Integrated complex-structure ceramic core and preparation method thereof

Abstract

The invention relates to the technical field of precision casting, in particular to an integrated complex-structure ceramic core and a preparation method thereof. Comprising the following steps: (1) mold design; (2) pressure injection molding; and (3) degreasing and sintering. According to the preparation method of the integrated ceramic core with the complex structure, the ceramic core main body structure and the core accessory structure can be integrally formed, assembly is not needed, the performance of the joint of the accessory structure and the ceramic core main body structure is improved, the performance continuity and the structural integrity of the core are improved, and meanwhile, the product quality is improved. According to the integrated mold core preparation method, the position deviation of an accessory structure and a main body structure in combined preparation can be avoided, and the accuracy of the overall size of the mold core is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of precision casting technology, specifically to an integrated complex structure ceramic core and its preparation method. Background Technology

[0002] In aero-engine and gas turbine components, operating in high-temperature environments, parts rely on hollow air-cooled structures for cooling. The more complex the cooling structure, the higher the cooling effect. Ceramic cores are key components in forming these hollow air-cooled structures, and their structures are becoming increasingly complex to improve cooling efficiency. Ceramic cores are typically produced using hot-press molding, where ceramic slurry is injected into a pre-designed mold. After the slurry solidifies, the mold is separated, and the core is subsequently subjected to high-temperature treatment. As the core structure becomes more complex, mold separation becomes more difficult, especially when there are auxiliary structures on the main body of the ceramic core, making it impossible to obtain the ceramic core using ordinary mold separation methods.

[0003] In existing technologies, for ceramic cores with auxiliary structures on the main body, the common manufacturing method is to separately mold and sinter the main body and auxiliary parts, and then assemble them using high-temperature structural adhesive. This assembly process requires specialized tooling for precise positioning; otherwise, the relative dimensions of the auxiliary structures cannot be guaranteed. Furthermore, due to the use of a combined structure, insufficient temperature resistance at the connection points may lead to the detachment or breakage of the auxiliary structures during subsequent use. Therefore, developing a method for integrally molding complex-structure ceramic cores is of great significance. In view of this, this invention provides an integrated complex-structure ceramic core and its manufacturing method. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide an integrated complex-structure ceramic core and its preparation method. The aim is to integrally hot-press the auxiliary structure with the main structure of the ceramic core, thereby eliminating the problems of low connection performance and difficulty in ensuring assembly dimensions that exist in the prior art when the parts are manufactured separately and then assembled.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: Firstly, the method for preparing an integrated, complex-structured ceramic core includes the following steps: (1) Mold design: (1-1) The ceramic core consists of a ceramic core body and an auxiliary structure disposed on the ceramic core body. The auxiliary structure is modified in a block shape to form a standard or regular shape, thereby obtaining the modified auxiliary structure. (1-2) Design a mold for the ceramic core with the modified auxiliary structure to obtain a mold for the ceramic core; design an upper modified body mold and a lower modified body mold for the auxiliary structure according to the modified auxiliary structure; (2) Injection molding: (2-1) Preparation of water-soluble modified body: Water-soluble molding material is injected into the upper modified body mold and the lower modified body mold to obtain water-soluble upper modified body and water-soluble lower modified body; (2-2) Hot press molding: The water-soluble upper modifier and the water-soluble lower modifier are loaded into the mold of the ceramic core, and the ceramic core slurry is injected into the mold of the ceramic core through hot press molding to obtain a wet ceramic core blank with water-soluble modifier encapsulating the auxiliary structure; (2-3) Removal of water-soluble modifier: The wet ceramic core blank with the attached structure wrapped by the water-soluble modifier is placed in water or acidified water to remove the water-soluble modifier and obtain the unglazed blank of the integrated complex structure ceramic core. (3) Degreasing and sintering: The green blank of the integrated complex structure ceramic core is subjected to powder degreasing and sintering treatment to obtain the integrated complex structure ceramic core.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, in step (1-2), the design of the upper and lower decorative body molds for the modified auxiliary structure includes the following specific steps: removing the modified block of the modified auxiliary structure to obtain the modified body of the auxiliary structure; using the auxiliary structure as the cavity of the modified body of the auxiliary structure, cutting the modified body of the auxiliary structure along the cavity to obtain the upper and lower decorative bodies; and performing mold parting design with the upper and lower decorative bodies to obtain the upper decorative body mold and the lower decorative body mold.

