A crucible for preparing aluminum-vanadium alloy by aluminothermic reaction and a method for preparing the same

Abstract

A kind of crucible for preparing aluminum vanadium alloy by aluminothermic reaction and its preparation method belong to powder metallurgy technical field.The different particle size aluminum vanadium slag is graded according to set proportion in the present application, by doping high-activity Al2O3 powder, low-melting-point anhydrous Na2CO3 powder, V2O5 powder and MgO powder, two or more of which reduce the self-powder rate of aluminum vanadium slag and forming temperature, the layered vibration form is used for filling, after drying, sintering at 810 DEG C ~ 890 DEG C for 10h ~ 15h, holding, cooling, to obtain the crucible for preparing aluminum vanadium alloy by aluminothermic reaction.The crucible provided by the present application has high density and high sintering strength, and has excellent corrosion resistance and service life.Simultaneously, when the method provided by the present application is used, vacuum or argon protection condition is not needed in sintering process, it can be realized in normal pressure air atmosphere, without vacuum system, the equipment and process are relatively simple, and the manufacturing cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a crucible for preparing aluminum-vanadium alloys by aluminothermic reaction and its preparation method. Background Technology

[0002] Currently, domestic and foreign aluminum-vanadium alloy production enterprises mainly adopt the aluminothermic process (one-step process), the aluminothermic process plus vacuum remelting and refining (two-step process), the vacuum process, and the electro-aluminothermic process as the mainstream vanadium-aluminum alloy production processes. The aluminothermic process generates a large amount of smelting slag, which contains more than 70% Al2O3. If it cannot be effectively utilized, it will cause environmental pollution and waste resources.

[0003] The crucibles used in the aluminothermic reaction are mainly graphite crucibles and alumina crucibles. However, the cost of large, high-purity graphite crucibles customized by aluminum-vanadium alloy manufacturers is extremely high. Therefore, square reaction crucibles are formed by splicing together high-purity graphite plates as furnace linings. Graphite furnace linings have short service lives and cannot be recycled. Furthermore, carbon impurities are more likely to be introduced during the ladle process of aluminum-vanadium alloy production. During the reaction, the uneven distribution of vanadium pentoxide purity in the graphite furnace lining can easily cause splashing, directly reducing the production yield and affecting the chemical composition of the alloy. Although alumina crucibles do not introduce carbon impurities, domestic aluminum-vanadium alloy smelting mainly relies on imports, resulting in high costs. Moreover, domestically produced alumina crucibles have poor thermal shock resistance and are greatly affected by temperature shocks during the aluminothermic reaction. Under conditions of rapid changes in ambient temperature, the strength of the crucible will decrease significantly. After one use, the surface of the crucible often cracks and peels off, rendering it unusable and resulting in a short service life.

[0004] Patent CN104725062A discloses a method for manufacturing a corundum crucible for vacuum induction melting of high-temperature alloys. It uses raw materials such as plate-shaped corundum of different particle sizes, dispersants, and binders, which are mixed uniformly to obtain an alumina slurry. An initiator is added to the alumina slurry, and the mixture is poured into a crucible molding mold, then demolded and dried. The resulting crucible has a low content of impurity elements when melting high-temperature alloys. This patent uses plate-shaped corundum, dispersants, and binders to prepare alumina crucibles through slip casting. However, the chemical stability of alumina crucibles prepared by this method is poor, and their reaction behavior with the alloy is closely related to the alloy composition, limiting the types of alloys that can be used.

[0005] Patent CN119930268A discloses a long-life alumina crucible, its preparation method, and its application. The raw material composition of the alumina crucible includes pretreated quartz particles. The pretreated quartz particles are obtained through a pretreatment process. The pretreatment process involves coating a modifier onto the surface of the molten quartz particles through a granulation process. Specifically, this includes mixing and granulating the molten quartz particles, modifier, and binder, followed by drying to obtain the pretreated quartz particles. However, due to the crystallinity of quartz particles, this alumina crucible still experiences problems such as cracking and peeling during use.

