Composite material for additive manufacturing, granulation and additive manufacturing method

Abstract

The application discloses a composite material for additive manufacturing, a granulation and additive manufacturing method, and relates to the technical field of additive manufacturing. The composite material for additive manufacturing comprises a first powder and a second powder. The first powder is at least one of a ceramic or a ceramic matrix composite material. The second powder is a Ti-7-10 wt.% Si alloy powder. The amount of the second powder is 10-30 vol.% of the first powder. Adding a certain amount of Ti-7-10 wt.% Si alloy powder to the ceramic or the ceramic matrix composite material can effectively reduce the sintering temperature and obtain sufficient liquid phase, so that a high-density printing-sintering part is obtained. In the sintering process, carburizing or nitriding sintering is adopted, so that the Ti-7-10 wt.% Si alloy can be converted into TiC, SiC or TiN and Si3N4, so as to further improve the density and mechanical properties of the sintering part.

Description

Technical Field

[0001] This application relates to the field of additive manufacturing technology, and in particular to composite materials for additive manufacturing, composite material granulation methods, and additive manufacturing methods. Background Technology

[0002] Binder jet printing, also known as 3DP printing or BJ printing, works by using a powder bed to spray organic or inorganic binder onto the powder surface through a printhead. Layers of this binder are stacked to create a pre-designed 3D model, which is then cured, debonded, and sintered to become the final printed product. 3DP technology offers advantages such as low cost, high efficiency, no need for support structures, and the ability to print large-sized parts, making it one of the hottest technologies in additive manufacturing.

[0003] A drawback of 3DP printing technology is its high requirement for powder shape and particle size. Only powders with good sphericity and a particle size of 15-200 micrometers can be effectively spread to complete the printing process. Currently, 3DP printing technology can successfully prepare high-density metal and alloy samples. However, for 3DP-printed ceramics and ceramic matrix composites, even at sintering temperatures as high as 1600-1900℃, there is still a lack of sufficient liquid phase to complete the densification process, resulting in lower density and poorer mechanical properties after sintering. Summary of the Invention

[0004] In view of this, the first aspect of this application provides a composite material for additive manufacturing, in which a certain content of Ti-7-10wt.%Si alloy powder is added to ceramics or ceramic matrix composites, which can effectively reduce the sintering temperature and obtain sufficient liquid phase to obtain high-density printed-sintered parts; the specific technical solution adopted is as follows:

[0005] The additive manufacturing composite material includes a first powder and a second powder, wherein the first powder is at least one of ceramic or ceramic matrix composite materials, and the second powder is a Ti-7-10wt.%Si alloy powder, and the amount of the second powder is 10-30 vol.% of the first powder.

[0006] The first powder includes at least one of oxide ceramics, carbide ceramics, boride ceramics, and nitride ceramics.

[0007] The particle size of the first powder is 0.01-3 micrometers, or / and the particle size of the second powder is 0.5-5 micrometers.

[0008] Adding Ti-7-10wt.%Si alloy powder to the first powder has the following advantages:

[0009] (1) The ratio of Ti to Si in the Ti-7-10wt.% Si alloy is reasonable, and its melting point is much lower than that of Ti, which can reduce the sintering temperature of traditional ceramics (1600-1900℃) to 1350-1500℃;

[0010] (2) The ratio of Ti to Si in the Ti-7-10wt.%Si alloy is reasonable, which ensures sufficient liquid phase even at a lower sintering temperature, thereby improving the density after sintering.

[0011] The second aspect of this application provides a granulation method for additive manufacturing composite materials. The additive manufacturing composite material provided in this application is mixed with an adhesive and then granulated to obtain granulated powder that is spherical or near-spherical with a particle size of 10-350 micrometers.

[0012] The granulation methods include spray granulation, fluidized bed granulation, and compression-crushing granulation.

[0013] The adhesive includes inorganic or organic binders; the organic binder includes at least one of paraffin, PEG, PVA, or rubber.

[0014] The granulation method provided in this application also includes pre-calcining the granulated powder to obtain pre-calcined powder after granulation; the pre-calcination process includes degreasing at 300-500℃ and pre-sintering at 600-1000℃.

[0015] The degreasing atmosphere is hydrogen, argon, nitrogen, or vacuum; the pre-sintering atmosphere is vacuum or argon.

[0016] By granulation, the additive manufacturing composite material provided in this application is prepared into a particle size range suitable for 3DP printing, which is beneficial for powder spreading.

[0017] Pre-firing the granulated powder can give it a certain strength, which facilitates subsequent printing and makes the printed blank have higher strength.

