Preparation and removal method of ceramic core skeleton reinforced ceramic core
By setting an alumina-based ceramic core skeleton inside the silicon-based ceramic core, the problems of thermal deformation and fracture of the silicon-based ceramic core are solved, the yield of hollow metal castings is improved, and the removal process of the alumina-based ceramic core skeleton is simplified.
Patent Information
- Application Number
- CN202511637917.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-10
- Publication Date
- 2026-02-10
AI Technical Summary
Traditional silicon-based ceramic cores suffer from severe thermal deformation when used at high temperatures, making it difficult to meet the requirements of directional crystal and single crystal casting. Furthermore, large-sized ceramic cores are prone to breakage, and aluminum-based ceramic cores are difficult to remove, affecting the yield of hollow metal castings.
An alumina-based ceramic core skeleton is set inside a silicon-based ceramic core. By injecting silicon-based ceramic core slurry and removing the mold, a ceramic core skeleton-reinforced ceramic core is formed. The silicon-based ceramic core is removed first, followed by the alumina-based ceramic core skeleton. The alumina-based ceramic core skeleton is separated from the inner wall of the metal casting, which facilitates removal.
It significantly improves the high-temperature strength and deflection of silicon-based ceramic cores, reduces fracture problems, increases the yield of hollow metal castings, and shortens the removal cycle of alumina-based ceramic core skeleton cores.
Smart Images
Figure CN121492212A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of ceramic core preparation technology, specifically relating to a method for preparing and removing a ceramic core reinforced with a ceramic core skeleton. Background Technology
[0002] With the continuous increase in flame temperature at the inlet of aero-engines and gas turbines, higher requirements are being placed on the heat resistance of cast superalloys used in hot-end components such as blades. Cast superalloys have undergone a development process from equiaxed crystals to oriented crystals and then to single crystals. In addition to the development of cast superalloy materials, manufacturing aero-engine and gas turbine blades as hollow structures, and cooling the blade body through the flow of cooling gas within the blade's internal cooling channels, is also an effective means of improving the blade's heat resistance.
[0003] In investment casting, the ceramic core is the key to forming the complex internal cooling channels of hollow blades. During the casting and solidification of high-temperature molten metal, the ceramic core is subjected to high temperature and various complex stresses, as well as corrosion from the high-temperature molten metal.
[0004] Currently, widely used silicon-based ceramic cores typically have a temperature resistance between 1480℃ and 1520℃. However, with the use of directional and single-crystal cast high-temperature alloys in turbine blades, ceramic cores are required to operate at even higher temperatures. The casting temperature of some single-crystal turbine blades has already reached 1550℃, and traditional silicon-based ceramic cores exhibit significant thermal deformation at this temperature, failing to meet the requirements of directional solidification. Furthermore, with the development of gas turbines, large-sized gas turbine blades are increasingly being used in engineering applications. The ceramic cores used to form the internal cooling channels of these large-sized gas turbine blades also need to be correspondingly larger. This increased size leads to increased weight and greater expansion at high temperatures, resulting in more complex shapes. In such cases, traditional silicon-based ceramic cores may even fracture in thicker sections.
[0005] Alumina-based ceramic cores, also known as aluminum-based ceramic cores, have excellent high-temperature strength and flexibility, which can effectively solve the above problems. However, it is very difficult to remove pure alumina ceramic cores, especially for large blades. The size of aluminum-based ceramic cores used to form the internal cooling channels of large blades increases significantly, which ultimately makes it difficult to remove the aluminum-based ceramic cores. In fact, the blades may even crack during the removal process. Summary of the Invention
[0006] In view of the above-mentioned defects of the prior art, the present invention provides a method for preparing and removing ceramic cores with ceramic core skeleton reinforcement. This method is applicable to the preparation of ceramic cores used in investment casting of oriented crystal and single crystal hollow metal castings, and the alumina-based ceramic core skeleton core in the obtained ceramic core skeleton reinforcement ceramic core is easy to remove.
