A high melting point metal and its additive manufacturing method

Abstract

A high-melting-point metal and its additive manufacturing method belong to the field of direct ink writing additive manufacturing. It is prepared by using a direct ink writing additive manufacturing device. The additive manufacturing model is drawn by the software Cinema 4D, and the operating parameters are set by the Simplify3D software; the nozzle diameter is 0.2 mm to 1 mm, the extrusion line width is 0.2 mm to 1 mm, the layer height is not less than 0.15 mm to 0.7 mm, the first layer height, the first layer extrusion line width, and the first layer printing speed reduction ratio are all 100%, the filling density is 40% to 100%, the filling wire angle is 45° and -45°, the default printing speed is set to 50 mm / s, the moving speeds of the x, y, and z axes are all 100 mm / s, and the extrusion air pressure is not higher than 0.5 MPa. The sample after additive manufacturing is heated to 110~120 °C in air and kept warm for 48 h~72 h, and then heated to 800 °C in an argon atmosphere and kept warm for 1 h~2 h for high-temperature debinding; finally, it is heated to the sintering temperature in an argon atmosphere to obtain a high-melting-point metal additive manufacturing product.

Description

Technical Field

[0001] The present invention relates to the field of inkjet direct writing additive manufacturing, and particularly provides a high melting point metal and an additive manufacturing method thereof. Background Art

[0002] Currently, for the melting-based additive manufacturing method, metal powder needs to be melted during the printing process, thus requiring a high concentration of energy. In addition, an inert gas is needed to prevent oxidation during the printing process. This places relatively high requirements on equipment and the site. Therefore, most of the additive manufacturing equipment using the melting method is expensive and has high maintenance costs.

[0003] In view of the high cost problem of the melting-based additive manufacturing method, inkjet direct writing additive manufacturing has emerged in recent years. This method can be understood as follows: a metal powder and an organic matter are mixed to obtain an ink or slurry, and the slurry is extruded at a preset position and stacked layer by layer to obtain a preform, and then debinding and sintering are performed to obtain the final product. Currently, most of the inkjet direct writing additive manufacturing technologies applied to the metal field use dichloromethane (DCM) as a solvent and poly(lactic-co-glycolic acid) (PLGA) as a dispersant. PLGA has good dispersibility for metal and metal oxide powders and can be completely removed during the heating process. However, the cost of PLGA is quite high and it cannot be adapted to large-scale production. In addition, the printing ink using DCM solvent cannot be stored for a long time due to the high volatility of DCM, and the volatilization of DCM pollutes the environment. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the present invention provides a high melting point metal and an additive manufacturing method thereof.

[0005] The technical solution of the present invention is as follows:

[0006] An additive manufacturing method for a high melting point metal is prepared by using an inkjet direct writing additive manufacturing device. The additive manufacturing model is drawn by the software Cinema 4D, and the operating parameters are set by the Simplify3D software;

[0007] The slurry used is composed of tungsten / high entropy alloy mixed powder, polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), cellulose, glycerol, and deionized water.

[0008] The nozzle diameter is 0.2 mm to 1 mm, the extrusion line width is 0.2 mm to 1 mm, the layer height is 0.15 mm to 0.7 mm, the first layer height, the first layer extrusion line width, and the first layer printing speed reduction ratio are all 100%, the filling density is 40% to 100%, the filling wire angle is 45° and -45°, the default printing speed is set to 50 mm / s, the moving speeds of the x, y, and z axes are all 100 mm / s, and the extrusion air pressure is not higher than 0.5 Mpa;

[0009] Heat the sample after additive manufacturing in air to 110°C - 120°C and hold for 48h - 72h, then heat it to 800°C in an argon atmosphere and hold for 1h - 2h for high-temperature debinding; heat it to 1450°C - 1500°C in an argon atmosphere, and a high-melting-point metal additive manufacturing product is obtained after holding for 1h.

[0010] As a preferred technical solution:

[0011] In the slurry, relative to every 100 parts by weight of the tungsten / high-entropy alloy mixed powder, the addition amount of polyvinyl alcohol is 0.34 - 1.13 parts by weight, the addition amount of polyvinylpyrrolidone is 0.11 - 0.56 parts by weight, the addition amount of cellulose is 0.12 - 0.98 parts by weight, the addition amount of glycerol is 9 - 21 parts by weight, and the addition amount of deionized water is 1.5 - 6.5 parts by weight.

[0012] The particle size of the tungsten / high-entropy alloy mixed powder is 2μm - 4μm.

[0013] The system of the high-entropy alloy is FeCoNi, FeCoNiCr, FeCoNiCrMn, FeCoNiAlMn, FeCoNiCuAl, or FeCoNiCrAlMnCu, and most preferably FeCoNiCr high-entropy alloy.

