Methods to improve the interfacial reaction between ceramic shells and nickel-based superalloys

Abstract

This invention discloses a method for improving the interfacial reaction between a ceramic shell and a nickel-based superalloy. The method includes the following steps: sequentially applying a surface coating of slurry, applying a surface coating of sand, and drying the surface layer to a wax mold assembly; sequentially applying a back coating of slurry, applying a back coating of sand, and drying the back layer to the wax mold assembly; sequentially applying a sealing layer of slurry and drying the sealing layer to the wax mold assembly; dewaxing and firing the wax mold assembly to obtain a ceramic shell; and immersing the ceramic shell in yttrium oxide sol for three vacuum heating immersion treatments to form an inert yttrium oxide interfacial layer on the surface of the ceramic shell. This invention can form a continuous inert yttrium oxide reaction interface on the surface of the ceramic shell, thereby hindering the interfacial reaction between highly reactive elements in the alloy and the surface material of the ceramic shell, avoiding or mitigating sand adhesion problems, and improving the surface quality of turbine blades.

Description

Technical Field

[0001] This invention belongs to the field of precision casting technology for turbine blades, and specifically relates to a method for improving the interfacial reaction between ceramic shells and nickel-based superalloys. Background Technology

[0002] As is well known, turbine blades are the components with the highest temperature resistance in the entire aero-engine, and their service environment is extremely harsh. Currently, the average melting point of turbine blades is around 1300℃, but they must operate stably for a long time in an environment much higher than their own melting point. The temperature resistance of turbine blades directly determines the temperature of the turbine inlet, thus affecting the power limit of the aero-engine. This is why turbine blades are the most important core component in the entire aero-engine.

[0003] Currently, the main method for manufacturing turbine blades worldwide is precision casting, which requires multiple processes including wax pattern preparation, shell preparation, melting and casting. The shell preparation process includes the following steps: First, a ceramic slurry composed of refractory powder, binder, and organic additives is evenly coated onto the surface of the wax pattern. Then, refractory sand is applied and allowed to dry completely. This process of coating the slurry, applying sand, and drying is repeated to obtain a ceramic shell composed of layers of refractory slurry and refractory sand.

[0004] The surface layer of the ceramic mold shell, i.e., the first layer of ceramic slurry, comes into direct contact with the molten alloy. The melting process typically occurs at temperatures above 1400℃. At these high temperatures, the chemical reactions between the materials are extremely vigorous. The interfacial reactions between the ceramic mold shell's surface layer and the molten alloy exacerbate defects such as sand adhesion, ultimately damaging the surface quality of the casting. When castings undergo grinding, severe sand adhesion often requires deep grinding to remove it completely. However, for thin-walled castings with small dimensional tolerances, deep grinding can cause the actual dimensions of the turbine blades at the ground area to fall below the lower limit of the tolerance, rendering the turbine blades unusable. Therefore, there is an urgent need to develop a method to improve the interfacial reaction between the ceramic mold shell and the nickel-based superalloy, effectively reducing the probability of turbine blade failure due to grinding, while also reducing the labor costs of manual grinding.

[0005] Chinese patent application CN106311980A discloses a method for preparing a ceramic mold shell for casting high-temperature alloy directional / single-crystal blades. This method includes the following steps: preparing a surface layer slurry containing alumina powder, silica sol, and oxide powder (yttrium oxide, chromium oxide, molybdenum oxide, tungsten oxide, or any one or more of these); preparing a reinforcing layer slurry containing alumina powder and silica sol; applying the surface layer, reinforcing layer, sandblasting, and drying to a wax mold; and finally, after dewaxing and firing, obtaining a ceramic mold shell that prevents sand adhesion. This technical solution uses the surface coating to pre-absorb a certain amount of metal oxides to prevent the reaction between low-valence oxides and chromium in the alloy, reducing the transfer of chromium from the alloy into the mold shell, thereby eliminating the tendency for chemical sand adhesion. In other words, this technical solution only reduces sand adhesion in the ceramic mold shell through the surface material itself (limited material ratio and process parameters), without forming an additional interface layer. Therefore, the sand adhesion phenomenon still needs improvement. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides a method for improving the interfacial reaction between ceramic shells and nickel-based superalloys, the method comprising the following steps in sequence:

[0007] Step 1: According to the designed turbine blade structure, press the turbine blade wax model using hot press injection molding, and assemble several turbine blade wax models into a wax model module;

[0008] Step 2: Apply slurry, apply sand, and dry the wax model assembly sequentially to form the surface layer of the ceramic shell;

[0009] Step 3: After the surface coating is completed, the wax model assembly is coated with slurry, sand is poured onto the back layer, and the back layer is dried in sequence to form the back layer of the ceramic shell.

[0010] Step 4: After the back coating is completed, apply the sealing slurry to the wax model assembly in sequence, and let the sealing slurry dry to form the sealing layer of the ceramic shell;

[0011] Step 5: After the sealing layer is applied, place the wax mold assembly into the dewaxing kettle for dewaxing.

[0012] Step Six: After the dewaxing process is completed, the wax mold assembly is placed in a firing furnace for firing. After the firing process is completed, a ceramic shell will be obtained.

[0013] Step 7: Immerse the ceramic shell in yttrium oxide sol for three vacuum heating and soaking treatments. After the three vacuum heating and soaking treatments are completed, an inert yttrium oxide interface layer will be formed on the surface of the ceramic shell. This interface layer can improve the interfacial reaction between the ceramic shell and the nickel-based superalloy.

[0014] Preferably, in step two, the surface coating slurry is a surface ceramic slurry, wherein the mass percentage of each substance in the surface ceramic slurry is as follows: zirconium acetate binder 17-25 wt%, zirconium oxide powder 20-26 wt%, white corundum powder 50-60 wt%, first defoamer 0.2-0.8 wt%, first wetting agent 0.2-0.8 wt%, and the sum of the contents of each substance is 100 wt%.

[0015] The zirconium acetate binder contains 20-30 wt% ZrO2; the first defoamer contains 45-55 wt% organosilane defoamer and 45-55 wt% n-octanol; the first wetting agent is a geminitrosiloxane wetting agent; the median particle size of the white corundum powder is 20-30 μm, and the median particle size of the zirconium oxide powder is 15-25 μm.

[0016] The preparation method of the surface ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a first defoamer; then, zirconium acetate binder, the first defoamer, and the first wetting agent are placed in a reaction vessel and stirred at a temperature of 20-25℃ for 10-30 minutes to ensure complete fusion of the three substances; finally, zirconium oxide powder and white corundum powder are placed in the reaction vessel and stirred at a temperature of 20-25℃ for 1-5 hours to obtain the surface ceramic slurry; the viscosity of the surface ceramic slurry in the outflow cup is 10-30s.