[0006] Therefore, it is particularly urgent to explore a method for recycling aluminum-vanadium alloy smelting slag, reducing the production cost of aluminum-vanadium alloys, and preparing a reusable crucible for aluminothermic reactions. Summary of the Invention

[0007] In view of the technical problems in the above-mentioned aluminothermic process, such as the easy addition of carbon impurities to graphite crucibles, the high cost and short service life of alumina crucibles, and the difficulty in recycling and treating aluminum vanadium slag, this invention provides a crucible for the aluminothermic reaction to prepare aluminum vanadium alloys and its preparation method.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] In one aspect, the present invention provides a crucible for preparing aluminum-vanadium alloys by aluminothermic reaction. The crucible is prepared by mixing two or more of the following: aluminum-vanadium slag with different particle sizes, Al2O3 powder, anhydrous Na2CO3 powder, V2O5 powder, and MgO powder.

[0010] The aluminum vanadium slag of different particle sizes includes large particles, small particles, coarse powder, medium powder and fine powder, with the following particle sizes in descending order: large particles 1mm~3mm, small particles 0.5mm~1mm, coarse powder 0.15mm~0.5mm, medium powder 75μm~150μm, and fine powder <75μm.

[0011] The content of Al2O3 in aluminum vanadium slag is ≥77.6%, the content of CaO is ≥19.7%, the content of V2O5 is ≥0.8%, and the total content of other impurities is ≤1.9%.

[0012] The Al2O3 powder has a particle size of 20nm~500nm and a purity of ≥99.9%, the anhydrous Na2CO3 has a purity of ≥99.8%, the V2O5 has a purity of ≥99%, and the MgO has a purity of ≥98%.

[0013] Another aspect of the present invention provides a method for preparing a crucible for the aluminothermic reaction of aluminum-vanadium alloys, comprising the following steps:

[0014] (1) 84%~90% aluminum vanadium slag and functional powder mixture are ball-milled; wherein, the functional powder mixture is a combination of two or more of Al2O3 powder, anhydrous Na2CO3, V2O5 and MgO powder, the ball milling speed is 100r / min~140r / min, and the ball milling time is 6h~12h.

[0015] Among them, the ratio of large particles to small particles to coarse powder to medium powder to fine powder in aluminum vanadium slag by mass is (0~2):(1~3):(1~4):(1~3):(2~3);

[0016] (2) Add one or more of the following to the obtained ball-milled mixed powder: polyvinyl alcohol (PVA), water, and polyethylene glycol (PEG). The concentration of the polyvinyl alcohol (PVA) solvent is 5wt%~8wt%, and the concentration of the polyethylene glycol (PEG, M... W =4000g / mol) The concentration of the solvent is 25wt%~30wt%, and the amount of organic binder is 7%~12% of the total mass of the mixed powder. After thorough grinding and mixing, the mixture is sieved and granulated.

[0017] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed. The thickness of each layer is 15mm~20mm, the total height of the crucible is 250mm~300mm, the vibration time of each layer is 5min~15min, and after the top is sealed, the vibration continues for 10min~15min to solidify the shape. Then it is taken out and demolded to obtain the crucible preform.

[0018] (4) The crucible preform is air-dried at room temperature for 24h~30h, and then placed in a forced-air drying oven for drying at 100℃~120℃ for 12h~18h to obtain the crucible green blank.

[0019] (5) The crucible blank is placed in a muffle furnace for sintering at a temperature of 810℃~890℃, a sintering time of 10h~15h, a heating rate of 1.5℃ / min~2.5℃ / min, a holding time of 2h~5h, and then cooled to 600℃ at a cooling rate of 1℃ / min~2.5℃ / min, and then cooled to room temperature with the furnace to obtain the crucible used for the aluminothermic reaction to prepare aluminum-vanadium alloy.