[0007] The technical solution adopted by this invention to solve its technical problem is:
[0008] A method for preparing and removing a ceramic core reinforced with a ceramic core skeleton includes the following steps:
[0009] S1. Prepare an alumina-based ceramic core framework, wherein the ceramic core framework is provided with a fixed end;
[0010] S2. Prepare a ceramic core mold, wherein the ceramic core mold is provided with a positioning groove that matches the fixed end;
[0011] S3. Place the ceramic core skeleton into the ceramic core mold and insert the fixed end into the positioning groove;
[0012] S4. First, inject silicon-based ceramic core slurry into the ceramic core mold that has the ceramic core skeleton fixed. Then, remove the ceramic core mold to obtain a ceramic core skeleton reinforced ceramic core green body. After sintering, trimming, strengthening and inspection, a ceramic core skeleton reinforced ceramic core composed of alumina-based ceramic core skeleton and silicon-based ceramic core is obtained. Remove the fixed end from the qualified ceramic core skeleton reinforced ceramic core.
[0013] S5. When preparing a hollow metal casting using a qualified ceramic core reinforced with a ceramic core skeleton, after directional solidification, a metal casting is formed that encapsulates the ceramic core skeleton reinforced with a ceramic core skeleton. Then, the silicon-based ceramic core in the ceramic core skeleton reinforced with a ceramic core skeleton is removed first, so that a certain gap is left between the alumina-based ceramic core skeleton and the inner wall of the metal casting, and then the alumina-based ceramic core skeleton is removed.
[0014] Furthermore, in step S1: if the part that needs to be reinforced in the subsequently obtained silicon-based ceramic core is a straight channel structure, then the ceramic core skeleton is a straight pure alumina rod or pure alumina plate, and the size of the ceramic core skeleton is 10%-90% of the size of the part that needs to be reinforced in the subsequent silicon-based ceramic core.
[0015] Further, in step S1: if there is a bent part in the position that needs to be reinforced in the subsequently obtained silicon-based ceramic core, a ceramic core skeleton mold is first made as needed, wherein the inner cavity size of the ceramic core skeleton mold is 10%-90% of the size of the part that needs to be reinforced in the subsequent silicon-based ceramic core. Then, alumina-based ceramic core skeleton slurry is injected into the ceramic core skeleton mold, and then the ceramic core skeleton mold is removed to obtain an alumina-based ceramic core skeleton green body as a ceramic core skeleton.
[0016] Furthermore, in step S3: after the ceramic core skeleton is fixed inside the ceramic core mold, the ceramic core skeleton is located at the middle position where the silicon-based ceramic core needs to be reinforced in the subsequently obtained ceramic core skeleton reinforced ceramic core.
[0017] Further, in step S4: the inspection specifically involves checking whether the obtained ceramic core skeleton reinforced ceramic core has cracked due to the presence of the alumina-based ceramic core skeleton; the fixed end of the qualified ceramic core skeleton reinforced ceramic core is removed, specifically by physically cutting off or grinding the fixed end of the qualified ceramic core skeleton reinforced ceramic core.
[0018] Furthermore, in step S5: the outer side of the formed metal casting is provided with a ceramic shell, and the ceramic shell is removed before removing the silicon-based ceramic core.
[0019] Further, in step S5: the silicon-based ceramic core in the ceramic core skeleton reinforced ceramic core is removed, specifically by using a 35wt%-45wt% KOH aqueous solution or NaOH aqueous solution under a pressure of 0.2MPa-0.4MPa and a temperature of 115℃-125℃ to remove the silicon-based ceramic core.
[0020] Furthermore, in step S5: if the part that needs to be reinforced in the obtained silicon-based ceramic core is a straight channel structure, then after removing the silicon-based ceramic core, the alumina-based ceramic core skeleton core slides out of the inner cavity of the metal casting to remove the alumina-based ceramic core skeleton core.
[0021] Further, in step S5: if there is a bent part in the position that needs to be reinforced in the obtained silicon-based ceramic core, after removing the silicon-based ceramic core, the alumina-based ceramic core skeleton core in the inner cavity of the metal casting is first broken by physical method, and then cleaned with water to remove the alumina-based ceramic core skeleton core.
