Indirect additive manufacturing method for high-specific-gravity tungsten alloy part

Abstract

The invention discloses an indirect additive manufacturing method for a high-specific-gravity tungsten alloy part. According to the method, a high-molecular binder formula suitable for FDM printing of the tungsten alloy wire is provided, the problem that when the high-specific-gravity wire is extruded, due to heat generated by friction, the binder is volatilized is effectively solved, and the extruded wire is combined with degreasing sintering to form a tungsten alloy sample through the FDM printing technology; the binder is decomposed in a controllable and ordered manner according to the decomposition sequence of different binders in the degreasing process. The relative density of the sample prepared by the method can reach 99% (>), the tensile strength is 1157 MPa, the ductility is 17.8%, and the microhardness is 387 HV10; and various performance indexes are comparable with those of a powder metallurgy process.

Description

Technical Field

[0001] This invention relates to the field of high-density alloy technology, and specifically to an indirect additive manufacturing method for high-density tungsten alloy parts. Background Technology

[0002] High-density alloys (such as W-Ni-Fe, W-Ni-Cu, W-Ni-Co, W-Ni-Fe-Co, W-Ni-Fe-Cu, etc.), also known as high-density tungsten alloys, are metal-based composite materials with tungsten (85~98 wt.%) as the main component and one or more transition metal elements as the binder phase. High-density tungsten alloys have high density (… With advantages such as high strength, high rigidity, low coefficient of expansion, and high thermal conductivity, as well as good machinability, it is widely used in kinetic energy penetrator cores, pre-fragmented components, aircraft counterweights, electronic product counterweights, and radiation shielding components for nuclear energy and nuclear medical facilities.

[0003] High-density tungsten alloys are typically prepared using powder metallurgy, which involves processes such as powder mixing, pressing, sintering, and heat treatment. However, for parts with complex geometries, especially small-batch, multi-variety, or even customized products, powder metallurgy suffers from problems such as difficulty in forming complex geometric shapes, low material utilization, high mold and tooling costs, and long delivery cycles. Additive manufacturing technology, commonly known as 3D printing, offers a new approach to addressing these pain points. Among common additive manufacturing technologies, selective laser melting (SLM) and electron beam melting (EBM) can achieve high-precision forming, but they suffer from defects such as high equipment costs, strict powder requirements, high residual stress, cast-like grain structure, and residual porosity, resulting in poor material mechanical properties, especially high brittleness. Binder jetting technology also has strict requirements for the original powder and its application is limited by high shrinkage and insufficient density. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of poor sample performance, high equipment cost, and difficult post-processing in the existing technology of 3D printing high-density alloys, and to provide an indirect additive manufacturing method for high-density tungsten alloy parts.

[0005] The technical solution adopted in this invention is as follows:

[0006] An indirect additive manufacturing method for high-density tungsten alloy parts includes the following steps:

[0007] S1. 85~98 wt.% W powder, 0~10 wt.% Ni powder, 0~5 wt.% Fe powder or Cu powder and 0~5 wt.% Co powder are uniformly mechanically mixed to obtain a mixed powder;

[0008] S2. The mixed powder is kneaded with a polymer binder to obtain a feedstock, which is then extruded into filaments using an extruder.

[0009] The polymeric binder accounts for 40-60 vol.% of the feed; the polymeric binder consists of binder 1 and binder 2; binder 1 accounts for 75-90 vol.% of the total polymeric binder, and binder 2 accounts for 10-25 vol.% of the total polymeric binder; binder 1 is polyoxymethylene (POM), and binder 2 is one or more of stearic acid, paraffin wax, dioctyl phthalate (DOP), ethylene-vinyl acetate copolymer (EVA), and polypropylene (PP).

[0010] S3. The filament is FDM 3D printed to obtain a printing blank, which is then catalytically degreased, thermally degreased, sintered, and finally heat-treated to obtain an indirect additive manufacturing process for high-density tungsten alloy parts.

