[0045] Alternatively, the quartz sand having the alpha-quartz crystal form can be the third quartz sand, the mass percentage of the quartz sand with a particle size of 150-212 μm 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 the quartz sand with a particle size greater than 212 μm 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 the quartz sand with a particle size less than 110 μm is less than or equal to 15%, for example, it can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0046] The first quartz sand, the second quartz sand and the third quartz sand have different particle size distributions, so they can be applied to different implementation scenarios, for example, as quartz sand materials for different layers of a smelting quartz crucible, different particle size distributions of the quartz sand can be used as quartz sand materials for different layers of the quartz crucible from the inside to the outside according to the bubble distribution characteristics and requirements of the quartz crucible from the inside to the outside, so that a high-quality quartz crucible can be prepared.

[0047] Exemplarily, along a direction from inside to outside, the quartz crucible can include an inner layer, a middle layer and an outer layer, and the quartz sand used for each layer has a higher performance requirement from outside to inside. The first quartz sand can be used as the inner layer quartz sand, the second quartz sand can be used as the middle layer quartz sand, and the third quartz sand can be used as the outer layer quartz sand. Thus, in the process of melting the quartz crucible, a trend of gradually increasing the average particle size of the quartz sand in the direction from the inside of the quartz crucible to the outside is formed, which is beneficial to remove the bubbles in a vacuum way from the inside to the outside, and further makes the bubble content of the prepared quartz crucible gradually decrease in the direction from the outside to the inside, thereby improving the quality of the quartz crucible.

[0048] According to the embodiments of the present application, further optionally, in the quartz sand with α-quartz crystal form, the mass percentage of the quartz sand particles less than or equal to the first density is not more than 1%, for example, it can be 1%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0%.

[0049] In this way, the influence of impurities and other defects in the quartz sand with α-quartz crystal form is further reduced, and the quality of the quartz crucible melted by the quartz sand can be further improved, and the quartz sand is more suitable for use as the inner layer quartz sand and / or the middle layer quartz sand.

[0050] Exemplarily, for the quartz sand with α-quartz crystal form, the mass percentage of the quartz sand particles less than or equal to the first density is more than 1% and not more than 2.5%, for example, it can be 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., and is mainly suitable for use as the middle layer quartz sand, but is not limited thereto, and the melting effect of the quartz crucible is better when the quartz sand is used as the outer layer quartz sand.

[0051] Exemplarily, for the quartz sand with α-quartz crystal form, the mass percentage of the quartz sand particles less than or equal to the first density is not more than 0.5%, for example, it can be 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, etc., and is mainly suitable for use as the inner layer quartz sand, but is not limited thereto, and the melting effect of the quartz crucible is better when the quartz sand is used as the middle layer quartz sand.

[0052] Further optionally, in the quartz sand with α-quartz crystal form, the difference between the second density and the first density is greater than or equal to 0.001 g / cm 3 The difference is mainly controlled by the accuracy of the sorting liquid. If the difference is too small, the first density and the second density are difficult to distinguish.

[0053] Further alternatively, in the quartz sand having the α-quartz crystal form, 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 , for example, can be 2.630 g / cm 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 , 2.639 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 , etc. In this way, the performance requirements of the outer layer of the quartz sand material of the quartz crucible can be met, and the sorting cost is low. Alternatively, 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 , in this way, the performance requirements of the middle layer of the quartz sand material or the outer layer of the quartz sand material of the quartz crucible can be met. Alternatively, the second density is greater than or equal to 2.65 g / cm 3 and less than 2.66 g / cm 3 , in this way, the performance requirements of the inner layer of the quartz sand material, the middle layer of the quartz sand material or the outer layer of the quartz sand material of the quartz crucible can be met.

[0054] According to the embodiments of the present application, the impurity or inclusion content can be effectively controlled within a certain range through the density distribution, however, there can still be a small amount of impurities that do not have a significant effect on the density distribution. Therefore, the present application can further control the impurity content to meet the higher impurity content requirements of the production raw materials during the melting process of the quartz crucible. The impurity content of the quartz sand having the α-quartz crystal form provided by the present application is less than or equal to 25 ppm. In this way, when the impurity content of the quartz sand is not higher than 25 ppm, it is suitable as the outer layer of the quartz sand material of the quartz crucible, and when the impurity content meets less than or equal to 20 ppm, it can be used as the inner, middle and outer layers of the quartz sand material of the quartz crucible, and its performance will be better.

[0055] According to the embodiments of the present application, the quartz sand with the alpha-quartz crystal form is derived from natural quartz sand. The natural quartz sand has excellent structural strength and thermal stability, so that it can be used as the raw material of the quartz crucible. In addition, the natural quartz sand has abundant reserves and relatively low mining and utilization cost, which helps to reduce the cost and ensure the production not to be affected by the shortage of raw materials. Further, the natural quartz sand with the alpha-quartz crystal form has higher purity of silicon dioxide and more stable crystal form, which ensures that the crucible prepared therefrom can maintain chemical stability at high temperature and reduces the influence of impurities on the quality of the crucible.

[0056] According to the embodiments of another aspect of the present application, a green body of a quartz crucible is also provided, which is prepared from the quartz sand with the alpha-quartz crystal form as described above. Since the density distribution and the sorting method of the quartz sand are the same as described above, they will not be repeated here.

[0057] According to the embodiments of the present application, the preparation method of the green body of the quartz crucible can specifically include: sequentially arranging the outer layer quartz sand material, the middle layer quartz sand material and the inner layer quartz sand material in the inside of the crucible mold in the direction from outside to inside to obtain the green body of the quartz crucible. The outer layer quartz sand material, the middle layer quartz sand material and the inner layer quartz sand material are respectively prepared from the quartz sand with the alpha-quartz crystal form as described above, and the second density of the quartz sand of the outer layer quartz sand material is less than or equal to the second density of the quartz sand of the inner layer quartz sand material, so as to meet the performance requirements of the middle layer and the inner layer quartz sand material while having the advantage of lower cost.

[0058] According to the embodiments of the present application, further optionally, the second density of the quartz sand of the middle layer quartz sand material is less than or equal to the second density of the quartz sand of the inner layer quartz sand material. For the same type of quartz sand, for example, both are crystalline quartz sand, the higher the density is, the smaller the inclusion content is, thereby being beneficial to smelt the transparent layer with less defects and higher strength. By using quartz sands with different densities as different layered quartz sand materials of the quartz crucible, it is beneficial to control the bubble content of the quartz crucible to decrease from outside to inside, thereby improving the quality of the quartz crucible.

[0059] Exemplarily, the second density of the quartz sand of the inner layer quartz sand material 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 quartz sand material 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 .

[0060] According to the embodiment of the present application, the average particle size of the inner layer quartz sand, the middle layer quartz sand and the outer layer quartz sand in the body of the quartz crucible increases in turn. In this way, the crucible melting can be facilitated, and the distribution requirement that the bubble content of the different layers of the quartz crucible gradually increases from the inside to the outside can be met.

[0061] According to the embodiment of the present application, further optionally, the crucible mold can be a rotation molding mold with any inclination angle, for example, a graphite mold can be inserted into a metal water cooling jacket, and the outer layer quartz sand, the middle layer quartz sand and the inner layer quartz sand are manually formed in turn by using the centrifugal force and a forming rod to form a crucible shape, so as to obtain the body of the quartz crucible.

[0062] According to the embodiment of the present application, the quartz sand used in the body of the quartz crucible can 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 the above, which will not be repeated here, so as to meet the requirement of the particle size distribution of the inner layer quartz sand, the middle layer quartz sand and the outer layer quartz sand.