[0014] The cellulose is prepared from loofah by bleaching, pickling, alkali washing, and freeze-drying.

[0015] The present invention also provides a high-melting-point metal prepared by the above method. The high-melting-point metal has a reticulated porous structure, has a metallic luster, and its compressive fracture limit is 300MPa.

[0016] The present invention has the following remarkable features compared with the prior art:

[0017] 1. The present invention can prepare an additive manufacturing sample of a high-melting-point metal (such as W) at room temperature. Compared with melting-based additive manufacturing, the structure of this equipment is simple and the cost is low. In the later sintering process of room-temperature additive manufacturing, compared with the direct melting additive manufacturing method, the generated stress is greatly reduced, making the additive manufacturing of high-melting-point metals more simplified.

[0018] 2. The slurry of the present invention does not contain volatile substances, has strong stability compared with the slurry using DCM as a solvent, and the slurry can be stored for a long time.

[0019] 3. The printing equipment and slurry used in the present invention have greatly reduced costs compared with the existing printing technologies.

[0020] 4. The present invention is safe and environmentally friendly, does not contain volatile hazardous solvents, and will not cause serious harm to the health of operators.

[0021] 5. The high melting point metal prepared by using the slurry of the present invention has a reticulated porous structure, has a metallic luster, and its compressive fracture limit is as high as 300 MPa. Description of the Drawings

[0022] Figure 1 It is a 3D printed product of tungsten / high entropy alloy slurry after sintering at 1450 °C in Example 1.

[0023] Figure 2 It is the compressive mechanical property curve of the tungsten / high entropy printed product sintered at 1450 °C in Example 1.

[0024] Figure 3 It is the dried green body of the 3D printed product obtained in Comparative Example 1.

[0025] Figure 4 It is a 3D printed product of tungsten / high entropy alloy slurry sintered at 1500 °C in Example 2.

[0026] Figure 5 It is the microstructural diagram of the tungsten / cobalt-chromium-iron-nickel 3D printed product after sintering in Example 2.

[0027] Figure 6 It is a 3D printed product of tungsten / high entropy alloy slurry after sintering at 1600 °C in Comparative Example 2. Detailed Embodiments

[0028] The preferred embodiments of the present invention will be described in detail below. Although the following description is the preferred embodiment of the present invention, it should be understood that the present invention can be implemented in other ways and should not be limited by this method.

[0029] Unless otherwise specified, the cellulose described in the embodiments of the present invention is prepared from loofah sponge as raw material through bleaching, pickling, alkali washing and freeze drying.

[0030] Example 1

[0031] (1) Tungsten, cobalt, chromium, iron, and nickel powders with a particle size of 2 μm to 4 μm are mixed in an atomic ratio of 55:11.25:11.25:11.25:11.25; a PVA / Gl solution mixture with a concentration of 60 mg / ml is prepared, and the PVA / Gl mixture is heated to 150 °C in an oil bath and stirred for 3 h to obtain a jelly-like PVA / Gl solution mixture; a cellulose / PVP / aqueous solution is prepared, where the concentration of cellulose is 100 mg / mL; the concentration of PVP is 80 mg / mL; the metal powder, PVA / Gl solution mixture, and cellulose / PVP / aqueous solution are mixed to obtain the slurry for printing, and the weight parts of each component are as shown in the following table.

[0032] Table 1 Slurry Composition Ratio

[0033]

[0034] (2)Draw a porous cube using Cinema 4D software, and export the model in STL format after drawing. Import the STL format model into Simplify3D slicing software, and set the printing parameters through Simplify3D software. The specific additive manufacturing parameters are as follows: nozzle diameter 0.4mm, extrusion line width 0.4mm, layer height 0.35mm, first layer height, first layer extrusion line width, and first layer printing speed reduction ratio are all 100%, filling density 60%, filling wire angle is 45° and -45°, default printing speed is set to 50mm / s, x, y, and z axis movement are all 100mm / s, and extrusion air pressure is 0.4MPa. After setting all the additive manufacturing parameters, export the model in Gcode format and import it into the additive manufacturing equipment for standby.

[0035] (3)Fill the slurry into the material tube of the additive manufacturing equipment, and let it stand for 24h to remove air bubbles. Then install the front end of the material tube on the extrusion device, connect the rear end to an air pump, adjust the air pressure to 0.4MPa, and then start printing the product. The freshly printed product has no strength.

