Repair method of quartz crucible

Abstract

The invention provides a quartz crucible repairing method. The quartz crucible repairing method comprises the following steps that S1, appearance defects on the inner surface of a quartz crucible to be repaired are removed through mechanical grinding; s2) carrying out high-temperature fusion welding on the to-be-repaired part of the quartz crucible with appearance defects removed and a quartz rod, and then carrying out annealing treatment; s3) polishing the welding part of the quartz crucible subjected to annealing treatment; s4) carrying out accurate grinding treatment on the ground quartz crucible by utilizing grinding powder; s5) cleaning the quartz crucible subjected to the fine grinding treatment; and (S6) the cleaned crucible is subjected to electric arc melting. Compared with the prior art, the repairing method provided by the invention combines high-temperature fusion welding with a quartz crucible electric arc melting technology, can effectively improve the production qualification rate of the quartz crucible, reduces the cost, and is simple in process and easy to industrially popularize.

Description

Technical Field

[0001] The invention belongs to the technical field of quartz crucibles, and in particular relates to a repairing method for a quartz crucible. Background Art

[0002] Quartz crucibles are used as containers for molten silicon when large-diameter single crystal silicon is pulled by the CZ method. They are essential basic materials for the photovoltaic industry to prepare solar cells and develop large-scale integrated circuits.

[0003] Currently, quartz crucibles are primarily produced through arc melting, a process that can be summarized as follows: quartz sand → mold filling and forming → arc melting → demolding → cooling (air cooling) → cleaning → packaging. During the production process, quartz crucibles are susceptible to external factors such as raw materials, the environment, equipment, and human operation, leading to defects such as bubbles, black spots, and other impurities adhering to the crucible's inner wall. During the production of single crystal silicon rods, the inner wall of the quartz crucible comes into direct contact with the silicon solution. During the growth of the single crystal silicon rod, impurities or bubbles in the transparent layer of the quartz crucible are easily eroded by the molten silicon and dissolved from the transparent layer into the silicon solution, causing breakage during the crystal pulling process and affecting the quality of the silicon rod. Therefore, quartz crucibles with these defects are unusable and must be scrapped.

[0004] Furthermore, as single-crystal silicon wafers grow in size, the size of quartz crucibles continues to increase. Consequently, the raw material, quartz sand, is in short supply and its price is skyrocketing. Inner layer sand, in particular, relies heavily on imports, leading to increasing manufacturing costs for quartz crucibles. To reduce production costs and minimize resource waste, a method for repairing large-scale quartz crucibles with defects in the inner wall and transparent layer is urgently needed.

[0005] Chinese patent publication number CN116765992 discloses a quartz crucible repair device and method. The inner wall of the quartz crucible is precisely ground and polished by grinding and polishing tools to remove defects on the inner surface of the crucible. However, the roughness of the repaired area is poor, resulting in increased crystal pulling costs, and the process cannot eliminate defects such as black spots and bubbles deep inside the inner wall of the crucible.

[0006] Chinese patent publication number CN102583976A discloses an arc method for repairing defects in quartz crucibles. The method involves melting a quartz glass rod with oxyhydrogen gas for repair, polishing the surface with an oxyhydrogen flame, and finally annealing to make it a qualified product. However, this method involves many steps and is only suitable for small crucibles of 18 to 28 inches. For large crucibles of 32 to 42 inches, due to their large size and heavy weight, large-scale defects such as fingerprints and scratches are easily generated during transportation. In addition, the oxyhydrogen flame polishing covers a small area and takes a long time. Due to limitations in manpower and equipment, the repair is difficult and inefficient. Summary of the Invention

[0007] In view of this, the technical problem to be solved by the present invention is to provide a quartz crucible repair method, which can effectively improve the product failure rate and reduce production costs.

[0008] The present invention provides a method for repairing a quartz crucible, comprising the following steps:

[0009] S1) removing appearance defects on the inner surface of the quartz crucible to be repaired by mechanical grinding;

[0010] S2) performing high-temperature melting welding on the part to be repaired of the quartz crucible from which the appearance defects have been removed and the quartz rod, and then performing annealing treatment;

[0011] S3) polishing the welding position of the quartz crucible after the annealing treatment;

[0012] S4) fine grinding the polished quartz crucible using abrasive powder;

[0013] S5) cleaning the quartz crucible after fine grinding;

[0014] S6) arc melting the cleaned crucible: first preheating the crucible at a current of 1000-2000 A, then holding the crucible at a current of 2500-3500 A, and finally cooling the crucible at a current of 2000-2500 A to obtain a repaired quartz crucible.