[0020] The advantages of this invention compared to existing technologies are:

[0021] (1) The present invention improves the sintering strength by distributing the particle size of aluminum vanadium slag, using large particles with a particle size of 1 mm to 3 mm, small particles with a particle size of 0.5 mm to 1 mm and coarse powder with a particle size of 0.15 mm to 0.5 mm as the skeleton, and medium powder with a particle size of 75 μm to 150 μm and fine powder with a particle size of <75 μm as the void filler to improve the sintering density.

[0022] (2) By doping with two or more of the following: highly active Al2O3 powder, low-melting-point anhydrous Na2CO3 powder (melting point 851℃), V2O5 (690℃) powder and MgO powder, the self-powdering rate and forming temperature of aluminum vanadium slag are reduced. A liquid phase is formed during the sintering process, which improves the sintering strength of the crucible. The prepared crucible is used for the production of aluminum vanadium alloy. Even if the inner wall of the crucible is corroded during the aluminothermic reaction, the phenomenon that carbon impurities will enter the aluminum vanadium alloy due to the use of graphite crucible is avoided. The impurity content of aluminum vanadium alloy is reduced, and the purity of aluminum vanadium alloy products is guaranteed.

[0023] (3) Since the crucible material is aluminum vanadium slag, no vacuum or argon protection is required during the sintering process; it can be done in an atmospheric air atmosphere at normal pressure. Therefore, ordinary high-temperature sintering furnaces can meet the sintering requirements without the need for a vacuum system. The equipment and process are relatively simple, which reduces the manufacturing cost. Attached Figure Description

[0024] Figure 1 The image shows a physical picture of the crucible used for the aluminothermic reaction to prepare aluminum-vanadium alloy in Example 1; where (a) is the front view of the crucible and (b) is the top view of the crucible.

[0025] Figure 2 The images show the crucible after the aluminothermic reaction in Example 2 and the resulting alloy; (a) front view of the crucible, (b) top view of the crucible, (c) back view of the alloy, and (d) front view of the alloy.

[0026] Figure 3 The images show the microstructure of crucibles in different embodiments; (a) Example 1, (b) Example 2, (c) Example 3, and (d) Example 4.

[0027] Figure 4 These are images showing different microstructures of the crucibles obtained in Comparative Example 1; where (a) shows the microstructure. Figure 1 (b) shows the microstructure. Figure 2 .

[0028] Figure 5 This is a comparison chart of the strength of crucibles obtained in different embodiments and Comparative Example 1.

[0029] Figure 6Comparative diagrams of the erosion of the inner wall of crucibles obtained in different embodiments and comparative examples; wherein, (a) Example 1, (b) Example 2, (c) Example 3, (d) Example 4, and (e) Comparative Example 1. Detailed Implementation

[0030] The following detailed description of the implementation examples of the present invention is provided in conjunction with the embodiments. The described implementation examples are some of the best examples of the present invention, but not all of the implementation examples.

[0031] This invention provides a crucible for preparing aluminum-vanadium alloys by aluminothermic reaction. The crucible is prepared by mixing aluminum-vanadium slag with different particle sizes and various powders selected from Al2O3 powder with a particle size of 100nm~500nm and a purity of ≥99.9%, anhydrous Na2CO3 powder with a purity of ≥99.8%, V2O5 powder with a purity of ≥99%, and MgO powder with a purity of ≥98%.

[0032] The aluminum vanadium slag of different particle sizes in this invention includes large particles with a particle size of 1 mm to 3 mm, small particles with a particle size of 0.5 mm to 1 mm, coarse powder with a particle size of 0.15 mm to 0.5 mm, medium powder with a particle size of 75 μm to 150 μm, and fine powder with a particle size of <75 μm. By mass, the ratio of large particles: small particles: coarse powder: medium powder: fine powder is (0~2):(1~3):(1~4):(1~3):(2~3).

[0033] The aluminum vanadium slag in this invention comprises, by mass parts: Al2O3 ≥77.6%, CaO ≥19.7%, V2O5 ≥0.8%, and the total content of other impurities ≤1.9%.