[0036] (4)Heat the additively manufactured sample to 120°C in an air atmosphere and keep it warm for 48 hours. After a long period of heat preservation, most of the Gl slowly evaporates. Then heat the sample to 800°C in an argon atmosphere and keep it warm for 1h for debinding. Use an MRF5299 high-temperature and high-vacuum hot pressing furnace for final sintering. The debound product is sintered at 1450°C for 1h in an argon atmosphere, and finally an additively manufactured product of tungsten / high-entropy alloy composite is obtained, as Figure 1 shown. The compressive fracture limit of the product is 300MPa, as Figure 2 shown.

[0037] Comparative Example 1

[0038] The preparation, printing, and drying methods of the tungsten / high-entropy alloy slurry in this Comparative Example 1 refer to Example 1, except that the heating temperature in the air atmosphere is controlled at 130°C, which is higher than the maximum value of 120°C required by the present invention. It can be seen from Figure 3 that the sample dried at 130°C in this Comparative Example 1 softened due to the high drying temperature, and collapsed during the drying process, while the sample dried at 120°C in Example 1 had a good appearance and did not collapse.

[0039] Example 2

[0040] The preparation, printing, drying, debinding, and sintering methods of the tungsten / high-entropy alloy slurry refer to Example 1, except that the sintering temperature is controlled at 1500°C. From Figure 4It can be seen from [reference] that the sample sintered at 1500 °C in this embodiment still maintains the designed structure and does not collapse during the sintering process. The microstructure of the product after sintering is as shown in Figure 5 shown.

[0041] Comparative Example 2

[0042] The preparation, printing and drying methods of the tungsten / high-entropy alloy slurry in this Comparative Example 2 refer to Example 1, except that the sintering temperature is controlled at 1600 °C, which is higher than the maximum value of 1500 °C required by the present invention. It can be seen from Figure 6 that in this Comparative Example 2, at 1600 °C, the high-entropy alloy undergoes partial melting, and the product is severely deformed and collapses during the sintering process. The products in Example 1 and Example 2 have good appearance after sintering at 1450 °C and 1500 °C respectively and do not collapse.

[0043] Example 3

[0044] (1) Take tungsten powder with a particle size of 2 μm to 4 μm and FeCoNiCrMn high-entropy alloy powder and mix them in an atomic ratio of 1:1; prepare a PVA / Gl solution mixture with a concentration of 70 mg / ml, heat the PVA / Gl mixture in an oil bath to 150 °C and stir for 3 h to obtain a jelly-like PVA / Gl solution mixture; prepare a cellulose / PVP / aqueous solution, where the concentration of cellulose is 100 mg / mL; the concentration of PVP is 80 mg / mL; mix the metal powder, PVA / Gl solution mixture, and cellulose / PVP / aqueous solution to obtain the slurry for printing. The weight parts of each component are as shown in the following table.

[0045] Table 2 Slurry composition ratio

[0046]

[0047] (2) Draw a porous cube through Cinema 4D software, and export it as an STL format model after drawing. Import the STL format model into Simplify3D slicing software, and set the printing parameters through Simplify3D software. The specific additive manufacturing parameters are as follows: nozzle diameter 0.25 mm, extrusion line width 0.25 mm, layer height 0.20 mm, the first layer height, the first layer extrusion line width, and the first layer printing speed reduction ratio are all 100%, filling density 90%, filling wire angle is 45° and -45°, the default printing speed is set at 50 mm / s, the x, y, and z axis movements are all 100 mm / s, and the extrusion air pressure is 0.4 MPa. After setting all the additive manufacturing parameters, export it as a Gcode format model and import it into the additive manufacturing equipment for use.

[0048] (3) Fill the slurry into the material tube of the additive manufacturing equipment and let it stand for 24 h to remove air bubbles. Then install the front end of the material tube on the extrusion device, connect the back end to an air pump, adjust the air pressure to 0.4 MPa, and then start printing the product. The product just printed has no strength.

[0049] (4) Heat the additively manufactured sample to 110 °C in an air atmosphere and keep it warm for 60 hours. After a long time of heat preservation, most of the Gl slowly evaporates. Then heat the sample to 800 °C in an argon atmosphere and keep it warm for 1.5 h for debinding. Use an MRF5299 high-temperature and high-vacuum hot pressing furnace for final sintering. The debound product is sintered at 1450 °C for 1 h in an argon atmosphere to finally obtain an additively manufactured product of tungsten / high-entropy alloy composite material.

[0050] Example 4

[0051] (1) Mix tungsten, iron, cobalt, nickel, copper, and aluminum powders with a particle size of 2 μm to 4 μm in an atomic ratio of 50:10:10:10:10:10; configure a PVA / Gl solution mixture with a concentration of 60 mg / ml, heat the PVA / Gl mixture in an oil bath to 150 °C and stir for 3 h to obtain a jelly-like PVA / Gl solution mixture; prepare a cellulose / PVP / aqueous solution, where the concentration of cellulose is 130 mg / mL; the concentration of PVP is 90 mg / mL; mix the metal powder, PVA / Gl solution mixture, and cellulose / PVP / aqueous solution to obtain the slurry for printing. The weight parts of each component are as shown in the following table.