[0063] For the convenience of description, for example, the first quartz sand can be used for the inner layer quartz sand. And / or, the second quartz sand can be used for the middle layer quartz sand. And / or, the third quartz sand can be used for the outer layer quartz sand. The quartz sand with the α-quartz crystal form of the present application can be more flexibly applied to the quartz sand of different layers of the quartz crucible, and the quartz crucible obtained has a higher melting qualification rate and exhibits a higher single crystal silicon pulling effect.

[0064] According to the embodiment of the present application, further optionally, the mass percentage of the inner layer quartz sand is 10% to 30%, for example, can be 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% and the like, the mass percentage of the middle layer quartz sand is 20% to 45%, for example, can be 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% and the like, and the mass percentage of the outer layer quartz sand is 35% to 50%, for example, can be 35%, 38%, 40%, 42%, 45%, 48%, 50% and the like, with the total mass of the body of the quartz crucible being 100%. In this way, the performance requirement of each layer of the quartz crucible can be met.

[0065] Further, according to the embodiment of the present application, the present application further provides a preparation method of a quartz crucible, which comprises melting by using the quartz sand described above to obtain the quartz crucible. The quartz sand has the α-quartz crystal form, the mass percentage of the quartz sand particles with the first density less than or equal to 2.63 g / cm 3 and less than 2.66 g / cm3 The density distribution of the quartz sand and the sorting method are the same as the foregoing, and thus are not described herein.

[0066] More specifically, the melting using the quartz sand material containing the quartz sand having the alpha-quartz crystal form as described above to obtain the quartz crucible can specifically include operations S301 to S302:

[0067] In operation S301, the outer layer quartz sand material, the middle layer quartz sand material and the inner layer quartz sand material are sequentially arranged in the inside of the crucible mold along the direction from outside to inside to obtain a blank of the quartz crucible, and the average particle size of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material increases in turn.

[0068] In operation S302, the blank of the quartz crucible is subjected to arc melting to obtain the quartz crucible, so that the quartz crucible includes the inner layer, the middle layer and the outer layer along the direction from inside to outside, and the bubble content of the inner layer, the middle layer and the outer layer increases in turn; 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 quartz sand having the alpha-quartz crystal form as described above.

[0069] According to the embodiments of the present application, the quality of the quartz sand material has high consistency after being controlled by the density distribution, so that the bubble content of the quartz crucible from inside to outside can be more effectively controlled by the particle size distribution of the quartz sand.

[0070] According to the embodiments of the present application, in operation S301, the arrangement of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material is the same as the foregoing, and the selection of the crucible mold and the selection of the blank forming method can be the same as the foregoing, which are not described herein.

[0071] According to the embodiments of the present application, in operation S302, the operation of arc melting can include inserting the electrode into the formed blank after the electrode is started to arc, so that the electrode is quickly melted into molten quartz in the shape of the crucible. The operation of arc melting is performed under negative pressure, and the gas is extracted from the inside to the outside, so that the bubble content gradually increases from the inside to the outside, thereby improving the quality of the quartz crucible.

[0072] According to the embodiments of the present application, a quartz crucible prepared by using the blank of the quartz crucible as described above, or prepared by using the preparation method as described above is provided. The quartz crucible provided by the present application has high melting quality, and exhibits good crystal pulling effect and service life.

[0073] According to the embodiments of the present application, a quartz sand is also provided. The quartz sand is amorphous synthetic quartz sand, and the mass fraction of the quartz sand particles less than or equal to the first density is not greater than 4%, and the second density of the quartz sand is greater than or equal to 2.2 g / cm 3 and less than 2.3 g / cm3 .

[0074] wherein, herein, the "amorphous synthetic quartz sand" refers to the quartz sand obtained by artificial synthesis, and the quartz sand particles do not have obvious crystal structure, thereby being distinguished from the crystalline quartz sand (for example, natural quartz sand). It can be understood that the "quartz sand" protected in the present application refers to a batch of quartz sand used for the preparation of quartz crucibles, and each batch of quartz sand can be dozens of kilograms, hundreds of kilograms or several tons, and each batch contains a large number of quartz sand particles.

[0075] wherein, herein, the meanings of the "second density" and the "first density" are the same as the aforementioned, and the meaning of the mass percentage of the quartz sand particles with a density less than or equal to the first density is the same as the aforementioned, and will not be repeated here.

[0076] For the convenience of understanding, for the amorphous synthetic quartz sand, the first density is marked as A, the mass percentage of the quartz sand particles with a density less than or equal to A is ≤4%, the second density is marked as B, and B is greater than or equal to 2.2 g / cm 3 , less than 2.3 g / cm 3 . At this time, since the second density range requirement and the mass percentage requirement of the quartz sand particles with a density less than or equal to the first density need to be met, the quartz sand particles with too low density such as impurities or inclusions in the quartz sand can be removed, so that the quartz sand as a whole exhibits fewer gas-liquid inclusion defects and fewer impurities, and is more likely to meet the smelting requirements of the quartz crucible.

[0077] Exemplarily, for the amorphous synthetic quartz sand, the mass percentage of the quartz sand particles with a density less than or equal to the first density A can be 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%, and the like. The second density B can be 2.20 g / cm 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 , and the like.

[0078] In a specific embodiment, the second density, the first density and the mass percentage of the quartz sand particles with the first density of the amorphous synthetic quartz sand can be measured by gravity separation, and can be measured and evaluated by the above-mentioned operation of the crystalline quartz sand.

[0079] In an alternative embodiment, the amorphous synthetic quartz sand can be a fourth quartz sand, the mass percentage of the quartz sand with a particle size of 75-150 μm is greater than or equal to 75%, for example, can be 75%, 77%, 80%, 85%, 88%, 90%, 95%, 99%, 99.9%, etc., the mass percentage of the quartz sand with a particle size greater than 150 μm is less than or equal to 5%, for example, can be 5%, 4%, 3%, 2%, 1%, 0.1%, etc., and the mass percentage of the quartz sand with a particle size less than 75 μm is less than or equal to 15%, for example, can be 15%, 13%, 10%, 8%, 5%, 3%, 1%, 0.1%, etc.

[0080] The fourth quartz sand can be used as an inner layer of quartz sand material, and can be used in combination with the second quartz sand and the third quartz sand, the second quartz sand can be used as a middle layer of quartz sand material, and the third quartz sand can be used as an outer layer of quartz sand material. Thus, during the melting of the quartz crucible, the average particle size of the quartz sand gradually increases in the direction from the inside to the outside of the quartz crucible, which is beneficial to the removal of bubbles from the inside to the outside in a vacuum manner, and further makes the bubble content of the prepared quartz crucible gradually decrease in the direction from the outside to the inside, thereby improving the quality of the quartz crucible.

[0081] According to the embodiments of the present application, further alternatively, in the above-mentioned amorphous synthetic quartz sand, the difference between the first density and the second density is greater than or equal to 0.001 g / cm 3 The difference is mainly controlled by the accuracy of the sorting liquid. If the difference is too small, the first density and the second density are difficult to distinguish.

[0082] According to the embodiments of the present application, the density distribution can effectively control the impurity or inclusion content within a certain range, however, there can still be a small amount of impurities that do not have a significant effect on the density distribution. Therefore, the present application can further control the impurity content to meet the higher impurity content requirement of the production raw material in the melting process of the quartz crucible. The impurity content of the amorphous synthetic quartz sand provided by the present application is less than or equal to 20 ppm, which can be used as an inner layer of quartz sand material of the quartz crucible.

