A granulation method for preparing a binder jet printing powder based on a cold isostatic pressing process

Abstract

The application discloses a granulation method for preparing binder jetting printing powder based on a cold isostatic pressing process and relates to the technical field of additive manufacturing. The granulation method comprises the following steps: S1, ceramic powder 20-60 parts and additives 0.2-6 parts are treated by ball milling, uniformly mixed, dried, and sieved through an 80-120 mesh sieve to obtain mixed powder; S2, the mixed powder is subjected to cold isostatic pressing treatment to obtain ceramic block material; and S3, the ceramic block material is crushed, and powder with a preset particle size range is obtained, namely, binder jetting printing powder. Through the pure physical granulation path of cold isostatic pressing, the granulation particles with flowability close to that of coarse powder are formed, and the uniformity of powder laying is ensured; the compatibility conflict between the granulation powder and subsequent printing glue can be completely eliminated, the double goals of "no binder interference" and "retention of fine powder sintering activity" of the binder jetting printing powder are achieved, the types of powder that can be used by the binder jetting printing technology are effectively expanded, and the wide application of the technology is promoted.

Description

Technical Field

[0001] This invention relates to the field of binder jet printing additive manufacturing technology, and in particular to a granulation method for preparing binder jet printing powder based on cold isostatic pressing process. Background Technology

[0002] Additive manufacturing (AM), commonly known as 3D printing, revolutionizes traditional manufacturing methods through the principle of discrete stacking. Binder jetting technology, in particular, is widely used in precision casting, medical, and electronics fields due to its advantages such as good compatibility with various powders, a wide range of print sizes, and the elimination of the need for printing support structures. However, binder jetting technology requires powders with good flowability to ensure successful powder spreading. Therefore, coarse powders with a particle size greater than 20μm are often chosen for binder jetting printing. However, coarse powders have a small specific surface area, poor sintering activity, and are difficult to sinter densely. Although granulation processes can agglomerate fine powders into flowable granules that balance flowability and sintering activity, the binder introduced in traditional granulation processes can easily cause compatibility conflicts with subsequent printing adhesives, severely restricting the direct application of granulated powders in binder jetting systems. Developing novel granulation methods to eliminate two-stage binder interference has become a key requirement for overcoming this technological bottleneck. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a powder for adhesive jet printing, overcoming the compatibility problem between the binder in the granulated powder and the printing adhesive.

[0004] To address the above problems, the present invention proposes the following technical solution:

[0005] In a first aspect, the present invention provides a granulation method for preparing binder jet printing powder based on cold isostatic pressing, comprising the following steps:

[0006] S1. By mass, 20-60 parts of ceramic powder and 0-6.0 parts of additives are ball-milled, mixed, dried, and passed through an 80-120 mesh sieve to obtain a mixed powder.

[0007] S2. The mixed powder is subjected to cold isostatic pressing to obtain ceramic blocks;

[0008] S3. Crush the ceramic block and take powder with a preset particle size range to obtain the binder jet printing powder.

[0009] A further technical solution is that, in step S2, the pressure of the cold isostatic pressing is 20~500MPa, and the holding time is 2~20min.

[0010] A further technical solution is that, in step S2, the pressure of the cold isostatic pressing is 100~400MPa, and the holding time is 3~10min.

[0011] A further technical solution is that, in step S2, the pressure of the cold isostatic pressing treatment is 200~300MPa, and the holding time is 4~6min.

[0012] Understandably, the pressure and holding time of cold isostatic pressing can be flexibly adjusted according to different ceramic systems to balance particle density and redispersibility, ensuring that the granulated powder has sufficient mechanical strength to resist breakage during the powder spreading process, and can also accurately control the target particle size distribution through subsequent crushing and screening.

[0013] A further technical solution is that, in step S2, the mixed powder obtained in step S1 is placed in a vacuum bag for vacuum treatment, and then subjected to cold isostatic pressing.

[0014] A further technical solution is that the preset particle size range in step S3 is 50~400 mesh, for example 50 mesh, 80 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, and 400 mesh.

