Flaky alumina reinforced ceramic core and preparation method thereof

Abstract

The invention relates to the technical field of ceramic material preparation, in particular to a flaky alumina reinforced ceramic core and a preparation method thereof. The flaky alumina reinforced ceramic core is prepared from the following raw materials: solid-phase mixed powder and photosensitive resin mixed liquid, wherein the volume V1 of the solid-phase mixed powder and the volume V2 of the photosensitive resin mixed liquid meet the condition that V1: V2 = (45-60): (40-55); the solid-phase mixed powder comprises an aluminum oxide precursor and a crystal form regulating agent, the mass of the aluminum oxide precursor is 2-8% of the total mass of the solid-phase mixed powder, and the mass of the crystal form regulating agent is 2-4% of the total mass of the solid-phase mixed powder. According to the flaky aluminum oxide reinforced ceramic core, through the design of high solid content, the introduction, regulation and control of flaky aluminum oxide and the effect of the crystal form regulating agent, the number of weak areas, generated in the photocuring additive manufacturing process, of a layered interface of the ceramic core is synergistically reduced.

Description

Technical Field

[0001] The present application relates to the technical field of ceramic material preparation, and in particular to a flaky alumina reinforced ceramic core and a preparation method thereof. Background Art

[0002] Ceramic materials have excellent mechanical properties, wear resistance, corrosion resistance, and thermal shock resistance, making them suitable for a wide range of applications. However, currently, in fields such as fine chemicals, high-end equipment, advanced manufacturing, aerospace, and biomedicine, there are higher demands for advanced ceramic components with complex and precise structures. Therefore, developing technologies for fabricating these complex and high-precision ceramic components is of great significance. Ceramic photopolymerization 3D printing offers advantages such as mold-free operation, high precision, and superior surface quality, making it ideal for manufacturing ceramic cores with complex shapes. Photopolymerization 3D printing generally involves mixing photosensitive resin with ceramic powder to create a mixture. The mixture is then cured layer by layer using ultraviolet light to form a three-dimensional solid. This process results in the typical layered structure of the produced ceramic parts. The formation of the interlaminar interfaces within this layered structure primarily relies on transition layers formed during the settling of the ceramic powder slurry. These interlaminar interfaces, after degreasing, form the layered structure. Consequently, the layers of the layered structure are connected primarily through discrete ceramic particles, making these interlaminar interfaces the weakest regions of the entire ceramic material.

[0003] At present, the sedimentation of ceramic slurries is mainly suppressed by using ceramic slurries with higher solid content and greater stability. For example: (1) Directly using alumina-based ceramic slurries with low viscosity, high solid content, good fluidity, and high dispersion stability to prepare ceramic cores through photocuring 3D printing technology; (2) Improving the distribution of alumina ceramic particles by designing and optimizing the surfactant or dispersant content in the ceramic slurry, the thickness of a single layer of printing, and adjusting the ceramic particle size and the volume fraction of the ceramic particle content, while optimizing the printing speed of photocuring 3D printing technology.

[0004] Although the above method can improve the connection strength between the layered structures of the ceramic core to a certain extent, the entire ceramic core still has weak areas at the layered interfaces. Summary of the Invention

[0005] The present application provides a flaky alumina reinforced ceramic core and a preparation method thereof to solve the following technical problem: how to reduce the number of weak areas of the ceramic core.

[0006] In a first aspect, an embodiment of the present application provides a flaky alumina reinforced ceramic core, the raw materials of which include: a solid-phase mixed powder and a photosensitive resin mixed liquid, the volume V1 of the solid-phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=(45 to 60):(40 to 55); the solid-phase mixed powder includes an alumina precursor and a crystal form regulator, the mass of the alumina precursor is 2% to 8% of the total mass of the solid-phase mixed powder, and the mass of the crystal form regulator is 2% to 4% of the total mass of the solid-phase mixed powder.

[0007] Optionally, the type of the aluminum oxide precursor includes at least one of the following: aluminum hydroxide, γ-Al2O3, ρ-Al2O3, δ-Al2O3 and boehmite; and / or

[0008] The crystal shape modifier includes at least one of the following: aluminum fluoride, calcium fluoride and magnesium fluoride.

[0009] Optionally, the solid-phase mixed powder further includes a matrix ceramic powder and a sintering aid, the mass of the matrix ceramic powder is 85% to 95% of the total mass of the solid-phase mixed powder, and the mass of the sintering aid is 1% to 3% of the total mass of the solid-phase mixed powder.

[0010] Optionally, the type of the matrix ceramic powder includes at least one of the following: silicon dioxide, aluminum oxide, calcium oxide and zircon; and / or

[0011] The sintering aid includes at least one of the following types: MgO, TiO2 and MnO2.

[0012] Optionally, the median particle size of the matrix ceramic powder is 0.5 μm to 20 μm; and / or

[0013] The median particle size of the aluminum oxide precursor is 0.5 μm to 5 μm; and / or

[0014] The median particle size of the crystal shape modifier is 0.2 μm to 1 μm; and / or

[0015] The median particle size of the sintering aid is 0.1 μm to 0.5 μm.

[0016] Optionally, the photosensitive resin mixture includes an oligomer, a monomer diluent and a photoinitiator, the mass of the oligomer is 32% to 64% of the total mass of the photosensitive resin mixture, the mass of the monomer diluent is 35% to 65% of the total mass of the photosensitive resin mixture, and the mass of the photoinitiator is 1% to 3% of the total mass of the photosensitive resin mixture.

[0017] Optionally, the type of the oligomer includes at least one of the following: epoxy acrylate, polyurethane acrylate and silicone polyurethane acrylate; and / or

[0018] The monomer diluent comprises at least one of the following: 1,6-hexanediol diacrylate, isobornyl acrylate, dipropylene glycol diacrylate and trimethylolpropane triacrylate; and / or

[0019] The photoinitiator comprises at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester and 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide.

[0020] In a second aspect, an embodiment of the present application provides a method for preparing the flaky alumina reinforced ceramic core described in the first aspect, the method comprising:

[0021] Mixing the solid phase mixed powder, the photosensitive resin mixed liquid and the dispersant to obtain a ceramic paste;

[0022] The ceramic paste is subjected to segmented light-curing 3D printing to obtain a ceramic core blank;

[0023] The ceramic core blank is sintered to obtain an alumina reinforced ceramic core.

[0024] Optionally, the degreasing process includes a first degreasing stage, a second degreasing stage and a third degreasing stage, the temperature of the first degreasing stage is 200° C. to 350° C., the heating rate of the first degreasing stage is 0.2° C. / min to 2° C. / min, and the duration of the first degreasing stage is 60 min to 240 min; and / or

[0025] The temperature of the second degreasing section is 380° C. to 450° C., the heating rate of the second degreasing section is 0.2° C. / min to 2° C. / min, and the duration of the second degreasing section is 60 min to 180 min; and / or

[0026] The temperature of the third degreasing section is 550° C. to 650° C., the heating rate of the third degreasing section is 0.2° C. / min to 5° C. / min, and the duration of the third degreasing section is 120 min to 240 min.

