Silicon nitride bonded silicon carbide ceramic material tube for aluminum alloy die casting and preparation method

Abstract

The present invention relates to the technical field of aluminum alloy die-casting, and more particularly to a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die-casting and a preparation method thereof. The silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die-casting has an annular structure with an open ring wall. The tube is made of silicon nitride-bonded silicon carbide ceramic and is prepared from 45 to 85 parts by weight of a mixed powder, 3 to 10 parts by weight of a reinforcing agent, and 15 to 40 parts by weight of a conditioning agent solution; the mixed powder comprises elemental silicon powder, silicon nitride powder, and silicon carbide powder. Due to the in-situ SiTi2N4 reinforcement phase, the feed tube exhibits excellent wear resistance, thermal shock resistance, and low thermal conductivity, making it adaptable to the service environment of ultra-high pressure casting machines and significantly improving the production efficiency of high-pressure casting machines. The reduced thermal conductivity of the ceramic material reduces heat loss, enhances the temperature control capability of the aluminum alloy fluid within the feed tube, and ensures the product's high performance and stability.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy die casting technology, and in particular to a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting and its preparation method. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles and aerospace, higher requirements have been placed on lightweight, high-toughness, and corrosion-resistant castings. For aluminum alloy parts, the forming processes of high-strength, high-toughness corrosion-resistant alloys, wrought alloys, and large, complex alloy parts have become a research hotspot for lightweight alloys.

[0003] Traditional casting processes, such as gravity casting and high-pressure casting (500t), produce aluminum alloys with low tensile strength and low elongation in the as-cast state. Given the increasing demand for high-strength, high-toughness, and lightweight castings, the advantages of using ultra-high-pressure casting (5000t and above) to manufacture aluminum alloy parts have gained attention.

[0004] To meet the requirements of continuous operation and improved production efficiency of high-pressure die casting machines (especially large-tonnage die casting machines of 5000t and above), higher standards have been set for the performance of the feed pipe at the die casting machine's feed port. Most existing high-pressure die casting machine feed pipes are made of heat-resistant steel (H13 metal), which is prone to deformation under continuous production at operating temperatures, exhibits poor wear resistance, and poor heat insulation, requiring the use of cooling facilities. This not only causes heat loss and energy waste but also leads to premature solidification of the aluminum alloy in the feed pipe, causing wear on the inner wall of the pipe and, in severe cases, blockage. Furthermore, it negatively impacts the crystallization and forming of the aluminum alloy during die casting, affecting the strength and toughness of the die castings, reducing yield, and increasing production costs.

[0005] Silicon nitride-bonded silicon carbide is a high-quality refractory material with excellent corrosion resistance, erosion resistance, and wear resistance. Compared to other non-oxide refractory materials (such as recrystallized silicon carbide), it has a price advantage, making it widely used in non-ferrous metallurgy, steel smelting, petrochemicals, and automobile manufacturing. However, current production processes for silicon nitride-bonded silicon carbide use refractory-grade raw materials, and the mixing and molding processes are relatively outdated. This results in silicon nitride-bonded silicon carbide with poor uniformity and low-temperature performance, making it difficult to apply in high-pressure casting of aluminum alloys.

[0006] Therefore, we propose a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting and its preparation method to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting and its preparation method.

[0008] A silicon nitride-bonded silicon carbide ceramic tube for die casting of aluminum alloys, the tube is annular with an open annular wall, the material is silicon nitride-bonded silicon carbide ceramic, and it is made of 45-85 parts by weight of mixed powder, 3-10 parts by weight of reinforcing agent and 15-40 parts by weight of quenching agent solution.

[0009] The mixed powder is composed of 35-55 parts by weight of elemental silicon powder, 5-10 parts by weight of silicon nitride powder, and 5-20 parts by weight of silicon carbide powder.

[0010] The reinforcing agent powder comprises 1 to 3 parts by weight of titanium nitride powder, 1 to 2 parts by weight of titanium carbide powder, and 1 to 5 parts by weight of titanium-silicon alloy.

