Preparation method of alumina-based ceramic core and alumina-based ceramic core

Abstract

The invention relates to the technical field of ceramic additive manufacturing, and discloses a preparation method of an alumina-based ceramic core and the alumina-based ceramic core, the preparation method comprises the following steps: adding mixed powder of PMMA microspheres and alumina ceramic powder into a photosensitive resin premixed solution, and carrying out ball milling to obtain alumina-based ceramic slurry; adding the alumina-based ceramic slurry into a trough of a 3D printer, and printing under the irradiation of a light source to obtain an alumina-based ceramic core biscuit; and degreasing and sintering the alumina-based ceramic core biscuit to obtain the alumina-based ceramic core. Therefore, according to the preparation method, the process cost can be effectively reduced, the production efficiency can be improved, and meanwhile, the porosity of the aluminum oxide-based ceramic core can be improved, so that the depoling efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic additive manufacturing, and relates to a method for preparing an alumina-based ceramic core and an alumina-based ceramic core. Background Art

[0002] Ceramic cores can form cavities for castings with complex shapes or that are difficult to form. At present, they are often used to form the hollow inner cavity structure of hollow blades of aircraft turbine engines. In this way, the hollow blades of turbine engines formed have higher cooling efficiency and can withstand higher operating temperatures, thereby effectively improving the thrust-to-weight ratio of aircraft engines. At present, alumina ceramics are usually used to make alumina-based ceramic cores. Alumina ceramics have high strength, high temperature resistance, corrosion resistance, and good insulation.

[0003] When an alumina-based ceramic core is used for the hollow inner cavity structure of a hollow blade, it needs to have a higher porosity to improve its core removal efficiency. For example, in the related art, starch is used as a pore-forming agent to adjust the porosity, and another example is to adjust the porosity by mixing powders of different particle sizes and proportions.

[0004] In the process of implementing the embodiments of the present disclosure, it is found that there are at least the following problems in the related art:

[0005] The above method can improve the porosity to a certain extent, but the molding process is costly and has a long cycle. In addition, the obtained porosity may also affect the core removal efficiency.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present application, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0007] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical components or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

[0008] The embodiments of the present disclosure provide a method for preparing an alumina-based ceramic core and an alumina-based ceramic core, which can effectively reduce process costs and improve production efficiency, while also increasing the porosity of the alumina-based ceramic core, thereby improving core removal efficiency.

[0009] In some embodiments, the method for preparing the alumina-based ceramic core comprises the following steps:

[0010] The mixed powder of PMMA microspheres and alumina ceramic powder is added into the photosensitive resin premixed liquid, and the alumina-based ceramic slurry is obtained by ball milling;

[0011] Adding alumina-based ceramic slurry into a material tank of a 3D printer and printing under light source to obtain an alumina-based ceramic core blank;

[0012] The alumina-based ceramic core blank is degreased and sintered to obtain the alumina-based ceramic core.

[0013] Optionally, the volume percentage of the mixed powder in the alumina-based ceramic slurry is 38% to 82%, and the volume percentage of the photosensitive resin premix in the alumina-based ceramic slurry is 18% to 62%.

[0014] Optionally, the volume percentage of PMMA microspheres in the mixed powder is 7% to 43%, and the volume percentage of alumina ceramic powder in the mixed powder is 57% to 93%.

[0015] Optionally, the alumina ceramic powder includes a combination of alumina and one or more of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide.

[0016] Optionally, the mass percentage of aluminum oxide in the aluminum oxide ceramic powder is 65% to 95%.

[0017] Optionally, the photosensitive resin premix includes one or more combinations of hydroxyethyl acrylate, hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate.

[0018] Optionally, the mixed powder of the PMMA microspheres and the alumina ceramic powder and the photosensitive resin premix are ball-milled and mixed by a ball mill; wherein the rotation speed of the ball mill is 230 r / min to 370 r / min, and the ball milling time is 270 min to 630 min.

[0019] Optionally, the 3D printer is a photocuring 3D printer, and prints the alumina-based ceramic slurry under the irradiation of an ultraviolet light source; the layer thickness of the photocuring 3D printer is 45 μm to 155 μm, and the exposure time is 0.5 s to 21 s.