[0027] Optionally, the temperature of the sintering treatment is 1400° C. to 1600° C., the heating rate of the sintering treatment is 2° C. / min to 5° C. / min, and the duration of the sintering treatment is 120 min to 300 min.

[0028] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0029] An embodiment of the present application provides a flaky alumina reinforced ceramic core, the raw materials of which first control the volume ratio of the solid-phase mixed powder and the photosensitive resin mixed liquid (45 to 60): (40 to 55), which greatly increases the content of the solid-phase mixed powder in the raw materials, reduces the interlayer shrinkage difference stress of the solid-phase mixed powder, thereby increasing the contact probability between the particles of the solid-phase mixed powder, and making the interlayer interfaces of the solid-phase mixed powder more tightly bonded. In addition, an alumina precursor and a crystal shape regulator are introduced into the solid-phase mixed powder. During the solid-phase mixed powder forming stage, the alumina precursor can form a uniformly dispersed flaky alumina reinforcing phase under the action of the crystal shape regulator. These flaky alumina reinforcing phases will be randomly and evenly distributed during the forming stage of the flaky alumina reinforced ceramic core. When the flaky alumina reinforcing phases span adjacent interfaces, these flaky alumina reinforcing phases physically bridge the layered interfaces, thereby improving the bonding strength of the two layered interfaces. At the same time, when cracks propagate at the interlayer interface, the bridged flaky alumina reinforcing phases will cause the cracks to deflect, bypass or pull out, thereby hindering the expansion of cracks in the weak areas of the two interfaces, thereby strengthening the weak areas of the interlayer interface. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A SEM image of a flaky alumina reinforced ceramic core is provided for Example 2 of the present application;

[0033] Figure 2 A schematic flow chart of a method for preparing a flaky alumina reinforced ceramic core provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the actual process of a method for preparing a flaky alumina reinforced ceramic core provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0036] The range descriptions described in this application, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "including" used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or simultaneously; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the text, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0037] Figure 1 The SEM image of a flaky alumina reinforced ceramic core provided by Example 2 of the present application is exemplarily shown;

[0038] like Figure 1 As shown, an embodiment of the present application provides a flaky alumina reinforced ceramic core, the raw materials of the flaky alumina reinforced ceramic core include: a solid-phase mixed powder and a photosensitive resin mixed liquid, the volume V1 of the solid-phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=(45 to 60):(40 to 55); the solid-phase mixed powder includes an alumina precursor and a crystal shape regulator, the mass of the alumina precursor is 2% to 8% of the total mass of the solid-phase mixed powder, and the mass of the crystal shape regulator is 2% to 4% of the total mass of the solid-phase mixed powder.

[0039] It should be noted that the photosensitive resin mixture is a mixture of multiple resins with photosensitivity.

[0040] It should be noted that the alumina precursor refers to a raw material for forming alumina, such as aluminum hydroxide, boehmite, and the like.

[0041] It should be noted that the crystal shape regulator refers to metal fluorides, which achieve precise control of crystal morphology, crystal form and performance by changing crystal nucleation, growth dynamics and surface energy distribution.

[0042] The volume V1 of the solid phase mixed powder can be 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 or 60.

[0043] The volume V2 of the photosensitive resin mixture can be 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54 or 55.

[0044] It should be noted that the flaky alumina-reinforced ceramic core provided in the embodiments of this application, through its high solid content design, the introduction and regulation of flaky alumina, and the action of a crystal shape modifier, synergistically reduces the number of weak areas at the laminar interface generated during the photocuring additive manufacturing process. The specific mechanism is as follows:

[0045] 1. Solid content design: (1) Reduce resin content and shrinkage: A higher volume fraction of solid phase powder (45% to 60%) means a relatively lower content of photosensitive resin melt (40% to 55%). During the debinding (debinding) and sintering process after light curing, the photosensitive resin melt needs to be completely burned off. The lower the content of photosensitive resin melt, the fewer pores left after sintering and removal, and the smaller and more uniform the shrinkage.

[0046] (2) Reduce interlayer shrinkage differential stress: Both the sintering and removal of the photosensitive resin melt and the sintering of the ceramic core will cause shrinkage of the ceramic core. If the content of the photosensitive resin melt is too high, the shrinkage within and between the layers of the ceramic core may vary significantly due to factors such as the solidification gradient and slight differences in the powder bulk density, resulting in large internal stress at the interlayer interface, forming weak areas and even cracks. Ceramic cores with high solid content reduce this shrinkage differential dominated by the photosensitive resin melt and reduce interlayer stress.

[0047] (3) Enhanced inter-particle contact: High solid content allows the solid-phase mixed powder particles to be packed more densely in the green body, resulting in more inter-particle contact points. This not only improves the green body strength but also facilitates the formation of stronger neck connections in the early stages of sintering, spanning the interlayer interface and making the interface bond denser and stronger.

[0048] 2. The role of the flake-shaped alumina precursor (accounting for 2% to 8% of the solid phase): (1) Formation of a flake-shaped strengthening phase: Alumina precursors (e.g., boehmite, aluminum hydroxide) are converted to α-Al2O3 during the sintering process. Under specific conditions (assisted by a crystal shape modifier), this conversion forms flake-shaped alumina crystals with a high aspect ratio.

[0049] (2) Bridging the lamellar interface: These flake-like alumina crystals are randomly oriented during the sintering process. When these flake-like alumina crystals span adjacent printed layers (i.e., grow or distribute between two layers), their flake-like morphology can physically bridge the lamellar interface.

[0050] 1) Crack deflection and toughening: When a crack propagates along a lamellar interface, it is forced to deflect, bypass, or pull out the lamellar crystals that cross the interface. This process consumes a large amount of energy and significantly hinders the propagation of the crack at the interface, thereby strengthening the originally weak interface area.

[0051] 2) Enhanced interface bonding: The flaky alumina crystals themselves are embedded in the matrix as a strengthening phase. Their good bonding with the matrix (usually another ceramic phase) itself improves the strength and toughness of the interface area. The flaky crystals that span the interface directly "sew" the upper and lower layers together.

[0052] (3) Optimized content range (2% to 8%): If the content is too low (<2%), too few flake crystals will be formed, and the bridging effect will be insignificant. If the content is too high (>8%), it may lead to poor powder flowability (affecting printing slurry), difficult sintering, or excessive accumulation of flake crystals, which will form defects at the interface. 2% to 8% is a range that can effectively provide bridging while avoiding side effects.

[0053] 3. The role of crystal form modifiers (accounting for 2% to 4% of the solid phase):

[0054] (1) Inducing lamellar morphology: The core function of the crystal shape regulator is to promote and control the transformation of the alumina precursor into α-Al2O3 crystals with a specific lamellar morphology during the sintering process. By affecting the nucleation, growth kinetics and surface energy of the alumina crystals, the crystals are encouraged to grow preferentially along specific crystal planes, forming the desired high aspect ratio lamellar structure.

[0055] (2) Controlling the size and distribution of platelet crystals: A suitable crystal form modifier and its content (2% to 4%) help produce platelet alumina with appropriate size and aspect ratio, and relatively uniform dispersion in the matrix. Too small or too large a size, or uneven distribution, may reduce its bridging effect or introduce new stress concentration points. The modifier ensures the effective formation and optimized distribution of platelet crystals.