[0015] Preferably, in step S2), high-temperature melting welding is performed using an oxyhydrogen flame; during welding, the hydrogen pressure of the oxyhydrogen flame is 0.3-0.6 MPa, and the oxygen pressure is 0.6-1.2 MPa; the flame temperature of the oxyhydrogen flame is not less than 1800°C.

[0016] Preferably, the temperature of the annealing treatment in step S2) is 900° C. to 1300° C.; and the time of the annealing treatment is 30 to 120 minutes.

[0017] Preferably, in step S3), the grinding is performed using a grinding sheet; the mesh number of the grinding sheet is 50 to 1000.

[0018] Preferably, the particle size of the powder in step S4) is 200-800 mesh.

[0019] Preferably, in step S5), the finely ground quartz crucible is cleaned with an acidic solution; the acidic solution is selected from one or more of hydrofluoric acid solution, sulfuric acid solution, hydrochloric acid solution, nitric acid solution and ammonium fluoride solution.

[0020] Preferably, the preheating treatment time in step S6) is 3 to 7 minutes; the heat preservation treatment time is 1 to 10 minutes.

[0021] Preferably, in step S6), the cooling time under the current condition of 2000-2500 A is 10-100 s.

[0022] Preferably, the cooling rate of the cooling treatment in step S6) does not exceed 10°C / s.

[0023] Preferably, the average roughness of the inner surface of the repaired quartz crucible is 0.04-0.06 μm.

[0024] The invention provides a quartz crucible repair method, comprising the following steps: S1) removing appearance defects on the inner surface of the quartz crucible to be repaired by mechanical grinding; S2) performing high-temperature melting welding on the part of the quartz crucible to be repaired, from which the appearance defects have been removed, and a quartz rod, and then performing annealing treatment; S3) grinding the welded part of the quartz crucible after the annealing treatment; S4) fine-grinding the ground quartz crucible with grinding powder; S5) cleaning the fine-grinded quartz crucible; S6) arc melting the cleaned crucible: first, preheating treatment is performed under a current condition of 1000 to 2000 A, then heat preservation treatment is performed under a current condition of 2500 to 3500 A, and finally cooling is performed under a current condition of 2000 to 2500 A, to obtain a repaired quartz crucible. Compared with the existing technology, the repair method provided by the present invention combines high-temperature melting welding with quartz crucible arc melting technology, which can effectively improve the production qualification rate of quartz crucibles, reduce costs, simplify the process, and is easy to promote industrialization. DETAILED DESCRIPTION

[0025] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] The invention provides a quartz crucible repair method, comprising the following steps: S1) removing appearance defects on the inner surface of the quartz crucible to be repaired by mechanical grinding; S2) performing high-temperature melting welding on the part of the quartz crucible to be repaired, from which the appearance defects have been removed, and a quartz rod, and then performing annealing treatment; S3) grinding the welded part of the quartz crucible after the annealing treatment; S4) fine-grinding the ground quartz crucible with grinding powder; S5) cleaning the fine-grinded quartz crucible; S6) arc melting the cleaned crucible: first, preheating treatment is performed under a current condition of 1000 to 2000 A, then heat preservation treatment is performed under a current condition of 2500 to 3500 A, and finally cooling is performed under a current condition of 2000 to 2500 A, to obtain a repaired quartz crucible.

[0027] The present invention has no particular limitation on the sources of all raw materials, and any commercially available raw materials may be used.

[0028] In the present invention, the appearance defects of the inner surface of the quartz crucible to be repaired are first removed by mechanical grinding; the appearance defects include but are not limited to black spots and / or bubbles; the tools used for mechanical grinding include but are not limited to diamond, silicon carbide, corundum and other powder materials with a hardness greater than quartz and / or tools made thereof.

[0029] The part to be repaired of the quartz crucible with the appearance defects removed is subjected to high-temperature melting welding with a quartz rod; the part to be repaired is repaired by high-temperature melting welding; the high-temperature melting welding is preferably performed using an oxyhydrogen flame; the hydrogen pressure of the oxyhydrogen flame during welding is preferably 0.3-0.6 MPa, more preferably 0.4-0.6 MPa; the oxygen pressure of the oxyhydrogen flame during welding is preferably 0.6-1.2 MPa, more preferably 0.7-1.1 MPa, and even more preferably 0.8-1 MPa; the flame temperature of the oxyhydrogen flame is preferably not less than 1800°C; the tools provided by the oxyhydrogen flame include but are not limited to oxyhydrogen flame welding guns, oxyhydrogen flame focusing guns, etc., and further include but are not limited to 6# oxyhydrogen flame welding guns, oxyhydrogen flame focusing guns, etc.

