Preparation process and production method of powder for 3D printing graphite material

Abstract

The invention relates to the related technical field of 3D printing, in particular to a preparation process and a production method of powder for a 3D printing graphite material. According to the preparation process and the production method of the powder for the 3D printing graphite material, high-temperature asphalt and other coke powder are proportioned to serve as raw materials of 3D printing powder; the problems that conventional asphalt is low in softening point and complex structural parts are difficult to form in the printing process are effectively solved, the sphericity and fluidity of powder are effectively improved through a mechanical shaping method, the stacking density and the tap density of the powder are improved by combining the scientific powder particle size ratio, and the mechanical shaping method is suitable for industrial production. The body density of a green body of the 3D printing graphite material prepared from the powder is relatively high; meanwhile, the spheroidizing and shaping powder process is high in production efficiency, the preparation process is simple and controllable, and low-cost production is easy to realize.

Description

Technical Field

[0001] The present invention relates to the technical field related to 3D printing, and in particular to a preparation process and production method for powders used in 3D printing of graphite materials. Background Art

[0002] Artificial graphite materials have low hardness, stable chemical properties, are not easily reactive with agents such as acids and alkalis, are resistant to high temperatures, corrosion, thermal shock, radiation, have high strength, good toughness, and also have physical and chemical properties such as self-lubrication, conductivity, and heat conduction. Especially special graphite materials are widely used in fields such as metallurgy, machinery, electronics, military, national defense, aerospace, etc. At present, the production of special graphite materials mostly adopts traditional carbon processes: raw material crushing - screening - kneading - secondary crushing - isostatic pressing - roasting (impregnation) - graphitization, with a long production cycle, high energy consumption, and most products need to be machined before they can be put into use, resulting in a high processing cost.

[0003] 3D printing technology has inherent advantages in the manufacturing of complex-shaped structures. Combining the advantages of 3D printing technology with graphite materials, and utilizing the advantages of 3D printing in structure control, carbon materials with different structural forms can be constructed. Currently, the 3D printing technologies applicable to graphite materials mainly include selective laser sintering forming technology, binder jetting forming technology, and ink direct writing forming technology, etc. And the binder jetting forming technology has the advantages of high efficiency, low cost, and relatively high structural strength in 3D printing of graphite materials, and is suitable for printing large structural parts. To smoothly carry out the 3D printing technology of graphite materials and at the same time ensure the use performance of 3D printed graphite materials, therefore, there is a particular need for a preparation process and production method for powders used in 3D printing of graphite materials.

[0004] Because currently in China, there is still no way to print a graphite formed blank with reliable structural performance. The reason is that the preparation process of spherical powders for 3D printing is difficult to break through, and the finished product rate of printed graphite products is low and the comprehensive performance is poor. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation process and production method for powders used in 3D printing of graphite materials to solve the problems raised in the above background art.

[0006] To achieve the above purpose, the present invention provides a preparation process for powders used in 3D printing of graphite materials, which is carried out according to the following steps: S1. Raw material treatment process; S2. Batching and kneading process; S3. Powder preparation process.

[0007] Preferably, the S1 raw material treatment process is carried out according to the following steps: C1. Crush calcined petroleum coke, calcined pitch coke, artificial graphite, and natural graphite, and then pulverize them with a jet mill. C2. Perform ball milling and shaping on the above pulverized materials through a ball mill. After ball milling, the surfaces of the powder particles are smoother, preparing for subsequent coating. C3. Classify the particle size of the ball-milled powder. Separate the powder, and the coarser raw materials continue to enter the ball mill for ball milling. Repeat the above process. C4. Select high-temperature pitch, dry it, crush it with a crusher, and pulverize it with a jet mill.

[0008] Preferably, the S2 batching and kneading process is carried out according to the following steps: A1. Batch the above-classified raw materials in different proportions. A2. Add the above-prepared materials into a high-speed VC mixer for mixing. After mixing, put the materials into a high-temperature kneading machine and knead them at high temperature. During the kneading process, nitrogen needs to be continuously introduced. After kneading, the paste needs to be quickly rolled into sheets.