[0022] Furthermore, in step S5: if there is a bent portion at the location requiring reinforcement in the obtained silicon-based ceramic core, then after removing the silicon-based ceramic core, an aluminum-based core removal alkali solution is used to remove the alumina-based ceramic core skeleton core.
[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0024] The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to the present invention includes the following steps: S1, preparing an alumina-based ceramic core framework, wherein the ceramic core framework is provided with a fixed end; S2, preparing a ceramic core mold, wherein the ceramic core mold is provided with a positioning groove adapted to the fixed end; S3, placing the ceramic core framework into the ceramic core mold and inserting the fixed end into the positioning groove; S4, first injecting silicon-based ceramic core slurry into the ceramic core mold with the ceramic core framework fixed, and then removing the ceramic core mold to obtain a ceramic core reinforced with a ceramic core framework green body, which is then sintered, trimmed, strengthened, and inspected. The test yields a ceramic core reinforced with a ceramic core skeleton composed of an alumina-based ceramic core skeleton and a silicon-based ceramic core. The fixed end of the qualified ceramic core skeleton reinforced with a ceramic core skeleton is removed. S5. When preparing a hollow metal casting using a qualified ceramic core skeleton reinforced with a ceramic core skeleton, after directional solidification, a metal casting is formed that encapsulates the ceramic core skeleton reinforced with a ceramic core skeleton. Then, the silicon-based ceramic core in the ceramic core skeleton reinforced with a ceramic core skeleton is removed first, so that a certain gap is left between the alumina-based ceramic core skeleton and the inner wall of the metal casting. Then, the alumina-based ceramic core skeleton is removed. This invention combines the advantages of both silicon-based ceramic cores and alumina-based ceramic cores by incorporating an alumina-based ceramic skeleton core within a conventional silicon-based ceramic core. This significantly improves the high-temperature strength and deflection of the silicon-based ceramic core and greatly reduces its fracture rate, thereby increasing the yield of the desired hollow metal castings. Furthermore, after directional solidification, the removal of the silicon-based ceramic core from the ceramic skeleton-reinforced ceramic core creates a certain gap between the alumina-based ceramic skeleton core and the inner wall of the metal casting. This facilitates the removal of alumina-based ceramic core skeletons, thereby significantly shortening the removal cycle. In summary, this method is suitable for the preparation of ceramic cores used in investment casting of oriented crystal and single crystal hollow metal castings such as blades. Furthermore, the alumina-based ceramic core skeleton in the obtained ceramic core skeleton-reinforced ceramic core is easy to remove, which can solve the problems of low temperature resistance and low strength of traditional silicon-based ceramic cores and the difficulty in removing aluminum-based ceramic cores used in investment casting of oriented crystal and single crystal hollow alloy blades in the background art. Attached Figure Description
[0025] Figure 1 This is a photograph of the easily fractured location in a traditional silicon-based ceramic core in Example 1;
[0026] Figure 2 This is a photograph of the ceramic core reinforced with a ceramic core skeleton in Example 1;
[0027] Figure 3This is a photograph of the easily fractured location in the traditional silicon-based ceramic core in Example 2;
[0028] Figure 4 This is a photograph of the actual location where the irregularly shaped alumina-based ceramic core skeleton is embedded in the ceramic core skeleton reinforced ceramic core in Example 2.
[0029] The following are the labels in the figure: 1. Silicon-based ceramic core; 2. Alumina-based ceramic core skeleton core; 201. Fixed end. Detailed Implementation
[0030] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0031] A method for preparing and removing a ceramic core reinforced with a ceramic core skeleton includes the following steps:
[0032] S1. Prepare an alumina-based ceramic core framework, wherein the ceramic core framework is provided with a fixed end 201;
[0033] S2. Prepare a ceramic core mold according to the design requirements. The ceramic core mold is provided with a positioning groove that matches the fixed end 201.
