CN220927019U - Combined crucible for pulling single crystal bar by single crystal furnace - Google Patents
Combined crucible for pulling single crystal bar by single crystal furnace Download PDFInfo
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- CN220927019U CN220927019U CN202321636654.4U CN202321636654U CN220927019U CN 220927019 U CN220927019 U CN 220927019U CN 202321636654 U CN202321636654 U CN 202321636654U CN 220927019 U CN220927019 U CN 220927019U
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- Crystals, And After-Treatments Of Crystals (AREA)
Abstract
The utility model relates to a combined crucible for pulling a single crystal bar by a single crystal furnace. The combined crucible is provided with an inner crucible (1), an outer crucible (2) and an intermediate packing layer (3) which are resistant to high Wen Juyi heat conduction; the inner crucible (1) is arranged in the outer crucible (2), and a gap serving as a filling gap (4) is reserved between the inner crucible and the outer crucible. The inner crucible (1) comprises a high temperature resistant protective layer (12) and a crucible main body (11) which is a homogeneous integral piece. The high-temperature resistant protective layer (12) is a coating and is covered and fixed on the inner wall of the crucible main body (11), so as to play a role in sealing the inner wall of the crucible main body (11). The intermediate packing layer (3) is an aggregate of solid particles, is disposed in the packing gap (4) and is plugged between the inner crucible (1) and the outer crucible (2), so that the inner crucible (1) and the outer crucible (2) are tightly fitted together by the intermediate packing layer (3) and constitute an integral assembly.
Description
Technical Field
The present utility model relates to an apparatus for pulling a silicon single crystal rod, and more particularly, to a combination crucible of a single crystal furnace for pulling a silicon single crystal rod.
The single crystal rod is a short term of a single crystal silicon rod. Molten silicon is also known as liquid silicon, molten silicon, or silicon melt.
Background
Solar photovoltaic power generation is the cleanest new energy at present, and has good development prospect. The main parts of the solar photovoltaic power generation device are a bracket and a solar panel, and the panels are mainly monocrystalline silicon panels and polycrystalline silicon panels, and currently are mainly monocrystalline silicon panels. The main body of the monocrystalline silicon battery plate is made of monocrystalline rods, and the main cost for manufacturing the monocrystalline rods is mainly quartz crucible, thermal field, electricity cost and labor except silicon material. Wherein the quartz crucible accounts for a large proportion of the total drawing cost of the single crystal rod.
The conventional combined crucible for pulling a single crystal rod is configured by providing an outer crucible (graphite crucible or carbon crucible) to the outer portion of a quartz crucible located at an inner layer. The quartz crucible mainly plays roles of loading and preventing leakage, and the outer crucible mainly plays a role of supporting. Because the quartz crucible and the outer layer crucible cannot be tightly matched, a certain gap exists, when the silicon material is heated to 1350 ℃, the quartz crucible begins to soften, the gap between the quartz crucible and the outer layer crucible is filled with the silicon material along with the rising of the temperature, and the quartz crucible and the outer layer crucible are tightly attached together after the temperature is high. The quartz crucible plays a role in melting silicon materials and preventing leakage, and the outer crucible plays a role in supporting and protecting. The disadvantage of such a combination crucible is that the quartz crucible reacts with the liquid silicon at high temperature to form silicon monoxide and free oxygen, some of which enters the pulled single crystal silicon rod, causing an increase in its oxygen content, which adversely affects the conversion efficiency of the cell, and the combination crucible is a device which in use reduces the quality of the single crystal rod.
Chinese patent document CN202643902U (chinese patent application No. 201220192925.7, hereinafter referred to as document 1) discloses a single crystal furnace graphite crucible lifting device. The device comprises a split graphite crucible serving as an outer crucible, a graphite crucible serving as an inner crucible and a graphite crucible tray serving as a support for the split graphite crucible. In the background art, document 1 indicates that "single crystal silicon is generally produced by the CZ method". The CZ method is to dissolve raw material silicon in a graphite crucible by means of a heater, and then immerse a seed crystal mounted on a seed crystal chuck in the solution. According to the CZ method, the raw material silicon should not be dissolved but should be melted, and in addition, the seed crystal is immersed in the melt instead of the solution. After the correction, if the graphite crucible is used for melting the silicon material, first, since the graphite crucible is obtained by sintering graphite powder through hot isostatic pressing, a certain gap exists, so that liquid silicon permeates into the graphite internal gap of the graphite crucible, and when the single crystal furnace is cooled down, the graphite crucible bursts due to the effect of thermal expansion and cold contraction. And a certain gap is formed between the second graphite crucible and the split graphite crucible, so that a good supporting and protecting effect cannot be achieved, namely, the stability is poor. Therefore, the graphite crucible of document 1 has no practical applicability.
Disclosure of Invention
The utility model aims to provide a combined crucible for pulling a single crystal silicon rod by a single crystal furnace, which is free from infiltration in a state of storing molten silicon, long in service life and good in stability.
The technical scheme for realizing the aim of the utility model is as follows: the combined crucible for pulling the single crystal bar by the single crystal furnace provided by the utility model has a high-temperature-resistant inner crucible and a high-temperature-resistant outer crucible. The outer crucible is an integral structural member. The inner crucible is disposed in the outer crucible. The structure is characterized in that: also has an intermediate filler layer which is high temperature resistant and has better heat conductivity. The inner crucible comprises a high-temperature resistant protective layer (called protective layer for short) and a high-temperature resistant crucible main body (also called inner crucible main body) of a homogeneous integral piece. The high-temperature resistant protective layer is a coating and is fixedly arranged on the inner wall of the crucible main body in a covering manner, so that the inner wall of the crucible main body is closed. A gap serving as a filling gap is reserved between the inner crucible and the outer crucible. The intermediate packing layer is an aggregate of solid particles disposed in the packing gap and is tightly packed between the inner crucible and the outer crucible, so that the inner crucible and the outer crucible are tightly fitted together through the intermediate packing layer to form an integral assembly.
In the above-mentioned embodiments, the thermal conductivity of the intermediate filler layer preferably means that the thermal conductivity of the material is 10W/mK or more. The inner crucible is used for containing liquid silicon and the like, the melting point of the silicon is 1410 ℃, and the high temperature resistance of the inner crucible means that the material of the inner crucible has the functions of not decomposing and not softening at the working temperature of 1600 ℃. Therefore, the material of the crucible body is preferably graphite, silicon carbide, silicon nitride or boron nitride, that is, the crucible body may preferably be a silicon carbide crucible, a silicon nitride crucible, a graphite crucible or a boron nitride crucible, which have melting points of 2700 ℃, 1900 ℃, 3527 ℃ and 2700 ℃ in this order, and corresponding operating temperatures of 1800 ℃, 1650 ℃, 1800 ℃ and 1800 ℃, respectively. The high temperature resistant protective layer may preferably be a silicon carbide coating, a silicon nitride coating, a graphite coating, or a boron nitride coating, all of which also operate at temperatures of 1650 ℃ and above. Therefore, when the single crystal furnace performs the operation of drawing the single crystal silicon rod (including holding the liquid silicon material), the crucible body of the inner crucible and the high temperature resistant protective layer are stable and durable and do not soften or melt. That is, when the inner crucible in the scheme is used for containing liquid silicon materials, the filling gaps cannot disappear due to deformation of the inner crucible caused by temperature rise in use.