[0011] Preferably, the average particle size of the W powder is 1~30μm, the average particle size of the Ni powder is 1~25μm, the average particle size of the Fe powder is 1~30μm, the average particle size of the Co powder is 1~30μm, and the average particle size of the Cu powder is 1~50μm.

[0012] Preferably, the mechanical mixing uses a ball mill, with a ball-to-material weight ratio of 0.5 to 3; the spindle speed during ball milling is 2 to 300 rpm; and the milling time is 1 to 48 hours.

[0013] Preferably, the mixing is an internal mixing process, with a mixing temperature of 140~185 ℃, a screw speed of 3~50 rpm, and a mixing time of 30~120 min.

[0014] Preferably, during the extrusion process, the screw speed is 20~50 rpm; the extrusion temperature is 150~195 ℃; the extrusion pressure is 3~15 MPa; and the extruded filament specifications are 1.75±0.05mm or 2.85±0.075mm.

[0015] Preferably, during the FDM 3D printing process, the nozzle diameter is 0.25~0.8 mm; the platform temperature is 120~200 ℃; the printing temperature is 170~225 ℃; the printing speed is 30~90 mm / s; the printing layer thickness is 0.1~0.4 mm; the printing line width is 0.3~0.8 mm; the printing gear clamping distance is 1.0~2.0 mm; the printing infill density is 60~150%; and the printing infill method is one or more of the following: straight line, zigzag line, concentric circle, triangle, square, and polygon.

[0016] Preferably, the catalyst for catalytic degreasing is oxalic acid, nitric acid, formic acid, zeolite catalyst HZSM-5, or zirconium sulfate SO4.2- One of the ZrO2 types;

[0017] During the catalytic degreasing process, the furnace temperature is 100~150 ℃ and the holding time is 30~360 min; the vaporization box temperature is 140~180 ℃; the furnace atmosphere is nitrogen or argon with a flow rate of 30~150 L / min; and the acid inlet rate is 0.5~10 g / min.

[0018] Further preferably, during the thermal stripping process, the heating rate in the 30~600 ℃ stage is 1~10 ℃ / min, and the holding time is 60~720 min; the heating rate in the 600~1100 ℃ stage is 1~10 ℃, and the holding time is 60~480 min; the furnace atmosphere is nitrogen or argon, and the flow rate is 2~30 m³ / min. 3 / h.

[0019] Further preferably, during the sintering process, the heating rate from 0 to 600 °C is 5 °C / min, and the holding time is 30 to 720 min; the heating rate from 600 to 1200 °C is 2 to 5 °C, and the holding time is 30 to 180 min; the heating rate from 1200 to 1500 °C is 0.5 to 5 °C / min, and the holding time is 30 to 240 min; the furnace atmosphere is hydrogen, and the hydrogen flow rate is 5 to 20 m³ / min. 3 / h.

[0020] Further preferably, the heat treatment is oil quenching, with an oil quenching temperature of 800~1500 ℃ and a holding time of 30~120 min; during the oil quenching process, the cooling rate is 30~120 ℃ / s.

