A cemented carbide additive manufacturing method with uniform shrinkage in all directions

Abstract

The present invention relates to a method for additive manufacturing of cemented carbide with uniform shrinkage in all directions, and belongs to the technical field of cemented carbide and additive manufacturing. The present invention adopts WC-Co powder and adhesive to prepare printing feed, and adopts fused deposition molding to print cemented carbide green body; through the pioneering low-temperature hot isostatic pressing process, the printed green body is subjected to low-temperature hot isostatic pressing treatment, which can uniformly densify the cemented carbide green body and effectively eliminate the internal pores of the green body; then, the cemented carbide green body is degreased and sintered to obtain a cemented carbide three-dimensional solid part with high relative density, uniform shrinkage in all directions and high dimensional accuracy. The present invention combines additive manufacturing with degreasing and sintering process, and the prepared cemented carbide three-dimensional solid part has high relative density, uniform shrinkage in all directions and no metallurgical defects. The method has low requirements for powder raw materials, can effectively reduce the production cost of WC-Co cemented carbide parts with complex shapes, and is suitable for large-scale batch industrial promotion.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a cemented carbide additive material with uniform shrinkage in all directions, and belongs to the technical field of cemented carbide and additive material manufacturing. Background Art

[0002] Cemented carbide is a composite material made of a refractory metal hard compound and a binder metal through powder metallurgy. It is a metal-ceramic composite material with high hardness, wear resistance, compressive strength, and elastic modulus. Known as the "teeth of industry," it has extensive applications in aerospace, resource mining, equipment manufacturing, rail transportation, and electronic information technology. Currently, powder metallurgy processes are unable to meet the demand for the production of complex cemented carbide components. Additive manufacturing provides a new technical approach for the preparation of complex cemented carbide components.

[0003] At present, the additive manufacturing methods used in cemented carbide mainly include: powder bed fusion (PBF) thermoforming additive manufacturing methods such as selective laser melting (SLM), selective laser sintering (SLS) and selective electron beam melting (SEBM), as well as cold forming additive manufacturing methods such as photo-stereolithography 3D printing, binder jet additive manufacturing (BJAM), gel 3D printing (3DGP) and fused deposition modeling (FDM). Uhlmann et al. [E.Uhlmann, A.Bergmann, W.Gridin, Investigation on additive manufacturing of tungsten carbide-cobalt by selective laser melting, Procedia CIRP.35(2015)8-15.] prepared WC-Co cemented carbide by SLM with a relative density of 98.8%, but the sample produced a ternary phase; Xiao Meng [Xiao Meng. Preparation of spherical WC-Co powder by radio frequency plasma spheroidization and study of its 3D printing microstructure and properties [D]. Kunming: Kunming University of Science and Technology, 2021.] prepared WC-30%Co cemented carbide by SEBM process with a relative density of 57.24-89.22%. After hot isostatic pressing treatment, the relative density of the sample reached 95%. Enneti et al. [RKEnneti, KCPrough, Wear properties of sintered WC-12%Coprocessed via Binder Jet 3D Printing (BJ3DP), International Journal of Refractory Metals & Hard Materials. 78 (2019) 228-232] used BJAM to prepare WC-12%Co cemented carbide green bodies. After vacuum sintering at 1435-1485 °C, the density of the sintered samples was 13.1-13.5 g / cm 3 , the relative density is up to 94%; the printed green body is sintered and hot isostatically pressed, and the sample density is 14.1-14.2g / cm 3, with a maximum relative density of 99% and a dimensional shrinkage rate of 22-27% in different directions. Chinese patent CN201680084484.X discloses a method for 3D printing of cermets or cemented carbides, involving a powder for 3D printing a cermet or cemented carbide blade body, the powder comprising 30% to 70% by volume of particles with a diameter of less than 10 μm; and a method for manufacturing a cermet or cemented carbide blade body using a BJAM method, comprising: forming the powder, using the powder to 3D print the blade body together with a printing binder to form a 3D-printed cermet or cemented carbide green body, and then sintering the green body to form a cermet or cemented carbide blade body. The cermet or cemented carbide blade body prepared in this patent has a porosity of 3-13%. Chinese patent CN202210239428.6 discloses a method for preparing three-dimensional structural cemented carbide using photocuring 3D printing. Water-soluble tungsten salt is used as a tungsten source and water-soluble cobalt salt is used as a cobalt source to prepare a printable ink. Photocuring is used to print a three-dimensional structural blank, which is then treated with a high-temperature post-treatment process to finally obtain a three-dimensional structural cemented carbide. However, the patent does not disclose the relative density and sintering size shrinkage rate of the prepared cemented carbide sample. Lengauer et al. [W. Lengauer, I. Duretek, M. Fürst, V. Schwarz, J. Gonzalez-Gutierrez, S. Schuschnigg, C. Kukla, M. Kitzmantel, E. Neubauer, C. Lieberwirth, V. Morrison, Fabrication and properties of extrusion-based 3D-printed hardmetal and cermet components, International Journal of Refractory Metals & Hard Materials. 82 (2019) 141-149.] used FDM-debinding sintering process to prepare WC-10% Co carbide indexable inserts. The printed green samples had dense pores in the construction direction (Z direction), and the study did not report the relative density of the sintered samples. The shrinkage rate of the sintered samples in the X and Y directions was 20.6-21%, and the dimensional shrinkage rate in the Z direction was 22-23.4%.Kim et al. [Material extrusion-based three-dimensional printing of WC-Co alloy with a paste prepared by powder coating, Additive Manufacturing. 52 (2022) 102679.] used 3DGP-debinding sintering process to prepare WC-10% Co with a relative density of 99% and an isotropic dimensional shrinkage of 18-20%.

[0004] The above search found that PBF thermoforming additive manufacturing methods such as SLM and SEBM have high requirements on the performance of raw material powders, such as high powder sphericity, good fluidity, high loose density, and narrow particle size distribution; the prepared samples have a large number of metallurgical defects such as pores and cracks that are difficult to eliminate, and have low relative density; decarburization reactions are prone to occur, resulting in brittle phases.

[0005] The BJAM method uses a powder bed method similar to PBF. The performance requirements for the raw material powder are the same as those of PBF, requiring the powder to have high sphericity, good fluidity, high apparent density, and a narrow particle size distribution. The prepared cemented carbide parts have simple shapes, low relative density, and high porosity. The relative density of cemented carbide samples prepared by the 3DGP method has been improved, but the problem of uneven sintering shrinkage in all directions still exists. Cemented carbides prepared by light-curing 3D printing also have the problem of low relative density. The cemented carbide prepared by the FDM-debinding sintering process has process characteristics that lead to problems such as large-sized wedge-shaped or diamond-shaped pores, interlayer cracks, and uneven dimensional shrinkage, and has a low relative density.