[0017] The surface coating is made of corundum sand with a particle size of 100 mesh.

[0018] In any of the above solutions, it is preferred that, in step two, the wax model assembly is sequentially coated with a surface layer of slurry, coated with a surface layer of sand, and dried, including the following steps in the following order:

[0019] Step (2-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the surface ceramic slurry along a direction perpendicular to the horizontal plane, and apply the slurry to the surface. The application temperature is room temperature and the application time is 20-40 seconds.

[0020] Step (2-2): After the surface layer of slurry is applied, remove the wax mold assembly from the surface ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds.

[0021] Steps (2-3): After the rotation and slurry control are completed, place the wax mold assembly at a 40-50 degree angle to the horizontal plane in the center of the sand spraying machine, and apply the surface layer of sand. The application temperature is room temperature, and the application time is 30-40 seconds. During the surface layer application of sand, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove the loose sand.

[0022] Steps (2-4): After the surface coating of sand is completed, place the wax mold assembly in the drying room and dry the surface layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 10-16 hours, thus completing the surface coating of the ceramic shell.

[0023] In any of the above schemes, it is preferred that, in step three, the slurry applied to the back layer is a back layer ceramic slurry, wherein the mass percentage of each substance in the back layer ceramic slurry is as follows: silica sol binder 20-28 wt%, silica powder 16-22 wt%, mullite powder 52-60 wt%, second defoamer 0.2-0.8 wt%, and second wetting agent 0.2-0.8 wt%, and the sum of the contents of each substance is 100 wt%.

[0024] The SiO2 content in the silica sol binder is 20-30 wt%; the mass percentage of each substance in the first defoamer is 45-55 wt% organosilane defoamer and 45-55 wt% n-octanol; the first wetting agent is a geminitrosiloxane wetting agent; the median particle size of the silica powder is 15-25 μm, and the median particle size of the mullite powder is 20-30 μm.

[0025] The preparation method of the back layer ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a first defoamer; then, silica sol binder, a second defoamer, and a second wetting agent are placed in a reaction vessel and stirred at a temperature of 20-25℃ for 10-30 minutes to ensure complete fusion of the three substances; finally, silica powder and mullite powder are placed in the reaction vessel and stirred at a temperature of 20-25℃ for 1-5 hours to obtain the back layer ceramic slurry; the effluent cup viscosity of the back layer ceramic slurry is 10-20s.

[0026] The backing material is corundum sand with a particle size of 16 mesh.

[0027] In any of the above schemes, it is preferred that, in step three, the wax model assembly is sequentially coated with a backing slurry, coated with a backing sand, and dried, including the following steps in the following order:

[0028] Step (3-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the slurry to the back layer. The coating temperature is room temperature and the coating time is 20-40 seconds.

[0029] Step (3-2): After the back layer slurry is applied, remove the wax mold assembly from the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds.

[0030] Step (3-3): After the rotation and grouting are completed, place the wax mold assembly at a 40-50 degree angle to the horizontal plane in the center of the sand spraying machine, and apply sand to the back layer. The application temperature is room temperature, and the application time is 30-40 seconds. During the application of sand to the back layer, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove any loose sand.

[0031] Steps (3-4): After the back layer of sand is applied, place the wax mold assembly in the drying room and dry the back layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 8-12 hours.

[0032] Step (3-5): Repeat steps (3-1) to (3-4) 1-6 times to complete the back coating of the ceramic shell.

[0033] In any of the above schemes, it is preferred that, in step four, the sealant applied to the sealing layer is a ceramic sealant, which is the same as the backing ceramic sealant; the wax mold assembly is sequentially subjected to the sealant application and drying processes, including the following steps in order:

[0034] Step (4-1): Use a robotic arm or related clamping equipment to hold the wax model assembly, immerse the wax model assembly in the sealing layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the sealing layer slurry. The application temperature is room temperature, and the application time is 20-40 seconds. Step (4-2): After the sealing layer slurry is applied, remove the wax model assembly from the sealing layer ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds.

[0035] Step (4-3): After the rotation and control of the slurry is completed, place the wax mold assembly in the drying room and dry the slurry layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 8-12 hours, thus completing the slurry layer coating of the ceramic shell.

[0036] In any of the above schemes, it is preferred that, in step five, the dewaxing temperature of the wax model module is 160-190℃ and the dewaxing time is 0.5-1h.

[0037] In any of the above schemes, it is preferred that, in step six, the wax mold assembly is fired at a temperature of 700-1000℃ for 12-14 hours and then cooled to room temperature in the furnace.

[0038] In any of the above embodiments, it is preferred that, in step seven, the ceramic shell is immersed in yttrium oxide sol for three vacuum heating immersion treatments, including the following steps in sequence:

[0039] Step (7-1): Place the ceramic shell into a vacuum impregnation vessel while simultaneously injecting yttrium oxide sol into the vessel, ensuring the ceramic shell is completely submerged. First, evacuate the vessel to a vacuum level of 0.1-0.2 MPa, then heat it to a temperature of 35-45°C. Immerse the ceramic shell at this vacuum level and temperature for 25-35 minutes. Remove the ceramic shell from the vacuum impregnation vessel and allow it to stand at room temperature for 30-60 minutes. This completes the first vacuum heating and immersion treatment.

[0040] Step (7-2): Place the ceramic shell back into the vacuum impregnation vessel, and simultaneously add an appropriate amount of yttrium oxide sol to the vessel to completely immerse the ceramic shell in the yttrium oxide sol; first, evacuate to a vacuum degree of 0.1-0.2 MPa, then heat to a temperature of 50-60℃, and soak the ceramic shell at this vacuum degree and temperature for 1-1.5 hours; remove the ceramic shell from the vacuum impregnation vessel and place it directly into a drying oven at 190-210℃ for drying for 1-2 hours, then allow it to cool naturally to room temperature, thus completing the second vacuum heating and soaking treatment;

[0041] Step (7-3): Place the ceramic shell back into the vacuum impregnation vessel, and simultaneously add an appropriate amount of yttrium oxide sol to the vessel to completely immerse the ceramic shell in the yttrium oxide sol; first, evacuate to a vacuum degree of 0.1-0.2 MPa, then heat to a temperature of 70-80℃, and soak the ceramic shell at this vacuum degree and temperature for 2-2.5 hours; remove the ceramic shell from the vacuum impregnation vessel and place it directly into a drying oven at 400-450℃ for drying for 4-5 hours, then allow it to cool naturally to room temperature, thus completing the third vacuum heating and impregnation treatment.