[0008] Furthermore, the auxiliary structure includes at least one of the following: L-shaped auxiliary structure, T-shaped auxiliary structure, circular auxiliary structure, C-shaped auxiliary structure, and cross-shaped auxiliary structure.

[0009] Furthermore, the water-soluble molding material mentioned in step (2-1) is at least one of urea, water-soluble wax, inorganic salt-bonded ceramic material, and water-soluble salt.

[0010] Furthermore, the specific method of injecting the water-soluble molding material into the upper and lower decorative body molds in step (2-1) includes at least one of injection molding, slurry casting, and gel injection molding.

[0011] Furthermore, the ceramic core slurry mentioned in step (2-2) is any one of silica ceramic core slurry, alumina ceramic core slurry, and zirconia ceramic core slurry.

[0012] Furthermore, the parameters for hot injection molding in step (2-2) are: injection temperature of 70℃~120℃, flow rate of 200cc / s~400cc / s, mold temperature of 20℃~50℃, injection pressure of 2 MPa~8 MPa, injection time of 20s~60s, and holding time of 20s~60s.

[0013] Furthermore, the acidified water mentioned in step (2-3) includes at least one of the following: a citric acid aqueous solution with a mass content of 2% to 15%, an acetic acid aqueous solution with a mass content of 2% to 15%, an acetic acid solution with a mass content of 2% to 10%, and an oxalic acid solution with a mass content of 2% to 10%.

[0014] Furthermore, the parameters for the powder degreasing and sintering treatment in step (3) are as follows: the temperature is increased to 300℃~400℃ at 15℃ / h~35℃ / h, then increased to 600℃~700℃ at 10℃ / h~25℃ / h, then increased to 1100℃~1300℃ at 50℃ / h~100℃ / h, held for 2h~6h, and then cooled down with the furnace.

[0015] Secondly, an integrated complex structure ceramic core is prepared by the aforementioned preparation method.

[0016] The beneficial effects of this invention are: Compared with the prior art, the integrated complex structure ceramic core preparation method provided by the present invention can integrally form the main structure of the ceramic core and the auxiliary structure of the core without assembly, which improves the performance of the connection between the auxiliary structure and the main structure of the ceramic core, enhances the continuity of core performance and structural integrity. At the same time, the integrated core preparation method can avoid the positional deviation between the auxiliary structure and the main structure during the assembly process, ensuring the accuracy of the overall size of the core. Attached Figure Description

[0017] Figure 1 A schematic diagram of a ceramic core with the modified auxiliary structure described above; Figure 2 These are schematic diagrams of partial structures of the ceramic core in Embodiments 1 and 2 of the present invention; Figure 3 This is a schematic diagram of the cross-sectional structure of the core mold in an embodiment of the present invention.

[0018] The attached diagram lists the components represented by each number as follows: 1 - Ceramic core body; 2 - Auxiliary structure; 3 - Upper decorative body; 4 - Lower decorative body; 5 - Decorative body positioning structure; 6 - Ceramic core mold. Detailed Implementation

