Ceramic core for blade with complex multi-layer wall and hollow flange structure and its preparation method

Abstract

The present invention discloses a ceramic core for a blade with a complex multi-layer wall and hollow flange structure and a preparation method thereof. The ceramic core includes a ceramic core for a blade with a complex multi-layer wall structure and a ceramic core for a blade with a hollow flange structure. The ceramic core for a blade with a complex multi-layer wall structure includes a complex multi-layer wall core structure, an L-shaped structure, and a T-shaped structure, wherein one end of the T-shaped structure is combined and connected with the ceramic core for a blade with a hollow flange structure in a tenon-mortise manner. The preparation method includes the following steps: preparing a water-soluble core material according to design requirements; preparing a ceramic core for a blade with a complex multi-layer wall structure by a water-soluble core method; and forming the ceramic core for a blade with a hollow flange structure and the cylindrical structure and elliptical hemispherical structure in the T-shaped structure in a tenon-mortise manner. The present invention can prepare a complete ceramic core for a blade with a complex multi-layer wall and hollow flange structure, and the ceramic core has a complete structure, precise dimensions, and high stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic core preparation, and particularly relates to a ceramic core for a blade with a complex multi-layer wall and hollow flange structure and a preparation method thereof. Background Art

[0002] As is well known, a turbine blade is the first core component of an aeroengine, and its working temperature directly determines the thrust-to-weight ratio of the aeroengine. With the continuous increase of the turbine inlet temperature of the aeroengine, the turbine blade needs to adopt a more advanced air-cooling method to obtain higher temperature resistance. The cooling method of the turbine blade has developed from the initial solid non-cooling to impingement cooling, film cooling and compound cooling, and has now developed to a double-layer wall cooling structure and a complex multi-layer wall ultra-cooling structure. And this complex multi-layer wall cooling structure needs to rely on a ceramic core for molding, but due to the multi-layer structure of the ceramic core itself, the preparation difficulty is much higher than that of the ceramic core for the previous single-layer wall structure, mainly manifested as difficult molding, poor dimensional stability, etc.

[0003] The invention patent with the application publication number of CN105127373A discloses a preparation method of a hollow ceramic core for a double-layer wall hollow blade, including the following steps: (1) adopting an injection molding method to form an inner core, and performing high-temperature carbonization treatment on the formed inner core under vacuum or inert gas protection; (2) embedding the obtained inner core in a metal mold for preparing a ceramic core, and adopting an injection molding method to form the ceramic core; (3) sintering the obtained ceramic core by a powder-embedded sintering method. During the sintering process, the embedded inner core reacts in an oxygen environment to generate gas and is removed, and finally a hollow ceramic core for a double-layer wall hollow blade is obtained. The preparation method of this technical solution is relatively complex, requires inert gas protection, and there is easily residue in the internal core, which is not suitable for industrial production.

[0004] The invention patent with the application publication number of CN105562613A discloses a one-step forming method of a ceramic core for a porous laminated divergent cooling turbine blade of an aeroengine, including the following steps: designing a plurality of soluble process components according to the structural characteristics of the inner cavity and the outer cavity of the ceramic core, and respectively pressing and forming each soluble process component with a separate mold; placing all the soluble process components into an overall ceramic core mold through the positioning structure between them to press the overall ceramic core; after the pressing is completed, dissolving the soluble process components to obtain the ceramic core for the porous laminated divergent cooling turbine blade of the aeroengine. In this technical solution, the material of the soluble process component is wax, and its strength is too low, and it is easy to deform, bend and break during the preparation of the ceramic core, and the yield of the ceramic core is relatively low.

[0005] In view of the prior art, there are some documents recording the preparation techniques of ceramic cores for double-layer wall and multi-layer sandwich structure hollow blades. However, these techniques all have some defects and cannot prepare the ceramic cores completely. For example, due to the too low strength of the water-soluble cores, cracks are likely to occur during the pressing process, resulting in the failure of the ceramic cores to be formed, the preparation process is complex, the dimensional accuracy is low, and it is easy to have residues in the internal cores. Therefore, how to prepare ceramic cores for complex multi-layer wall and hollow flange structure blades with high performance, complex structure, small local dimensions and high yield rate by using existing industrial equipment is an urgent need for those skilled in the art. Summary of the Invention

[0006] To solve the problems existing in the prior art, the present invention provides a ceramic core for complex multi-layer wall and hollow flange structure blades, including a ceramic core for complex multi-layer wall structure blades and a ceramic core for hollow flange structure blades, both of which are integrally formed structures; the ceramic core for complex multi-layer wall structure blades includes a complex multi-layer wall core structure, an L-shaped structure and a T-shaped structure. One end of the L-shaped structure is fixedly connected to the complex multi-layer wall core structure, the other end of the L-shaped structure is fixedly connected to one end of the T-shaped structure, and the other end of the T-shaped structure is combined and connected to the ceramic core for hollow flange structure blades in a tenon-mortise manner; the ceramic core for hollow flange structure blades, the L-shaped structure and the T-shaped structure form a hollow flange core structure.

[0007] Preferably, the cross-section of the L-shaped structure is circular, and its diameter is 2-3 mm; the T-shaped structure is sequentially composed of a cuboid structure, a cylinder structure and an elliptical hemisphere structure from bottom to top; the length of the cuboid structure is 8-10 mm, the width is 8-10 mm, and the height is 5-8 mm; the height of the cylinder structure is 5-8 mm, the cross-section of the cylinder structure is elliptical, the short side length of the ellipse is 4-6 mm, and the long side length is 1.2-1.5 times the short side length; the elliptical hemisphere structure is a structure cut along the central plane where the long side of the ellipse is located, and the short side length of the elliptical hemisphere structure is 4-6 mm, and the long side length is 1.2-1.5 times the short side length.

