High-entropy alloy slurry for ink direct writing additive manufacturing and preparation method thereof

Abstract

The application provides a high-entropy alloy slurry for ink direct writing additive manufacturing and a preparation method thereof, and belongs to the technical field of 3D printing forming. The slurry is composed of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), cellulose, glycerol, deionized water and high-entropy alloy powder. Compared with existing room temperature additive manufacturing technology, the application effectively improves the stability of the slurry, reduces the production cost, is simple to operate, has low requirements on protective facilities, is very safe and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The application discloses a high-entropy alloy slurry for ink direct writing additive manufacturing and a preparation method thereof, and belongs to the technical field of 3D printing forming. BACKGROUND

[0002] Currently, existing additive manufacturing technologies are mainly divided into two categories. The first is a melting method-based additive manufacturing technology, which is mainly applied to metal and polymer materials. The other is a sintering method-based additive manufacturing technology, which is mainly applied to metal and ceramic materials.

[0003] (1) Melting method-based additive manufacturing

[0004] For metal materials, the method can be divided into two categories: powder feeding printing and powder laying printing. Powder feeding printing refers to melting and depositing powder raw materials at a specific location while the powder raw materials pass through the nozzle, and finally obtaining the final product through layer-by-layer stacking. This method is similar to laser cladding, and has the advantages of fast printing speed, large size of the product, and high strength of the product immediately after printing. However, the method has the disadvantages of poor precision, great internal stress for printing high-melting-point metals, and inability to eliminate stress during the printing process, which leads to uncontrollable deformation or even cracks of the printed product. Powder laying printing refers to laying powder raw materials, then melting the powder at a specific location, laying another layer of powder, melting the powder at the specific location, and finally obtaining the printed product through layer-by-layer stacking. Compared with powder feeding printing, powder laying printing has higher precision, but its disadvantages are also obvious. The method still cannot solve the problem of internal stress, and a large amount of powder raw materials are needed, which leads to high production cost.

[0005] (2) Sintering method-based additive manufacturing

[0006] For metal materials, the category method can be divided into two kinds. The first method is similar to the powder laying printing based on melting method, which is also to lay powder with metal powder as raw material, the difference is that the method is to extrude the binder to the specific position of the powder bed, lay powder, bond, and stack layer by layer to get the preform, and then get the final product through debinding and sintering. The advantage is that there is no stress in the printing process, and the precision is high, the product is uniformly heated in the sintering process, the stress is small, the product shrinks uniformly, and the uncontrollable deformation is small. The disadvantage is low powder utilization rate and high cost. The second method is a new inkjet additive manufacturing method emerging in recent years, which is to add solvent, dispersant, thickener, lubricant and other additives to the metal powder to prepare printing ink or slurry, and then extrude the ink or slurry to the preset position through the nozzle, and then get the preform by layering, and then get the final product by debinding and sintering. The existing inkjet additive manufacturing ink mainly uses dichloromethane as the solvent, the advantage is that dichloromethane is extremely volatile, the extruded ink will dry quickly, and dichloromethane can dissolve many dispersants and thickeners, so it is widely used as a solvent in this field. But dichloromethane is toxic, and because it is volatile, the additive manufacturing equipment must have a protection device, which greatly increases the cost. In addition, due to the volatility of dichloromethane, the printing ink can only be prepared on demand, and cannot be stored for a long time. Furthermore, the volatile slurry will also volatilize in the barrel, which will change the viscosity of the ink during printing, affecting the product quality. SUMMARY

[0007] In order to overcome the deficiencies in the prior art, the present application provides a high-entropy alloy slurry for inkjet additive manufacturing and a preparation method thereof.

[0008] The technical scheme of the present application is as follows:

[0009] A high-entropy alloy slurry for inkjet additive manufacturing, characterized in that the slurry is composed of polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), cellulose, glycerol, deionized water and high-entropy alloy powder.

[0010] As a preferred technical scheme:

[0011] The addition amount of glycerol is 15-25 parts by weight, the addition amount of polyvinyl alcohol is 0.57-1.35 parts by weight, the addition amount of deionized water is 1-6 parts by weight, the addition amount of polyvinylpyrrolidone is 0.07-0.54 parts by weight, and the addition amount of cellulose is 0.08-0.9 parts by weight, relative to 100 parts by weight of high-entropy alloy powder.

[0012] The cellulose is prepared from loofah sponge as raw material by bleaching, pickling, alkali washing, freezing and drying.

[0013] The particle size of the high-entropy alloy powder is 2-4 microns.