[0009] Preferably, the S3 powder preparation process is carried out according to the following steps: B1. Crush the above-prepared sheets and pulverize them with an impact jet mill. B2. Mechanically shape the above powder. B3. Perform air classification on the shaped powder. The air classification adopts three-stage classification. B4. Classification and compounding: B5. Powder mixing. Use a high-speed mixer to mix the above ratios. B6. After uniform mixing, powders with different ratios can be used to meet different printing requirements.

[0010] Preferably, D1. Print the uniformly mixed powder through a specific 3D printing device. During the printing process, the performance of the printed parts can be precisely controlled by adjusting the powder ratio and printing parameters such as layer thickness and printing speed.

[0011] Preferably, the main ratios in A1 are as follows: 60% calcined petroleum coke and 40% high-temperature pitch; 60% calcined pitch coke and 40% high-temperature pitch; 60% artificial graphite and 40% high-temperature pitch; 60% natural graphite and 40% high-temperature pitch.

[0012] Preferably, in B2, the shaping parameters and particle size control ranges are as follows: Shaping times 1: Feed particle size range: 30 - 300 μm, discharge particle size range: 30 - 280 μm; Shaping times 2: Feed particle size range: 30 - 280 μm, discharge particle size range: 32 - 240 μm; Number of shaping times 3: Feed particle size range: 32 - 240 μm, Discharge particle size range: 35 - 210 μm; Number of shaping times 4: Feed particle size range: 35 - 210 μm, Discharge particle size range: 40 - 180 μm.

[0013] Preferably, in B3, air classification is carried out in three stages, and the above-mentioned powder is classified into the following particle size ranges: Powder 1: First-stage classification, Discharge particle size range: 150 - 180 μm; Powder 2: Second-stage classification, Discharge particle size range: 100 - 150 μm; Powder 3: First-stage classification, Discharge particle size range: 50 - 100 μm.

[0014] Preferably, for the classification and compounding in B4, the above-mentioned powders are compounded according to the following principles: Ratio 1: Powder 1: 20%; Powder 2: 30%; Powder 3: 50%; Ratio 1: Powder 1: 30%; Powder 2: 30%; Powder 3: 40%; Ratio 1: Powder 1: 40%; Powder 2: 30%; Powder 3: 30%.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention uses high-temperature asphalt and other coke powder ratios as raw materials for 3D printing powder, effectively solving the problems of low softening point of conventional asphalt and difficulty in forming complex structural parts during the printing process.

[0016] 2. The present invention uses a mechanical shaping method to effectively improve the sphericity and fluidity of the powder. Combined with a scientific powder particle size ratio, the bulk density and tapped density of the powder are improved. The green body density of the 3D printing graphite material prepared with this powder is relatively high; at the same time, the spherical shaping powder process has high production efficiency, simple and controllable preparation process, and is easy to achieve low-cost production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a preparation process for powder for 3D printing graphite material according to the present invention; Figure 2 It is a schematic structural diagram of a raw material treatment process for powder for 3D printing graphite material according to the present invention; Figure 3 It is a schematic structural diagram of a batching and kneading process for powder for 3D printing graphite material according to the present invention; Figure 4 It is a schematic structural diagram of a powder preparation process for powder for 3D printing graphite material according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, in combination with the accompanying drawings in the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to Figures 1-4 , the present invention provides a preparation process and production method for powders of 3D printing graphite materials, which are carried out according to the following steps; S1. Raw material treatment process; S2. Batching and kneading process; S3. Powder preparation process.