[0030] The quartz crucible after high-temperature melting and welding is annealed to eliminate stress; since crucibles of different sizes have different volumes, the temperature and time of the annealing treatment can be selected according to the size of the crucible, and the efficiency can be improved by appropriately increasing or decreasing the annealing time; the temperature of the annealing treatment is preferably 900°C to 1300°C; optionally, the temperature of the annealing treatment is 900°C, 1000°C, 1100°C, 1150°C, 1200°C, 1300°C or a range between any two of the above values; the time of the annealing treatment is preferably 30 to 120 minutes; optionally, the time of the annealing treatment is 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 120 minutes or a range between any two of the above values.

[0031] The welding part of the quartz crucible after annealing is polished; in the present invention, it is preferably polished with a polishing sheet; the polishing sheet is preferably a water-polished sheet; the mesh number of the polishing sheet is preferably 50 to 1000 mesh; optionally, the mesh number of the polishing sheet is 50 mesh, 100 mesh, 150 mesh, 200 mesh, 300 mesh, 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, 900 mesh, 1000 mesh or a range between any two of the above values; in the present invention, it is preferably polished until the polished area and other areas have a smooth transition, the touch is smooth and without bumps, and there are no ripples when observed under an incandescent lamp.

[0032] In a specific embodiment provided by the present invention, it is preferred to use grinding sheets of different mesh sizes to grind the welding parts of the quartz crucible after annealing in sequence; the grinding preferably includes coarse grinding, fine grinding and fine grinding; the coarse grinding preferably uses a grinding sheet of 50-200 mesh, more preferably a grinding sheet of 100-200 mesh; the coarse grinding time is preferably 1-5 min, more preferably 1-3 min, and more preferably 2 min; the fine grinding preferably uses a grinding sheet of 400-800 mesh, more preferably a grinding sheet of 400-600 mesh, and more preferably a grinding sheet of 500 mesh; the fine grinding time is preferably 1-10 min, more preferably 3-8 min, more preferably 4-6 min, and most preferably 5 min; the fine grinding preferably uses a grinding sheet of 900-1000 mesh; the fine grinding time is preferably 1-10 min, more preferably 3-8 min, more preferably 4-6 min, and most preferably 5 min.

[0033] The polished quartz crucible is finely ground using a grinding powder; the grinding powder includes but is not limited to silicon carbide grinding powder, diamond grinding powder, corundum grinding powder, and other grinding powders with a hardness greater than quartz; the particle size of the grinding powder is preferably 200-800 mesh; optionally, the particle size of the grinding powder is 200 mesh, 300 mesh, 400 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh, or a range between any two of the above values; in the present invention, the fine grinding process is preferably performed until there are no knife marks observed with the naked eye and no graininess is felt when touched. In a specific embodiment provided by the present invention, the fine grinding process is preferably performed for 5-20 minutes, more preferably 8-15 minutes, and even more preferably 10 minutes.

[0034] The finely ground quartz crucible is cleaned to remove surface impurities. In the present invention, an acidic solution is preferably used to clean the finely ground quartz crucible. The acidic solution is preferably one or more of hydrofluoric acid, sulfuric acid, hydrochloric acid, nitric acid, and ammonium fluoride. In a specific embodiment of the present invention, a mixed acid solution is preferably used for cleaning. The mixed acid solution includes hydrofluoric acid and sulfuric acid. The concentration of hydrofluoric acid in the mixed acid solution is preferably 10%, and the concentration of sulfuric acid in the mixed acid solution is preferably 5%.

[0035] The cleaned crucible is arc-melted: first, it is preheated at a current of 1000-2000A, then kept warm at a current of 2500-3500A, and finally cooled at a current of 2000-2500A to obtain a repaired quartz crucible.

[0036] Optionally, the current condition of the preheating treatment is 1000A, 1100A, 1200A, 1300A, 1400A, 1500A, 1600A, 1700A, 1800A, 1900A, 2000A or a range between any two of the above values.

[0037] In a specific embodiment provided by the present invention, the preheating treatment time is preferably 3 to 7 minutes, more preferably 4 to 7 minutes, and even more preferably 5 to 6 minutes.