[0011] Preferably, the purity of the elemental silicon powder is ≥99wt% and the particle size is 200-600 mesh, the purity of the silicon nitride powder is ≥99wt% and the particle size is 600-1000 mesh, and the purity of the silicon carbide powder is ≥99wt% and the particle size is 600-1000 mesh.

[0012] Preferably, the purity of the reinforcing agent powder is ≥98wt%, and the particle size is 200-400 mesh.

[0013] Preferably, the mass ratio of water, surfactant and HPMC in the conditioning agent solution is 1:0.02-0.05:0.15-0.25.

[0014] A method for preparing a silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting includes the following steps:

[0015] S1. Mix the mixed powder and the reinforcing agent powder separately under argon or nitrogen protection for 12 hours and set aside. Place the mixed powder with anhydrous ethanol and high-speed ball milling beads into a high-speed ball mill under atmosphere protection and grind for 1 to 4 hours. Then add the reinforcing agent powder and continue grinding for 2 to 8 hours to obtain a slurry.

[0016] S2. The slurry obtained in step S1 is dried at 60-150℃ using a spray granulation device to obtain a uniform and stable powder. A conditioning agent solution of 25-35 wt% of the total mass of the powder is added, and the mixture is kneaded in a kneader for 0.5-6 hours to obtain mud.

[0017] S3. The clay obtained in step S2 is made into a ceramic tube blank and dried under constant temperature and humidity conditions.

[0018] S4. Place the ceramic tube blank obtained in step S3 in a debinding furnace and heat it to 600-1050℃ at a heating rate of 1-5℃ / min. Hold it at this temperature for 0.5-3h to obtain a silicon nitride bonded silicon carbide ceramic tube blank.

[0019] S5. Place the ceramic tube blank obtained in step S4 in a high-temperature sintering furnace. Under a nitrogen atmosphere, heat the material to 1050℃ at a heating rate of 5-15℃ / min and hold for 0.5-1h. Then heat the material to 1200℃ at a heating rate of 5-15℃ / min and hold for 1-3h. Next, heat the material to 1410-1450℃ at a heating rate of 5-15℃ / min and hold for 2-5h. Finally, heat the material to 1500-1650℃ at a heating rate of 5-10℃ / min and hold for 1-4h to obtain a novel silicon nitride-bonded silicon carbide ceramic tube.

[0020] Preferably, in step S1, the rotation speed of the high-speed ball mill is 250 r / min to 350 r / min, the ball milling time is 6 to 9 h, the mass ratio of the mixed powder to anhydrous ethanol and high-speed ball milling beads is 1:4 to 8:2 to 3, the high-speed ball milling beads are one or more of agate ball milling beads, stainless steel ball milling beads and corundum ball milling beads, and the protective atmosphere is vacuum, argon, nitrogen or a combination of the above atmospheres.

[0021] Preferably, in step S2, the slurry is dried using a spray granulation device at 80–110°C.

[0022] Preferably, in step S3, the clay is placed in a clay refining machine to obtain homogeneous clay, and then placed in an extrusion molding machine to obtain a ceramic tube blank.

[0023] Preferably, in step S3, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing, and the isostatic pressing pressure is 150-200 MPa.

[0024] Preferably, in step S4, when the ceramic blank is sintered in the debinding furnace, the atmosphere is one or more of vacuum, argon, and nitrogen.

[0025] The beneficial effects of this invention are:

[0026] 1. Ceramic tubing has excellent chemical corrosion resistance, which can increase the service life of tubing (especially large-tonnage die-casting machines of 5000t and above) by 3 to 4 times. It avoids contamination of the alloy liquid by the tubing material. At the same time, ceramic tubing does not deform in the hot state, has high hardness and good wear resistance, and its hardness and wear resistance do not undergo thermal decay. This makes the die-casting operation more stable, and the alloy melt does not flow back when the injection head is pressurized and pushed. It can also apply greater pressure.

