An aluminum nitride ceramic part and its molding method

Abstract

The application discloses an aluminum nitride ceramic part and a forming method thereof. The forming method comprises the following steps: mixing aluminum nitride ceramic powder and sintering aid powder to obtain solid mixed powder, then performing ball milling treatment, adding a first metering dispersant during the ball milling, adding the ball-milled solid mixed powder into a photocuring premix under light-proof conditions, adding a second metering dispersant, and continuously performing ball milling to prepare slurry; the aluminum nitride ceramic powder is continuously graded in three sizes; then printing, solidification, degreasing and sintering are performed to prepare the aluminum nitride ceramic part. The method uses three kinds of particle size graded aluminum nitride ceramic powder mixed with sintering aid powder to perform sintering treatment, which ensures the sintering density of the aluminum nitride ceramic and effectively improves the solidification depth. In addition, in the preparation of the photocuring premix, a high-refractive aid is added to reduce the refractive index difference between the aid and the powder, and the solidification penetration of the slurry is further improved.

Description

Technical Field

[0001] This invention belongs to the field of aluminum nitride ceramic parts manufacturing technology, and relates to an aluminum nitride ceramic part and its forming method. Background Technology

[0002] With the increasing demands for high power dissipation in aerospace and other intelligent power systems, aluminum nitride ceramics have become an important new packaging material for high-temperature, high-power radio frequency packaging applications. Aluminum nitride ceramics possess high thermal conductivity, low dielectric constant, a coefficient of thermal expansion matching that of silicon, high resistance, and low density, making them ideal substrates and packaging materials for large-scale integrated circuits.

[0003] To obtain aluminum nitride ceramic preforms with uniform internal structure and high density, the fabrication process becomes the most crucial step. This is because forming technology largely determines the uniformity of the preform and the ability to fabricate complex shapes, directly impacting the reliability of the ceramic material and the manufacturing efficiency and cost of ceramic components. Currently, traditional forming techniques for aluminum nitride ceramics mainly include dry pressing, tape casting, injection molding, and isostatic pressing. For aluminum nitride parts with complex structures, traditional processing methods often rely on molds or subtractive manufacturing, significantly increasing the processing cycle and cost, thus limiting the development and application of aluminum nitride ceramics. Compared to traditional forming methods, additive manufacturing offers advantages such as high precision, high production efficiency, short production cycle, and the ability to manufacture complex materials, truly enabling "free manufacturing" of parts and facilitating the widespread application of complex ceramic structures. Currently, common additive manufacturing technologies include stereolithography (SLA), diffuse profiling (DLP), fused deposition modeling (FDM), selective laser sintering (SLS), layered solid fabrication (LOM), and selective laser melting (SLM). Among them, DLP technology boasts high precision, high forming efficiency, and wide application, showing great potential in ceramic additive manufacturing. Currently, research on AlN ceramics using DLP technology mainly focuses on the selection of dispersants, curing characteristics, debinding, and sintering parameters. Duan et al. used an AlN slurry with a solids loading of 55 vol% to manufacture high-density complex parts. They investigated the effect on sintering temperature, finding that as the temperature increased from 1780℃ to 1845℃, the density of AlN ceramics increased from 2.67 g / cm³. 3 Increased to 3.20 g / cm³ 3The porosity was reduced from 20% to 4%, thereby increasing the thermal conductivity from 82 W / (m·K) to 155 W / (m·K). Lin et al. modified the surface of AlN powder with oleic acid to obtain an AlN ceramic suspension with a solid loading of 50 vol%. Furthermore, they found that the particle size of the ceramic powder is a key factor affecting the viscosity of the suspension. However, in current DLP molding technology for AlN ceramics, the curing depth is limited, and deep-layer additives often exhibit incomplete polymerization. Beyond a certain depth, the degree of monomer polymerization is extremely low, resulting in very low additive strength, which in turn affects the performance of the parts. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an aluminum nitride ceramic part and its forming method, thereby solving the technical problem of limited curing penetration depth of AlN ceramics manufactured using DLP technology in the prior art.