[0042] In any of the above schemes, it is preferred that after the three vacuum heating immersion treatments are completed, an interface layer is formed on the surface of the ceramic shell, and the thickness of the interface layer is 1-10 μm.

[0043] In this invention, the viscosity of the surface ceramic slurry at the outlet cup is limited to 10-30s. If the viscosity is too high, the slurry fluidity will decrease, and material accumulation will occur in the mold shell, affecting the surface quality. If the viscosity is too low, the coating amount will be small, the surface slurry layer thickness will be too low, and the sand will easily penetrate the slurry layer, causing surface damage during casting and resulting in inclusions and scrap. Similarly, the viscosity of the back ceramic slurry at the outlet cup is limited to 10-20s. If the viscosity is too high, the coating amount will increase, and the overall shell thickness and weight will increase significantly. If the viscosity is too low, the coating amount will decrease, and the overall shell thickness and weight will decrease significantly.

[0044] In this invention, the impregnation solution used in the vacuum heating immersion treatment is yttrium oxide sol, whose main component is solid yttrium oxide. It possesses properties such as adhesiveness, thixotropy, easy dispersibility, water solubility and reversibility, suspension, adsorption, and stability. During vacuum heating, the yttrium oxide sol micro-gelles on the surface of the ceramic mold, forming an extremely thin yttrium oxide gel film. After drying, this gel film loses all its internal moisture, and the solid yttrium oxide directly adheres to the surface of the ceramic mold, forming an interface layer similar to a yttrium oxide coating. During the melting and casting process, this interface layer effectively prevents the reactive elements in the highly reactive alloy from reacting with the surface material of the ceramic mold, thereby reducing sand adhesion and improving the surface quality of the turbine blades.

[0045] In this invention, the ceramic shell undergoes three vacuum heating and immersion treatments, with the heating temperature and immersion time gradually increasing, resulting in the gradual formation of an interface layer. After the first vacuum heating and immersion treatment, a complete interface layer cannot yet be formed on the surface of the surface layer; after the second vacuum heating and immersion treatment, a complete interface layer gradually forms on the surface of the surface layer; after the third vacuum heating and immersion treatment, a protective layer is formed on the entire surface of the surface layer. The yttrium oxide sol is an aqueous solution, and its evaporation rate increases with increasing drying temperature, leading to increased adhesion of yttrium oxide to the ceramic shell and a gradual increase in the thickness of the formed protective layer.

[0046] Furthermore, the technical solution of this invention is specifically designed to improve the interfacial reaction between the ceramic shell and the nickel-based superalloy, which is completely different from the interfacial reaction between the ceramic core and the superalloy. Improving the interfacial reaction between the ceramic shell (i.e., the surface ceramic slurry of the ceramic shell) and the superalloy reduces the interfacial reaction on the outer surface of the turbine blade; improving the interfacial reaction between the ceramic core (i.e., the material used to prepare the ceramic core) and the superalloy reduces the interfacial reaction inside the turbine blade. The materials, processes, and reaction mechanisms of the ceramic shell and the ceramic core are completely different. Vacuum immersion treatment is a common step in the preparation of ceramic cores. In the field of improving the interfacial reaction between the ceramic shell and the superalloy, this invention proposes a multi-stage vacuum heating immersion treatment technique, where each vacuum heating immersion treatment requires different immersion temperatures, immersion times, drying temperatures, and drying times.

[0047] In this invention, during the process of improving the interfacial reaction between the ceramic shell and the nickel-based superalloy, the ceramic shell needs to undergo three vacuum heating and soaking treatments. The process parameters for each vacuum heating and soaking are very important. At the same time, the material ratio and preparation parameters of the surface ceramic slurry and the back ceramic slurry are also very important. All parameters need to work together to achieve the technical effect expected by this invention.

[0048] In this invention, the mixing equipment, robotic arms, clamping equipment, slurry dipping equipment, sand spraying machine, drying oven, vacuum impregnation kettle, dewaxing kettle, and calcining furnace used are all traditional equipment, with no special requirements on equipment structure or model. The hot-press casting method for turbine blade wax molds is a traditional process, with no special requirements on process flow, process parameters, pressing materials, or pressing equipment. After three vacuum heating and soaking treatments, the ceramic shell can be directly used for subsequent casting processes, with no special requirements on casting flow or casting parameters.

[0049] The method of the present invention for improving the interfacial reaction between ceramic shells and nickel-based superalloys has the following beneficial effects:

[0050] (1) The present invention employs a three-stage yttrium oxide sol vacuum heating immersion process to form a continuous inert reaction interface of yttrium oxide on the surface of the ceramic shell, thereby preventing the interfacial reaction between the highly reactive elements in the alloy and the surface material of the ceramic shell, avoiding or reducing the problem of sand adhesion, and improving the surface quality of the turbine blade.

[0051] (2) The method of the present invention can significantly improve the severe interfacial reaction phenomenon that occurs when the traditional silica sol ceramic shell layer is cast with high reactive alloy, and the method effectively reduces the processing difficulty and labor cost of precision castings during surface grinding.

[0052] (3) In the process of three vacuum heating and soaking treatments, the surface quality of the casting gradually improves as the vacuum heating temperature and vacuum soaking time gradually increase. This indicates that the yttrium oxide sol forms a protective layer on the surface of the ceramic shell through vacuum heating and soaking, thereby reducing the interfacial reaction between the highly reactive alloy and the surface of the ceramic shell and avoiding or mitigating the sand adhesion defect. Attached Figure Description

[0053] Figure 1 This is a process flow diagram of a preferred embodiment of the method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to the present invention;

[0054] Figure 2 Photographs of the surface of the test plates prepared using the methods of the three embodiments (three vacuum heating immersion treatments);

[0055] Figure 3 A photograph of the surface of the test plate prepared using the method of Comparative Example 2 (subject to a single vacuum heating immersion treatment);

[0056] Figure 4 A photograph of the surface of the test plate prepared using the method of Comparative Example 3 (two vacuum heating immersion treatments);

[0057] Figure 5 Microscopic images of test plates prepared using the methods of the three embodiments (three vacuum heating immersion treatments). Detailed Implementation

[0058] To further understand the invention, the following detailed description of the invention will be provided in conjunction with specific embodiments.