[0006] In response to the above problems, the present invention designs a method for preparing cemented carbide with high relative density and uniform shrinkage in all directions. First, a high powder loading printing feed is prepared; second, an FDM printing process is designed to prepare high relative density green bodies, eliminating the porosity defects of the printed green bodies and preparing green bodies with higher relative density; third, a low-temperature hot isostatic pressing process for green bodies is designed to further uniformly densify the green bodies without changing the shape of the green bodies, thereby improving the relative density of the green bodies and maintaining dimensional accuracy; finally, degreasing and sintering are performed to obtain cemented carbide products with high relative density and uniform dimensional shrinkage in all directions. Summary of the Invention

[0007] The present invention provides a method for additive manufacturing of cemented carbide with uniform shrinkage in all directions. First, a printing feed with a high powder loading is prepared; second, a green body is prepared by FDM printing; third, the green body is subjected to low-temperature hot isostatic pressing to obtain a green body with high relative density and precise dimensions; and finally, the green body is degreased and sintered to obtain a cemented carbide product with high relative density and uniform shrinkage in all directions. The method specifically comprises the following steps:

[0008] (1) Mixing and preparing printing feed:

[0009] The WC-Co powder A and the binder B are mixed according to the designed ratio, and the mixture is put into a banbury mixer for banbury mixing to prepare a banbury mixture C in which the WC-Co powder and the binder B are uniformly banbury mixed.

[0010] The prepared banburying mixture C is fed into a granulator to prepare a granular printing feed D with uniform size and a particle size of 1-4 mm;

[0011] (2) FDM printing to prepare green parts:

[0012] The granular printing feed D obtained in step (1) is used as a raw material, and a fused deposition modeling (FDM) device is used to print and prepare a cemented carbide printing green body E;

[0013] (3) Hot isostatic pressing: The green body E prepared in step (2) is subjected to low-temperature hot isostatic pressing in an inert atmosphere to obtain a cemented carbide green body F with high relative density and good dimensional accuracy;

[0014] (4) Solvent degreasing of green body: first, n-heptane is heated to a set temperature, and then the cemented carbide green body F treated in step (3) is placed in the heated n-heptane for soaking and degreasing, and then taken out and vacuum dried to obtain a solvent degreased green body G;

[0015] The soaking and degreasing time is determined according to the size of the green body; the drying temperature and time are determined according to the characteristic temperatures of the adhesive and n-heptane;

[0016] (5) Thermal debinding and sintering: The green body G prepared in step (4) is subjected to thermal debinding and sintering to obtain a WC-Co cemented carbide solid part H.

[0017] Wherein, the particle size D of the WC-Co powder A in step (1) is 50 Less than 20μm; the volume proportion of WC-Co powder A in the internal mixing mixture C is 45-65%, and the volume proportion of binder B is 35-55%. Here, the volume proportion of A in C is defined as the powder loading.

[0018] All commercial raw material powders used for preparing cemented carbide can be used in the present invention.

[0019] Among them, the difficulty of designing the adhesive B in step (1) is how to ensure a high loading amount of powder A in the banburying mixture C while making the printing feed D have the shear thinning characteristics of a pseudoplastic fluid to meet the requirements of 3D printing; in addition, the printing feed D must have good temperature stability and thermoplasticity to ensure that the printing feed D has a wide printing process window; in addition, the printing green body prepared using the printing feed D as a raw material must have high strength to avoid crack defects during low-temperature hot isostatic pressing and degreasing. The present invention optimizes the design of the composition of the adhesive B, and the adhesive B includes a skeleton component, a plasticizing component and a dispersing component; the skeleton component is at least one of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, polyacetal, etc.; the plasticizing component includes at least one of paraffin wax, microcrystalline wax, beeswax, palm wax, etc.; the dispersing component is at least one of stearic acid and stearate. The volume proportion of the plasticizing component in the adhesive B is 35-65%, the volume proportion of the skeleton component is 30-50%, and the volume proportion of the dispersing component is 1-15%.

[0020] The parameters of the internal mixer in step (1) are as follows: the mixing temperature is 120-200° C., the rotation speed is 30-90 rpm, and the stirring time is greater than 30 min.

[0021] Preferably, the adhesive B contains stearic acid, polyethylene, polypropylene, and paraffin wax, and the volume ratio is stearic acid: polyethylene: polypropylene: paraffin wax = 7-12:18-22:18-22:40-55.

[0022] As a further preference, the adhesive B is composed of stearic acid, polyethylene, polypropylene, and paraffin, and the volume ratio is stearic acid: polyethylene: polypropylene: paraffin = 8-12:18-22:18-22:45-55.

[0023] Preferably, the adhesive B contains stearic acid, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and paraffin wax; in the wax-based adhesive, the volume ratio of stearic acid: polyethylene: polypropylene: polymethyl methacrylate: polystyrene: paraffin wax is 7-12:7-12:7-12:6-12:6-12:40-55.

[0024] As a further preferred embodiment, the adhesive B is composed of stearic acid, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and paraffin; by volume ratio,

[0025] Stearic acid: polyethylene: polypropylene: polymethyl methacrylate: polystyrene: paraffin = 8-10:9-11:9-11:7-9:7-9:43-48. Or

[0026] Adhesive B is composed of stearic acid, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and paraffin wax; by volume ratio, stearic acid: polyethylene: polypropylene: polymethyl methacrylate: polystyrene: paraffin wax = 10-12:10-12:10-12:10-12:10-12:53-58. Or

[0027] Adhesive B is composed of stearic acid, polyethylene, polypropylene, polymethyl methacrylate, polystyrene, and paraffin wax; calculated by volume, the ratio of stearic acid: polyethylene: polypropylene: polymethyl methacrylate: polystyrene: paraffin wax is 7.5-8.5:7.5-8.5:7.5-8.5:7.5-8.5:7.5-8.5:40-42.

[0028] The preparation parameters of the 3D printing feed D in step (1) are set as follows: screw speed 30-80 rpm, screw pressure 3-10 kg, and particle diameter 1-4 mm.

[0029] The cemented carbide green body E in step (2) is produced by printing the granular printing feed D prepared in step (1) using an FDM device. The printing process is as follows: a three-dimensional CAD model is created on a computer according to the part shape; the model is sliced ​​and layered using software and imported into an additive manufacturing numerical control system; the granular printing feed D is heated by the numerical control system, and the granular material is extruded using a screw and formed layer by layer according to the slicing route until the printed green body E is obtained.

[0030] Wherein, the 3D printing technology described in step (2) is FDM. The difficulty lies in designing and optimizing the 3D printing process parameters to reduce defects (such as wedge-shaped or diamond-shaped pores, interlayer cracks, etc.) in the cemented carbide green body E. After optimization, the specific process parameters that can be selected in the present invention are: nozzle diameter of 0.2-0.8mm, nozzle temperature of 120-200℃, layer thickness of 0.1-0.8mm, printing speed of 25-50mm / s, filling rate of 50-130%, microwire overlap ratio of 1-60%, preferably 1-40%, more preferably 4-35%, filling mode of [0,90°], [45°,-45°], or a combination of the two filling modes (i.e., after completing the stacking of the previous layer, the stacking strategy of the next layer should be rotated 45 degrees). Under the synergistic effect of the above parameters, the probability of defects in the green body E is reduced as much as possible.