[0008] Preferably in any of the above solutions, the ceramic core for hollow flange structure blades is a cuboid structure, the length of the cuboid structure is 15-18 mm, the width is 15-18 mm, and the height is 8-13 mm.

[0009] Preferably, in any of the above solutions, a groove is formed at the center of the bottom of the ceramic core for the hollow flange structure blade. The groove is combined and connected with the cylindrical structure and the elliptical hemispherical structure in the T-shaped structure in a mortise and tenon manner, and a gap of 0.5-1 mm is evenly formed between the inner wall of the groove and the outer walls of the cylindrical structure and the elliptical hemispherical structure; a bonding adhesive with a thickness of 0.5-1 mm is evenly coated on the outer walls of the cylindrical structure and the elliptical hemispherical structure.

[0010] Preferably, in any of the above solutions, the distance from the vertex of the groove to the top surface of the ceramic core for the hollow flange structure blade is 3-5 mm, and the distance from the vertex of the groove to the bottom surface of the ceramic core for the hollow flange structure blade is 5-8 mm.

[0011] The present invention also provides a preparation method for a ceramic core for a blade with a complex multi-layer wall and a hollow flange structure, which is used to prepare the ceramic core for a blade with a complex multi-layer wall and a hollow flange structure described in any one of the above, and includes the following steps in sequence:

[0012] Step 1: Prepare a water-soluble core material according to the design requirements;

[0013] Step 2: Press a water-soluble sandwich core for the ceramic core of the complex multi-layer wall structure blade with the water-soluble core material. After the pressing of the water-soluble sandwich core is completed, embed the water-soluble sandwich core into the mold of the ceramic core of the complex multi-layer wall structure blade, and press the overall green body of the ceramic core of the complex multi-layer wall structure blade with the ceramic material;

[0014] Step 3: Put the green body of the ceramic core of the complex multi-layer wall structure blade containing the water-soluble sandwich core into acidified water to remove the water-soluble sandwich core. After the removal of the water-soluble sandwich core is completed, the green body of the ceramic core of the complex multi-layer wall structure blade can be obtained;

[0015] Step 4: Fill the interlayer of the green body of the ceramic core of the complex multi-layer wall structure blade with a filler, and at the same time bury the green body of the ceramic core of the complex multi-layer wall structure blade in the filler for sintering. After the sintering is completed, the sintered ceramic core of the complex multi-layer wall structure blade can be obtained;

[0016] Step 5: Press a green body of the ceramic core for the hollow flange structure blade with the ceramic material. After the pressing is completed, bury the green body of the ceramic core for the hollow flange structure blade in the filler for sintering. After the sintering is completed, the sintered ceramic core for the hollow flange structure blade can be obtained;

[0017] Step 6: Combine and form the ceramic core of the sintered complex multi-layer wall structure blade and the ceramic core of the sintered hollow flange structure blade in a mortise and tenon manner. That is, first evenly coat a layer of adhesive on the outer walls of the elliptical hemisphere structure and the cylindrical structure in the T-shaped structure, then align the groove of the ceramic core of the hollow flange structure blade with the elliptical hemisphere structure and the cylindrical structure, and at the same time insert the elliptical hemisphere structure and the cylindrical structure coated with adhesive into the groove. Finally, use a grinding tool to remove the excess adhesive extruded and clean it. After cleaning, dry it to obtain the ceramic core for the complex multi-layer wall and hollow flange structure blade.

[0018] Preferably, in Step 1, the mass percentages of the various substances in the water-soluble core material are as follows: spherical quartz glass powder 2-8wt%, irregular quartz glass powder 5-10wt%, methyl cellulose 10-30wt%, talcum powder 3-8wt%, polyvinyl alcohol 10-20wt%, polypropylene 10-20wt%, carbon black 3-8wt%, ammonium bicarbonate 10-30wt%, sodium chloride 10-30wt%, ammonium chloride 2-5wt%, lecithin 0.2-1wt%. The sum of the mass percentages of the above substances is 100wt%.

[0019] Put the above substances into a blender and mix evenly to obtain the water-soluble core material. The stirring temperature is 100-120°C, the stirring time is 2-2.5h, and the stirring speed is 1000-1500r / min.

[0020] In any of the above preferred solutions, in Step 2, at least one water-soluble sandwich core is provided in the ceramic core for the complex multi-layer wall structure blade. The water-soluble sandwich core is formed by injection molding. The pressing temperature is 50-60°C, the injection speed is 30-40cc / s, and the holding pressure time is 5-10s. The green body of the ceramic core for the complex multi-layer wall structure blade is formed by injection molding. The pressing temperature is 50-60°C, the pressure is 70-80bar, and the holding pressure time is 30-60s.

[0021] Preferably, in any of the above solutions, in step three, the method for removing the water-soluble core is as follows: First, soak the green ceramic core of the complex multi-layer wall structure blade containing the water-soluble core in acidified water to dissolve the water-soluble core in the interlayer. The soaking time is 10 - 40 min, and the concentration of citric acid in the acidified water is 8 - 15 mg / L. Secondly, use a pressurized nozzle to clean the interlayer to further remove the residual water-soluble core in the interlayer. The water flow diameter does not exceed 2 mm, and the pressure is 68 - 200 KPa. Then, use water flow to rinse the surface and interlayer of the green ceramic core of the complex multi-layer wall structure blade clean. The flow rate of the water flow is 100 - 150 cc / s. Finally, leave the green ceramic core of the complex multi-layer wall structure blade to air dry. The drying temperature is 20 - 25 °C, the wind speed is 3 - 5 m / s, and the drying time is 2 - 5 h.