[0034] S3. Place the ceramic core skeleton into the ceramic core mold and insert the fixed end 201 into the positioning groove;
[0035] S4. First, place the ceramic core mold with the fixed ceramic core skeleton on the core pressing machine, and inject silicon-based ceramic core 1 slurry into the ceramic core mold by injection molding. Then, remove the ceramic core mold to obtain a ceramic core skeleton reinforced ceramic core green body. After sintering, trimming, strengthening and inspection, a ceramic core skeleton reinforced ceramic core composed of alumina-based ceramic core skeleton core 2 and silicon-based ceramic core 1 is obtained, wherein silicon-based ceramic core 1 wraps alumina-based ceramic core skeleton core 2. Remove the fixed end 201 from the qualified ceramic core skeleton reinforced ceramic core.
[0036] S5. When preparing hollow metal castings using qualified ceramic core reinforced ceramic cores, after directional solidification, a metal casting is formed that encapsulates the ceramic core reinforced ceramic core. Then, the silicon-based ceramic core 1 in the ceramic core reinforced ceramic core is removed first, so that a certain gap is left between the alumina-based ceramic core 2 and the inner wall of the metal casting. Then, the alumina-based ceramic core 2 is removed.
[0037] This invention combines the advantages of both silicon-based ceramic core 1 and alumina-based ceramic core skeleton 2 by incorporating an alumina-based ceramic core skeleton 2 inside a conventional silicon-based ceramic core 1. This significantly improves the high-temperature strength and deflection of the silicon-based ceramic core 1 and greatly reduces its fracture rate, thereby increasing the yield of the desired hollow metal castings. Furthermore, after directional solidification, the silicon-based ceramic core 1 is removed from the ceramic core skeleton reinforced ceramic core, leaving a certain gap between the alumina-based ceramic core skeleton 2 and the inner wall of the metal casting. The distance facilitates the removal of the alumina-based ceramic core skeleton 2, thereby significantly shortening the removal cycle of the alumina-based ceramic core skeleton 2. In summary, this method is suitable for the preparation of ceramic cores used in investment casting of oriented crystal and single crystal hollow metal castings such as blades. Moreover, the alumina-based ceramic core skeleton 2 in the obtained ceramic core skeleton reinforced ceramic core is easy to remove, which can solve the problems of low temperature resistance and low strength of traditional silicon-based ceramic cores 1 and the difficulty in removing aluminum-based ceramic cores used in investment casting of oriented crystal and single crystal hollow alloy blades in the background art.
[0038] By inserting the fixed end 201 of the ceramic core skeleton into the positioning groove of the ceramic core mold, the position of the ceramic core skeleton in the ceramic core mold can be guaranteed, preventing the position of the silicon-based ceramic core 1 wrapped on the outside of the ceramic core skeleton from shifting.
[0039] In step S1: if the part that needs to be reinforced in the subsequently obtained silicon-based ceramic core 1 is a straight channel structure, then the ceramic core skeleton is a straight pure alumina rod or pure alumina plate, and the size of the ceramic core skeleton is 10%-90% of the size of the part that needs to be reinforced in the subsequent silicon-based ceramic core 1.
[0040] By designing the size of the ceramic core skeleton to be 10%-90% of the size of the area requiring reinforcement in the subsequent silicon-based ceramic core 1, the silicon-based ceramic core 1 slurry wrapped around the outer side of the ceramic core skeleton will not crack during the pressing process, nor during the sintering process of the resulting ceramic core skeleton-reinforced ceramic core green body, due to the difference in the expansion coefficients between the ceramic core skeleton and the silicon-based ceramic core 1. In addition, during the removal process of the silicon-based ceramic core 1 in the subsequent ceramic core skeleton-reinforced ceramic core, the size design of the ceramic core skeleton ensures that the area requiring reinforcement in the silicon-based ceramic core 1 has a certain thickness. This provides sufficient space for the silicon-based ceramic core 1 to enter and react chemically, meaning that the removal agent of the silicon-based ceramic core 1 has sufficient flow space. Therefore, it is easy to remove the silicon-based ceramic core 1 around the alumina-based ceramic core skeleton 2 in the ceramic core skeleton-reinforced ceramic core.