[0019] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they should be performed according to the techniques or conditions described in the literature in this field, or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0020] This embodiment relates to a method for preparing an integrated complex structure ceramic core, including the following steps: (1) Mold design: (1-1) The ceramic core consists of a ceramic core body 1 and an auxiliary structure 2 disposed on the ceramic core body 1. The auxiliary structure 2 is modified in a block shape to obtain a modified auxiliary structure 2. (1-2) Design a mold for the ceramic core with the modified auxiliary structure 2 to obtain a mold 6 for the ceramic core; design an upper modified body 3 mold and a lower modified body 4 mold for the auxiliary structure 2 according to the modified auxiliary structure 2. (2) Injection molding: (2-1) Preparation of water-soluble modified body: Water-soluble molding material is injected into the mold of the upper modified body 3 and the mold of the lower modified body 4 to obtain water-soluble upper modified body 3 and water-soluble lower modified body 4; (2-2) Hot press molding: The water-soluble upper modifier 3 and the water-soluble lower modifier 4 are loaded into the mold 6 of the ceramic core, and the ceramic core slurry is injected into the mold 6 of the ceramic core through hot press molding to obtain a ceramic core wet blank in which the water-soluble modifier encapsulates the auxiliary structure 2; wherein, the mold 6 of the ceramic core is prepared according to conventional process; (2-3) Removal of water-soluble modifier: The wet ceramic core blank of the attached structure 2 wrapped with the water-soluble modifier is placed in water or acidified water to remove the water-soluble modifier and obtain the unglazed blank of the integrated complex structure ceramic core. (3) Degreasing and sintering: The green blank of the integrated complex structure ceramic core is subjected to powder degreasing and sintering treatment to obtain the integrated complex structure ceramic core.

[0021] Preferably, in this embodiment, step (1-2) of designing the upper decorative body 3 mold and the lower decorative body 4 mold for the modified auxiliary structure 2 includes the following specific steps: removing the decorative block of the modified auxiliary structure 2 to obtain the decorative body of the auxiliary structure 2; using the auxiliary structure 2 as the cavity of the decorative body of the auxiliary structure 2, cutting the decorative body of the auxiliary structure 2 along the cavity to obtain the upper decorative body 3 and the lower decorative body 4; and performing a parting design using the upper decorative body 3 and the lower decorative body 4 to obtain the upper decorative body 3 mold and the lower decorative body 4 mold. The upper decorative body 3 mold and the lower decorative body 4 mold can be made of aluminum alloy. The upper decorative body 3 mold and the lower decorative body 4 mold also include a decorative body positioning structure 5.

[0022] A ceramic core with an auxiliary structure 2 refers to a core with a complex auxiliary structure 2 located outside the main core structure, making it difficult to separate from the main core through molding. Preferably, in this embodiment, the auxiliary structure 2 includes at least one of the following: L-shaped auxiliary structure 2, T-shaped auxiliary structure 2, disc-shaped auxiliary structure 2, C-shaped auxiliary structure 2, and cross-shaped auxiliary structure 2. Figure 1 As shown.

[0023] Preferably, the water-soluble molding material in step (2-1) of this embodiment is at least one of urea, water-soluble wax, inorganic salt-bonded ceramic material, and water-soluble salt. The specific method for injecting the water-soluble molding material into the upper modifying body 3 mold and the lower modifying body 4 mold in step (2-1) includes at least one of injection molding, slip casting, and gel injection molding.

[0024] Preferably, the ceramic core slurry mentioned in step (2-2) of this embodiment is any one of silica ceramic core slurry, alumina ceramic core slurry, and zirconia ceramic core slurry. The parameters for hot press molding in step (2-2) are: injection temperature of 70℃~120℃, flow rate of 200 cc / s~400 cc / s, mold temperature of 20℃~50℃, injection pressure of 2 MPa~8 MPa, injection time of 20s~60s, and holding time of 20s~60s.

[0025] Preferably, the acidified water in step (2-3) of this embodiment includes at least one of the following: a citric acid aqueous solution with a mass content of 2% to 15%, an acetic acid aqueous solution with a mass content of 2% to 15%, an acetic acid solution with a mass content of 2% to 10%, and an oxalic acid solution with a mass content of 2% to 10%.