[0031] The microfilament overlap ratio described in the present invention is defined as the ratio of the overlap amount of two adjacent feeding extrusion belts to the bandwidth, where the bandwidth is the inner diameter of the nozzle.

[0032] The difficulty in the hot isostatic pressing process described in step (3) lies in, on the one hand, achieving effective and uniform densification of the printed green body, reducing or eliminating porosity in the printed green body, while ensuring the dimensional accuracy of the printed green body; on the other hand, minimizing the generation of internal defects in the printed green body. The specific parameters that can be selected after optimization are: heating the hot isostatic press to 50-200°C in an inert atmosphere and maintaining the temperature.

[0033] Preferably, in the hot isostatic pressing process of step (3), the pressure ranges of 5-10MPa, 10-40MPa, and 40-100MPa should be reached at different pressure increasing rates, and the corresponding pressure increasing rates are 1-5MPa / min, 1-5MPa / min, and 1-10MPa / min; in an inert atmosphere, the hot isostatic pressing temperature is cooled to room temperature, and the pressure is reduced from the maximum pressure to the corresponding pressure ranges of 40-60MPa, 20-40MPa, and 5-20PMa at different pressure decreasing rates, and the corresponding pressure decreasing rates are 1-10MPa / min, 1-5MPa / min, and 1-5MPa / min, and finally, the pressure is naturally reduced from 10MPa or 5MPa to normal pressure. The maximum pressure of hot isostatic pressing does not exceed 100MPa, and the holding time at the maximum pressure is 10min-60min.

[0034] The inert gas should be nitrogen, helium, argon, or a mixture thereof, with a purity of 99.99 wt %, wherein the oxygen content is less than 0.0001 wt %.

[0035] Among them, the difficulty in the solvent degreasing process of step (4) is that it is necessary to design the degreasing temperature and degreasing time of n-heptane according to the composition of the adhesive to improve the degreasing efficiency; at the same time, it is necessary to avoid the cracking of the printed green body due to the swelling of the polymer components in the adhesive. After testing, the specific parameters or steps are as follows: first, the n-heptane is heated and kept warm at a certain temperature, and then the cemented carbide green body F treated in step (3) is placed in the n-heptane and soaked for 4-30 hours. After the soaking is completed, the cemented carbide green body F is taken out and placed in a drying furnace at a temperature of 40-80°C for drying to obtain a solvent degreased green body G. The specific parameters are: the holding temperature of n-heptane is 15-80°C, preferably 20-60°C; the soaking time is 4-30 hours, preferably 8-20 hours; the drying temperature is 40-80°C, preferably 40-60°C; the drying time is 3-14 hours, preferably 6-8 hours.

[0036] Wherein, in said step (5), said high temperature treatment is divided into two stages. Among them, the first stage is a medium-low temperature thermal debinding stage, with a temperature range of 400-750°C. In the first stage, a reducing atmosphere is used, and the temperature is heated from room temperature to the first temperature at a heating rate of 0.1-8°C / min. The second stage is a high temperature sintering and heat preservation stage, with a temperature range of 750-1500°C. In the second stage, a vacuum atmosphere is used, and the temperature is heated from a temperature greater than the first temperature to a second temperature at a heating rate of 0.5-20°C / min.

[0037] Preferably, the heating rate in the first stage is 0.1-6°C / min, and the heating rate in the second stage is 0.5-15°C / min; further preferably, the heating rate in the first stage is 0.3-5°C / min, and the heating rate in the second stage is 1-10°C / min.

[0038] The present invention proposes a feasible method for preparing cemented carbide with uniform isotropic shrinkage. The method combines a plasticizing component, a skeleton component, and a dispersing component, and uses WC-Co powder as a raw material to prepare a print feed having the shear-thinning characteristics of a pseudoplastic fluid. Furthermore, the print feed has high temperature stability in its rheological properties, enabling green body printing to be performed over a wide temperature range. Furthermore, the plasticizing component designed into the binder can increase the powder loading of the print feed prepared using the binder, thereby improving the density of the final part. Furthermore, the print feed must be thermoplastic, so that when the printed green body is densified by low-temperature hot isostatic pressing, the green body can be uniformly densified, eliminating or reducing pores and cracks in the printed green body, while also avoiding the generation of new defects in the printed green body. The present invention uses fused deposition modeling (3D) printing equipment and optimizes printing process parameters to reduce porosity and crack defects in WC-Co cemented carbide printed green bodies. Subsequently, a low-temperature hot isostatic pressing (HIP) process is designed based on the properties of the binder to uniformly densify the green bodies and avoid bubbling and cracking defects caused by large-scale cracking of the binder. Finally, a suitable debinding and sintering process is designed based on the composition of the various components of the binder to produce cemented carbide solid parts with high relative density and uniform shrinkage in all directions.

[0039] Advantages and positive effects of the present invention:

[0040] (1) The present invention discloses a method for manufacturing cemented carbide with uniform shrinkage in all directions. Through the synergistic effect of various steps and their process parameters, a complex-shaped cemented carbide product with high relative density and uniform shrinkage in all directions can be prepared. The prepared product has no porosity and crack defects, no decarburization, no brittle phase, high relative density and uniform shrinkage in all directions. It effectively solves the problems of cracking, porosity and uneven shrinkage that have long plagued cemented carbide additive manufacturing and are difficult to solve by existing additive manufacturing processes. There are no special requirements for raw material powder, the preparation method is simple, the cost is low, and it is easy to mass produce.

[0041] (2) The present invention can use WC-Co powder without special requirements as raw material, including various powders and waste powder materials generated in the production process, and the skeleton components, plasticizing components and dispersing components used in the adhesive are easy to obtain, low cost, and suitable for industrial promotion and application; in particular, the optimized adhesive of the present invention can not only reduce the requirements for WC-Co raw material powder, but also ensure that the printed green body meets the performance requirements of subsequent processing.

[0042] (3) In order to solve the problem that wedge-shaped or diamond-shaped pores are easily formed in the fused deposition modeling printing process, the present invention eliminates the wedge-shaped or diamond-shaped pores in the green body through the synergistic effect of printing process parameters, adhesive optimization and low-temperature hot isostatic pressing, and prepares high relative density cemented carbide complex shape green bodies.

[0043] (4) Based on the printing feeding characteristics designed in the present invention, a low-temperature hot isostatic pressing densification process for green bodies was developed, which enables the printed green bodies to be uniformly densified while maintaining the dimensional accuracy of the printed green bodies and avoiding defects in the green bodies caused by various reasons.

[0044] (5) The two-step degreasing combined with sintering process is used to prepare samples that are nearly fully dense (relative density greater than 99.5%), with uniform shrinkage in all directions. After optimizing the process parameters, the fluctuation range of the shrinkage rate in all directions is less than 1%, and after optimization, the range can be less than 0.6%. WC-Co cemented carbide solid parts are free of metallurgical defects, decarburization, and brittle phases. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of stacking of feed materials according to the present invention and schematic diagram of stacking of feed materials after optimizing process parameters (eliminating defects in green compacts).