[0059] Example 1:

[0060] like Figure 1 As shown, in a preferred embodiment of the method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to the present invention, the method includes the following steps in sequence:

[0061] Step 1: According to the designed turbine blade structure, press the turbine blade wax model using hot press injection molding, and assemble several turbine blade wax models into a wax model module;

[0062] Step 2: Apply slurry, apply sand, and dry the wax model assembly sequentially to form the surface layer of the ceramic shell;

[0063] Step 3: After the surface coating is completed, the wax model assembly is coated with slurry, sand is poured onto the back layer, and the back layer is dried in sequence to form the back layer of the ceramic shell.

[0064] Step 4: After the back coating is completed, apply the sealing slurry to the wax model assembly in sequence, and let the sealing slurry dry to form the sealing layer of the ceramic shell;

[0065] Step 5: After the sealing layer is applied, place the wax mold assembly into the dewaxing kettle for dewaxing.

[0066] Step Six: After the dewaxing process is completed, the wax mold assembly is placed in a firing furnace for firing. After the firing process is completed, a ceramic shell will be obtained.

[0067] Step 7: Immerse the ceramic shell in yttrium oxide sol for three vacuum heating and soaking treatments. After the three vacuum heating and soaking treatments are completed, an inert yttrium oxide interface layer will be formed on the surface of the ceramic shell. This interface layer can improve the interfacial reaction between the ceramic shell and the nickel-based superalloy.

[0068] In step two, the surface coating slurry is a surface ceramic slurry. The mass percentage of each substance in the surface ceramic slurry is as follows: zirconium acetate binder 21 wt%, zirconium oxide powder 23 wt%, white fused alumina powder 55 wt%, first defoamer 0.5 wt%, and first wetting agent 0.5 wt%. The zirconium acetate binder contains 25 wt% ZrO2. The mass percentage of each substance in the first defoamer is as follows: organosilane defoamer 50 wt%, n-octanol 50 wt%. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the white fused alumina powder is 25 μm, and the median particle size of the zirconium oxide powder is 20 μm.

[0069] The preparation method of the surface ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a first defoamer; then, zirconium acetate binder, the first defoamer, and the first wetting agent are placed in a reaction vessel and stirred at a temperature of 22°C for 20 minutes to ensure complete fusion of the three substances; finally, zirconium oxide powder and white corundum powder are placed in the reaction vessel and stirred at a temperature of 22°C for 3 hours to obtain the surface ceramic slurry; the outflow cup viscosity of the surface ceramic slurry is 20s.

[0070] The surface coating is made of corundum sand with a particle size of 100 mesh.

[0071] In step two, the wax model assembly is sequentially coated with a slurry, then coated with sand, and finally dried. The steps, in that order, are as follows:

[0072] Step (2-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the surface ceramic slurry along a direction perpendicular to the horizontal plane, and apply the slurry to the surface. The application temperature is room temperature and the application time is 30 seconds.

[0073] Step (2-2): After the surface layer of slurry is applied, remove the wax mold assembly from the surface ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 40 seconds.

[0074] Steps (2-3): After the rotation and grouting are completed, place the wax mold assembly at a 45-degree angle to the horizontal plane in the center of the sand spraying machine, and apply the surface layer of sand. The application temperature is room temperature, and the application time is 35 seconds. During the surface layer application of sand, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove any loose sand.

[0075] Steps (2-4): After the surface coating of sand is completed, place the wax mold assembly in the drying room and dry the surface layer. The drying temperature is 30℃, the drying humidity is 65%, and the drying time is 13 hours, thus completing the surface coating of the ceramic shell.

[0076] In step three, the back coating slurry is a back ceramic slurry. The mass percentage of each substance in the back ceramic slurry is as follows: silica sol binder 24 wt%, silica powder 19 wt%, mullite powder 56 wt%, second defoamer 0.5 wt%, and second wetting agent 0.5 wt%. The silica sol binder contains 25 wt% SiO2. The mass percentage of each substance in the first defoamer is as follows: organosilane defoamer 50 wt% and n-octanol 50 wt%. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the silica powder is 20 μm, and the median particle size of the mullite powder is 25 μm.

[0077] The preparation method of the back layer ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a first defoamer; then, silica sol binder, a second defoamer, and a second wetting agent are placed in a reaction vessel and stirred at a temperature of 22°C for 20 minutes to ensure complete fusion of the three substances; finally, silica powder and mullite powder are placed in the reaction vessel and stirred at a temperature of 22°C for 3 hours to obtain the back layer ceramic slurry; the effluent cup viscosity of the back layer ceramic slurry is 15s.

[0078] The backing material is corundum sand with a particle size of 16 mesh.

[0079] In step three, the wax model assembly is sequentially coated with slurry, coated with sand, and dried, including the following steps in the following order:

[0080] Step (3-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the slurry to the back layer. The coating temperature is room temperature and the coating time is 30 seconds.

[0081] Step (3-2): After the back layer slurry is applied, remove the wax mold assembly from the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 40 seconds.

[0082] Step (3-3): After the rotation and grouting are completed, place the wax mold assembly at a 45-degree angle to the horizontal plane in the center of the sand spraying machine, and apply sand to the back layer. The application temperature is room temperature, and the application time is 35 seconds. During the application of sand to the back layer, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove any loose sand.

[0083] Steps (3-4): After the back layer of sand is applied, place the wax mold assembly in the drying room and dry the back layer. The drying temperature is 30℃, the drying humidity is 65%, and the drying time is 10 hours.

[0084] Step (3-5): Repeat steps (3-1) to (3-4) 6 times to complete the back coating of the ceramic shell.

[0085] In step four, the sealant applied to the wax mold assembly is a ceramic sealant, which is the same as the backing ceramic sealant. The wax mold assembly is then subjected to the following steps in sequence:

[0086] Step (4-1): Use a robotic arm or related clamping equipment to hold the wax model assembly, immerse the wax model assembly in the sealing layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the sealing layer slurry. The application temperature is room temperature, and the application time is 30 seconds. Step (4-2): After the sealing layer slurry is applied, remove the wax model assembly from the sealing layer ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 40 seconds.

[0087] Step (4-3): After the rotation and control of the slurry is completed, place the wax mold assembly in the drying room and dry the slurry layer. The drying temperature is 30℃, the drying humidity is 65%, and the drying time is 10 hours, thus completing the slurry layer coating of the ceramic shell.

[0088] In step five, the dewaxing temperature of the wax model module is 175℃ and the dewaxing time is 0.8h.

[0089] In step six, the wax mold assembly is fired at 850℃ for 13 hours and then cooled to room temperature in the furnace.