[0014] The high-entropy alloy is one or more of FeCoNi, FeCoNiCr, FeCoNiCrMn, FeCoNiAlMn, FeCoNiCuAl, FeCoNiCrAlMnCu, etc. in atomic ratio or near atomic ratio, and most preferably is a cobalt-chromium-iron-nickel high-entropy alloy, in which the atomic ratio of cobalt, chromium, iron and nickel is 25:25:25:25.

[0015] The application also provides a preparation method of the high-entropy alloy slurry for inkjet direct additive manufacturing, characterized in that:

[0016] First, a polyvinyl alcohol / glycerol solution is prepared, in which the concentration of polyvinyl alcohol is 50-70 mg / mL; the mixed polyvinyl alcohol / glycerol is heated to 130-160 DEG C in an oil bath and stirred at the same time for 3-5 h to make the polyvinyl alcohol completely dissolved; then a cellulose / polyvinylpyrrolidone / water solution is prepared, in which the concentration of cellulose is 80-150 mg / mL; the concentration of polyvinylpyrrolidone is 70-90 mg / mL; finally, the high-entropy alloy powder, the polyvinyl alcohol / glycerol solution and the cellulose / polyvinylpyrrolidone / water solution are mixed to prepare the slurry for inkjet direct additive manufacturing.

[0017] The slurry is suitable for additive manufacturing at room temperature followed by debinding and sintering to prepare an additive manufacturing product, and the printing error can be controlled within 0.3 mm.

[0018] Compared with the prior art, the application has the following remarkable features:

[0019] 1. The additive manufacturing product can be prepared at room temperature, and the stress generated in the sintering process after room temperature additive manufacturing is greatly reduced compared with the direct melting additive manufacturing method, so that the additive manufacturing high-entropy alloy product is more simple.

[0020] 2. Compared with the existing laser melting powder laying printing technology, the powder consumption is greatly reduced, and the product manufacturing cost is greatly reduced. In addition, the printing equipment is relatively simple, and the equipment cost is low.

[0021] 3. Compared with the existing powder laying printing technology using a binder, the powder consumption is greatly reduced, and the product manufacturing cost is greatly reduced.

[0022] 4. The slurry does not contain volatile substances, has very strong stability compared with the slurry using DCM as a solvent, and can be stored for a long time.

[0023] 5. The slurry does not contain toxic substances, has very good safety compared with the slurry using DCM as a solvent, is very environmentally friendly, only produces waste gas in the debinding process, and the collection of waste gas is also very convenient.

[0024] 6. The non-toxic and non-volatile additive manufacturing slurry of the present application has higher stability, lower requirements for additive manufacturing equipment, simple operation, low requirements for protective facilities, is very safe and environmentally friendly, and reduces the production cost of products. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The 3D printed product just printed for Example 1.

[0026] Figure 2 The 3D printed product just printed for Comparative Example 1. DETAILED DESCRIPTION

[0027] The preferred embodiments of the present application will be described in detail below, although the following description is for the preferred embodiments of the present application, it should be understood that the present application can be implemented in other ways, and should not be limited by the present method.

[0028] Example 1

[0029] (1) A PVA / Gl solution mixture with a concentration of 60 mg / ml was prepared, and the PVA / Gl mixture was heated to 150°C in an oil bath and stirred for 3 h to fully dissolve the PVA, obtaining a jelly-like PVA / Gl solution mixture.

[0030] (2) Cobalt, chromium, iron and nickel powders with a particle size of 2-4 μm were mixed in an atomic ratio of 25:25:25:25.

[0031] (3) A cellulose / PVP / deionized water solution was prepared, with a cellulose concentration of 100 mg / mL and a PVP concentration of 80 mg / mL.

[0032] (4) The high-entropy alloy mixed powder, PVA / glycerol solution, and cellulose / PVP / deionized water solution were mixed in a mass ratio of 30:7:2 to prepare a slurry for inkjet direct writing additive manufacturing.

[0033] (5) The simplify3D software was used to set the printing program, with a nozzle diameter of 0.4 mm, a layer height of 0.3 mm, a filling rate of 60%, a filling trace angle of 45° and -45°, and a printing speed of 20 mm / s. The additive manufacturing was carried out on an inkjet 3D printer, and the product just printed is shown in Figure 1 . Subsequently, drying, debinding and sintering were carried out to obtain the final product. The printing accuracy of the product can be controlled within 0.3 mm, and the linear shrinkage rate of the product after sintering is 14% compared with the product just printed.

