Method for the production of large-sized ceramic parts by 3D printing

Abstract

The application discloses a method for preparing large-size ceramic parts by 3D printing, which comprises the following steps: weighing ceramic powder, dispersant, isobutylene-maleic anhydride copolymer, acrylamide, N,N'-methylene bisacrylamide and water, mixing and ball milling to obtain ceramic slurry, adding N,N,N',N'-tetramethyl ethylenediamine and ammonium persulfate to the ceramic slurry and continuing ball milling, pouring the obtained slurry into a barrel after defoaming, sealing and baking to obtain printing feed, adopting direct writing 3D printing equipment to perform screw extrusion printing to obtain a wet blank, performing secondary gelation and drying on the wet blank to obtain a green body, sintering the green body to obtain a ceramic blank, and performing precision machining and polishing on the ceramic blank to obtain a large-size ceramic part. The method has the advantages of large printing working stroke, low printing feed binder content, high solid content, difficulty in cracking during drying and sintering, and the like, and can realize rapid and safe preparation of large-size ceramic parts.

Description

Technical Field

[0001] This invention relates to the field of ceramic parts manufacturing technology, and more specifically to a method for manufacturing large-size ceramic parts using 3D printing. Background Technology

[0002] With the rapid development of modern science and technology, cutting-edge manufacturing fields have placed new demands on materials. Ceramics not only possess excellent thermodynamic properties and stable physicochemical properties, but also exhibit unique properties in fields such as optics, electronics, and biology, and have been widely used in aerospace, new energy, biomedicine, and other areas. However, due to their hard and brittle nature, ceramics are difficult to process. Traditional manufacturing techniques struggle to produce ceramic products with complex and irregular structures, and are also costly and time-consuming, failing to meet the demands of modern industry for product diversification and rapid market response.

[0003] Ceramic 3D printing technology fundamentally changes traditional manufacturing processes such as turning, planing, milling, and grinding. Based on a three-dimensional digital information model, 3D printing technology uses a layer-by-layer processing method to first shape the raw material and then sinter it into a finished product. It has significant advantages in lightweight simulation design and integrated fabrication of complex ceramic components. Furthermore, this technology has the advantages of simple manufacturing process, short cycle time, and low cost, reducing the time and economic costs of product development.

[0004] However, in the 3D printing of large-size ceramic parts, laser energy-based technologies such as SLS and SLM often lead to cracks and residual stress due to drastic temperature changes during the printing process. Meanwhile, technologies such as FDM, DLP, and DIW often require the addition of large amounts of organic binders, which can also cause defects such as cracks during subsequent drying and binder removal processes. Furthermore, the resulting sintered parts have low density, significantly hindering the application of 3D printing technology in large-size ceramic components. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for preparing large-size ceramic parts by 3D printing, which has a large working stroke, low feed binder content, high solid content, is not easy to crack during drying and sintering, and can realize the rapid and safe preparation of large-size ceramic parts.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0007] A method for fabricating large-size ceramic parts using 3D printing includes the following steps:

[0008] (1) Weigh ceramic powder, dispersant, isobutylene-maleic anhydride copolymer, acrylamide, N,N'-methylenebisacrylamide and water, mix and ball mill to obtain ceramic slurry, wherein, by mass fraction, ceramic powder is 70% to 90%, dispersant is 0 to 1%, isobutylene-maleic anhydride copolymer is 0.1% to 0.4%, acrylamide is 0.5% to 2%, N,N'-methylenebisacrylamide is 0.05% to 0.2%, and water is 9% to 29%;

[0009] (2) Add N,N,N',N'-tetramethylethylenediamine and ammonium persulfate to the ceramic slurry, continue ball milling, defoam the obtained slurry, pour it into the barrel, seal the barrel and bake it to make the slurry gel solidify, and obtain the printing feed;

[0010] (3) Connect the above-mentioned barrel containing printing feed to the direct writing 3D printing equipment, import the printing model, and use screw extrusion printing to prepare a wet blank. At least one dimension of the model is ≥50cm.

[0011] (4) The obtained wet blank is gelled a second time, and the wet blank after the second gel is dried until the weight no longer changes to obtain a green blank. The green blank is sintered to obtain a ceramic blank. After precision processing and polishing, a large-size ceramic part is obtained.

[0012] In the above-mentioned method for preparing large-size ceramic parts using 3D printing, preferably, in step (1), the ball milling media is one of alumina balls, zirconia balls and silicon nitride balls, the mass ratio of material to ball is 1:2 to 3, and the ball milling time is 3h to 24h; in step (2), the ball milling time is 5min to 10min.