[0018] A third aspect of this application provides an additive manufacturing method in which granulated powder or pre-calcined granulated powder obtained by the granulation method described in this application is subjected to binder jet printing, curing, degreasing, and sintering to obtain a printed-sintered part.

[0019] Preferably, the sintering process is carried out in one or a combination of atmospheres including vacuum, argon, methane, acetylene, nitrogen, and decomposed ammonia.

[0020] Using a vacuum degree of 10 -2 -10 -3 Vacuum sintering at pressure of Pa; or sintering at atmospheric pressure or in an argon atmosphere with a pressure of 1-10 MPa.

[0021] Preferably, sintering is performed in a methane atmosphere at atmospheric pressure; or in an acetylene atmosphere at atmospheric pressure; or in a decomposed ammonia atmosphere at atmospheric pressure; or in a nitrogen atmosphere at atmospheric pressure or a pressure of 1-10 MPa.

[0022] By using carburizing or nitriding sintering during the sintering process, Ti-7-10wt.%Si alloy can be transformed into TiC, SiC, or TiN, Si3N4, thereby successfully preparing high-density, high-performance ceramic matrix composite materials.

[0023] Preferably, the printing process includes: a blanking strength of 50%–90%, a powder spreading roller speed of 300–600 rpm; a powder layer thickness of 20 μm–300 μm, an adhesive saturation of 30%–120%, a powder spreading coarse roller speed of 200–300 rpm, a powder bed temperature of room temperature–280°C; a curing temperature of 100°C–300°C, and a heat curing time of 0.5 h–12 h.

[0024] Or / and, the degreasing process after printing includes: a heating rate of 0.5℃ / min to 10℃ / min, a degreasing temperature of 300 to 1000℃, a holding time of 15 min to 300 min, and the degreasing process can be carried out in a hydrogen, inert gas atmosphere or in a vacuum.

[0025] Or / and, the sintering process after printing, curing, and degreasing includes: a heating rate of 5-50℃ / min, a sintering temperature of 1350-1500℃, and a holding time of 5-1200min.

[0026] The beneficial effects of this application are:

[0027] (1) Adding a certain amount of Ti-7-10wt.%Si alloy powder to ceramics and ceramic matrix composites can significantly reduce the sintering temperature from 1600-1900℃ to 1350-1500℃; and at a lower sintering temperature, sufficient liquid phase can be guaranteed, which can improve the density of the sintered printed-sintered parts, thereby significantly improving the mechanical properties of the sintered printed-sintered parts.

[0028] (2) After granulation, the additive manufacturing composite material provided in this application is prepared into a particle size range suitable for 3DP printing, which is beneficial for powder spreading.

[0029] (3) By using carburizing or nitriding sintering during the sintering process, Ti-7-10wt.%Si alloy can be transformed into TiC, SiC or TiN, Si3N4, thus successfully preparing high-density, high-performance ceramic matrix composite materials.

[0030] (4) The density of the ceramic material 3DP printed-sintered parts prepared by the additive manufacturing method described in this application is as high as 90-99%, while the density of conventional ceramic material 3DP printed-sintered parts is only 40-60%.

[0031] (5) Ti-7-10wt.%Si alloy powder significantly improves the density of ceramic powder printed-sintered parts better than pure Ti powder. Detailed Implementation

[0032] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0033] The "printed blank" mentioned in this application refers to the printed blank obtained after adhesive spraying printing and curing of the target sample.

[0034] This application provides an additive manufacturing method for ceramics and ceramic matrix composites, specifically including:

[0035] A) Prepare a mixed powder by adding 0.5-5 μm Ti-7-10 wt.% Si alloy powder to ceramic powder, and then prepare granulated powders of ceramics and ceramic matrix composites using conventional granulation methods:

[0036] In this application, the ceramic powder mentioned in step A) includes, but is not limited to, various oxide ceramics, nitride ceramics, boride ceramics, and carbide ceramics, with a particle size of 0.01-3 μm; the Ti-7-10wt.%Si alloy powder has a particle size of 0.5-5 μm, and the content of Ti-7-10wt.%Si alloy powder in the mixed powder is 10-30 vol.%; the granulated powder has a spherical, near-spherical, or irregular shape, preferably spherical, and the particle size of the ceramic and ceramic matrix composite granulated powder is 10-350 μm, preferably 15-60 μm; the conventional granulation method includes, but is not limited to, spray granulation, fluidized bed granulation, and compression-crushing granulation, and can be prepared by commercially available methods or methods well known to those skilled in the art. After the above-mentioned granulated powder is prepared, the granulated powder can be pre-calcined. The pre-calcination process includes degreasing at 300-500℃ and pre-sintering at 600-1000℃. The degreasing atmosphere is hydrogen, argon, nitrogen and vacuum, and the pre-sintering atmosphere is vacuum and argon.