[0041] In step S1: if there are bent parts in the silicon-based ceramic core 1 that need to be reinforced, a ceramic core skeleton mold is first made as needed. The inner cavity size of the ceramic core skeleton mold is 10%-90% of the size of the part that needs to be reinforced in the silicon-based ceramic core 1. Then, alumina-based ceramic core skeleton slurry 2 is injected into the ceramic core skeleton mold by injection molding. The ceramic core skeleton mold is then removed to obtain an alumina-based ceramic core skeleton green body, which serves as the ceramic core skeleton.
[0042] By designing the inner cavity size of the ceramic core skeleton mold to be 10%-90% of the size of the area requiring reinforcement in the subsequent silicon-based ceramic core 1, the resulting ceramic core skeleton size is 10%-90% of the size of the area requiring reinforcement in the subsequent silicon-based ceramic core 1. This ensures that during the pressing process of the silicon-based ceramic core 1 slurry wrapped around the outer side of the ceramic core skeleton, and during the sintering process of the resulting ceramic core skeleton-reinforced ceramic core green body, the difference in the expansion coefficients of the ceramic core skeleton and the silicon-based ceramic core 1 will not lead to problems with the resulting ceramic core skeleton. The reinforced ceramic core experienced cracking. In addition, during the removal process of the silicon-based ceramic core 1 in the subsequently obtained ceramic core skeleton reinforced ceramic core, the size design of the ceramic core skeleton resulted in a certain thickness in the part of the silicon-based ceramic core 1 that needed to be reinforced. This provided sufficient space for the silicon-based ceramic core 1 to enter and react chemically with the removal agent. In other words, the removal agent of the silicon-based ceramic core 1 had sufficient flow space, thus making it easy to remove the silicon-based ceramic core 1 around the alumina-based ceramic core skeleton 2 in the ceramic core skeleton reinforced ceramic core.
[0043] In step S3, after the ceramic core skeleton is fixed inside the ceramic core mold, the ceramic core skeleton is located at the central position of the silicon-based ceramic core 1 that needs reinforcement in the subsequently obtained ceramic core skeleton-reinforced ceramic core. This effectively improves the high-temperature strength and deflection of the reinforced part of the silicon-based ceramic core 1, and effectively reduces the fracture problem at the reinforced part of the silicon-based ceramic core 1.
[0044] In step S4: the inspection specifically involves checking whether the obtained ceramic core skeleton reinforced ceramic core has cracked due to the presence of alumina-based ceramic core skeleton core 2; the fixed end 201 in the qualified ceramic core skeleton reinforced ceramic core is removed, specifically by physically cutting off or grinding the fixed end 201 in the qualified ceramic core skeleton reinforced ceramic core.
[0045] In step S5: the outer side of the formed metal casting is provided with a ceramic shell. Before removing the silicon-based ceramic core 1, the ceramic shell is removed first.
[0046] In step S5, the silicon-based ceramic core 1 in the ceramic core skeleton reinforced ceramic core is removed by using a 35wt%-45wt% KOH aqueous solution or NaOH aqueous solution under a pressure of 0.2MPa-0.4MPa and a temperature of 115℃-125℃.
[0047] In step S5: if the part that needs to be reinforced in the obtained silicon-based ceramic core 1 is a straight channel structure, then after removing the silicon-based ceramic core 1, the alumina-based ceramic core skeleton core 2 will slide out of the inner cavity of the metal casting to remove the alumina-based ceramic core skeleton core 2.
[0048] In step S5: if there is a bent part in the position that needs to be reinforced in the obtained silicon-based ceramic core 1, after removing the silicon-based ceramic core 1, the alumina-based ceramic core skeleton core 2 in the inner cavity of the metal casting is first broken by physical method, and then cleaned with water to remove the alumina-based ceramic core skeleton core 2.
[0049] In step S5: if there are bent areas at the locations requiring reinforcement in the obtained silicon-based ceramic core 1, then after removing the silicon-based ceramic core 1, an aluminum-based core removal alkali solution is used to remove the alumina-based ceramic core skeleton core 2. Preferably, the aluminum-based core removal alkali solution is a KOH aqueous solution or a NaOH aqueous solution.