[0022] Preferably, in any of the above solutions, in step four, the sintering temperature of the green ceramic core of the complex multi-layer wall structure blade is 1150 - 1200 °C, and the sintering time is 5 - 8 h.

[0023] Preferably, in any of the above solutions, in step five, the green ceramic core of the blade with a hollow flange structure is molded by an injection molding process. The molding temperature is 55 - 80 °C, the pressure is 70 - 80 bar, and the holding pressure time is 10 - 20 s. The sintering temperature of the green ceramic core of the blade with a hollow flange structure is 1150 - 1200 °C, and the sintering time is 5 - 8 h.

[0024] Preferably, in any of the above solutions, in step six, use a grinding tool to remove the extruded excess adhesive and clean it. After cleaning, dry it. The drying temperature is 110 - 130 °C, and the drying time is 8 - 12 min.

[0025] For the mixer, injection molding equipment, etc. used in the present invention, existing equipment can be selected without special requirements for the model. The L-shaped structure and T-shaped structure are used to form the blade cooling cavity, which can greatly improve the cooling effect of the blade. At least one water-soluble core is arranged in the green ceramic core of the complex multi-layer wall structure blade. The water-soluble core is in an irregular long strip shape, and different water-soluble cores have different sizes and details. The prepared water-soluble core material has the characteristics of high strength and high softening point. The strength is not less than 20 MPa, and it can withstand a relatively high temperature at the same time. When pressing ceramic materials outside the water-soluble core by an injection molding process, the temperature of the flowing ceramic material is relatively high, not less than 80 °C. The water-soluble core prepared with the water-soluble core material of the present invention will not be melted and will not have defects such as cracking. The fillers used are materials such as kaolin and alumina.

[0026] In the present invention, a layer of adhesive is evenly coated on the outer walls of the elliptical hemispherical structure and the cylindrical structure in the T-shaped structure. After coating the adhesive, the elliptical hemispherical structure and the cylindrical structure are inserted into the groove of the ceramic core for the blade with a hollow flange structure, and then the extruded adhesive is cleaned up. This design can make most of the bonding areas inside the groove, reducing the casting weld caused by the secondary shrinkage of the ceramic core during the casting process; at the same time, the combination of the elliptical hemispherical structure and the cylindrical structure is adopted at the combination part, which can improve the success rate of the combined connection and the dimensional stability of the ceramic core after sintering.

[0027] The ceramic core for the blade with a complex multi-layer wall and a hollow flange structure and the preparation method thereof according to the present invention can meet the requirements of precision casting of the hollow turbine blade with a "shock / film cooling" complex multi-layer wall and a hollow flange structure. Among them, the ceramic core for the blade with a complex multi-layer wall structure is formed by the water-soluble core method, and the ceramic core for the blade with a hollow flange structure is combined and formed with the cylindrical structure and the elliptical hemispherical structure in the T-shaped structure by the mortise and tenon method. The present invention can prepare a complete ceramic core for the blade with a complex multi-layer wall and a hollow flange structure, and the structure of the ceramic core is complete, the size is accurate, and the stability is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. is a schematic structural diagram of a ceramic core for a blade with a complex multi-layer wall and a hollow flange structure prepared according to a preferred embodiment of the ceramic core for a blade with a complex multi-layer wall and a hollow flange structure and the preparation method thereof according to the present invention;

[0029] Figure 2 For Figure 1 A cross-sectional schematic diagram of the complex multi-layer wall core structure in the shown embodiment;

[0030] Figure 3 For Figure 1 A schematic diagram of the T-shaped structure in the shown embodiment;

[0031] Figure 4 For Figure 1 A schematic diagram of the ceramic core for a blade with a hollow flange structure in the shown embodiment;

[0032] Figure 5 For Figure 1 A schematic diagram of the combination of the ceramic core for a blade with a hollow flange structure and the elliptical hemispherical structure and the cylindrical structure in the T-shaped structure by the mortise and tenon method in the shown embodiment.

[0033] Description of the reference numerals in the drawings:

[0034] 1 - Ceramic core for blade with complex multi - layer wall structure, 11 - Complex multi - layer wall core structure, 12 - L - shaped structure, 13 - T - shaped structure, 131 - Cuboid structure, 132 - Cylindrical structure, 133 - Elliptical hemisphere structure;

[0035] 2 - Ceramic core for blade with hollow flange structure, 21 - Groove;

[0036] 3 - Adhesive, 4 - Blade, 5 - Double - layer wall, 6 - Water - soluble sandwich core;

[0037] A - Distance from the vertex of the groove to the top surface of the ceramic core for blade with hollow flange structure;

[0038] B - Distance from the vertex of the groove to the bottom surface of the ceramic core for blade with hollow flange structure. Detailed implementation mode

[0039] In order to further understand the content of the present invention, the present invention will be elaborated in detail below in combination with specific embodiments.

[0040] Embodiment 1:

[0041] As Figure 1 、 Figures 3 - 5 shown, according to a preferred embodiment of the ceramic core for blades with complex multi - layer wall and hollow flange structures of the present invention, it includes a ceramic core 1 for blades with complex multi - layer wall structure and a ceramic core 2 for blades with hollow flange structure, both of which are integrally formed structures; the ceramic core 1 for blades with complex multi - layer wall structure includes a complex multi - layer wall core structure 11, an L - shaped structure 12 and a T - shaped structure 13. One end of the L - shaped structure 12 is fixedly connected to the complex multi - layer wall core structure 11, the other end of the L - shaped structure 12 is fixedly connected to one end of the T - shaped structure 13, and the other end of the T - shaped structure 13 is combined and connected to the ceramic core 2 for blades with hollow flange structure in a mortise - and - tenon manner; the ceramic core 2 for blades with hollow flange structure, the L - shaped structure 12 and the T - shaped structure 13 form a hollow flange core structure.