In the scheme, the materials of the crucible main body and the high-temperature-resistant protective layer are selected in principle that the crucible main body and the high-temperature-resistant protective layer are not deformed at the melting temperature of the simple substance silicon, so that a filling gap between the inner crucible and the outer crucible cannot disappear. If no corresponding measures are adopted, the supporting and protecting effects of the outer crucible on the inner crucible can not be effectively exerted due to the existence of the filling gaps, namely, the problem of movement stability of the inner crucible caused by unstable supporting exists under the condition that an intermediate filling layer is not arranged. The arrangement of the intermediate packing layer effectively solves the stability problem of the inner crucible during rotary motion. The solid particles forming the intermediate packing layer are filled and plugged in the packing gap between the inner crucible and the outer crucible, so that the inner crucible and the outer crucible are integrated and rotate together with the outer crucible, and after the heat of the thermal field is transferred to the outer crucible in a heat radiation manner, the outer crucible can be conveniently transferred to the inner crucible in a heat conduction manner through the intermediate packing layer, thereby heating or preserving the heat of the silicon material in the inner crucible.
In the scheme, when the crucible main body is preferably a silicon carbide crucible, a silicon nitride crucible, a graphite crucible or a boron nitride crucible, the graphite crucible is a directly sintered isostatic pressure graphite product, preferably a directly sintered hot isostatic pressure graphite product, and is mainly formed by processing high-purity graphite, has the characteristics of high-purity graphite, has the main characteristics of small thermal expansion rate, excellent thermal conductivity after being heated and the like, and has the thermal conductivity coefficient of 151W/m.K. The silicon carbide crucible is a directly sintered isostatically molded silicon carbide crucible, preferably a directly sintered hot isostatic molded silicon carbide crucible having a thermal conductivity of 150W/mK to 200W/mK. The silicon nitride crucible is also a directly sintered isostatically molded silicon nitride crucible, preferably a directly sintered hot isostatic molded silicon nitride crucible having a thermal conductivity of 30W/m·k to 120W/m·k. The boron nitride crucible is prepared by adopting a hot press molding method, and the heat conductivity coefficient of the boron nitride crucible is 24W/m.K to 200W/m.K. The crucible main body made of the material has a certain internal pore when in molding. In the scheme, the inner wall of the crucible main body of the inner crucible is provided with the high-temperature-resistant protective layer, and the high-temperature-resistant protective layer plays a role in sealing the inner wall of the crucible main body, so that when liquid silicon is contained, the liquid silicon cannot permeate into the inside of the material of the crucible main body, and the safety of the inner crucible serving as a crystal pulling container is ensured.
In the scheme, the solid particles of the middle packing layer can be uniformly dispersed in the packing gaps in a vibration mode, and the distribution is favorable for the tight fit of the inner crucible and the outer crucible.
Furthermore, in the combined crucible for pulling the single crystal rod by the single crystal furnace, the inner crucible sequentially comprises a pot side section, a transition section and a pot bottom from top to bottom, and the thicknesses of the parts are basically the same. The inner crucible is located and attached to the outer crucible from the bottom of the pot, and corresponding gaps reserved between the outer walls of the upper section and the transition section of the inner crucible and the inner wall of the outer crucible are filler gaps. The width d of the filling gap refers to the interval between the outer wall of the side section of the inner crucible and the inner wall of the outer crucible, and the interval d is 2.1 mm to 15 mm. The solid particles of the intermediate filler layer are 10 mesh to 20 mesh in size.
In the scheme, the bottom of the inner crucible is basically attached to the outer crucible, and no gap exists between the inner crucible and the outer crucible. Gaps are reserved between the pot side sections of the inner crucible and the positions, corresponding to the transition sections and the outer crucible, of the pot side sections are basically consistent with the outer crucible in size, and the gaps between the transition sections and the outer crucible are gradually reduced from top to bottom until the gaps are zero.
In the above-described variant, the width d of the filling gap corresponds to the radial length of the intermediate filling layer, i.e. the thickness of the peripheral part of the intermediate filling layer, for the intermediate filling layer arranged at the pot upper section. For the middle filler layer, the solid particles corresponding to 10 mesh were 2mm in size and the solid particles corresponding to 20 mesh were 0.84 mm in size.
Furthermore, in the combined crucible for pulling the single crystal rod by the single crystal furnace, the size specification of solid particles of the intermediate packing layer is 16+/-1 meshes, and the width d of a packing gap is 3-10 mm.
In the above-described scheme, the particle diameter of the solid particles corresponding to 16 mesh was 1.19 mm. The size specification of the solid particles is preferably 16+ -1 mesh, and the width d of the filling gap is preferably 3 mm to 10 mm, so that the packing of the solid particles in the filling gap is easier to carry out. The material of the intermediate packing layer is preferably silicon carbide particles, silicon nitride particles, boron nitride particles, aluminum oxide ceramic particles or zirconium oxide ceramic particles. These solid particles do not soften or melt at 1600 c and do not chemically react to decompose. Silicon carbide is silicon carbide, and the heat conductivity coefficient of the silicon carbide is 12W/m.K to 30W/m.K. The silicon nitride has a thermal conductivity of 20W/mK to 80W/mK. The boron nitride has a thermal conductivity of 15W/mK to 45W/mK. The heat conductivity coefficient of the alumina ceramic particles is 20-30W/mK. The zirconia ceramic particles had a thermal conductivity of 30W/mK.
Further, in the combined crucible for pulling a single crystal rod by the single crystal furnace, the thickness of the crucible main body of the inner crucible is 8-15 mm, and the thickness of the high temperature resistant protective layer of the inner crucible is 1-50 microns, preferably 10-40 microns, and further preferably 5-10 microns.
In the scheme, the high-temperature-resistant protective layer plays a role in closing the inner pores on the surface of the inner wall, so that the inner crucible cannot infiltrate into the inner pores of the crucible main body of the inner crucible when liquid silicon is contained, and the safety and stability of crystal pulling are ensured.
Further, in the combined crucible for pulling the single crystal rod by the single crystal furnace, the outer crucible comprises a crucible support and a crucible side. The lower part of the crucible side is matched with the upper part of the crucible support, and the lower part and the upper part are hermetically and fixedly connected to form an integrated structural member.
In the above scheme, the material of the crucible support is preferably graphite, and the material of the crucible side is preferably a carbon/carbon composite material. The carbon/carbon composite material of the crucible side is also called as C/C composite material or carbon fiber reinforced carbon composite material. Carbon/carbon composites are typically manufactured by chemical vapor deposition, i.e., reacting carbon or a carbon source with a gas at high temperature to form carbon fibers, and depositing carbon-based atoms on the surfaces of the fibers to form the carbon/carbon composite. The carbon/carbon composite material has high temperature resistance, and the strength of the carbon/carbon composite material is not changed at high temperature close to 3000 ℃.