[0056] (3) Inhibiting abnormal grain growth: In the later stage of sintering, the crystal shape regulator may also play a role in inhibiting the excessive growth of the matrix or flake alumina grains themselves, helping to maintain the fine-grained structure and the integrity of the flake crystals and avoid the increased brittleness caused by large grains.

[0057] In summary, the embodiments of the present application provide a flaky alumina reinforced ceramic core, which synergistically reduces the number of laminar interface weak areas mainly through the following mechanisms:

[0058] (1) Physical bridging strengthening: The crystal shape modifier induces the formation of flaky aluminum oxide crystals across the interface of the aluminum oxide precursor, which is the most direct and core strengthening mechanism. These flaky aluminum oxide crystals physically connect the upper and lower printed layers like "rivets" or "sutures", greatly hindering the propagation path of cracks along the interface.

[0059] (2) Reduce interfacial stress: The design of high solid content solid phase mixed powder significantly reduces the shrinkage and shrinkage difference caused by sintering and removal of photosensitive resin melt, reduces the internal stress generated by shrinkage mismatch at the interface between layers, and reduces the driving force of interface weakness and cracking from the source.

[0060] (3) Enhanced interface densification: The tight particle packing and enhanced inter-particle contact brought about by the high solid content, combined with the possible influence of the lamellar crystals on the sintering process, help the interlayer interface to densify more effectively during sintering and reduce defects such as pores at the interface.

[0061] (4) Overall toughening: The flaky aluminum oxide crystals dispersed in the matrix themselves play a toughening role (crack deflection, pull-out, etc.). This toughening effect also exists in printed parts containing a large number of layered interfaces, improving the ability of the entire material (including the interface area) to resist damage.

[0062] Therefore, the flaky alumina reinforced ceramic core achieves three aspects in a synergistic manner by precisely controlling the solid-liquid volume ratio, the content of alumina precursor and the content of crystal modifier: forming an effective flaky crystal bridging structure between layers, minimizing the interlaminar shrinkage stress caused by resin burnout, and promoting good densification and bonding of the interlaminar interface. Through the combined effect of these three aspects, the number of weak areas of the laminar interface in the photocuring additive manufacturing ceramic core is significantly reduced, and the mechanical properties and reliability of the final ceramic core product are improved.

[0063] In some optional embodiments, the type of the aluminum oxide precursor includes at least one of the following: aluminum hydroxide, γ-Al2O3, ρ-Al2O3, δ-Al2O3 and boehmite; and / or

[0064] The crystal shape modifier includes at least one of the following: aluminum fluoride, calcium fluoride and magnesium fluoride.

[0065] In these embodiments, the use of at least one of aluminum hydroxide, γ-Al2O3, ρ-Al2O3, δ-Al2O3, and boehmite as an alumina precursor can form uniform and dispersed flaky alumina crystals under the control of a crystal shape modifier. These flaky alumina crystals can hinder the movement of interlayer cracks, improve the bonding strength between interfaces, and reduce the number of weak areas in the ceramic core. The use of at least one of aluminum fluoride, calcium fluoride, and magnesium fluoride as a crystal shape modifier can induce the alumina precursor to form a flaky morphology and inhibit the abnormal growth of alumina grains. At the same time, the size and distribution of the flaky alumina crystals can be controlled so that the flaky alumina crystals are evenly distributed between the interlayer interfaces, significantly reducing the number of weak areas at the layered interfaces and improving the mechanical properties and reliability of the final ceramic core product.

[0066] In some optional embodiments, the solid-phase mixed powder also includes a matrix ceramic powder and a sintering aid, the mass of the matrix ceramic powder is 85% to 95% of the total mass of the solid-phase mixed powder, and the mass of the sintering aid is 1% to 3% of the total mass of the solid-phase mixed powder.

[0067] In these embodiments, a base ceramic powder, comprising 85% to 95% of the total mass of the solid-phase mixed powder, can serve as the main skeleton of the solid-phase mixed powder, allowing the alumina precursor and the crystal form modifier to be uniformly dispersed within the main skeleton to enhance their interaction, effectively reducing the number of weak areas in the ceramic core and improving the mechanical properties of the formed ceramic core. Furthermore, a sintering aid, comprising 1% to 3% of the total mass of the solid-phase mixed powder, can enhance the forming properties of the solid-phase mixed powder during the sintering process, allowing the solid-phase mixed powder to form a uniformly distributed ceramic core.

[0068] The mass of the matrix ceramic powder can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94% or 95% of the total mass of the solid phase mixed powder.

[0069] The mass of the sintering aid can be 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.5% or 3.0% of the total mass of the solid phase mixed powder.

[0070] In some optional embodiments, the type of the matrix ceramic powder includes at least one of the following: silicon dioxide, aluminum oxide, calcium oxide and zircon; and / or

[0071] The sintering aid includes at least one of the following types: MgO, TiO2 and MnO2.

[0072] In these embodiments, a base ceramic powder comprising at least one of silica, alumina, calcia, and zircon serves as the main framework of the solid-phase mixed powder, accommodating and uniformly dispersing the alumina precursor and crystal form modifier, thereby enhancing their interaction and effectively reducing the number of weak areas in the ceramic core. Furthermore, a sintering aid comprising at least one of MgO, TiO2, and MnO2 effectively enhances the forming properties of the solid-phase mixed powder during sintering, allowing the solid-phase mixed powder to form a uniformly distributed ceramic core.

[0073] In some optional embodiments, the median particle size of the matrix ceramic powder is 0.5 μm to 20 μm; and / or

[0074] The median particle size of the aluminum oxide precursor is 0.5 μm to 5 μm; and / or

[0075] The median particle size of the crystal shape modifier is 0.2 μm to 1 μm; and / or

[0076] The median particle size of the sintering aid is 0.1 μm to 0.5 μm.

[0077] In these embodiments, the base ceramic powder with a median particle size of 0.5 μm to 20 μm can serve as the main skeleton of the solid-phase mixed powder, accommodating and uniformly dispersing the alumina precursor and the crystal form regulator to enhance the interaction between the two and effectively reduce the number of weak areas of the ceramic core; at the same time, the base ceramic powder can improve the mechanical properties of the ceramic core. In addition, the alumina precursor with a median particle size of 0.5 μm to 5 μm forms uniform and dispersed flaky alumina crystals under the regulation of the crystal form regulator. These flaky alumina crystals can hinder the movement of interlayer cracks and enhance the bonding strength between interfaces, thereby reducing the number of weak areas of the ceramic core. In addition, the crystal form regulator with a median particle size of 0.2 μm to 1 μm can induce the alumina precursor to form a flaky morphology and inhibit the abnormal growth of alumina grains. At the same time, the size and distribution of the flaky alumina crystals can be regulated so that the flaky alumina crystals can be evenly distributed between the interlayer interfaces, significantly reducing the number of weak areas of the layered interfaces and improving the mechanical properties and reliability of the final ceramic core product. In addition, the sintering aid with a median particle size of 0.1 μm to 0.5 μm can be effectively distributed in other solid-phase mixed powders, and in the subsequent sintering stage, it can promote the solid-phase mixed powders to form a uniformly distributed ceramic core.