[0090] In step seven, the ceramic shell is immersed in yttrium oxide sol for three vacuum heating immersion treatments, including the following steps in sequence:

[0091] Step (7-1): Place the ceramic shell into a vacuum impregnation vessel and simultaneously inject yttrium oxide sol into the vessel, ensuring the ceramic shell is completely submerged. First, evacuate the vessel to a vacuum level of 0.15 MPa, then heat it to 40°C. Immerse the ceramic shell at this vacuum level and temperature for 30 minutes. Remove the ceramic shell from the vacuum impregnation vessel and allow it to stand at room temperature for 45 minutes. This completes the first vacuum heating and immersion treatment.

[0092] Step (7-2): Place the ceramic shell back into the vacuum impregnation vessel, and simultaneously add an appropriate amount of yttrium oxide sol to the vessel to completely immerse the ceramic shell in the yttrium oxide sol; first, evacuate to a vacuum degree of 0.15 MPa, then heat to a temperature of 55°C, and soak the ceramic shell at this vacuum degree and temperature for 1.2 hours; remove the ceramic shell from the vacuum impregnation vessel and place it directly into a drying oven at 200°C for 1.5 hours, then allow it to cool naturally to room temperature, thus completing the second vacuum heating and soaking treatment; Step (7-3): Place the ceramic shell back into the vacuum impregnation vessel, simultaneously adding an appropriate amount of yttrium oxide sol to ensure the ceramic shell is completely submerged. First, evacuate to a vacuum level of 0.15 MPa, then heat to 75°C, and soak the ceramic shell at this vacuum level and temperature for 2.2 hours. Remove the ceramic shell from the vacuum impregnation vessel and place it directly into a drying oven at 425°C for 4.5 hours. Allow it to cool naturally to room temperature, thus completing the third vacuum heating and impregnation treatment. After three vacuum heating and impregnation treatments, an interface layer with a thickness of 8 μm is formed on the surface of the ceramic shell.

[0093] The method for improving the interface reaction between the ceramic shell and the nickel-based superalloy in this embodiment has the following beneficial effects: (1) By using a three-stage yttrium oxide sol vacuum heating and immersion treatment process, a continuous inert yttrium oxide reaction interface is formed on the surface of the ceramic shell, thereby hindering the interface reaction between the highly reactive elements in the alloy and the surface material of the ceramic shell, reducing the sand adhesion problem, and improving the surface quality of the turbine blades. (2) It can significantly improve the severe interface reaction phenomenon that occurs when the surface layer of the traditional silica sol ceramic shell is cast with highly reactive alloys, and the method effectively reduces the processing difficulty and labor cost of precision castings during surface grinding.

[0094] Example 2:

[0095] Another preferred embodiment of the method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to the present invention has the same process flow, material ratio, technical principle, and beneficial effects as Embodiment 1, except that:

[0096] In step two, the surface coating slurry is a surface ceramic slurry. The mass percentages of each substance in the surface ceramic slurry are as follows: 25 wt% zirconium acetate binder, 22 wt% zirconium oxide powder, 52 wt% white fused alumina powder, 0.2 wt% first defoamer, and 0.8 wt% first wetting agent. The zirconium acetate binder contains 20 wt% ZrO2. The mass percentages of each substance in the first defoamer are as follows: 45 wt% organosilane defoamer and 55 wt% n-octanol. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the white fused alumina powder is 20 μm, and the median particle size of the zirconium oxide powder is 15 μm.

[0097] The main preparation parameters of the surface ceramic slurry are as follows: zirconium acetate binder, first defoamer, and first wetting agent are placed in a reaction vessel and stirred at a temperature of 25°C for 10 minutes; zirconium oxide powder and white corundum powder are placed in the reaction vessel and stirred at a temperature of 25°C for 1 hour; the viscosity of the surface ceramic slurry in the outflow cup is 10s.

[0098] The wax model assembly is subjected to a series of processes, including coating the surface with slurry, applying a layer of sand, and drying the surface. The main process parameters are as follows: when coating the surface with slurry, the coating temperature is room temperature and the coating time is 20 seconds; when rotating to control the slurry, the control temperature is room temperature and the control time is 30 seconds; when applying the sand, the wax model assembly is at a 40-degree angle to the horizontal plane, the sand application temperature is room temperature, and the sand application time is 30 seconds; when drying the surface, the drying temperature is 25℃, the drying humidity is 60%, and the drying time is 10 hours.

[0099] In step three, the back coating slurry is a back ceramic slurry. The mass percentage of each substance in the back ceramic slurry is as follows: silica sol binder 28 wt%, silica powder 17 wt%, mullite powder 54 wt%, second defoamer 0.2 wt%, and second wetting agent 0.8 wt%. The silica sol binder contains 20 wt% SiO2. The mass percentage of each substance in the first defoamer is as follows: organosilane defoamer 45 wt% and n-octanol 55 wt%. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the silica powder is 15 μm, and the median particle size of the mullite powder is 20 μm.

[0100] The main preparation parameters of the back layer ceramic slurry are as follows: silica sol binder, second defoamer, and second wetting agent are placed in a reactor and stirred at a temperature of 25°C for 10 minutes; silica powder and mullite powder are placed in the reactor and stirred at a temperature of 25°C for 1 hour; the viscosity of the back layer ceramic slurry in the outflow cup is 10s.

[0101] The wax model assembly was subjected to a series of processes, including applying a backing slurry, applying a backing sand coating, and drying the backing layer. The main process parameters included: when applying the slurry, the application temperature was room temperature and the application time was 20 seconds; when rotating and controlling the slurry, the control temperature was room temperature and the control time was 30 seconds; when applying the backing sand coating, the wax model assembly was at a 40-degree angle to the horizontal plane, the coating temperature was room temperature, and the coating time was 30 seconds; when drying the backing layer, the drying temperature was 25℃, the drying humidity was 60%, and the drying time was 8 hours; a total of 7 backing layer structures were applied.

[0102] In step four, the slurry applied to the sealing layer is a ceramic slurry, which is the same as the ceramic slurry used for the back layer. The wax mold assembly is then subjected to the following processes: application of the sealing slurry and drying of the sealing layer. The main process parameters include: during application, the temperature is room temperature and the application time is 20 seconds; during rotational slurry control, the temperature is room temperature and the control time is 30 seconds; during drying, the temperature is 25°C, the humidity is 60%, and the drying time is 8 hours.

[0103] In step five, the dewaxing temperature of the wax model module is 160℃ and the dewaxing time is 1 hour.