[0042] The cross - section of the L - shaped structure 12 is circular with a diameter of 2 mm; the T - shaped structure 13 is composed of a cuboid structure 131, a cylindrical structure 132 and an elliptical hemisphere structure 133 from bottom to top in sequence; the cuboid structure 131 has a length of 9 mm, a width of 9 mm and a height of 7 mm; the cylindrical structure 132 has a height of 7 mm, the cross - section of the cylindrical structure 132 is elliptical, the short side length of the ellipse is 4 mm, and the long side length is 1.5 times the short side length, that is, the long side length is 6 mm; the elliptical hemisphere structure 133 is a structure cut along the central plane where the long side of the ellipse is located, the short side length of the elliptical hemisphere structure 133 is 4 mm, and the long side length is 1.5 times the short side length, that is, the long side length is 6 mm.

[0043] The ceramic core 2 for the hollow flange structure blade is in a cuboid structure. The length of the cuboid structure is 16 mm, the width is 16 mm, and the height is 13 mm. A groove 21 is opened at the center position of the bottom of the ceramic core 2 for the hollow flange structure blade. The groove 21 is combined and connected with the cylindrical structure 132 and the elliptical hemisphere structure 133 in the T-shaped structure 13 in a mortise and tenon manner. And a 0.8-mm gap is evenly formed between the inner wall of the groove 21 and the outer walls of the cylindrical structure 132 and the elliptical hemisphere structure 133; The outer walls of the cylindrical structure 132 and the elliptical hemisphere structure 133 are evenly coated with an adhesive 3 with a thickness of 0.8 mm. The distance A from the vertex of the groove to the top surface of the ceramic core for the hollow flange structure blade is 5 mm, and the distance B from the vertex of the groove to the bottom surface of the ceramic core for the hollow flange structure blade is 8 mm.

[0044] The cross-sectional schematic diagram of the complex multi-layer wall core structure 11 is as Figure 2 shown. The part shown with hatching in the figure is the traditional double-layer wall 5 and the water-soluble sandwich 6 of the present embodiment, and the rest is the blade 4. The water-soluble sandwich 6 of the present embodiment is in an irregular strip structure. The strip structure represents a complex multi-layer wall structure, and each strip structure is formed by connecting two channels in a group of double-layer walls. The complex multi-layer wall core structure of the present embodiment includes both a double-layer wall structure and a complex multi-layer wall structure.

[0045] The present embodiment also provides a preparation method for a ceramic core for a complex multi-layer wall and a hollow flange structure blade, which is used to prepare the above-mentioned ceramic core for a complex multi-layer wall and a hollow flange structure blade, and includes the following steps in sequence:

[0046] Step 1: Prepare a water-soluble core material according to the design requirements;

[0047] Step 2: Use the water-soluble core material to press the water-soluble sandwich of the ceramic core for the complex multi-layer wall structure blade. After the pressing of the water-soluble sandwich is completed, embed the water-soluble sandwich into the mold of the ceramic core for the complex multi-layer wall structure blade, and use ceramic materials to press the whole green body of the ceramic core for the complex multi-layer wall structure blade;

[0048] Step 3: Put the green body of the ceramic core for the complex multi-layer wall structure blade containing the water-soluble sandwich into acidified water to remove the water-soluble sandwich. After the removal of the water-soluble sandwich is completed, the green body of the ceramic core for the complex multi-layer wall structure blade can be obtained;

[0049] Step 4: Filling the interlayer of the ceramic core blank for the blade with a complex multi-layer wall structure with a filler, and embedding the ceramic core blank for the blade with a complex multi-layer wall structure in the filler for sintering. After the sintering is completed, a sintered ceramic core for the blade with a complex multi-layer wall structure can be obtained;

[0050] Step 5: Using ceramic material to press the ceramic core blank for the hollow edge plate structure blade, after the pressing is completed, the ceramic core blank for the hollow edge plate structure blade is embedded in filler and sintered, after the sintering is completed, a sintered ceramic core for the hollow edge plate structure blade is obtained;

[0051] Step six: Combine and mold the sintered ceramic core for blades with complex multi-layer wall structure and the sintered ceramic core for blades with hollow edge plate structure in a mortise and tenon manner, that is, first evenly apply a layer of adhesive on the outer wall of the elliptical hemispherical structure and the outer wall of the cylindrical structure in the T-shaped structure, and then align the groove of the ceramic core for blades with the elliptical hemispherical structure and the cylindrical structure, and insert the elliptical hemispherical structure and the cylindrical structure coated with adhesive into the groove at the same time, and finally use a grinding tool to remove the excess adhesive squeezed out and clean it, and then dry it after cleaning to obtain the ceramic core for blades with complex multi-layer wall and hollow edge plate structure.

[0052] In step 1, the weight percentages of the substances in the water-soluble core material are as follows: 5 wt% spherical quartz glass powder, 7 wt% irregular quartz glass powder, 15 wt% methyl cellulose, 5 wt% talc, 15 wt% polyvinyl alcohol, 15 wt% polypropylene, 4 wt% carbon black, 15 wt% ammonium bicarbonate, 15 wt% sodium chloride, 3 wt% ammonium chloride, and 1 wt% lecithin, with the total weight percentages being 100 wt%. The water-soluble core material is obtained by mixing the above substances in a blender at a temperature of 110° C., a time of 2 hours, and a speed of 1200 r / min.

