A cemented carbide and its additive manufacturing method

Abstract

This invention provides a cemented carbide and its additive manufacturing method, belonging to the field of additive manufacturing. The method uses cemented carbide powder as raw material and employs photopolymerization for additive manufacturing. First, the surface of the cemented carbide powder is modified using an organic coating method, enabling a cemented carbide powder slurry composed of surface-modified cemented carbide powder, photosensitive resin, dispersant, and carburizer to undergo a photopolymerization reaction. Then, photocuring and additive manufacturing are performed, followed by debinding, sintering, or hot isostatic pressing for densification to obtain cemented carbide parts with complex three-dimensional structures. Compared with high-energy beam laser selective melting (SLM), this invention avoids problems such as carbon loss and binder volatilization caused by direct contact between the high-energy beam and the cemented carbide. Compared with binder jetting additive manufacturing (BJP), the method of this invention is simpler, has fewer steps, produces more precise parts, and has superior surface quality.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing, and in particular to a cemented carbide and its additive manufacturing method. Background Technology

[0002] Traditionally, cemented carbide is mainly produced industrially using powder metallurgy. This involves mixing and grinding raw material powders, pressing them into blanks, removing the binder, and sintering to densify the material into cemented carbide components. Finally, depending on the product's shape and precision requirements, the sintered body is ground, etched, or polished to obtain the finished cemented carbide product. However, this method is only suitable for producing products with relatively simple shapes and structures, and it is increasingly difficult to meet the industrial demand for complex, irregularly shaped cemented carbide products.

[0003] Currently, the main additive manufacturing technologies used for cemented carbide include selective laser sintering, selective laser melting, fused deposition modeling, direct writing, and binder spraying. Depending on whether the formed product requires subsequent high-temperature sintering, these methods can be divided into direct additive manufacturing of cemented carbide and indirect additive manufacturing. Direct additive manufacturing of cemented carbide utilizes a high-energy heat source to directly melt or sinter the cemented carbide powder on the powder bed, causing it to remelt and solidify or sinter onto a printing platform to obtain complex structural parts. Compared to other additive manufacturing technologies, due to the use of micro-melt pools for layer-by-layer deposition, small melting volume, and fast solidification speed, the formed samples have advantages such as fine microstructure, excellent mechanical properties, and fewer post-processing steps. Meanwhile, due to its high cooling rate, high-energy heat source, and localized liquid-phase sintering characteristics, it suffers from defects such as delamination caused by abnormal grain growth, formation of carbon-deficient phases (η phase, Co3W3C, Co2W4C, or Co3W6C) due to cobalt and graphite evaporation, porosity caused by the inability of graphite phase gas to escape due to the high cooling rate, spatter caused by high-energy laser bombardment of the surface, and cracks caused by large residual stress. Compared with direct additive manufacturing methods, cemented carbide prepared by indirect additive manufacturing methods has a uniform microstructure, no abnormal grain growth or delamination, and a lower manufacturing cost. However, existing indirect additive manufacturing cemented carbide technologies still have many problems, such as insufficient interlayer bonding force of the blank, low strength and density, large surface roughness of the product, and difficulty in preparing particularly complex shaped parts.

[0004] Hard alloy powders, whether elemental carbide powders such as WC, TiC, and TiNC, or composite powders such as WC-Co, WC-TiC, WC-TiC-TaC, TiCN-WC-Mo2C-Ni-Co, and WC-TiC-Tac-TiCN-Co, are all dark-colored powders with high light absorption rates. This prevents the photosensitive resin in the hard alloy powder slurry from being photo-initiated to polymerize, thus hindering photopolymerization and photocuring additive manufacturing. Furthermore, the high density of hard alloy powders (e.g., the density of WC powder is 15.63 g / cm³) further complicates the process. 3 This makes cemented carbide powder slurry extremely unstable and prone to sedimentation. This makes it difficult to use photopolymer additive manufacturing to manufacture cemented carbide parts.

[0005] Therefore, there is an urgent need to develop a cemented carbide and its additive manufacturing method. Summary of the Invention

[0006] This invention provides a cemented carbide and its additive manufacturing method, which aims to solve the problems of photocuring and sedimentation instability of cemented carbide powder slurry.

