A method for producing an alumina-based ceramic core and an alumina-based ceramic core

Abstract

This application relates to the field of ceramic additive manufacturing technology, and discloses a method for preparing an alumina-based ceramic core and the alumina-based ceramic core itself. The preparation method includes the following steps: adding a mixture of PMMA microspheres and alumina ceramic powder to a photosensitive resin premix, and ball milling to obtain an alumina-based ceramic slurry; adding the alumina-based ceramic slurry into the feed tank of a 3D printer, and printing under light source irradiation to obtain an alumina-based ceramic core blank; and debinding and sintering the alumina-based ceramic core blank to obtain the alumina-based ceramic core. This preparation method effectively reduces process costs, improves production efficiency, and also increases the porosity of the alumina-based ceramic core, thereby improving core removal efficiency.

Description

Technical Field

[0001] This application relates to the field of ceramic additive manufacturing technology, and to a method for preparing an alumina-based ceramic core and the alumina-based ceramic core itself. Background Technology

[0002] Ceramic cores can form cavities for castings with complex or difficult-to-form shapes, and are currently commonly used to form the hollow internal cavity structure of hollow blades for aero-engines. This results in hollow turbine blades with higher cooling efficiency and the ability to withstand higher operating temperatures, thereby effectively improving the thrust-to-weight ratio of aero-engines. Currently, alumina ceramics are typically used to make alumina-based ceramic cores, as alumina ceramics possess high strength, high temperature resistance, corrosion resistance, and good insulation properties.

[0003] When using alumina-based ceramic cores in the hollow cavity structure of hollow blades, a high porosity is required to improve core removal efficiency. For example, related technologies use starch as a pore-forming agent to adjust porosity, or adjust porosity by varying the proportions and particle sizes of powders.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art:

[0005] The above methods can improve porosity to some extent, but the molding process is costly and time-consuming. Furthermore, the resulting porosity may affect the core removal efficiency.

[0006] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0007] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0008] This disclosure provides a method for preparing an alumina-based ceramic core and an alumina-based ceramic core, which can effectively reduce process costs, improve production efficiency, and increase 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 includes the following steps:

[0010] A mixture of PMMA microspheres and alumina ceramic powder was added to a photosensitive resin premix, and then ball-milled to obtain an alumina-based ceramic slurry.

[0011] Alumina-based ceramic slurry is added into the feed tank of a 3D printer and printed under light source to obtain an alumina-based ceramic core blank.

[0012] Alumina-based ceramic core blanks are degreased and sintered to obtain alumina-based ceramic cores.

[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 one or more combinations of alumina and silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide.

[0016] Optionally, the alumina ceramic powder contains 65% to 95% alumina by mass.

[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 PMMA microspheres and alumina ceramic powder and the photosensitive resin premix are ball-milled and mixed using 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 photopolymerization 3D printer, and the alumina-based ceramic slurry is printed under ultraviolet light irradiation; the layer thickness of the photopolymerization 3D printer is 45μm to 155μm, and the exposure time is 0.5s to 21s.

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

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

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

[0023] This disclosure also provides an alumina-based ceramic core, obtained by the alumina-based ceramic core preparation method described in the foregoing embodiments.

[0024] The method for preparing an alumina-based ceramic core and the alumina-based ceramic core provided in this disclosure can achieve the following technical effects:

[0025] A mixture of PMMA microspheres and alumina ceramic powder is added to a photosensitive resin premix and ball-milled to obtain an alumina-based ceramic slurry. The PMMA microspheres, being regularly spherical and uniform in size, effectively improve the dispersion uniformity of the powder in the alumina-based ceramic slurry. The alumina-based ceramic slurry is then added to the feed chamber of a 3D printer and printed under illumination to obtain an alumina-based ceramic core preform. This method is simple, has low production costs, a short preparation cycle, and is not limited by molds. Therefore, it effectively reduces process costs and improves production efficiency. Furthermore, the alumina-based ceramic core preform is degreased and sintered to obtain the alumina-based ceramic core. Since the PMMA microspheres can decompose completely at relatively low temperatures, they are easily removed, and their regular shape leaves uniform pores within the material, thereby increasing the porosity of the alumina-based ceramic core and improving core removal efficiency.