[0053] In step 2, two water-soluble cores are set in the ceramic core for the complex multi-layer wall structure blade, and the water-soluble core is pressed and molded by injection molding process, with a pressing temperature of 55°C, an injection speed of 35cc / s, and a holding time of 8s; the ceramic core blank for the complex multi-layer wall structure blade is pressed and molded by injection molding process, with a pressing temperature of 55°C, a pressure of 75bar, and a holding time of 45s.

[0054] In Step 3, the method for removing the water-soluble core is as follows: First, soak the complex multi-layer wall structure blade with the water-soluble core in acidified water using a green ceramic core for 30 minutes. The concentration of citric acid in the acidified water is 12 mg / L. Second, use a pressure spray head to clean the interlayer to further remove the residual water-soluble core in the interlayer. The water flow diameter is 2 mm and the pressure is 120 KPa. Third, use water flow to rinse the surface and interlayer of the complex multi-layer wall structure blade with the green ceramic core until clean. The water flow rate is 120 cc / s. Finally, leave the complex multi-layer wall structure blade with the green ceramic core to air dry at a temperature of 22°C, a wind speed of 4 m / s, and for a duration of 4 hours.

[0055] In Step 4, the sintering temperature of the complex multi-layer wall structure blade with the green ceramic core is 1180°C and the sintering time is 7 hours.

[0056] In Step 5, the hollow flange structure blade with the green ceramic core is molded by injection molding at a temperature of 70°C, a pressure of 75 bar, and a holding pressure time of 15 s. The sintering temperature of the hollow flange structure blade with the green ceramic core is 1180°C and the sintering time is 7 hours.

[0057] In Step 6, use a grinding tool to remove the extruded excess bonding glue and clean it. After cleaning, dry it at a temperature of 120°C for 10 minutes.

[0058] For this embodiment, existing equipment such as mixers and injection molding equipment can be selected without special requirements for the model. The L-shaped structure and T-shaped structure are used to form the blade cooling cavity, which can significantly improve the cooling effect of the blade. Two water-soluble cores are provided in the complex multi-layer wall structure blade with the green ceramic core. The two water-soluble cores are in the shape of irregular long strips with different sizes and details. The prepared water-soluble core material has the characteristics of high strength and high softening point, with a strength not lower than 20 MPa, and can withstand relatively high temperatures. When pressing ceramic materials outside the water-soluble core using the injection molding process, the temperature of the flowing ceramic material is relatively high, not lower than 80°C. The water-soluble core prepared with the water-soluble core material of the present invention will not be melted and will not have defects such as cracking. The fillers used are materials such as kaolin and alumina.

[0059] In this embodiment, a layer of bonding glue is evenly coated on the outer walls of the elliptical hemisphere structure and the cylindrical structure in the T-shaped structure. After coating the bonding glue, the elliptical hemisphere structure and the cylindrical structure are inserted into the groove of the ceramic core for the blade of the hollow flange structure, and then the extruded bonding glue is cleaned up. This design can make most of the bonding areas inside the groove, reducing the casting weld caused by the secondary shrinkage of the ceramic core during the casting process. At the same time, the combination of the elliptical hemisphere structure and the cylindrical structure at the combined part can improve the success rate of the combined connection and the dimensional stability of the ceramic core after sintering.

[0060] The ceramic core for the blade with a complex multi-layer wall and a hollow flange structure and the preparation method thereof in this embodiment can meet the requirements of precision casting of the hollow turbine blade with a "shock / film cooling" complex multi-layer wall and a hollow flange structure. Among them, the ceramic core for the blade with a complex multi-layer wall structure is formed by the water-soluble core method, and the ceramic core for the blade with a hollow flange structure is combined and formed with the cylindrical structure and the elliptical hemisphere structure in the T-shaped structure by the mortise and tenon method. This embodiment can prepare a complete ceramic core for the blade with a complex multi-layer wall and a hollow flange structure, and the structure of the ceramic core is complete, the size is accurate, and the stability is high.

[0061] Embodiment 2:

[0062] According to another preferred embodiment of the ceramic core for the blade with a complex multi-layer wall and a hollow flange structure and the preparation method thereof of the present invention, the structure of the ceramic core, the connection relationship between its various parts, the preparation method of the ceramic core, the equipment used, the technical principle and the beneficial effects, etc. are basically the same as those in Embodiment 1, except that:

[0063] The cross-section of the L-shaped structure is circular, and its diameter is 3 mm; the T-shaped structure is successively composed of a cuboid structure, a cylindrical structure and an elliptical hemisphere structure from bottom to top; the length of the cuboid structure is 10 mm, the width is 10 mm, and the height is 8 mm; the height of the cylindrical structure is 8 mm, the cross-section of the cylindrical structure is elliptical, the short side length of the ellipse is 6 mm, and the long side length is 1.2 times the short side length, that is, the long side length is 7.2 mm; the elliptical hemisphere structure is a structure cut along the central plane where the long side of the ellipse is located, the short side length of the elliptical hemisphere is 6 mm, and the long side length is 1.2 times the short side length, that is, the long side length is 7.2 mm.

[0064] The ceramic core for the blade with a hollow flange structure is in a cuboid structure. The length of the cuboid structure is 18 mm, the width is 18 mm, and the height is 13 mm. A groove is opened at the center of the bottom of the ceramic core for the blade with a hollow flange structure. The groove is combined and connected with the cylindrical structure and the elliptical hemisphere structure in the T-shaped structure in a mortise and tenon manner, and a 1-mm gap is evenly formed between the inner wall of the groove and the outer walls of the cylindrical structure and the elliptical hemisphere structure; a bonding adhesive with a thickness of 1 mm is evenly coated on the outer walls of the cylindrical structure and the elliptical hemisphere structure. The distance from the vertex of the groove to the top surface of the ceramic core for the blade with a hollow flange structure is 5 mm, and the distance from the vertex of the groove to the bottom surface of the ceramic core for the blade with a hollow flange structure is 8 mm.