[0007] To achieve the above objectives, embodiments of the present invention provide a cemented carbide and its additive manufacturing method. This method uses cemented carbide powder as raw material and employs photopolymerization for additive manufacturing of cemented carbide. Specifically, it uses an organic coating method to modify the surface of the cemented carbide powder, enabling the cemented carbide powder slurry composed of photosensitive resin, cemented carbide powder, and dispersant to undergo a photopolymerization reaction. Subsequently, it uses photopolymerization-based additive manufacturing technology for photocuring additive manufacturing and molding, and then performs debinding, sintering, or hot isostatic pressing densification to obtain a cemented carbide part with a three-dimensional complex structure, thereby solving the problems of photocuring and sedimentation instability of cemented carbide powder slurry.

[0008] This invention provides an additive manufacturing method for cemented carbide, comprising the following steps:

[0009] S1: Screening of cemented carbide powders and surface modification using organic coating methods to obtain surface-modified cemented carbide powders; to obtain cemented carbide powder photosensitive slurry with stable rheological properties, the powder particle size D is screened according to the requirements of photosensitive slurry viscosity, powder density, and alloy composition. 50 The range is 20–5000 nm;

[0010] S2: The surface-modified cemented carbide powder, photosensitive resin monomer, photoinitiator, dispersant and carbon raiser are ball-milled and mixed to obtain a photosensitive slurry with suitable viscosity and solid content;

[0011] S3: The photosensitive paste is degassed and then transferred to a photopolymerization additive manufacturing equipment for additive manufacturing to obtain a cemented carbide blank;

[0012] S4: The cemented carbide billet is placed in a furnace for degreasing, conversion, and sintering to obtain cemented carbide. Degreasing and conversion are performed to remove organic components from the billet or to convert some organic matter into carbon.

[0013] In one aspect of this invention, the surface modification method is solution polymerization, specifically: adding cemented carbide powder and an organic-ethanol aqueous solution to a reaction vessel, adding an initiator while stirring, heating to carry out the reaction, filtering, and drying to obtain surface-modified cemented carbide powder.

[0014] In one aspect of this invention, the cemented carbide powder is at least one of the following: elemental carbide powder, alloy powder of elemental carbide powder and binder, solid solution powder of carbide, and alloy powder of solid solution powder of carbide and binder; the elemental carbide powder is at least one of WC, TiC, and TiNC; the solid solution powder is at least one of WC-TiC, WC-TiC-TaC, and WC-TiC-TaC-NbC; the binder is Co, Ni, or Fe; the organic compound is one or more of butyl acrylate, acrylamide, methyl methacrylate, and pyrrole, with a mass concentration of 1% to 50% of the organic compound-ethanol aqueous solution; initiator The reagent is one or more of ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, azobisisobutyronitrile, azobisisobutyramidine hydrochloride, potassium persulfate, and dicumyl peroxide, with a mass concentration of 0.001% to 10% of the organic-ethanol aqueous solution; the volume ratio of cemented carbide powder to the organic-ethanol aqueous solution is 0.01 to 0.6; the mass concentration of the ethanol aqueous solution in the organic-ethanol aqueous solution is 50% to 99%; the mass concentration of ethanol in the ethanol aqueous solution is 20% to 90%; the heating temperature is 10 to 80℃; the reaction time is 0.1 h to 24 h; the stirring rate is 10 to 600 rad / min; and the drying temperature is 50℃ to 180℃. Drying is performed using conventional oven drying, vacuum drying, or spray drying. More preferably, the cemented carbide powder is at least one of WC+Co, WC+Ni, WC+Co / Ni, WC+Fe / Co / Ni, WC-TiC+Co, WC-TiC+Ni, WC-TiC+Co / Ni, WC-TiC+Fe / Co / Ni, WC-TiC-TaC+Co, WC-TiC-TaC+Ni, WC-TiC-TaC+Co / Ni, WC-TiC-TaC+Fe / Co / Ni, WC-TiC-TaC-NbC+Co, WC-TiC-TaC-NbC+Ni, WC-TiC-TaC-NbC+Co / Ni, and WC-TiC-TaC-NbC+Fe / Co / Ni, but is not limited thereto.