[0013] In the above-described method for preparing large-size ceramic parts using 3D printing, preferably, in step (1), the isobutylene-maleic anhydride copolymer includes one or more of Isobam-104, Isobam-104-WS, and Isobam-600-AF, the dispersant includes one of ammonium citrate, ammonium polyacrylate, and tetramethylammonium hydroxide, and the ceramic powder includes one or more of alumina powder, silicon nitride powder, magnesium oxide powder, and yttrium oxide powder.

[0014] In the above-described method for preparing large-size ceramic parts using 3D printing, preferably, in step (2), the mass of N,N,N',N'-tetramethylethylenediamine is 0.01% to 0.1% of the mass of the ceramic slurry, and the mass of ammonium persulfate is 0.01% to 0.1% of the mass of the ceramic slurry.

[0015] In the above-mentioned method for preparing large-size ceramic parts using 3D printing, preferably, in step (2), the baking temperature is 40℃~70℃ and the baking time is 0.5h~2h.

[0016] In the above-mentioned method for preparing large-size ceramic parts using 3D printing, preferably, in step (3), the screw extrusion printing speed is 10mm / s to 30mm / s.

[0017] In the above-mentioned method for preparing large-size ceramic parts using 3D printing, preferably, in step (4), the secondary gelation is carried out in a low-temperature and humid environment, the temperature of which is 20℃~40℃ and the humidity of which is 30%~80%, and the drying temperature regime is as follows: first drying at 20℃~40℃ for 12h~48h, then drying at 50℃~70℃ for 12h~48h, and then drying at 80℃~100℃ for 12h~48h.

[0018] In the above-mentioned method for preparing large-size ceramic parts using 3D printing, preferably, in step (4), the sintering temperature is 1400℃~2000℃, the sintering method is one of gas pressure sintering, atmospheric pressure sintering and hot pressure sintering, the atmosphere of gas pressure sintering is nitrogen or argon, the atmosphere of hot pressure sintering is nitrogen or argon, and the atmosphere of atmospheric pressure sintering is air.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] This invention provides a method for fabricating large-size ceramic parts using 3D printing. This method features a large working stroke, enabling rapid printing of large-size ceramic parts. In the prior art, neither acrylamide nor ISOBAM systems have been applied to DIW3D printing. The applicant has found that when using acrylamide alone to prepare large-size preforms, adding too much acrylamide results in high strength and viscosity after curing, making it unsuitable for DIW3D printing. Adding less acrylamide results in suitable viscosity for DIW3D printing, but the wet preform has low strength and is prone to cracking during drying. Using only the ISOBAM system, with its low organic additive content and easy drying, can be used to prepare large-size ceramic parts. However, ISOBAM has a slow gel time, and the gel network is broken after extrusion, leading to a decrease in viscosity and making rapid gelation difficult, thus unsuitable for DIW3D printing. Therefore, this invention uses the ISOBAM gel system and the acrylamide gel system in synergy. The acrylamide system is used to achieve rapid gelation, resulting in a printing feed with a suitable viscosity. It can also effectively prevent powder sedimentation during the ISOBAM gelation process, enabling DIW3D printing of large-size blanks. After printing, the ISOBAM secondary gelation provides strength to the wet blank, enabling the safe drying of large-size ceramic parts. After sintering, large-size ceramic parts are finally obtained. Detailed Implementation

[0021] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention. All materials and instruments used in the following embodiments are commercially available.

[0022] Example 1

[0023] A method for fabricating large-size ceramic parts using 3D printing according to the present invention includes the following steps:

[0024] (1) Weigh 5000g of alumina powder, 15g of ammonium citrate, 15g of Isobam-104, 60g of acrylamide, 6g of N,N'-methylenebisacrylamide, and 1120g of deionized water and place them in a ball mill jar for mixing and ball milling to obtain ceramic slurry. The ball milling medium is alumina balls, and the mass ratio of material to balls is 1:2. The ball milling time is 10h.

[0025] (2) Add 0.7g N,N,N',N'-tetramethylethylenediamine and 1.8g ammonium persulfate to the ceramic slurry, and continue ball milling for 5 minutes. Pour out the ball-milled slurry and place it in a vacuum defoamer for defoaming. After defoaming, pour it into a feed cylinder, seal the feed cylinder, and bake it in an oven at 60°C for 1 hour to allow the slurry to gel and solidify (acrylamide crosslinking) to obtain the printing feed.