[0015] A further technical solution is that the particle size of the ceramic powder is 0.02~20μm, for example 0.02μm, 0.05μm, 0.10μm, 0.18μm, 0.25μm, 0.50μm, 0.80μm, 1.50μm, 3.5μm, 5.0μm, 10.0μm, 13.50μm, 15.50μm, 18.0μm, 20.0μm.

[0016] A further technical solution is that the ceramic powder is selected from at least one of oxide ceramic powder, nitride ceramic powder, carbide ceramic powder, and high-entropy ceramic powder.

[0017] A further technical solution is that the additive is selected from graphene, Re x E y At least one of the following, wherein Re is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and E is O, F or H.

[0018] A further technical solution is that the amount of the additive is 0 to 6.0 parts, for example, 0 parts, 0.2 parts, 0.5 parts, 2.0 parts, 4.0 parts, 5.5 parts, or 6.0 parts.

[0019] A further technical solution is that, in step S1, the ball milling speed is 100~800 r / min and the time is 1~15 h.

[0020] A further technical solution is as follows: the specific operation of step S1 is as follows: by mass, take the following components: 40-80 parts of dispersion medium, 20-60 parts of ceramic powder, 40-80 parts of grinding balls, and 0-6.0 parts of additives; add the above components to a ball mill jar for ball milling to obtain a ceramic slurry, then dry the ceramic slurry and sieve it to obtain a mixed powder. The dispersion medium is selected from at least one of water and alcohol.

[0021] In a second aspect, the present invention also provides a binder jet printing powder, which is prepared by the granulation method for preparing binder jet printing powder based on the cold isostatic pressing process described in the first aspect.

[0022] Thirdly, the present invention also provides a method for preparing a ceramic body using binder jet printing, which is prepared using the binder jet printing powder described in the second aspect, or using the powder obtained by the granulation method for preparing binder jet printing powder based on the cold isostatic pressing process described in the first aspect.

[0023] Compared with the prior art, the technical effects achieved by the present invention include:

[0024] The granulation method for preparing binder jet printing powder based on cold isostatic pressing provided by this invention achieves the dual goals of "no binder interference" and "retention of fine powder sintering activity" through the purely physical granulation path of cold isostatic pressing. This provides a new way to prepare powder with high fluidity, high sintering activity and wide compatibility for binder jet printing.

[0025] This invention physically compacts fine powder using cold isostatic pressing to form granulated particles with a flowability close to that of coarse powder, ensuring uniform powder distribution. By eliminating the use of binders or other molten substances found in traditional granulation processes, it completely eliminates compatibility conflicts between the granulated powder and subsequent printing adhesives, allowing the granulated powder to be directly compatible with binder spraying systems. This fully preserves the high sintering activity of the fine powder, resulting in sintered parts with significantly better density and mechanical properties than those produced with traditional coarse powder.

[0026] The granulation method of the present invention avoids the interference of binder residue on powder properties and has a simple process flow. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1This is a scanning electron microscope (SEM) image of the alumina granulated powder prepared in Example 1.

[0029] Figure 2 This is a particle size distribution diagram of the alumina granulated powder prepared in Example 1. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0032] It should also be understood that the terminology used in this specification of embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. As used in this specification of embodiments of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0033] Taking additive-free ceramic powder as an example, the granulation method for preparing binder jet printing powder based on cold isostatic pressing process provided by the present invention will be described.

[0034] Example 1

[0035] Measurements showed that 500g of Al₂O₃ ceramic powder with a particle size of 200nm, without granulation treatment, had a loose packing density of 0.813g / cm³. 3 .

[0036] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0037] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 200MPa and holding time of 5min, to obtain ceramic blocks.

[0038] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0039] Figure 1 This is a scanning electron microscope (SEM) image of the alumina granulated powder prepared in this embodiment.

[0040] Figure 2 This is a particle size distribution diagram of the alumina granulated powder obtained in this embodiment.

[0041] The loose packing density of the alumina granulated powder prepared in this embodiment is 1.025 g / cm³. 3 The median diameter is 2.65 μm, which is 26.07% higher than that of the alumina powder before granulation.

[0042] The alumina granulated powder prepared in this embodiment was subjected to binder jet printing and sintered at 1600 °C for 120 min. The density of the sintered sample was 50.28% and the flexural strength was 2.78 MPa.