In the scheme, the outer crucible is manufactured by dividing the outer crucible into the crucible support and the crucible side, so that the cost can be greatly reduced, the crucible support part corresponds to the bottom of the inner crucible, and the crucible side part corresponds to the side section and the transition section of the inner crucible at the same time.
Furthermore, the combined crucible for pulling the single crystal rod by the single crystal furnace provided by the utility model is also provided with a high-temperature adhesive sinter, wherein the high-temperature adhesive sinter is sintered between the crucible side of the outer crucible and the crucible support, so that the crucible side and the crucible support are fixedly connected together, and the outer crucible is an integrated structural member.
In the above scheme, the raw materials of the high-temperature adhesive sinter comprise polyimide resin. The polyimide resin is preferably COPNA resin, and the polyimide resin is a condensed polycyclic polynuclear aromatic resin. The raw materials of the high-temperature adhesive sinter also comprise crushed carbon fibers, and the carbon fibers are used for reinforcing the high-temperature adhesive sinter. Polyimide resin accounts for 70 to 90 percent of the weight of the raw materials, and the balance is carbon fiber. In order to ensure the overall strength of the outer crucible and the stability in use, the crucible side and the crucible support are fixedly connected to achieve the function of adhesion by sintering the polyimide resin. The incorporation of 1 to 2 mm long chopped carbon fibers into the viscous polyimide resin prior to sintering greatly increases the strength of the high temperature binder sinter.
The utility model has the positive effects that: (1) Compared with the prior art, the outer crucible provided by the utility model has the advantages that firstly, the manufacturing method is simple, the process is troublesome if the outer crucible is made of a carbon/carbon composite material, and secondly, the cost of the outer crucible can be greatly reduced (by about half). And thirdly, the combined outer crucible in the prior art has no sealing treatment among the components of the outer crucible, and only the components are matched with each other, so that the outer crucible can only play a supporting role. Because of a certain gap between the components of the outer crucible, when the inner crucible is in accident and flows out of the high-temperature silicon melt, the high-temperature silicon melt can leak into the single crystal furnace through the gap, and serious silicon leakage event can be caused. At present, the silicon leakage accident of the single crystal furnace is the biggest problem, and the explosion can happen seriously. The external crucible adopts the scheme of sintering the high-temperature adhesive, the crucible support is preferably coated with the corresponding polyimide resin, the crucible sides are placed on the crucible support to be mutually combined, then the polyimide resin is used for caulking, and the crucible sides and the crucible support are carbonized at high temperature to be sintered, so that the crucible sides and the crucible support are hermetically and fixedly connected together. (2) The inner crucible of the utility model does not adopt a quartz crucible any more, so that the oxygen content in the high-temperature silicon melt is obviously reduced compared with that of the quartz crucible, and the high-temperature resistant protective layer does not react with the high-temperature silicon melt at high temperature, so that the reaction of the quartz crucible in the prior art with the high-temperature silicon melt to generate trace free oxygen is avoided, and the quality of the monocrystalline silicon rod is improved. (3) The cost of the inner crucible is obviously reduced, the quartz crucible used as the inner crucible in the prior art can only be used once, usually can only be used for drawing 5 to 7 single crystal silicon rods (about 20 days) at high temperature, and the quartz crucible can not be reused after the single crystal furnace is cooled. The combined crucible provided by the utility model can be repeatedly used, and the service life of the combined crucible can reach 1-2 years or more. In the industry, the cost of a high-purity quartz crucible used as an inner crucible seriously affects the cost of a solar photovoltaic power generation panel, and is controlled abroad, so that the constraint of the quartz crucible is eliminated, and the problem which is urgently needed to be solved currently. The combined crucible solves the problem of urgent need of the development of the restriction industry. (4) the utility model is very smart in providing the intermediate filler layer. If no intermediate filler layer is arranged, the degree of adhesion between the inner crucible and the outer crucible with the high-temperature protective inner coating is difficult to improve when the inner crucible and the outer crucible are matched, and if the crucible main body is a graphite crucible, a silicon carbide crucible, a silicon nitride crucible or a boron nitride crucible, the graphite, the silicon carbide, the silicon nitride or the boron nitride cannot soften at the high temperature of 1600 ℃, so that a filler gap between the inner crucible and the outer crucible always exists, namely the outer crucible cannot play a supporting protection role. After the intermediate packing layer is arranged, the inner crucible and the outer crucible form an integral assembly, so that the supporting and protecting effects of the outer crucible on the inner crucible are fully exerted, the outer crucible and the inner crucible are tightly fixed together in a rotating state in crystal pulling, and the outer crucible can sequentially pass through the intermediate packing layer and the inner crucible in a heat conduction mode after receiving the heat of a thermal field through heat radiation due to the fact that the materials of the intermediate packing layer are solid particles with good heat conductivity, and effective heat transfer is achieved.
Drawings
FIG. 1 is a schematic view of a structure of a combination crucible of the present utility model.
Fig. 2 is a schematic view of the inner crucible of fig. 1.
Fig. 3 is a schematic view of the structure of the side wall of the outer crucible of fig. 1.
Fig. 4 is a schematic view of the structure of a crucible support of the outer crucible of fig. 1.
Fig. 5 is a schematic structural view of the outer crucible of fig. 1.
The reference numerals in the above figures are as follows:
The high-temperature adhesive sintering material comprises an inner crucible 1, a pot upper section 1-1, a transition section 1-2, a pot bottom 1-3, a crucible main body 11, a high-temperature resistant protective layer 12, an outer crucible 2, a crucible support 21, a lower circular ring part 21-1, a lower circular platform part 21-2, a positioning mechanism 21-3, a positioning boss 21-3-1, an upper side contact surface 21-3-2, a pot upper 22, a pot upper section 22-1, a pot upper lower section 22-2, an upper circular ring part 22-2-1, an upper circular platform part 22-2-2, an intermediate filler layer 3, a filler seam 4, a filler seam width d and a high-temperature adhesive sintering material 5.
Detailed Description
Example 1
Referring to fig. 1, a combined crucible for pulling a single crystal rod in a single crystal furnace of this embodiment has a high temperature resistant inner crucible 1, a high temperature resistant outer crucible 2, a high temperature resistant intermediate filler layer 3 with good thermal conductivity, a filler gap 4, and a high temperature adhesive sinter 5. The outer crucible 2 is an integral structural member.
Still referring to fig. 1, the inner crucible 1 includes a high temperature resistant protective layer 12 and a high temperature resistant crucible body 11 of homogeneous unitary piece. The crucible body 11 is made of graphite, that is, the crucible body 11 is a graphite crucible. The high temperature resistant protective layer 12 is a coating layer which is covered and fixed on the inner wall of the crucible main body 11, and plays a role in sealing the inner wall of the crucible main body 11, and is a silicon carbide coating layer. The inner crucible 1 is arranged in the outer crucible 2 such that a gap is left between the inner crucible 1 and the outer crucible 2 as a filling gap 4.