[0020] Optionally, during the degreasing process of the alumina-based ceramic core blank, the heating rate is 0.1°C / min to 5°C / min, the holding time is 25min to 185min, and the degreasing temperature is 280°C to 850°C;

[0021] During the sintering process of the alumina-based ceramic core blank, the heating rate is 1°C / min to 10°C / min, the holding time is 25min to 320min, and the sintering temperature is 950°C to 1650°C;

[0022] Wherein, during the degreasing and / or sintering process of the alumina-based ceramic core blank, the working environment in the furnace includes a vacuum environment, an inert gas environment or an air environment.

[0023] The embodiments of the present disclosure also provide an alumina-based ceramic core, which is obtained by the preparation method of the alumina-based ceramic core as described in the above embodiments.

[0024] The present disclosure provides a method for preparing an alumina-based ceramic core and an alumina-based ceramic core, which can achieve the following technical effects:

[0025] A mixed powder of PMMA microspheres and alumina ceramic powder is added to a photosensitive resin premix, and an alumina-based ceramic slurry is obtained by ball milling. Among them, since the PMMA microspheres are regular spherical and have uniform particle size, the dispersion uniformity of the powder in the alumina-based ceramic slurry can be effectively improved. On this basis, the alumina-based ceramic slurry is added to the material tank of the 3D printer and printed under the irradiation of a light source to obtain an alumina-based ceramic core blank. In this way, due to its simple printing process, low production cost, short preparation cycle, and not limited by the mold. Therefore, it can effectively reduce the process cost and improve production efficiency. In addition, the alumina-based ceramic core blank is degreased and sintered to obtain an alumina-based ceramic core. In this way, since the PMMA microspheres can be completely decomposed at a lower temperature, they are easy to remove, and their regular shape can also leave uniform pores inside the material, thereby increasing the porosity of the alumina-based ceramic core, thereby improving the core removal efficiency.

[0026] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] One or more embodiments are exemplarily described by corresponding drawings, which do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements, and the drawings do not constitute a scale limitation, and wherein:

[0028] Figure 1 is a schematic diagram of a method for preparing an alumina-based ceramic core provided by an embodiment of the present disclosure;

[0029] Figure 2 is a microscopic morphology of the fracture of an alumina-based ceramic core provided by an embodiment of the present disclosure;

[0030] Figure 3 It is a schematic diagram of the appearance of the alumina-based ceramic core provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0032] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.

[0033] Unless otherwise stated, the term "plurality" means two or more.

[0034] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B indicates: A or B.

[0035] The term "and / or" is a description of the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.

[0036] The term "correspondence" may refer to an association relationship or a binding relationship. The correspondence between A and B means that there is an association relationship or a binding relationship between A and B.

[0037] In the related art, the ceramic core can form the hollow inner cavity structure of the hollow blade of the aviation turbine engine, wherein, in the process of preparing the ceramic core, the porosity of the ceramic core can be adjusted in a variety of ways. For example, starch is used as a pore-forming agent, and a hot press molding method is used to prepare an alumina-based ceramic core. Here, after the starch is burned out, holes will be left at the burned-out position, thereby increasing the porosity of the alumina-based ceramic core. However, the molding method has a complicated process and is too dependent on the mold. For example, graphene is introduced in the process of preparing the ceramic core, and the graphene is removed by high-temperature heat treatment, thereby introducing pores, thereby increasing the porosity of the ceramic core and reducing the difficulty of removal. However, graphene has a strong absorption capacity for light, which is not conducive to the photocuring process.

[0038] Therefore, the ceramic cores prepared by the above methods all have different defects to a certain extent, thereby affecting the performance of the ceramic cores. To this end, the embodiments of the present disclosure provide a method for preparing an alumina-based ceramic core and an alumina-based ceramic core, which can effectively improve the above-mentioned partial defects, increase the porosity of the alumina-based ceramic core, and thus improve the core removal efficiency.