[0026] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein:

[0028] Figure 1 This is a schematic diagram of a method for preparing an alumina-based ceramic core according to an embodiment of this disclosure;

[0029] Figure 2 This is a microscopic morphology image of the fracture surface of an alumina-based ceramic core provided in an embodiment of this disclosure;

[0030] Figure 3 This is a schematic diagram of the appearance of the alumina-based ceramic core provided in the embodiments of this disclosure. Detailed Implementation

[0031] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0032] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

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

[0034] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0035] The term "and / or" describes an association 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" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0037] In related technologies, ceramic cores can form the hollow internal cavity structure of hollow blades in aero-turbine engines. During the preparation of ceramic cores, their porosity can be adjusted in various ways. For example, starch can be used as a pore-forming agent, and alumina-based ceramic cores can be prepared using hot-press molding. Here, after the starch burns away, it leaves pores at the burn-off sites, thereby increasing the porosity of the alumina-based ceramic core. However, this molding method is complex and overly reliant on molds. Another approach is to introduce graphene during the preparation of the ceramic core, removing it through high-temperature heat treatment, thus introducing pores and increasing the porosity of the ceramic core while reducing the difficulty of removal. However, graphene has a strong light absorption capacity, which is detrimental to the photocuring process.

[0038] Therefore, the ceramic cores obtained by the above methods all have different defects to some extent, which affects the performance of the ceramic cores. To address this, this disclosure provides a method for preparing an alumina-based ceramic core and an alumina-based ceramic core, which can effectively improve some of the above-mentioned defects, increase the porosity of the alumina-based ceramic core, and thus improve the core removal efficiency.

[0039] Combination Figure 1 As shown in the embodiments of this disclosure, a method for preparing an alumina-based ceramic core is provided, comprising the following steps:

[0040] Step 101: Add the mixed powder of PMMA microspheres and alumina ceramic powder to the photosensitive resin premix, and obtain alumina-based ceramic slurry by ball milling;

[0041] In the embodiments of this application, a mixed powder of PMMA microspheres and alumina ceramic powder, as well as a photosensitive resin premix, are first prepared. Here, the mixed powder of PMMA microspheres and alumina ceramic powder is prepared according to the following proportions: 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 this application, due to the complex structure of the alumina-based ceramic core, its strength is significantly reduced when the alumina-based ceramic core has extremely high porosity. 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 with the volume percentage of alumina ceramic powder, both the porosity and strength of the alumina-based ceramic core can be guaranteed.

[0043] In the embodiments of this application, the volume percentage content of PMMA microspheres and alumina ceramic powder can be adjusted according to actual needs. Optionally, the volume percentage content of PMMA microspheres in the mixed powder is 7%, 10%, 15%, 20%, 25%, 30%, 35%, or 40%. Correspondingly, the volume percentage content 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 content of PMMA microspheres in the mixed powder is 10%, and the volume percentage content of alumina ceramic powder in the mixed powder is 90%.

[0044] In embodiments of this application, the alumina ceramic powder comprises 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 primarily composed of alumina, with the remaining components being one or more combinations of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide. Optionally, the alumina ceramic powder comprises alumina, silicon oxide, calcium oxide, and titanium oxide. Optionally, the alumina ceramic powder comprises alumina, silicon oxide, and titanium oxide. Optionally, the alumina ceramic powder comprises alumina, calcium oxide, and zirconium oxide. In a specific application, the alumina ceramic powder comprises alumina, silicon oxide, and titanium oxide.

[0045] In embodiments of this application, the alumina ceramic powder contains 65% to 95% alumina by mass. Here, when the alumina ceramic powder contains 65% to 95% alumina by mass, the remaining components (one or more combinations of silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, and yttrium oxide) contain 5% to 35% by mass. Optionally, the alumina ceramic powder contains 65%, 70%, 75%, 80%, 85%, 90%, or 95% alumina by mass. In a specific application, the alumina ceramic powder includes alumina, silicon oxide, and titanium oxide. The alumina by mass is 89.1%, the silicon oxide by mass is 9.9%, and the titanium oxide by mass is 1%.

[0046] In the embodiments of this application, to make the alumina-based ceramic slurry easier to print, it is also necessary to adjust the type and ratio of each substance in the photosensitive resin premix. This ensures the printing effect and material properties. Here, the photosensitive resin premix mainly consists of polymer monomers and prepolymers. The photosensitive resin premix and the mixed powder will immediately undergo a polymerization reaction under ultraviolet light of a certain wavelength, thereby completing the solidification conversion.