[0046] Figure 2 This is a vertical cross-sectional SEM image of a cemented carbide green body according to Example 1 of the present invention.

[0047] Figure 3 This is a metallographic microscope image of a cemented carbide sample after degreasing and sintering according to Example 1 of the present invention (before corrosion).

[0048] Figure 4 This is a metallographic microscope image of a cemented carbide sample after degreasing and sintering according to Example 1 of the present invention (after corrosion).

[0049] Figure 5 This is a macroscopic structural photograph of a cemented carbide sample prepared by 3D printing using the method described in the present invention.

[0050] Figure 6 This is a SEM image of a vertical cross-section of a cemented carbide green body of comparative example 1 of the present invention.

[0051] The present invention will be described in further detail below with reference to specific embodiments. However, it should be understood that these embodiments are intended to illustrate and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims of this application.

[0052] The present invention proposes a feasible method for preparing cemented carbide by 3D printing, which combines 3D printing with degreasing and sintering process, and can prepare cemented carbide with high relative density, uniform shrinkage in all directions and no obvious metallurgical defects. First, the step (1) described in the present invention can be used to prepare a printing feed with suitable viscosity, uniform powder dispersion, shear thinning characteristics, relatively high powder loading and good printability. By using the optimized process parameters in step (2) described in the present invention, the wedge-shaped or diamond-shaped holes in the printed green body can be reduced or reduced. The cemented carbide green body prepared by the low-temperature hot isostatic pressing process in step (3) described in the present invention has a good appearance, and its vertical section optical micrograph is as follows: Figure 2 As shown, the microstructure is observed. The vertical section of the cemented carbide green body has no interlayer cracking defects and no obvious wedge-shaped holes in the green body. That is, by optimizing the printing process parameters and using hot isostatic pressing equipment to densify the cemented carbide green body, the pores in the cemented carbide green body can be effectively eliminated, the interlayer bonding strength in the cemented carbide green body can be improved, and a high-quality cemented carbide green body can be prepared. The metallographic microscope image and macroscopic structure photo of the cemented carbide sample after the step (5) of the present invention are shown in FIG. Figure 3 、 Figure 4 and Figure 5 As shown, it can be observed that the microstructure of the cemented carbide sample after degreasing and sintering is uniform, without Co pool, brittle phase, metallurgical defects, high relative density (up to 99.7% after optimization), and good macroscopic shape. DETAILED DESCRIPTION

[0053] Example 1:

[0054] (1) Prepare WC-Co cemented carbide powder by ball mill, particle size D 50 0.5-10μm, composed of 91wt.% WC and 9wt.% Co, 1.45kg is measured for standby use; at room temperature, 10cm 3 Stearic acid, 20cm 3 Polyethylene, 20cm 3 Polypropylene, 50cm 3 Wax is ready for use. Heat the internal mixer to 160℃ and mix 10cm 3 Stearic acid, 20cm 3 Polyethylene, 20cm 3 Polypropylene, 50cm3 Paraffin wax and 1.45 kg WC-Co powder were added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 160°C, rotation speed of 60 rpm, and stirring time of 100 min to prepare a WC-Co internal mixing mixture with a powder loading of 50 vol.%.

[0055] The obtained mixed material was placed in a pelletizer, and the screw speed was set to 60 rpm, the pressure was 10 kg, and the temperature was 110° C. Granular printing feed with a particle size of about 2-3 mm was obtained.

[0056] (2) Using the granular printing feed obtained in step (1) as raw material, a fused deposition modeling device is used to form a cemented carbide green body through 3D printing technology. The parameters are set as follows: nozzle diameter is 0.5 mm, nozzle temperature is 160°C, layer thickness is 0.2 mm, printing speed is 40 mm / s, microfilament overlap ratio is 15%, extrusion flow is 100%, filling rate is 100%, and [0,90°] is used as the 3D printing routing mode.

[0057] (3) Hot isostatic pressing is performed on the cemented carbide green body printed in step (2). The cemented carbide green body prepared in step (3) is placed in a hot isostatic press. Under an inert atmosphere, the hot isostatic press is heated to 150°C and kept warm. Subsequently, the press is pressurized to 10MPa, 30MPa, and 60MPa at a pressure increase rate of 2MPa / min, 5MPa / min, and 10MPa / min, respectively. The pressure is maintained at 60MPa for 45 minutes, and the hot isostatic press is cooled to room temperature. Subsequently, the pressure is reduced to 30MPa, 20MPa, and 5MPa at a pressure reduction rate of 5MPa / min, 5MPa / min, and 2MPa / min. When the pressure drops to 5MPa, the press is unloaded to normal pressure.

[0058] (4) The cemented carbide green body treated in step (3) is immersed in n-heptane liquid and sealed, and then the n-heptane solution is heated to 40° C. in a water bath and kept warm for about 14 hours to remove the binder in the cemented carbide green body.

[0059] (5) After the cemented carbide green body treated in step (4) was dried in a drying furnace at 50°C for 6 hours, the green body was placed in hydrogen, heated to 550°C at a heating rate of 0.5°C / min and kept warm for 1 hour, then heated to 1100°C at a heating rate of 5°C / min under vacuum conditions, and finally heated to 1430°C at a heating rate of 10°C / min in an argon atmosphere and kept warm for 90 minutes.

[0060] The printing feed prepared using these parameters exhibits the shear-thinning characteristics of a pseudoplastic fluid, demonstrating excellent printability. By appropriately matching the printing parameters with the hot isostatic pressing (HIP) parameters, wedge-shaped or diamond-shaped pores in the cemented carbide green body are significantly eliminated, achieving a relative density of 98.8% for the green body and 99.7% for the sintered body after debinding and sintering. Metallographic microscopy revealed porosity of A02B00, uncombined carbon of C00, and η phase of E00. The dimensional shrinkage of the sintered sample in the X, Y, and Z directions was 17.51%, 17.54%, and 17.97%, respectively. The shrinkage was relatively uniform in all directions, and the sample exhibited no noticeable warping.

[0061] Example 2:

[0062] (1) Prepare WC-Co cemented carbide powder by ball mill, particle size D 50 0.5-10μm, composed of 90wt.% WC and 10wt.% Co, 1.5kg is measured for standby use; at room temperature, 9cm 3 Stearic acid, 10cm 3 Polyethylene, 10cm 3 Polypropylene, 8cm 3 Polymethyl methacrylate, 8cm 3 Polystyrene, 45cm 3 Wax is ready for use. Heat the internal mixer to 140℃ and add 9cm 3 Stearic acid, 10cm 3 Polyethylene, 10cm 3 Polypropylene, 8cm 3 Polymethyl methacrylate, 8cm 3 Polystyrene, 45cm 3 Paraffin wax and 1.5 kg WC-Co powder were added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 140°C, rotation speed of 60 rpm, and stirring time of 100 min to prepare a WC-Co internal mixing mixture with a powder loading of 55 vol.%.