[0038] Optionally, the current condition of the insulation treatment is 2500A, 2600A, 2700A, 2800A, 2900A, 3000A, 3100A, 3200A, 3300A, 3400A, 3500A or a range between any two of the above values.

[0039] In a specific embodiment provided by the present invention, the time of the heat preservation treatment is preferably 1 to 10 minutes, more preferably 3 to 8 minutes, and even more preferably 3 to 5 minutes.

[0040] Optionally, the current condition of the cooling treatment is 2000A, 2100A, 2100A, 2300A, 2400A, 2500A or a range between any two of the above values.

[0041] In a specific embodiment provided by the present invention, the current condition of the cooling treatment is preferably such that the cooling rate does not exceed 10° C. / s.

[0042] In a specific embodiment provided by the present invention, the time for the cooling treatment is preferably 10 to 100 s, more preferably 20 to 90 s, further preferably 30 to 80 s, and most preferably 40 to 60 s.

[0043] After the cooling treatment, preferably cooling to room temperature, the crucible is cleaned to obtain a repaired quartz crucible. The cleaning is preferably performed using an acidic solution; the acidic solution is preferably one or more of hydrofluoric acid solution, sulfuric acid solution, hydrochloric acid solution, nitric acid solution, and ammonium fluoride solution. In a specific embodiment provided by the present invention, the cleaning is preferably performed using a mixed acid solution; the mixed acid solution includes hydrofluoric acid and sulfuric acid; the concentration of hydrofluoric acid in the mixed acid solution is preferably 10%; the concentration of sulfuric acid in the mixed acid solution is preferably 5%.

[0044] In a specific embodiment provided by the present invention, the average roughness of the inner surface of the repaired quartz crucible is preferably 0.04 to 0.06 μm, more preferably 0.043 to 0.053 μm.

[0045] The repair method provided by the present invention combines high-temperature melting welding with quartz crucible arc melting technology, which can effectively improve the production qualification rate of quartz crucibles, reduce costs, simplify the process, and is easy to promote industrialization.

[0046] In order to further illustrate the present invention, a method for repairing a quartz crucible provided by the present invention is described in detail below with reference to embodiments.

[0047] The reagents used in the following examples are all commercially available.

[0048] Example 1

[0049] 1.1 The black spots on the inner surface of the quartz crucible (37 inches) were mechanically ground away.

[0050] 1.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1150℃ and the annealing time is 1h.

[0051] 1.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0052] 1.4 After grinding with the grinding disc, use 500 mesh silicon carbide grinding powder to fine grind for 10 minutes until there are no knife marks when observed with the naked eye and there is no granularity when touching the surface. The grinding medium used is pure water.

[0053] 1.5 The crucible after grinding is cleaned to remove surface impurities. The cleaning solution used is a mixed solution of hydrofluoric acid and sulfuric acid. The concentration of hydrofluoric acid in the mixed solution is 10% and the concentration of sulfuric acid is 5%.

[0054] 1.6 The crucible after pickling was remelted by arc melting, and its roughness was tested after cooling to room temperature. The process conditions were preheating for 5 minutes at a current of 1500A, then keeping warm for 5 minutes at a current of 2800A, and finally cooling for 40 seconds at a current of 2200A. The surface dust and impurities were cleaned and removed with a mixed solution of hydrofluoric acid and sulfuric acid (the concentration of hydrofluoric acid in the mixed solution was 10% and the concentration of sulfuric acid was 5%) to obtain the repaired crucible.

[0055] Example 2

[0056] 2.1 to 2.5 are the same as 1.1 to 1.5 in Example 1.

[0057] 2.6 The crucible after pickling was remelted by arc melting, and its roughness was tested after cooling to room temperature. The process conditions were preheating for 6 minutes at a current of 1200A, then keeping warm for 3 minutes at a current of 3200A, and finally cooling for 40 seconds at a current of 2200A. The surface dust and impurities were cleaned and removed using a mixed solution of hydrofluoric acid and sulfuric acid (the concentration of hydrofluoric acid in the mixed solution was 10% and the concentration of sulfuric acid was 5%) to obtain the repaired crucible.

[0058] Example 3

[0059] 3.1 to 3.5 are the same as 1.1 to 1.5 in Example 1.

[0060] 3.6 The crucible after pickling was remelted by arc melting, and its roughness was tested after cooling to room temperature. The process conditions were preheating for 5 minutes at a current of 1800A, then keeping warm for 5 minutes at a current of 3000A, and finally cooling for 60 seconds at a current of 2500A. The surface dust and impurities were cleaned and removed using a mixed solution of hydrofluoric acid and sulfuric acid (the concentration of hydrofluoric acid in the mixed solution was 10% and the concentration of sulfuric acid was 5%) to obtain the repaired crucible.