[0083] According to the embodiments of another aspect of the present application, a quartz crucible blank is also provided, which is prepared by the above-mentioned amorphous synthetic quartz sand. Since the density distribution of the quartz sand and the sorting method are the same as the above, they will not be described here.

[0084] According to the embodiment of the present application, the preparation method of the blank body of the quartz crucible can specifically include: sequentially arranging the outer layer quartz sand material, the middle layer quartz sand material and the inner layer quartz sand material in the inside of the crucible mold along the direction from outside to inside to obtain the blank body of the quartz crucible. The inner layer quartz sand material is prepared by the amorphous synthetic quartz sand. In this way, the performance requirements of the inner layer quartz sand material can be met.

[0085] According to the embodiment of the present application, the average particle size of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material in the blank body of the quartz crucible increases in turn. In this way, the distribution requirement that the bubble content of the quartz crucible gradually increases from inside to outside in different layers can be met.

[0086] According to the embodiment of the present application, the quartz sand used in the blank body of the quartz crucible can contain the fourth quartz sand, which can be used in combination with at least one of the second quartz sand and the third quartz sand, so that the requirements of the particle size distribution of the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material can be met.

[0087] For the convenience of illustration, the inner layer quartz sand material can use the fourth quartz sand. The middle layer quartz sand material can use the second quartz sand; and / or, the outer layer quartz sand material can use the third quartz sand. The quartz sand material of the present application can be more flexibly applied to the quartz sand material in different layers of the quartz crucible, and the prepared quartz crucible has a higher melting qualification rate and shows a higher single crystal silicon pulling effect.

[0088] According to the embodiment of the present application, further optionally, the total mass of the blank body of the quartz crucible is 100%, the mass ratio of the inner layer quartz sand material is 10% to 30%, for example, it can be 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% and the like, the mass ratio of the middle layer quartz sand material is 20% to 45%, for example, it can be 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% and the like, and the mass ratio of the outer layer quartz sand material is 35% to 50%, for example, it can be 35%, 38%, 40%, 42%, 45%, 48%, 50% and the like. In this way, the performance requirements of each layer of the quartz crucible can be met.

[0089] Further, according to the embodiment of the present application, the present application also provides a preparation method of a quartz crucible, which includes melting and casting by using the amorphous synthetic quartz sand to obtain the quartz crucible. The mass ratio of the quartz sand particles with a density 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 3The density distribution and sorting measurement method of the amorphous synthetic quartz sand and the melting method of the quartz crucible are the same as the foregoing, and thus will not be described again.

[0090] According to another aspect of the embodiments of the present application, a quartz crucible prepared by using the quartz crucible and the preparation method is also provided. The quartz crucible provided by the present application has high melting quality, and exhibits good crystal pulling effect and service life.

[0091] As described above, in the prior art related to the preparation of the quartz crucible, the production raw material is generally the crystalline natural quartz sand. The selection index of the crystalline natural quartz sand is mainly to select the natural quartz sand with low impurity content and suitable particle size distribution. Through a large number of experiments of the applicant, it is found that if the selection index of the natural sand is used to select the amorphous quartz sand, the melting qualified rate of the quartz crucible melted therefrom is low. Therefore, the selection standard of the amorphous quartz sand cannot be extended to the standard of the natural sand.

[0092] The inventors of the present application find that the amorphous quartz sand prepared from the waste quartz crucible contains amorphous quartz sand wrapped with bubbles, impurities and / or crystallization phase. The main reason is that the existence of these sands leads to the poor preparation of the quartz crucible.

[0093] The applicant further finds that by controlling the second density of the amorphous quartz sand and the mass proportion of the quartz sand particles greater than the third density, the amorphous quartz sand can be accurately controlled to be of high quality and good consistency. The quartz crucible melted by using the amorphous quartz sand satisfying the density distribution exhibits high and consistent quality.

[0094] Specifically, according to another aspect of the present application, an amorphous quartz sand is provided, the mass proportion of the quartz sand particles greater than the third 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 , and the mass proportion of the quartz sand particles equal to the second density is greater than 91%, preferably greater than 95%, and more preferably greater than 97%.

[0095] In the present application, the "amorphous quartz sand" refers to the quartz sand particles in amorphous state, which is distinguished from the crystalline quartz sand (such as natural quartz sand), and is prepared by crushing and processing the waste quartz crucible. The waste quartz crucible is mainly the quartz crucible used after the Czochralski single crystal silicon. It can be understood that the "amorphous quartz sand" protected by the present application refers to a batch of amorphous quartz sand prepared from the waste quartz crucible. Each batch of amorphous quartz sand may contain a large number of amorphous quartz sand particles (or simply referred to as quartz sand particles), such as tens of kilograms, hundreds of kilograms or several tons.

[0096] wherein the meanings of the "second density", the "first density" and the "third density" are the same as described above, and are not repeated here.

[0097] For the sake of understanding, for the amorphous quartz sand, the third density is marked as C, and the second density is marked as B, 2.19g / cm 3 ≤B<2.24g / cm 3 , and the mass proportion of the quartz sand particles greater than C is not more than 8%. Since the second density and the proportion of the quartz sand particles thereof need to be met, and the proportion of the quartz sand particles greater than the third density needs to be met, the quartz sand particles with higher density such as impurities or crystalline phases wrapped in the amorphous quartz sand are removed, so that the amorphous quartz sand as a whole exhibits fewer defects such as impurities or crystalline phases, and is more likely to meet the smelting requirements of the quartz crucible.

[0098] Exemplarily, the second density B may be, for example, 2.190g / cm 3 , 2.195g / cm 3 , 2.200g / cm 3 , 2.205g / cm 3 , 2.210g / cm 3 , 2.215g / cm 3 , 2.220g / cm 3 , 2.221g / cm 3 , 2.222g / cm 3 , 2.224g / cm 3 , 2.225g / cm 3 , 2.228g / cm 3 , 2.230g / cm 3 , 2.235g / cm 3 , 2.238g / cm 3 , 2.239g / cm 3 , etc. The mass proportion of the quartz sand particles equal to the second density B is greater than 91%, which may be, for example, 91.5%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, etc. The mass proportion of the quartz sand particles greater than the third density may be, for example, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, etc. For the amorphous quartz sand, the mass proportion greater than the third density C refers to the ratio of the total weight of all amorphous quartz sand particles meeting the condition that the density of a single particle of amorphous quartz sand is greater than the third density C to the weight of the entire batch of amorphous quartz sand.

[0099] According to the embodiments of the present application, further optionally, in the amorphous quartz sand as described above, the difference between the second density B and the third density C is greater than or equal to 0.001 g / cm 3 and less than 0.3 g / cm 3 . That is, C and B satisfy the relationship: Δρ1=C-B, and 0.001 g / cm 3 ≤ Δρ1< 0.3 g / cm 3 . Exemplarily, the difference Δρ1may be, for example, 0.001 g / cm 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 , 0.05 g / 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 , etc.

[0100] The size of the difference is determined by the amorphous quartz sand to be sorted on one hand. If the difference is too large, it means that although the quartz sand with consistent quality can be sorted out, there is still a large room for quality improvement. On the other hand, in the process of sorting and measuring, the density range of the sorting solution is affected by the addition of ethanol each time. If the difference is smaller, the density control accuracy of the sorting solution is higher, and the difficulty of layering is greater. By controlling the difference within the above range, the influence of the impurities and crystallization phase defects wrapped in the quartz sand can be further reduced, and the quality of the quartz crucible melted by the quartz sand can be further improved.