[0063] The obtained mixed material was placed in a pelletizer, and the screw speed was set to 60 rpm, the pressure was 10 kg, and the temperature was 110° C. Granular printing feed with a particle size of about 2-3.5 mm was obtained.

[0064] (2) Using the granular printing feed obtained in step (1) as raw material, a fused deposition modeling device is used to form a cemented carbide green body through 3D printing technology. The parameters are set as follows: nozzle diameter is 0.8 mm, nozzle temperature is 140°C, layer thickness is 0.3 mm, printing speed is 45 mm / s, microfilament overlap ratio is 5%, extrusion flow rate is 90%, filling rate is 90%, and [45°, 45°] is used as the 3D printing routing method.

[0065] (3) The cemented carbide green body printed in step (2) is subjected to hot isostatic pressing. The cemented carbide green body prepared in step (3) is placed in a hot isostatic press. Under an inert atmosphere, the hot isostatic press is heated to 120°C for heat preservation. Subsequently, the press is pressurized to 20MPa, 50MPa, and 100MPa at a pressure increase rate of 3MPa / min, 5MPa / min, and 10MPa / min, respectively. The pressure is maintained at 100MPa for 30min, and the hot isostatic press is cooled to room temperature. Subsequently, the pressure is reduced to 60MPa, 20MPa, and 10MPa at a pressure reduction rate of 10MPa / min, 5MPa / min, and 3MPa / min. When the pressure drops to 10MPa, the press is unloaded to normal pressure.

[0066] (4) The cemented carbide green body treated in step (3) is immersed in n-heptane liquid and sealed, and then the n-heptane solution is heated to 45° C. in a water bath and kept warm for about 12 hours to remove the binder in the cemented carbide green body.

[0067] (5) After the cemented carbide green body treated in step (4) was dried in a drying furnace at 55°C for 6 hours, the green body was placed in hydrogen, and the temperature was increased to 650°C at a heating rate of 0.5°C / min and kept warm for 1 hour. The temperature was then increased to 1120°C at a heating rate of 5°C / min under vacuum conditions, and finally increased to 1450°C at a heating rate of 10°C / min in an argon atmosphere and kept warm for 45 minutes.

[0068] The printing feed prepared using these parameters exhibits the shear-thinning characteristics of a pseudoplastic fluid, resulting in excellent printability. By properly matching printing parameters with hot isostatic pressing (HIP) parameters, the wedge-shaped or diamond-shaped pores in the cemented carbide green body are effectively reduced, achieving a relative density of 97.8%. After debinding and sintering, the relative density of the sintered sample reaches 99.2%. Furthermore, the dimensional shrinkage of the sintered sample in the X, Y, and Z directions is 18.34%, 18.24%, and 19.89%, respectively.

[0069] Example 3:

[0070] (1) Prepare WC-Co cemented carbide powder by ball mill, particle size D 500.5-10μm, composed of 80wt.% WC and 20wt.% Co, 1.245kg is measured for standby use; at room temperature, 11cm 3 Stearic acid, 11cm 3 Polyethylene, 11cm 3 Polypropylene, 11cm 3 Polymethyl methacrylate, 11cm 3 Polystyrene, 55cm 3 Wax is ready for use. Heat the internal mixer to 130℃ and mix 11cm 3 Stearic acid, 11cm 3 Polyethylene, 11cm 3 Polypropylene, 11cm 3 Polymethyl methacrylate, 11cm 3 Polystyrene, 55cm 3 Paraffin was prepared and 1.245 kg of WC-Co powder was added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 130°C, rotation speed of 60 rpm, and stirring time of 100 min. A WC-Co internal mixing mixture with a powder loading of 45 vol.% was prepared.

[0071] The obtained mixed material was placed in a pelletizer, and the screw speed was set to 60 rpm, the pressure was 10 kg, and the temperature was 120° C. Granular printing feed with a particle size of about 2-3.5 mm was obtained.

[0072] (2) Using the granular printing feed obtained in step (1) as raw material, a fused deposition modeling device is used to form a cemented carbide green body through 3D printing technology. The parameters are set as follows: nozzle diameter is 0.4 mm, nozzle temperature is 130°C, layer thickness is 0.4 mm, printing speed is 30 mm / s, microfilament overlap ratio is 0%, extrusion flow rate is 90%, filling rate is 90%, and [45°, 45°] is used as the 3D printing routing method.

[0073] (3) The cemented carbide green body printed in step (2) is subjected to hot isostatic pressing. The cemented carbide green body prepared in step (3) is placed in a hot isostatic press. Under an inert atmosphere, the hot isostatic press is heated to 130°C for heat preservation, and then pressurized to 30MPa, 50MPa, and 120MPa at a pressure increase rate of 2MPa / min, 5MPa / min, and 10MPa / min, respectively. The pressure is maintained at 120MPa for 20min, and the hot isostatic press is cooled to room temperature. The pressure is then reduced to 60MPa, 30MPa, and 10MPa at a pressure reduction rate of 10MPa / min, 5MPa / min, and 2MPa / min. When the pressure drops to 10MPa, the pressure is unloaded to normal pressure.

[0074] (4) The cemented carbide green body treated in step (3) is immersed in n-heptane liquid and sealed, and then the n-heptane solution is heated to 35° C. in a water bath and kept warm for about 16 hours to remove the binder in the cemented carbide green body.

[0075] (5) After the cemented carbide green body treated in step (4) was dried in a drying furnace at 55°C for 8 hours, the green body was placed in hydrogen, heated to 500°C at a heating rate of 0.5°C / min and kept warm for 1 hour, then heated to 1000°C at a heating rate of 5°C / min under vacuum conditions, and finally heated to 1480°C at a heating rate of 10°C / min in an argon atmosphere and kept warm for 45 minutes.

[0076] The printing feed prepared using these parameters exhibits the shear-thinning characteristics of a pseudoplastic fluid, resulting in excellent printability. By properly matching printing parameters with hot isostatic pressing (HIP), the wedge-shaped or diamond-shaped pores in the cemented carbide green body are effectively reduced, achieving a relative density of 96.5%. After debinding and sintering, the relative density of the sintered sample reaches 99.3%. Furthermore, the dimensional shrinkage of the sintered sample in the X, Y, and Z directions is 18.22%, 18.14%, and 20.01%, respectively.

[0077] Example 4:

[0078] (1) Prepare WC-Co cemented carbide powder by ball mill, particle size D 50 0.5-10μm, composed of 80wt.% WC and 20wt.% Co, 1.245kg is measured for standby use; at room temperature, 11cm 3 Stearic acid, 11cm 3 Polyethylene, 11cm 3 Polypropylene, 11cm 3 Polymethyl methacrylate, 11cm 3 Polystyrene, 55cm 3 Wax is ready for use. Heat the internal mixer to 130℃ and mix 11cm 3 Stearic acid, 11cm 3 Polyethylene, 11cm 3 Polypropylene, 11cm 3 Polymethyl methacrylate, 11cm 3 Polystyrene, 55cm 3 Paraffin was prepared and 1.245 kg of WC-Co powder was added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 130°C, rotation speed of 60 rpm, and stirring time of 100 min. A WC-Co internal mixing mixture with a powder loading of 45 vol.% was prepared.