[0021] This invention employs fused deposition modeling (FDM), which, compared to SLM / EBM, cleverly avoids the significant technical and cost barriers of directly melting and forming high-melting-point, highly reactive metals. Compared to BJ forming, FDM avoids problems such as low strength of printed green blanks and high costs of equipment and raw materials. It enables rapid prototyping and production of complex-shaped, high-density tungsten alloy parts in a low-cost, low-barrier, and highly feasible manner.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) This invention provides a polymer binder formulation suitable for FDM printing of tungsten alloy filaments. The formulation solves the problem of binder volatilization caused by frictional heat generation during the extrusion of high-density filaments. Polypropylene (PP) in the binder component acts as a "process stabilizer" and "volatilization inhibitor" due to its higher thermal stability. Its mechanism of action is the diffusion path effect, which inhibits the volatilization of binder components due to high temperature during the extrusion filamentation process. EVA plays a role in enhancing toughness. Its mechanism is that the vinyl acetate (VA) unit in the molecular chain breaks down the polyethylene chain segment. The regularity of the material significantly reduces its crystallinity, resulting in soft, highly elastic amorphous regions. When the filament is subjected to external force, these soft amorphous regions can absorb and disperse impact energy through the extension, rotation, and deformation of the entangled network of molecular chains. DOP acts as a lubricant and diluent. Through its small molecule characteristics, it inserts into the polymer macromolecular chains, increasing the distance between the macromolecular chains. This greatly reduces the internal friction of chain segment movement, thus acting as a lubricant, reducing the viscosity of the feed, improving fluidity, and reducing pressure during filament extrusion, making it easier to control the filament diameter. (2) In this invention, the extruded filament is combined with FDM printing and debinding sintering to form a tungsten alloy sample. During the debinding process, the binder is decomposed in a controllable and orderly manner according to the different decomposition sequences of the binders. First, in the catalytic debinding stage, POM is removed first under the catalysis of nitric acid or oxalic acid vapor; second, in the thermal debinding stage, as the temperature increases, DOP, EVA, and PP are gradually removed in sequence according to different decomposition temperatures. After debinding, the sample is sintered with hydrogen to achieve a density of up to [insert density here]. Tensile strength 1107 MPa, elongation 17.8%, microhardness 440 HV10; compressive strength ≥2000 MPa, impact energy ≥ Its performance indicators are comparable to those of powder metallurgy.

[0024] (2) The method of the present invention is simple, easy to operate and low in cost. It can realize the rapid prototyping and production of complex-shaped high-density tungsten alloy parts, and is suitable for large-scale industrial production applications. Attached Figure Description

[0025] Figure 1 The microstructure of the filament in Example 7;

[0026] Figure 2 The rheological curve of the feed at 190°C in Example 7 is shown. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0028] The detection method in this invention is as follows:

[0029] The density of the alloy was tested according to GB / T 3850—2015 Determination of density of dense sintered metallic materials and cemented carbides.

[0030] The tensile strength test method is based on the standard GB / T 228.2-2015 Metallic materials, tensile testing—Part 2: High temperature test method; the elongation rate is the proportion of the sample spacing elongated after tensile fracture.

[0031] The hardness testing method refers to GB / T 4340.1-2024 Metallic materials - Vickers hardness test - Part 1: Test method;

[0032] The compressive strength test method refers to the standard GB / T 7314-2005 Metallic Materials - Compression Test at Room Temperature.

[0033] The impact toughness test method refers to "GB / T 1817-2017 Hard alloy room temperature impact toughness test method".

[0034] Example 1

[0035] 1. Powder Mixing: Tungsten, nickel, iron, and cobalt powders were added to a ball mill jar and uniformly mixed using a ball mill to obtain high-density powders. The average particle size of W powder was 13 μm, Ni powder was 16 μm, Fe powder was 30 μm, and Co powder was 30 μm. The ball-to-powder ratio was 1, the rotation speed was 100 RPM, and the ball milling time was 24 h. The proportions of each component were W: 93 wt.%; Ni: 4.9 wt.%; Fe: 1.4 wt.%; and Co: 0.7 wt.%.

[0036] 2. Feed Preparation: The prepared mixed powder and polyoxymethylene (POM) were added to a Banbury mixer and mixed to obtain the feed. The mixing temperature was 164℃, the screw speed was [missing value], and the mixing time was 2 hours. The polymer binder accounted for 45 vol.% of the total feed volume. Among the polymer binder, POM accounted for 88 vol.% of the total binder volume, polypropylene (PP) accounted for 5.25 vol.% of the total binder volume, ethylene-vinyl acetate copolymer (EVA) accounted for 5.25 vol.% of the total binder volume, and dioctyl phthalate (DOP) accounted for 1.5 vol.% of the total binder volume.

[0037] 3. Filament preparation: The feed is extruded into filaments with a specification of 1.75 mm through a twin-screw extruder, wherein the extrusion temperature is 170 ℃, the screw speed is 27 RPM, and the extrusion pressure is 7 MPa.