[0065] In step one, the mass percentages of the substances in the water-soluble core material in the water-soluble core material are as follows: spherical quartz glass powder 8 wt%, special-shaped quartz glass powder 5 wt%, methyl cellulose 10 wt%, talc powder 8 wt%, polyvinyl alcohol 10 wt%, polypropylene 10 wt%, carbon black 3 wt%, ammonium bicarbonate 30 wt%, sodium chloride 10 wt%, ammonium chloride 5 wt%, lecithin 1 wt%. The sum of the mass percentages of the above substances is 100 wt%. Put the above substances into a blender and mix evenly to obtain the water-soluble core material. The stirring temperature is 120 °C, the stirring time is 2.5 h, and the stirring speed is 1000 r / min.

[0066] In step two, two water-soluble sandwich cores are arranged in the ceramic core for the blade with a complex multi-layer wall structure. The water-soluble sandwich cores are formed by injection molding process. The pressing temperature is 60 °C, the injection speed is 40 cc / s, and the holding pressure time is 5 s; the green body of the ceramic core for the blade with a complex multi-layer wall structure is formed by injection molding process. The pressing temperature is 60 °C, the pressure is 80 bar, and the holding pressure time is 30 s.

[0067] In step three, the method for removing the water-soluble sandwich core is as follows: First, put the green body of the ceramic core for the blade with a complex multi-layer wall structure containing the water-soluble sandwich core into acidified water and soak it to dissolve the water-soluble sandwich core in the sandwich layer. The soaking time is 40 min, and the concentration of citric acid in the acidified water is 15 mg / L; secondly, use a pressurized nozzle to wash the sandwich layer to further remove the residual water-soluble sandwich core in the sandwich layer. The water flow diameter is 2 mm, and the pressure is 200 KPa; then use water flow to wash the surface and the sandwich layer of the green body of the ceramic core for the blade with a complex multi-layer wall structure clean. The flow rate of the water flow is 150 cc / s; finally, let the green body of the ceramic core for the blade with a complex multi-layer wall structure stand and dry. The drying temperature is 25 °C, the wind speed is 5 m / s, and the drying time is 2 h.

[0068] In Step 4, the sintering temperature of the ceramic core green body for the blade with a complex multi-layer wall structure is 1200 °C, and the sintering time is 5 h.

[0069] In Step 5, the ceramic core green body for the blade with a hollow flange structure is molded by an injection molding process. The pressing temperature is 80 °C, the pressure is 80 bar, and the holding pressure time is 10 s. The sintering temperature of the ceramic core green body for the blade with a hollow flange structure is 1200 °C, and the sintering time is 5 h.

[0070] In Step 6, a grinding tool is used to remove the excess bonding glue extruded and clean it. After cleaning, it is dried. The drying temperature is 130 °C, and the drying time is 8 min.

[0071] Example 3:

[0072] According to another preferred embodiment of the ceramic core for blades with a complex multi-layer wall and hollow flange structure and its preparation method of the present invention, the structure of the ceramic core, the connection relationship between its various parts, the preparation method of the ceramic core, the equipment used, the technical principle, and the beneficial effects are basically the same as those in Example 1, except that:

[0073] The cross-section of the L-shaped structure is circular, and its diameter is 2 mm. The T-shaped structure consists of a cuboid structure, a cylinder structure, and an elliptical hemisphere structure from bottom to top. The cuboid structure has a length of 8 mm, a width of 8 mm, and a height of 5 mm. The height of the cylinder structure is 5 mm. The cross-section of the cylinder structure is elliptical, the short side length of the ellipse is 4 mm, and the long side length is 1.5 times the short side length, that is, the long side length is 6 mm. The elliptical hemisphere structure is a structure cut along the central plane where the long side of the ellipse is located. The short side length of the elliptical hemisphere is 4 mm, and the long side length is 1.5 times the short side length, that is, the long side length is 6 mm.

[0074] The ceramic core for the blade with a hollow flange structure is a cuboid structure. The cuboid structure has a length of 15 mm, a width of 15 mm, and a height of 8 mm. A groove is opened at the center position of the bottom of the ceramic core for the blade with a hollow flange structure. The groove is combined and connected with the cylinder structure and the elliptical hemisphere structure in the T-shaped structure in a tenon-mortise manner, and a 0.5-mm gap is evenly formed between the inner wall of the groove and the outer walls of the cylinder structure and the elliptical hemisphere structure. The outer walls of the cylinder structure and the elliptical hemisphere structure are evenly coated with a bonding glue with a thickness of 0.5 mm. The distance from the vertex of the groove to the top surface of the ceramic core for the blade with a hollow flange structure is 3 mm, and the distance from the vertex of the groove to the bottom surface of the ceramic core for the blade with a hollow flange structure is 5 mm.

[0075] In Step 1, the mass percentages of the substances in the water-soluble core material are as follows: spherical quartz glass powder 2 wt%, irregular quartz glass powder 8 wt%, methylcellulose 20 wt%, talcum powder 3 wt%, polyvinyl alcohol 18 wt%, polypropylene 18 wt%, carbon black 6 wt%, ammonium bicarbonate 10 wt%, sodium chloride 12 wt%, ammonium chloride 2 wt%, and lecithin 1 wt%. The sum of the mass percentages of the above substances is 100 wt%. Put the above substances into a blender and mix evenly to obtain the water-soluble core material. The stirring temperature is 100 °C, the stirring time is 2.5 h, and the stirring speed is 1500 r / min.