[0026] (3) Connect the barrel containing the printing feed to the direct write 3D (DIW3D) printing equipment through the pipe, import the printing model, and use the screw extrusion printing method to prepare a wet blank. The printing speed is 15mm / s. The printing model is a cylindrical structure (i.e., a cylindrical structure for semiconductor equipment), with a diameter of 60cm, a height of 30cm, and a wall thickness of 2.2cm.

[0027] (4) The above-mentioned wet blanks were placed in a low-temperature and humid environment for secondary gelation (mainly the Isobam gelation process). The temperature of the low-temperature and humid environment was 25℃, the humidity was 40%, and the time was 48h. The wet blanks after secondary gelation were transferred to an oven for drying until the weight no longer changed, and green blanks were obtained. The baking regime was 30℃×24h+60℃×24h+90℃×12h. The dried green blanks were placed in a sintering furnace for sintering. The sintering method was atmospheric pressure sintering, the atmosphere was air, and the sintering temperature was 1600℃, and ceramic blanks were obtained. After precision machining and polishing of the ceramic blanks using CNC machine tools, large-size alumina ceramic parts were obtained.

[0028] Example 2

[0029] A method for fabricating large-size ceramic parts using 3D printing according to the present invention includes the following steps:

[0030] (1) Weigh 5000g of alumina powder, 15g of ammonium citrate, 10g of ISOBAM-104, 5g of Isobam-600-AF, 45g of acrylamide, 4.5g of N,N'-methylenebisacrylamide and 1050g of deionized water and place them in a ball mill jar for mixing and ball milling to obtain ceramic slurry. The ball milling media is alumina balls, the mass ratio of material to balls is 1:2, and the ball milling time is 10h.

[0031] (2) Add 0.7g N,N,N',N'-tetramethylethylenediamine and 1.8g ammonium persulfate to the ceramic slurry, and continue ball milling for 5 minutes. Pour out the ball-milled slurry and place it in a vacuum defoamer for defoaming. After defoaming, pour it into a feed cylinder, seal the feed cylinder, and bake it in an oven at 60°C for 1 hour to allow the slurry to gel and solidify (acrylamide crosslinking) to obtain the printing feed.

[0032] (3) Connect the barrel containing the printing feed to the direct writing 3D printing equipment through a pipe, import the printing model, and use screw extrusion to prepare a wet blank. The printing speed is 12mm / s. The printing model is the same as the model in Example 1.

[0033] (4) The wet blank was placed in a low-temperature and humid environment for secondary gelation. The temperature of the low-temperature and humid environment was 25℃, the humidity was 40%, and the time was 60h. The wet blank after secondary gelation was transferred to an oven for drying until the weight no longer changed, and a green blank was obtained. The baking regime was 30℃×24h+60℃×24h+90℃×12h. The dried green blank was placed in a sintering furnace for sintering. The sintering method was atmospheric pressure sintering, the atmosphere was air, and the temperature was 1600℃ to obtain a ceramic blank. The ceramic blank was precision machined and polished using a CNC machine tool to obtain large-size alumina ceramic parts.

[0034] Example 3

[0035] A method for fabricating large-size ceramic parts using 3D printing according to the present invention includes the following steps:

[0036] (1) Weigh 5000g of alumina powder, 25g of tetramethylammonium hydroxide, 10g of ISOBAM-104 (isobutylene-maleic anhydride copolymer), 5g of Isobam-600-AF, 50g of acrylamide, 5g of N,N'-methylenebisacrylamide, and 1080g of deionized water and place them in a ball mill jar for ball milling to obtain ceramic slurry. The ball milling media is alumina balls, the material:ball mass ratio is 1:3, and the ball milling time is 10h.

[0037] (2) Add 1g of N,N,N',N'-tetramethylethylenediamine and 2g of ammonium persulfate to the ceramic slurry, and continue ball milling for 5 minutes. Pour out the ball-milled slurry and place it in a vacuum defoamer for defoaming. After defoaming, pour it into a feed cylinder, seal the feed cylinder, and place it in an oven to bake at 60°C for 1 hour to allow the slurry to gel and solidify (acrylamide crosslinking) to obtain the printing feed.

[0038] (3) Connect the barrel containing the printing feed to the direct writing 3D printing equipment through a pipe, import the printing model, and use screw extrusion to prepare a wet blank. The printing speed is 15mm / s. The printing model is the same as the model in Example 1.

[0039] (4) The wet blank was placed in a low-temperature and humid environment for secondary gelation. The temperature of the low-temperature and humid environment was 25℃, the humidity was 40%, and the time was 40h. The wet blank after secondary gelation was transferred to an oven for drying until the weight no longer changed, and a green blank was obtained. The baking regime was 30℃×24h+60℃×24h+90℃×12h. The dried green blank was placed in a sintering furnace for sintering. The sintering method was atmospheric pressure sintering, the atmosphere was air atmosphere, and the sintering temperature was 1600℃, and a ceramic blank was obtained. After precision machining and polishing of the ceramic blank using a CNC machine tool, large-size alumina ceramic parts were obtained.