[0005] This invention is achieved through the following technical solution:

[0006] A method for forming aluminum nitride ceramic parts includes the following steps:

[0007] S1: Aluminum nitride ceramic powder and sintering aid powder are mixed to obtain a solid mixed powder, which is then ball-milled. During ball milling, a first metering dispersant is added. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a gradation of three particle sizes.

[0008] S2: Based on the three-dimensional model of the part, the slurry is used to print layer by layer, and ultraviolet light is used to cure it to obtain an aluminum nitride ceramic blank.

[0009] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0010] Preferably, the aluminum nitride ceramic powder is a gradation of aluminum nitride ceramic powder with particle sizes of 10μm, 2μm and 500nm; the mass ratio of the 10μm, 2μm and 500nm aluminum nitride ceramic powder is (5~7):(3~2):(2~1).

[0011] Preferably, the total mass of the first metering dispersant and the second metering dispersant accounts for 0.5% to 5% of the total mass of the solid mixed powder; wherein the first metering dispersant accounts for 0.3% to 2% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 0.2% to 3% of the total mass of the solid mixed powder.

[0012] Preferably, the preparation process of the photocurable premix is ​​as follows: under light-protected conditions, the photocurable prepolymer, photocurable monomer, additives and photoinitiator are mixed and ball-milled to obtain the photocurable premix.

[0013] Preferably, the mass ratio of the photocurable prepolymer to the photocurable monomer is (1-3):(1-2).

[0014] Preferably, the refractive index of the additive is 1.6; the additive accounts for 5% to 10% of the mass percentage of the photocurable prepolymer.

[0015] Preferably, the volume ratio of the photocurable premix to the aluminum nitride ceramic powder is not less than 40%.

[0016] Preferably, in step S2, the printing thickness of each layer during the layer-by-layer printing process is 25–40 μm.

[0017] Preferably, the degreasing temperature is 300–600℃ and the degreasing time is 2–4 h; the sintering temperature is 1750–1850℃ and the holding time during sintering is 2–6 h.

[0018] An aluminum nitride ceramic part is obtained by the above-described molding method, and the density of the aluminum nitride ceramic part is greater than 97%.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention discloses a method for forming aluminum nitride ceramic parts. First, aluminum nitride ceramic powder and sintering aid powder are mixed to obtain a solid mixed powder, which is then ball-milled. A first metering dispersant is added during ball milling. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, followed by the addition of a second metering dispersant, and ball milling continues to obtain a slurry. Then, based on a three-dimensional model of the part, the slurry is used for layer-by-layer printing, while simultaneously curing using an ultraviolet light beam to obtain an aluminum nitride ceramic green body. Finally, the aluminum nitride ceramic green body is degreased and sintered to obtain the aluminum nitride ceramic part. In this preparation method, aluminum nitride ceramic powder with three different particle size distributions is mixed with sintering aid powder and then sintered. The smaller particle size of the aluminum nitride ceramic powder makes the sintering process more favorable, while the larger particle size effectively increases the curing depth of the slurry, thus ensuring the dense sintering of the aluminum nitride ceramic while effectively increasing the curing depth. In addition, by adding a high-refractive-index additive to the photocurable premix, the refractive index difference between the additive and the powder is reduced, which further improves the curing depth of the slurry. Finally, a three-dimensional model is used for layer-by-layer printing to achieve near-net-shape forming of complex parts. This solves the shortcomings of existing aluminum nitride ceramic processing methods, such as poor performance and simple structure. At the same time, no subsequent processing is required, which shortens the processing time, saves costs, and eliminates the dependence on molds in traditional processing methods. This enables the mass production of aluminum nitride ceramic parts and the forming of complex parts.

[0021] Furthermore, the aluminum nitride ceramic powder is a gradation of aluminum nitride ceramic powder with particle sizes of 10μm, 2μm and 500nm; the mass ratio of the 10μm, 2μm and 500nm aluminum nitride ceramic powder is (5~7):(3~2):(2~1), which can effectively improve the density of ceramic green bodies and sintered parts.