[0034] The crucible provided by this invention for preparing aluminum-vanadium alloys via aluminothermic reaction has a bending strength ≥15MPa, a compressive strength ≥44MPa, and a sintered density ≥2.6g / cm³. 3 The porosity can be as low as 18.5%.

[0035] Another aspect of the present invention provides a method for preparing a crucible for the aluminothermic reaction of aluminum-vanadium alloys, comprising the following steps:

[0036] (1) 84%~90% aluminum vanadium slag and functional powder mixture are ball-milled at a speed of 100r / min~140r / min for 6h~12h to obtain ball-milled mixed powder; wherein, the functional powder mixture is a combination of two or more of Al2O3 powder, anhydrous Na2CO3, V2O5 and MgO powder.

[0037] (2) Add 7% to 12% of the total mass of the ball-milled powder to the obtained mixture, grind and mix thoroughly, and then sieve and granulate; wherein, the organic binder includes 5 wt% to 8 wt% polyvinyl alcohol (PVA), water and 25 wt% to 30 wt% polyethylene glycol (PEG, M W One or more of the following: (e.g., 4000 g / mol);

[0038] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed: the thickness of each layer is 15mm~20mm, the total height of the crucible is 250mm~300mm, and the vibration time of each layer is 5min~15min; after the top is sealed, continue to vibrate for 10min~15min to solidify the shape, and then take it out for demolding to obtain the crucible preform;

[0039] (4) Allow the crucible preform to air dry naturally at room temperature for 24-30 hours, then place it in a forced-air drying oven and dry at 100-120°C for 12-18 hours to obtain the crucible green blank.

[0040] (5) Place the crucible blank into a muffle furnace and heat it to 810℃~890℃ at a heating rate of 1.5℃ / min~2.5℃ / min. After sintering for 10h~15h, hold it at the temperature for 2h~5h. Then, cool it to 600℃ at a rate of 1℃ / min~2.5℃ / min and cool it to room temperature with the furnace to obtain the crucible used for the aluminothermic reaction to prepare aluminum-vanadium alloy.

[0041] The Al2O3 powder, anhydrous Na2CO3 powder, V2O5 powder, and MgO powder used in the embodiments of this invention are all commercially available products.

[0042] In this embodiment of the invention, the equipment used to observe the microscopic morphology is an SSX-550 scanning electron microscope.

[0043] In this embodiment of the invention, the porosity is measured and calculated using the Archimedes displacement method and a DZF-6050 vacuum drying oven.

[0044] In this embodiment of the invention, the method for measuring flexural and compressive strength is to calculate the flexural and compressive strength after testing with a CMT-50 electronic universal testing machine.

[0045] This invention improves the compactness of aluminum vanadium slag during low-temperature sintering by re-particle size distribution of the by-product aluminum vanadium slag generated during the production of aluminum vanadium alloys.

[0046] This invention creatively utilizes multiple components from Al2O3 powder, anhydrous Na2CO3, V2O5, and MgO as liquid-phase sintering fluxes to improve the stability of aluminum-vanadium slag particles during crucible sintering, enhance the bonding between the aluminum-vanadium slag particles and fine powder components, thereby improving the mechanical properties of the crucible made from aluminum-vanadium slag, such as flexural and compressive strength. This ultimately increases the service life and stability of the crucible, ensuring that the performance of the aluminum-vanadium slag crucible fully meets the requirements for aluminum-vanadium alloy production via the aluminothermic process. This invention enables the recycling and reuse of aluminum-vanadium slag, requires a lower sintering temperature and less energy, effectively reducing costs. Furthermore, the preparation process of this invention is simple and easy to promote and use.