[0078] The median particle size of the matrix ceramic powder may be 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, 5.0 μm, 10.0 μm, 15.0 μm or 20.0 μm.

[0079] The median particle size of the aluminum oxide precursor may be 0.5 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 3.5 μm, 4.0 μm, 4.5 μm, or 5.0 μm.

[0080] The median particle size of the crystal shape modifier may be 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1.0 μm.

[0081] The median particle size of the sintering aid may be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm.

[0082] In some optional embodiments, the photosensitive resin mixture includes an oligomer, a monomer diluent and a photoinitiator, the mass of the oligomer is 32% to 64% of the total mass of the photosensitive resin mixture, the mass of the monomer diluent is 35% to 65% of the total mass of the photosensitive resin mixture, and the mass of the photoinitiator is 1% to 3% of the total mass of the photosensitive resin mixture.

[0083] In these embodiments, oligomers comprising 32% to 64% of the total mass of the photosensitive resin mixture can serve as a resin backbone. During the stage of segmented photocuring 3D printing, these oligomers can form a cross-linked network, imparting mechanical strength to the solid-phase mixed powder. Furthermore, the oligomers can increase the viscosity of the ceramic slurry and slow down the sedimentation of the high-density matrix ceramic powder, thereby preventing interfacial weakening caused by interlayer component segregation, thereby reducing the number of weak areas in the ceramic core. Furthermore, a monomer diluent comprising 35% to 65% of the total mass of the photosensitive resin mixture can effectively reduce the viscosity of the ceramic slurry, imparting good fluidity to the matrix ceramic powder, improving the wettability of the interlayer interface, and improving the bonding strength of weak areas at the interlayer interface. Furthermore, the monomer diluent can form interconnected channels during the initial degreasing and sintering phase, promoting the formation and orderly discharge of pyrolysis gas from the photosensitive resin mixture, thereby ensuring the bonding strength of the interlayer interface. In addition, the photoinitiator, which accounts for 1% to 3% of the total mass of the photosensitive resin mixture, can match the scattering / absorption characteristics of the matrix ceramic powder to ultraviolet light, thereby improving the light penetration of segmented light-curing 3D printing and promoting the effective curing of segmented light-curing 3D printing; at the same time, the small addition of photoinitiator can also reduce the generation of fluorine-containing / phosphorus-containing by-products during the degreasing and sintering process, thereby ensuring the purity and mechanical properties of the sintered body.

[0084] The mass of the oligomer can be 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 54%, 58%, 62% or 64% of the total mass of the photosensitive resin mixture.

[0085] The mass of the monomer diluent can be 35%, 40%, 45%, 50%, 55%, 60% or 65% of the total mass of the photosensitive resin mixture.

[0086] The mass of the photoinitiator can be 1.0%, 1.5%, 2.0%, 2.5% or 3.0% of the total mass of the photosensitive resin mixture.

[0087] It should be noted that the photosensitive resin mixture can be formed through the interaction between the oligomer, the monomer diluent and the photoinitiator. The specific mechanism is shown in Table 1.

[0088] Table 1 Interactions between photosensitive resin mixtures

[0089]

[0090] The photosensitive resin mixture achieves the unity of "high solid content slurry printability", "green body structural integrity" and "degreasing process safety" through the process of: oligomer to determine the skeleton → monomer to adjust the rheology → initiator to control the reaction, ultimately ensuring that the interlayer bridging effect of flaky alumina is fully exerted, significantly reducing the number of weak areas at the layered interface of the ceramic core.

[0091] In some optional embodiments, the type of the oligomer includes at least one of the following: epoxy acrylate, polyurethane acrylate and silicone polyurethane acrylate; and / or

[0092] The monomer diluent comprises at least one of the following: 1,6-hexanediol diacrylate, isobornyl acrylate, dipropylene glycol diacrylate and trimethylolpropane triacrylate; and / or

[0093] The photoinitiator comprises at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester and 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide.

[0094] In these embodiments, the use of an oligomer comprising at least one of epoxy acrylate, polyurethane acrylate, and silicone polyurethane acrylate can form a cross-linked network, imparting mechanical strength to the solid-phase mixed powder. The oligomer can also increase the viscosity of the ceramic slurry, thereby preventing interfacial weakening caused by interlayer component segregation, thereby reducing the number of weak areas in the ceramic core. Furthermore, the use of a monomer diluent comprising at least one of 1,6-hexanediol diacrylate, isobornyl acrylate, dipropylene glycol diacrylate, and trimethylolpropane triacrylate can impart good fluidity to the matrix ceramic powder, enhance the wettability of the interlayer interface, and improve the bonding strength of weak areas at the interlayer interface. In addition, the use of photoinitiators including 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester and 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide can match the scattering / absorption characteristics of the matrix ceramic powder to ultraviolet light, promote the effective curing of segmented light-curing 3D printing, and ensure the purity and mechanical properties of the sintered body.

[0095] Figure 2 A schematic flow chart of a method for preparing a flaky alumina reinforced ceramic core provided in an embodiment of the present application is shown as an example;

[0096] Figure 3 The following is a schematic diagram showing an actual process of a method for preparing a flaky alumina reinforced ceramic core provided in an embodiment of the present application;

[0097] Based on a general inventive concept, such as Figure 2 and Figure 3 As shown, the embodiment of the present application provides a method for preparing the flaky alumina reinforced ceramic core, the method comprising:

[0098] S1. The solid phase mixed powder, photosensitive resin mixture and dispersant are mixed to obtain a ceramic paste;

[0099] S2. The ceramic paste is subjected to light-curing 3D printing to obtain a ceramic core body;

[0100] S3. Degreasing and sintering the ceramic core blank in sequence to obtain an alumina reinforced ceramic core.

[0101] This method is a preparation method based on the above-mentioned flaky alumina reinforced ceramic core. The specific composition of the flaky alumina reinforced ceramic core can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0102] It should be noted that the solid-phase mixed powder can be prepared by dry ball milling the base ceramic powder, the alumina precursor, the crystal shape modifier, and the sintering aid to obtain a mixture; then, sieving the mixture to obtain the solid-phase mixed powder. The dry ball milling speed can be 400 r / min, and the dry ball milling time can be 4 hours. The dry ball milling can be performed in a polytetrafluoroethylene ball mill, and the grinding balls used in the dry ball milling can be made of alumina.

[0103] It should be noted that the dispersant may be KOS110 coupling agent, silane coupling agent KH570, BYK DISPERBYK-111 wetting and dispersing agent, oleic acid, or propylene glycol methyl ether PM1590. The mass of the dispersant may be 0.5% to 4.0% of the mass of the solid phase mixed powder.

[0104] It should be noted that the mixing can be performed under vacuum conditions.

[0105] It should be noted that the volume of the solid phase powder in the ceramic paste is more than 45% of the total volume of the ceramic paste. Further, the volume of the solid phase powder in the ceramic paste is 50% to 55% of the total volume of the ceramic paste.

[0106] It should be noted that the parameters of the segmented light-curing 3D printing can be: the thickness of a single cured layer can generally be 25μm to 100μm, preferably 50μm; the curing power density can generally be 10mW / cm 2 Up to 40mW / cm 2 , preferably 20mW / cm 2 Up to 30mW / cm 2 The exposure time of a single layer can generally be 1s to 6s, preferably 2s to 4s; the wavelength of the laser can be 405nm.