[0022] Furthermore, the total mass of the first metering dispersant and the second metering dispersant accounts for 0.5% to 5% of the total mass of the solid mixed powder; wherein, the first metering dispersant accounts for 0.3% to 2% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 0.2% to 3% of the total mass of the solid mixed powder, which can effectively make the ceramic powder more uniformly mixed in the photosensitive additive.

[0023] Furthermore, the mass ratio of the photocurable prepolymer to the photocurable monomer is (1-3):(1-2); the refractive index of the additive is 1.6; the additive accounts for 5%-10% of the mass of the photocurable prepolymer, which can effectively reduce the refractive index difference between the ceramic powder and the additive and improve the curing depth.

[0024] Furthermore, the volume ratio of the photocurable premix to the aluminum nitride ceramic powder is not less than 40%, which can effectively obtain a ceramic green body with high density.

[0025] Furthermore, in step S2, during the layer-by-layer printing process, the printing thickness of each layer is 25-40 μm, which can achieve good layer-to-layer bonding.

[0026] Furthermore, the degreasing temperature is 300–600℃, and the degreasing time is 2–4 hours; the sintering temperature is 1750–1850℃, and the holding time during sintering is 2–6 hours, which can effectively produce high-density and high-strength aluminum nitride parts. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic flowchart of a molding method for an aluminum nitride ceramic part according to the present invention.

[0029] Figure 2 This is a schematic flowchart of a molding method for an aluminum nitride ceramic part according to Embodiment 5 of the present invention;

[0030] Figure 3 The values ​​represent the curing depths of the aluminum nitride ceramic curing sheets obtained in Examples 1-10 of this invention. Detailed Implementation

[0031] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0032] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0033] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0034] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0035] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0036] like Figure 1 As shown, the present invention provides a method for forming aluminum nitride ceramic parts, comprising the following steps:

[0037] S1: Aluminum nitride ceramic powder and sintering aid powder are mixed to obtain a solid mixed powder, which is then ball-milled. During ball milling, a first metering dispersant is added. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a continuous gradation of three sizes.

[0038] The aluminum nitride ceramic powder is a mixed powder of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm, and 500 nm; the mass ratio of the 10 μm, 2 μm, and 500 nm aluminum nitride ceramic powders is (5-7):(3-2):(2-1). The sintering aid is any one or more of Y₂O₃, CaO, Dy₂O₃, Li₂O, BaO, MgO, SrO₂, and La₂O₃, used to improve the density of aluminum nitride and reduce the sintering temperature, and its content is 0.5%-5% of the total mass of the aluminum nitride ceramic powder.

[0039] The total mass of the first and second metered dispersants accounts for 0.5% to 5% of the total mass of the solid mixed powder; wherein the first metered dispersant accounts for 0.3% to 2% of the total mass of the solid mixed powder, and the second metered dispersant accounts for 0.2% to 3% of the total mass of the solid mixed powder. The dispersant is any of the coupling agents, and the total mass of the dispersants added in both steps accounts for 0.5% to 5% of the total mass of the solid mixed powder. The dispersant added during ball milling accounts for 0.3% to 2% of the total mass of the solid mixed powder, and the dispersant added during slurry mixing accounts for 0.2% to 3% of the total mass of the solid mixed powder. Using coupling agents, i.e., dispersants, to modify aluminum nitride powder can promote the compatibility between the powder and the additives. For organic solvents, a small dosage should be selected while ensuring excellent slurry performance to prevent part deformation due to excessive shrinkage during subsequent degreasing and sintering. Adding the dispersant during ball milling promotes uniform dispersion and mixing of the powder. In this invention, the additive is resin.

[0040] The preparation process of the photocurable premix is ​​as follows: under light-protected conditions, the photocurable prepolymer, photocurable monomer, additives, and photoinitiator are mixed and ball-milled to obtain the photocurable premix. Specifically, under light-protected conditions, the photocurable prepolymer and photocurable monomer are added to a ball mill jar according to a mixing ratio of (1-3):(1-2). Simultaneously, a high-refractive-index additive with a refractive index of 1.6 is introduced, and the additive accounts for 5%-10% of the mass of the photocurable prepolymer. The photoinitiator is weighed and added to the ball mill jar, and finally mixed to obtain the photocurable premix. The curing depth of the premix reaches up to 90 μm, and the mass of the photoinitiator is 0.4%-2% of the mass of the photocurable monomer. This photocurable premix has a high curing crosslinking density, which helps improve alloy performance, and the curing speed is fast, reducing the time required to achieve complete curing and effectively increasing the curing depth.