[0061] Comparative Example 1

[0062] A 32-inch photovoltaic quartz crucible was prepared using the Chinese patent publication number CN116081928A, and its inner surface roughness was directly tested.

[0063] Comparative Example 2

[0064] 2.1 The black spots on the inner surface of the quartz crucible (37 inches) were mechanically ground and removed.

[0065] 2.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1150℃ and the annealing time is 1h.

[0066] 2.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0067] 2.4 Grinding The crucible after grinding is further fine-grinded using a 1000-2000 mesh water-grinding sheet to obtain a smooth surface. Specifically, use a 1500 mesh water-grinding sheet for fine grinding for 5 minutes and a 2000 mesh water-grinding sheet for fine grinding for 5 minutes.

[0068] 2.5 Use cerium oxide polishing paste (particle size W 0.05μm) and a wool polishing pad to mechanically polish the finely ground surface until it is transparent and smooth to the touch, obtain a smooth surface and test its roughness.

[0069] Comparative Example 3

[0070] 3.1 The black spots on the inner surface of the quartz crucible (37 inches) were mechanically ground and removed.

[0071] 3.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1150℃ and the annealing time is 1h.

[0072] 3.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0073] 3.4 Use a 1000-2000 mesh water-polishing sheet to continue fine-grinding the crucible after polishing to obtain a smooth surface. Specifically, use a 1500 mesh water-polishing sheet for fine grinding for 5 minutes and a 2000 mesh water-polishing sheet for fine grinding for 5 minutes.

[0074] 3.4 Use a 3000-mesh water-abrasive disc to mechanically polish the finely ground surface until it is transparent and smooth to the touch. Obtain a smooth surface and test its roughness.

[0075] Comparative Example 4

[0076] 4.1 Remove the bubble defects on the inner surface of the quartz crucible (32 inches) by mechanical grinding.

[0077] 4.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1150℃ and the annealing time is 40min.

[0078] 4.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0079] 4.4 Wash the polished crucible to remove surface impurities. The cleaning solution used is a mixed solution of hydrofluoric acid and sulfuric acid. The concentration of hydrofluoric acid in the mixed solution is 10% and the concentration of sulfuric acid is 5%.

[0080] 4.5 Use a 1000 mesh water grinding wheel to finely grind the cleaned crucible for 8 minutes to refine the grinding marks and obtain a smooth surface.

[0081] 4.6 Use hydrogen-oxygen flame to fire-polish the surface of the fine-ground product until it is transparent, forming a smooth glaze or mirror surface. After cooling to room temperature, test its roughness. The tool used is a 6# hydrogen-oxygen flame welding gun, the hydrogen pressure is 0.4MPa, and the oxygen pressure is 0.8MPa.

[0082] Comparative Example 5

[0083] 5.1 The inner surface of the quartz crucible (37 inches) with black spots and bubble defects was mechanically ground away.

[0084] 5.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1150℃ and the annealing time is 40min.

[0085] 5.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0086] 5.4 After grinding with the grinding disc, use 500 mesh silicon carbide grinding powder to fine grind for 10 minutes until there are no knife marks when observed with the naked eye and there is no granularity when touched. The grinding medium used is pure water.

[0087] 5.5 The crucible after grinding is cleaned to remove surface impurities. The cleaning solution used is a mixed solution of hydrofluoric acid and sulfuric acid. The concentration of hydrofluoric acid in the mixed solution is 10% and the concentration of sulfuric acid is 5%.

[0088] 5.6 Use oxyhydrogen flame to fire polish the surface of the cleaned product until it is transparent, forming a smooth glaze or mirror. After cooling to room temperature, test its roughness. The tool used is a 6# oxyhydrogen flame welding gun, the hydrogen pressure is 0.4MPa, and the oxygen pressure is 0.8MPa.

[0089] Comparative Example 6

[0090] 6.1 The black spots on the inner surface of the quartz crucible (37 inches) were mechanically ground away.

[0091] 6.2 Use a high-temperature hydrogen-oxygen flame to melt and weld the quartz rod and the quartz crucible to be repaired (during welding, the hydrogen pressure is 0.4MPa, the oxygen pressure is 0.8MPa; the hydrogen combustion color is bright white, and the flame temperature is not less than 1800℃). After the repair is completed, transfer it to a high-temperature furnace for annealing to eliminate stress. The annealing temperature is 1100℃ and the annealing time is 40min.