[0101] According to the embodiments of the present application, further optionally, the mass percentage of the quartz sand particles with a first density in the amorphous quartz sand of the present application is not greater than 1%.

[0102] Wherein, the meaning of “first density” is the same as described above, and will not be repeated here.

[0103] The mass ratio of the quartz sand particles less than the first density refers to the ratio of the total weight of all the amorphous quartz sand particles meeting the condition that the density of a single particle is less than the first density to the weight of the entire batch of amorphous quartz sand in the entire batch of amorphous quartz sand.

[0104] For the amorphous quartz sand, the first density is marked as A, and the mass ratio of the quartz sand particles with a density less than A is not greater than 1%. Since the amorphous quartz sand of the present application also meets the requirement of the mass ratio of the quartz sand particles less than the first density, the quartz sand particles with a lower density such as wrapped bubbles are removed, so that the amorphous quartz sand as a whole exhibits fewer defects such as bubbles and is more likely to meet the melting requirements of the quartz crucible. For example, the mass ratio of the quartz sand particles less than the first density A can be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0105] In a specific embodiment, the third density, the second density, the first density of the amorphous quartz sand, and the mass ratio of the quartz sand particles greater than the third density, the mass ratio of the quartz sand particles equal to the second density, and the mass ratio of the quartz sand particles less than the first density can be measured by heavy liquid separation, and can be measured and evaluated by the following operations.

[0106] For example, 5 kg of a batch of quartz sand can be weighed as the quartz sand to be evaluated, and the quartz sand to be evaluated can be added to 7.5 L of a separation liquid (the separation liquid is tribromomethane added with 3 wt% of an ethanol stabilizer, and the density of the heavy liquid tribromomethane is 2.8804 g / ml at a constant temperature of 20°C) for stirring at a constant temperature of 20°C. The stirring time is 5 minutes, and the stirring speed is 20 r / min. After stirring, the quartz sand is allowed to stand for 5 minutes.

[0107] After standing, if all the quartz sand is at the bottom of the separation liquid or in a suspended state (that is, neither moving upward nor downward), it indicates that the entire batch of quartz sand is unqualified, and the next step does not need to be performed.

[0108] After standing, if all the quartz sand is in a floating state, ethanol is added to adjust the density of the separation liquid. Each time, 0.002 g / cm3 of ethanol is added to reduce the density. Each time, the quartz sand is stirred for 5 minutes at a stirring speed of 20 r / min, and then allowed to stand for 5 minutes. The motion trajectory of the quartz sand is observed while adjusting:

[0109] When the quartz sand begins to stratify, even if the sorting liquid not containing the quartz sand is in the middle of two layers of sorting liquid containing the quartz sand, most of the quartz sand is in the floating state, and a very small part of the quartz sand is below the sorting liquid, at this time, the density of the sorting liquid is the third density.

[0110] The small part of the quartz sand in the lower layer below the sorting liquid after stratification is separated, and the weight of the quartz sand particles in the lower layer is weighed; at this time, the mass ratio of the weight of the quartz sand particles in the lower layer to the weight of the whole batch of amorphous quartz sand is calculated, and the mass ratio is the mass ratio of the quartz sand particles with the third density.

[0111] After separation, the density of the sorting liquid is adjusted again by adding ethanol; each adjustment is to add 0.002g / cm 3 of ethanol to reduce the density; each adjustment needs to be stirred for 5 minutes, and the stirring speed is 20r / min, and after the stirring is completed, it is static for 5min. Adjust while observing the motion trajectory of the quartz sand:

[0112] When the quartz sand appears uniform suspension distribution, that is, except for a very small number of floating sand floating on the sorting liquid, neither upward movement nor downward movement, at this time, the density of the sorting liquid is the second density of the quartz sand.

[0113] Continue to add ethanol to adjust the density of the sorting liquid; each adjustment is to add 0.002g / cm 3 of ethanol to reduce the density; each adjustment needs to be stirred for 5 minutes, and the stirring speed is 20r / min, and after the stirring is completed, it is static for 5min. Adjust while observing the motion trajectory of the quartz sand:

[0114] When the quartz sand begins to stratify again, even if the sorting liquid not containing the quartz sand is in the middle of two layers of sorting liquid containing the quartz sand, a very small part of the quartz sand is in the floating state, and most of the quartz sand is below the sorting liquid, at this time, the density of the sorting liquid is the first density.

[0115] After stratification, the quartz sand is again divided into an upper layer and a lower layer, the quartz sand particles in the lower layer are separated, and the weight of the quartz sand particles in the lower layer is weighed; the mass ratio of the weight of the quartz sand particles in the lower layer to the weight of all the quartz sand to be evaluated is calculated; the mass ratio is equal to the mass ratio of the quartz sand particles with the second density. The quartz sand particles in the upper layer are separated, and the weight of the quartz sand particles in the upper layer is weighed; the mass ratio of the weight of the quartz sand particles in the upper layer to the weight of all the quartz sand to be evaluated is calculated; the mass ratio is less than the mass ratio of the quartz sand particles with the first density.

[0116] According to the embodiments of the present application, further optionally, for the amorphous quartz sand, the difference between the first density A and the second density B is greater than or equal to 0.001g / cm 3and further preferably less than 0.1 g / cm 3 i.e. B and A satisfy the relationship: Δρ2 = B - A, and 0.001 g / cm 3 ≤ Δρ2 < 0.1 g / cm 3 Exemplarily, the difference Δρ2may be, for example, 0.001 g / cm 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 Δρ2is greater than or equal to 0.001 g / cm 3 and less than 0.01 g / cm 3 . By controlling the difference within the above range, the influence of defects such as bubbles enclosed in the quartz sand can be further reduced, and the quality of the quartz crucible melted using the quartz sand can be further improved.

[0117] According to the embodiments of the present application, the impurity, inclusion and / or crystallization phase content can be effectively controlled within a certain range through the density distribution, however, there can still be a small amount of impurities that do not have a significant impact on the density distribution. Therefore, the present application can further control the impurity content to meet the higher impurity content requirement of the production raw material in the quartz crucible melting process. The impurity content of the amorphous quartz sand provided by the present application can be less than or equal to 30 ppm. Along the direction from the inside to the outside, the quartz crucible can include an inner layer, a middle layer and an outer layer, and for each layer, the performance requirement of the quartz sand used is higher from the outside to the inside. Thus, in the case that the impurity content of the amorphous quartz sand is not higher than 30 ppm, it is suitable as an outer layer sand raw material of the quartz crucible, and in the case that the impurity content meets less than or equal to 20 ppm, the performance of the middle and outer layer sand material of the quartz crucible is more optimal.

[0118] According to embodiments of the present application, the amorphous quartz sand of the present 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, for example, as quartz sand materials for different layers of a fused quartz crucible.

[0119] In an alternative embodiment, the amorphous quartz sand can be a first amorphous quartz sand, the mass fraction of quartz sand particles with a particle size 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.; the mass fraction 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 75%, 78%, 80%, 85%, 90%, 95%, 99%, etc.

[0120] Alternatively, the amorphous quartz sand can be a second amorphous quartz sand, the mass fraction of quartz sand particles with a particle size of 250 μm-325 μm is greater than or equal to 37%, for example, it can be 37%, 40%, 43%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 100%, etc.; the mass fraction of quartz sand particles with a particle size of 325 μm-425 μm is less than or equal to 63%, for example, it can be 63%, 60%, 57%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 0%, etc.