[0047] Example 1:

[0048] This embodiment provides a crucible for the aluminothermic reaction preparation of aluminum-vanadium alloys, including the following steps:

[0049] (1) Add 84% by mass of aluminum vanadium slag (Al2O3 content ≥77.6%, CaO content ≥19.7%, V2O5 content ≥0.8%, and total content of other impurities ≤1.9%), 7% by mass of Al2O3 powder (particle size 500nm, purity ≥99.9%), and 9% by mass of anhydrous Na2CO3 powder (purity ≥99.8%) to a ball mill jar and ball mill at 100r / min for 6h to obtain a mixed powder; wherein, the aluminum vanadium slag powder, by mass, has a ratio of large particles: small particles: coarse powder: medium powder: fine powder = 1:2:1:3:3;

[0050] (2) Add an organic binder consisting of 30wt% polyethylene glycol (PEG) and 2% water at a mass fraction of 7% of the mixed powder to the obtained mixture, grind and mix thoroughly, and then sieve and granulate.

[0051] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed: the thickness of each layer is 20mm, the total height of the crucible is 280mm, and the vibration time of each layer is 15min; after the top is sealed, continue to vibrate for 15min to solidify the shape, then take it out and demold it to obtain the crucible preform.

[0052] (4) The crucible preform is air-dried at room temperature for 24 hours, and then placed in a forced-air drying oven at 100°C for 18 hours to obtain the crucible green blank;

[0053] (5) Place the crucible blank into a muffle furnace, heat it to 810°C at a rate of 2.5°C / min, sinter for 12 hours, hold for 5 hours, then cool it to 600°C at a rate of 2°C / min and then cool it to room temperature with the furnace to obtain a crucible for the aluminothermic reaction to prepare aluminum-vanadium alloys (structure as shown in the figure). Figure 1 (As shown).

[0054] Example 2:

[0055] This embodiment provides a crucible for the aluminothermic reaction preparation of aluminum-vanadium alloys, including the following steps:

[0056] (1) Add 87% by mass of aluminum vanadium slag (Al2O3 content ≥77.6%, CaO content ≥19.7%, V2O5 content ≥0.8%, and total content of other impurities ≤1.9%), 5% by mass of Al2O3 powder (particle size 200nm, purity ≥99.9%), 7% by mass of anhydrous Na2CO3 powder (purity ≥99.8%), and 1% by mass of V2O5 powder (purity ≥99%) to a ball mill jar and ball mill at 110r / min for 8h to obtain mixed powder; wherein, the ratio of aluminum vanadium slag powder by mass is large particles: small particles: coarse powder: medium powder: fine powder = 1.5:1.5:1.5:3:2.5;

[0057] (2) Add an organic binder consisting of 5% by mass of polyvinyl alcohol (PVA) solvent and 3% by mass of water to the obtained mixture, grind and mix thoroughly, and then sieve and granulate.

[0058] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed: the thickness of each layer is 15mm, the total height of the crucible is 300mm, and the vibration time of each layer is 5min; after the top is sealed, continue to vibrate for 10min to solidify the shape, then take it out and demold it to obtain the crucible preform.

[0059] (4) The crucible preform is air-dried at room temperature for 28 hours, and then placed in a forced-air drying oven at 120°C for 16 hours to obtain the crucible green blank;

[0060] (5) Place the crucible blank into a muffle furnace, heat it to 850°C at a rate of 1.5°C / min, sinter for 14 hours, hold for 2 hours, then cool it to 600°C at a rate of 1.5°C / min and cool it to room temperature with the furnace to obtain a crucible for the aluminothermic reaction to prepare aluminum-vanadium alloys (e.g. Figure 2 (as shown in (a) and (b)). Using the crucible prepared in this embodiment, an aluminum-vanadium alloy was prepared, and the resulting alloy is as follows. Figure 2 As shown in (c) and (d), when preparing aluminum-vanadium alloys using the crucible prepared in this embodiment, after slag-gold separation, a small amount of alloy enters the slag, while most of the alloy remains intact, and the area of ​​the gold oxide film formed on the alloy surface is relatively small.