Still referring to fig. 1, the intermediate packing layer 3 is an assembly of solid particles disposed in the packing gap 4 and packed between the inner and outer crucibles 1 and 2 such that the inner and outer crucibles 1 and 2 are tightly fitted together by the intermediate packing layer 3 to form an integral assembly.
Still referring to FIG. 1, the inner crucible 1 comprises a side section 1-1, a transition section 1-2 and a bottom section 1-3 in sequence from top to bottom, and the thicknesses of the sections are basically the same, and the values are 13+/-0.5 mm. The shape of the pot side section 1-1 is cylindrical, the outer diameter of the pot side section 1-1 is 695+/-1 mm, the height of the inner crucible 1 is 500+/-2 mm, wherein the height of the pot side section 1-1 is 319 mm, the height of the transition section is 108 mm, and the height of the crucible bottom 1-3 is 72 mm. The outer wall of the transition section 1-2 is in the shape of a spherical sector, the radius of the outer wall is 130 mm, the outer wall of the crucible bottom 1-3 is also in the shape of a spherical sector, the radius of the outer wall is 711 mm, and the transition section 1-2 and the pot bottom 1-3 are in smooth transition at the joint. The inner crucible 1 can hold 300 kg of silicon material.
Referring to fig. 1 and 4, the outer crucible 2 includes a crucible support 21 and a side wall 22. The crucible support 21 is made of graphite, and the crucible side 22 is made of carbon/carbon composite material. The average thickness of the saucer 21 is 50 mm, the overall shape of the saucer is a downwardly concave crucible bottom, the outer diameter of the saucer is 670 mm, the shape of the inner wall of the saucer 21 is a sector-shaped outer side surface, and the radius of the saucer is 708 mm. The crucible support 21 is provided with a lower circular ring part 21-1 and a lower round table part 21-2 which are positioned at the peripheral part, and the bottom of the crucible support 21 is also provided with a positioning mechanism 21-3 for positioning the combined crucible on a tray component of the single crystal furnace. The positioning mechanism 21-3 consists of a cylindrical positioning boss 21-3-1 protruding downwards and an upper contact surface positioned above the periphery of the positioning boss 21-3-2.
Referring to fig. 3, a side 22 of the outer crucible 2 is divided into a side upper portion 22-1 and a side lower portion 22-2. The upper side portion 22-1 is cylindrical in shape, has a thickness of 18 mm, and has an inner diameter of 710 mm. The inner wall of the lower part 22-2 of the boiler side is shaped as the outer side of a sphere sector, and the radius of the outer side is 140 mm. The shape of the outer wall of the lower part 22-2 of the cooker side is divided into an upper section and a lower section, the shape of the upper section of the outer wall is a cylindrical outer side surface, the shape of the lower section of the outer wall is a spherical sector-shaped outer side surface, and the radius of the lower section of the outer wall is 120 mm. The thickness of the lower part 22-2 of the pot side is gradually increased from 18 mm to 36 mm.
Referring to fig. 3 and 4, a lower side portion 22-2 of the side 22 is provided with an upper annular portion 22-2-1 and an upper circular truncated cone portion 22-2-2 at the bottom. The upper circular ring portion 22-2-1 of the lower part 22-2 of the side 22 is engaged with the lower circular ring portion 21-1 of the support 21, and the upper circular table portion 22-2-2 of the lower part 22-2 of the side 22 is engaged with the lower circular table portion 21-2 of the support 21.
Referring to fig. 1, the lower part of the crucible side 22 is matched with the upper part of the crucible support 21 through the circular ring part and the circular truncated cone part, and the circular ring part and the circular truncated cone part are hermetically and fixedly connected to form an integrated structural member. Wherein the raw materials of the high-temperature adhesive sinter 5 comprise polyimide resin and chopped carbon fibers. The carbon fibers are used to reinforce the high temperature binder sinter 5. Polyimide resin accounts for 70 to 90 percent of the weight of the raw materials, and the balance is carbon fiber. The high-temperature adhesive sinter 5 is sintered between the crucible side 22 and the crucible support 21 of the outer crucible 2, so that the crucible side 22 and the crucible support 21 are fixedly connected together, and the outer crucible 2 is an integral structure.
Still referring to fig. 1, the outer crucible 2 has a height of 530 mm, wherein the crucible side 22 has a height of 435 mm, the saucer 21 has a height of 112.5 mm, and the saucer 21 has a height of 17.5 mm stagger at the junction with the crucible side 22. The staggered height of the pan carrier 21 is removed and the nominal height of the pan carrier 21 is 95 mm.
Still referring to fig. 1, when the inner crucible 1 is disposed in the outer crucible 2, the rim section 1-1 of the inner crucible 1 corresponds in height to the rim upper portion 22-1 of the rim 22 of the outer crucible 2, the transition section 1-2 of the inner crucible 1 corresponds to the rim lower portion 22-2 of the rim 22 of the outer crucible 2, and the bottom 1-3 of the inner crucible 1 corresponds to the crucible support 21 of the outer crucible 2. The radius of the inner wall of the pot support 21 is slightly smaller than the radius 711 mm of the outer wall of the crucible bottom 1-3 of the inner crucible 1, and when the inner crucible 1 is placed, the inner crucible is stably located, and the relationship between the inner crucible 1 and the pot support 21 is basically fit with the crucible bottom 1-3 of the inner crucible 1.
Still referring to fig. 1, a gap exists between the inner crucible 1 and the outer crucible 2. The gap between the outer wall of the side section 1-1 of the inner crucible 1 and the inner wall of the side upper portion 22-1 of the outer crucible 2 is substantially the same; the gap between the transition section 1-2 of the inner crucible 1 and the crucible side lower portion 22-2 of the crucible side 22 of the outer crucible 2 gradually decreases from top to bottom until zero; the bottom 1-3 of the inner crucible 1 and the crucible support 21 of the outer crucible 2 are in a basically attached state, so that no gap exists between the two.
Still referring to FIG. 1, the width d of the filling slit 4 refers to the distance between the outer wall of the side section 1-1 of the inner crucible 1 and the inner wall of the side upper portion 22-1 of the outer crucible 2, which in this embodiment is 7.5.+ -. 1mm.
Still referring to fig. 1, the intermediate packing layer 3 is an aggregate of solid particles disposed in the packing gap 4 and packed between the inner crucible 1 and the outer crucible 2 such that the inner crucible 1 and the outer crucible 2 are tightly fitted together by the intermediate packing layer 3 to constitute an integral assembly. Wherein the thickness (i.e., radial length) of the intermediate packing layer 3 between the side section 1-1 of the inner crucible 1 and the side upper portion 22-1 of the side 22 of the outer crucible 2 is 7.5 mm as the width of the packing slit 4. The thickness of the intermediate packing layer 3 between the transition section 1-2 of the inner crucible 1 and the side lower portion 22-2 of the side 22 of the outer crucible 2 is gradually reduced from 7.5 mm to zero.