[0027] 2. The thermal conductivity of the ceramic lining is 1 / 2 to 1 / 3 that of the existing H13 metal material, reducing heat loss of the alloy molten metal in the tube and lowering the casting temperature of the alloy molten metal by about 20 to 40°C. No cooling facilities are required during use, saving energy, enabling semi-solid die casting, increasing the density and strength of die castings, improving die casting quality, and increasing die casting efficiency by about 20 to 40%. At the same time, the production cycle of silicon nitride-bonded silicon carbide ceramic composite tubes is short, approximately 5 to 8 days, which is about 2 / 3 less than the 19 to 23 days production time of traditional metal tubes, better meeting emergency needs and reducing spare parts inventory.

[0028] 3. During the high-temperature heat treatment process, SiTi2N4 is generated in situ. This is a superhard material with strong covalent bonds and metallic properties. It reduces the mechanical wear of the tube by the molten aluminum during the high-pressure semi-solid die casting process. At the same time, SiTi2N4 can form a good chemical bond with silicon nitride and silicon carbide, which improves the comprehensive mechanical properties of the tube and keeps the molten aluminum clean. This can greatly improve the service life of the tube and the die casting efficiency.

[0029] 4. In-situ spinel-type SiTi2N4 has a metallic banded structure, which can enhance and toughen silicon nitride-bonded silicon carbide ceramic tubes, while significantly improving the thermal shock stability of the composite material and significantly increasing its service life. Detailed Implementation

[0030] The present invention will be further explained below with reference to specific embodiments.

[0031] Example 1:

[0032] A silicon nitride-bonded silicon carbide ceramic tube for die casting of aluminum alloys is provided. The tube is annular with an open annular wall. The material is silicon nitride-bonded silicon carbide ceramic, which is composed of 58 parts by weight of mixed powder, 8 parts by weight of reinforcing agent and 24.8 parts by weight of quenching and tempering agent solution.

[0033] The mixed powder consists of 40 parts by weight of elemental silicon powder, 8 parts by weight of silicon nitride powder, and 10 parts by weight of silicon carbide powder.

[0034] The purity of the elemental silicon powder is ≥99wt%, and the particle size is 400 mesh; the purity of the silicon nitride powder is ≥99wt%, and the particle size is 800 mesh; the purity of the silicon carbide powder is ≥99wt%, and the particle size is 8000 mesh; the purity of the reinforcing agent powder is ≥98wt%, and the particle size is 300 mesh.

[0035] The reinforcing agent powder comprises 3 parts by weight of titanium nitride powder, 2 parts by weight of titanium carbide powder, and 3 parts by weight of titanium-silicon alloy.

[0036] The conditioning solution consists of 20 parts by weight of water, 0.8 parts by weight of surfactant and 4 parts by weight of HPMC.

[0037] A method for preparing a silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting includes the following steps:

[0038] S1. Mix the mixed powder and reinforcing agent powder separately under argon protection for 12 hours to prevent oxidation of the raw materials. Accurately weigh the mixed powder with anhydrous ethanol and high-speed ball milling beads according to the mass ratio of 1:6:2.5, and grind them in a high-speed ball mill at 300 r / min under argon protection for 2 hours. Then add the reinforcing agent powder and continue grinding for 4 hours to obtain a slurry. The high-speed ball milling beads are agate ball milling beads.

[0039] S2. The slurry obtained in step S1 is dried at 100°C using a spray granulation device to obtain a uniform and stable powder. A conditioning agent solution is added, and the powder is kneaded in a kneader for 3 hours to obtain mud.

[0040] S3. The obtained clay is placed in a clay mixing machine to make clay homogeneous clay, which is then placed in an extrusion molding machine to obtain a ceramic tube blank. The blank is then placed in an isostatic press and isostatically pressed at 180MPa to obtain a dense ceramic tube blank, which is then dried under constant temperature and humidity conditions.

[0041] S4. Place the ceramic tube blank obtained in step S3 in a debinding furnace with a nitrogen atmosphere, heat it to 700°C at a heating rate of 3°C / min, and hold it for 2 hours to obtain a silicon nitride bonded silicon carbide ceramic tube blank.

[0042] S5. Place the ceramic tube blank obtained in step S4 in a high-temperature sintering furnace, and heat it to 1430°C at a heating rate of 10°C / min under a nitrogen atmosphere, hold it for 3 hours, and then heat it to 1600°C at a heating rate of 8°C / min, hold it for 3 hours to obtain a novel silicon nitride-bonded silicon carbide ceramic tube.