[0043] Example 2

[0044] Measurements showed that 500g of Si3N4 ceramic powder with a particle size of 700nm had a loose packing density of 0.6927g / cm³. 3 .

[0045] S1. Take 500g of Si3N4 ceramic powder with a particle size of 700nm, 500g of anhydrous ethanol, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0046] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 200MPa and holding time of 5min, to obtain ceramic blocks.

[0047] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0048] The bulk density of the silicon nitride granulated powder prepared in this embodiment is 0.858 g / cm³. 3 The median diameter is 12.51 μm, which is 23.86% higher than that of silicon nitride powder before granulation. The powder's flowability is also greatly improved, enabling successful binder jet printing.

[0049] The silicon nitride granulated powder prepared in this embodiment was subjected to binder jet printing and gas pressure sintering at 1800 °C and 2 MPa nitrogen pressure for 4 h. The density of the sintered sample was 52.37% and the flexural strength was 8.86 MPa.

[0050] Comparative Example 1

[0051] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0052] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 100MPa and holding time of 5min, to obtain ceramic blocks.

[0053] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0054] The bulk density of the alumina granulated powder obtained in this case was 0.995 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 22.39%.

[0055] The alumina granulated powder obtained in this case was used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 48.39% and the flexural strength was 2.28 MPa.

[0056] Comparative Example 2

[0057] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0058] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 300MPa and holding time of 5min, to obtain ceramic blocks.

[0059] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0060] The bulk density of the alumina granulated powder obtained in this case was 1.043 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 28.29%.

[0061] The alumina granulated powder obtained in this case was used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 51.87% and the flexural strength was 3.08 MPa.

[0062] Comparative Example 3

[0063] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0064] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 400MPa and holding time of 5min, to obtain ceramic blocks.

[0065] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0066] The bulk density of the alumina granulated powder obtained in this case was 1.047 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 28.78%.

[0067] The alumina granules prepared in this case were used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 51.93% and the flexural strength was 3.10 MPa.

[0068] Comparative Example 4

[0069] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0070] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 200MPa and holding time of 2min, to obtain ceramic blocks.

[0071] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0072] The bulk density of the alumina granulated powder obtained in this case was 1.002 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 23.25%.

[0073] The alumina granules prepared in this case were used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 49.39% and the flexural strength was 2.52 MPa.

[0074] Comparative Example 5

[0075] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0076] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 200MPa and holding time of 8min, to obtain ceramic blocks.

[0077] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0078] The bulk density of the alumina granulated powder obtained in this case was 1.028 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 26.45%.

[0079] The alumina granulated powder obtained in this case was used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 50.32% and the flexural strength was 2.83 MPa.

[0080] Comparative Example 6

[0081] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0082] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters of the cold isostatic pressing are: pressure of 200MPa and holding time of 11min, to obtain ceramic blocks.

[0083] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0084] The bulk density of the alumina granulated powder obtained in this case was 1.029 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 26.57%.

[0085] The alumina granules prepared in this case were used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 50.37% and the flexural strength was 2.84 MPa.

[0086] Comparative Example 7

[0087] S1. Take 500g of Al2O3 ceramic powder with a particle size of 200nm, 500g of deionized water, and 500g of grinding balls and add them to a ball mill jar. Ball mill at 300rpm for 3h to obtain ceramic slurry. Then dry the ceramic slurry and pass it through a 100-mesh sieve to obtain mixed powder.

[0088] S2. The mixed powder is placed in a vacuum bag for vacuum treatment, and then placed in a cold isostatic press for cold isostatic pressing. The parameters for cold isostatic pressing are: pressure of 400MPa and holding time of 11min, to obtain ceramic blocks.

[0089] S3. Crush the ceramic block and then sieve it to select powder in the range of 100-200 mesh as the binder for jet printing, thus obtaining granulated powder.

[0090] The bulk density of the alumina granulated powder obtained in this case was 1.050 g / cm³. 3 Compared with the alumina powder before granulation, it increased by 29.15%.

[0091] The alumina granules prepared in this case were used for binder jet printing and sintered at 1600 ℃ for 120 min. The density of the sintered sample was 51.96% and the flexural strength was 3.12 MPa.