[0020] Furthermore, the S1 raw material treatment process is carried out according to the following steps: C1. Calcined petroleum coke, calcined pitch coke, artificial graphite, and natural graphite are crushed, and then crushed by a jet mill; C2. The above crushed materials are ball milled and shaped by a ball mill. After ball milling, the surface of the powder particles is smoother, preparing for subsequent coating; C3. The ball milled powder is classified by particle size. The powder is classified, and the coarser raw materials continue to enter the ball mill for ball milling. The above process is repeated; C4. High-temperature pitch is selected, dried and then crushed by a crusher, and crushed by a jet mill.

[0021] Specifically, 1. Calcined petroleum coke, calcined pitch coke, artificial graphite, and natural graphite are crushed to about 2 mm, and then crushed by a jet mill to a particle size D50 between 10 - 20 μm; 2. The above crushed materials are ball milled and shaped by a ball mill. The ball milling time is 20 - 30 h. After ball milling, the surface of the powder particles is smoother, preparing for subsequent coating.

[0022] 3. The ball milled powder is classified by particle size. The powder with D50 between 3 - 8 μm is classified. The coarser raw materials continue to enter the ball mill for ball milling. The above process is repeated until the average particle size of the powder is between 3 - 8 microns.

[0023] 4. High-temperature pitch with a softening point of 200 - 250 °C is selected, dried at 100 °C and then crushed to less than 2 mm by a crusher, and crushed by a jet mill. The crushing particle size D50 is between 1 - 3 μm.

[0024] Furthermore, the S2 batching and kneading process is carried out according to the following steps: A1. Mix the above graded raw materials in different proportions; A2. Add the prepared materials above into a high-speed VC mixer and mix them. Put the mixed materials into a high-temperature mixer and knead them at high temperature. Nitrogen should be continuously introduced during the kneading process. The kneaded paste should be quickly rolled into sheets.

[0025] Specifically, 1. The above graded raw materials are batched in different proportions, and the batching proportions are as follows: The main proportions of this process are as follows: Note: One or more of the above raw materials can be selected and mixed, and the formula is only adjusted according to the performance of the subsequent products. The preparation process of the powder is the same, so they should all fall within the scope of this patent.

[0026] 2. Add the above prepared materials into a high-speed VC mixer and mix for 2 hours at a speed of 400-500r / min and a mixing temperature of 40-60°C. Put the mixed materials into a high-temperature mixer and knead them at a temperature of 280-320°C for 2 hours. During the kneading process, nitrogen should be continuously introduced at a flow rate of 5-8L / min. The kneaded paste should be quickly rolled into sheets with a sheet thickness of 1-2mm and a volatile matter of 13-15%.

[0027] Furthermore, the S3 powder preparation process is carried out according to the following steps: B1. Crushing the prepared tablets using an impact jet mill; B2. Mechanically shaping the above powders; B3. The shaped powder is subjected to airflow classification, and the airflow classification adopts three-level classification. B4. Grading and compounding: B5. Powder mixing: Use a high-speed mixer to mix the above proportions; B6. After uniform mixing, powders of different proportions can be used to meet different printing requirements.

[0028] Specifically, 1. The prepared tablets are crushed to about 2 mm, and then crushed to a particle size of 30-300 μm using an impact jet mill.

[0029] 2. The above powders are mechanically shaped. The shaping parameters and particle size control range are as follows: 3. The shaped powder is subjected to airflow classification. The airflow classification adopts three-level classification, and the above powder is classified into the following particle size intervals: 4. Hierarchical compounding. The above powder materials are compounded according to the following principles: 5. Powder mixing. Use a high-speed mixer to mix the above proportions. The mixing speed is 500 - 800 r / min, the mixing temperature is 50 - 80 °C, and the mixing time is 1 h.

[0030] 6. After uniform mixing, the bulk density of the powder is 0.80 - 0.90 g / cm3, and the tapped density is 1.00 - 1.10 g / cm3.

[0031] Powders with different proportions can be used to meet different printing requirements Furthermore, a production method of a powder material for 3D printing graphite materials is carried out according to the following steps; D1. Print the uniformly mixed powder through a specific 3D printing device. During the printing process, the performance of the printed parts can be precisely controlled by adjusting the proportion of the powder and printing parameters such as layer thickness and printing speed.