[0043] Example 2:

[0044] A silicon nitride-bonded silicon carbide ceramic tube for die casting of aluminum alloys is provided. The tube is annular with an open annular wall. The material is silicon nitride-bonded silicon carbide ceramic, which is prepared by 74 parts by weight of mixed powder and 26 parts by weight of quenching agent solution.

[0045] The mixed powder consists of 35 parts by weight of elemental silicon powder, 10 parts by weight of silicon nitride powder, 20 parts by weight of silicon carbide powder, and 9 parts by weight of reinforcing agent.

[0046] The purity of the elemental silicon powder is ≥99wt%, and the particle size is 400 mesh; the purity of the silicon nitride powder is ≥99wt%, and the particle size is 800 mesh; the purity of the silicon carbide powder is ≥99wt%, and the particle size is 8000 mesh; the purity of the reinforcing agent powder is ≥98wt%, and the particle size is 300 mesh.

[0047] The reinforcing agent powder comprises 3 parts by weight of titanium nitride powder, 2 parts by weight of titanium carbide powder, and 4 parts by weight of titanium-silicon alloy.

[0048] The conditioning solution consists of 20 parts by weight of water, 1 part by weight of surfactant, and 5 parts by weight of HPMC.

[0049] A method for preparing a silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting includes the following steps:

[0050] S1. Mix the mixed powder and reinforcing agent powder separately under nitrogen protection for 12 hours to prevent oxidation of the raw materials. Accurately weigh the mixed powder with anhydrous ethanol and high-speed grinding beads according to the mass ratio of 1:6:2.5, and grind it in a high-speed ball mill at 300 r / min under nitrogen protection for 2 hours. Then add the reinforcing agent powder and continue grinding for 4 hours to obtain a slurry. The high-speed grinding beads are stainless steel grinding beads.

[0051] S2. The slurry obtained in step S1 is dried at 100°C using a spray granulation device to obtain a uniform and stable powder, which is then kneaded in a mixer for 4 hours to obtain mud.

[0052] S3. The obtained clay is placed in a clay mixing machine to make clay homogeneous clay, which is then placed in an extrusion molding machine to obtain a ceramic tube blank, and then placed in an isostatic press to be isostatically pressed at 180MPa to obtain a dense ceramic tube blank.

[0053] S4. Place the ceramic tube blank obtained in step S3 in a debinding furnace with a nitrogen atmosphere, heat it to 800℃ at a heating rate of 3℃ / min, and hold it for 2 hours to obtain a silicon nitride bonded silicon carbide ceramic tube blank.

[0054] S5. Place the ceramic tube blank obtained in step S4 in a high-temperature debinding furnace, and heat it to 1440°C at a heating rate of 10°C / min under a nitrogen atmosphere. Hold it at this temperature for 3 hours, and then heat it to 1620°C at a heating rate of 5-10°C / min. Hold it at this temperature for 2.5 hours to obtain a novel silicon nitride-bonded silicon carbide ceramic tube.

[0055] Example 3:

[0056] A silicon nitride-bonded silicon carbide ceramic tube for die casting of aluminum alloys is provided. The tube is annular with an open annular wall. The material is silicon nitride-bonded silicon carbide ceramic, which is prepared by 75 parts by weight of mixed powder and 24.8 parts by weight of tempering agent solution.

[0057] The mixed powder consists of 40 parts by weight of elemental silicon powder, 10 parts by weight of silicon nitride powder, 15 parts by weight of silicon carbide powder and 10 parts by weight of reinforcing agent.

[0058] The purity of the elemental silicon powder is ≥99wt%, and the particle size is 400 mesh; the purity of the silicon nitride powder is ≥99wt%, and the particle size is 800 mesh; the purity of the silicon carbide powder is ≥99wt%, and the particle size is 8000 mesh; the purity of the reinforcing agent powder is ≥98wt%, and the particle size is 300 mesh.

[0059] The reinforcing agent powder comprises 3 parts by weight of titanium nitride powder, 2 parts by weight of titanium carbide powder, and 5 parts by weight of titanium-silicon alloy.