[0037] B) The granulated powder or the pre-calcined granulated powder prepared in step (A) is subjected to binder spray printing and curing.

[0038] In this application, the adhesive jet printing process in step B) includes: a drop strength of 50% to 90%, a powder spreading roller speed of 300 to 600 rpm; a powder layer thickness of 20 μm to 300 μm, an adhesive saturation of 30% to 120%, a powder spreading coarse roller speed of 200 to 300 rpm, a powder bed temperature of room temperature to 280°C; a curing temperature of 100°C to 300°C, and a heat curing time of 0.5 h to 12 h.

[0039] C) Degreasing the printed blank;

[0040] In this application, the degreasing of the printed blank in step C) includes: a heating rate of 0.5℃ / min to 10℃ / min, a degreasing temperature of 300 to 1000℃, and a holding time of 15 min to 300 min. The degreasing process can be carried out in a hydrogen, inert gas atmosphere or in a vacuum.

[0041] D) Sintering of degreased parts;

[0042] In this application, the degreasing sintering process described in step D) includes: a heating rate of 0.1℃ / min to 50℃ / min, a sintering temperature lower than the melting point of the main printing material, and a holding time of 5min to 1200min. Depending on the characteristics of the printing material, the sintering process can be carried out in one or a combination of vacuum, argon, methane, acetylene, nitrogen, and decomposed ammonia atmospheres. Specifically, a vacuum of 10... -2 -10 -3 Vacuum sintering at Pa; or sintering at atmospheric pressure or argon atmosphere with a pressure of 1-10 MPa; or sintering at atmospheric pressure at methane atmosphere; or sintering at atmospheric pressure at acetylene atmosphere; or sintering at atmospheric pressure at decomposed ammonia atmosphere; or sintering at atmospheric pressure or nitrogen atmosphere with a pressure of 1-10 MPa.

[0043] E) Performance characterization of binder jet printing-sintered parts;

[0044] In this application, the performance characterization of the printed-sintered part in step E) involves testing the density, porosity, and hardness of the sintered part. The specific testing methods are as follows:

[0045] Density method: Density was measured using the Archimedes displacement method.

[0046] Bending strength test method: The test shall be conducted in accordance with the national standard GB / T 228.1-2010.

[0047] Fracture toughness test method: The test shall be conducted in accordance with GB / T 4161-1984 standard.

[0048] To further illustrate this application, the following detailed description is provided in conjunction with embodiments and comparative examples.

[0049] Example 1

[0050] 1. Mix 20 vol.% Ti-8.5 wt.% Si alloy powder (1 μm) with 80 vol.% SiC powder (0.2 μm) and then atomize and granulate the mixture. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is mainly PVA.

[0051] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0052] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 180℃, the curing time is 4 hours, and the curing atmosphere is air.

[0053] 4. Degreasing and sintering treatments will be performed. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere used for degreasing. The sintering process involves first heating at 10... -3 The furnace was then kept at 1450°C for 2 hours under vacuum and at 1450°C for 3 hours under atmospheric pressure methane atmosphere, and then cooled to room temperature in the furnace.

[0054] 5. The density and mechanical properties of the sintered printed blank are tested.

[0055] Comparative Example 1

[0056] 1. Select SiC powder with an original particle size of 0.2 μm and prepare SiC granulated powder by spray granulation. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is mainly PVA.

[0057] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0058] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 180℃, the curing time is 4 hours, and the curing atmosphere is air.

[0059] 4. The printed blank undergoes degreasing and sintering treatment. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon as the degreasing atmosphere. The sintering temperature is 1850℃ for 3 hours, followed by furnace cooling to room temperature, with a sintering atmosphere of 10. -3 A vacuum of Pa;

[0060] 5. The density and mechanical properties of the sintered printed blank are tested.

[0061] Example 2

[0062] 1. Mix 20 vol.% Ti-8.5 wt.% Si alloy powder (1 μm) with 80 vol.% Al2O3 powder (0.2 μm) and then atomize and granulate the mixture. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0063] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0064] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0065] 4. Perform degreasing and sintering treatments. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere used for degreasing. The sintering process involves first heating at 10... -3 It was held at 1400℃ under vacuum for 2 hours, then held at 1400℃ under nitrogen atmosphere (6MPa) for 1 hour, and then cooled to room temperature in the furnace.

[0066] 5. The density and mechanical properties of the sintered printed blank are tested.