[0079] The obtained mixed material was placed in a pelletizer, and the screw speed was set to 60 rpm, the pressure was 6 kg, and the temperature was 120° C. Granular printing feed with a particle size of about 2-3.5 mm was obtained.

[0080] (2) Using the granular printing feed obtained in step (1) as raw material, a fused deposition modeling device is used to form a cemented carbide green body through 3D printing technology. The parameters are set as follows: nozzle diameter is 0.4 mm, nozzle temperature is 130°C, layer thickness is 0.1 mm, printing speed is 25 mm / s, microfilament overlap ratio is 15%, extrusion flow rate is 70%, filling rate is 70%, and [45°, 45°] is used as the 3D printing routing method.

[0081] (3) The cemented carbide green body printed in step (2) is subjected to hot isostatic pressing. The cemented carbide green body prepared in step (3) is placed in a hot isostatic press. Under an inert atmosphere, the hot isostatic press is heated to 150°C for heat preservation. Subsequently, the press is pressurized to 30MPa, 50MPa, and 60MPa at a pressure increase rate of 3MPa / min, 6MPa / min, and 9MPa / min, respectively. The pressure is maintained at 60MPa for 40min, and the hot isostatic press is cooled to room temperature. Subsequently, the pressure is reduced to 40MPa, 20MPa, and 10MPa at a pressure reduction rate of 9MPa / min, 6MPa / min, and 3MPa / min. When the pressure drops to 10MPa, the press is unloaded to normal pressure.

[0082] (4) The cemented carbide green body treated in step (3) is immersed in n-heptane liquid and sealed, and then the n-heptane solution is heated to 35° C. in a water bath and kept warm for about 16 hours to remove the binder in the cemented carbide green body.

[0083] (5) After the cemented carbide green body treated in step (4) was dried in a drying furnace at 55°C for 8 hours, the green body was placed in hydrogen, heated to 550°C at a heating rate of 1°C / min and kept warm for 1 hour, heated to 1050°C at a heating rate of 5°C / min under vacuum conditions, and finally heated to 1400°C at a heating rate of 10°C / min in an argon atmosphere and kept warm for 45 minutes.

[0084] The printing feed prepared using these parameters exhibits the shear-thinning characteristics of a pseudoplastic fluid, resulting in excellent printability. By properly matching printing parameters with hot isostatic pressing (HIP), the wedge-shaped or diamond-shaped pores in the cemented carbide green body are effectively reduced, achieving a relative density of 99.1%. After debinding and sintering, the relative density of the sintered sample reaches 99.4%. Furthermore, the dimensional shrinkage of the sintered sample in the X, Y, and Z directions is 17.64%, 17.37%, and 18.12%, respectively.

[0085] Embodiment 5:

[0086] (1) Prepare WC-Co cemented carbide powder by ball mill, particle size D 50 0.5-10μm, composed of 94wt.% WC and 6wt.% Co, 1.8kg is measured for standby use; at room temperature, 8cm 3 Stearic acid, 8cm 3 Polyethylene, 8cm 3 Polypropylene, 8cm 3 Polymethyl methacrylate, 8cm 3 Polystyrene, 40cm 3 Wax is ready for use. Heat the internal mixer to 130℃ and mix 8cm 3 Stearic acid, 8cm 3 Polyethylene, 8cm 3 Polypropylene, 8cm 3 Polymethyl methacrylate, 8cm 3 Polystyrene, 40cm 3 Paraffin was prepared and 1.8 kg of WC-Co powder was added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 170°C, rotation speed of 60 rpm, and stirring time of 100 min to prepare a WC-Co internal mixing mixture with a powder loading of 60 vol.%.

[0087] The obtained banburying mixture was placed in a granulator, and the screw speed was set to 60 rpm, the pressure was 10 kg, and the temperature was 140° C. to obtain granular printing feed with a particle size of about 2-3.5 mm.

[0088] (2) Using the granular printing feed obtained in step (1) as raw material, a fused deposition modeling device is used to form a cemented carbide green body through 3D printing technology. The parameters are set as follows: nozzle diameter is 0.4 mm, nozzle temperature is 170°C, layer thickness is 0.1 mm, printing speed is 30 mm / s, microfilament overlap ratio is 5%, extrusion flow rate is 75%, filling rate is 70%, and [45°, 45°] is used as the 3D printing routing method.

[0089] (3) The cemented carbide green body printed in step (2) is subjected to hot isostatic pressing. The cemented carbide green body prepared in step (3) is placed in a hot isostatic press. Under an inert atmosphere, the hot isostatic press is heated to 150°C for heat preservation. Subsequently, the press is pressurized to 5MPa, 20MPa, and 25MPa at a pressure increase rate of 1MPa / min, 2MPa / min, and 5MPa / min, respectively. The pressure is maintained at 25MPa for 60min, and the hot isostatic press is cooled to room temperature. Subsequently, the pressure is reduced to 20MPa, 10MPa, and 5MPa at a pressure reduction rate of 5MPa / min, 2MPa / min, and 1MPa / min. When the pressure drops to 5MPa, the press is unloaded to normal pressure.

[0090] (4) The cemented carbide green body treated in step (3) is immersed in n-heptane liquid and sealed, and then the n-heptane solution is heated to 35° C. in a water bath and kept warm for about 16 hours to remove the binder in the cemented carbide green body.

[0091] (5) After the cemented carbide green body treated in step (4) was dried in a drying furnace at 55°C for 8 hours, the green body was placed in hydrogen and heated to 600°C at a heating rate of 1°C / min and kept warm for 1 hour. The temperature was then raised to 1050°C at a heating rate of 5°C / min under vacuum conditions. Finally, the temperature was raised to 1430°C at a heating rate of 10°C / min in an argon atmosphere and kept warm for 45 minutes.

[0092] The printing feed prepared using these parameters exhibits the shear-thinning characteristics of a pseudoplastic fluid, resulting in excellent printability. By properly matching printing parameters with hot isostatic pressing (HIP), the wedge-shaped or diamond-shaped pores in the cemented carbide green body are effectively reduced, achieving a relative density of 98.5%. After debinding and sintering, the relative density of the sintered sample reaches 99.3%. Furthermore, the dimensional shrinkage of the sintered sample in the X, Y, and Z directions is 17.57%, 17.61%, and 18.44%, respectively.

[0093] Comparative Example 1:

[0094] The difference from step (2) described in Example 1 is that in Comparative Example 1, the 3D printing parameters in step (2) described in Example 1 are changed for printing, and the 3D printing parameters are modified as follows: nozzle diameter is 0.6 mm, nozzle temperature is 150°C, layer thickness is 0.5 mm, microfilament overlap ratio is 0%, printing speed is 80 mm / s, extrusion flow rate is 100%, filling rate is 100%, and routing mode is [0,90°].