[0032] Furthermore, the main proportions in A1 are as follows: 60% calcined petroleum coke and 40% high-temperature pitch; 60% calcined pitch coke and 40% high-temperature pitch; 60% artificial graphite and 40% high-temperature pitch; 60% natural graphite and 40% high-temperature pitch.

[0033] Furthermore, in B2, the shaping parameters and particle size control ranges are as follows: Shaping times 1: Feed particle size range: 30 - 300 μm, discharge particle size range: 30 - 280 μm; Shaping times 2: Feed particle size range: 30 - 280 μm, discharge particle size range: 32 - 240 μm; Shaping times 3: Feed particle size range: 32 - 240 μm, discharge particle size range: 35 - 210 μm; Shaping times 4: Feed particle size range: 35 - 210 μm, discharge particle size range: 40 - 180 μm.

[0034] Furthermore, in B3, air classification is carried out in three stages, and the above powder materials are classified into the following particle size ranges: Powder 1: First-stage classification, discharge particle size range: 150 - 180 μm; Powder 2: Second-stage classification, discharge particle size range: 100 - 150 μm; Powder 3: First-stage classification, discharge particle size range: 50 - 100 μm.

[0035] 9. A preparation process and production method for powder materials used in 3D printing of graphite materials, characterized in that for the classification and compounding in B4, the above powder materials are compounded according to the following principles: Ratio 1: Powder material 1: 20%; Powder material 2: 30%; Powder material 3: 50%; Ratio 1: Powder material 1: 30%; Powder material 2: 30%; Powder material 3: 40%; Ratio 1: Powder material 1: 40%; Powder material 2: 30%; Powder material 3: 30%.

[0036] Working principle: Example 1: Calcined petroleum coke / pitch coke powder is used. After 4 times of shaping, the particle size range is 30 - 200 μm. The classification particle size range and compounding method are as follows: The high-speed mixer mixes the above ratios at a mixing speed of 600 r / min, a mixing temperature of 60 °C, and a mixing time of 1 h. After uniform mixing, the bulk density of the powder is 0.78 g / cm3, and the tapped density is 0.90 g / cm3. The bulk density is relatively low.

[0037] Example 2: Calcined petroleum coke / pitch coke powder is used. After 4 times of shaping, the particle size range is 30 - 200 μm. The classification particle size range and compounding method are as follows: The high-speed mixer mixes the above ratios at a mixing speed of 500 r / min, a mixing temperature of 60 °C, and a mixing time of 1 h. After uniform mixing, the bulk density of the powder is 0.82 g / cm3, and the tapped density is 1.02 g / cm3. The bulk density is better.

[0038] Example 3: Artificial graphite / natural graphite is used. After shaping, the particle size range is 30 - 200 μm. The classification particle size range and compounding method are as follows: The high-speed mixer mixes the above ratios at a mixing speed of 600 r / min, a mixing temperature of 80 °C, and a mixing time of 1 h. After uniform mixing, the bulk density of the powder is 0.81 g / cm3, and the tapped density is 1.00 g / cm3. The bulk density is relatively low.

[0039] Example 4: Artificial graphite / natural graphite is used. After shaping, the particle size range is 50 - 200 μm. The classification particle size range and compounding method are as follows: The high-speed mixer mixes the above ratios at a mixing speed of 500 r / min, a mixing temperature of 80 °C, and a mixing time of 1 h. After uniform mixing, the bulk density of the powder is 0.86 g / cm3, and the tapped density is 1.07 g / cm3. The bulk density is relatively high.

[0040] Example 5: Artificial graphite / natural graphite is used, and the particle size range after shaping is 50 - 150 μm. The classification particle size range and compounding method are as follows: The above proportions are mixed by a high-speed mixer at a mixing speed of 500 r / min, a mixing temperature of 50 °C, and a mixing time of 1 h. After uniform mixing, the bulk density of the powder is 0.85 g / cm3, and the tapped density is 1.08 g / cm3. The bulk density is relatively high.