[0076] In Step 2, two water-soluble sandwich cores are provided in the ceramic core for the complex multi-layer wall structure blade. The water-soluble sandwich cores are formed by injection molding. The pressing temperature is 50 °C, the injection speed is 30 cc / s, and the holding pressure time is 10 s. The green body of the ceramic core for the complex multi-layer wall structure blade is formed by injection molding. The pressing temperature is 50 °C, the pressure is 70 bar, and the holding pressure time is 60 s.

[0077] In Step 3, the method for removing the water-soluble sandwich core is as follows: First, put the green body of the ceramic core for the complex multi-layer wall structure blade containing the water-soluble sandwich core into acidified water and soak it to dissolve the water-soluble sandwich core in the interlayer. The soaking time is 10 min, and the concentration of citric acid in the acidified water is 8 mg / L. Secondly, use a pressurized nozzle to wash the interlayer to further remove the residual water-soluble sandwich core in the interlayer. The water flow diameter is 2 mm, and the pressure is 68 KPa. Then, use water flow to wash the surface and the interlayer of the green body of the ceramic core for the complex multi-layer wall structure blade clean. The water flow rate is 100 cc / s. Finally, leave the green body of the ceramic core for the complex multi-layer wall structure blade to stand and dry. The drying temperature is 20 °C, the wind speed is 3 m / s, and the drying time is 5 h.

[0078] In Step 4, the sintering temperature of the green body of the ceramic core for the complex multi-layer wall structure blade is 1150 °C, and the sintering time is 8 h.

[0079] In Step 5, the green body of the ceramic core for the blade with a hollow flange structure is formed by injection molding. The pressing temperature is 55 °C, the pressure is 70 bar, and the holding pressure time is 20 s. The sintering temperature of the green body of the ceramic core for the blade with a hollow flange structure is 1150 °C, and the sintering time is 8 h.

[0080] In Step 6, use a grinding tool to remove the extruded excess adhesive and clean it. After cleaning, dry it. The drying temperature is 110 °C, and the drying time is 12 min.

[0081] Special Note: In the technical solution of the present invention, many parameters are involved. It is necessary to comprehensively consider the synergistic effects among various parameters to obtain the beneficial effects and remarkable progress of the present invention. Moreover, the value ranges of various parameters in the technical solution are obtained through a large number of experiments. For each parameter and the combination of various parameters, the inventor has recorded a large amount of experimental data. Due to space limitations, the specific experimental data are not disclosed herein.

[0082] Those skilled in the art can easily understand that the ceramic core for blades with a complex multi-layer wall and hollow flange structure and the preparation method thereof of the present invention include any combination of the above-mentioned invention content, specific implementation manners of the present invention specification, and various parts shown in the drawings. Due to space limitations and to make the specification concise, the various solutions formed by these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A ceramic core for a blade with a complex multi-layer wall and hollow flange structure, characterized in that: It includes a ceramic core for a blade with a complex multi-layer wall structure and a ceramic core for a blade with a hollow flange structure, both of which are integrally formed structures; the ceramic core for the blade with a complex multi-layer wall structure includes a complex multi-layer wall core structure, an L-shaped structure, and a T-shaped structure. One end of the L-shaped structure is fixedly connected to the complex multi-layer wall core structure, the other end of the L-shaped structure is fixedly connected to one end of the T-shaped structure, and the other end of the T-shaped structure is combined and connected to the ceramic core for the blade with a hollow flange structure in a tenon-mortise manner; the ceramic core for the blade with a hollow flange structure, the L-shaped structure, and the T-shaped structure form a hollow flange core structure.

2. The ceramic core for a blade with a complex multi-layer wall and hollow flange structure according to claim 1, wherein: The cross-section of the L-shaped structure is circular, with a diameter of 2-3 mm; the T-shaped structure is composed of a cuboid structure, a cylinder structure, and an elliptical hemisphere structure from bottom to top in sequence; the length of the cuboid structure is 8-10 mm, the width is 8-10 mm, and the height is 5-8 mm; the height of the cylinder structure is 5-8 mm, the cross-section of the cylinder structure is elliptical, the short side length of the ellipse is 4-6 mm, and the long side length is 1.2-1.5 times the short side length; the elliptical hemisphere structure is a structure cut along the central plane where the long side of the ellipse is located, and the short side length of the elliptical hemisphere structure is 4-6 mm, and the long side length is 1.2-1.5 times the short side length.

3. The ceramic core for a blade with a complex multi-layer wall and hollow flange structure according to claim 2, characterized in that: The ceramic core for the blade with a hollow flange structure is a cuboid structure, with a length of 15-18 mm, a width of 15-18 mm, and a height of 8-13 mm.

4. The ceramic core for the blade with a complex multi-layer wall and hollow flange structure according to claim 3, wherein: A groove is opened at the center position of the bottom of the ceramic core for the blade with a hollow flange structure. The groove is combined and connected to the cylinder structure and the elliptical hemisphere structure in the T-shaped structure in a tenon-mortise manner, and a gap of 0.5-1 mm is evenly formed between the inner wall of the groove and the outer walls of the cylinder structure and the elliptical hemisphere structure; a bonding adhesive with a thickness of 0.5-1 mm is evenly coated on the outer walls of the cylinder structure and the elliptical hemisphere structure.

5. The ceramic core for a blade with a complex multi-layer wall and hollow flange structure according to claim 4, characterized in that: The distance from the vertex of the groove to the top surface of the ceramic core for the blade with a hollow flange structure is 3-5 mm, and the distance from the vertex of the groove to the bottom surface of the ceramic core for the blade with a hollow flange structure is 5-8 mm.