[0038] 4. FDM 3D Printing: After extruding the filament, a print blank is obtained. The nozzle diameter is 0.6 mm, the platform temperature is 140℃, the printing temperature is 180℃, the printing speed is 60 mm / s, the print layer thickness is 0.15 mm, the print line width is 0.4 mm, the gear clamping distance is 1.65 mm, the printing infill method is concentric circles, and the infill density is 100%.

[0039] 5. Degreasing: The printed blank undergoes catalytic degreasing. During degreasing, the furnace temperature is 110 ℃, the holding time is 240 min, the atmosphere is nitrogen, the flow rate is 70 L / min, the vaporization box temperature is 150-160 ℃, and the acid feed rate is 2.5 g / min. Subsequently, high-temperature thermal degreasing is performed in an atmosphere furnace. During thermal degreasing, the furnace atmosphere is nitrogen, and the flow rate is 6 m³ / min. 3 The heating rate is 5℃ / min for the 0~600℃ stage and the holding time is 480 min; the heating rate is 2℃ / min for the 600~1100℃ stage and the holding time is 480 min.

[0040] 6. Sintering: The thermally degassed sample is sintered in a hydrogen atmosphere. During the sintering process, the furnace atmosphere is hydrogen with a flow rate of 10 m³ / s. 3 / h, the heating rate for 0~600 ℃ is 5 ℃ / min, and the holding time is 300 min; the heating rate for 600~1200 ℃ is 3 ℃, and the holding time is 150 min; the heating rate for 1200~1500 ℃ is 1 ℃ / min, and the holding time is 180 min.

[0041] 7. Heat treatment: The sintered sample was heated to 1100℃ and held for 120 min, followed by oil quenching at a cooling rate of 80℃ / s, and finally the sample was obtained.

[0042] The relative density of the sample prepared by this method was tested to be 98.2%. The tensile strength is 1011 MPa, the elongation is 16.7%, the microhardness is 374 HV10, the compressive strength is 1703 MPa, and the impact energy is ≥ (As shown in Table 1).

[0043] Example 2

[0044] The preparation method of this embodiment is the same as that of Example 1, except that: in the feeding preparation process of this embodiment, the polymer binder accounts for 45 vol.% of the total feed volume, of which polyoxymethylene (POM) accounts for 95 vol.% of the total binder, polypropylene (PP) accounts for 1.5 vol.% of the total binder, ethylene-vinyl acetate copolymer (EVA) accounts for 1.5 vol.% of the total binder, and dioctyl phthalate (DOP) accounts for 2 vol.% of the total binder.

[0045] The relative density of the sample prepared in this embodiment was tested to be 96.22% ( The tensile strength is 674 MPa, the elongation is 9%, the microhardness is 334 HV10, the compressive strength is 1463 MPa, and the impact energy is ≥ (As shown in Table 1).

[0046] Example 3

[0047] The preparation method in this embodiment is the same as that in Example 1, except that: in the feeding preparation process of this embodiment, the polymer binder accounts for 45 vol.% of the total feed volume, of which polyoxymethylene (POM) accounts for 80 vol.% of the total binder, polypropylene (PP) accounts for 9.5 vol.% of the total binder, ethylene-vinyl acetate copolymer (EVA) accounts for 9.5 vol.% of the total binder, and dioctyl phthalate (DOP) accounts for 1.0 vol.% of the total binder.

[0048] The relative density of the sample prepared in this embodiment was tested to be 96.54% ( The tensile strength is 759 MPa, the elongation is 11.3%, the microhardness is 340 HV10, the compressive strength is 1504 MPa, and the impact energy is ≥ (As shown in Table 1).

[0049] Example 4

[0050] The preparation method in this embodiment is the same as that in Example 1, except that the printing line width in this embodiment is 0.6 mm.

[0051] The relative density of the sample prepared in this embodiment was tested to be 98.22% ( The tensile strength is 966 MPa, the elongation is 14.7%, the microhardness is 361 HV10, the compressive strength is 1655 MPa, and the impact energy is ≥ (As shown in Table 1).