[0047] Specifically, the photosensitive resin premix comprises 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 comprises hydroxyethyl acrylate and hydroxyethyl methacrylate. Optionally, the photosensitive resin premix comprises hydroxyethyl acrylate, hydroxyethyl methacrylate, 1,6-hexanediol diacrylate, and polyethylene glycol (200) diacrylate. Optionally, the photosensitive resin premix comprises hydroxyethyl acrylate, hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate. In a specific application, the photosensitive resin premix comprises 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 embodiments of this application, in order to obtain the required alumina-based ceramic slurry, it is also necessary to adjust the volume percentage of the mixed powder and the volume percentage of the photosensitive resin premix in the alumina-based ceramic slurry. 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 premix 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 embodiments of this application, to further ensure a thoroughly mixed alumina-based ceramic slurry, ball milling can be performed. Specifically, the mixed powder of PMMA microspheres and alumina ceramic powder and the photosensitive resin premix are ball-milled and mixed.

[0051] In the aforementioned ball mill, the operating parameters are as follows: the ball mill speed is 230 r / min to 370 r / min, and the milling time is 270 min to 630 min. This ensures a thoroughly mixed alumina-based ceramic slurry. Optionally, the milling time can be adjusted according to the ball mill speed. Here, it can be 230 r / min, 250 r / min, 300 r / min, 350 r / min, or 370 r / min. The milling time can be 280 min, 380 min, 480 min, 580 min, or 630 min. In some specific applications, the ball mill speed is 300 r / min, and the milling time is 480 min.

[0052] Step 102: Add the alumina-based ceramic slurry into the 3D printer's feed tank and print it under light source to obtain an alumina-based ceramic core blank.

[0053] In the embodiments of this application, a thoroughly mixed alumina-based ceramic slurry is added to the feed tank of a 3D printer. Here, the 3D printer is a photopolymer 3D printer. The desired three-dimensional model is imported into the photopolymer 3D printer, and the alumina-based ceramic slurry is printed under ultraviolet light irradiation. This results in an alumina-based ceramic core blank.

[0054] In the embodiments of this application, the layer thickness of the photopolymer 3D printer affects the accuracy of the alumina-based ceramic core preform, and the exposure time of the photopolymer 3D printer affects the preparation cycle. Here, in order to balance the accuracy of the alumina-based ceramic core preform and the preparation cycle, it is necessary to reasonably adjust the layer thickness and exposure time of the photopolymer 3D printer.

[0055] In the embodiments of this application, the layer thickness of the photopolymer 3D printer is from 45 μm to 155 μm. Optionally, the layer thickness of the photopolymer 3D printer can be 50 μm, 100 μm, or 150 μm. The exposure time is from 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 photopolymer 3D printer can be 50 μm, and the exposure time is 4 s.

[0056] Step 103: Degrease and sinter the alumina-based ceramic core blank to obtain the alumina-based ceramic core.

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

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

[0059] In the embodiments of this application, after the alumina-based ceramic core blank is degreased, it needs to be sintered to obtain the alumina-based ceramic core. The alumina-based ceramic core blank is sintered in a box furnace, and during the sintering process, corresponding operating parameters need to be adjusted, specifically including the heating rate, holding time, sintering temperature, and working environment.

[0060] In the embodiments of this application, the sintering rate (heating rate, holding time, and sintering temperature) of the alumina-based ceramic core blank also affects the porosity and strength of the alumina-based ceramic core. Here, the heating rate during the sintering process 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 the embodiments of this application, the inert gas includes argon.

[0062] The method for preparing an alumina-based ceramic core according to the embodiments of this disclosure involves adding a mixture of PMMA microspheres and alumina ceramic powder to a photosensitive resin premix, and then ball milling to obtain an alumina-based ceramic slurry. The PMMA microspheres, being regularly spherical and uniform in size, effectively improve the dispersion uniformity of the powder in the alumina-based ceramic slurry. The alumina-based ceramic slurry is then added to the feed tank of a 3D printer and printed under light source irradiation to obtain an alumina-based ceramic core preform. This method is simple to implement, has low production costs, a short preparation cycle, and is not limited by molds. Therefore, it effectively reduces process costs and improves production efficiency. Furthermore, the alumina-based ceramic core preform is degreased and sintered to obtain the alumina-based ceramic core. Since the PMMA microspheres can decompose completely at relatively low temperatures, they are easily removed, and their regular shape leaves uniform pores within the material, thereby increasing the porosity of the alumina-based ceramic core and improving the core removal efficiency.