[0107] In some optional embodiments, the degreasing process includes a first degreasing stage, a second degreasing stage and a third degreasing stage, the temperature of the first degreasing stage is 200° C. to 350° C., the heating rate of the first degreasing stage is 0.2° C. / min to 2° C. / min, and the duration of the first degreasing stage is 60 min to 240 min; and / or

[0108] The temperature of the second degreasing section is 380° C. to 450° C., the heating rate of the second degreasing section is 0.2° C. / min to 2° C. / min, and the duration of the second degreasing section is 60 min to 180 min; and / or

[0109] The temperature of the third degreasing section is 550° C. to 650° C., the heating rate of the third degreasing section is 0.2° C. / min to 5° C. / min, and the duration of the third degreasing section is 120 min to 240 min.

[0110] In these embodiments, the first degreasing stage with a temperature of 200°C to 350°C, a heating rate of 0.2°C / min to 2°C / min, and a duration of 60min to 240min can initially remove small molecules and maintain the structural skeleton of the solid-phase mixed powder, forming micropores to facilitate the subsequent second degreasing stage. In addition, the second degreasing stage with a temperature of 380°C to 450°C, a heating rate of 0.2°C / min to 2°C / min, and a duration of 60min to 180min can cause the oligomers in the photosensitive resin mixture to exhibit a step-by-step decomposition, which cooperates with the micropores formed in the first degreasing stage to form a gas diffusion network, thereby preventing the collapse of the skeleton of the solid-phase mixed powder and allowing the ceramic core to be initially solidified and formed. In addition, the third degreasing stage with a temperature of 550°C to 650°C, a heating rate of 0.2°C / min to 5°C / min, and a duration of 120min to 240min can activate the crystal modifier, induce the heterogeneous nucleation of flake-like α-Al2O3, and promote the directional growth of the formed flake-like alumina crystal phase, so that the flake-like alumina crystal phase has sufficient length to span the layer interface and promote bridging between the two interlayer interfaces.

[0111] The temperature of the first degreasing stage may be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 300°C or 350°C.

[0112] The heating rate of the first degreasing stage may be 0.2°C / min, 0.3°C / min, 0.4°C / min, 0.5°C / min, 1.0°C / min, 1.5°C / min or 2.0°C / min.

[0113] The duration of the first degreasing stage may be 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 180 min, 200 min, 220 min or 240 min.

[0114] The temperature of the second degreasing stage may be 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C.

[0115] The heating rate of the second degreasing stage may be 0.2°C / min, 0.3°C / min, 0.4°C / min, 0.5°C / min, 1.0°C / min, 1.5°C / min or 2.0°C / min.

[0116] The duration of the second degreasing stage may be 60 min, 80 min, 100 min, 120 min, 140 min, 160 min, 160 min or 180 min.

[0117] The temperature of the third degreasing section may be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C or 650°C.

[0118] The heating rate of the third degreasing section can be 0.2℃ / min, 0.3℃ / min, 0.4℃ / min, 0.5℃ / min, 1.0℃ / min, 1.5℃ / min, 2.0℃ / min, 2.5℃ / min, 3.0℃ / min, 3.5℃ / min, 4.0℃ / min, 4.5℃ / min or 5.0℃ / min.

[0119] The duration of the third degreasing stage may be 120 min, 140 min, 160 min, 180 min, 200 min, 220 min or 240 min.

[0120] In some optional embodiments, the temperature of the sintering process is 1400° C. to 1600° C., the heating rate of the sintering process is 2° C. / min to 5° C. / min, and the duration of the sintering process is 120 min to 300 min.

[0121] In these embodiments, a sintering treatment with a temperature of 1400°C to 1600°C, a heating rate of 2°C / min to 5°C / min, and a duration of 120min to 300min can precisely control the balance between densification kinetics and grain growth, significantly improving the interlayer bonding strength and overall performance of flaky alumina-reinforced ceramics.

[0122] The temperature of the sintering process may be 1400°C, 1410°C, 1420°C, 1430°C, 1440°C, 1450°C, 1500°C, 1550°C or 1600°C.

[0123] The heating rate of the sintering process can be 2°C / min, 2.5°C / min, 3.0°C / min, 3.5°C / min, 4.0°C / min, 4.5°C / min or 5.0°C / min.

[0124] The duration of the sintering process may be 120 min, 140 min, 160 min, 180 min, 200 min, 220 min, 240 min, 260 min, 280 min or 300 min.

[0125] It should be noted that the specific mechanism of the sintering process is as follows:

[0126] 1. Reasonable setting of temperature range:

[0127] Using a temperature setting of 1400°C to 1500°C can promote the neck formation and diffusion mass transfer of alumina particles, and activate the volume diffusion of solid-phase mixed powder to achieve rapid densification of the matrix; using a temperature setting of 1500°C to 1600°C can promote the directional growth and interface fusion of flake α-Al2O3, and promote the growth of flake alumina crystals across the interlayer interface to form a "rivet-type" reinforcement structure.

[0128] (1) Alumina sintering window matching: The theoretical densification temperature of α-Al2O3 is 1450℃ to 1650℃, and the temperature range of 1400℃ to 1600℃ perfectly covers its sintering activity range, avoiding insufficient densification at low temperature (<1400℃) or abnormal grain growth at high temperature (>1600℃).

[0129] (2) Synergistic effect of crystal modifiers: Regulators such as magnesium fluoride (MgF2) will be completely vaporized at a sintering temperature of ≥1400°C. Gas phase transmission will promote the preferential growth of flake alumina on the crystal plane and improve the aspect ratio of flake alumina.

[0130] 2. Optimization design of heating rate (2℃ / min to 5℃ / min)

[0131] At a heating rate of 2°C / min to 3°C / min, the sintering process maintains a uniform heat conduction state, eliminating the temperature difference between the inside and outside of thick-walled components and preventing thermal stress cracking at the interlayer interface. At a heating rate of 7°C / min to 5°C / min, the sintering process can suppress surface pre-sintering, prevent premature closure of the surface of the ceramic core, and ensure the discharge of internal gases during the sintering process.

[0132] (1) Densification gradient control: Slow heating rate can make the ceramic core body shrink synchronously from the surface to the core, reducing interlayer microcracks caused by shrinkage differences.

[0133] (2) Directed discharge of residual pores: The heating rate of 2°C / min to 5°C / min matches the critical transition rate of open pores to closed pores in the ceramic core, avoiding the premature formation of closed pores that lock the gas in the interlayer interface.

[0134] 3. Dynamic balance of holding time (120min to 300min)

[0135] When the holding time is between 120 and 180 minutes, the ceramic core blank is fully densified, effectively increasing the Vickers hardness of the ceramic core blank. When the holding time is between 180 and 300 minutes, the lamellar aluminum oxide crystals bridge the interlayer interface and develop, thereby increasing the shear strength between the layers.

[0136] Directional growth window of flake crystals: When the holding time is more than 180 minutes, the flake α-Al2O3 grows vertically between layers and can span two adjacent printed layers, thereby achieving physical bridging of the interlayer interface.