[0015] In one aspect of this invention, the photosensitive resin monomer is one or more selected from hydroxyethyl acrylate (HEA), pentaerythritol tetraacrylate (PET4A), pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), tripropylene glycol diacrylate (TPGDA), 1,6-hexanediol diacrylate (HDDA), dipropylene glycol diacrylate (DPGDA), and dipentaerythritol hexaacrylate (DPHA); the photoinitiator is phenylbis(2,4,6-trimethylbenzoyl) One or more of the following photoinitiators are used: phosphine oxide (photoinitiator 819), 1-hydroxycyclohexylphenyl ketone (photoinitiator 184), trimethylbenzoyl-diphenylphosphine oxide (photoinitiator TPO), and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone (photoinitiator 369); the dispersant is XYS-2800 (modified polymer solution), XYS-5800 (modified polymer solution), BYK-164 (DISPERBYK-164, modified polyurethane solution), or DEGO655 (TEGO). The additives are one or more of the following: DISPER 655 modified polyether, KD-2 (Croda, Hypermer KD-2), KH560 (γ-glycidyl etheroxypropyltrimethoxysilane), KH550 (3-aminopropyltriethoxysilane), SP-710 (block copolymer containing acidic groups), and KOS-110 (polymer containing acidic groups); the carbon raiser is one or more of phenolic resin, carbon black, and asphalt.

[0016] In one aspect of this invention, the volume solids content of the photosensitive resin monomer is 10%–90%; the volume solids content of the surface-modified cemented carbide powder is 10%–90%; the amount of photoinitiator added is 1%–10% of the mass of the photosensitive resin monomer; the amount of dispersant added is 0.1%–10% of the mass of the surface-modified cemented carbide powder; the amount of carbon raiser added is 1%–10% of the mass of the modified cemented carbide powder; the ball-to-material ratio of the ball mill is 0–1 / 2, the milling speed is 10–2000 rad / min, and the time is 1–24 h.

[0017] In one aspect of this invention, the degassing method is: centrifugal degassing, with a degassing time of 1 min to 2 min; or vacuum degassing, with a degassing time of 10 min to 60 min; the photopolymer additive manufacturing equipment is a stereolithography (SLA) or digital light processing (DLP) equipment, or other photopolymer additive manufacturing equipment.

[0018] In one aspect of this invention, the degreasing atmosphere is hydrogen, vacuum, or an inert gas; the degreasing process is as follows: heating from room temperature to 300-400°C and holding for 1-60 minutes, then heating to 400-500°C and holding for 1-60 minutes, then heating to 500-600°C and holding for 1-60 minutes, then heating to 800-1000°C and holding for 10-120 minutes, with a heating rate of 0.01-30°C / min.

[0019] In one aspect of this invention, the sintering atmosphere is vacuum, nitrogen, or argon; the sintering process is as follows: under vacuum, the temperature is raised to 1000–1200°C and held for 1–60 min, then raised to 1250–1500°C and held for 60–240 min under an inert gas pressure of 0–10 MPa, and finally cooled to 80°C within 200–300 min, with a heating rate of 0.01–30°C / min.

[0020] In one aspect of the present invention, the sintered cemented carbide is densified by hot isostatic pressing; the hot isostatic pressing temperature is 1300-2000℃, the time is 30-120 min, and the pressure is 10-100 MPa.

[0021] Based on a general inventive concept, the present invention also provides a cemented carbide obtained by the above-described additive manufacturing method.

[0022] The above-described solution of the present invention has the following beneficial effects:

[0023] (1) The present invention solves the problems of photocuring and sedimentation instability of cemented carbide powder slurry by means of screening the particle size of cemented carbide powder, surface modification of cemented carbide powder by coating with organic matter and adapting the resin system.

[0024] (2) Compared with other methods for surface modification of cemented carbide powder, this invention uses a simple organic material to coat the powder. After coating, only drying is required, without the need for subsequent high-temperature treatment processes such as atmospheric calcination or reduction. The operation is simpler and the cost is lower. In addition, because cemented carbide powder has a high density, much higher than the coated organic material, and is difficult to suspend in the polymerization reaction solution during the synthesis and coating process, it is usually difficult to detect that organic materials with a large density difference can be coated on the surface of cemented carbide powder through powder particle size screening process control.