[0041] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing powder of graphite material for 3D printing, comprising the following steps: S1, raw material processing technology; S2, ingredient mixing and kneading process; S3. Powder preparation process.

2. A process for preparing a powder of graphite material for 3D printing according to claim 1, characterized in that: The S1 raw material processing process is carried out according to the following steps: C1. Crush calcined petroleum coke, calcined asphalt coke, artificial graphite and natural graphite, and then crush them with a jet mill; C2. The above crushed materials are ball-milled and shaped. After ball milling, the surface of the powder particles is smoother, preparing for subsequent coating; C3, the milled powder is graded, the graded powder is discharged, the coarser raw materials continue to enter the ball mill for ball milling, and the above process is repeated; C4. Select high-temperature asphalt, dry it, and crush it with a crusher or a jet mill.

3. The process for preparing a powder of graphite material for 3D printing according to claim 1, characterized in that: The S2 batching and kneading process is carried out according to the following steps: A1. Mix the above graded raw materials in different proportions; A2. Add the prepared materials above into a high-speed VC mixer and mix them. Put the mixed materials into a high-temperature mixer and knead them at high temperature. Nitrogen should be continuously introduced during the kneading process. The kneaded paste should be quickly rolled into sheets.

4. The process for preparing a powder of graphite material for 3D printing according to claim 1, characterized in that: The S3 powder preparation process is carried out according to the following steps: B1. Crushing the prepared tablets using an impact jet mill; B2. Mechanically shaping the above powders; B3. The shaped powder is subjected to airflow classification, and the airflow classification adopts three-level classification. B4. Grading and compounding: B5. Powder mixing: Use a high-speed mixer to mix the above proportions; B6. After uniform mixing, powders of different proportions can be used to meet different printing requirements.

5. A method for producing powder of graphite material for 3D printing, comprising the following steps: D1. The evenly mixed powder is printed through a specific 3D printing device. During the printing process, the performance of the printed part can be precisely controlled by adjusting the powder ratio and printing parameters, such as layer thickness and printing speed.

6. The process for preparing a powder of graphite material for 3D printing according to claim 2, characterized in that: The main proportions of A1 are as follows: 60% calcined petroleum coke, 40% high-temperature asphalt; 60% calcined asphalt coke, 40% high-temperature asphalt; 60% artificial graphite, 40% high-temperature asphalt; 60% natural graphite, 40% high-temperature asphalt.

7. The preparation process and production method of a powder for 3D printing graphite material according to claim 1, characterized in that: In B2, the shaping parameters and granularity control range are as follows: Shaping times 1: Feeding size range: 30-300μm, discharging size range: 30-280μm; Shaping times 2: feed particle size range: 30-280μm, discharge particle size range: 32-240μm; Shaping times 3: feed particle size range: 32-240μm, discharge particle size range: 35-210μm; Shaping times 4: Feed size range: 35-210μm, discharge size range: 40-180μm.

8. The preparation process and production method of a powder for 3D printing graphite material according to claim 1, characterized in that: The airflow classification in B3 adopts three-level classification, and the powder is classified into the following particle size intervals: Powder 1: primary classification, discharge particle size range: 150-180μm; Powder 2: Secondary classification, particle size range: 100-150μm; Powder 3: primary classification, discharge particle size range: 50-100μm.

9. The preparation process and production method of a powder for 3D printing graphite material according to claim 1, characterized in that: The graded compounding in B4 is to compound the above powders according to the following principles: Ratio 1: Powder 1: 20%; Powder 2: 30%: Powder 3: 50%; Ratio 1: Powder 1: 30%; Powder 2: 30%: Powder 3: 40%; Ratio 1: Powder 1: 40%; Powder 2: 30%: Powder 3: 30%.

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