[0121] Alternatively, the amorphous quartz sand can be a third amorphous quartz sand, the mass fraction of quartz sand particles with a particle size of 250 μm-330 μm is greater than or equal to 37%, for example, it can be 37%, 40%, 43%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 100%, etc.; the mass fraction of quartz sand particles with a particle size of 330 μm-430 μm is less than or equal to 63%, for example, it can be 63%, 60%, 57%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 0%, etc.

[0122] According to embodiments of the present application, it can be understood that, under the condition of having the same density distribution, the amorphous quartz sand with different particle size distributions is used as quartz sand materials for different layers of a quartz crucible from the inside to the outside, which reduces the cost while taking into account the quality of the fused quartz crucible.

[0123] According to the embodiments of the present application, the first amorphous quartz sand can be used as the inner layer quartz sand material or the middle layer quartz sand material, the second amorphous quartz sand can be used as the middle layer quartz sand material or the outer layer quartz sand material, and the third amorphous quartz sand can be used as the outer layer quartz sand material. Thus, in the process of melting the quartz crucible, a trend of gradually increasing the average particle size of the amorphous quartz sand in the direction from the inner side to the outer side of the quartz crucible is formed, which is beneficial to remove the bubbles from the inner side to the outer side in a vacuum way, and further makes the bubble content of the prepared quartz crucible gradually decrease in the direction from the outer side to the inner side, thereby improving the preparation qualification rate of the quartz crucible.

[0124] According to the embodiments of the present application, further, in the amorphous quartz sand, the mass percentage of the quartz sand particles greater than the third density is not more than 5%, for example, can be 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5% and the like. In this way, it is beneficial to further reduce the influence of the amorphous quartz sand particles wrapped with impurities or crystalline phase, and the quality of the quartz crucible melted by using the amorphous quartz sand can be further improved, which is especially more suitable for use as the inner layer quartz sand material and / or the middle layer quartz sand material.

[0125] According to the embodiments of the present application, the amorphous quartz sand provided by the present application is derived from the recycled waste quartz crucible, for example, the amorphous quartz sand can be obtained after crushing, screening and high-temperature roasting of the waste quartz crucible. This is because, on the one hand, the production cost and process difficulty of preparing the amorphous quartz sand from the waste quartz crucible sheet are lower than those of the amorphous quartz sand prepared by artificial synthesis; on the other hand, the process of artificially synthesizing the amorphous quartz sand is complicated and easy to introduce more small bubbles. Therefore, compared with the amorphous quartz sand prepared by artificial synthesis, the amorphous quartz sand prepared from the waste quartz crucible sheet still has a great advantage.

[0126] In order to further meet the raw material demand for the preparation of the quartz crucible, the sorted amorphous quartz sand can be further subjected to particle size sorting, so as to obtain amorphous quartz sand with different particle size distributions, for example, the first amorphous quartz sand, the second amorphous quartz sand and the third amorphous quartz sand, and the specific particle size distribution is the same as the foregoing, which will not be described here. The particle size sorting mode can be, for example, including grinding and grading operations. The grinding can be, for example, by at least one device such as a ball mill, a jaw crusher and a roller crusher to refine the quartz sand particles to the required particle size range. The grading can be, for example, to select a screen with different mesh numbers to screen the ground quartz sand into different particle size ranges, or again, to separate the ground quartz sand into different particle size ranges by centrifugal screening.

[0127] Based on the amorphous quartz sand with the above density distribution, a blank of a quartz crucible can be made to melt a quartz crucible with high quality. Specifically, embodiments of another aspect of the present application also provide a blank of a quartz crucible prepared from a quartz sand material containing the amorphous quartz sand as described above. Since the density distribution of the amorphous quartz sand and the heavy liquid separation method are the same as described above, they will not be described here again.

[0128] According to embodiments of the present application, the amorphous quartz sand described above is used as a production raw material to make a blank of a quartz crucible to melt a quartz crucible. Since the overall purity and the number of defects are high, the adverse effects of the amorphous quartz sand containing inclusions, crystalline phases, and bubbles during the melting process are reduced, which is beneficial to melting a quartz crucible, and further enables the amorphous quartz sand prepared from waste quartz crucibles to replace expensive natural quartz sand to prepare a quartz crucible.

[0129] According to embodiments of the present application, in order to further improve the melting quality of the quartz crucible, the mass ratio of the amorphous quartz sand to the blank of the quartz crucible is preferably 10% to 30%, for example, it can be 10%, 13%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, etc. If the mass ratio is too high, the yield of the melted quartz crucible is low; if the mass ratio is too low, it is difficult to balance the process cost and the melting quality.

[0130] Illustratively, taking a quartz crucible including an inner layer, a middle layer, and an outer layer in a direction from inside to outside as an example, the blank of the quartz crucible includes the inner layer, the middle layer, and the outer layer in a direction from inside to outside. The amorphous quartz sand provided by the present application can be a quartz sand material for at least one of the inner layer, the middle layer, and the outer layer, which can replace or at least partially replace the natural quartz sand used in at least one of the inner layer, the middle layer, and the outer layer.

[0131] According to embodiments of the present application, the preparation method of the blank of the quartz crucible can specifically include: in a direction from outside to inside, using quartz sand materials to sequentially set an outer layer, a middle layer, and an inner layer inside a crucible mold to obtain a blank of a quartz crucible. The average particle sizes of the quartz sand materials for the inner layer, the middle layer, and the outer layer increase in turn.

[0132] According to embodiments of the present application, further optionally, the crucible mold can be a rotary forming mold with any inclination angle, for example, a graphite mold can be inserted into a metal water cooling jacket, and the outer layer, the middle layer, and the inner layer of the quartz sand materials are sequentially formed by hand using centrifugal force and a forming rod to form a crucible shape to obtain a blank of a quartz crucible.

[0133] According to the embodiment of the application, the amorphous quartz sand used in the body of the quartz crucible can 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 the aforementioned, and thus the requirement of the particle size distribution of the inner layer quartz sand, the middle layer quartz sand and the outer layer quartz sand can be met.

[0134] For the convenience of description, for example, the inner layer quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the inner layer is defined as the first amorphous quartz sand. And / or, the middle layer quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the middle layer is defined as the first amorphous quartz sand or the second amorphous quartz sand. And / or, the outer layer quartz sand contains the aforementioned amorphous quartz sand, and the amorphous quartz sand in the outer layer is defined as the third amorphous quartz sand. In other words, the first amorphous quartz sand can be used in the inner layer quartz sand or the middle layer quartz sand, the second amorphous quartz sand can be used in the middle layer quartz sand or the outer layer quartz sand, and the third amorphous quartz sand can be used in the outer layer quartz sand. The amorphous quartz sand of the application can be more flexibly applied to the quartz sand of different layers of the quartz crucible, and the prepared quartz crucible has a higher melting qualification rate.

[0135] According to the embodiment of the application, further optionally, the mass ratio of the inner layer quartz sand is 10% to 30%, for example, can be 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% and the like, the mass ratio of the middle layer quartz sand is 20% to 45%, for example, can be 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% and the like, and the mass ratio of the outer layer quartz sand is 35% to 50%, for example, can be 35%, 38%, 40%, 42%, 45%, 48%, 50% and the like, with the total mass of the body of the quartz crucible being 100%. In this way, the performance requirements of each layer of the quartz crucible can be met.

[0136] According to the embodiment of the application, further optionally, the mass ratio of the inner layer quartz sand is 10% to 30%, for example, can be 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30% and the like, the mass ratio of the middle layer quartz sand is 20% to 45%, for example, can be 20%, 23%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45% and the like, and the mass ratio of the outer layer quartz sand is 35% to 50%, for example, can be 35%, 38%, 40%, 42%, 45%, 48%, 50% and the like, with the total mass of the body of the quartz crucible being 100%. In this way, the performance requirements of each layer of the quartz crucible can be met.