[0025] (3) The present invention adopts cemented carbide indirect additive manufacturing technology. Compared with cemented carbide direct additive manufacturing technology such as SLM and cemented carbide additive manufacturing technology such as BJP, the cemented carbide powder used in the present invention does not need to be spherical and has no special performance requirements. The cemented carbide powder prepared by traditional powder metallurgy can be used, which greatly reduces the manufacturing cost of cemented carbide additive manufacturing. It also avoids the direct contact between high energy beam and hard phase powder such as WC, which greatly avoids the WC carbon loss and Co volatilization problems that are difficult to avoid in cemented carbide direct additive manufacturing technology.

[0026] (4) The present invention uses light irradiation forming, which results in sufficient interlayer bonding force of the blank, higher precision and strength of the formed parts, and the density of cemented carbide can reach 100%. It can also prepare cemented carbide parts with more complex shapes and better surface quality. Moreover, the process route of the present invention is very close to the traditional powder metallurgy process route for preparing cemented carbide, which is easy to be accepted and promoted.

[0027] (5) The present invention has wide applicability and can be used for additive manufacturing of cemented carbides of various materials, such as cobalt-based cemented carbides, nickel-based cemented carbides, binderless cemented carbides, TiNC series cemented carbides and steel-bonded cemented carbides. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The images show the additive manufacturing of YG6 cemented carbide billet (left) and hot isostatic pressing state (right) in Embodiment 1 of the present invention.

[0030] Figure 2 This is an additive manufacturing of a cemented carbide nozzle blank according to Embodiment 2 of the present invention;

[0031] Figure 3 It is the hot isostatic pressed hard alloy WC-9Ni of Embodiment 3 of the present invention;

[0032] Figure 4 This is a steel-structured cemented carbide component manufactured by additive manufacturing according to Embodiment 5 of the present invention. Detailed Implementation

[0033] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0034] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0036] This invention addresses existing problems by providing a cemented carbide and its additive manufacturing method.

[0037] Example 1

[0038] The steps for additive manufacturing WC-6Co cemented carbide YG6 are as follows:

[0039] S1: Mix 780 parts WC powder (D) 50 50 parts of Co powder (1000 nm) were added to a three-necked flask containing 156 parts of butyl acrylate and 2340 parts of ethanol solution (ethanol concentration of 60%). Then, 1.15 parts of azobisisobutyronitrile (AIB) were added under stirring at 80 rad / min. The mixture was then heated to 70 °C and reacted for 6 h. The powder was filtered out and washed three times with anhydrous ethanol. The powder was then dried in a vacuum drying oven at 80 °C for 12 h to obtain surface-modified WC-6Co cemented carbide powder.

[0040] S2: 400 parts of modified WC-6Co cemented carbide powder, 20 parts of HDDA, 80 parts of TMPTA, 1 part of TPO, 3 parts of dispersant DEGO655, and 1.2 parts of carbon raiser phenolic resin were added to a ball mill jar and mixed by ball milling at a rate of 200 rad / min to obtain WC-6Co cemented carbide slurry. The grinding balls were cemented carbide balls, with a ball-to-material ratio of 1 / 3; the ball milling time was 2 hours.

[0041] S3: After centrifuging and degassing the cemented carbide slurry for 2 minutes, place it in the material container of a DLP additive manufacturing equipment based on photopolymerization, and then perform additive manufacturing to obtain a YG6 cemented carbide preform (e.g., Figure 1 (As shown).

[0042] S4: The cemented carbide YG6 billet is placed in the furnace for degreasing, conversion, and sintering. The degreasing atmosphere is hydrogen, vacuum, or an inert gas atmosphere. The degreasing process is as follows: under a hydrogen atmosphere (hydrogen flow rate of 300 mL / min), the temperature is raised from room temperature to 350℃ and held for 30 min, then raised to 450℃ and held for 30 min; under an argon atmosphere (argon flow rate of 1600 mL / min), the temperature is further raised to 550℃ and held for 30 min; then raised to 1000℃ and held for 60 min; under an argon atmosphere and an inert gas pressure of 5 MPa, the temperature is raised to 1420℃ and held for 60 min; finally, under an argon atmosphere, the temperature is lowered to 80℃ within 300 min to obtain the cemented carbide YG6 sintered body. The performance indicators of the YG6 sintered body are listed in Table 1 below. Subsequently, the cemented carbide YG6 sintered body was placed in a hot isostatic pressing furnace, heated to 1450℃ at a rate of 15℃ / min, and held at 80MPa for 60min. After hot isostatic pressing, the relative density of the cemented carbide increased to 99.3%. Figure 1 The image shows the additively manufactured YG6 cemented carbide billet and its hot isostatic pressing state.