[0067] Comparative Example 2

[0068] 1. Select Al2O3 powder with an original particle size of 0.2μm and prepare Al2O3 granulated powder by spray granulation. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0069] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0070] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0071] 4. The printed blank is degreased and sintered. The degreasing process is to hold at 400℃ for 1 hour and at 600℃ for 1 hour, with argon atmosphere. The sintering temperature is 1600℃, held for 3 hours, and then cooled to room temperature in the furnace with air atmosphere.

[0072] 5. The density and mechanical properties of the sintered printed blank are tested.

[0073] Example 3

[0074] 1. Mix 20 vol.% Ti-8.5 wt.% Si alloy powder (1 μm) with 80 vol.% Si3N4 powder (0.1 μm) and then atomize and granulate the mixture. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0075] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0076] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0077] 4. Perform degreasing and sintering treatments. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere used for degreasing. The sintering process involves first heating at 10... -2 It was kept at 1400℃ under vacuum for 2 hours, then kept at 1400℃ under nitrogen atmosphere (10MPa) for 1 hour, and then cooled to room temperature in the furnace.

[0078] 5. The density and mechanical properties of the sintered printed blank are tested.

[0079] Comparative Example 3

[0080] 1. Mix 20 vol.% Ti powder (1 μm) with 80 vol.% Si3N4 powder (0.1 μm) and then atomize and granulate the mixture. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0081] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0082] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0083] 4. Perform degreasing and sintering treatments. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere used for degreasing. The sintering process involves first heating at 10... -3The furnace was kept in a vacuum of 10 MPa and 1780°C for 2 hours, then kept in a nitrogen atmosphere (10 MPa) and 1780°C for 1 hour, and then cooled to room temperature with the furnace.

[0084] 5. The density and mechanical properties of the sintered printed blank are tested.

[0085] Comparative Example 4

[0086] 1. Select Si3N4 powder with an original particle size of 0.1μm and prepare Si3N4 granulated powder by spray granulation. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0087] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0088] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 180℃, the curing time is 4 hours, and the curing atmosphere is air.

[0089] 4. Degreasing and sintering treatments are performed. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere. The sintering process involves sintering at 1750℃ for 3 hours, followed by furnace cooling to room temperature, with 10 ppm argon atmosphere. -3 A vacuum of Pa;

[0090] 5. The density, microstructure, bending strength and hardness of the sintered printed blank are tested.

[0091] Example 4

[0092] 1. Mix 20 vol.% Ti-8.5 wt.% Si alloy powder (1 μm) with 80 vol.% TiB2 powder (0.3 μm) and then atomize and granulate the mixture. The particle size of the granulated powder is 15-60 micrometers. The organic binder in the granulated powder is PVA.

[0093] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0094] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0095] 4. Perform degreasing and sintering treatments. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere used for degreasing. The sintering process involves first heating at 10... -3 The furnace was kept in a vacuum of 8 MPa and 1450°C for 2 hours, then kept in a nitrogen atmosphere (8 MPa) and 1450°C for 1 hour, and then cooled to room temperature with the furnace.

[0096] 5. The density, microstructure, bending strength and hardness of the sintered printed blank are tested.

[0097] Comparative Example 5

[0098] 1. TiB2 powder with an original particle size of 0.3 μm was selected and TiB2 granulated powder was prepared by spray granulation. The particle size of the granulated powder was 15-60 micrometers. The organic binder in the granulated powder was PVA.

[0099] 2. The granulated powder is subjected to binder jet printing. The printing process is as follows: the printing layer thickness is 80 micrometers, the binder saturation is 65%, the powder bed temperature is 45℃, the powder bed drying time is 15s, the speed of the coarse powder spreading roller is 250rpm, and the speed of the fine powder spreading roller is 500rpm.

[0100] 3. The printed blank is subjected to powder removal and curing treatment. The curing temperature is 200℃, the curing time is 8 hours, and the curing atmosphere is air.

[0101] 4. Degreasing and sintering treatments are performed. The degreasing process involves holding at 400℃ for 1 hour and then at 600℃ for 1 hour, with argon atmosphere. The sintering process involves holding at 2000℃ for 3 hours, with 10 ppm argon atmosphere. -3 vacuum Pa

[0102] 5. The sintered printed preform was tested for density, microstructure, flexural strength, and hardness.

[0103] The relevant performance of Examples 1-4 and Comparative Examples 1-5 of this application is compared, as shown in Table 1.

[0104] Table 1. Experimental data and comparative data of Examples 1-4 and Comparative Examples 1-5 of this application.