[0137] 4. Mechanism of strengthening the layered interface:

[0138] (1) Eliminate interface pores and microcracks:

[0139] The slow heating rate (2°C / min to 5°C / min) + high temperature holding temperature (1400°C to 1600°C) makes the density of the interlayer region consistent with that within the layer (density difference <0.3%), and the interface porosity is reduced to below 0.5%.

[0140] (2) Interlayer riveting effect of lamellar crystals:

[0141] 1) Crack deflection: When the crack propagates along the interface, it is forced to detour around the lamellar crystal, which prolongs the path and consumes energy;

[0142] 2) Mechanical interlocking: The plate-like crystals are embedded in the upper and lower matrix to form a complex bridge structure.

[0143] (3) Homogenization of alumina grain size:

[0144] The upper limit of the holding time of 300 min can avoid excessive growth of alumina grains and ensure that the mechanical properties of the interface area of ​​the ceramic core match those of the matrix.

[0145] 5. Trinity Strengthening Mechanism: This debinding and sintering process achieves this through temperature-time synergistic densification, coupled heating rate and gas expulsion, and matching holding period and crystal growth: near-zero interlayer porosity and microcracks, maximized directional bridging of zero-flaky alumina, and uniform grain size across the entire cross-section. Ultimately, the interlayer interface is transformed from a "weak zone" to a "strengthened zone," effectively breaking through the interlayer performance bottleneck in light-curing ceramic additive manufacturing.

[0146] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0147] Example 1

[0148] like Figure 1 As shown, a flaky alumina reinforced ceramic core, the raw materials of the medium-sized flaky alumina reinforced ceramic core include: a solid-phase mixed powder and a photosensitive resin mixed liquid, the volume V1 of the solid-phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=45:55; the alumina precursor includes an alumina precursor and a crystal shape regulator, the mass of the alumina precursor is 6% of the total mass of the alumina precursor, and the mass of the crystal shape regulator is 2% of the total mass of the alumina precursor.

[0149] The type of alumina precursor is aluminum hydroxide;

[0150] The type of crystal shape modifier is aluminum fluoride.

[0151] The alumina precursor further includes a base ceramic powder and a sintering aid. The mass of the base ceramic powder accounts for 90% of the total mass of the alumina precursor, and the mass of the sintering aid accounts for 1% of the total mass of the alumina precursor.

[0152] The type of base ceramic powder is silicon dioxide;

[0153] The type of sintering aid is MgO.

[0154] The median particle size of the matrix ceramic powder is 5 μm;

[0155] The median particle size of the alumina precursor is 2.0 μm;

[0156] The median particle size of the crystal shape modifier is 0.6 μm;

[0157] The median particle size of the sintering aid is 0.3 μm.

[0158] The photosensitive resin mixture includes oligomers, monomer diluents and photoinitiators. The mass of the oligomers is 35% of the total mass of the photosensitive resin mixture, the mass of the monomer diluents is 64% of the total mass of the photosensitive resin mixture, and the mass of the photoinitiator is 1% of the total mass of the photosensitive resin mixture.

[0159] The type of oligomer is polyurethane acrylate;

[0160] The type of monomer diluent is 1,6-hexanediol diacrylate;

[0161] The type of photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0162] like Figure 2 and Figure 3 As shown, a method for preparing a flaky alumina reinforced ceramic core comprises:

[0163] S1. The solid phase mixed powder, the photosensitive resin mixture and the dispersant DISPERBYK-111 are mixed to obtain a ceramic paste; the mass of the dispersant is 2% of the mass of the solid phase mixed powder;

[0164] S2. The ceramic paste is subjected to light-curing 3D printing to obtain a ceramic core blank; the parameters of the segmented light-curing 3D printing are: a single layer thickness of 50 μm; a curing power density of 20 mW / cm 2 The exposure time of a single layer is 3 s; the wavelength of the laser is 405 nm;

[0165] S3. Degreasing and sintering the ceramic core blank in sequence to obtain an alumina reinforced ceramic core.

[0166] The degreasing process includes the first degreasing stage, the second degreasing stage and the third degreasing stage. The temperature of the first degreasing stage is 280℃.

[0167] The heating rate of the first degreasing stage was 0.5°C / min, and the duration of the first degreasing stage was 90 min;

[0168] The temperature of the second degreasing stage is 400° C., the heating rate of the second degreasing stage is 1.0° C. / min, and the duration of the second degreasing stage is 60 min to 180 min;

[0169] The temperature of the third degreasing stage is 600° C., the heating rate of the third degreasing stage is 0.5° C. / min, and the duration of the third degreasing stage is 180 min.

[0170] The sintering temperature is 1450° C., the heating rate is 2° C. / min, and the sintering duration is 150 min.

[0171] Example 2

[0172] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0173] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=52:48; the alumina precursor includes an alumina precursor and a crystal modifier, the mass of the alumina precursor is 8% of the total mass of the alumina precursor, and the mass of the crystal modifier is 2% of the total mass of the alumina precursor.

[0174] The type of alumina precursor is ρ-Al2O3.

[0175] The type of crystal shape modifier is aluminum fluoride.

[0176] The mass of the base ceramic powder is 88% of the total mass of the alumina precursor, and the mass of the sintering aid is 2% of the total mass of the alumina precursor.

[0177] The type of matrix ceramic powder is α-Al2O3;

[0178] The type of sintering aid is MgO.

[0179] The median particle size of the matrix ceramic powder is 8 μm;

[0180] The median particle size of the alumina precursor is 2 μm;

[0181] The median particle size of the crystal shape modifier is 0.6 μm;

[0182] The median particle size of the sintering aid is 0.3 μm.

[0183] The mass of the oligomer is 35% of the total mass of the photosensitive resin mixed liquid, the mass of the monomer diluent is 64% of the total mass of the photosensitive resin mixed liquid, and the mass of the photoinitiator is 1% of the total mass of the photosensitive resin mixed liquid.

[0184] The type of oligomer is polyurethane acrylate;

[0185] The type of monomer diluent is 1,6-hexanediol diacrylate;

[0186] The photoinitiator includes at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0187] The temperature of the first degreasing stage is 280°C, the heating rate of the first degreasing stage is 0.5°C / min, and the duration of the first degreasing stage is 90 min;

[0188] The temperature of the second degreasing stage is 400°C, the heating rate of the second degreasing stage is 1°C / min, and the duration of the second degreasing stage is 150 min;

[0189] The temperature of the third degreasing stage is 600° C., the heating rate of the third degreasing stage is 0.5° C. / min, and the duration of the third degreasing stage is 180 min.

[0190] The sintering temperature is 1450° C., the heating rate is 2° C. / min, and the sintering duration is 150 min.

[0191] Example 3

[0192] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0193] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=60:40; the alumina precursor includes an alumina precursor and a crystal modifier, the mass of the alumina precursor is 7% of the total mass of the alumina precursor, and the mass of the crystal modifier is 2% of the total mass of the alumina precursor.

[0194] The type of alumina precursor is ρ-Al2O3.

[0195] The type of crystal shape modifier is aluminum fluoride.

[0196] The mass of the base ceramic powder is 90% of the total mass of the alumina precursor, and the mass of the sintering aid is 1% of the total mass of the alumina precursor.