[0039] Combination Figure 1 As shown, the embodiment of the present disclosure provides a method for preparing an alumina-based ceramic core, comprising the following steps:

[0040] Step 101: adding a mixed powder of PMMA microspheres and alumina ceramic powder to a photosensitive resin premix, and obtaining an alumina-based ceramic slurry by ball milling;

[0041] In the embodiment of the present application, a mixed powder of PMMA microspheres and alumina ceramic powder and a photosensitive resin premix are first prepared. Here, the mixed powder of PMMA microspheres and alumina ceramic powder is prepared according to the following ratio, specifically, the volume percentage of PMMA microspheres in the mixed powder is 7% to 43%, and the volume percentage of alumina ceramic powder in the mixed powder is 57% to 93%.

[0042] In the embodiments of the present application, due to the complex structure of the alumina-based ceramic core, when the alumina-based ceramic core has an extremely high porosity, the strength of the alumina-based ceramic core will be greatly attenuated. Therefore, the higher the volume percentage of PMMA microspheres, the higher the porosity of the alumina-based ceramic core. Here, by setting the volume percentage of PMMA microspheres in the mixed powder to correspond to the volume percentage of alumina ceramic powder, both the porosity of the alumina-based ceramic core and the strength of the alumina-based ceramic core can be guaranteed.

[0043] In the embodiments of the present application, the volume percentage of PMMA microspheres and alumina ceramic powder can be adjusted according to actual needs. Optionally, the volume percentage of PMMA microspheres in the mixed powder is 7%, 10%, 15%, 20%, 25%, 30%, 35% or 40%. Correspondingly, the volume percentage of alumina ceramic powder in the mixed powder is 93%, 90%, 85%, 80%, 75%, 70%, 65% or 60%. In a specific application, the volume percentage of PMMA microspheres in the mixed powder is 10%, and the volume percentage of alumina ceramic powder in the mixed powder is 90%.

[0044] In an embodiment of the present application, the alumina ceramic powder includes alumina and one or more combinations of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide. Here, the alumina ceramic powder is mainly composed of alumina, and the remaining components are one or more combinations of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide. Optionally, the alumina ceramic powder includes alumina, silicon oxide, calcium oxide, and titanium oxide. Optionally, the alumina ceramic powder includes alumina, silicon oxide, and titanium oxide. Optionally, the alumina ceramic powder includes alumina, calcium oxide, and zirconium oxide. In a specific application, the alumina ceramic powder includes alumina, silicon oxide, and titanium oxide.

[0045] In an embodiment of the present application, the mass percentage of aluminum oxide in the aluminum oxide ceramic powder is 65% to 95%. Here, when the mass percentage of aluminum oxide in the aluminum oxide ceramic powder is 65% to 95%, the mass percentage of the remaining components (one or more combinations of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide) is 5% to 35%. Optionally, the mass percentage of aluminum oxide in the aluminum oxide ceramic powder is 65%, 70%, 75%, 80%, 85%, 90% or 95%. In a specific application, the aluminum oxide ceramic powder includes aluminum oxide, silicon oxide and titanium oxide. Among them, the mass percentage of aluminum oxide is 89.1%, the mass percentage of silicon oxide is 9.9%, and the mass percentage of titanium oxide is 1%.

[0046] In the embodiment of the present application, in order to make the alumina-based ceramic slurry easier to print, it is also necessary to adjust the types and ratios of the various substances in the photosensitive resin premix. Thereby ensuring the printing effect and material performance. Here, the photosensitive resin premix is ​​mainly composed of polymer monomers and prepolymers, wherein the photosensitive resin premix and the mixed powder will immediately cause a polymerization reaction under the irradiation of ultraviolet light of a certain wavelength, thereby completing the solid-state conversion.

[0047] Specifically, the photosensitive resin premix includes one or more combinations of hydroxyethyl acrylate, hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate. Optionally, the photosensitive resin premix includes hydroxyethyl acrylate and hydroxyethyl methacrylate. Optionally, the photosensitive resin premix includes hydroxyethyl acrylate, hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, and polyethylene glycol (200) diacrylate. Optionally, the photosensitive resin premix includes hydroxyethyl acrylate, hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate. In a specific application, the photosensitive resin premix includes hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate. The mass ratio of hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate is 9:6:10.