[0040] Example 4

[0041] A method for fabricating large-size ceramic parts using 3D printing according to the present invention includes the following steps:

[0042] (1) Weigh 5100g silicon nitride powder, 250g magnesium oxide powder, 250g yttrium oxide powder, 35g tetramethylammonium hydroxide, 10g Isobam-104, 5g Isobam-600-AF, 130g acrylamide, 13g N,N'-methylenebisacrylamide, and 2200g deionized water and place them in a ball mill jar for ball milling to obtain ceramic slurry. The ball milling medium is silicon nitride balls, the material:ball mass ratio is 1:3, and the ball milling time is 15h.

[0043] (2) Add 1g of N,N,N',N'-tetramethylethylenediamine and 3g of ammonium persulfate to the ceramic slurry, and continue ball milling for 5 minutes. Pour out the ball-milled slurry and place it in a vacuum defoamer for defoaming. After defoaming, pour it into a feed cylinder, seal the feed cylinder, and place it in an oven to bake at 60°C for 1 hour to allow the slurry to gel and solidify (acrylamide crosslinking) to obtain the printing feed.

[0044] (3) Connect the barrel containing the printing feed to the direct writing 3D printing equipment through a pipe, import the printing model, and use screw extrusion to prepare a wet blank. The printing speed is 15mm / s. The printing model is the same as the model in Example 1.

[0045] (4) The above-mentioned wet blank was placed in a low-temperature and humid environment for secondary gelation. The temperature of the low-temperature and humid environment was 25℃, the humidity was 40%, and the time was 60h. The wet blank after secondary gelation was transferred to an oven for drying until the weight no longer changed, and a green blank was obtained. The baking regime was 30℃×48h+60℃×24h+90℃×12h. The dried green blank was placed in a sintering furnace for sintering. The sintering method was gas pressure sintering, the atmosphere was nitrogen atmosphere, the sintering temperature was 1850℃, and the gas pressure was 2.5MPa, and a ceramic blank was obtained. The ceramic blank was precision machined and polished using a CNC machine tool to obtain large-size silicon nitride ceramic parts.

[0046] Comparative Example 1

[0047] A method for preparing large-sized ceramic parts is basically the same as in Example 1, except that 150g of hydroxyethyl cellulose is used instead of acrylamide and Isobam-104. As a result, the parts cracked during drying and could not be prepared.

[0048] Comparative Example 2

[0049] A method for preparing large-sized ceramic parts is basically the same as that in Example 1, except that 400g of hydroxyethyl cellulose is used instead of acrylamide and Isobam-104.

[0050] Comparative Example 3

[0051] A method for preparing large-sized ceramic parts is basically the same as that in Example 4, except that 500g of hydroxyethyl cellulose is used instead of acrylamide, Isobam-104 and Isobam-600-AF.

[0052] Comparative Example 4

[0053] A method for preparing large-size ceramic parts is basically the same as in Example 1, except that acrylamide is replaced with Isobam-104, which cannot be molded due to its lower viscosity.

[0054] Comparative Example 5

[0055] A method for preparing large-sized ceramic parts is basically the same as in Example 1, except that: if Isobam-104 is replaced with acrylamide, it will dry and crack.

[0056] Table 1. Performance test results of ceramic parts in Examples 1-4 and Comparative Examples 2-3.

[0057] Example 1 99.3 16.4 395 no Example 2 99.4 16.6 416 no Example 3 99.4 16.7 423 no Example 4 99 14.3 871 no Comparative Example 2 95.7 13.6 192 no Comparative Example 3 94.3 11.7 377 no