[0043] Table 1. Performance indicators of YG6 sintered body

[0044]

[0045] Comparative Example 1

[0046] Compared with Example 1, Comparative Example 1 used WC powder with a particle size of 6000 nm, and everything else was exactly the same. After performing steps S1 and S2, the resulting slurry settled too quickly to complete step S3.

[0047] Example 2

[0048] The steps for additive manufacturing of a binderless cemented carbide nozzle are as follows:

[0049] S1: Mix 200 parts WC powder (D) 50 The powder (800 nm) was added to a three-necked flask containing 30 parts butyl acrylate and 600 parts ethanol solution (ethanol concentration 80%). Then, 0.3 parts azobisisobutyronitrile (AIOBR) was added under stirring at 260 rad / min. The mixture was then heated to 75 °C and reacted for 6 h. The powder was filtered out and washed three times with anhydrous ethanol. The powder was then dried in an oven at 120 °C for 8 h to obtain surface-modified WC cemented carbide powder.

[0050] S2: 800 parts of modified WC cemented carbide powder, 50 parts of HDDA, 50 parts of HEA, 2 parts of initiator 369, and 6 parts of dispersant KOS-110 were added to a ball mill jar and mixed by ball milling at a rate of 400 rad / min to obtain a binder-free WC cemented carbide slurry. The grinding balls were cemented carbide balls, with a ball-to-material ratio of 1 / 3; the ball milling time was 1 hour.

[0051] S3: After centrifuging and degassing the cemented carbide slurry for 2 minutes, place it in the material container of a photopolymerization-based additive manufacturing (SLA) device, and then perform additive manufacturing to obtain a binderless WC cemented carbide nozzle preform (e.g., Figure 2 (As shown).

[0052] S4: The cemented carbide nozzle blank is placed in the furnace for degreasing, conversion, and sintering. The degreasing atmosphere is hydrogen, vacuum, or an inert gas atmosphere. The degreasing process is as follows: under a hydrogen atmosphere (hydrogen flow rate of 500 mL / min), the temperature is raised from room temperature to 330℃ and held for 40 min, then raised to 480℃ and held for 30 min; under an argon atmosphere (argon flow rate of 1200 mL / min), the temperature is raised to 580℃ and held for 30 min; then raised to 1100℃ and held for 60 min; under an argon atmosphere and an inert gas pressure of 5 MPa, the temperature is raised to 1480℃ and held for 60 min; finally, under an argon atmosphere, the temperature is lowered to 80℃ within 600 min to obtain the cemented carbide sintered body. Subsequently, the cemented carbide sintered body is placed in a hot isostatic pressing furnace, heated to 1850℃ at a rate of 10℃ / min, and held at a pressure of 100 MPa for 80 min. The relative density of cemented carbide increases to 98.9% after hot isostatic pressing.

[0053] Comparative Example 2

[0054] Compared with Example 2, Comparative Example 2 used WC powder with a particle size of 15 nm, and was otherwise identical. After step S1, the addition of WC powder completely caused it to lose its fluidity, making it impossible to complete step S2.

[0055] Example 3

[0056] The steps for additive manufacturing of WC-9Ni cemented carbide are as follows:

[0057] S1: Mix 200 parts WC powder (D) 5018 parts of Ni powder (2000 nm) were added to a three-necked flask containing 35 parts of acrylamide and 600 parts of ethanol solution (ethanol concentration of 90%). Then, 2.6 parts (6.67% of the monomer) of ammonium persulfate were added under a stirring rate of 100 rad / min. The mixture was then heated to 60 °C and reacted for 6 h. The powder was filtered out and washed three times with anhydrous ethanol. The powder was then dried in a vacuum drying oven at 80 °C for 12 h to obtain surface-modified WC-9Ni cemented carbide powder.