[0048] In the embodiment of the present application, in order to obtain the alumina-based ceramic slurry that meets the requirements, it is also necessary to adjust the volume percentage of the mixed powder in the alumina-based ceramic slurry and the volume percentage of the photosensitive resin premixed liquid. Specifically, the volume percentage of the mixed powder in the alumina-based ceramic slurry is 38% to 82%, and the volume percentage of the photosensitive resin premixed liquid in the alumina-based ceramic slurry is 18% to 62%.

[0049] Optionally, the volume percentage of the mixed powder in the alumina-based ceramic slurry is 38%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80% or 82%. Correspondingly, the volume percentage of the photosensitive resin premix in the alumina-based ceramic slurry is 62%, 60%, 55%, 50%, 45%, 40%, 35%, 30%, 25%, 20% or 18%. In a specific application, the volume percentage of the mixed powder in the alumina-based ceramic slurry is 45%, and the volume percentage of the photosensitive resin premix in the alumina-based ceramic slurry is 55%.

[0050] In the embodiment of the present application, in order to further ensure that the alumina-based ceramic slurry is fully mixed, ball milling can be performed here. Specifically, the mixed powder of the PMMA microspheres and the alumina ceramic powder and the photosensitive resin premix are ball milled and mixed by the ball mill.

[0051] Wherein, in the above-mentioned ball mill, the working parameters of the ball mill are as follows: the rotation speed of the ball mill is 230r / min to 370r / min, and the ball milling time is 270min to 630min. In this way, it is ensured that the alumina-based ceramic slurry is fully mixed. Optionally, the ball milling time can be adjusted according to the rotation speed of the ball mill. Here, it can be 230r / min, 250r / min, 300r / min, 350r / min or 370r / min. The ball milling time can be 280min, 380min, 480min, 580min or 630min. In some specific applications, the rotation speed of the ball mill is 300r / min, and the ball milling time is 480min.

[0052] Step 102: Add the alumina-based ceramic slurry into the material tank of the 3D printer, and print it under the irradiation of a light source to obtain an alumina-based ceramic core blank.

[0053] In the embodiment of the present application, the fully mixed alumina-based ceramic slurry is added into the material tank of the 3D printer. Here, the 3D printer is a light-curing 3D printer. The three-dimensional model to be printed is introduced into the light-curing 3D printer, and the alumina-based ceramic slurry is printed under the irradiation of an ultraviolet light source. Thus, an alumina-based ceramic core blank can be obtained.

[0054] In the embodiment of the present application, the layer thickness of the photocuring 3D printer will affect the accuracy of the alumina-based ceramic core blank, and the exposure time of the photocuring 3D printer will affect the preparation cycle. Here, in order to balance the accuracy and preparation cycle of the alumina-based ceramic core blank, it is necessary to reasonably adjust the layer thickness and exposure time of the photocuring 3D printer.

[0055] In an embodiment of the present application, the layer thickness of the light-curing 3D printer is 45 μm to 155 μm. Optionally, the layer thickness of the light-curing 3D printer can be 50 μm, 100 μm or 150 μm. The exposure time is 0.5 s to 21 s. Optionally, the exposure time can be 4 s, 15 or 20 s. In a specific application, the layer thickness of the light-curing 3D printer can be 50 μm and the exposure time is 4 s.

[0056] Step 103: Degreasing and sintering the alumina-based ceramic core blank to obtain an alumina-based ceramic core.

[0057] In the embodiment of the present application, after obtaining the alumina-based ceramic core blank, it is necessary to degrease and sinter it to obtain the alumina-based ceramic core. The alumina-based ceramic core blank is degreased in a tube furnace, and during the degreasing process, the corresponding working parameters need to be adjusted, including the heating rate, the holding time, the degreasing temperature and the working environment.

[0058] In the embodiment of the present application, the degreasing rate (heating rate, holding time, degreasing temperature) of the alumina-based ceramic core blank will also affect the quality of the alumina-based ceramic core to ensure that the alumina-based ceramic core does not have defects such as cracking. Here, the heating rate during the degreasing process of the alumina-based ceramic core blank is 0.1°C / min to 5°C / min, the holding time is 25min to 185min, the degreasing temperature is 280°C to 850°C, and the working environment includes a vacuum environment, an inert gas environment or an air environment.