[0052] Example 5

[0053] The preparation method in this embodiment is the same as that in Example 1, except that the printing layer thickness in this embodiment is 0.2 mm.

[0054] The relative density of the sample was tested to be 98.04%. The tensile strength is 951 MPa, the elongation is 14.2%, the microhardness is 354 HV10, the compressive strength is 1627 MPa, and the impact energy is ≥ (As shown in Table 1).

[0055] Example 6

[0056] The preparation method in this embodiment is the same as that in embodiment 1, except that the printing layer thickness is 0.2 mm and the printing line width is 0.6 mm.

[0057] The relative density of the sample was tested to be 97.91%. The tensile strength is 861 MPa, the elongation is 13.1%, the microhardness is 346 HV10, the compressive strength is 1581 MPa, and the impact energy is ≥ (As shown in Table 1).

[0058] Example 7

[0059] The preparation method in this embodiment is the same as that in Example 1, except that the printing temperature in this embodiment is 190 ℃.

[0060] The relative density of the sample was tested to be 99% ( The tensile strength is 1157 MPa, the elongation is 17.8%, the microhardness is 387 HV10, the compressive strength is 1768 MPa, and the impact energy is ≥ (As shown in Table 1).

[0061] Example 8

[0062] The preparation method in this embodiment is the same as that in Example 1, except that the printing temperature in this embodiment is 190 ℃ and the printing line width is 0.6 mm.

[0063] The relative density of the sample was tested to be 99% ( The tensile strength is 987 MPa, the elongation is 16.0%, the microhardness is 366 HV10, the compressive strength is 1684 MPa, and the impact energy is ≥ (As shown in Table 1).

[0064] Comparative Example 1

[0065] Adhesive jetting 3D printing

[0066] Mixing: Tungsten, nickel, iron, and cobalt powders were added to a ball mill jar and uniformly mixed using a ball mill to obtain high-density powders. The average particle size of W powder was 13 μm, Ni powder was 16 μm, Fe powder was 30 μm, and Co powder was 30 μm. The ball-to-powder ratio was 1, the rotation speed was 100 RPM, and the ball milling time was 24 h. The proportions of each component were W: 93 wt.%, Ni: 4.9 wt.%, Fe: 1.4 wt.%, and Co: 0.7 wt.%.

[0067] Adhesive jet printing: A processable 3D model is added to the adhesive jet printing equipment, and the relevant printing parameters are set. The adhesive used consists of acrylic resin (15 vol.%), polyethylene glycol (10 vol.%), deionized water (70 vol.%), and diethylene glycol (5 vol.%). The set printing parameters are: layer thickness 0.05 mm, powder spreading roller translation speed 20 mm / s, powder spreading roller rotation speed 5 r / s, and adhesive saturation 50%.

[0068] Curing: After the green body is printed, the printed area on the printing platform is moved to the drying oven for drying and curing. The drying temperature is 150 ℃ and the drying time is 2 hours.

[0069] Sintering: The solidified powder green body is placed in a crucible and transferred to a microwave sintering furnace for sintering. The sintering temperature is increased from room temperature to 300 ℃ at a rate of 5 ℃ / min and held at 300 ℃ for 1 hour; then increased from 300 ℃ to 450 ℃ at a rate of 2 ℃ / min and held at 450 ℃ for 1 hour; then increased from 450 ℃ to 1440 ℃ at a rate of 10 ℃ / min and held at 1440 ℃ for 30 min. The green body is then cooled in the furnace. A mixture of 90% N2 and 10% H2 by volume is used as the protective gas throughout the sintering process.

[0070] Test: The relative density of the sample is 95.6% ( It has a tensile strength of approximately 694 MPa, an elongation of approximately 7.9%, an HV hardness of 322 (HV10), a compressive strength of 854 MPa, and an impact energy ≥ (As shown in Table 1).