[0063] The porosity of the alumina-based ceramic core is verified below with reference to specific embodiments.

[0064] Example 1:

[0065] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate were mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix. A mixture of PMMA microspheres and alumina ceramic powder was then added. The total solid content of the mixed powder was 45 vol%, with PMMA microspheres comprising 10 vol% and alumina ceramic powder comprising 90 vol%. Specifically, the mass ratio of alumina, silica, and titanium dioxide in the alumina ceramic powder was 9:1:0.1. After initial mixing of the mixed powder with the photosensitive resin premix, the mixture was ball-milled in a planetary ball mill at 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0066] Alumina-based ceramic slurry is poured into the feed tank of a photopolymer 3D printer, and a three-dimensional model of a ceramic core is imported. The photopolymer 3D printer has a layer thickness of 50μm and an exposure time of 4s to perform photopolymer 3D printing to obtain an alumina-based ceramic core blank.

[0067] The alumina-based ceramic core blank is placed in a tube furnace; the tube furnace is in an argon atmosphere, and the temperature is increased to 600℃ at a heating rate of 0.5℃ / min and held for 120min.

[0068] After the temperature of the tube furnace has cooled down, it is transferred to the box furnace. The box furnace is an air environment. First, the temperature is raised to 600℃ at a heating rate of 1℃ / min and held for 60min. Then, the temperature is raised to 1300℃ at a heating rate of 4℃ / min and held for 120min. Finally, after cooling, an alumina-based ceramic core is obtained.

[0069] Example 2:

[0070] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate were mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix. A mixture of PMMA microspheres and alumina ceramic powder was then added. The total solid content of the mixed powder was 45 vol%, with PMMA microspheres comprising 20 vol% and alumina ceramic powder comprising 80 vol%. Specifically, the mass ratio of alumina, silica, and titanium dioxide in the alumina ceramic powder was 9:1:0.1. After initial mixing of the mixed powder with the photosensitive resin premix, the mixture was ball-milled in a planetary ball mill at 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0071] Alumina-based ceramic slurry is poured into the feed tank of a photopolymer 3D printer, and a three-dimensional model of a ceramic core is imported. The photopolymer 3D printer has a layer thickness of 50μm and an exposure time of 4s to perform photopolymer 3D printing to obtain an alumina-based ceramic core blank.

[0072] The alumina-based ceramic core blank is placed in a tube furnace; the tube furnace is in an argon atmosphere, and the temperature is increased to 600℃ at a heating rate of 0.5℃ / min and held for 120min.

[0073] After the temperature of the tube furnace has cooled down, it is transferred to the box furnace. The box furnace is an air environment. First, the temperature is raised to 600℃ at a heating rate of 1℃ / min and held for 60min. Then, the temperature is raised to 1300℃ at a heating rate of 4℃ / min and held for 120min. Finally, after cooling, an alumina-based ceramic core is obtained.

[0074] Example 3:

[0075] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate were mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix. A mixture of PMMA microspheres and alumina ceramic powder was then added. The total solid content of the mixed powder was 45 vol%, with PMMA microspheres comprising 10 vol% and alumina ceramic powder comprising 90 vol%. Specifically, the mass ratio of alumina, silica, and titanium dioxide in the alumina ceramic powder was 9:1:0.1. After initial mixing of the mixed powder with the photosensitive resin premix, the mixture was ball-milled in a planetary ball mill at 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0076] Alumina-based ceramic slurry is poured into the feed tank of a photopolymer 3D printer, and a three-dimensional model of a ceramic core is imported. The photopolymer 3D printer has a layer thickness of 50μm and an exposure time of 4s to perform photopolymer 3D printing to obtain an alumina-based ceramic core blank.

[0077] The alumina-based ceramic core blank is placed in a tube furnace; the tube furnace is in an argon atmosphere, and the temperature is increased to 600℃ at a heating rate of 0.5℃ / min and held for 120min.

[0078] After the temperature of the tube furnace has cooled down, it is transferred to the box furnace. The box furnace is an air environment. First, the temperature is raised to 600℃ at a heating rate of 1℃ / min and held for 60min. Then, the temperature is raised to 1200℃ at a heating rate of 4℃ / min and held for 120min. Finally, after cooling, an alumina-based ceramic core is obtained.