[0058] As shown in Table 1, the large-size alumina ceramics of Examples 1-3 have a density of at least 99.3%, a flexural strength of at least 395 MPa, and a Vickers hardness of at least 16.4 GPa. The large-size silicon nitride ceramic of Example 4 has a density of 99%, a hardness of 14.3 GPa, and a flexural strength of 871 MPa, and none of them exhibited drying cracking. Compared to Example 1, Comparative Example 1 has a higher binder content, but it cracked directly during the drying process, making subsequent sintering steps impossible. The large-size alumina ceramics provided in Examples 1-3 show a significant improvement in mechanical properties compared to the alumina ceramic provided in Comparative Example 2. This is mainly because Comparative Example 2 added more binder to prevent drying cracking, resulting in insufficient sintering density and poor mechanical properties. For the same reason, the large-size silicon nitride ceramic provided in Example 4 also shows a significant improvement in mechanical properties and density compared to the silicon nitride ceramic provided in Comparative Example 3. Therefore, the method for preparing large-size ceramic parts using 3D printing provided by this invention can produce ceramic parts with excellent mechanical properties and complex shapes. Compared with traditional DIW printing technology, the method provided by this invention effectively avoids the generation of drying defects, reduces the binder content, and improves the density and mechanical properties of ceramic parts. It can realize the safe preparation of large-size irregular ceramic parts. Moreover, compared with ceramic parts prepared by traditional methods, the method provided by this invention has a simple process, is suitable for industrial production, and can save a lot of processing costs.

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for fabricating large-size ceramic parts using 3D printing, characterized in that, Includes the following steps: (1) Weigh ceramic powder, dispersant, isobutylene-maleic anhydride copolymer, acrylamide, N,N'-methylenebisacrylamide and water and mix and ball mill to obtain ceramic slurry, wherein, by mass fraction, ceramic powder is 70% to 90%, dispersant is 0 to 1%, isobutylene-maleic anhydride copolymer is 0.1% to 0.4%, acrylamide is 0.5% to 2%, N,N'-methylenebisacrylamide is 0.05% to 0.2%, and water is 9% to 29%; (2) Add N,N,N',N'-tetramethylethylenediamine and ammonium persulfate to the ceramic slurry, continue ball milling, defoam the obtained slurry, pour it into the barrel, seal the barrel and bake it to make the slurry gel solidify, and obtain the printing feed; (3) Connect the above-mentioned barrel containing printing feed to the direct writing 3D printing equipment, import the printing model, and use screw extrusion printing to prepare a wet blank. At least one dimension of the model is ≥50cm. (4) The obtained wet blank is subjected to secondary gelation, the secondary gelation is the gelation process of Isobam, the wet blank after secondary gelation is dried until the weight no longer changes, and a green blank is obtained. The green blank is sintered to obtain a ceramic blank, and after precision processing and polishing, a large-size ceramic part is obtained.

2. The method for preparing large-size ceramic parts using 3D printing according to claim 1, characterized in that, In step (1), the ball milling media is one of alumina balls, zirconium oxide balls and silicon nitride balls, the mass ratio of material to ball is 1:2 to 3, and the ball milling time is 3h to 24h; in step (2), the ball milling time is 5min to 10min.

3. The method for preparing large-size ceramic parts using 3D printing according to claim 1, characterized in that, In step (1), the isobutylene-maleic anhydride copolymer includes one or more of Isobam-104, Isobam-104-WS and Isobam-600-AF, the dispersant includes one of ammonium citrate, ammonium polyacrylate and tetramethylammonium hydroxide, and the ceramic powder includes one or more of alumina powder, silicon nitride powder, magnesium oxide powder and yttrium oxide powder.

4. The method for fabricating large-size ceramic parts using 3D printing according to claim 1, characterized in that, In step (2), the mass of N,N,N',N'-tetramethylethylenediamine is 0.01% to 0.1% of the mass of the ceramic slurry, and the mass of ammonium persulfate is 0.01% to 0.1% of the mass of the ceramic slurry.

5. The method for preparing large-size ceramic parts using 3D printing according to any one of claims 1 to 4, characterized in that, In step (2), the baking temperature is 40℃~70℃ and the baking time is 0.5h~2h.

6. The method for preparing large-size ceramic parts using 3D printing according to any one of claims 1 to 4, characterized in that, In step (3), the screw extrusion printing speed is 10mm / s to 30mm / s.

7. The method for preparing large-size ceramic parts using 3D printing according to any one of claims 1 to 4, characterized in that, In step (4), the secondary gel is carried out in a low-temperature and humid environment. The temperature of the low-temperature and humid environment is 20℃~40℃, and the humidity is 30%~80%. The drying temperature regime is as follows: first, dry at 20℃~40℃ for 12h~48h, then dry at 50℃~70℃ for 12h~48h, and then dry at 80℃~100℃ for 12h~48h.

8. The method for fabricating large-size ceramic parts using 3D printing according to any one of claims 1 to 4, characterized in that, In step (4), the sintering temperature is 1400℃~2000℃, the sintering method is one of gas pressure sintering, atmospheric pressure sintering and hot pressure sintering, the atmosphere of gas pressure sintering is nitrogen or argon, the atmosphere of hot pressure sintering is nitrogen or argon, and the atmosphere of atmospheric pressure sintering is air.