[0059] In the embodiment of the present application, after the alumina-based ceramic core blank is degreased, the alumina-based ceramic core blank needs to be sintered to obtain an alumina-based ceramic core. The alumina-based ceramic core blank is sintered in a box furnace, and during the sintering process, corresponding working parameters need to be adjusted, including heating rate, heat preservation time, sintering temperature and working environment.

[0060] In the embodiment of the present application, the sintering rate (heating rate, holding time, sintering temperature) of the alumina-based ceramic core blank will also affect the porosity and strength of the alumina-based ceramic core. Here, the heating rate during the sintering of the alumina-based ceramic core blank is 1°C / min to 10°C / min, the holding time is 25min to 320min, the sintering temperature is 950°C to 1650°C, and the working environment includes a vacuum environment, an inert gas environment or an air environment.

[0061] In an embodiment of the present application, the inert gas includes argon.

[0062] A method for preparing an alumina-based ceramic core provided by an embodiment of the present disclosure is adopted, a mixed powder of PMMA microspheres and alumina ceramic powder is added to a photosensitive resin premix, and an alumina-based ceramic slurry is obtained by ball milling. Among them, since the PMMA microspheres are regular spherical and have uniform particle size, the dispersion uniformity of the powder in the alumina-based ceramic slurry can be effectively improved. On this basis, the alumina-based ceramic slurry is added to the material tank of the 3D printer and printed under the irradiation of a light source to obtain an alumina-based ceramic core blank. In this way, due to its simple printing process, low production cost, short preparation cycle, and not limited by the mold. Therefore, the process cost can be effectively reduced and the production efficiency can be improved. In addition, the alumina-based ceramic core blank is degreased and sintered to obtain an alumina-based ceramic core. In this way, since the PMMA microspheres can be completely decomposed at a lower temperature, they are easy to remove, and their regular shape can also leave uniform pores inside the material, thereby improving the porosity of the alumina-based ceramic core, thereby improving the core removal efficiency.

[0063] The following is combined with specific examples to verify the porosity of the alumina-based ceramic core.

[0064] Embodiment 1:

[0065] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate are mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix; a mixed powder of PMMA microspheres and alumina ceramic powder is added. The total solid content of the mixed powder is 45 vol%, wherein PMMA microspheres are 10 vol%, and alumina ceramic powder is 90 vol%; specifically, the mass ratio of alumina, silicon oxide and titanium oxide in the alumina ceramic powder is 9:1:0.1. After the mixed powder is preliminarily mixed with the photosensitive resin premix, a planetary ball mill is used for ball milling at a speed of 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0066] The alumina-based ceramic slurry is poured into the material tank of the light-curing 3D printer, and the three-dimensional model of the ceramic core is introduced. The layer thickness of the light-curing 3D printer is 50 μm, the exposure time is 4 seconds, and light-curing 3D printing is performed to obtain the alumina-based ceramic core blank.

[0067] The alumina-based ceramic core blank is placed in a tubular furnace; the tubular furnace is in an argon environment, and the temperature is increased to 600° C. at a heating rate of 0.5° C. / min and maintained for 120 minutes.

[0068] After the temperature of the tube furnace has cooled down, it is transferred to a box furnace; wherein, the box furnace is an air environment, and the temperature is first increased to 600°C at a heating rate of 1°C / min and kept warm for 60 minutes; then the temperature is increased to 1300°C at a heating rate of 4°C / min and kept warm for 120 minutes, and finally, the alumina-based ceramic core is obtained after cooling.

[0069] Embodiment 2:

[0070] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate are mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix; a mixed powder of PMMA microspheres and alumina ceramic powder is added. The total solid content of the mixed powder is 45 vol%, wherein PMMA microspheres are 20 vol%, and alumina ceramic powder is 80 vol%; specifically, the mass ratio of alumina, silicon oxide and titanium oxide in the alumina ceramic powder is 9:1:0.1. After the mixed powder is preliminarily mixed with the photosensitive resin premix, a planetary ball mill is used for ball milling at a speed of 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0071] The alumina-based ceramic slurry is poured into the material tank of the light-curing 3D printer, and the three-dimensional model of the ceramic core is introduced. The layer thickness of the light-curing 3D printer is 50 μm, the exposure time is 4 seconds, and light-curing 3D printing is performed to obtain the alumina-based ceramic core blank.