[0060] The conditioning solution consists of 20 parts by weight of water, 0.8 parts by weight of surfactant and 4 parts by weight of HPMC.

[0061] A method for preparing a silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting includes the following steps:

[0062] S1. Mix the mixed powder and reinforcing agent powder separately under nitrogen protection for 12 hours to prevent oxidation of the raw materials. Accurately weigh the mixed powder with anhydrous ethanol and high-speed ball milling beads according to the mass ratio of 1:6:2.5, and grind them in a high-speed ball mill at a speed of 300 r / min under nitrogen protection for 2 hours. Then add the reinforcing agent powder and continue grinding for 4 hours to obtain a slurry. The high-speed ball milling beads are corundum ball milling beads.

[0063] S2. The slurry obtained in step S1 is dried at 80°C using a spray granulation device to obtain a uniform and stable powder. The powder is then kneaded in a mixer for 3 hours to obtain mud.

[0064] S3. The obtained clay is placed in a clay mixing machine to make clay homogeneous clay, which is then placed in an extrusion molding machine to obtain a ceramic tube blank, and then placed in an isostatic press to be isostatically pressed at 180MPa to obtain a dense ceramic tube blank.

[0065] S4. Place the ceramic tube blank obtained in step S3 in a debinding furnace with a nitrogen atmosphere, heat it to 800℃ at a heating rate of 5℃ / min, and hold it for 1.5h to obtain a silicon nitride bonded silicon carbide ceramic tube blank.

[0066] S5. Place the ceramic tube blank obtained in step S4 in a high-temperature debinding furnace, and heat it to 1430°C at a heating rate of 10°C / min under a nitrogen atmosphere. Hold it at this temperature for 4 hours, and then heat it to 1600°C at a heating rate of 8°C / min. Hold it at this temperature for 2 hours to obtain a novel silicon nitride-bonded silicon carbide ceramic tube.

[0067] Comparative example:

[0068] A silicon nitride-bonded silicon carbide tubing is prepared from the following raw materials in parts by weight:

[0069] 10 parts by weight of elemental silicon powder, 20 parts by weight of silicon nitride powder, and 20 parts by weight of silicon carbide powder.

[0070] Its preparation method includes the following steps:

[0071] S1. Mix elemental silicon powder, silicon nitride powder and silicon carbide powder at 60°C for 1.5 hours to obtain a uniform mixture;

[0072] S2. The mixture obtained in step S1 is dried at a temperature of 200℃ and a humidity of 3% for 5 hours, and then sealed and trapped for 36 hours to obtain the shaped mixture.

[0073] S3. The mixture obtained in step S2 is shaped by friction forming to obtain a blank of the tube.

[0074] S4. Place the blank of the tube obtained in step S3 into a high-temperature furnace. The high-temperature furnace is a box-type carbonization furnace. Sintering is carried out under the protection of nitrogen atmosphere. The temperature is raised to 1200℃ at a heating rate of 60℃ / h and held for 2h to obtain the tube.

[0075] The mechanical properties and thermal shock stability of the silicon nitride-bonded silicon carbide ceramic tubing in Examples 1 to 3 and the comparative example were tested, and the test results are as follows:

[0076]

[0077] Among them, hardness is Vickers hardness at room temperature, and the testing standard is GB / T 16534-2009; coefficient of thermal expansion is the linear coefficient of thermal expansion between 20℃ and 300℃, and the testing standard is YS / T 63.4-2006; thermal shock cracking test is the residual strength retention rate after water cooling at 1000℃, and the testing standard is YB 4018-91; thermal conductivity is tested according to GB / T 39862-2021; and abrasion resistance is abrasion resistance at room temperature, and the testing standard is GB / T 18301-2012.