Referring to fig. 2, the crucible body 11 of the inner crucible 1 of the present embodiment is a graphite crucible manufactured by a hot isostatic pressing method, and can withstand high temperatures up to 1800 ℃. The hot isostatic pressing process is a process commonly used in the art for preparing graphite crucibles.
The first method for manufacturing the graphite crucible body 11 by hot isostatic pressing is as follows: firstly, raw materials are prepared. High purity natural graphite or artificial graphite powder, a binder and a lubricant are uniformly mixed to form a compressible graphite blank. And secondly, pressing into a blank. Loading a graphite blank into a mold, wherein the shape of the mold can be determined according to the shape of the graphite crucible main body 11 to be prepared; and then pressed under high pressure to form a graphite blank having a certain shape and density. Thirdly, heat treatment. And carrying out heat treatment on the graphite blank at a certain temperature and pressure to ensure that the structure is more compact, and the strength and the hardness of the graphite blank are increased to form a solid graphite blank. Fourthly, machining. The heat treated solid graphite body is machined (e.g., cut, drilled, ground, etc.) to achieve the desired shape and size. Fifthly, hot isostatic pressing. After the machining is completed, the graphite blank is placed in a high-pressure container, and isostatic pressing treatment is performed at a certain temperature and pressure, that is, a treatment mode of high-temperature sintering under high pressure is adopted, so that the solid graphite blank is sintered into the graphite crucible main body 11. The method not only ensures that the density is more compact and the internal defects are reduced, thereby prolonging the service life and improving the high temperature resistance.
The second method of manufacturing the graphite crucible body 11 by the hot isostatic pressing method is as follows: adding graphite powder into the mixture, and uniformly stirring to form slurry; pouring the slurry into a crucible type (a mold referring to a graphite crucible matrix), and vibrating the slurry in a vacuum environment; the crucible after compaction is placed in a hot isostatic press, high pressure is applied, the temperature is raised, the heat is preserved, the temperature is lowered, and the pressure is relieved, so that a semi-finished product of the high-density graphite crucible main body 11 is obtained. And then subjected to related mechanical processing such as polishing and the like, to obtain the graphite crucible body 11. The method directly adopts the hot isostatic pressing method to prepare the graphite crucible main body 11, so that the crucible has the advantages of uniform density, higher density, better thermal stability, longer service life and lower cost. The second method is preferred in this embodiment.
The hot isostatic pressing method has the advantages that the product with the characteristics of complex shape, accurate size, uniform density, excellent mechanical property, smooth surface layer and the like can be prepared. Meanwhile, as the compression conditions are strictly controlled, the internal structure and physical properties of the graphite crucible can be ensured to be uniform, so that the graphite crucible has higher quality stability.
Still referring to fig. 2, a high temperature resistant protective layer 12 is provided on the inner wall of the crucible body 11 of the inner crucible 1. The high temperature resistant protective layer 12 is a silicon carbide film having a thickness of 10 micrometers to 50 micrometers. The silicon carbide film is obtained by adopting an MOCVD method (belonging to the prior art), namely a metal organic chemical vapor deposition method, and is a method for sublimating a metal organic compound into metal vapor under a certain temperature condition in vacuum or inert atmosphere and then reacting with other gases to form a solid material. The MOCVD method for forming the silicon carbide coating on the inner wall surface of the graphite crucible comprises the following specific steps: firstly, cleaning the surface of the inner wall of a graphite crucible, removing impurities and dust, and placing the graphite crucible in a vacuum furnace for deoxidizing treatment to ensure that the surface of the graphite crucible is bright and clean. Secondly, for the MOCVD method, specific metal organic compounds and gases are required to be used. First, an appropriate amount of Trimethylsilane (TMS) and ammonia (NH 3) are mixed together, heated to a certain temperature to sublimate it into metal vapor, and then introduced into a graphite crucible. Thirdly, controlling the temperature and atmosphere of the graphite crucible, and realizing the deposition of the coating by controlling the parameters such as the temperature, the gas mass ratio, the flow and the like in the silicon carbide deposition process. Fourthly, in the process of forming the coating, components and structures of the silicon carbide coating are monitored by means of detection of geometrical morphology (SEM), physical and chemical analysis and the like, so that the quality and uniformity of the coating are ensured. And fifthly, after the silicon carbide coating is deposited, the graphite crucible needs to be subjected to subsequent treatment, such as heat treatment or cooling, so as to ensure that the hardness and the density of the coating meet the requirements and improve the chemical and mechanical resistance of the coating.
The silicon carbide film is obtained by adopting an MOCVD method, and proper gas flow, nozzle temperature and medium atmosphere are required to be selected according to specific coating requirements so as to carry out reasonable parameter regulation and control.
In other embodiments, the refractory protective layer 12 is a silicon nitride coating, which may also be obtained according to the MOCVD process. The method is also in the prior art, mainly utilizes metal organic compounds, nitrogen and inert gas as reaction gases, and mainly comprises the following steps of the process of generating a silicon nitride coating through the gas phase reaction of depositing the metal organic compounds and the nitrogen on the surface of graphite: one is to select suitable metal organic compounds as precursors, such as SiH4, NH3, TMS, DMAH, etc., which can chemically react at elevated temperatures on the graphite surface. Secondly, placing the graphite crucible into an MOCVD reaction furnace, pre-treating, cleaning and drying to remove impurities and moisture on the surface. Thirdly, the deposition of the silicon nitride coating on the surface of the graphite is realized by injecting reaction gases such as metal organic compounds, nitrogen and the like into a reaction chamber of the reaction furnace. In the process, metal atoms generated by decomposition of the metal organic compound react with nitrogen to generate silicon nitride material which is deposited on the surface of graphite to form a uniform silicon nitride coating. And fourthly, after the reaction is finished, cooling treatment is carried out, and the graphite crucible is taken out of the reaction furnace, so that the silicon nitride coating with good oxidation and corrosion performances can be obtained.
In other embodiments, the high temperature resistant protective layer 12 is a graphite coating that may be obtained according to the PG process of pyrolytic graphite. The method is also in the prior art, and the graphite coating is coated on the surface of the graphite crucible, and the following steps are adopted: firstly, preparing a graphite source material: the graphite source material may be graphite powder or the like. Secondly, the graphite crucible is subjected to surface treatments, such as cleaning, polishing or etching, to increase the surface roughness and increase the surface area to which acceptable coatings adhere. Thirdly, powder metal tungsten or other metal catalysts are mixed in the graphite source material to obtain a mixture, so as to promote the pyrolysis reaction. And fourthly, adding an organic adhesive into the mixture and uniformly mixing to obtain a viscous graphite coating, and coating the graphite coating on the graphite crucible by using methods such as brushing. The coating should be uniformly distributed during coating and ensure adequate contact between the coating and the crucible surface. Fifth, pyrolyzing the graphite source material: the pyrolysis conditions are PG pyrolysis at normal pressure. In the pyrolysis process, graphite source materials are decomposed into carbon gas under the action of metal catalysts such as tungsten and the like, and then a graphite coating is deposited on the surface of a graphite crucible.