[0050] Since the silicon-based ceramic core 1 surrounding the alumina-based ceramic core skeleton 2 has been removed during the removal of the alumina-based ceramic core skeleton 2, a certain gap is left between the alumina-based ceramic core skeleton 2 and the inner cavity wall of the metal casting. The alkaline solution for removing the aluminum core can fully enter the inner cavity of the metal casting and fully react chemically with the alumina-based ceramic core skeleton 2, thus significantly shortening the removal cycle of the alumina-based ceramic core skeleton 2.
[0051] In summary, this invention combines the advantages of silicon-based ceramic core 1 and alumina-based ceramic skeleton core 2, which can effectively shorten the removal cycle of alumina-based ceramic skeleton core 2 while improving the high-temperature strength, deflection and yield of hollow metal castings prepared by silicon-based ceramic core 1.
[0052] Example 1
[0053] A certain single-crystal hollow alloy blade is used in investment casting. Figure 1The traditional silicon-based ceramic core 1 has a large number of transverse grooves on the air intake side channel. During the directional solidification process of the alloy blade, the silicon-based ceramic core 1 is subjected to the scouring of the high-temperature alloy liquid and the tensile force of the solidification of the alloy liquid, making it particularly prone to fracture at the transverse grooves, with a fracture rate of 20%. Furthermore, the fracture-prone position of the silicon-based ceramic core 1 is a simple straight channel structure. Therefore, the required alumina-based ceramic core skeleton core 2 is a straight channel structure.
[0054] To solve the above problems, according to the method of the present invention, the ceramic core skeleton can be made of straight pure alumina rods, thus the problem can be solved by pre-embedding straight pure alumina rods. Figure 1 The fracture problem of silicon-based ceramic core 1, see Figure 2 .
[0055] in Figure 1 The cross-section of the easily fractured part of the silicon-based ceramic core 1 is 2mm*2mm. Figure 2 The selected pure alumina rod has a diameter of 1.3 mm and is used as the alumina-based ceramic core skeleton core 2 in the ceramic core skeleton reinforced ceramic core.
[0056] Figure 2 The method for preparing and removing ceramic cores reinforced with ceramic core skeletons includes the following steps:
[0057] S1, Select Figure 2 The pure alumina rod shown is used as a ceramic core skeleton, wherein one end of the pure alumina rod is a fixed end 201;
[0058] S2. Prepare the corresponding ceramic core mold, wherein a positioning groove with a diameter of 1.3mm is opened on one side of the core head of the ceramic core mold;
[0059] S3. Clamp the pure alumina rod inside the ceramic core mold. At this time, one end of the pure alumina rod is fixed in the positioning groove, and the pure alumina rod is suspended in the corresponding position inside the ceramic core mold.
[0060] S4. First, inject silicon-based ceramic core slurry 1 into the ceramic core mold with the pure alumina rod fixed in place. Then, remove the ceramic core mold to obtain a ceramic core skeleton-reinforced ceramic core green body. After sintering, trimming, strengthening, and inspection, the desired product is obtained. Figure 2 The ceramic core reinforced ceramic core shown has a pure alumina rod as an alumina-based ceramic core 2, and a silicon-based ceramic core 1 surrounding the pure alumina rod. The fixed end 201 outside the core head position in the ceramic core reinforced ceramic core is cut off.
[0061] S5. When preparing single-crystal hollow alloy blades using ceramic core reinforced ceramic cores, after directional solidification, alloy blades are formed that encapsulate the ceramic core reinforced ceramic core. Then, the silicon-based ceramic core 1 in the ceramic core reinforced ceramic core is removed, leaving a certain gap between the alumina-based ceramic core 2 and the inner cavity wall of the alloy blade. After removing the silicon-based ceramic core 1, the pure alumina rod slides out of the inner cavity of the alloy blade.
[0062] This embodiment significantly improves the high-temperature strength and deflection of the silicon-based ceramic core 1 by embedding a pure alumina rod in the core 1, reduces the fracture rate to 0, and allows the silicon-based ceramic core 1 to be removed using conventional methods.