[0078] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A silicon nitride-bonded silicon carbide ceramic tube for die casting of aluminum alloys, characterized in that, The tube is annular with an open ring wall. The material is silicon nitride-bonded silicon carbide ceramic, which is prepared from 45 to 85 parts by weight of mixed powder, 3 to 10 parts by weight of reinforcing agent and 15 to 40 parts by weight of conditioning agent solution. The mixed powder is composed of 35-55 parts by weight of elemental silicon powder, 5-10 parts by weight of silicon nitride powder, and 5-20 parts by weight of silicon carbide powder. The reinforcing agent powder comprises 1 to 3 parts by weight of titanium nitride powder, 1 to 2 parts by weight of titanium carbide powder, and 1 to 5 parts by weight of titanium-silicon alloy.

2. The silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting according to claim 1, characterized in that, The purity of the elemental silicon powder is ≥99wt%, and the particle size is 200-600 mesh; the purity of the silicon nitride powder is ≥99wt%, and the particle size is 600-1000 mesh; the purity of the silicon carbide powder is ≥99wt%, and the particle size is 600-1000 mesh.

3. The silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 1, characterized in that, The purity of the reinforcing agent powder is ≥98wt%, and the particle size is 200-400 mesh.

4. The silicon nitride-bonded silicon carbide ceramic tube for aluminum alloy die casting according to claim 1, characterized in that, The mass ratio of water, surfactant, and HPMC in the conditioning solution is 1:0.02-0.05:0.15-0.

25.

5. A method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting, characterized in that, Includes the following steps: S1. The mixed powder and reinforcing agent powder described in claim 1 are mixed under argon or nitrogen protection for 12 hours for later use. The mixed powder is then placed in anhydrous ethanol and high-speed ball milling beads and ground in a high-speed ball mill under atmosphere protection for 1 to 4 hours. Then, reinforcing agent powder is added and grinding is continued for 2 to 8 hours to obtain a slurry. S2. The slurry obtained in step S1 is dried at 60-150°C using a spray granulation device to obtain a uniform and stable powder. 25-35 wt% of the conditioning agent solution described in claim 1 is added to the powder, and the mixture is kneaded in a kneader for 0.5-6 hours to obtain mud. S3. The clay obtained in step S2 is made into a ceramic tube blank and dried under constant temperature and humidity conditions. S4. Place the ceramic tube blank obtained in step S3 in a debinding furnace and heat it to 600-1050℃ at a heating rate of 1-5℃ / min. Hold it at this temperature for 0.5-3h to obtain a silicon nitride bonded silicon carbide ceramic tube blank. S5. Place the ceramic tube blank obtained in step S4 in a high-temperature sintering furnace. Under a nitrogen atmosphere, heat the material to 1050℃ at a heating rate of 5-15℃ / min and hold for 0.5-1h. Then heat the material to 1200℃ at a heating rate of 5-15℃ / min and hold for 1-3h. Next, heat the material to 1410-1450℃ at a heating rate of 5-15℃ / min and hold for 2-5h. Finally, heat the material to 1500-1650℃ at a heating rate of 5-10℃ / min and hold for 1-4h to obtain a novel silicon nitride-bonded silicon carbide ceramic tube.

6. The method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 5, characterized in that, In step S1, the rotation speed of the high-speed ball mill is 250 r / min to 350 r / min, the ball milling time is 6 to 9 h, the mass ratio of the mixed powder to anhydrous ethanol and high-speed ball milling beads is 1:4 to 8:2 to 3, the high-speed ball milling beads are one or more of agate ball milling beads, stainless steel ball milling beads and corundum ball milling beads, and the protective atmosphere is vacuum, argon, nitrogen or a combination of these atmospheres.

7. The method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 5, characterized in that, In step S2, the slurry is dried using a spray granulation device at 80–110°C.

8. The method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 5, characterized in that, In step S3, the clay is placed in a clay refining machine to obtain homogeneous clay, which is then placed in an extrusion molding machine to obtain a ceramic tube blank.

9. The method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 8, characterized in that, In step S3, the ceramic tube blank obtained by extrusion molding is subjected to isostatic pressing, with an isostatic pressing pressure of 150-200 MPa.

10. The method for preparing a silicon nitride-bonded silicon carbide ceramic feed tube for aluminum alloy die casting according to claim 5, characterized in that, In step S4, when the ceramic blank is sintered in the debinding furnace, the atmosphere is one or more of vacuum, argon, and nitrogen.