[0197] The type of base ceramic powder is silicon dioxide;

[0198] The type of sintering aid is MgO.

[0199] The median particle size of the matrix ceramic powder is 5 μm;

[0200] The median particle size of the alumina precursor is 2 μm;

[0201] The median particle size of the crystal shape modifier is 0.6 μm;

[0202] The median particle size of the sintering aid is 0.3 μm.

[0203] The mass of the oligomer is 35% of the total mass of the photosensitive resin mixed liquid, the mass of the monomer diluent is 64% of the total mass of the photosensitive resin mixed liquid, and the mass of the photoinitiator is 1% of the total mass of the photosensitive resin mixed liquid.

[0204] The type of oligomer is polyurethane acrylate;

[0205] The type of monomer diluent is 1,6-hexanediol diacrylate;

[0206] The type of photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0207] The temperature of the first degreasing stage is 280°C, the heating rate of the first degreasing stage is 0.5°C / min, and the duration of the first degreasing stage is 90 min;

[0208] The temperature of the second degreasing stage is 400°C, the heating rate of the second degreasing stage is 1°C / min, and the duration of the second degreasing stage is 150 min;

[0209] The temperature of the third degreasing stage is 600° C., the heating rate of the third degreasing stage is 0.5° C. / min, and the duration of the third degreasing stage is 180 min.

[0210] The sintering temperature is 1450° C., the heating rate is 2° C. / min, and the sintering duration is 150 min.

[0211] Example 4

[0212] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0213] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=55:45; the alumina precursor includes an alumina precursor and a crystal modifier, the mass of the alumina precursor is 7% of the total mass of the alumina precursor, and the mass of the crystal modifier is 2% of the total mass of the alumina precursor.

[0214] The type of alumina precursor is ρ-Al2O3.

[0215] The type of crystal shape modifier is aluminum fluoride.

[0216] The mass of the base ceramic powder is 90% of the total mass of the alumina precursor, and the mass of the sintering aid is 1% of the total mass of the alumina precursor.

[0217] The type of base ceramic powder is silicon dioxide;

[0218] The type of sintering aid is MgO.

[0219] The median particle size of the matrix ceramic powder is 5 μm;

[0220] The median particle size of the alumina precursor is 2 μm;

[0221] The median particle size of the crystal shape modifier is 0.6 μm;

[0222] The median particle size of the sintering aid is 0.3 μm.

[0223] The mass of the oligomer is 35% of the total mass of the photosensitive resin mixed liquid, the mass of the monomer diluent is 64% of the total mass of the photosensitive resin mixed liquid, and the mass of the photoinitiator is 1% of the total mass of the photosensitive resin mixed liquid.

[0224] The type of oligomer is polyurethane acrylate;

[0225] The type of monomer diluent is 1,6-hexanediol diacrylate;

[0226] The type of photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0227] The temperature of the first degreasing stage is 280°C, the heating rate of the first degreasing stage is 0.5°C / min, and the duration of the first degreasing stage is 90 min;

[0228] The temperature of the second degreasing stage is 400°C, the heating rate of the second degreasing stage is 1°C / min, and the duration of the second degreasing stage is 150 min;

[0229] The temperature of the third degreasing stage is 600° C., the heating rate of the third degreasing stage is 0.5° C. / min, and the duration of the third degreasing stage is 180 min.

[0230] The sintering temperature is 1450° C., the heating rate is 2° C. / min, and the sintering duration is 150 min.

[0231] Example 5

[0232] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0233] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=52:48; the alumina precursor includes an alumina precursor and a crystal modifier, the mass of the alumina precursor is 7% of the total mass of the alumina precursor, and the mass of the crystal modifier is 2% of the total mass of the alumina precursor.

[0234] The type of alumina precursor is aluminum hydroxide.

[0235] The type of crystal shape modifier is aluminum fluoride.

[0236] The mass of the base ceramic powder is 90% of the total mass of the alumina precursor, and the mass of the sintering aid is 1% of the total mass of the alumina precursor.

[0237] The type of base ceramic powder is silicon dioxide;

[0238] The type of sintering aid is MgO.

[0239] The median particle size of the matrix ceramic powder is 5 μm;

[0240] The median particle size of the alumina precursor is 2 μm;

[0241] The median particle size of the crystal shape modifier is 0.6 μm;

[0242] The median particle size of the sintering aid is 0.3 μm.

[0243] The mass of the oligomer is 35% of the total mass of the photosensitive resin mixed liquid, the mass of the monomer diluent is 64% of the total mass of the photosensitive resin mixed liquid, and the mass of the photoinitiator is 1% of the total mass of the photosensitive resin mixed liquid.

[0244] The type of oligomer is polyurethane acrylate;

[0245] The type of monomer diluent is 1,6-hexanediol diacrylate;

[0246] The type of photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0247] The temperature of the first degreasing stage is 280°C, the heating rate of the first degreasing stage is 0.5°C / min, and the duration of the first degreasing stage is 90 min;

[0248] The temperature of the second degreasing stage is 400°C, the heating rate of the second degreasing stage is 1°C / min, and the duration of the second degreasing stage is 150 min;

[0249] The temperature of the third degreasing stage is 600° C., the heating rate of the third degreasing stage is 0.5° C. / min, and the duration of the third degreasing stage is 180 min.

[0250] The sintering temperature is 1450° C., the heating rate is 2° C. / min, and the sintering duration is 150 min.

[0251] Comparative Example 1

[0252] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0253] No alumina precursor and crystal shape regulator are added.

[0254] Comparative Example 2

[0255] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0256] The alumina-based ceramic core blank is first degreased and pre-sintered, and then subjected to a secondary high-temperature sintering treatment; the preferred degreasing and pre-sintering process is: heating to 280°C at 0.5°C / min and keeping warm for 90 minutes, heating to 400°C at 1°C / min and keeping warm for 150 minutes, heating to 600°C at 0.5°C / min and keeping warm for 120 minutes, heating to 1100°C at 2°C / min and keeping warm for 120 minutes, and finally heating to 1450°C at 2°C / min for high-temperature sintering and keeping warm for 120 minutes, so that the alumina precursor and the crystal shape regulator form whisker-like alumina instead of flaky alumina.

[0257] Comparative Example 3

[0258] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0259] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=30:70.

[0260] Comparative Example 4

[0261] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0262] The volume V1 of the solid phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=70:30.

[0263] Comparative Example 5

[0264] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0265] The degreasing treatment is directly carried out under the conditions of the third degreasing stage.

[0266] Related experiments and effect data:

[0267] The ceramic core of Example 2 was collected and its cross section was observed under a scanning electron microscope. The results are as follows: Figure 1 As shown in the figure, the interlayer interfaces of the ceramic core are evenly distributed, and the flaky aluminum oxide crystals are distributed in a bridge-like manner at the interfaces between the layers.

[0268] The ceramic core products of each embodiment and comparative example were collected and their shrinkage, porosity, flexural strength and other properties were statistically analyzed. The results are shown in Table 2.