[0063] Example 2
[0064] A certain single-crystal hollow alloy blade is used in investment casting. Figure 3 The traditional silicon-based ceramic core 1 has a large number of transverse grooves on the air intake side channel and a bend. During the directional solidification of the alloy blade, the silicon-based ceramic core 1 is subjected to the scouring of the high-temperature alloy liquid and the tensile force of the solidification of the alloy liquid, making it particularly prone to breakage at the transverse grooves and the bend, with a breakage rate of 30%. Furthermore, the silicon-based ceramic core 1 has a bend at the easily breakable position, thus forming a complex irregular structure. Therefore, the required alumina-based ceramic core skeleton core 2 also has a bend.
[0065] To solve the above problems, according to the method of the present invention, Figure 4 The method for preparing and removing ceramic cores reinforced with ceramic core skeletons includes the following steps:
[0066] S1. First, make a ceramic core skeleton mold as needed. The inner cavity size of the ceramic core skeleton mold is 60% of the size of the part that needs to be reinforced in the subsequent silicon-based ceramic core 1. Then, inject alumina-based ceramic core skeleton 2 slurry with an alumina content of 85% into the ceramic core skeleton mold. Then remove the ceramic core skeleton mold to obtain the alumina-based ceramic core skeleton green body and use it as the ceramic core skeleton.
[0067] S2. Prepare the corresponding ceramic core mold, wherein positioning grooves are opened on both sides of the core head of the ceramic core mold to match the fixed ends 201 at both ends of the alumina-based ceramic core skeleton core blank.
[0068] S3. Clamp the pure alumina rod in the ceramic core mold. At this time, the two ends of the alumina-based ceramic core skeleton green blank are fixed in the corresponding positioning grooves of the ceramic core mold, and the alumina-based ceramic core skeleton green blank is suspended in the corresponding position in the ceramic core mold.
[0069] S4. First, inject silicon-based ceramic core slurry 1 into the ceramic core mold that has the alumina-based ceramic core skeleton core green body fixed. Then, remove the ceramic core mold to obtain the ceramic core skeleton reinforced ceramic core green body. After sintering, trimming, strengthening, and inspection, the desired product is obtained. Figure 4 The ceramic core reinforced by the ceramic core skeleton shown is composed of an alumina-based ceramic core skeleton 2 and a silicon-based ceramic core 1, and the fixed end 201 on the outside of the core head position in the ceramic core skeleton reinforced ceramic core is cut off.
[0070] S5. When preparing single-crystal hollow alloy blades using ceramic core reinforced ceramic cores, after directional solidification, alloy blades are formed that encapsulate the ceramic core reinforced ceramic core. Then, the silicon-based ceramic core 1 in the ceramic core reinforced ceramic core is removed using conventional methods, leaving a certain gap between the alumina-based ceramic core 2 and the inner wall of the alloy blade. Specifically, the gap size around the alumina-based ceramic core 2 is 40% of the size of the part in the silicon-based ceramic core 1 that needs reinforcement. Then, the alumina-based ceramic core 2 is quickly removed using the removal process.
[0071] In this embodiment, because an irregularly shaped alumina-based ceramic core skeleton 2 is embedded in the silicon-based ceramic core 1, the high-temperature strength and deflection of the silicon-based ceramic core 1 are significantly improved, the fracture rate is reduced to 0, and the alumina-based ceramic core skeleton 2 can be removed by conventional methods, shortening the removal cycle by 80%.
[0072] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing and removing a ceramic core reinforced with a ceramic core skeleton, characterized in that, Includes the following steps: S1. Prepare an alumina-based ceramic core framework, wherein the ceramic core framework is provided with a fixed end (201). S2. Prepare a ceramic core mold, wherein the ceramic core mold is provided with a positioning groove that is adapted to the fixed end (201); S3. Place the ceramic core skeleton into the ceramic core mold and insert the fixed end (201) into the positioning groove; S4. First, inject silicon-based ceramic core (1) slurry into the ceramic core mold with the ceramic core skeleton fixed, then remove the ceramic core mold to obtain a ceramic core skeleton reinforced ceramic core green body, and then sinter, trim, strengthen and inspect to obtain a ceramic core skeleton reinforced ceramic core composed of alumina-based ceramic core skeleton core (2) and silicon-based ceramic core (1), and remove the fixed end (201) in the qualified ceramic core skeleton reinforced ceramic core; S5. When preparing a hollow metal casting using the qualified ceramic core reinforced ceramic core, after directional solidification, a metal casting is formed that encapsulates the ceramic core reinforced ceramic core. Then, the silicon-based ceramic core (1) in the ceramic core reinforced ceramic core is removed first, so that a certain gap is left between the alumina-based ceramic core (2) and the inner wall of the metal casting. Then, the alumina-based ceramic core (2) is removed.