[0095] The difference from step (3) described in Example 1 is that in Comparative Example 1, step (3) described in Example 1 is cancelled, that is, the cemented carbide green body prepared in step (2) described in Example 1 is directly processed in steps (4) and (5) described in Example 1 to prepare a cemented carbide sintered sample.

[0096] Other operation steps are consistent with those in Example 1.

[0097] After 3D printing using this parameter, due to the excessive printing speed, high layer thickness, and failure to set the microfilament overlap ratio, the feed extruded from the nozzle cannot fill the matrix well. Microscopic observation shows that obvious stacked wedge-shaped holes or diamond-shaped pores appear in the prepared cemented carbide green body. The relative density of the cemented carbide sintered sample after degreasing and sintering is low, only 94.4%, and the sample exhibits uneven dimensional shrinkage, with dimensional shrinkage rates of 20.04%, 20.98% and 24.35% in the X, Y and Z directions, respectively.

[0098] Comparative Example 2:

[0099] The difference from step (2) described in Example 1 is that in Comparative Example 1, the 3D printing parameters in step (2) described in Example 1 are changed for printing, and the 3D printing parameters are modified as follows: nozzle diameter is 0.6 mm, nozzle temperature is 150°C, layer thickness is 0.4 mm, microfilament overlap ratio is 0%, printing speed is 80 mm / s, extrusion flow rate is 100%, filling rate is 60%, and routing mode is [0,90°].

[0100] The difference from step (3) described in Example 1 is that the cemented carbide green body prepared in step (2) is placed in a hot isostatic press, and the hot isostatic press is heated to 250°C under an inert atmosphere for insulation, and then pressurized to 10MPa, 30MPa, and 100MPa at a pressure increase rate of 1MPa / min, 2MPa / min, and 5MPa / min, respectively, and maintained at 100MPa for 60min, and the hot isostatic press is cooled to room temperature, and then the pressure is reduced to 30MPa, 10MPa, and 5MPa at a pressure reduction rate of 5MPa / min, 2MPa / min, and 1MPa / min, and unloaded to normal pressure when the pressure drops to 5MPa.

[0101] Other operation steps are consistent with those in Example 1.

[0102] After 3D printing using this parameter, the feed extruded from the nozzle cannot fill the matrix well due to the high layer thickness. Due to the high hot isostatic pressing temperature, the binder is partially decomposed, which reduces the effect of hot isostatic pressing on densification of the green body. The relative density of the cemented carbide sintered sample after degreasing and sintering is low, only 98.5%, and the sample shows obvious uneven dimensional shrinkage, with dimensional shrinkage rates of 19.79%, 19.88% and 22.73% in the X, Y and Z directions, respectively.

[0103] Comparative Example 3:

[0104] The difference from step (2) described in Example 1 is that in Comparative Example 1, the 3D printing parameters in step (2) described in Example 1 are changed for printing, and the 3D printing parameters are modified as follows: nozzle diameter is 0.6 mm, nozzle temperature is 150°C, layer thickness is 0.3 mm, microfilament overlap ratio is 0%, printing speed is 80 mm / s, extrusion flow rate is 100%, filling rate is 60%, and routing mode is [0,90°].

[0105] The difference from step (3) described in Example 1 is that the cemented carbide green body prepared in step (2) is placed in a hot isostatic press, and the hot isostatic press is heated to 50°C under an inert atmosphere for insulation, and then pressurized to 10MPa, 30MPa, and 50MPa at a pressure increase rate of 1MPa / min, 2MPa / min, and 5MPa / min, respectively, and maintained at 50MPa for 60min, and the hot isostatic press is cooled to room temperature, and then the pressure is reduced to 30MPa, 10MPa, and 5MPa at a pressure reduction rate of 5MPa / min, 2MPa / min, and 1MPa / min, and unloaded to normal pressure when the pressure drops to 5MPa.

[0106] Other operation steps are consistent with those in Example 1.

[0107] After 3D printing using this parameter, due to the high layer thickness, the feed extruded from the nozzle cannot fill the matrix well. Due to the low hot isostatic pressing temperature, some polymer components in the binder are still in solid state, and the effect of hot isostatic pressing on densification of the green body is not obvious. The relative density of the cemented carbide sintered sample after degreasing and sintering is low, only 97.5%, and the sample shows obvious uneven dimensional shrinkage, with dimensional shrinkage rates of 19.85%, 19.94% and 23.43% in the X, Y and Z directions, respectively.

[0108] Comparative Example 4:

[0109] The difference from step (2) described in Example 1 is that in Comparative Example 1, the 3D printing parameters in step (2) described in Example 1 are changed for printing, and the 3D printing parameters are modified as follows: nozzle diameter is 0.6 mm, nozzle temperature is 150°C, layer thickness is 0.4 mm, microfilament overlap ratio is 0%, printing speed is 80 mm / s, extrusion flow rate is 100%, filling rate is 60%, and routing mode is [0,90°].

[0110] The difference from step (3) described in Example 1 is that the cemented carbide green body prepared in step (2) is placed in a hot isostatic press, and the hot isostatic press is heated to 400°C under an inert atmosphere for insulation, and then pressurized to 10MPa, 30MPa, and 100MPa at a pressure increase rate of 1MPa / min, 2MPa / min, and 5MPa / min, respectively, and maintained at 100MPa for 60min, and the hot isostatic press is cooled to room temperature, and then the pressure is reduced to 30MPa, 10MPa, and 5MPa at a pressure reduction rate of 5MPa / min, 2MPa / min, and 1MPa / min, and unloaded to normal pressure when the pressure drops to 5MPa.

[0111] Other operation steps are consistent with those in Example 1.

[0112] After 3D printing using this parameter, the hot isostatic pressing temperature is high, and the binder decomposes significantly. During the process of venting the gas generated by the large amount of pyrolyzed binder inside the printed green body, cross-linked pores are easily formed inside the printed green body. The pores are thermally expanded by high temperatures, generating high internal compressive stress, which causes defects such as bubbles and cracks in the printed green body, and changes in the dimensional accuracy of the printed green body. After degreasing and sintering, the relative density of the cemented carbide sintered sample is 96.7%, but the shape of the sample has changed significantly, and the shrinkage rate of the various dimensions is difficult to measure. Comparative Example 5:

[0113] The difference from step (1) of Example 1 is that in Comparative Example 2, the internal mixer is heated to 130°C, and the 6.4 cm 3 Stearic acid, 6.4 cm 3 Polyethylene, 6.4cm 3 Polypropylene, 6.4cm 3 Polymethyl methacrylate, 6.4cm 3 Polystyrene, 32cm 3 Paraffin was prepared and 1.92 kg of WC-Co powder was added into the mixing chamber of the internal mixer. The specific parameters were designed as follows: mixing temperature of 170°C, rotation speed of 60 rpm, and stirring time of 100 min. A WC-Co internal mixing mixture with a powder loading of about 66 vol.% was prepared.

[0114] Other operation steps are consistent with those in Example 1.