[0041] The photocurable prepolymer is any one or a mixture of at least two of epoxy acrylate, polyurethane acrylate, and polyester propylene ether acrylate, which can effectively give the cured monolayer good strength and toughness; the photocurable monomer is any one or a mixture of at least two of 1,6-hexanediol diacrylate (HDDA), tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), diisopentanetetraol hexaacrylate (DPHA), and acrylamide morpholine (ACMO), which can effectively ensure that the cured monolayer is free from deformation; the photoinitiator is any one or a mixture of at least two of triphenylphosphine oxide (TPO), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), and benzoyl dimethyl ether (651), which has high initiation efficiency and good stability, and can effectively improve the curing depth.

[0042] Preferably, the volume ratio of the photocurable premix to the aluminum nitride ceramic powder is not less than 40%. During the test operation, the volume of the aluminum nitride ceramic powder is calculated based on the density and mass of the aluminum nitride ceramic powder.

[0043] In this step, ball milling is performed first. Specifically, aluminum nitride ceramic and sintering aid powder are selected, mixed to obtain a solid powder, and then placed in a ball mill for dissociation and ball milling. Next, a premix is ​​prepared. Specifically, under light-protected conditions, the photocurable prepolymer and monomer are added to a ball mill jar according to the mixing ratio, along with a high refractive index additive and a weighed photoinitiator. The mixture is then thoroughly mixed to obtain the photocurable premix. Finally, a slurry is prepared. Specifically, the ball-milled solid powder is sieved, dried, and added to the photocurable premix solvent. An appropriate amount of dispersant is gradually added to promote the dispersion of the solid powder. After thorough stirring, the mixture is ball-milled at high speed to obtain a slurry. Throughout this process, the introduction of the photocurable premix and subsequent mixing and storage should be carried out in a dark room to avoid light exposure, especially ultraviolet light, to ensure the slurry maintains good fluidity and prevents deterioration.

[0044] S2: Based on the three-dimensional model of the part, the slurry is used for layer-by-layer printing, while simultaneously curing with an ultraviolet light beam to obtain an aluminum nitride ceramic preform; during the layer-by-layer printing process, the printing thickness of each layer is 25-40 μm. Specifically, the prepared slurry is loaded into a photocuring device, and using an ultraviolet light beam, a surface exposure scanning method is employed to cure and print layer by layer according to the three-dimensional model of the part, obtaining a cured aluminum nitride ceramic preform.

[0045] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0046] The degreasing temperature is 300–600℃, and the degreasing time is 2–4 hours; the sintering temperature is 1750–1850℃, and the holding time during sintering is 2–6 hours. To reduce the impact of the heating process on the properties of the blank, a gradient heating mode can be selected. Before reaching the degreasing temperature, the heating rate is controlled at above 5℃ / min, and as the temperature approaches the degreasing temperature, the heating rate is reduced to below 2℃ / min. Specifically, before 300℃, the heating rate is greater than 5℃ / min, and when the temperature is above 300℃, the heating rate is less than 2℃ / min.

[0047] The post-processing involves placing the photocured aluminum nitride ceramic preform into a debinding furnace for debinding. The debinding temperature is determined based on the thermogravimetric (TG) curve, typically within the range of significant mass change, usually 300℃ to 600℃. To ensure complete debinding, the holding time is 2-4 hours to ensure complete removal of the organic binder, followed by pre-firing at a specific temperature to maintain the preform's strength. Sintering is then performed at 1750℃-1850℃ for 2-6 hours under a pressure of 1-2 MPa, ultimately achieving an aluminum nitride density of over 97%. To minimize the impact of the heating process on the preform's properties, a gradient heating mode can be used. The heating rate is controlled above 5℃ / min before reaching the debinding temperature, decreasing to below 2℃ / min as the temperature approaches the debinding temperature.