[0071] Comparative Example 2

[0072] Laser selective melting 3D printing

[0073] Mixing: Tungsten, nickel, iron, cobalt powder, anhydrous ethanol, and organic binder were added to a ball mill jar and uniformly mixed using a ball mill to obtain a suspension. The average particle size of W powder was 13 μm, Ni powder was 16 μm, Fe powder was 30 μm, and Co powder was 30 μm. The ball-to-powder ratio was 1, the rotation speed was 100 RPM, and the ball milling time was 24 h. The proportions of each component were W: 93 wt.%, Ni: 4.9 wt.%, Fe: 1.4 wt.%, and Co: 0.7 wt.%. The suspension was spray-dried and sieved to obtain spherical powder particles with an average particle size of 30 μm.

[0074] Selective laser melting 3D printing: Import the 3D model into the equipment and set the laser volume energy density to 1000 J / mm². 3The laser power was set to 450W, the scanning speed to 300 mm / s, the scanning spacing to 50 μm, the layer thickness to 30 μm, and the laser spot diameter to 70 μm. After printing, a printed blank was obtained.

[0075] Test: The relative density of the sample is 97.33% ( The tensile strength is approximately 658 MPa, the elongation is approximately 2.7%, the HV hardness is 384HV10 (as shown in Table 1), the compressive strength is 1524 MPa, and the impact energy is ≥ (As shown in Table 1).

[0076] Table 1. Test data for Examples 1-6 and Comparative Examples 1-2

[0077] relative density % Tensile strength (MPa) Elongation (%) Hardness (HV10) Compressive strength (MPa) <![CDATA[Impact toughness (J / cm 2 )]]> Example 1 98.7 1011 16.7 374 1703 137 Example 2 96.22 674 9 334 1463 76 Example 3 96.54 759 11.3 340 1504 81 Example 4 98.22 966 14.7 361 1655 119 Example 5 98.04 951 14.2 354 1627 112 Example 6 97.91 861 13.1 346 1581 102 Example 7 99 1157 17.8 387 1768 150 Example 8 98.5 987 16.0 366 1684 130 Comparative Example 1 95.60 694 7.9 322 854 85 Comparative Example 2 97.33 658 2.7 384 1524 20

[0078] Based on the performance comparison results of Examples 1 and 4, Examples 5 and 6, and Examples 7 and 8, it can be concluded that reducing the printing line width is beneficial to improving the material performance, and currently 0.4 mm is the optimal line width.

[0079] Based on the performance comparison results of Examples 1 and 5, and Examples 4 and 6, it can be concluded that reducing the printing layer thickness is beneficial to improving material performance, and the current optimal layer thickness is 0.15 mm.

[0080] Based on the performance comparison results of Examples 1 and 7, and Examples 4 and 8, it can be concluded that increasing the printing temperature is beneficial to improving material performance, and the current optimal printing temperature is 190°C.

[0081] Therefore, the optimal critical printing process parameters are a line width of 0.4 mm, a layer thickness of 0.15 mm, and a printing temperature of 190℃.

[0082] Based on the performance comparison results between Example 1 and Example 2, and between Example 1 and Comparative Example 3, it can be concluded that the proportion of different component binders has a significant impact on the performance of the material. Currently, the optimal binder ratio is POM: 88 vol.%, PP: 5.25 vol.%, EVA: 5.25 vol.%, and DOP: 1.5 vol.%, which yields the best performance.

[0083] Comparative Example 1 and Comparative Example 2 represent binder jetting 3D printing and laser selective melting 3D printing processes, respectively. The main reason for the performance difference is the difference in the process.

[0084] The specification and drawings of this invention are intended to be illustrative rather than restrictive. Based on this invention, those skilled in the art can make substitutions and modifications to some of the technical features without creative effort, and all such modifications are within the scope of protection of this invention.