[0092] 6.3 After annealing, the welding parts of the crucible are polished and smooth by mechanical grinding (requirements: smooth transition between the polished area and other areas, smooth touch without bumps, and no ripples when observed under incandescent light). The mesh number of the polishing sheet used is 100-1000 mesh, and the grinding medium used is pure water. Specifically, first use 100 mesh for coarse grinding for 2 minutes, then use 500 mesh for fine grinding for 5 minutes, and then use 1000 mesh for fine grinding for 5 minutes.

[0093] 6.4 After grinding with the grinding disc, use 500 mesh silicon carbide grinding powder to fine grind for 10 minutes until there are no knife marks when observed with the naked eye and there is no graininess when touching the surface. The grinding medium used is pure water.

[0094] 6.5 The crucible after grinding is cleaned to remove surface impurities. The cleaning solution used is a mixed solution of hydrofluoric acid and sulfuric acid. The concentration of hydrofluoric acid in the mixed solution is 10% and the concentration of sulfuric acid is 5%.

[0095] 6.6 Use an oxyhydrogen flame to fire-polish the surface of the cleaned product until it is transparent, forming a smooth glaze or mirror surface. After cooling to room temperature, test its roughness. The tool used is an oxyhydrogen flame gun with a hydrogen pressure of 0.6 MPa and an oxygen pressure of 1.0 MPa.

[0096] The roughness of the inner surfaces of the repaired quartz crucibles in Examples 1 to 3, the quartz crucible obtained in Comparative Example 1, and the repaired quartz crucibles in Comparative Examples 2 to 6 were tested using a handheld contact roughness meter. The results are shown in Table 1.

[0097] Table 1 Roughness test average value of inner surface of quartz crucible / μm

[0098]

[0099]

[0100] As can be seen from Table 1, the average surface roughness of the quartz crucibles repaired by the repair methods of Examples 1 to 3 is similar to the average surface roughness of qualified products produced normally.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for repairing a quartz crucible, characterized in that: The following steps are involved: S1) removing appearance defects on the inner surface of the quartz crucible to be repaired by mechanical grinding; S2) performing high-temperature melting welding on the part to be repaired of the quartz crucible from which the appearance defects have been removed and the quartz rod, and then performing annealing treatment; S3) polishing the welding position of the quartz crucible after the annealing treatment; S4) fine grinding the polished quartz crucible using abrasive powder; S5) cleaning the quartz crucible after fine grinding; S6) arc melting the cleaned crucible: first preheating the crucible at a current of 1000-2000 A, then holding the crucible at a current of 2500-3500 A, and finally cooling the crucible at a current of 2000-2500 A to obtain a repaired quartz crucible.

2. The repair method according to claim 1, characterized in that: In step S2), high-temperature melting welding is performed using an oxyhydrogen flame; during welding, the hydrogen pressure of the oxyhydrogen flame is 0.3-0.6 MPa, and the oxygen pressure is 0.6-1.2 MPa; the flame temperature of the oxyhydrogen flame is not less than 1800°C.

3. The repair method according to claim 1, characterized in that: The temperature of the annealing treatment in step S2) is 900° C. to 1300° C.; and the time of the annealing treatment is 30 to 120 minutes.

4. The repair method according to claim 1, characterized in that: In the step S3), the grinding is performed using a grinding sheet; the mesh number of the grinding sheet is 50 to 1000.

5. The repair method according to claim 1, characterized in that: The particle size of the ground powder in step S4) is 200-800 mesh.

6. The repair method according to claim 1, characterized in that: In the step S5), the quartz crucible after fine grinding is cleaned with an acidic solution; The acidic solution is selected from one or more of hydrofluoric acid solution, sulfuric acid solution, hydrochloric acid solution, nitric acid solution and ammonium fluoride solution.

7. The repair method according to claim 1, characterized in that: The preheating treatment time in step S6) is 3 to 7 minutes; the heat preservation treatment time is 1 to 10 minutes.

8. The repair method according to claim 1, characterized in that: In the step S6), the time for the temperature reduction treatment under the current condition of 2000-2500 A is 10-100 seconds.

9. The repair method according to claim 1, characterized in that: The cooling rate of the cooling treatment in step S6) does not exceed 10°C / s.

10. The repair method according to claim 1, characterized in that: The average roughness of the inner surface of the repaired quartz crucible is 0.04-0.06 μm.

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