[0048] This invention employs powder gradation, ensuring the dense sintering of aluminum nitride ceramics while simultaneously increasing the curing depth to as high as 90 μm through the addition of large-particle-size powder. Furthermore, by optimizing the additive formulation and introducing high-refractive-index additives, the refractive index difference between the additives and the powder is reduced, thereby increasing the curing penetration depth of the slurry. This invention achieves near-net-shape forming of complex parts, overcoming the shortcomings of existing aluminum nitride ceramic processing methods, such as poor performance and limited structural design. It also eliminates the need for subsequent processing, shortening processing time and saving costs. Moreover, this invention eliminates the dependence on molds in traditional processing methods, enabling the batch production of aluminum nitride ceramic parts and the forming of complex components.

[0049] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0050] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0051] Example 1

[0052] A method for forming aluminum nitride ceramics specifically includes the following steps:

[0053] 1. Raw material preparation

[0054] Three particle sizes of aluminum nitride ceramic powder were selected: 50g of 10μm powder, 20g of 2μm powder, and 30g of 500nm powder. 5g of Y₂O₃ was added as a sintering aid, and 10g of KH560 was added as a dispersant. All of these were added to a ball mill jar for dissociation and dispersion. 10g each of epoxy acrylate and polyurethane acrylate, 5g of a high refractive index additive, and 6g each of ACMO and DPHA were added, and 0.37g of TPO was added under light-protected conditions to form a photocurable premix.

[0055] 2. Green body preparation

[0056] The slurry is added to the photopolymerization equipment at a wavelength of 405nm. The surface exposure method is used. The parameters are adjusted to control the photopolymerization layer thickness at 25μm and the single-layer curing depth at 80μm. According to the 3D printing model, the slurry is cured layer by layer to produce an aluminum nitride part blank.

[0057] 3. Post-processing

[0058] The part blank was placed in a sintering furnace at room temperature. The degreasing temperature was 890℃, and the temperature was increased to 200℃ at a rate of 5℃ / min, then to 300℃ at a rate of 1℃ / min, held for 2 hours, then increased to 600℃ at a rate of 0.5℃ / min, held for 2 hours, and then increased to 890℃ at a rate of 1℃ / min for degreasing, held for 1 hour. Sintering was then carried out at 1850℃, 0.8MPa, and a holding time of 4 hours to obtain a highly dense aluminum nitride part with a dimensional accuracy of 0.08mm. The sample number obtained in this embodiment is 1.

[0059] Example 2

[0060] A method for forming aluminum nitride ceramic parts includes the following steps:

[0061] S1: Aluminum nitride ceramic powder and Y2O3 powder are mixed to obtain a solid mixed powder, which is then ball-milled. A first metering dispersant is added during ball milling. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a continuous gradation of three sizes.

[0062] The aluminum nitride ceramic powder is a mixture of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm, and 500 nm; the mass ratio of the 10 μm, 2 μm, and 500 nm aluminum nitride ceramic powders is 5.5:2.5:1. The mass of Y₂O₃ powder accounts for 3.5% of the total mass of the aluminum nitride ceramic powder. The first metering dispersant accounts for 1.5% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 2% of the total mass of the solid mixed powder. The volume ratio of the photocurable premix to the aluminum nitride ceramic powder is 41%.

[0063] The preparation process of the above-mentioned photocurable premix is ​​as follows: Under light-protected conditions, the photocurable prepolymer and photocurable monomer are added to a ball mill jar according to a mixing ratio of 2:1. Simultaneously, an additive with a refractive index of 1.6 is introduced, accounting for 8% of the mass of the photocurable prepolymer. A photoinitiator is weighed and added to the ball mill jar, and the mixture is finally prepared to obtain the photocurable premix. The mass of the photoinitiator is 1.2% of the mass of the photocurable monomer.

[0064] The photocurable prepolymer is epoxy acrylate; the photocurable monomer is diisopentanetetraol hexaacrylate (DPHA); and the photoinitiator is triphenylphosphine oxide (TPO).