In other embodiments, the high temperature resistant protective layer 12 is a boron nitride coating that may be obtained according to the pyrolytic boron nitride PBN method. The method is also in the prior art, and comprises the following specific steps of: firstly, preparing a boron nitride precursor: boric acid, boron oxide and sol-gel method are used as raw materials, and BN precursor material is prepared by high-temperature sintering or high-temperature precipitation method. Secondly, surface treatment of the graphite crucible: the graphite crucible is subjected to chemical or physical treatments, such as ultrasonic cleaning, sand blasting, or electrochemical treatments, to increase the roughness of the crucible surface and increase the surface area to which acceptable coatings adhere. Thirdly, high temperature reaction: the graphite crucible is placed in a reaction chamber, and a precursor material is placed in a sub-chamber of the reaction chamber, so that the reaction chamber becomes a high-temperature atmosphere to perform a pyrolysis reaction. By choosing a suitable atmosphere, temperature and time, the precursor material can be decomposed into BN, which is then deposited as a coating on the graphite crucible surface. Fourthly, heat post treatment: after the coating is formed, the subsequent treatments such as temperature reduction, atmosphere switching and the like are carried out so as to eliminate possible crystallization defects and residues and ensure the quality and performance of the coating.
It should be noted that the PBN method requires the reaction of the graphite crucible in a high temperature atmosphere, which requires the selection of appropriate reaction parameters such as reaction temperature, reaction time, reaction atmosphere, etc., to control the BN deposition process.
Referring to fig. 3, the material of the side wall 22 of the outer crucible 2 is a carbon/carbon composite material, and the side wall 22 for preparing the carbon/carbon composite material is manufactured by a chemical vapor deposition method, which belongs to the prior art and can be manufactured by a carbon fiber mesh.
The method comprises the following specific steps: firstly, preparing a carbon fiber net-shaped object: high-strength and high-purity carbon fibers are selected for braiding to form a net. There are various methods of knitting, including hand knitting, machine knitting, and the like. The degree of engagement and tightness between the fibers should be noted during braiding to ensure stability and uniformity of the fiber network.
Secondly, gluing: the surface of the net is coated with glue to keep the bonding between the carbon fibers tight, so as to ensure the strength and stability of the whole crucible. The selection of the glue needs to take into account the stability and purity requirements during its preparation.
Thirdly, compression molding: glue is smeared on different positions of the carbon fiber net, and then compression molding is carried out. The shape and size of the crucible need to be carefully considered during pressing to ensure that it matches the required processing equipment. In general, the initial shape of the crucible can be formed by pressing using a mold at a high temperature.
Sintering: and sintering the crucible. The choice of sintering temperature and time depends on the crucible structure, size and material. Sintering can be realized by using equipment such as a high-temperature furnace, and the like, and carbon fibers and glue are fixed together through reaction mechanisms such as decomposition, recrystallization and the like at high temperature, so that a stable carbon/carbon composite material crucible is formed.
Fifth, the subsequent treatment: after sintering, the prepared carbon/carbon composite crucible is subjected to subsequent processing treatments including grinding and polishing to improve the surface finish and obtain the crucible with the required shape and performance.
The glue component used in the preparation of the carbon/carbon composite crucible is typically a charring resin. The charring Resin is a polymer organic material, and the main component is Polyimide Resin (Polyimide Resin). The carbonized resin has good carbonization performance, can be rapidly decomposed and carbonized under the high temperature condition to form solid carbonaceous firm particles, and can be combined with carbon fibers to form a stable structure of the crucible. Meanwhile, the carbonized resin has higher viscosity and adhesiveness, and can meet the requirement of glue for bonding carbon fiber meshes, so that an integral molding block is formed. In the processing of charring resins, auxiliary substances such as cross-linking agents, hardeners and additives are often required to adjust the viscosity, flowability and heat resistance of the glue. Different types of charring resins and auxiliary agents have different characteristics and application ranges, various selection and combination modes are provided, and proper products can be selected according to different process requirements.
Referring to fig. 4, the manufacturing method of the graphite crucible support 21 of the outer crucible 2 is similar to the manufacturing method of the crucible main body 11 of the inner crucible 1, and is not repeated.
Referring to fig. 5, in the production of the outer crucible 2, an outsourced viscous COPNA resin was selected, to which 20wt% of carbon fiber having a length of 1 to 2mm was added, and stirred uniformly to obtain a high-temperature adhesive. In the mounting, first, a high-temperature adhesive is applied to the lower annular portion 21-1 and the lower round table portion 21-2 of the crucible support 21. Secondly, the crucible side 22 is placed on the crucible support 21, and the upper circular ring part 22-1 of the crucible side 22 is located on the lower circular ring part 21-1 of the crucible support 21, and the outer crucible 2 with the crucible side 22 and the crucible support 21 matched together is obtained because the size and the dimension of the crucible side 22 are matched. And thirdly, placing the matched outer crucible 2 in a single crystal furnace for reheating, so that the COPNA resin is carbonized and sintered to form a high-temperature adhesive sinter 5, and further sintering and fixing the crucible side 22 and the crucible support 21 together to obtain the outer crucible 2 of the integrated structural member.
Referring to fig. 1, the installation procedure of the combination crucible of the present embodiment is as follows: firstly, the outsourced carborundum is selected as the raw material of the intermediate packing layer 3, and the size specification of the carborundum particles is 16 meshes. Secondly, the inner crucible 1 is placed in the outer crucible 2, the centers of the two crucibles are consistent, the inner crucible 1 is located by the bottom 1-3 of the crucible and is attached to the crucible support 21 of the outer crucible 2, so that corresponding gaps serving as filling gaps 4 are reserved between the outer walls of the side sections 1-1 and the transition sections 1-2 of the inner crucible 1 and the inner wall of the outer crucible 2, and the width d of the gaps between the side sections 1-1 of the inner crucible 1 and the outer crucible 2 is basically consistent, namely 7.5 mm. Thirdly, the mixed silicon carbide is put in the middle of the filling seam 4 of the inner crucible and the outer crucible. The radial length of the silicon carbide, i.e. the thickness of the intermediate filler layer 3, is the width d of the filler gap 4. Fourthly, the vibrating head of the ultrasonic vibration device is placed on the outer wall of the outer crucible 2, and the silicon carbide is tightly plugged in the middle of the filling gap 4 by the vibration of the ultrasonic vibration device to form the middle filling layer 3 (in other embodiments, the filling gap 4 can be plugged by other vibration modes such as mechanical vibration). The time length of the vibration is based on the fact that the thickness of the middle packing layer 3 at the upper section 1-1 of the inner crucible 1 is substantially the same (about 7.5 mm), and the packing is pressed by hand over the packing slit 4. An intermediate packing layer 3 is also present between the transition section 1-2 of the inner crucible 1 and the outer crucible 2 at this time, but their thickness is gradually reduced in order from top to bottom until it is zero. Thereby completing the installation of the combination crucible. The inner crucible 1 and the outer crucible 2 form an integral assembly, and are tightly fixed together in a rotating state during pulling. The inner crucible 1 is used for containing liquid silicon material when in use. The filling gap 4 is always reserved and cannot disappear due to deformation of the inner crucible 1 caused by temperature rise in use.