6. A preparation method of a ceramic core for a blade with a complex multi-layer wall and hollow rib structure, characterized in that: For preparing the ceramic core for the blade with a complex multi-layer wall and a hollow flange structure according to any one of claims 1-5, the following steps are included in sequence, Step 1: Prepare a water-soluble core material according to the design requirements; Step 2: Press the water-soluble sandwich core of the ceramic core for the blade with a complex multi-layer wall structure using the water-soluble core material. After the pressing of the water-soluble sandwich core is completed, embed the water-soluble sandwich core into the mold of the ceramic core for the blade with a complex multi-layer wall structure, and press the overall green body of the ceramic core for the blade with a complex multi-layer wall structure using ceramic materials; Step 3: Put the green body of the ceramic core for the blade with a complex multi-layer wall structure containing the water-soluble sandwich core into acidified water to remove the water-soluble sandwich core. After the removal of the water-soluble sandwich core is completed, the green body of the ceramic core for the blade with a complex multi-layer wall structure can be obtained; Step 4: Filling the interlayer of the ceramic core blank for the blade with a complex multi-layer wall structure with a filler, and embedding the ceramic core blank for the blade with a complex multi-layer wall structure in the filler for sintering. After the sintering is completed, a sintered ceramic core for the blade with a complex multi-layer wall structure can be obtained; Step 5: Using ceramic material to press the ceramic core blank for the hollow edge plate structure blade, after the pressing is completed, the ceramic core blank for the hollow edge plate structure blade is embedded in filler and sintered, after the sintering is completed, a sintered ceramic core for the hollow edge plate structure blade is obtained; Step six: Combine and mold the sintered ceramic core for blades with complex multi-layer wall structure and the sintered ceramic core for blades with hollow edge plate structure in a mortise and tenon manner, that is, first evenly apply a layer of adhesive on the outer wall of the elliptical hemispherical structure and the outer wall of the cylindrical structure in the T-shaped structure, and then align the groove of the ceramic core for blades with the elliptical hemispherical structure and the cylindrical structure, and insert the elliptical hemispherical structure and the cylindrical structure coated with adhesive into the groove at the same time, and finally use a grinding tool to remove the excess adhesive squeezed out and clean it, and then dry it after cleaning to obtain the ceramic core for blades with complex multi-layer wall and hollow edge plate structure.

7. The preparation method of the ceramic core for the blade with a complex multi-layer wall and hollow flange structure according to claim 6, characterized in that: In step 1, the mass percentage of each substance in the water-soluble core material is 2-8wt% of spherical quartz glass powder, 5-10wt% of special-shaped quartz glass powder, 10-30wt% of methyl cellulose, 3-8wt% of talc, 10-20wt% of polyvinyl alcohol, 10-20wt% of polypropylene, 3-8wt% of carbon black, 10-30wt% of ammonium bicarbonate, 10-30wt% of sodium chloride, 2-5wt% of ammonium chloride, and 0.2-1wt% of lecithin, and the total mass percentage of the above substances is 100wt%; The above substances are put into a blender and mixed evenly to obtain a water-soluble core material. The stirring temperature is 100-120°C, the stirring time is 2-2.5h, and the stirring speed is 1000-1500r / min.

8. The preparation method of the ceramic core for the blade with a complex multi-layer wall and hollow flange structure according to claim 7, characterized in that: In step 2, at least one water-soluble core is provided in the ceramic core for the complex multi-layer wall structure blade, and the water-soluble core is pressed and molded by an injection molding process, with a pressing temperature of 50-60°C, an injection speed of 30-40cc / s, and a holding time of 5-10s; the ceramic core blank for the complex multi-layer wall structure blade is pressed and molded by an injection molding process, with a pressing temperature of 50-60°C, a pressure of 70-80bar, and a holding time of 30-60s.

9. The preparation method of the ceramic core for the blade with a complex multi-layer wall and hollow flange structure according to claim 8, wherein: In Step 3, the method for removing the water-soluble core is as follows: First, immerse the green ceramic core of the complex multi-layer wall structure blade containing the water-soluble core in acidified water for 10 - 40 minutes to dissolve the water-soluble core in the interlayer. The concentration of citric acid in the acidified water is 8 - 15 mg / L. Second, use a pressure spray head to clean the interlayer to further remove the residual water-soluble core in the interlayer. The water flow diameter does not exceed 2 mm, and the pressure is 68 - 200 KPa. Then, use water flow to rinse the surface and interlayer of the green ceramic core of the complex multi-layer wall structure blade clean. The water flow rate is 100 - 150 cc / s. Finally, leave the green ceramic core of the complex multi-layer wall structure blade to air dry. The air drying temperature is 20 - 25 °C, the wind speed is 3 - 5 m / s, and the air drying time is 2 - 5 hours.

10. The preparation method of the ceramic core for the blade with a complex multi-layer wall and hollow flange structure according to claim 9, characterized in that: In Step 4, the sintering temperature of the green ceramic core of the complex multi-layer wall structure blade is 1150 - 1200 °C, and the sintering time is 5 - 8 hours. In Step 5, the green ceramic core of the blade with a hollow flange structure is molded by an injection molding process. The molding temperature is 55 - 80 °C, the pressure is 70 - 80 bar, and the holding pressure time is 10 - 20 s. The sintering temperature of the green ceramic core of the blade with a hollow flange structure is 1150 - 1200 °C, and the sintering time is 5 - 8 hours. In Step 6, use a grinding tool to remove and clean the extruded excess adhesive. After cleaning, dry it. The drying temperature is 110 - 130 °C, and the drying time is 8 - 12 minutes.

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