[0065] S2: Based on the three-dimensional model of the part, the slurry is used for layer-by-layer printing, and ultraviolet light is used for curing to obtain an aluminum nitride ceramic blank; during the layer-by-layer printing process, the printing thickness of each layer is 30μm.

[0066] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0067] The degreasing temperature was 350℃, and the degreasing time was 3.5 hours. The sintering temperature was 1840℃, and the holding time during sintering was 3 hours. To reduce the impact of the heating process on the performance of the blank, a gradient heating mode can be selected. Before reaching the degreasing temperature, the heating rate is controlled at above 5℃ / min, and when approaching the degreasing temperature, the heating rate is reduced to below 2℃ / min. Specifically, before 300℃, the heating rate is 5.5℃ / min, and when the temperature is above 300℃, the heating rate is 1.5℃ / min. The sample obtained in this embodiment is numbered 2.

[0068] Example 3

[0069] A method for forming aluminum nitride ceramic parts includes the following steps:

[0070] S1: Aluminum nitride ceramic powder and Y2O3 powder are mixed to obtain a solid mixed powder, which is then ball-milled. A first metering dispersant is added during ball milling. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a continuous gradation of three sizes.

[0071] The aluminum nitride ceramic powder is a mixture of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm, and 500 nm; the mass ratio of the 10 μm, 2 μm, and 500 nm aluminum nitride ceramic powders is 5:3:2. The mass of Y₂O₃ powder accounts for 0.5% of the total mass of the aluminum nitride ceramic powder. The first metering dispersant accounts for 0.3% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 0.2% of the total mass of the solid mixed powder. The volume ratio of the photocurable premix to the aluminum nitride ceramic powder is 40%.

[0072] The preparation process of the above-mentioned photocurable premix is ​​as follows: Under light-protected conditions, the photocurable prepolymer and photocurable monomer are added to a ball mill jar according to a mixing ratio of 1:1. Simultaneously, an additive with a refractive index of 1.6 is introduced, accounting for 5% of the mass percentage of the photocurable prepolymer. A photoinitiator is weighed and added to the ball mill jar, and the mixture is finally prepared to obtain the photocurable premix. The mass of the photoinitiator is 0.4% of the mass of the photocurable monomer. The photocurable prepolymer is epoxy acrylate; the photocurable monomer is 1,6-hexanediol diacrylate (HDDA); and the photoinitiator is triphenylphosphine oxide (TPO).

[0073] S2: Based on the three-dimensional model of the part, the slurry is used for layer-by-layer printing, and ultraviolet light is used for curing to obtain an aluminum nitride ceramic blank; during the layer-by-layer printing process, the printing thickness of each layer is 25μm.

[0074] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0075] The degreasing temperature was 300℃, and the degreasing time was 4 hours. The sintering temperature was 1750℃, and the holding time during sintering was 6 hours. To reduce the impact of the heating process on the performance of the blank, a gradient heating mode can be selected. Before reaching the degreasing temperature, the heating rate is controlled at above 5℃ / min, and when approaching the degreasing temperature, the heating rate is reduced to below 2℃ / min. Specifically, before 300℃, the heating rate is 6℃ / min, and when the temperature is above 300℃, the heating rate is 1℃ / min. The sample obtained in this embodiment is numbered 3.

[0076] Example 4

[0077] A method for forming aluminum nitride ceramic parts includes the following steps:

[0078] S1: Aluminum nitride ceramic powder and Y2O3 powder are mixed to obtain a solid mixed powder, which is then ball-milled. A first metering dispersant is added during ball milling. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a continuous gradation of three sizes.

[0079] The aluminum nitride ceramic powder is a mixture of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm, and 500 nm; the mass ratio of the 10 μm, 2 μm, and 500 nm aluminum nitride ceramic powders is 6:2.5:1. The mass of the Y₂O₃ powder accounts for 2% of the total mass of the aluminum nitride ceramic powder. The first metering dispersant accounts for 1% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 1% of the total mass of the solid mixed powder. The volume ratio of the photocurable premix to the aluminum nitride ceramic powder is 44%.