[0058] S2: Add 800 parts of modified WC-9Ni cemented carbide powder (ZN108), 30 parts of TPGDA, 70 parts of HEA, 2 parts of 819, 6 parts of dispersant KH-560 and 2 parts of carbon black powder to a ball mill jar and ball mill at a rate of 1000 rad / min for 0.5 h to obtain WC-9Ni cemented carbide slurry.

[0059] S3: After vacuum degassing and degassing the cemented carbide slurry for 20 minutes, place it in the material container of a DLP additive manufacturing equipment based on photopolymerization, and then perform additive manufacturing to obtain a WC-9Ni cemented carbide (ZN108) preform (e.g. Figure 3 (As shown).

[0060] S4: The cemented carbide billet is placed in a furnace for degreasing, conversion, and sintering. The degreasing atmosphere is hydrogen, vacuum, or an inert gas atmosphere. The degreasing process is as follows: under a hydrogen atmosphere (hydrogen flow rate of 300 mL / min), the temperature is raised from room temperature to 380℃ and held for 30 min, then raised to 420℃ and held for 30 min; under an argon atmosphere (argon flow rate of 60 mL / min), the temperature is raised to 530℃ and held for 30 min; then raised to 1140℃ and held for 60 min; under an argon atmosphere and an inert gas pressure of 5 MPa, the temperature is raised to 1485℃ and held for 60 min; finally, the temperature is lowered to room temperature in an argon atmosphere to obtain the cemented carbide sintered body. The performance indicators of the sintered body are listed in Table 1 below. Subsequently, the cemented carbide sintered body is placed in a hot isostatic pressing furnace, heated to 1450℃ at a rate of 20℃ / min, and held at a pressure of 60 MPa for 60 min. The relative density of WC-9Ni cemented carbide (ZN108) increased to 99.8% after hot isostatic pressing.

[0061] Comparative Example 3

[0062] Compared with Example 3, Comparative Example 3 did not undergo surface modification, but was otherwise identical. The WC powder slurry could not be photocured, thus failing to meet the requirements of photocurable additive manufacturing and making it impossible to carry out step S3.

[0063] Example 4

[0064] The steps for additive manufacturing of WC-TiC-TaC-6Co cemented carbide are as follows:

[0065] S1: 200 parts of WC-TiC-TaC solid solution composite powder (D 50 12 parts of Co powder (1500 nm) were added to a three-necked flask containing 30 parts of methyl methacrylate and 600 parts of ethanol solution (ethanol concentration 60%). Then, 0.5 parts of azobisisoheptancyanide were added under a stirring rate of 200 rad / min, and the mixture was heated to 60℃ and reacted for 6 hours. The powder was then filtered out and washed three times with anhydrous ethanol. The powder was then dried in a vacuum drying oven at 60℃ for 24 hours to obtain surface-modified WC-TiC-TaC-6Co cemented carbide powder.

[0066] S2: 800 parts of modified WC-TiC-TaC-6Co cemented carbide powder, 10 parts of PETA, 90 parts of TMPTA, 1 part of initiator 819, 1 part of initiator 184, 6 parts of dispersant KOS-110, and 2 parts of carburizing agent asphalt were added to a ball mill jar and ball-milled at a rate of 300 rad / min to obtain WC-TiC-TaC-6Co cemented carbide slurry. The grinding balls were cemented carbide balls, with a ball-to-material ratio of 1 / 3; the ball milling time was 8 hours.

[0067] S3: After vacuum degassing the cemented carbide slurry for 30 minutes, place it in the material tank of a photopolymerization-based additive manufacturing (DLP) equipment, and then perform additive manufacturing to obtain a WC-TiC-TaC-6Co cemented carbide blank.