In other embodiments, the starting material for the intermediate packing layer 3 may be outsourced silicon nitride solid particulates, boron nitride solid particulates, alumina ceramic particulates, or zirconia ceramic particulates, or any two, three, or four of these five solid particulates.
When the combined crucible is used, the combined crucible is put into a single crystal furnace to replace the original combined crucible taking the quartz crucible as an inner crucible, and the rest steps for drawing the single crystal silicon rod are the same as corresponding operation steps.
Example 2
Referring to fig. 1 to 5, the rest of this embodiment is the same as embodiment 1 except that: the material of the crucible body 11 of the inner crucible 1 is silicon carbide, and the crucible body 11 is a silicon carbide crucible manufactured by a hot isostatic pressing method. The hot isostatic pressing is to sinter the blank at an isostatic pressure in at least three directions by maintaining a constant pressure at a high temperature. The silicon carbide crucible can withstand high temperatures up to 1800 ℃.
The preparation of silicon carbide crucible by hot isostatic pressing is a common method in the prior art, and comprises the following specific steps: firstly, preparing raw materials: the silicon carbide powder and the binder are uniformly mixed, and an organic resin is generally used as the binder. And secondly, placing the mixed silicon carbide powder and the binder into a mold, wherein the size of the mold is selected according to the size of the crucible main body 11. Thirdly, a prefabricated core rod is placed in the mold so as to form a hollow portion of the crucible during the molding process. Fourthly, the mould with the raw materials and the core rod is put into a hot pressing device, and the temperature is raised to a high temperature area, and the process is carried out at the high temperature of about 2000 ℃. Fifthly, applying 100-200MPa pressure at high temperature, so that the raw material and the core rod form a crucible shape under the action of high temperature and high pressure. Sixth, wait for crucible to cool and solidify, then take it out of the mould. Seventhly, cleaning, polishing and other subsequent treatments are carried out, so that the crucible main body 11 of silicon carbide is obtained.
Then, a high temperature resistant protective layer 12 was coated on the inner wall surface of the obtained crucible body 11 of silicon carbide, thereby obtaining an inner crucible 1. The silicon carbide crucible 11 exhibits excellent heat resistance in a high temperature environment and can withstand a high temperature of 2800 ℃ because of its high purity, high density, no oxidizing property, and being less susceptible to thermal expansion. The silicon carbide crucible has the characteristics of high strength, high hardness, high compression strength and the like, and can still maintain good mechanical strength under high temperature and severe working environments. The silicon carbide crucible has good corrosion resistance and corrosion resistance in most corrosive media except for oxidants, for example, the silicon carbide crucible is not damaged in molten metal, strong acid, strong alkali and other environments.
The method of forming the high temperature resistant protective layer 12 by covering the inner wall surface of the silicon carbide crucible 11 with the high temperature resistant protective layer 12 is similar to that of embodiment 1, and will not be described again. In other embodiments, a silicon nitride coating, a graphite coating, or a boron nitride coating may also be formed as its high temperature resistant protective layer 12. The method for forming these high temperature resistant protective layers 12 is similar to that of example 1, and will not be described again.
The material of the intermediate packing layer 3 is silicon carbide. In other embodiments, the raw material of the intermediate packing layer 3 may be silicon nitride solid particles or boron nitride solid particles, or a mixture of solid particles of three materials of silicon carbide, silicon nitride and boron nitride, or any two of the solid particles of the three materials.
Example 3
Referring to fig. 1 to 5, the rest of this embodiment is the same as embodiment 1 except that: the material of the crucible body 11 of the inner crucible 1 is silicon nitride, and the crucible body 11 is a silicon nitride crucible manufactured by a hot isostatic pressing method. The silicon nitride crucible can withstand high temperatures up to 1650 ℃.
The isostatic compaction method for preparing the silicon nitride crucible is a common method in the prior art, and comprises the following specific steps: firstly, preparing raw materials: and uniformly mixing the silicon nitride powder and the binder. As the binder, an organic resin or an inorganic colloid is generally used. And secondly, placing the mixed silicon nitride powder and the binder into a mold, wherein the size of the mold is selected according to the size of the crucible main body 11. Thirdly, a prefabricated core rod is placed in the mold so as to form a hollow portion of the crucible during the molding process. Fourth, the mold containing the raw material and the mandrel is placed in a hot press apparatus and the temperature is raised to a high temperature region, typically at a high temperature of about 1800 ℃. Fifthly, high pressure is applied at high temperature, so that the raw material and the core rod form a crucible shape under the action of high temperature and high pressure. The pressure is typically above 100 MPa. And sixthly, static pressure is carried out under the high pressure and high temperature state, so that the crucible material is densified, and the holding time is 1-2 hours. Seventhly, slowly cooling to room temperature, and then taking the crucible out of the mold. Eighth, the crucible body 11 of silicon nitride is obtained through subsequent treatments such as cleaning and polishing.
It should be noted that silicon nitride materials are easily oxidized at high temperatures, and to avoid oxidation, preparation is typically performed under inert atmosphere or vacuum conditions.
The method of forming the high temperature resistant protective layer 12 by covering the inner wall surface of the silicon carbide crucible 11 with the high temperature resistant protective layer 12 is similar to that of embodiment 1, and will not be described again.
In other embodiments, a silicon nitride coating, a graphite coating, or a boron nitride coating may also be formed as its high temperature resistant protective layer 12. The method for forming these high temperature resistant protective layers 12 is similar to that of example 1, and will not be described again.
The material of the intermediate packing layer 3 is silicon carbide. In other embodiments, the starting material for the intermediate packing layer 3 may be outsourced silicon nitride solid particulates, boron nitride solid particulates, alumina ceramic particulates, or zirconia ceramic particulates, or any two, three, or four of these five solid particulates.
Example 4
Referring to fig. 1 to 5, the rest of this embodiment is the same as embodiment 1 except that: the material of the crucible main body 11 of the inner crucible 1 is boron nitride, and the crucible main body 11 is a boron nitride crucible manufactured by a hot press molding method. The boron nitride crucible can withstand high temperatures up to 1800 ℃. The isostatic compaction method for preparing the boron nitride crucible is a common method in the prior art, and comprises the following specific steps: firstly, preparing raw materials of a boron nitride crucible: the raw materials of the boron nitride crucible mainly comprise ammonia borane, boron powder and boron nitride powder, and the ammonia borane, the boron powder and the boron nitride powder are required to be mixed according to a certain proportion. Secondly, ball milling and mixing: the raw materials with different proportions are added into a ball milling tank, ball milling and mixing are carried out in the ball milling tank, and in the process, the raw materials are gradually refined and uniformly mixed. And thirdly, drying: and drying the mixture after ball milling to remove water and organic matters. And fourthly, prepressing. And (3) placing the dried boron nitride crucible raw material into a mould, and pre-pressing and forming to form a prefabricated blank body, wherein the shape and the size of the prefabricated blank body are similar to those of a finished crucible. The density of the preform is typically in the range of 50% -70%. Fifthly, performing hot press molding. And placing the prefabricated blank body into a hot press for hot press molding. The hot pressing temperature is usually higher than 2000 ℃, and the pressure and the pressing time are adjusted and controlled according to the size and the thickness of the generated boron nitride crucible so as to realize the compactness and the ideal geometric shape of the boron nitride crucible. Finally, the boron nitride crucible product used at high temperature can be obtained. And sixthly, performing post-treatment. After the boron nitride crucible is manufactured, the steps of post-treatment, cleaning, processing and the like are needed to meet different use requirements.