[0080] The preparation process of the above-mentioned photocurable premix is ​​as follows: Under light-protected conditions, the photocurable prepolymer and photocurable monomer are added to a ball mill jar according to a mixing ratio of 2:1.5. Simultaneously, an additive with a refractive index of 1.6 is introduced, accounting for 8% of the mass percentage of the photocurable prepolymer. A photoinitiator is weighed and added to the ball mill jar, and the mixture is finally prepared to obtain the photocurable premix. The mass of the photoinitiator is 1.5% of the mass of the photocurable monomer.

[0081] The photocurable prepolymer is polyurethane acrylate; the photocurable monomer is tripropylene glycol diacrylate (TPGDA); and the photoinitiator is phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (819).

[0082] S2: Based on the three-dimensional model of the part, the slurry is used for layer-by-layer printing, and ultraviolet light is used for curing to obtain an aluminum nitride ceramic blank; during the layer-by-layer printing process, the printing thickness of each layer is 30μm.

[0083] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0084] The degreasing temperature was 400℃, and the degreasing time was 3 hours; the sintering temperature was 1800℃, and the holding time during sintering was 4 hours. The sample number obtained in this embodiment is 4.

[0085] Example 5

[0086] like Figure 2 As shown, a method for forming an aluminum nitride ceramic part includes the following steps:

[0087] S1: Aluminum nitride ceramic powder and Y2O3 powder are mixed to obtain a solid mixed powder, which is then ball-milled. A first metering dispersant is added during ball milling. Under light-protected conditions, the ball-milled solid mixed powder is added to a photocurable premix, and a second metering dispersant is added. Ball milling continues to obtain a slurry. The aluminum nitride ceramic powder is a continuous gradation of three sizes.

[0088] The aluminum nitride ceramic powder is a mixture of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm, and 500 nm; the mass ratio of the 10 μm, 2 μm, and 500 nm aluminum nitride ceramic powders is 7:2:1. The mass of the Y₂O₃ powder accounts for 5% of the total mass of the aluminum nitride ceramic powder. The first metering dispersant accounts for 2% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 3% of the total mass of the solid mixed powder. The volume ratio of the photocurable premix to the aluminum nitride ceramic powder is 45%.

[0089] The preparation process of the above-mentioned photocurable premix is ​​as follows: Under light-protected conditions, the photocurable prepolymer and photocurable monomer are added to a ball mill jar according to a mixing ratio of 3:2. Simultaneously, an additive with a refractive index of 1.6 is introduced, accounting for 10% of the mass of the photocurable prepolymer. A photoinitiator is weighed and added to the ball mill jar, and the mixture is finally prepared to obtain the photocurable premix. The mass of the photoinitiator is 2% of the mass of the photocurable monomer.

[0090] The photocurable prepolymer is polyester propylene ether acrylate; the photocurable monomer is trimethylolpropane triacrylate (TMPTA); and the photoinitiator is benzoyl dimethyl ether (651).

[0091] S2: Based on the three-dimensional model of the part, the slurry is used for layer-by-layer printing, and ultraviolet light is used for curing to obtain an aluminum nitride ceramic blank; during the layer-by-layer printing process, the printing thickness of each layer is 40μm.

[0092] S3: Degreasing and sintering the aluminum nitride ceramic blank to produce the aluminum nitride ceramic part.

[0093] The degreasing temperature was 600℃, and the degreasing time was 2 hours; the sintering temperature was 1850℃, and the holding time during sintering was 2 hours. The sample number obtained in this embodiment is 5.

[0094] Example 6

[0095] The difference between this embodiment and Example 5 is that the photosensitive agent is a photocurable prepolymer of polyester propylene ether acrylate; the photocurable monomers are trimethylolpropane triacrylate (TMPTA) and acrylamide morpholine (ACMO) in a mass ratio of 1:1; and the photoinitiator is triphenylphosphine oxide (TPO). The sample number obtained in this embodiment is 6.