[0068] S4: The cemented carbide billet is placed in a furnace for degreasing, conversion, and sintering. The degreasing atmosphere is hydrogen, vacuum, or an inert gas atmosphere. The degreasing process is as follows: under a hydrogen atmosphere (hydrogen flow rate of 450 mL / min), the temperature is raised from room temperature to 360℃ and held for 30 min, then raised to 465℃ and held for 30 min; under an argon atmosphere (argon flow rate of 1400 mL / min), the temperature is raised to 560℃ and held for 30 min; then raised to 1050℃ and held for 60 min; under an argon atmosphere and an inert gas pressure of 5 MPa, the temperature is raised to 1465℃ and held for 60 min; finally, under an argon atmosphere, the temperature is lowered to 80℃ within 300 min to obtain the cemented carbide sintered body. Subsequently, the cemented carbide sintered body is placed in a hot isostatic pressing furnace, heated to 1450℃ at a rate of 10℃ / min, and held at a pressure of 82 MPa for 60 min. The relative density of WC-TiC-TaC-6Co cemented carbide increased to 99.1% after hot isostatic pressing.

[0069] Example 5

[0070] The steps for additive manufacturing of steel-structured cemented carbide are as follows:

[0071] S1: Mix 200 parts WC powder (D)50 A 3000 nm thick powder was added to a three-necked flask containing 25 parts pyridine and 600 parts ethanol solution (70% ethanol concentration). Then, 0.7 parts BPO were added under stirring at 300 rad / min. The mixture was heated to 70°C and reacted for 6 hours. The powder was then filtered and washed three times with anhydrous ethanol. Finally, the powder was dried in a forced-air drying oven at 90°C for 10 hours to obtain surface-modified WC cemented carbide powder.

[0072] S2: 400 parts of modified WC cemented carbide powder, 400 parts of Fe alloy powder (chemical composition: 93% Fe, 2.5% Cr, 2.5% Mo, 2% C), 60 parts of DPGDA, 40 parts of TPGDA, 2 parts of TPO, and 6 parts of dispersant DISPERBYK-164 were added to a ball mill jar and mixed by ball milling at a rate of 300 rad / min to obtain a steel-bonded cemented carbide slurry. The grinding balls were steel balls, with a ball-to-material ratio of 1 / 3; the ball milling time was 12 hours.

[0073] S3: After centrifuging and degassing the steel-bonded cemented carbide slurry for 1 minute, place it in the material tank of a photopolymerization-based additive manufacturing (SLA) equipment, and then perform additive manufacturing to obtain a steel-bonded cemented carbide blank.

[0074] S4: The steel-bonded cemented carbide billet is placed in the furnace for degreasing, conversion, and sintering. The degreasing atmosphere is hydrogen, vacuum, or an inert gas atmosphere. The degreasing process is as follows: under a hydrogen atmosphere (hydrogen flow rate of 400 mL / min), the temperature is raised from room temperature to 330℃ and held for 30 min, then raised to 480℃ and held for 30 min; under an argon atmosphere (argon flow rate of 1000 mL / min), the temperature is raised to 560℃ and held for 30 min; then raised to 1000℃ and held for 60 min; finally, under an argon atmosphere, the temperature is raised to 1320℃ and held for 60 min to obtain the steel-bonded cemented carbide part. The relative density of the steel-bonded cemented carbide is 98.6%. Figure 4 The image shows an additively manufactured steel-structured cemented carbide component.

[0075] Table 2 shows the density of cemented carbide materials produced by additive manufacturing in Examples 1-5 above.

[0076] Group relative density Example 1 99.3％ Example 2 98.9％ Example 3 99.8％ Example 4 99.1％ Example 5 98.6％

[0077] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for additive manufacturing of cemented carbide, characterized in that, Includes the following steps: S1: Screening cemented carbide powder and using organic coating for surface modification to obtain surface-modified cemented carbide powder; the cemented carbide powder D 50 The nm size is 20~5000 nm; the surface modification method is solution polymerization, specifically: adding cemented carbide powder and organic-ethanol aqueous solution to a reaction vessel, adding an initiator while stirring, heating to carry out the reaction, filtering, and drying to obtain surface-modified cemented carbide powder; wherein, the cemented carbide powder is at least one of carbide elemental powder, alloy powder of carbide elemental powder and binder, carbide solid solution powder, and alloy powder of carbide solid solution powder and binder; the organic substance is one or more of butyl acrylate, acrylamide, methyl methacrylate, and pyrrole; the initiator is one or more of ammonium persulfate, azobisisobutyronitrile, benzoyl peroxide, azobisisoheptanecyanide, azobisisobutyramidine hydrochloride, potassium persulfate, and dicumyl peroxide; S2: The surface-modified cemented carbide powder, photosensitive resin monomer, photoinitiator, dispersant and carbon raiser are ball-milled and mixed to obtain a photosensitive slurry; S3: The photosensitive paste is degassed and then transferred to a photopolymerization additive manufacturing equipment for additive manufacturing to obtain a cemented carbide blank; S4: The cemented carbide billet is placed in a furnace for degreasing, conversion and sintering to obtain cemented carbide.