[0026] Preferably, the parameters for the powder degreasing and sintering treatment in step (3) of this embodiment are as follows: heating to 300℃~400℃ at 15℃ / h~35℃ / h, then heating to 600℃~700℃ at 10℃ / h~25℃ / h, then heating to 1100℃~1300℃ at 50℃ / h~100℃ / h, holding for 2h~6h, and then cooling down with the furnace.

[0027] This embodiment also relates to an integrated complex structure ceramic core, which is prepared by the aforementioned preparation method.

[0028] The following is a further explanation using specific examples: Example 1: In this embodiment, the complex-structured ceramic core has two circular-shaped appendages on the main body 1 of the ceramic core, as shown in the structural diagram. Figure 2 As shown.

[0029] The method for fabricating an integrated, complex-structured ceramic core includes the following steps: Mold Design: The circular plate-shaped auxiliary structure 2 of the ceramic core in the basin and back directions is modified, and a standard cylinder is used to replace the circular plate-shaped auxiliary structure 2; the modified standard cylinder and the main body 1 of the ceramic core form a new core body; the new core body is designed for mold separation to obtain the mold 6 of the ceramic core; using the original circular plate-shaped auxiliary structure 2 as the cavity of the modified cylinder, the obtained standard cylinder is cut along the circular plate-shaped auxiliary structure 2 of the core to obtain the upper modified body 3 and the lower modified body 4; the upper modified body 3 and the lower modified body 4 are designed as mold objects separately to obtain the mold of the upper modified body 3 and the mold of the lower modified body 4. Figure 3 ).

[0030] Preparation of water-soluble modified body: Water-soluble wax is injected into the mold of upper modified body 3 and lower modified body 4 to obtain water-soluble upper modified body 3 and lower modified body 4.

[0031] Hot-press molding step: The water-soluble upper modifier 3 and lower modifier 4 are loaded into the mold 6 of the ceramic core. Silica-based ceramic core slurry is injected into the mold 6 of the ceramic core through hot-press molding to obtain a wet ceramic core blank in which the water-soluble modifier encapsulates the auxiliary structure 2. The parameters for hot-press molding are: injection temperature 85℃, flow rate 400 cc / s, mold temperature 35℃, injection pressure 6 MPa, injection time 30s, and holding time 40s.

[0032] Water-soluble modifier removal step: Place the wet ceramic core blank of the attached structure 2, which is covered by the water-soluble modifier, in a 10% citric acid aqueous solution to remove the water-soluble modifier and obtain the green blank of the integrated complex structure ceramic core.

[0033] Degreasing and sintering steps: The ceramic core integral molding green body is subjected to powder embedding degreasing and sintering treatment to obtain the ceramic core integral molding sintered part. The parameters for powder embedding degreasing and sintering treatment are: heating to 300℃ at 15℃ / h, then heating to 600℃ at 15℃ / h, then heating to 1200℃ at 100℃ / h, holding at that temperature for 4 hours, and then cooling down with the furnace.

[0034] Example 2: The complex structure ceramic core prepared in this embodiment is the same as that in Example 1, except that; Preparation steps of water-soluble modified body: Inorganic salt-bonded ceramic slurry is injected into the mold of upper modified body 3 and lower modified body 4 by gel casting until solidification, to obtain water-soluble upper modified body 3 and lower modified body 4 green body. After firing with inorganic salt-bonded ceramic core, the inorganic salt-bonded ceramic core of upper modified body 3 and lower modified body 4 is obtained.

[0035] Hot-press molding step: The upper modifier 3 and lower modifier 4 are loaded into the mold 6 of the ceramic core. Silica-based ceramic core slurry is injected into the mold 6 of the ceramic core through hot-press molding to obtain a wet ceramic core blank with the water-soluble modifier encapsulating the auxiliary structure 2. The parameters for hot-press molding are: injection temperature 100℃, flow rate 200 cc / s, mold temperature 40℃, injection pressure 8 MPa, injection time 30s, and holding time 50s.