[0137] The application further provides a preparation method of a quartz crucible, including melting using quartz sand containing amorphous quartz sand to obtain a quartz crucible, wherein the mass ratio of quartz sand particles with a density greater than the third density of 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 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 of the amorphous quartz sand and the heavy liquid separation measurement method are the same as the foregoing, they are not described here again.

[0138] More specifically, the melting using the quartz sand material containing the amorphous quartz sand to obtain the quartz crucible can specifically include operation S301 to operation S302.

[0139] In operation S301, the quartz sand material is sequentially arranged in the inner layer, the middle layer, and the outer layer in the inside of the crucible mold in the direction from the outside to the inside to obtain a green body of the quartz crucible, and the average particle size 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 increases in sequence.

[0140] In operation S302, the green body of the quartz crucible is subjected to arc melting to obtain the quartz crucible, so that the quartz crucible includes the inner layer, the middle layer, and the 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; and 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 the amorphous quartz sand.

[0141] Based on the amorphous quartz sand material provided in the present application, since the quality of the amorphous quartz sand material has high consistency after being controlled by the density distribution, in the preparation process of the quartz crucible, the bubble content of the quartz crucible can be effectively avoided to be too high, or impurity points, white spots, etc. can be effectively avoided to be generated, so that the quartz crucible cannot be prepared.

[0142] According to the embodiments of the present application, in operation S301, the arrangement of the inner layer, the middle layer, and the outer layer is the same as the foregoing, and the selection of the crucible mold and the selection of the green body forming method can be the same as the preparation method of the green body of the quartz crucible, which is not described here again.

[0143] According to the embodiments of the present application, in operation S302, the operation of arc melting can include inserting the electrode into the formed green body after the electrode is started to arc, so that the electrode is quickly melted into the molten quartz in the shape of the crucible. The operation of arc melting is performed under vacuum conditions, and vacuum is drawn from the inner layer to the outer layer, so that the bubble content gradually increases from the inner layer to the outer layer, thereby improving the quality of the quartz crucible.

[0144] The present application is further illustrated by the following examples and related test experiments and results. In the following detailed description, many specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, that one or more embodiments can be practiced without these specific details. In other instances, well-known methods have not been described in detail in order to not unnecessarily obscure the present application.

[0145] It should be noted that the following specific examples are only illustrative, and the scope of protection of the present application is not limited thereto. The chemicals and raw materials used in the following examples are commercially available or self-made by conventional methods.

[0146] Crystalline quartz sand and amorphous synthetic quartz sand

[0147] (1) Selection of quartz sand

[0148] Eight kinds of quartz sand were selected for testing, including:

[0149] Crystalline quartz sand 1: the second density of the crystalline quartz sand was 2.656 g / cm 3 , the first density was 2.644 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 0.48%.

[0150] Crystalline quartz sand 2: the second density of the crystalline quartz sand was 2.653 g / cm 3 , the first density was 2.635 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 1%.

[0151] Crystalline quartz sand 3: the second density of the crystalline quartz sand was 2.648 g / cm 3 , the first density was 2.638 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 1.45%.

[0152] Crystalline quartz sand 4: the second density of the crystalline quartz sand was 2.635 g / cm 3 , the first density was 2.629 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 3.45%.

[0153] Crystalline quartz sand 5: the second density of the crystalline quartz sand was 2.621 g / cm 3 , the first density was 2.613 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 8.00%.

[0154] Crystalline quartz sand 6: the second density of the crystalline quartz sand was 2.625 g / cm 3 , the first density was 2.621 g / cm 3 , and the mass fraction of quartz sand particles less than or equal to the first density was 3%.

[0155] Crystalline quartz sand 7: the second density of the crystalline quartz sand was 2.635 g / cm 3 , the first density was 2.619 g / cm3 The mass percentage of quartz sand particles less than or equal to the first density is 10%.

[0156] Amorphous synthetic quartz sand 8: the second density of the amorphous synthetic quartz sand is 2.20 g / cm 3 The first density is 2.114 g / cm 3 The mass percentage of quartz sand particles less than or equal to the first density is 3%.

[0157] (2) Preparation of the quartz crucible body

[0158] In the direction from outside to inside, the above-mentioned crystalline quartz sand 1-7 and amorphous synthetic quartz sand 8 are prepared into inner layer quartz sand material, middle layer quartz sand material and outer layer quartz sand material according to actual needs in a vacuum environment; and in the process of being prepared into inner layer quartz sand material, middle layer quartz sand material and outer layer quartz sand material, the particle size of the crystalline quartz sand 1-7 and the amorphous synthetic quartz sand 8 satisfies that the mass percentage of quartz sand particles with a particle size of 75-150 μm in the inner layer quartz sand material is greater than or equal to 75%, the mass percentage of quartz sand particles with a particle size greater than 150 μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a particle size less than 75 μm is less than or equal to 15%; the mass percentage of quartz sand particles with a particle size of 75-150 μm in the middle layer quartz sand material is greater than or equal to 75%, the mass percentage of quartz sand particles with a particle size greater than 150 μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a particle size less than 75 μm is less than or equal to 15%; and the mass percentage of quartz sand particles with a particle size of 150-212 μm in the outer layer quartz sand material is greater than or equal to 35%, the mass percentage of quartz sand particles with a particle size greater than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size less than 110 μm is less than or equal to 15%.

[0159] Finally, the inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material are sequentially arranged in the inner part of the crucible mold to obtain the body of the quartz crucible. The inner layer quartz sand material, the middle layer quartz sand material and the outer layer quartz sand material constitute the total quartz sand material, the mass percentage of the inner layer quartz sand material in the total quartz sand material is 20%, the mass percentage of the middle layer quartz sand material in the total quartz sand material is 40%, and the mass percentage of the outer layer quartz sand material in the total quartz sand material is 40%. The above-mentioned eight kinds of quartz sand are arranged in different positions of the quartz body in different proportions, and the quartz bodies of Examples 1-6 and Comparative Examples 1-3 shown in Table 1 are obtained.

[0160] (3) Preparation of the quartz crucible

[0161] The body of the quartz crucible is arc melted, specifically, the crucible mold is vacuumized from inside to outside to form a vacuum environment, the electrode is inserted into the shaped body after arcing to quickly melt into a molten quartz in the shape of the crucible, and a quartz crucible with a transparent inner layer and an opaque outer layer is obtained.

[0162] (4) Measurement of the pass rate of the quartz crucible

[0163] The pass rate of the quartz crucible is calculated according to the requirements of impurities and light transmittance. Specifically, the bubbles, impurity points and white spots in the quartz crucible are observed by using 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. In addition, the breakage rate of the quartz crucible using these batches during the single crystal silicon pulling process is recorded. The calculation method of the breakage rate is the total number of breakages from the beginning of crystal pulling to the end / the total number of crystal pulling. The final melting pass rate and breakage rate are shown in Table 1.

[0164] Table 1

[0165] According to the results in Table 1, the inner layer, middle layer and outer layer quartz sand materials used in Example 1 all meet the density distribution requirements of the crystalline quartz sand of the present application, and the melting pass rate reaches 97% and the breakage rate reaches 10%, which shows that the crystalline quartz sand based on the density distribution requirements of the present application can be controlled at a higher quality, thereby being beneficial to improving the quality of the prepared quartz crucible and showing better melting pass rate and crystal pulling effect.