2. The additive manufacturing method for cemented carbide according to claim 1, characterized in that, The mass concentration of the organic matter is 1% to 50% of the organic matter-ethanol aqueous solution; the mass concentration of the initiator is 0.001% to 10% of the organic matter-ethanol aqueous solution; the volume ratio of cemented carbide powder to organic matter-ethanol aqueous solution is 0.01 to 0.6; the mass concentration of ethanol aqueous solution in organic matter-ethanol aqueous solution is 50% to 99%; and the mass concentration of ethanol in ethanol aqueous solution is 20% to 90%.

3. The additive manufacturing method for cemented carbide according to claim 2, characterized in that, The photosensitive resin monomer is one or more of the following: hydroxyethyl acrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, dipropylene glycol diacrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, and dipentaerythritol hexaacrylate; the photoinitiator is one or more of the following: phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 1-hydroxycyclohexylphenyl ketone, trimethylbenzoyl-diphenylphosphine oxide, and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone; the dispersant is one or more of the following: XYS-2800 modified polymer solution, XYS-5800 modified polymer solution, DISPERBYK-164 modified polyurethane solution, TEGO DISPER 655 modified polyether, and Croda, Hypermer. One or more of the following: KD-2, γ-glycidoxypropyltrimethoxysilane, 3-aminopropyltriethoxysilane, block copolymers containing acidic groups, and polymers containing acidic groups.

4. The additive manufacturing method for cemented carbide according to claim 3, characterized in that, The photosensitive resin monomer has a volume solids content of 10% to 90%; the surface-modified cemented carbide powder has a volume solids content of 10% to 90%; the photoinitiator is added at 1% to 10% of the mass of the photosensitive resin monomer; the dispersant is added at 0.1% to 10% of the mass of the surface-modified cemented carbide powder; the carbon raiser is added at 1% to 10% of the mass of the modified cemented carbide powder; the ball-to-material ratio of the ball mill is 0 to 1 / 2, the milling speed is 10 to 2000 rad / min, and the milling time is 1 to 24 h.

5. The additive manufacturing method for cemented carbide according to claim 4, characterized in that, The degassing process is as follows: centrifugal degassing for 1-2 minutes; or vacuum degassing for 10-60 minutes; the photopolymerization additive manufacturing equipment is a stereolithography or digital light processing equipment.

6. The additive manufacturing method for cemented carbide according to claim 5, characterized in that, The degreasing atmosphere is hydrogen, vacuum, or inert gas; the degreasing process is as follows: heat from room temperature to 300~400℃ and hold for 1~60 min, then heat to 400~500℃ and hold for 1~60 min, then heat to 500~600℃ and hold for 1~60 min, then heat to 800~1000℃ and hold for 10~120 min, with a heating rate of 0.01~30℃ / min.

7. The additive manufacturing method for cemented carbide according to claim 6, characterized in that, The sintering atmosphere is vacuum, nitrogen, or argon; the sintering process is as follows: under vacuum, the temperature is raised to 1000~1200℃ and held for 1~60 min, then under an inert gas pressure of 0~10 MPa, the temperature is raised to 1250~1500℃ and held for 60~240 min, and finally the temperature is lowered to 80℃ within 200~300 min, with a heating rate of 0.01~30℃ / min.

8. The additive manufacturing method for cemented carbide according to claim 7, characterized in that, It also includes densification treatment of sintered cemented carbide by hot isostatic pressing; the hot isostatic pressing temperature is 1300~2000℃, the time is 30~120min, and the pressure is 10~100Mpa.

9. A cemented carbide obtained by the additive manufacturing method according to any one of claims 1 to 8.

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