[0034] Example 2

[0035] The difference from Example 1 is that:

[0036] The selected high-entropy alloy powder is CoCrFeNiCu, and the atomic ratio between each component is 20:20:20:20:20. The printing precision of the product can be controlled within 0.3 mm, and the linear shrinkage rate of the product after sintering compared with the product just printed is 14%.

[0037] Example 3

[0038] The difference from Example 1 is that the selected high-entropy alloy powder is CoCrFeNiMn, and the atomic ratio between each component is 20:20:20:20:20. The printing precision of the product can be controlled within 0.3 mm, and the linear shrinkage rate of the product after sintering compared with the product just printed is 14%.

[0039] Comparative Example 1

[0040] (1) A PVA / Gl solution mixture with a concentration of 60 mg / ml was prepared, and the PVA / Gl mixture was heated to 150°C in an oil bath and stirred for 3 h to fully dissolve the PVA, obtaining a jelly-like PVA / Gl solution mixture.

[0041] (2) Cobalt, chromium, iron, and nickel powders with a particle size of 2-4 μm were mixed in an atomic ratio of 25:25:25:25.

[0042] (3) The mixed CoCrFeNi powder was mixed with the PVA / Gl solution, and the content of glycerol in the slurry was 30 parts by weight and the content of PVA was 1.4 parts by weight relative to 100 parts by weight of the CoCrFeNi powder.

[0043] (4) A porous network structure was printed in an ink direct writing 3D printer, and the extrusion filament diameter was 0.8 mm. Experimental results showed that 0.8 mm was the minimum value at which the slurry could be smoothly extruded. The formability of the product was poorer than that of Example 1, the layers fused together, and the designed model could not be realized, as shown in Figure 2

[0044] The remaining matters of the present application are known technologies.

[0045] The above examples are only for illustrating the technical concepts and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and it cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application should be covered within the protection scope of the present application.​

Claims

1. A high entropy alloy slurry for ink direct writing additive manufacturing, characterized by: The slurry consists of polyvinyl alcohol, polyvinyl pyrrolidone, cellulose, glycerol, deionized water and high entropy alloy powder; relative to every 100 parts by weight of the high entropy alloy powder, the amount of glycerol added is 15 to 25 parts by weight, the amount of polyvinyl alcohol added is 0.57 to 1.35 parts by weight, the amount of deionized water added is 1 to 6 parts by weight, the amount of polyvinyl pyrrolidone added is 0.07 to 0.54 parts by weight, and the amount of cellulose added is 0.08 to 0.9 parts by weight; The preparation method is as follows: first, prepare a polyvinyl alcohol / glycerol solution, in which the concentration of polyvinyl alcohol is 50-70 mg / mL; heat the mixed polyvinyl alcohol / glycerol in an oil bath to 130-160°C and stir for 3-5 hours to completely dissolve the polyvinyl alcohol; then prepare a cellulose / polyvinyl pyrrolidone / deionized water solution, in which the concentration of cellulose is 80-150 mg / mL; the concentration of polyvinyl pyrrolidone is 70-90 mg / mL; finally, mix the high entropy alloy powder, the polyvinyl alcohol / glycerol solution and the cellulose / polyvinyl pyrrolidone / deionized water solution to prepare a slurry for ink direct writing additive manufacturing.

2. The high entropy alloy slurry for ink direct writing additive manufacturing according to claim 1, characterized in that: The cellulose is prepared from loofah sponge as a raw material through bleaching, acid washing, alkali washing, freezing and drying.

3. The high entropy alloy slurry for ink direct writing additive manufacturing according to claim 1, characterized in that: The particle size of the high entropy alloy powder is 2-4 μm.

4. The high entropy alloy slurry for ink direct writing additive manufacturing according to claim 1, characterized in that: The high entropy alloy is one or more of FeCoNi, FeCoNiCr, FeCoNiCrMn, FeCoNiAlMn, FeCoNiCuAl, and FeCoNiCrAlMnCu.

5. The high entropy alloy slurry for ink direct writing additive manufacturing according to claim 4, characterized in that: The high entropy alloy is a cobalt-chromium-iron-nickel high entropy alloy.

6. The high entropy alloy slurry for ink direct writing additive manufacturing according to claim 5, characterized in that: The atomic ratio of cobalt, chromium, iron and nickel in the cobalt-chromium-iron-nickel high entropy alloy is 25:25:25:

25.

7. An application of the slurry according to claim 1, characterized in that: The slurry is suitable for additive manufacturing at room temperature and subsequent debinding and sintering to prepare additive manufacturing products.

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