[0096] Example 7

[0097] The difference between this embodiment and Example 5 is that no prepolymer was added to the photosensitive additive system; only photocurable monomers were introduced. The photocurable monomers were trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), and diisopentane terephthalate hexaacrylate (DPHA). The sample number obtained in this embodiment is 7.

[0098] Example 8

[0099] The difference between this embodiment and Example 5 is that the prepolymer in the photosensitive additive system is epoxy acrylate, and the photocurable monomers are trimethylolpropane triacrylate (TMPTA) and tripropylene glycol diacrylate (TPGDA). The sample number obtained in this embodiment is 8.

[0100] Example 9

[0101] The difference between this embodiment and Example 5 is that no prepolymer was added to the photosensitive additive system; only photocurable monomers were introduced. The photocurable monomers were trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), and diisopentane terephthalate hexaacrylate (DPHA). The sample number obtained in this embodiment is 9.

[0102] Example 10

[0103] The difference between this embodiment and Example 5 is that the prepolymer in the photosensitive additive system is epoxy acrylate and polyester propylene ether acrylate, the photocurable monomers are trimethylolpropane triacrylate (TMPTA), acrylamide morpholine (ACMO) and diisopentane terephthalol hexaacrylate (DPHA), and the photoinitiator is triphenylphosphine oxide (TPO). The sample number obtained in this embodiment is 10.

[0104] Depend on Figure 3 It can be seen that the curing penetration depth of the aluminum nitride ceramic curing sheet prepared by the present invention is basically above 80μm, and can reach up to 90μm, which has good performance.

[0105] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method of forming an aluminum nitride ceramic part, characterized by, The method comprises the following steps: S1: mixing aluminum nitride ceramic powder and sintering aid powder to obtain a solid mixed powder, then performing ball milling treatment, adding a first metering dispersant during the ball milling, adding the ball-milled solid mixed powder into a photocuring premix under light shielding conditions, adding a second metering dispersant, and continuing the ball milling to prepare a slurry; the aluminum nitride ceramic powder is a gradation of three particle sizes; S2: using the slurry to perform layer-by-layer printing according to a three-dimensional model of a part, and using an ultraviolet light beam to perform curing to obtain an aluminum nitride ceramic green body; S3: performing debinding and sintering on the aluminum nitride ceramic green body to prepare the aluminum nitride ceramic part; The aluminum nitride ceramic powder is a gradation of aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm and 500 nm; the mass ratio of the aluminum nitride ceramic powders with particle sizes of 10 μm, 2 μm and 500 nm is (5-7):(3-2):(2-1); The total mass of the first metering dispersant and the second metering dispersant accounts for 0.5%-5% of the total mass of the solid mixed powder; the first metering dispersant accounts for 0.3%-2% of the total mass of the solid mixed powder, and the second metering dispersant accounts for 0.2%-3% of the total mass of the solid mixed powder; The preparation process of the photocuring premix is as follows: under light shielding conditions, a photocuring prepolymer, a photocuring monomer, a high-refractive-index aid and a photoinitiator are mixed and ball milled to prepare the photocuring premix; the mass ratio of the photocuring prepolymer and the photocuring monomer is (1-3):(1-2).

2. The method of claim 1 wherein the aluminum nitride ceramic part is formed by a process comprising: The high-refractive-index aid has a refractive index of 1.6; the mass percentage of the high-refractive-index aid in the photocuring prepolymer is 5%-10%. ​ 3. The method of claim 1 wherein the aluminum nitride ceramic part is formed by a process comprising: The volume ratio of the photocuring premix to the aluminum nitride ceramic powder is not less than 40%.

4. The method of claim 1 wherein the aluminum nitride ceramic part is formed by a process comprising: In the step S2, the printing thickness of each layer in the layer-by-layer printing is 25-40 μm.

5. The method of claim 1 wherein the aluminum nitride ceramic part is formed by a process comprising: The debinding temperature is 300-600 ℃, and the debinding time is 2-4 h; the sintering temperature is 1750-1850 ℃, and the holding time during the sintering process is 2-6 h.

6. An aluminum nitride ceramic part, characterized by, The aluminum nitride ceramic part prepared by the forming method has a density greater than 97%.

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