2. The method for preparing and removing a ceramic core reinforced with a ceramic core skeleton according to claim 1, characterized in that, In step S1: If the part that needs to be reinforced in the subsequently obtained silicon-based ceramic core (1) is a straight channel structure, then the ceramic core skeleton is a straight pure alumina rod or pure alumina plate, and the size of the ceramic core skeleton is 10%-90% of the size of the part that needs to be reinforced in the subsequent silicon-based ceramic core (1).
3. The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to claim 1, characterized in that, In step S1: If there is a bent part in the position that needs to be reinforced in the silicon-based ceramic core (1) obtained later, a ceramic core skeleton mold is first made as needed. The inner cavity size of the ceramic core skeleton mold is 10%-90% of the size of the part that needs to be reinforced in the silicon-based ceramic core (1) later. Then, alumina-based ceramic core skeleton core (2) slurry is injected into the ceramic core skeleton mold. Then, the ceramic core skeleton mold is removed to obtain an alumina-based ceramic core skeleton green body and use it as a ceramic core skeleton.
4. The method for preparing and removing a ceramic core reinforced with a ceramic core skeleton according to claim 1, characterized in that, In step S3: After the ceramic core skeleton is fixed inside the ceramic core mold, the ceramic core skeleton is located in the middle position of the silicon-based ceramic core (1) that needs to be reinforced in the ceramic core skeleton reinforced ceramic core to be obtained later.
5. The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to claim 1, characterized in that, In step S4: the inspection specifically involves checking whether the obtained ceramic core skeleton reinforced ceramic core has cracked due to the presence of the alumina-based ceramic core skeleton core (2); the fixed end (201) in the qualified ceramic core skeleton reinforced ceramic core is removed, specifically by physically cutting off or grinding the fixed end (201) in the qualified ceramic core skeleton reinforced ceramic core.
6. The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to claim 1, characterized in that, In step S5: The outer side of the formed metal casting is provided with a ceramic shell. Before removing the silicon-based ceramic core (1), the ceramic shell is removed first.
7. The method for preparing and removing a ceramic core reinforced with a ceramic core skeleton according to claim 1, characterized in that, In step S5: the silicon-based ceramic core (1) in the ceramic core skeleton reinforced ceramic core is removed, specifically by using a 35wt%-45wt% KOH aqueous solution or NaOH aqueous solution under a pressure of 0.2MPa-0.4MPa and a temperature of 115℃-125℃ to remove the silicon-based ceramic core (1).
8. The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to claim 1, characterized in that, In step S5: If the part that needs to be reinforced in the obtained silicon-based ceramic core (1) is a straight channel structure, then after removing the silicon-based ceramic core (1), the alumina-based ceramic core skeleton core (2) will slide out of the inner cavity of the metal casting to remove the alumina-based ceramic core skeleton core (2).
9. The method for preparing and removing a ceramic core reinforced with a ceramic core framework according to claim 1, characterized in that, In step S5: If there is a bent part in the position that needs to be reinforced in the obtained silicon-based ceramic core (1), after removing the silicon-based ceramic core (1), the alumina-based ceramic core skeleton core (2) in the inner cavity of the metal casting is first broken by physical method, and then cleaned with water to remove the alumina-based ceramic core skeleton core (2).
10. The method for preparing and removing a ceramic core reinforced with a ceramic core skeleton according to claim 1, characterized in that, In step S5: If there is a bent part in the position that needs to be reinforced in the obtained silicon-based ceramic core (1), after removing the silicon-based ceramic core (1), the alumina-based ceramic core skeleton core (2) is removed by using an aluminum-based core removal alkali solution.