[0105]

[0106]

[0107] Table 1 shows that the binder jet printing-debinding-sintering process using the mixed powder obtained by adding 20 vol.% Ti and 8.5 wt.% Si to the original SiC, Al2O3, Si3N4, and TiB2 powders respectively through atomization granulation, under atmospheric methane atmosphere and high-pressure nitrogen atmospheres of 6, 10, and 8 MPa, yielded densities of 98.5%, 97.3%, 96.5%, and 94.7%, respectively. In contrast, the SiC, Al2O3, Si3N4, and TiB2 powders prepared by conventional atomization granulation method, after undergoing conventional binder jet printing-debinding-sintering under vacuum conditions, showed poor printing and sintering results. The densities of the sintered parts were 56.2%, 53.1%, 49%, and 51%, respectively. However, the density of the sintered parts produced by mixing and atomizing Si3N4 powder with 20 wt.% pure Ti powder and then performing binder jet printing-debinding-sintering process was only 82.3%. The density and mechanical properties of the sintered parts were significantly lower than those of the Si3N4 powder with added Ti-8.5 wt.% Si, and the sintering temperature was significantly higher than that of the ceramic powder with added Ti-8.5 wt.% Si. This indicates that the Ti-8.5 wt.% Si alloy powder significantly improves the density of ceramic powder sintered parts than pure Ti powder. Table 1 shows that the experimental results proposed in this application, which uses atomized granulated ceramic mixed powder with added Ti-8.5wt.%Si for binder jet printing-debinding-sintering process, achieves a final density and mechanical properties that are significantly higher than those achieved by using conventional atomized granulated ceramic coarse-grained powder through conventional binder jet printing-debinding-sintering process.

Claims

1. A composite material for additive manufacturing, comprising a first powder and a second powder, wherein the first powder is at least one powder selected from ceramics or ceramic matrix composites, and the second powder is a Ti-7-10wt.%Si alloy powder, wherein the amount of the second powder is 10-30 vol.% of the first powder.

2. The composite material for additive manufacturing according to claim 1, characterized in that: The first powder includes at least one of oxide ceramics, carbide ceramics, boride ceramics, and nitride ceramics.

3. The composite material for additive manufacturing according to claim 1, characterized in that: The particle size of the first powder is 0.01-3 micrometers, or / and the particle size of the second powder is 0.5-5 micrometers.

4. A granulation method for composite materials used in additive manufacturing, characterized in that: The additive manufacturing composite material according to any one of claims 1 to 3 is mixed with an adhesive and then granulated to obtain granulated powder.

5. The granulation method for additive manufacturing composite materials according to claim 4, characterized in that: The granulated powder is pre-calcined to obtain pre-calcined granulated powder; the pre-calcination process includes degreasing at 300-500℃ and pre-sintering at 600-1000℃.

6. The granulation method for additive manufacturing composite materials according to claim 5, characterized in that: The degreasing atmosphere in the pre-firing process is hydrogen, argon, nitrogen or vacuum; the pre-sintering atmosphere is vacuum or argon.

7. An additive manufacturing method, characterized in that: The granulated powder obtained by the granulation method according to any one of claims 4 to 6 is subjected to binder spray printing, curing, degreasing, and sintering to obtain a printed-sintered part.

8. The additive manufacturing method according to claim 7, characterized in that: The sintering process is carried out in one or more of the following atmospheres: vacuum, argon, methane, acetylene, nitrogen, and decomposed ammonia.

9. The additive manufacturing method according to claim 8, characterized in that: Sintering is carried out in a methane atmosphere at atmospheric pressure; or in an acetylene atmosphere at atmospheric pressure; or in a decomposed ammonia atmosphere at atmospheric pressure; or in a nitrogen atmosphere at atmospheric pressure or with a pressure of 1-10 MPa.

10. The additive manufacturing method according to claim 7, characterized in that: The printing process includes: a blanking strength of 50%–90%, a powder spreading roller speed of 300–600 rpm; a powder layer thickness of 20 μm–300 μm; a binder saturation of 30%–120%; a powder spreading coarse roller speed of 200–300 rpm; a powder bed temperature of room temperature–280℃; a curing temperature of 100℃–300℃; and a heat curing time of 0.5 h–12 h. Or / and, the degreasing process after printing includes: a heating rate of 0.5℃ / min to 10℃ / min, a degreasing temperature of 300 to 1000℃, a holding time of 15 min to 300 min, and the degreasing process can be carried out in a hydrogen, inert gas atmosphere or in a vacuum. Or / and, the sintering process after printing, curing, and degreasing includes: a heating rate of 5-50℃ / min, a sintering temperature of 1350-1500℃, and a holding time of 5-1200min.

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