When the boron nitride crucible is manufactured, a hot press molding method is adopted, because the powdery raw material is firstly manufactured into a blocky green body, and then the green body is hot press molded under the conditions of high temperature and high pressure such as tungsten stone, etc. so as to achieve the required density and shape. During the heating of the green body, the powder particles continue to grow due to oxidation or reduction, forming a crucible sintered body. After hot pressing treatment, a compact, firm, wear-resistant and stable boron nitride crucible product can be obtained. Therefore, the hot press forming and the isostatic press forming are basically the same technical method, and in the manufacturing process of the boron nitride crucible, the hot press forming technology is mainly adopted so as to achieve higher compactness and sintering quality. Isostatic pressing is suitable for large-scale and high-density ceramic preparation, and hot pressing can prepare ceramic materials with more excellent performance. In the preparation of boron nitride crucibles, a hot press forming process is often used to obtain dense and well performing boron nitride crucibles. In the hot press molding process, a great amount of dislocation is introduced into the raw materials in a mode of applying unequal static force, so that the material is sintered after plastic deformation, more uniform crystal grains and stronger binding force are obtained, the material is more compact, the performances of oxidation resistance, heat resistance and the like are obviously improved, but the mechanical property is generally poorer than that of isostatic press molding.
The method of forming the high temperature resistant protective layer 12 by covering the inner wall surface of the boron nitride crucible 11 with the high temperature resistant protective layer 12, which is a silicon carbide film, is similar to that of example 1, and will not be described again.
In other embodiments, a silicon nitride coating, a graphite coating, or a boron nitride coating may also be formed as its high temperature resistant protective layer 12. The method for forming these high temperature resistant protective layers 12 is similar to that of example 1, and will not be described again.
The material of the intermediate packing layer 3 is silicon carbide. In other embodiments, the starting material for the intermediate packing layer 3 may be outsourced silicon nitride solid particulates, boron nitride solid particulates, alumina ceramic particulates, or zirconia ceramic particulates, or any two, three, or four of these five solid particulates.
In the above 4 embodiments of the present utility model, the graphite crucible, the silicon carbide crucible, the silicon nitride crucible, and the boron nitride crucible can be used to melt liquid silicon or hold liquid silicon material at high temperature, and the four crucibles are different in terms of the degree of firmness. Graphite is more brittle than silicon carbide, silicon nitride and boron nitride, which have good corrosion resistance and can be used under extreme conditions. And even at different costs. Because of the different crucible materials and manufacturing processes, the cost of each crucible is different, the cost of a common graphite crucible is relatively low, and the cost of a boron nitride crucible is relatively high.
In the research and development process of the utility model, quartz sand is tried to be used as the material of the intermediate packing layer 3, but the intermediate packing layer 3 made of the material is softened in the crystal pulling process, so that the inner crucible and the outer crucible are unstable in rotation, and the efficient crystal pulling is not facilitated. This means that the use of other solid particles which soften at high temperatures in the intermediate packing layer 3 will also be detrimental to the effective crystal pulling process.
Claims (6)
1. A combined crucible for pulling a single crystal rod by a single crystal furnace is provided with a high-temperature resistant inner crucible (1) and a high-temperature resistant outer crucible (2); the outer crucible (2) is an integral structural member; the inner crucible (1) is arranged in the outer crucible (2); the method is characterized in that: the intermediate filler layer (3) is high-temperature resistant and good in heat conduction performance; the inner crucible (1) comprises a high-temperature resistant protective layer (12) and a high-temperature resistant crucible main body (11) of a homogeneous integrated piece; the high-temperature resistant protective layer (12) is a coating and is covered and fixed on the inner wall of the crucible main body (11), so as to play a role in sealing the inner wall of the crucible main body (11); a gap serving as a filling gap (4) is reserved between the inner crucible (1) and the outer crucible (2); the intermediate packing layer (3) is an aggregate of solid particles, is arranged in the packing gap (4) and is tightly plugged between the inner crucible (1) and the outer crucible (2), so that the inner crucible (1) and the outer crucible (2) are tightly matched together through the intermediate packing layer (3) to form an integral assembly.
2. The combination crucible for pulling a single crystal ingot in a single crystal furnace of claim 1, wherein: the inner crucible (1) sequentially comprises a pot upper section (1-1), a transition section (1-2) and a pot bottom (1-3) from top to bottom, and the thicknesses of the parts are basically the same; the inner crucible (1) is located by the bottom (1-3) of the pot and is attached to the outer crucible (2), and corresponding gaps remained between the outer walls of the upper section (1-1) and the transition section (1-2) of the inner crucible (1) and the inner wall of the outer crucible (2) are used as filling gaps (4); the width of the filling gap (4) refers to the interval between the outer wall of the pot side section (1-1) of the inner crucible (1) and the inner wall of the outer crucible (2), and the interval is 2.1 mm to 15 mm; the size specification of the solid particles of the intermediate filler layer (3) is 10 to 20 mesh.
3. A combination crucible for use in pulling a single crystal ingot in a single crystal furnace as set forth in claim 2, wherein: the size specification of the solid particles of the intermediate filler layer (3) is 16+/-1 meshes, and the width of the filler gaps (4) is 3-10 mm.
4. The combination crucible for pulling a single crystal ingot in a single crystal furnace of claim 1, wherein: the thickness of the crucible main body (11) of the inner crucible (1) is 8-15 mm, and the thickness of the high-temperature resistant protective layer (12) of the inner crucible (1) is 1-50 microns.
5. A combination crucible for use in pulling a single crystal ingot in a single crystal furnace as set forth in any one of claims 1 to 4, wherein: the outer crucible (2) comprises a crucible support (21) and a crucible side (22); the lower part of the crucible side (22) is matched with the upper part of the crucible support (21), and the crucible side and the crucible support are hermetically and fixedly connected to form an integrated structural member.
6. The combination crucible for pulling a single crystal ingot in a single crystal furnace of claim 5, wherein: also has a high temperature binder sinter (5); the high-temperature adhesive sinter (5) is sintered between the crucible side (22) of the outer crucible (2) and the crucible support (21), so that the crucible side (22) and the crucible support (21) are fixedly connected together, and the outer crucible (2) is an integral structural member.
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