[0036] Water-soluble modifier removal step: Place the wet ceramic core blank of the attached structure 2, which is wrapped with water-soluble modifier, into flowing pure water. After the inorganic salt in the modifier dissolves, the modifier collapses, and a green blank of an integrated complex structure ceramic core is obtained.

[0037] Degreasing and sintering steps: The ceramic core integral molding green body is subjected to powder embedding degreasing and sintering treatment to obtain the ceramic core integral molding sintered part. The parameters for powder embedding degreasing and sintering treatment are: heating to 400℃ at 25℃ / h, then heating to 700℃ at 20℃ / h, then heating to 1150℃ at 80℃ / h, holding at that temperature for 6h, and then cooling down with the furnace.

[0038] Comparative Example 1 The complex structure ceramic core prepared in this embodiment is the same as that in Example 1, except that; The parameters for the powder degreasing and sintering treatment were as follows: heating rate of 50℃ / h to 1200℃, holding for 4 hours and then cooling with the furnace. The rest were exactly the same as in Example 1.

[0039] Comparative Example 2 The complex structure ceramic core prepared in this embodiment is the same as that in Example 1, except that; The ceramic core body 1 and the auxiliary structure 2 are respectively injection molded and sintered with powder. The sintered ceramic core body 1 and the auxiliary structure 2 are combined together by mortise and tenon structure to form a complete core structure. High temperature ceramic adhesive is used to bond and fix the joint surface of the ceramic core body 1 and the auxiliary structure 2 during the mortise and tenon combination process.

[0040] Test case (1) The silicon-based ceramic cores obtained in Examples 1-2 and the ceramic cores of Comparative Examples 1-2 were tested according to the relevant test methods recorded in HB5353-2004 to test the core flexural strength (high temperature flexural strength) and the connection strength between the core body and the auxiliary structure 2 (high temperature flexural strength).

[0041] (2) Statistical analysis of the dimensional accuracy of the auxiliary structure 2 of the ceramic core and the crack rate of the connection between the auxiliary structure 2 and the main body 1 of the ceramic core.

[0042] The results are shown in Table 1: Table 1 As shown in Table 1, in Examples 1 and 2, the integrated ceramic core was prepared according to the implementation scheme of the present invention. The connection strength between the ceramic core body 1 and the auxiliary structure 2 was basically equivalent to the strength of the ceramic core body 1, and the dimensional accuracy of the auxiliary structure 2 was high, with the crack rate at the connection position controlled at an extremely low level. In Example 3, because the heating rate of the debinding sintering was changed, the ceramic core body 1 and the auxiliary structure 2 had large dimensional differences, and the debinding sintering was uneven, resulting in stress. This caused a decrease in the performance of the connection position and an increase in cracks, which shows the advantageous effect of the debinding sintering treatment parameters in the present invention on the core quality. In Example 4, the combination method was used. The connection strength between the ceramic core body 1 and the auxiliary structure 2 was much lower than the performance of the core body, and the manual combination made it difficult to guarantee the dimensional accuracy.

[0043] In summary, the integrated complex structure ceramic core preparation method provided by this invention can integrally form the ceramic core body 1 and the core auxiliary structure 2 without assembly, thereby improving the performance at the connection between the auxiliary structure 2 and the ceramic core body 1, enhancing the continuity of core performance and structural integrity. At the same time, the integrated core preparation method can avoid positional deviations between the auxiliary structure 2 and the main structure during assembly, ensuring the accuracy of the overall core dimensions.