[0166] The crystalline quartz sand selected in Examples 2-3 respectively meets the density distribution requirements of the present application, only the quality of the crystalline quartz sand of the middle layer and outer layer quartz sand material is lower than the second density of Example 1. Although the melting pass rate and breakage rate of Examples 2 and 3 are slightly lower than those of Example 1, the preparation cost of the quartz crucible will be lower due to the use of the middle layer or outer layer quartz sand with lower second density. Therefore, if the melting effect, crystal pulling effect and cost are considered, Example 3 is the most preferred, and Example 2 is the second.

[0167] The crystalline quartz sand selected in Examples 4-5 respectively meets the density distribution requirements of the present application, only the second density of the inner layer quartz sand material is less than the second density of the middle layer and / or outer layer quartz sand material, and it is found that the melting pass rate and breakage rate are both deteriorated, especially the breakage rate is significantly increased.

[0168] In Example 6, the amorphous synthetic quartz sand is selected as the inner layer quartz sand material instead of the crystalline quartz sand based on Example 2, although the breakage rate of the melted quartz crucible is slightly increased, but the amorphous quartz sand selected according to the present application can be used as the inner layer quartz sand material.

[0169] By comparing Example 1 with Comparative Examples 1-3, it can be seen that when the density distribution requirements are not met, for example, in Comparative Example 1, both the second density and the mass percentage of 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 percentage of low-density quartz sand particles is too high, the melting qualified rate is significantly reduced, and it cannot be used for the preparation of crucibles at all.

[0170] Amorphous quartz sand

[0171] (1) Selection of quartz sand

[0172] Eight kinds of amorphous quartz sand were selected for testing, wherein:

[0173] Quartz sand 1: The third density of this quartz sand is 2.2208 g / cm 3 , the second density is 2.2187 g / cm 3 , the mass percentage of quartz sand particles greater than 2.2208 g / cm 3 is 4%, and the mass percentage of quartz sand particles equal to the second density is 95%. The mass percentage of particles with a particle size of 250 μm-330 μm is 40%, and the mass percentage of particles with a particle size of 330 μm-430 μm is 60%.

[0174] Quartz sand 2: The third density of this quartz sand is 2.2206 g / cm 3 , the second density is 2.2186 g / cm 3 , and the first density is 2.2066 g / cm 3 . The mass percentage of quartz sand particles greater than or equal to 2.2206 g / cm 3 is 1.0%, the mass percentage of quartz sand particles less than 2.2066 g / cm 3 is 0.50%, the mass percentage of quartz sand particles equal to the second density is 98.5%, the mass percentage of particles with a particle size of 250 μm-330 μm is 40%, and the mass percentage of particles with a particle size of 330 μm-430 μm is 60%.

[0175] Quartz sand 3: The third density of this quartz sand is 2.2204 g / cm 3 , the second density is 2.2186 g / cm 3 , and the first density is 2.2053 g / cm 3 . The mass percentage of quartz sand particles greater than or equal to 2.2204 g / cm 3 is 1.2%, the mass percentage of quartz sand particles less than 2.2053 g / cm 3The 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%. Quartz sand with a particle size of 250μm to 330μm accounts for 8%, and quartz sand with a particle size of 330μm to 430μm accounts for 92%.

[0176] Quartz sand 4: The third density of quartz sand is 2.22 g / cm³. 3 The second density is 2.2188 g / cm³. 3 The first density is 2.2089 g / cm³. 3 ≥2.22 g / cm³ 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 equals the mass percentage of quartz sand particles with the second highest density of 98.7%. Quartz sand particles with a diameter of 250μm to 325μm account for 45%, and quartz sand particles with a diameter of 330μm to 430μm account for 55%.

[0177] Quartz sand 5: The third density of quartz sand is 2.221 g / cm³. 3 The second density is 2.219 g / cm³. 3 The first 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. 3 The 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%.

[0178] Quartz Sand 6: The third 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%. Quartz sand with a particle size of 250μm to 330μm accounts for 44%, and quartz sand with a particle size of 330μm to 430μm accounts for 56%.

[0179] Quartz Sand 7: The third density of quartz sand is 2.5406 g / cm³. 3 The second density is 2.2246 g / cm³. 3 ≥2.5406 g / cm³ 3The mass ratio of quartz sand particles with a particle size of 250 μm to 330 μm is 41%, and the mass ratio of quartz sand particles with a particle size of 330 μm to 430 μm is 59%.

[0180] Quartz sand 8: the third density of the quartz sand is 2.5022 g / cm 3 , the second density is 2.3024 g / cm 3 , and the mass ratio of quartz sand particles greater than or equal to 2.5022 g / cm 3 is 14%, and the mass ratio of quartz sand particles equal to the second density is 86.00%. The mass ratio of quartz sand particles with a particle size of 250 μm to 330 μm is 43%, and the mass ratio of quartz sand particles with a particle size of 330 μm to 430 μm is 57%.

[0181] Two kinds of quartz sand obtained by sorting after being purchased on the market (high-purity natural crystalline quartz sand produced by the company, the purity of SiO2 is greater than 99.998%, and the impurity content is less than 20ppma) are selected, wherein:

[0182] Quartz sand 9: the mass ratio of quartz sand with a particle size less than 175 μm is less than or equal to 15%, and the mass ratio of quartz sand with a particle size of 175 μm to 250 μm is greater than or equal to 75%.

[0183] 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 to 425 μm is less than or equal to 63%.

[0184] (2) Preparation of quartz crucible blank

[0185] In the direction from outside to inside, the outer layer, the middle layer and the inner layer are sequentially arranged in the inside of the crucible mold in a vacuum environment to obtain the blank of the quartz crucible.

[0186] The quartz sand material of the outer layer, the quartz sand material of the middle layer and the quartz sand material of 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 material of the outer layer, the quartz sand material of the middle layer and the quartz sand material of the inner layer are prepared from natural quartz sand and / or amorphous quartz sand according to the respective conditions. In this application, the above-mentioned eight different amorphous quartz sands and two natural quartz sands are arranged in different proportions at different positions of the quartz blank, and the following Table 2 shows Examples 1-6 and Comparative Examples 1-3.

[0187] (3) Preparation of quartz crucible

[0188] The body of the quartz crucible is arc melted, specifically, the crucible mold is vacuumized from inside to outside to form a vacuum environment, the electrode is inserted into the shaped body after arcing, and the body is quickly melted into a crucible-shaped molten quartz, 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 transparent inner layer and opaque outer layer is obtained.

[0189] (4) Measurement of the pass rate of the quartz crucible

[0190] The pass rate of the quartz crucible is calculated according to the requirements of impurities and light transmittance, and the test method and test standard of the pass rate is to observe the bubbles, impurity points and white spots in the quartz crucible by using 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 crucible melting pass rate is shown in Table 2.