[0061] Example 3:

[0062] This embodiment provides a crucible for the aluminothermic reaction preparation of aluminum-vanadium alloys, including the following steps:

[0063] (1) Add 89% by mass of aluminum vanadium slag (Al2O3 content ≥77.6%, CaO content ≥19.7%, V2O5 content ≥0.8%, and total content of other impurities ≤1.9%), 4.4% by mass of Al2O3 powder (particle size 350nm, purity ≥99.9%), 6% by mass of anhydrous Na2CO3 powder (purity ≥99.8%), 0.3% by mass of MgO powder (purity ≥98%), and 0.3% by mass of V2O5 powder (purity ≥99%) to a ball mill jar and ball mill at a speed of 120r / min for 12h to obtain a mixed powder; wherein, the aluminum vanadium slag powder, by mass, has a ratio of small particles: coarse powder: medium powder: fine powder = 3:4:1:2;

[0064] (2) Add an organic binder consisting of 3% by mass of 6 wt% polyvinyl alcohol (PVA) and 6% by mass of 25 wt% polyethylene glycol (PEG) to the obtained mixture, grind and mix thoroughly, and then sieve and granulate.

[0065] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed: the thickness of each layer is 18mm, the total height of the crucible is 270mm, and the vibration time of each layer is 10min; after the top is sealed, continue to vibrate for 12min to solidify the shape, then take it out and demold it to obtain the crucible preform;

[0066] (4) The crucible preform is air-dried at room temperature for 30 hours, and then placed in a forced-air drying oven at 110°C for 12 hours to obtain the crucible green blank;

[0067] (5) Place the crucible blank into a muffle furnace, heat it to 870°C at a rate of 2°C / min, sinter for 15 hours and hold for 3 hours, then cool it to 600°C at a rate of 1°C / min and then cool it to room temperature with the furnace to obtain a crucible for the aluminothermic reaction to prepare aluminum-vanadium alloy.

[0068] Example 4:

[0069] This embodiment provides a crucible for the aluminothermic reaction preparation of aluminum-vanadium alloys, including the following steps:

[0070] (1) Add 90% by mass of aluminum vanadium slag (Al2O3 content ≥77.6%, CaO content ≥19.7%, V2O5 content ≥0.8%, and total content of other impurities ≤1.9%), 3.3% by mass of Al2O3 powder (particle size 100nm, purity ≥99.9%), 6.5% by mass of anhydrous Na2CO3 powder (purity ≥99.8%), and 0.2% by mass of V2O5 powder (purity ≥99%) to a ball mill jar and ball mill at a speed of 140r / min for 10h to obtain a mixed powder; wherein, the aluminum vanadium slag powder, by mass, has a ratio of large particles: small particles: coarse powder: medium powder: fine powder = 2:1:3:2:2;

[0071] (2) Add an organic binder consisting of 4% by mass of 7wt% polyvinyl alcohol (PVA) solvent, 3% by mass of 30wt% polyethylene glycol (PEG) solvent and 2% by mass of the mixed powder to the obtained mixture, grind and mix thoroughly, and then sieve and granulate.

[0072] (3) The granulated mixture is loaded into the crucible mold cavity and the filling operation is carried out in a layered vibration form on the mechanical vibration platform until the top is sealed. The thickness of each layer is 15mm, the total height of the crucible is 270mm, and the vibration time of each layer is 12min. After the top is sealed, vibration is continued for 14min to solidify the shape. Then it is taken out and demolded to obtain the crucible preform.

[0073] (4) The crucible preform is air-dried at room temperature for 26 hours, and then placed in a forced-air drying oven at 105°C for 14 hours to obtain the crucible green blank;

[0074] (5) Place the crucible blank into a muffle furnace, heat it to 890°C at a rate of 2.5°C / min, sinter for 11 hours and hold for 4 hours, then cool it to 600°C at a rate of 2.5°C / min and then cool it to room temperature with the furnace to obtain a crucible for the aluminothermic reaction to prepare aluminum-vanadium alloy.