[0072] The alumina-based ceramic core blank is placed in a tubular furnace; the tubular furnace is in an argon environment, and the temperature is increased to 600° C. at a heating rate of 0.5° C. / min and maintained for 120 minutes.

[0073] After the temperature of the tube furnace has cooled down, it is transferred to a box furnace; wherein, the box furnace is an air environment, and the temperature is first increased to 600°C at a heating rate of 1°C / min and kept warm for 60 minutes; then the temperature is increased to 1300°C at a heating rate of 4°C / min and kept warm for 120 minutes, and finally, the alumina-based ceramic core is obtained after cooling.

[0074] Embodiment three:

[0075] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate are mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix; a mixed powder of PMMA microspheres and alumina ceramic powder is added. The total solid content of the mixed powder is 45 vol%, wherein PMMA microspheres are 10 vol%, and alumina ceramic powder is 90 vol%; specifically, the mass ratio of alumina, silicon oxide and titanium oxide in the alumina ceramic powder is 9:1:0.1. After the mixed powder is preliminarily mixed with the photosensitive resin premix, a planetary ball mill is used for ball milling at a speed of 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0076] The alumina-based ceramic slurry is poured into the material tank of the light-curing 3D printer, and the three-dimensional model of the ceramic core is introduced. The layer thickness of the light-curing 3D printer is 50 μm, the exposure time is 4 seconds, and light-curing 3D printing is performed to obtain the alumina-based ceramic core blank.

[0077] The alumina-based ceramic core blank is placed in a tubular furnace; the tubular furnace is in an argon environment, and the temperature is increased to 600° C. at a heating rate of 0.5° C. / min and maintained for 120 minutes.

[0078] After the temperature of the tube furnace has cooled down, it is transferred to a box furnace; wherein, the box furnace is an air environment, and the temperature is first increased to 600°C at a heating rate of 1°C / min and kept warm for 60 minutes; then the temperature is increased to 1200°C at a heating rate of 4°C / min and kept warm for 120 minutes, and finally, the alumina-based ceramic core is obtained after cooling.

[0079] Embodiment 4:

[0080] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate are mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix; a mixed powder of PMMA microspheres and alumina ceramic powder is added. The total solid content of the mixed powder is 45 vol%, wherein PMMA microspheres are 20 vol%, and alumina ceramic powder is 80 vol%; specifically, the mass ratio of alumina, silicon oxide and titanium oxide in the alumina ceramic powder is 9:1:0.1. After the mixed powder is preliminarily mixed with the photosensitive resin premix, a planetary ball mill is used for ball milling at a speed of 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0081] The alumina-based ceramic slurry is poured into the material tank of the light-curing 3D printer, and the three-dimensional model of the ceramic core is introduced. The layer thickness of the light-curing 3D printer is 50 μm, the exposure time is 4 seconds, and light-curing 3D printing is performed to obtain the alumina-based ceramic core blank.

[0082] The alumina-based ceramic core blank is placed in a tubular furnace; the tubular furnace is in an argon environment, and the temperature is increased to 600° C. at a heating rate of 0.5° C. / min and maintained for 120 minutes.

[0083] After the temperature of the tube furnace has cooled down, it is transferred to a box furnace; wherein, the box furnace is an air environment, and the temperature is first increased to 600°C at a heating rate of 1°C / min and kept warm for 60 minutes; then the temperature is increased to 1200°C at a heating rate of 4°C / min and kept warm for 120 minutes, and finally, the alumina-based ceramic core is obtained after cooling.

[0084] The alumina-based ceramic core obtained in the above-mentioned embodiment was tested, and the following Table 1 was obtained based on the porosity, bending strength and volume density obtained in the test.