[0092] The granulation parameters and the properties of the granulated powder and ceramics obtained in Example 1 and Comparative Examples 1-7 are summarized in Table 1 below.

[0093] Table 1. Granulation parameters and properties of granulated powders obtained in Example 1 and Comparative Examples 1-7.

[0094]

[0095] As shown in Table 1, the granulated powder prepared by cold isostatic pressing (CIP) exhibited significantly higher bulk density than the original powder. Different CIP process parameters resulted in variations in the properties of the granulated powder. Under a constant holding time of 5 min, the effect of CIP pressure on the bulk density of the powder showed a significant nonlinear characteristic: when the pressure gradually increased from 100 MPa to 300 MPa, the bulk density of the powder increased from 0.995 g / cm³ to 1.043 g / cm³, an increase of 4.82%; however, when the pressure continued to increase to 400 MPa, the density only increased slightly from 1.043 g / cm³ to 1.050 g / cm³, a sharp drop to 0.67%. This indicates that above 300 MPa, the ceramic blocks were sufficiently compacted, and the marginal benefit of further pressurization significantly decreased.

[0096] Under a fixed pressure of 200 MPa, the effect of holding time on the loose density of powder exhibits a critical threshold effect. When the holding time is extended from 2 minutes to 8 minutes, the powder density steadily increases from 1.002 g / cm³ to 1.028 g / cm³; however, after the holding time exceeds 8 minutes (to 11 minutes), the density only increases slightly to 1.029 g / cm³, an increase of less than 0.097%, confirming that the powder compaction process is basically completed at the 8-minute mark.

[0097] Understandably, the pressure and holding time of cold isostatic pressing can be flexibly adjusted according to different ceramic systems to balance particle density and redispersibility, ensuring that the granulated powder has sufficient mechanical strength to resist breakage during the powder spreading process, and can also accurately control the target particle size distribution through subsequent crushing and screening.

[0098] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0099] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A granulation method for preparing binder jet printing powder based on cold isostatic pressing, characterized in that, Includes the following steps: S1. By mass, 20-60 parts of ceramic powder and 0-6.0 parts of additives are ball-milled, mixed, dried, and passed through an 80-120 mesh sieve to obtain a mixed powder. S2. The mixed powder is subjected to cold isostatic pressing to obtain ceramic blocks; S3. Crush the ceramic block and take the powder within the preset particle size range to obtain the binder jet printing powder; The additives are selected from graphene, Re x E y At least one of the following, wherein Re is Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb or Lu, and E is O, F or H; the binder jet printing powder does not contain binder or other molten substances; the content of the additive is not 0; In step S2, the pressure of the cold isostatic pressing is 200~500MPa, and the holding time is 5~20min.

2. The granulation method for preparing binder jet printing powder based on cold isostatic pressing as described in claim 1, characterized in that, Step S2 further includes placing the mixed powder obtained in step S1 into a vacuum bag for vacuum treatment, and then performing cold isostatic pressing.

3. The granulation method for preparing binder jet printing powder based on cold isostatic pressing as described in claim 1, characterized in that, The preset particle size range in step S3 is 50~400 mesh.

4. The granulation method for preparing binder jet printing powder based on cold isostatic pressing as described in claim 1, characterized in that, The particle size of the ceramic powder is 0.02~20μm.

5. The granulation method for preparing binder jet printing powder based on cold isostatic pressing as described in claim 1, characterized in that, The ceramic powder is selected from at least one of oxide ceramic powder, nitride ceramic powder, carbide ceramic powder, and high-entropy ceramic powder.

6. The granulation method for preparing binder jet printing powder based on cold isostatic pressing as described in claim 1, characterized in that, In step S1, the ball milling speed is 100~800 r / min and the time is 1~15 h.

7. A powder for adhesive jet printing, characterized in that, It is prepared by the granulation method for preparing binder jet printing powder based on cold isostatic pressing process as described in any one of claims 1-6.

8. A method for preparing ceramic bodies using binder jet printing, characterized in that, The powder can be prepared using the binder jet printing powder as described in claim 7, or using the powder obtained by the granulation method for preparing binder jet printing powder based on the cold isostatic pressing process as described in any one of claims 1-6.

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