[0075] Comparative Example 1:

[0076] The process flow of this comparative example is the same as that of Example 1, except that only 7% by mass of Al2O3 powder (particle size 500nm, purity ≥99.9%) was added, and anhydrous Na2CO3 powder (purity ≥99.8%) was not added. The mass ratio of aluminum vanadium slag was adjusted to 93%, the particle size distribution remained unchanged, the sintering temperature was adjusted to 1500℃, and other conditions were the same.

[0077] Comparative Example 2:

[0078] The process flow of this comparative example is the same as that of Example 2, except that 5% by mass of Al2O3 powder (particle size 200nm, purity ≥99.9%) and 1% by mass of V2O5 powder (purity ≥99%) are added, anhydrous Na2CO3 powder (purity ≥99.8%) is not added, the mass ratio of aluminum vanadium slag is adjusted to 94%, the particle size distribution remains unchanged, the sintering temperature is adjusted to 1400℃, and other conditions are the same.

[0079] Comparative Example 3:

[0080] The process flow of this comparative example is the same as that of Example 3, except that only 4.4% of Al2O3 powder (particle size 350nm, purity ≥99.9%), 0.3% of MgO powder (purity ≥98%), and 0.3% of V2O5 powder (purity ≥99%) by mass are added. Anhydrous Na2CO3 powder (purity ≥99.8%) is not added. The mass ratio of aluminum vanadium slag is adjusted to 95%, the particle size distribution remains unchanged, the sintering temperature is adjusted to 1300℃, and other conditions are the same.

[0081] Performance characterization:

[0082] The microstructure of the crucibles prepared in Examples 1-4 and Comparative Example 1 of this invention was observed, and the results are as follows: Figure 3 , 4 As shown in the figure, without the addition of anhydrous Na2CO3 powder (purity ≥99.8%), aluminum vanadium slag particles of different sizes failed to agglomerate effectively, resulting in poor density and high porosity. However, the addition of anhydrous Na2CO3 powder (purity ≥99.8%) and V2O5 powder (purity ≥99%) formed the NaVO3 phase and Na2CO3 liquid phase, which effectively agglomerated aluminum vanadium slag particles and improved crucible strength.

[0083] To further demonstrate the performance and strength of the crucible of the present invention, the crucibles prepared in Examples 1-4 and Comparative Examples 1-3 were tested for flexural strength, compressive strength, sintering density, and porosity. The test results are shown in Table 1, where the strength comparison results of the crucibles obtained from different examples and Comparative Example 1 are as follows. Figure 5 As shown. Simultaneously, crucibles with a wall thickness of 50 mm prepared in Examples 1-4 and Comparative Example 1 were subjected to aluminothermic reaction under the same conditions. The resulting crucibles are shown below. Figure 6 As shown in (a) to (e), the degree of erosion of its inner wall was tested, and the results are shown in Table 2.

[0084] ;

[0085] ;

[0086] As shown in Table 1, by adding anhydrous Na2CO3 powder, the crucible firing temperature can be reduced to 850℃, while crucibles without anhydrous Na2CO3 powder require firing at 1500℃. Furthermore, the crucible prepared by sintering at 810℃~890℃ exhibits very high compressive strength and sintering density, demonstrating excellent mechanical properties. By adding multiple components of Al2O3 powder, anhydrous Na2CO3 powder, V2O5 powder, and MgO powder as liquid-phase sintering aids, the aluminum vanadium slag exhibits superior performance at relatively low sintering temperatures.

[0087] Table 2 shows the degree of erosion of the inner wall of different crucibles after aluminothermic reaction. After adding anhydrous Na2CO3 powder and V2O5 powder, the degree of erosion damage to the inner wall of the crucible caused by the aluminothermic reaction decreased from 23%~29% to 10%~14%. Examples 1, 3 and 4 show that as the amount of anhydrous Na2CO3 powder and nano Al2O3 powder added increases, the erosion resistance of the crucible is improved, and the degree of erosion damage to the inner wall decreases from 10%~14% to 4%~6%. Examples 2, 3 and 4 show that as the amount of V2O5 powder added increases, the erosion resistance of the crucible is further improved, and the degree of erosion damage to the inner wall decreases from 10%~14% to 2%~4%, which greatly improves the service life of the crucible.