[0191] Table 2 Composition of the quartz body and crucible melting pass rate data in Examples 7-13 and Comparative Examples 4-6

[0192] Table 2 is the composition of the quartz body and the crucible melting pass rate data of Examples 7-12 and Comparative Examples 4-6. From Table 2, (1) in Example 7, part of the quartz sand in the outer layer uses amorphous quartz sand meeting the density distribution requirements of the present application, and the crucible melting pass rate can reach 60%. In Examples 8-9, the quality of amorphous quartz sand is further optimized, and the melting pass rate is further improved, which can reach 70%-95%. Especially, the melting pass rate of Example 8 can even be better than the melting pass rate of 93%-94% using all natural quartz sand. (2) By comparing Examples 7-8 and Comparative Examples 4-6, it can be seen that when the predetermined density range is not met, for example, in Comparative Example 4, the proportion of quartz sand particles with the second density that is too small and greater than the third density is too large; in Comparative Example 5, the proportion of quartz sand particles greater than the third density is too large and the difference between the third density and the second density is too large; in Comparative Example 6, the mass proportion of quartz sand particles greater than the third density is too high, which makes it difficult to control the quality of amorphous quartz sand, and ultimately leads to the failure of crucible melting. (3) In Example 9, the particle size distribution of the selected amorphous quartz sand is not within the range of amorphous quartz sand, although it can successfully melt the quartz crucible, but compared with the melting pass rate of Example 7, which decreases from 93% to 70%, it is speculated that this is because the particle size distribution range affects the bubble content in the crucible, and too high bubble content can easily lead to a decrease in the pass rate. (4) In Examples 10-11, amorphous quartz sand is used in the inner layer and middle layer quartz sand, although it can successfully melt the quartz crucible, but the pass rate decreases, it can be seen that the initially sorted quartz sand still cannot meet the high performance requirements of the inner layer and middle layer quartz sand.

[0193] The above-described specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application, and it should be understood that the above-described specific embodiments are merely for the specific embodiments of the present application and are not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A quartz sand having an alpha-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 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 .

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

4. 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%.

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

6. A synthetic quartz sand in an amorphous state, a mass ratio of quartz sand particles having a second density of not more than 4%, the quartz sand having a second density of not less than 2.2 g / cm3 and less than 2.3 g / cm3. 3 3 .​ 7. The quartz sand of claim 6, 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%.

8. The quartz sand of claim 6, wherein, The impurity content of the quartz sand is less than or equal to 20 ppm.

9. A quartz sand, which is an amorphous quartz sand, the mass fraction of quartz sand particles greater than a third 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 fraction of quartz sand particles equal to the second density is greater than 91%, preferably greater than 95%, more preferably greater than 97%.

10. The quartz sand of claim 9, wherein, The mass percentage of quartz sand particles less than the first density is not more than 1%.

11. The quartz sand of claim 9, wherein, the difference between the second density and the third density is greater than or equal to 0.001 g / cm 3 and less than 0.3 g / cm 3 .

12. The quartz sand of claim 9, wherein, The impurity content of the amorphous quartz sand is less than or equal to 30 ppm.

13. The quartz sand of claim 9, wherein, 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-250 μm is more than or equal to 75%; Or, the mass percentage of quartz sand particles with a particle size of 250 μm-325 μm is more than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 325 μm-425 μm is less than or equal to 63%; Or, the mass percentage of quartz sand particles with a particle size of 250 μm-330 μm is more than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 330 μm-430 μm is less than or equal to 63%.

14. The quartz sand of claim 9, wherein, The mass percentage of quartz sand particles more than the third density is not more than 5%.

15. The quartz sand of any one of claims 1-14, wherein, the difference between the second density and the first density is greater than or equal to 0.001 g / cm3 3 .

16. A body of a quartz crucible prepared from the quartz sand according to any one of claims 1-15.

17. The body of a quartz crucible according to claim 16, wherein, The body of the quartz crucible comprises an inner layer of quartz sand material, a middle layer of quartz sand material and an outer layer of quartz sand material along a direction from inside to outside, The inner layer of quartz sand material, the middle layer of quartz sand material and the outer layer of quartz sand material are respectively selected from the quartz sand according to any one of claims 1-5, 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.

18. The body of a quartz crucible according to claim 17, 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.

19. The body of a quartz crucible according to claim 17, 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 .

20. The body of a quartz crucible according to claim 17, wherein, The mass percentage of the inner layer quartz sand in the total mass of the body of the quartz crucible is 10% to 30%, the mass percentage of the middle layer quartz sand in the total mass of the body of the quartz crucible is 20% to 45%, and the mass percentage of the outer layer quartz sand in the total mass of the body of the quartz crucible is 35% to 50%.

21. The body of a quartz crucible according to claim 16, wherein, The body of the quartz crucible comprises an inner layer quartz sand, a middle layer quartz sand and an outer layer quartz sand in a direction from inside to outside, wherein the inner layer quartz sand is selected from the quartz sand of any one of claims 6-8.

22. The body of a quartz crucible according to claim 21, wherein, The mass percentage of the inner layer quartz sand in the total mass of the body of the quartz crucible is 10% to 30%, the mass percentage of the middle layer quartz sand in the total mass of the body of the quartz crucible is 20% to 45%, and the mass percentage of the outer layer quartz sand in the total mass of the body of the quartz crucible is 35% to 50%.

23. The body of a quartz crucible according to claim 16, wherein, The mass percentage of the amorphous quartz sand in the body of the quartz crucible is 10% to 30% according to any one of claims 9-14.

24. The body of a quartz crucible according to claim 23, wherein, The body of the quartz crucible comprises an inner layer, a middle layer and an outer layer in a direction from inside to outside; The inner layer quartz sand contains the 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 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%; and / or, The middle layer quartz sand contains the amorphous quartz sand, and the amorphous quartz sand in the middle 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 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%; or, the amorphous quartz sand in the middle layer is defined as second amorphous quartz sand, and in the second amorphous quartz sand, the mass percentage of quartz sand particles with a particle size of 250 μm to 325 μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 325 μm to 425 μm is less than or equal to 63%; and / or, The outer layer quartz sand contains the 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 250 μm to 330 μm is greater than or equal to 37%, and the mass percentage of quartz sand particles with a particle size of 330 μm to 430 μm is less than or equal to 63%.

25. A body for a quartz crucible according to any one of claims 16 to 24, wherein, The average particle size of the quartz sand of the inner layer quartz sand, the middle layer quartz sand and the outer layer quartz sand increases in turn.

26. The body of the quartz crucible according to claim 25, wherein: when the inner layer quartz sand, the middle layer quartz sand or the outer layer quartz sand is selected from the quartz sand of any one of claims 1-5; or, the inner layer quartz sand is selected from the quartz sand of any one of claims 6-8; the quartz sand of the inner layer quartz sand material has a particle size of 75-150 μm, the mass percentage of quartz sand particles with a particle size of 75-150 μm is greater than or equal to 75%, the mass percentage of quartz sand particles with a particle size of 150-212 μm is less than or equal to 5%, and the mass percentage of quartz sand particles with a particle size less than 75 μm is less than or equal to 15%; and / or the quartz sand of the middle layer quartz sand material has a particle size of 150-212 μm, the mass percentage of quartz sand particles with a particle size of 150-212 μm is greater than or equal to 40%, the mass percentage of quartz sand particles with a particle size greater than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size less than 110 μm is less than or equal to 12%; and / or the quartz sand of the outer layer quartz sand material has a particle size of 150-212 μm, the mass percentage of quartz sand particles with a particle size of 150-212 μm is greater than or equal to 35%, the mass percentage of quartz sand particles with a particle size greater than 212 μm is less than or equal to 45%, and the mass percentage of quartz sand particles with a particle size less than 110 μm is less than or equal to 15%.

27. A quartz crucible prepared using the body of the quartz crucible according to any one of claims 16-26.

28. A method for preparing a quartz crucible, comprising: melting using the quartz sand according to any one of claims 1-5 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 .

29. A method for preparing a quartz crucible, comprising: melting using the quartz sand according to any one of claims 6-8 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 .

30. A method for preparing a quartz crucible, comprising: melting using the quartz sand according to any one of claims 9-14 to obtain the quartz crucible; The mass ratio of the quartz sand particles with the third 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%.

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