[0052] Table 3 Slurry composition ratio

[0053]

[0054] (2) Draw a porous cube through Cinema 4D software, and export the drawn model as an STL format model after drawing. Import the STL format model into Simplify3D slicing software, and set the printing parameters through Simplify3D software. The specific additive manufacturing parameters are as follows: nozzle diameter 1.0 mm, extrusion line width 1.0 mm, layer height 0.7 mm, first layer height, first layer extrusion line width, and first layer printing speed reduction ratio are all 100%, filling density 40%, filling wire angle is 45° and -45°, default printing speed is set to 50 mm / s, x, y, and z axis movements are all 100 mm / s, and extrusion air pressure is 0.4 MPa. After setting all the additive manufacturing parameters, export them as a Gcode format model and import them into the additive manufacturing equipment for use.

[0055] (3) Fill the slurry into the material tube of the additive manufacturing equipment and let it stand for 24 h to remove air bubbles. Then install the front end of the material tube on the extrusion device, connect the back end to an air pump, adjust the air pressure to 0.4 MPa, and then start printing the product. The product just printed has no strength.

[0056] (4) Heat the additively manufactured sample to 110 °C in an air atmosphere and hold for 72 h. After a long time of holding, most of the Gl slowly evaporates. Then heat the sample to 800 °C in an argon atmosphere and hold for 2 h for debinding. Use an MRF5299 high-temperature and high-vacuum hot pressing furnace for final sintering. The debound product is sintered at 1500 °C for 1 h in an argon atmosphere to finally obtain an additively manufactured product of tungsten / high-entropy alloy composite.

[0057] Matters not covered in this invention are well-known technologies.

[0058] The above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. An additive manufacturing method for high melting point metals, characterized in that: It is prepared by using an inkjet direct writing additive manufacturing equipment. The additive manufacturing model is drawn by the software Cinema 4D, and the operation parameters are set by the Simplify3D software; The slurry used is composed of tungsten / high entropy alloy mixed powder, polyvinyl alcohol, polyvinylpyrrolidone, cellulose, glycerol and deionized water; The nozzle diameter is 0.2 mm to 1 mm, the extrusion line width is 0.2 mm to 1 mm, the layer height is 0.15 mm to 0.7 mm, the first layer height, the first layer extrusion line width and the first layer printing speed reduction ratio are all 100%, the filling density is 40% to 100%, the filling path angle is 45° and -45°, the default printing speed is set to 50 mm / s, the moving speeds of the x, y, and z axes are all 100 mm / s, and the extrusion air pressure is not higher than 0.5 Mpa; The sample after additive manufacturing is heated to 110 °C to 120 °C in air and kept warm for 48 h to 72 h, and then heated to 800 °C in an argon atmosphere and kept warm for 1 h to 2 h for high-temperature debinding; it is heated to 1450 °C to 1500 °C in an argon atmosphere and kept warm for 1 h to obtain a high melting point metal additive manufacturing product; in the slurry, relative to every 100 parts by weight of the tungsten / high entropy alloy mixed powder, the addition amount of polyvinyl alcohol is 0.34 to 1.13 parts by weight, the addition amount of polyvinylpyrrolidone is 0.11 to 0.56 parts by weight, the addition amount of cellulose is 0.12 to 0.98 parts by weight, the addition amount of glycerol is 9 to 21 parts by weight, and the addition amount of deionized water is 1.5 to 6.5 parts by weight.

2. The additive manufacturing method of the high melting point metal according to claim 1, wherein: The particle size of the tungsten / high entropy alloy mixed powder is 2 μm to 4 μm.

3. The additive manufacturing method of the high melting point metal according to claim 1, characterized in that: The system of the high entropy alloy is FeCoNi, FeCoNiCr, FeCoNiCrMn, FeCoNiAlMn, FeCoNiCuAl or FeCoNiCrAlMnCu.

4. The additive manufacturing method of the high melting point metal according to claim 1, characterized in that: The cellulose is prepared from loofah sponge as raw material through bleaching, pickling, alkali washing and freeze drying.

5. A high melting point metal prepared by the method according to claim 1, characterized in that: The high melting point metal is a reticulated porous structure and has a metallic luster.

6. The high melting point metal according to claim 5, characterized in that: The compressive fracture limit of the high melting point metal is 300 MPa.

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