[0088] The present invention has been described in detail above. The above embodiments are only the optimal implementation results of the present invention. After reading the present invention, those skilled in the art can conduct various changes, modifications, substitutions and variations of the implementation cases of the present invention based on the basic idea of ​​the present invention. All these equivalent forms fall within the scope defined by the present invention.

Claims

1. A crucible for the aluminothermic reaction preparation of aluminum-vanadium alloys, characterized in that, The crucible was prepared by mixing aluminum vanadium slag of different particle sizes with Al2O3 powder, anhydrous Na2CO3 powder, V2O5 powder and MgO powder. The aluminum vanadium slag of different particle sizes includes large particles, small particles, coarse powder, medium powder and fine powder, with the following particle sizes in descending order: large particles 1mm~3mm, small particles 0.5mm~1mm, coarse powder 0.15mm~0.5mm, medium powder 75μm~150μm, and fine powder <75μm. By mass, the ratio of large particles to small particles to coarse powder to medium powder to fine powder in aluminum vanadium slag is (0~2):(1~3):(1~4):(1~3):(2~3); The method for preparing the crucible includes the following steps: (1) A mixture of aluminum vanadium slag and functional powder is ball-milled to obtain a mixed powder; wherein the functional powder mixture is a combination of Al2O3 powder, anhydrous Na2CO3, V2O5 and MgO powder. (2) Add an organic binder to the mixed powder, grind and mix thoroughly, and then sieve and granulate. (3) The granulated mixture is loaded into the crucible mold, and the material is adjusted by layered vibration on the mechanical platform until the top is sealed. Then the material is shaped and removed from the mold to obtain the crucible preform. (4) After the crucible preform is naturally air-dried at room temperature, it is dried to obtain the crucible green blank; (5) The crucible blank is placed in a muffle furnace and sintered at 850℃~890℃. After holding at the temperature, it is cooled down to 600℃ and cooled with the furnace to obtain a crucible for the aluminothermic reaction to prepare aluminum-vanadium alloy. In step (3), when the seasoning operation is carried out in the form of layered vibration, the thickness of each layer is 15mm~20mm, the vibration time of each layer is 5min~15min, and the total height of the crucible is 250mm~300mm; The shaping process employs vibration shaping, with a vibration shaping time of 10 to 15 minutes. Aluminum vanadium slag accounts for 84% to 90% of the mass of the mixed powder.

2. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 1, characterized in that, The content of Al2O3 in aluminum vanadium slag is ≥77.6%, the content of CaO is ≥19.7%, the content of V2O5 is ≥0.8%, and the total content of other impurities is ≤1.9%. The Al2O3 powder has a particle size of 20nm~500nm.

3. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 1, characterized in that, In step (1), the ball milling speed is 100r / min~140r / min and the ball milling time is 6h~12h.

4. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 1, characterized in that, In step (2), the organic binder is one or both of polyvinyl alcohol and polyethylene glycol; the amount of organic binder is 7% to 12% of the total mass of the mixed powder.

5. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 4, characterized in that, The concentration of polyvinyl alcohol is 5wt%~8wt%, and the concentration of polyethylene glycol is 25wt%~30wt%.

6. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 1, characterized in that, In step (4), the natural air-drying time is 24h~30h; The drying temperature is 100℃~120℃, and the drying time is 12h~18h.

7. The crucible for preparing aluminum-vanadium alloys by aluminothermic reaction according to claim 1, characterized in that, In step (5), the heating rate before sintering is 1.5℃ / min~2.5℃ / min, and the sintering time is 10h~15h; The heat preservation time is 2 hours to 5 hours; The cooling rate is 1℃ / min to 2.5℃ / min.

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