[0104] In step six, the wax mold assembly is fired at 700℃ for 14 hours and then cooled to room temperature in the furnace.

[0105] In step seven, the ceramic shell is immersed in yttrium oxide sol for three vacuum heating and soaking treatments. The main process parameters include: in the first vacuum heating and soaking treatment, the vacuum level is reduced to 0.1 MPa, the temperature is increased to 35°C, and the ceramic shell is immersed for 25 minutes at this vacuum level and temperature, followed by standing at room temperature for 30 minutes; in the second vacuum heating and soaking treatment, the vacuum level is reduced to 0.1 MPa, the temperature is increased to 50°C, and the ceramic shell is immersed for 1 hour at this vacuum level and temperature, followed by drying at 190°C for 2 hours; in the third vacuum heating and soaking treatment, the vacuum level is reduced to 0.1 MPa, the temperature is increased to 70°C, and the ceramic shell is immersed for 2 hours at this vacuum level and temperature, followed by drying at 400°C for 5 hours. After the three vacuum heating and soaking treatments, an interface layer with a thickness of 10 μm is formed on the surface of the ceramic shell.

[0106] Example 3:

[0107] Another preferred embodiment of the method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to the present invention has the same process flow, material ratio, technical principle, and beneficial effects as Embodiment 1, except that:

[0108] In step two, the surface coating slurry is a surface ceramic slurry. The mass percentages of each substance in the surface ceramic slurry are as follows: zirconium acetate binder 17 wt%, zirconium oxide powder 25 wt%, white fused alumina powder 57 wt%, first defoamer 0.8 wt%, and first wetting agent 0.2 wt%. The zirconium acetate binder contains 30 wt% ZrO2. The mass percentages of each substance in the first defoamer are as follows: organosilane defoamer 55 wt% and n-octanol 45 wt%. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the white fused alumina powder is 30 μm, and the median particle size of the zirconium oxide powder is 25 μm.

[0109] The main preparation parameters of the surface ceramic slurry are as follows: zirconium acetate binder, first defoamer, and first wetting agent are placed in a reaction vessel and stirred at a temperature of 20°C for 30 minutes; zirconium oxide powder and white corundum powder are placed in the reaction vessel and stirred at a temperature of 20°C for 5 hours; the viscosity of the surface ceramic slurry in the outflow cup is 30s.

[0110] The wax model assembly is subjected to a series of processes, including coating the surface with slurry, applying a layer of sand, and drying the surface. The main process parameters are as follows: when coating the surface with slurry, the coating temperature is room temperature and the coating time is 40 seconds; when rotating to control the slurry, the control temperature is room temperature and the control time is 50 seconds; when applying the sand, the wax model assembly is at a 50-degree angle to the horizontal plane, the sand application temperature is room temperature, and the sand application time is 40 seconds; when drying the surface, the drying temperature is 35℃, the drying humidity is 70%, and the drying time is 16 hours.

[0111] In step three, the back coating slurry is a back ceramic slurry. The mass percentage of each substance in the back ceramic slurry is as follows: silica sol binder 20 wt%, silica powder 21 wt%, mullite powder 58 wt%, second defoamer 0.8 wt%, and second wetting agent 0.2 wt%. The silica sol binder contains 30 wt% SiO2. The mass percentage of each substance in the first defoamer is as follows: organosilane defoamer 55 wt% and n-octanol 45 wt%. The first wetting agent is a geminitrosiloxane wetting agent. The median particle size of the silica powder is 25 μm, and the median particle size of the mullite powder is 30 μm.

[0112] The main preparation parameters of the back layer ceramic slurry are as follows: silica sol binder, second defoamer, and second wetting agent are placed in a reactor and stirred at a temperature of 20°C for 30 minutes; silica powder and mullite powder are placed in the reactor and stirred at a temperature of 20°C for 5 hours; the viscosity of the back layer ceramic slurry in the outflow cup is 20s.

[0113] The wax model assembly was subjected to a series of processes, including applying a backing slurry, applying a backing sand coating, and drying the backing layer. The main process parameters included: when applying the slurry, the coating temperature was room temperature and the coating time was 40 seconds; when rotating and controlling the slurry, the control temperature was room temperature and the control time was 50 seconds; when applying the backing sand coating, the wax model assembly was at a 50-degree angle to the horizontal plane, the coating temperature was room temperature, and the coating time was 40 seconds; when drying the backing layer, the drying temperature was 35℃, the drying humidity was 70%, and the drying time was 12 hours; a total of 7 backing layer structures were applied.

[0114] In step four, the slurry applied to the sealing layer is a ceramic slurry, which is the same as the ceramic slurry used for the back layer. The wax mold assembly is then subjected to the following processes: application of the sealing slurry and drying of the sealing layer. The main process parameters include: during application, the temperature is room temperature and the application time is 40 seconds; during rotational slurry control, the temperature is room temperature and the control time is 50 seconds; during drying, the temperature is 35℃, the humidity is 70%, and the drying time is 12 hours.

[0115] In step five, the dewaxing temperature of the wax model module is 190℃ and the dewaxing time is 0.5h.

[0116] In step six, the wax model assembly is fired at a temperature of 1000℃ for 12 hours and then cooled to room temperature in the furnace.

[0117] In step seven, the ceramic shell is immersed in yttrium oxide sol for three vacuum heating and soaking treatments. The main process parameters include: in the first vacuum heating and soaking treatment, the vacuum degree is evacuated to 0.2 MPa, the temperature is heated to 45°C, and the ceramic shell is immersed for 35 minutes at this vacuum degree and temperature, followed by standing at room temperature for 60 minutes; in the second vacuum heating and soaking treatment, the vacuum degree is evacuated to 0.2 MPa, the temperature is heated to 60°C, and the ceramic shell is immersed for 1.5 hours at this vacuum degree and temperature, followed by drying at 210°C for 1 hour; in the third vacuum heating and soaking treatment, the vacuum degree is evacuated to 0.2 MPa, the temperature is heated to 80°C, and the ceramic shell is immersed for 2.5 hours at this vacuum degree and temperature, followed by drying at 450°C for 4 hours. After the three vacuum heating and soaking treatments, an interface layer with a thickness of 7 μm is formed on the surface of the ceramic shell.

[0118] Comparative Example 1:

[0119] In this comparative example, the ceramic shell was not subjected to a vacuum heating and soaking process after preparation. The preparation process of the ceramic shell and the process parameters of each step were basically the same as in Example 1.