[0085] Porosity Bending strength Bulk density Embodiment 1 43.87％ 71.83MPa <![CDATA[2.02g / cm 3 ]]> Embodiment 2 46.81％ 61.20MPa <![CDATA[1.93g / cm 3 ]]> Embodiment 3 48.60％ 48.98MPa <![CDATA[1.89g / cm 3 ]]> Embodiment 4 50.48％ 46.77MPa <![CDATA[1.81g / cm 3 ]]>

[0086] Table 1

[0087] It can be seen from Table 1 above that by adopting the preparation method of the alumina-based ceramic core provided by the present application, the porosity of the alumina-based ceramic core can be further improved, thereby improving the core removal efficiency.

[0088] The embodiments of the present disclosure also provide an alumina-based ceramic core, which is obtained by the preparation method of the alumina-based ceramic core as described in the above embodiments.

[0089] The alumina-based ceramic core prepared by the above method is combined with Figure 2The figure shows the fracture microstructure of the alumina-based ceramic core. Figure 3 The figure shows the appearance of the alumina-based ceramic core.

[0090] The above description and the accompanying drawings sufficiently illustrate the embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Unless explicitly required, individual components and functions are optional, and the order of operations may vary. Portions and features of some embodiments may be included in or replace portions and features of other embodiments. The embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for preparing an alumina-based ceramic core, characterized in that: The following steps are involved: The mixed powder of PMMA microspheres and alumina ceramic powder is added into the photosensitive resin premixed liquid, and the alumina-based ceramic slurry is obtained by ball milling; Adding alumina-based ceramic slurry into a material tank of a 3D printer and printing under light source to obtain an alumina-based ceramic core blank; The alumina-based ceramic core blank is degreased and sintered to obtain the alumina-based ceramic core.

2. The method for preparing an alumina-based ceramic core according to claim 1, characterized in that: The volume percentage of the mixed powder in the alumina-based ceramic slurry is 38% to 82%, and the volume percentage of the photosensitive resin premixed liquid in the alumina-based ceramic slurry is 18% to 62%.

3. The method for preparing an alumina-based ceramic core according to claim 2, characterized in that: The volume percentage of PMMA microspheres in the mixed powder is 7% to 43%, and the volume percentage of alumina ceramic powder in the mixed powder is 57% to 93%.

4. The method for preparing an alumina-based ceramic core according to claim 1, characterized in that: The alumina ceramic powder includes a combination of alumina and one or more of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide and yttrium oxide.

5. The method for preparing an alumina-based ceramic core according to claim 4, characterized in that: The mass percentage of aluminum oxide in the aluminum oxide ceramic powder is 65% to 95%.

6. The method for preparing an alumina-based ceramic core according to any one of claims 1 to 5, characterized in that: The photosensitive resin premix includes one or more combinations of hydroxyethyl acrylate, hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate.

7. The method for preparing an alumina-based ceramic core according to any one of claims 1 to 5, characterized in that: The mixed powder of the PMMA microspheres and the alumina ceramic powder and the photosensitive resin premix are ball-milled and mixed by a ball mill; wherein the rotation speed of the ball mill is 230 r / min to 370 r / min, and the ball milling time is 270 min to 630 min.

8. The method for preparing an alumina-based ceramic core according to any one of claims 1 to 5, characterized in that: The 3D printer is a photocuring 3D printer, and prints alumina-based ceramic slurry under the irradiation of an ultraviolet light source; the layer thickness of the photocuring 3D printer is 45 μm to 155 μm, and the exposure time is 0.5 s to 21 s.

9. The method for preparing an alumina-based ceramic core according to any one of claims 1 to 5, characterized in that: During the degreasing process of the alumina-based ceramic core blank, the heating rate is 0.1°C / min to 5°C / min, the heat preservation time is 25min to 185min, and the degreasing temperature is 280°C to 850°C; During the sintering process of the alumina-based ceramic core blank, the heating rate is 1°C / min to 10°C / min, the holding time is 25min to 320min, and the sintering temperature is 950°C to 1650°C; Wherein, during the degreasing and / or sintering process of the alumina-based ceramic core blank, the working environment in the furnace includes a vacuum environment, an inert gas environment or an air environment.

10. An alumina-based ceramic core, characterized in that: Obtained by the method for preparing an alumina-based ceramic core according to any one of claims 1 to 9.

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