[0044] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing an integrated complex-structure ceramic core, characterized in that, Includes the following steps: (1) Mold design: (1-1) The ceramic core consists of a ceramic core body and an auxiliary structure disposed on the ceramic core body. The auxiliary structure is modified in a block shape to form a standard or regular shape, thereby obtaining the modified auxiliary structure. (1-2) Design a mold for the ceramic core with the modified auxiliary structure to obtain a mold for the ceramic core; design an upper modified body mold and a lower modified body mold for the auxiliary structure according to the modified auxiliary structure; (2) Injection molding: (2-1) Preparation of water-soluble modified body: Water-soluble molding material is injected into the upper modified body mold and the lower modified body mold to obtain water-soluble upper modified body and water-soluble lower modified body; (2-2) Hot press molding: The water-soluble upper modifier and the water-soluble lower modifier are loaded into the mold of the ceramic core, and the ceramic core slurry is injected into the mold of the ceramic core through hot press molding to obtain a wet ceramic core blank with water-soluble modifier encapsulating the auxiliary structure; (2-3) Removal of water-soluble modifier: The wet ceramic core blank with the attached structure wrapped by the water-soluble modifier is placed in water or acidified water to remove the water-soluble modifier and obtain the unglazed blank of the integrated complex structure ceramic core. (3) Degreasing and sintering: The green blank of the integrated complex structure ceramic core is subjected to powder degreasing and sintering treatment to obtain the integrated complex structure ceramic core.

2. The method for preparing the integrated complex structure ceramic core according to claim 1, characterized in that, Step (1-2) involves designing the upper and lower decorative body molds for the modified auxiliary structure, including the following specific steps: removing the modified block of the modified auxiliary structure to obtain the modified body of the auxiliary structure; using the auxiliary structure as the cavity of the modified body of the auxiliary structure, cutting the modified body of the auxiliary structure along the cavity to obtain the upper and lower decorative bodies; and performing mold parting design using the upper and lower decorative bodies to obtain the upper decorative body mold and the lower decorative body mold.

3. The method for preparing the integrated complex structure ceramic core according to claim 1 or 2, characterized in that, The auxiliary structure includes at least one of the following: L-shaped auxiliary structure, T-shaped auxiliary structure, circular auxiliary structure, C-shaped auxiliary structure, and cross-shaped auxiliary structure.

4. The method for preparing the integrated complex structure ceramic core according to claim 1, characterized in that, The water-soluble molding material mentioned in step (2-1) is at least one of urea, water-soluble wax, inorganic salt-bonded ceramic material, and water-soluble salt.

5. The method for preparing the integrated complex structure ceramic core according to claim 4, characterized in that, The specific method of injecting water-soluble molding material into the upper and lower decorative body molds in step (2-1) includes at least one of injection molding, slurry casting, and gel injection molding.

6. The method for preparing the integrated complex structure ceramic core according to claim 1, characterized in that, The ceramic core slurry mentioned in step (2-2) is any one of silica ceramic core slurry, alumina ceramic core slurry, or zirconia ceramic core slurry.

7. The method for preparing the integrated complex structure ceramic core according to claim 6, characterized in that, The parameters for hot injection molding in step (2-2) are: injection temperature of 70℃~120℃, flow rate of 200 cc / s~400 cc / s, mold temperature of 20℃~50℃, injection pressure of 2 MPa~8 MPa, injection time of 20s~60s, and holding time of 20s~60s.

8. The method for preparing the integrated complex structure ceramic core according to claim 1, characterized in that, The acidified water mentioned in step (2-3) includes at least one of the following: a citric acid aqueous solution with a mass content of 2% to 15%, an acetic acid aqueous solution with a mass content of 2% to 15%, an acetic acid solution with a mass content of 2% to 10%, and an oxalic acid solution with a mass content of 2% to 10%.

9. The method for preparing the integrated complex structure ceramic core according to claim 1, characterized in that, The parameters for the powder degreasing and sintering treatment in step (3) are as follows: heat up to 300℃~400℃ at 15℃ / h~35℃ / h, then heat up to 600℃~700℃ at 10℃ / h~25℃ / h, then heat up to 1100℃~1300℃ at 50℃ / h~100℃ / h, hold for 2h~6h, and then cool down with the furnace.

10. An integrated, complex-structured ceramic core, characterized in that: The integrated complex structure ceramic core is prepared by the preparation method described in any one of claims 1 to 9.

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