[0269] Table 2 Distribution of shrinkage, porosity and flexural strength of ceramic core products of various embodiments and comparative examples

[0270]

[0271] As can be seen from Table 1, the embodiment of the present application provides a flaky alumina reinforced ceramic core. The flaky alumina reinforced ceramic core, through high solid content design, the introduction and regulation of flaky alumina, and the action of a crystal modifier, synergistically reduces the number of weak areas of the laminar interface generated in the photocuring additive manufacturing process of the ceramic core, so that the shrinkage rate of the ceramic core can be controlled below 9%, the porosity can be controlled below 35%, and the flexural strength can be controlled within 30 MPa to 40 MPa.

[0272] Compared with Example 1, Comparative Example 1 does not use an alumina precursor and a crystal shape regulator, and ultimately it is difficult to form flaky alumina at the interlayer interface, resulting in affected performance of the ceramic core.

[0273] Compared with Example 1, Comparative Example 2 forms non-flaky aluminum oxide crystals, such as whisker aluminum oxide, which results in limited improvement in the bonding strength of the interlayer interface and is difficult to meet actual use requirements.

[0274] Compared to Example 1, Comparative Example 3 used too much photosensitive resin mixed liquid. This resulted in the ceramic core being able to form during the degreasing and sintering stages, but the mechanical properties of the ceramic core were not satisfactory. Comparative Example 4 used too much solid-phase mixed powder, which easily agglomerated the ceramic core during the molding stage, making it difficult to form the ceramic core.

[0275] Compared with Example 1, Comparative Example 5 does not perform step-by-step treatment during the degreasing stage, but is directly carried out under the conditions of the third degreasing stage. This causes the photosensitive resin mixture to be quickly removed from the ceramic core blank, resulting in a large number of voids in the ceramic core, affecting the mechanical properties of the ceramic core.

[0276] In summary, the embodiments of the present application provide a flaky alumina reinforced ceramic core, which synergistically reduces the number of weak areas of the layered interface generated in the photocuring additive manufacturing process of the ceramic core through a high solid content design, the introduction and regulation of flaky alumina, and the action of a crystal modifier.

[0277] In addition, an embodiment of the present application provides a flaky alumina reinforced ceramic core, which can improve the viscosity and curing effect of the ceramic slurry by controlling the volume ratio of the solid-phase mixed powder and the photosensitive resin mixture, effectively avoiding the addition of one-dimensional (whiskers or fibers) or two-dimensional (flaky) reinforcing phases, thereby reducing the influence of the solid content of the ceramic slurry.

[0278] In addition, an embodiment of the present application provides a method for preparing a flaky alumina reinforced ceramic core. The preparation method has a simple process, the in-situ synthesized flaky alumina has good dispersion, and the bonding strength between the flaky alumina crystal phase and the matrix ceramic powder is high, which has a significant strengthening effect on the performance of the ceramic core, especially the weak areas of the interlayer interface bonding.

[0279] In addition, the preparation method of a flaky alumina reinforced ceramic core provided in the embodiments of the present application can be applied to the development and application of ceramic cores of other systems.

[0280] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A flaky alumina reinforced ceramic core, the raw materials of which include: A solid-phase mixed powder and a photosensitive resin mixed liquid, wherein the volume V1 of the solid-phase mixed powder and the volume V2 of the photosensitive resin mixed liquid satisfy: V1:V2=(45 to 60):(40 to 55); the solid-phase mixed powder includes an alumina precursor and a crystal form regulator, the mass of the alumina precursor is 2% to 8% of the total mass of the solid-phase mixed powder, and the mass of the crystal form regulator is 2% to 4% of the total mass of the solid-phase mixed powder.

2. The flaky alumina reinforced ceramic core according to claim 1, characterized in that: The type of the aluminum oxide precursor includes at least one of the following: aluminum hydroxide, γ-Al2O3, ρ-Al2O3, δ-Al2O3 and boehmite; and / or The crystal shape modifier includes at least one of the following: aluminum fluoride, calcium fluoride and magnesium fluoride.

3. The flaky alumina reinforced ceramic core according to claim 1, characterized in that: The solid-phase mixed powder further comprises a base ceramic powder and a sintering aid, wherein the mass of the base ceramic powder is 85% to 95% of the total mass of the solid-phase mixed powder, and the mass of the sintering aid is 1% to 3% of the total mass of the solid-phase mixed powder.

4. The flaky alumina reinforced ceramic core according to claim 3, characterized in that: The type of the matrix ceramic powder includes at least one of the following: silicon dioxide, aluminum oxide, calcium oxide and zircon; and / or The sintering aid includes at least one of the following types: MgO, TiO2 and MnO2.

5. The flaky alumina reinforced ceramic core according to claim 4, characterized in that: The median particle size of the matrix ceramic powder is 0.5 μm to 20 μm; and / or The median particle size of the aluminum oxide precursor is 0.5 μm to 5 μm; and / or The median particle size of the crystal shape modifier is 0.2 μm to 1 μm; and / or The median particle size of the sintering aid is 0.1 μm to 0.5 μm.

6. The flaky alumina reinforced ceramic core according to claim 1, characterized in that: The photosensitive resin mixture includes an oligomer, a monomer diluent and a photoinitiator, the mass of the oligomer is 32% to 64% of the total mass of the photosensitive resin mixture, the mass of the monomer diluent is 35% to 65% of the total mass of the photosensitive resin mixture, and the mass of the photoinitiator is 1% to 3% of the total mass of the photosensitive resin mixture.

7. The flaky alumina reinforced ceramic core according to claim 6, characterized in that: The type of the oligomer includes at least one of the following: epoxy acrylate, polyurethane acrylate and silicone polyurethane acrylate; and / or The monomer diluent comprises at least one of the following: 1,6-hexanediol diacrylate, isobornyl acrylate, dipropylene glycol diacrylate and trimethylolpropane triacrylate; and / or The photoinitiator comprises at least one of the following: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester and 2,4,6-trimethylbenzoyl-di(p-tolyl)phosphine oxide.

8. A method for preparing the flaky alumina reinforced ceramic core according to any one of claims 1 to 7, the method comprising: Mixing the solid phase mixed powder, the photosensitive resin mixed liquid and the dispersant to obtain a ceramic paste; Performing photocuring 3D printing on the ceramic paste to obtain a ceramic core blank; The ceramic core blank is subjected to degreasing treatment and sintering treatment in sequence to obtain an alumina reinforced ceramic core.

9. The method according to claim 8, characterized in that The degreasing process includes a first degreasing stage, a second degreasing stage and a third degreasing stage, the temperature of the first degreasing stage is 200° C. to 350° C., the heating rate of the first degreasing stage is 0.2° C. / min to 2° C. / min, and the duration of the first degreasing stage is 60 min to 240 min; and / or The temperature of the second degreasing section is 380° C. to 450° C., the heating rate of the second degreasing section is 0.2° C. / min to 2° C. / min, and the duration of the second degreasing section is 60 min to 180 min; and / or The temperature of the third degreasing section is 550° C. to 650° C., the heating rate of the third degreasing section is 0.2° C. / min to 5° C. / min, and the duration of the third degreasing section is 120 min to 240 min.

10. The method according to claim 8, characterized in that The temperature of the sintering process is 1400° C. to 1600° C., the heating rate of the sintering process is 2° C. / min to 5° C. / min, and the duration of the sintering process is 120 min to 300 min.

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