Claims

1. A method for indirect additive manufacturing of high-density tungsten alloy parts, characterized in that, Includes the following steps: S1. 85~98 wt.% W powder, 0~10 wt.% Ni powder, 0~5 wt.% Fe powder or Cu powder and 0~5 wt.% Co powder are uniformly mechanically mixed to obtain a mixed powder; S2. The mixed powder is kneaded with a polymer binder to obtain a feedstock, which is then extruded into filaments using an extruder. The polymeric binder accounts for 40-60 vol.% of the feed ratio; the polymeric binder consists of binder 1 and binder 2; binder 1 accounts for 75-90 vol.% of the total polymeric binder, and binder 2 accounts for 10-25 vol.% of the total polymeric binder; binder 1 is polyoxymethylene (POM), and binder 2 is one or more of stearic acid, paraffin wax, dioctyl phthalate (DOP), ethylene-vinyl acetate copolymer (EVA), and polypropylene (PP); S3. The filament is FDM 3D printed to obtain a printing blank, which is then catalytically degreased, thermally degreased, sintered, and finally heat-treated to obtain an indirect additive manufacturing process for high-density tungsten alloy parts.

2. The preparation method according to claim 1, characterized in that, The average particle size of the W powder is 1-30 μm, the average particle size of the Ni powder is 1-25 μm, the average particle size of the Fe powder is 1-30 μm, the average particle size of the Co powder is 1-30 μm, and the average particle size of the Cu powder is 1-50 μm.

3. The preparation method according to claim 1, characterized in that, The mechanical mixing uses a ball mill with a ball-to-material weight ratio of 0.5 to 3; the spindle speed during ball milling is 2 to 300 RPM; and the milling time is 1 to 48 hours.

4. The preparation method according to claim 1, characterized in that, The mixing process is a intensive mixing process, with a mixing temperature of 140~185℃, a screw speed of 3-50RPM, and a mixing time of 30~120 min.

5. The preparation method according to claim 1, characterized in that, During the extrusion process of the extruder, the screw speed is 20~50 RPM; the extrusion temperature is 150~195 ℃; the extrusion pressure is 3~15 MPa; and the extruded filament specifications are 1.75±0.5mm or 2.85±0.75mm.

6. The preparation method according to claim 1, characterized in that, During the FDM 3D printing process, the nozzle diameter is 0.25~0.8 mm; the platform temperature is 120~200 ℃; the printing temperature is 170~225 ℃; and the printing speed is 30~90 mm / s. The printing layer thickness is 0.1~0.4 mm; the printing line width is 0.3~0.8 mm; the printing gear clamping distance is 1.0~2.0 mm; the printing fill density is 60~150%; the printing fill method is one or more of the following: straight line, zigzag line, concentric circle, triangle, square, polygon.

7. The preparation method according to claim 1, characterized in that, The catalysts for the catalytic degreasing are oxalic acid, nitric acid, formic acid, zeolite catalyst HZSM-5, and zirconium sulfate SO4. 2- One of the ZrO2 types; During the catalytic degreasing process, the furnace temperature is 100~150 ℃ and the holding time is 30~360 min; the vaporization box temperature is 140~180 ℃; the furnace atmosphere is nitrogen or argon with a flow rate of 30~150 L / min; and the acid inlet rate is 0.5~10 g / min.

8. The preparation method according to claim 1, characterized in that, During the thermal stripping process, the heating rate is 1-10 °C / min for the 30-600 °C stage, and the holding time is 60-720 min; the heating rate is 1-10 °C for the 600-1100 °C stage, and the holding time is 60-480 min; the furnace atmosphere is nitrogen or argon, with a flow rate of 2-30 m³ / min. 3 / h.

9. The preparation method according to claim 1, characterized in that, During the sintering process, the heating rate from 0 to 600 ℃ is 5 ℃ / min, and the holding time is 30 to 720 min; the heating rate from 600 to 1200 ℃ is 2 to 5 ℃, and the holding time is 30 to 180 min; the heating rate from 1200 to 1500 ℃ is 0.5 to 5 ℃ / min, and the holding time is 30 to 240 min; the furnace atmosphere is hydrogen, and the hydrogen flow rate is 5 to 20 m³ / min. 3 / h.

10. The preparation method according to claim 1, characterized in that, The heat treatment is oil quenching, with an oil quenching temperature of 800~1500 ℃ and a holding time of 30~120 min; during the oil quenching process, the cooling rate is 30~120 ℃ / s.

Images