[0120] Comparative Example 2:

[0121] In this comparative example, after the ceramic shell was prepared, it underwent a vacuum heating and immersion treatment process. The preparation process of the ceramic shell and the process parameters of each step were basically the same as in Example 1. The vacuum heating and immersion treatment process and process parameters were basically the same as the first vacuum heating and immersion treatment process in Example 1.

[0122] Comparative Example 3:

[0123] In this comparative example, after the ceramic shell was prepared, it underwent two vacuum heating and immersion treatment processes. The preparation process of the ceramic shell and the process parameters of each step were basically the same as those in Example 1. The two vacuum heating and immersion treatment processes and process parameters were basically the same as those in the first and second vacuum heating and immersion treatment processes in Example 1, respectively.

[0124] The ceramic shells of the three embodiments and three comparative examples were used for subsequent casting processes. The casting process, casting parameters, alloy liquid, etc. were all the same. The thickness of the sand layer on the surface of the castings was tested, as shown in Table 1.

[0125] Table 1 Test results of sand adhesion layer thickness on casting surface

[0126] Test Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Thickness of the sand-adhesive layer (μm) 3.51 3.07 3.93 52.5 31.96 20.44

[0127] The surface quality of the test plates prepared using the methods of the three embodiments (three vacuum heating immersion treatments) is as follows: Figure 2 As shown, the microscopic photographs are as follows Figure 5 As shown; the surface quality of the test plate prepared using the method of Comparative Example 2 (subject to one vacuum heating immersion treatment) is as follows. Figure 3 As shown; the surface quality of the test plate prepared using the method of Comparative Example 3 (two vacuum heating immersion treatments) is as follows. Figure 4 As shown.

[0128] From Table 1 and Figure 2-5 It can be seen that after the ceramic shells of the three embodiments were subjected to three vacuum heating and immersion treatments, the thickness of the sand adhering layer on the surface of the castings was very small, even negligible, and the surface quality of the castings was very good. This indicates that the yttrium oxide sol formed a good protective layer on the surface of the ceramic shell through three vacuum heating and immersion treatments, thereby reducing the interfacial reaction between the highly reactive alloy and the surface of the ceramic shell and avoiding sand adhering defects.

[0129] The yttrium oxide sol used in the above examples and comparative examples was purchased from Forsmann Technology (Beijing) Co., Ltd., the zirconium acetate binder was purchased from Zhongshan Dixin Chemical Co., Ltd., the silica sol (model FSI silica sol) was purchased from Zhejiang Yuda Chemical Co., Ltd., the organosilane defoamer was purchased from Shandong Dinghong New Materials Co., Ltd., the genomic siloxane wetting agent (model LW-4100) was purchased from Dongguan Good New Materials Co., Ltd., and other chemical reagents and powder materials were purchased from Aladdin Reagent Co., Ltd. and Sinopharm Chemical Reagent Co., Ltd.

[0130] Special Note: The technical solution of this invention involves numerous parameters, and the synergistic effects between these parameters must be comprehensively considered to achieve the beneficial effects and significant progress of this invention. Furthermore, the value ranges of each parameter in the technical solution were obtained through extensive experimentation. For each parameter and the combinations thereof, the inventors have recorded a large amount of experimental data; however, due to space limitations, the specific experimental data is not disclosed here.

[0131] Those skilled in the art will readily understand that the method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to the present invention includes any combination of the inventive description and specific embodiments described in the above specification and the various parts shown in the accompanying drawings. Due to space limitations and for the sake of brevity, not all of these combinations have been described in detail. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the interfacial reaction between a ceramic shell and a nickel-based superalloy, characterized in that: The method includes the following steps in sequence. Step 1: According to the designed turbine blade structure, press the turbine blade wax model using hot press injection molding, and assemble several turbine blade wax models into a wax model module; Step 2: Apply slurry, apply sand, and dry the wax model assembly sequentially to form the surface layer of the ceramic shell; Step 3: After the surface coating is completed, the wax model assembly is coated with slurry, sand is poured onto the back layer, and the back layer is dried in sequence to form the back layer of the ceramic shell. Step 4: After the back coating is completed, apply the sealing slurry to the wax model assembly in sequence, and let the sealing slurry dry to form the sealing layer of the ceramic shell; Step 5: After the sealing layer is applied, place the wax mold assembly into the dewaxing kettle for dewaxing. Step Six: After the dewaxing process is completed, the wax mold assembly is placed in a firing furnace for firing. After the firing process is completed, a ceramic shell will be obtained. Step 7: Immerse the ceramic shell in yttrium oxide sol for three vacuum heating and soaking treatments. After the three vacuum heating and soaking treatments are completed, an inert yttrium oxide interface layer will be formed on the surface of the ceramic shell. This interface layer can improve the interfacial reaction between the ceramic shell and the nickel-based superalloy. In step seven, the ceramic shell is immersed in yttrium oxide sol for three vacuum heating immersion treatments, including the following steps in sequence: Step (7-1): Place the ceramic shell into a vacuum impregnation vessel while simultaneously injecting yttrium oxide sol into the vessel, ensuring the ceramic shell is completely submerged. First, evacuate the vessel to a vacuum level of 0.1-0.2 MPa, then heat it to a temperature of 35-45°C. Immerse the ceramic shell at this vacuum level and temperature for 25-35 minutes. Remove the ceramic shell from the vacuum impregnation vessel and allow it to stand at room temperature for 30-60 minutes. This completes the first vacuum heating and immersion treatment. Step (7-2): Place the ceramic shell back into the vacuum impregnation vessel, and simultaneously add an appropriate amount of yttrium oxide sol to the vessel to completely immerse the ceramic shell in the yttrium oxide sol; first, evacuate to a vacuum degree of 0.1-0.2 MPa, then heat to a temperature of 50-60℃, and soak the ceramic shell at this vacuum degree and temperature for 1-1.5 hours; remove the ceramic shell from the vacuum impregnation vessel and place it directly into a drying oven at 190-210℃ for drying for 1-2 hours, then allow it to cool naturally to room temperature, thus completing the second vacuum heating and soaking treatment; Step (7-3): Place the ceramic shell back into the vacuum impregnation vessel, and simultaneously add an appropriate amount of yttrium oxide sol to the vessel to completely immerse the shell in the sol. First, evacuate to a vacuum level of 0.1-0.2 MPa, then heat to 70-80°C. Immerse the shell at this vacuum level and temperature for 2-2.5 hours. Remove the shell from the vessel and place it directly into a drying oven at 400-450°C for 4-5 hours. Allow it to cool naturally to room temperature, thus completing the third vacuum heating and impregnation treatment.

2. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 1, characterized in that: In step two, the surface coating slurry is a surface ceramic slurry. The mass percentage of each substance in the surface ceramic slurry is as follows: zirconium acetate binder 17-25 wt%, zirconium oxide powder 20-26 wt%, white corundum powder 50-60 wt%, first defoamer 0.2-0.8 wt%, and first wetting agent 0.2-0.8 wt%, with the sum of the contents of each substance being 100 wt%. The zirconium acetate binder contains 20-30 wt% ZrO2; the defoamer contains the following components at the following mass percentages: 45-55 wt% organosilane defoamer and 45-55 wt% n-octanol; the first wetting agent is a geminitrosiloxane wetting agent; the white corundum powder has a median particle size of 20-30 μm, and the zirconium oxide powder has a median particle size of 15-25 μm; The preparation method of the surface ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a first defoamer; then, zirconium acetate binder, the first defoamer, and the first wetting agent are placed in a reaction vessel and stirred at a temperature of 20-25°C for 10-30 minutes to ensure complete fusion of the three substances; finally, zirconium oxide powder and white corundum powder are placed in the reaction vessel and stirred at a temperature of 20-25°C for 1-5 hours to obtain the surface ceramic slurry; the viscosity of the surface ceramic slurry in the outflow cup is 10-30s. The surface coating is made of corundum sand with a particle size of 100 mesh.

3. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 2, characterized in that: In step two, the wax model assembly undergoes a series of processes: applying a surface coating of slurry, applying a surface coating of sand, and drying the surface. These processes, in sequence, include the following steps: Step (2-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the surface ceramic slurry along a direction perpendicular to the horizontal plane, and apply the slurry to the surface. The application temperature is room temperature and the application time is 20-40 seconds. Step (2-2): After the surface layer of slurry is applied, remove the wax mold assembly from the surface ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds. Steps (2-3): After the rotation and slurry control are completed, place the wax mold assembly at a 40-50 degree angle to the horizontal plane in the center of the sand spraying machine, and apply the surface layer of sand. The spraying temperature is room temperature, and the spraying time is 30-40 seconds. During the surface layer of sand spraying, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove the loose sand. Steps (2-4): After the surface coating of sand is completed, place the wax mold assembly in the drying room and dry the surface layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 10-16 hours, thus completing the surface coating of the ceramic shell.

4. The method for improving the interfacial reaction between the ceramic shell and the nickel-based superalloy according to claim 3, characterized in that: In step three, the back coating slurry is a back ceramic slurry. The mass percentage of each substance in the back ceramic slurry is as follows: silica sol binder 20-28 wt%, silica powder 16-22 wt%, mullite powder 52-60 wt%, second defoamer 0.2-0.8 wt%, and second wetting agent 0.2-0.8 wt%, with the sum of the contents of each substance being 100 wt%. The silica sol binder contains 20-30 wt% SiO2; the second defoamer contains the following components at the following mass percentages: 45-55 wt% organosilane defoamer and 45-55 wt% n-octanol; the second wetting agent is a gemini-siloxane wetting agent; the median particle size of the silica powder is 15-25 μm, and the median particle size of the mullite powder is 20-30 μm. The preparation method of the back layer ceramic slurry is as follows: First, organosilane defoamer and n-octanol are mixed evenly at room temperature to obtain a second defoamer; then, silica sol binder, the second defoamer, and the second wetting agent are placed in a reaction vessel and stirred at a temperature of 20-25°C for 10-30 minutes to ensure complete fusion of the three substances; finally, silica powder and mullite powder are placed in the reaction vessel and stirred again at a temperature of 20-25°C for 1-5 hours to obtain the back layer ceramic slurry; the effluent cup viscosity of the back layer ceramic slurry is 10-20s. The backing material is corundum sand with a particle size of 16 mesh.

5. The method for improving the interfacial reaction between the ceramic shell and the nickel-based superalloy according to claim 4, characterized in that: In step three, the wax model assembly undergoes the following steps in sequence: applying a backing slurry, applying a backing sand coating, and drying the backing layer. Step (3-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the slurry to the back layer. The coating temperature is room temperature and the coating time is 20-40 seconds. Step (3-2): After the back layer slurry is applied, remove the wax mold assembly from the back layer ceramic slurry in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds. Step (3-3): After the rotation and grouting are completed, place the wax mold assembly at a 40-50 degree angle to the horizontal plane in the center of the sand spraying machine, and apply sand to the back layer. The application temperature is room temperature, and the application time is 30-40 seconds. During the application of sand to the back layer, the wax mold assembly needs to be rotated at a uniform speed to ensure that all parts of the wax mold assembly are evenly coated with sand. Then, gently shake to remove any loose sand. Steps (3-4): After the back layer of sand is applied, place the wax mold assembly in the drying room and dry the back layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 8-12 hours. Step (3-5): Repeat steps (3-1) to (3-4) 1-6 times to complete the back coating of the ceramic shell.

6. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 5, characterized in that: In step four, the sealant applied to the wax mold assembly is a ceramic sealant, which is the same as the backing ceramic sealant. The wax mold assembly is then subjected to the following steps in sequence: applying the sealant and drying the sealant. Step (4-1): Use a robotic arm or related clamping equipment to clamp the wax model assembly, immerse the wax model assembly in the sealing layer ceramic slurry in a direction perpendicular to the horizontal plane, and apply the sealing layer slurry. The application temperature is room temperature and the application time is 20-40 seconds. Step (4-2): After the sealing layer is coated with slurry, remove the wax mold from the ceramic slurry of the sealing layer in a direction perpendicular to the horizontal plane, and rotate it to control the slurry. The slurry control temperature is room temperature, and the slurry control time is 30-50 seconds. Step (4-3): After the rotation and control of the slurry is completed, place the wax mold assembly in the drying room and dry the slurry layer. The drying temperature is 25-35℃, the drying humidity is 60-70%, and the drying time is 8-12 hours, thus completing the slurry layer coating of the ceramic shell.

7. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 6, characterized in that: In step five, the dewaxing temperature of the wax model module is 160-190℃ and the dewaxing time is 0.5-1h.

8. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 7, characterized in that: In step six, the wax mold assembly is fired at a temperature of 700-1000℃ for 12-14 hours and then cooled to room temperature in the furnace.

9. The method for improving the interfacial reaction between ceramic shells and nickel-based superalloys according to claim 8, characterized in that: After three vacuum heating and immersion treatments are completed, an interface layer is formed on the surface of the ceramic shell, with a thickness of 1-10 μm.

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