[0115] Because the powder loading in the feed prepared by this method is too large, the feed viscosity increases significantly, and due to the limited pressure of the screw extruder in the molten deposition equipment, the feed extrusion is not smooth, the nozzle is blocked, and the feed stacking and deposition are not connected during the process of forming cemented carbide green billets using 3D printing technology, which makes the parts unable to be formed normally.

[0116] Obviously, the above embodiments and comparative examples are merely examples for clarity of explanation and are not intended to limit the embodiments. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for manufacturing cemented carbide with uniform shrinkage in all directions, characterized in that The method comprises the following steps: first, preparing a printing feed with a high powder loading; Second, the green body is prepared by fused deposition modeling (FDM) printing. Third, the green body is subjected to low-temperature hot isostatic pressing to obtain a green body with high relative density and precise dimensions. Finally, the green body is degreased and sintered to obtain a cemented carbide product with high relative density and uniform dimensional shrinkage in all directions. During low temperature hot isostatic pressing treatment, the temperature is controlled at 50-200℃; The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions comprises the following steps: (1) Mixing and preparing printing feed: The WC-Co powder A and the binder B are mixed according to the designed ratio, and the mixture is put into a banbury mixer for banbury mixing to prepare a banbury mixture C in which the WC-Co powder and the binder B are uniformly banbury mixed. The prepared banburying mixture C is fed into a granulator to prepare a granular printing feed D with uniform size and a particle size of 1-4 mm; The adhesive B comprises a backbone component, a plasticizing component, and a dispersing component; the backbone component is at least one of polyethylene, polypropylene, ethylene-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, and polyacetal; the plasticizing component comprises at least one of paraffin wax, microcrystalline wax, beeswax, and palm wax; and the dispersing component is at least one of stearic acid and stearates; wherein the volume proportion of the plasticizing component in the adhesive B is 35-65%, the volume proportion of the backbone component is 30-50%, and the volume proportion of the dispersing component is 1-15%; The particle size D of the WC-Co powder A in step (1) 50 Less than 20μm; the volume proportion of WC-Co powder A in the internal mixing mixture C is 45-65%, and the volume proportion of binder B is 35-55%; Step (1) The parameters of the internal mixer are set as follows: mixing temperature is 120-200°C, speed is 30-90 rpm, and stirring time is greater than 30 min; The preparation parameters of the printing feed D in step (1) are set as follows: screw speed 30-80 rpm, screw pressure 3-10 kg, and particle diameter 1-4 mm; (2) FDM printing to prepare green parts: The granular printing feed D obtained in step (1) is used as a raw material to prepare a cemented carbide green body E by FDM printing; the cemented carbide green body E described in step (2) is prepared by using the granular printing feed D prepared in step (1) as a raw material and adopting FDM equipment printing technology; the printing process is as follows: a three-dimensional CAD model is established on a computer according to the shape of the part; the model is sliced ​​and layered using software and imported into an additive manufacturing system; the granular printing feed D is heated by a numerical control system, and the granular material is extruded by a screw and formed layer by layer according to the slicing route until the printed green body E is obtained; The printing process parameters are as follows: nozzle diameter 0.2-0.8 mm, nozzle temperature 120-200°C, layer thickness 0.1-0.8 mm, printing speed 25-50 mm / s, filling rate 50-130%, microfilament overlap ratio 1-60%, filling mode of [0, 90°], [45°, -45°], or a combination of the two filling modes; (3) Hot isostatic pressing: The green body E prepared in step (2) is subjected to low-temperature hot isostatic pressing in an inert atmosphere to obtain a cemented carbide green body F with high relative density and good dimensional accuracy; in the hot isostatic pressing process of step (3), the pressure is increased at different rates to reach the corresponding pressure ranges of 5-10MPa, 10-40MPa, and 40-100MPa, and the corresponding pressure increase rates are 1-5MPa / min, 1-5MPa / min, and 1-10MPa / min; in an inert atmosphere, the hot isostatic press is cooled to room temperature, and the pressure is reduced from the maximum pressure to the corresponding pressure ranges of 40-60MPa, 20-40MPa, and 5-20MPa at different pressure reduction rates, and the corresponding pressure reduction rates are 1-10MPa / min, 1-5MPa / min, and 1-5MPa / min, and finally the pressure is naturally reduced from 10MPa or 5MPa to normal pressure; (4) Solvent degreasing of green body: first, n-heptane is heated to a set temperature, and then the cemented carbide green body F treated in step (3) is immersed in the heated n-heptane for degreasing, and then taken out and vacuum dried to obtain a solvent degreased green body G; The soaking and degreasing time is determined according to the size of the green body; the drying temperature and time are determined according to the characteristic temperatures of the adhesive and n-heptane; (5) Thermal debinding and sintering: The green body G prepared in step (4) is thermally debinded and sintered to obtain a WC-Co cemented carbide solid part H.

2. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 1, characterized in that: The microfilament overlap ratio in step (2) is 1-40%.

3. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 2, characterized in that: The microfilament overlap ratio in step (2) is 4-35%.

4. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 2, characterized in that: In the low-temperature hot isostatic pressing process of step (3), the parameters are set as follows: in an inert atmosphere, the hot isostatic press is heated to 50-200°C and kept warm.

5. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 4, characterized in that: The gas of the inert atmosphere is helium, argon, or a mixture of argon and helium, with a purity of 99.99 wt %, wherein the oxygen content is less than 0.0001 wt %.

6. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 1, characterized in that: In the solvent degreasing process of step (4), the cemented carbide green body F treated in step (3) is immersed in n-heptane for 4-30 hours; after the immersion is completed, the cemented carbide green body F is taken out and placed in a drying furnace for drying at a temperature of 40-80°C to obtain a solvent degreased green body G; the parameter ranges are: the holding temperature of n-heptane is 15-80°C; the immersion time is 4-30 hours; the drying temperature is 40-80°C; and the drying time is 3-14 hours.

7. A method for additively manufacturing cemented carbide with uniform shrinkage in all directions according to any one of claims 1 to 6, characterized in that: After the soaking is completed, the cemented carbide green body F is taken out and placed in a drying furnace for drying at a temperature of 40-80°C to obtain a solvent-degreased green body G; the parameter range is: the holding temperature of n-heptane is 20-60°C; the soaking time is 8-20 hours; the drying temperature is 40-60°C; and the drying time is 6-8 hours.

8. The method for manufacturing cemented carbide additive materials with uniform shrinkage in all directions according to claim 1, characterized in that: In the step (5), the thermal debinding-sintering is divided into two stages, wherein the first stage is a medium-low temperature thermal debinding stage with a temperature range of 400-750°C; in the first stage, a reducing atmosphere is used and the temperature is heated from room temperature to a first temperature at a heating rate of 0.1-8°C / min; the second stage is a high-temperature sintering and heat preservation stage with a temperature range of 750-1500°C; in the second stage, a vacuum atmosphere is used and the temperature is heated from a temperature greater than the first temperature to a second temperature at a heating rate of 0.5-20°C / min.

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