[0079] Example 4:

[0080] Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate, and trimethylolpropane triacrylate were mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix. A mixture of PMMA microspheres and alumina ceramic powder was then added. The total solid content of the mixed powder was 45 vol%, with PMMA microspheres comprising 20 vol% and alumina ceramic powder comprising 80 vol%. Specifically, the mass ratio of alumina, silica, and titanium dioxide in the alumina ceramic powder was 9:1:0.1. After initial mixing of the mixed powder with the photosensitive resin premix, the mixture was ball-milled in a planetary ball mill at 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry.

[0081] Alumina-based ceramic slurry is poured into the feed tank of a photopolymer 3D printer, and a three-dimensional model of a ceramic core is imported. The photopolymer 3D printer has a layer thickness of 50μm and an exposure time of 4s to perform photopolymer 3D printing to obtain an alumina-based ceramic core blank.

[0082] The alumina-based ceramic core blank is placed in a tube furnace; the tube furnace is in an argon atmosphere, and the temperature is increased to 600℃ at a heating rate of 0.5℃ / min and held for 120min.

[0083] After the temperature of the tube furnace has cooled down, it is transferred to the box furnace. The box furnace is an air environment. First, the temperature is raised to 600℃ at a heating rate of 1℃ / min and held for 60min. Then, the temperature is raised to 1200℃ at a heating rate of 4℃ / min and held for 120min. Finally, after cooling, an alumina-based ceramic core is obtained.

[0084] The alumina-based ceramic cores obtained from the above embodiments were tested, and the porosity, flexural strength, and bulk density were obtained from the tests, resulting in Table 1 below.

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

[0086] Table 1

[0087] As shown in Table 1 above, by adopting the alumina-based ceramic core preparation method provided in this application, the porosity of the alumina-based ceramic core can be further improved, thereby improving the core removal efficiency.

[0088] This disclosure also provides an alumina-based ceramic core, obtained by the alumina-based ceramic core preparation method described in the foregoing embodiments.

[0089] The alumina-based ceramic core prepared by the above method, combined with Figure 2The image shown is a microscopic morphology diagram of the fracture surface of an alumina-based ceramic core. Combined with... Figure 3 The image shown is a schematic diagram of the appearance of an alumina-based ceramic core.

[0090] The foregoing description and accompanying drawings fully illustrate 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. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. 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 its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A method for producing an alumina-based ceramic core, characterized by, Includes the following steps: Hydroxyethyl methacrylate, polyethylene glycol (200) diacrylate and trimethylolpropane triacrylate were mixed in a mass ratio of 9:6:10 to prepare a photosensitive resin premix. A mixture of PMMA microspheres and alumina ceramic powder is added; wherein the total solid content of the mixture is 45 vol%, the PMMA microspheres are 10 vol% or 20 vol%, and the alumina ceramic powder is 90 vol% or 80 vol%; the mass ratio of alumina, silicon oxide and titanium oxide in the alumina ceramic powder is 9:1:0.

1. After the mixed powder and photosensitive resin premix were initially mixed, the mixture was ball-milled in a planetary ball mill at a speed of 300 r / min for 480 min to obtain a fully mixed alumina-based ceramic slurry. Alumina-based ceramic slurry is poured into the feed tank of a photopolymer 3D printer, and a three-dimensional model of a ceramic core is imported. The photopolymer 3D printer has a layer thickness of 50μm and an exposure time of 4s to perform photopolymer 3D printing to obtain an alumina-based ceramic core blank. The alumina-based ceramic core blank is placed in a tube furnace; the tube furnace is in an argon atmosphere, and the temperature is raised to 600℃ at a heating rate of 0.5℃ / min and held for 120min. After the temperature of the tube furnace has cooled down, it is transferred to the box furnace. The box furnace is an air environment. First, the temperature is raised to 600℃ at a heating rate of 1℃ / min and held for 60min. Then, the temperature is raised to 1200℃ or 1300℃ at a heating rate of 4℃ / min and held for 120min. Finally, after cooling, an alumina-based ceramic core is obtained.

2. An alumina-based ceramic core, characterized by, The alumina-based ceramic core was obtained by the preparation method described in claim 1.

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