Silicon carbide particles for photocuring 3D printing and preparation method and application thereof

Abstract

The application belongs to the technical field of 3D printing, and particularly relates to a kind of silicon carbide particles for photocuring 3D printing and a preparation method and application thereof. In order to obtain spherical silicon carbide primary powder and improve its bulk density, the application provides a preparation method of silicon carbide particles for photocuring 3D printing, which comprises: mixing silicon carbide powder and etching liquid, first heating at 50-70 DEG C for 1-5 minutes, then centrifuging, washing and drying to obtain the silicon carbide particles for photocuring 3D printing. The method of the application can eliminate the sharp corners of the powder by immersing the silicon carbide primary powder in the etching liquid, so that the shape of the silicon carbide particles gradually becomes spherical, and the sphericity of the prepared silicon carbide can reach more than 0.8.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing technology, specifically relating to a photopolymerizable silicon carbide particle for 3D printing, its preparation method, and its application. Background Technology

[0002] Silicon carbide (SiC) ceramics possess excellent properties such as strong oxidation resistance, good wear resistance, high hardness, good thermal stability, high high-temperature strength, low coefficient of thermal expansion, high thermal conductivity, and resistance to thermal shock and chemical corrosion. Therefore, they have been increasingly valued and applied in fields such as petroleum, chemical, machinery, aerospace, and nuclear energy. For example, SiC ceramics can be used as various bearings, ball bearings, nozzles, seals, cutting tools, gas turbine blades, turbocharger rotors, reflectors, and rocket combustion chamber liners, among others.

[0003] Due to the high brittleness and exceptionally high hardness of silicon carbide ceramics, the powder materials prepared from them are generally irregular particles, or even flakes, with very few spherical silicon carbide powders. Figure 1 This is a scanning electron microscope (SEM) image of the silicon carbide powder raw material used in this experiment. The image shows that the silicon carbide powder particles have very irregular shapes with prominent edges. If the primary silicon carbide particles constituting the powder have low sphericity (a shape with many corners on the particle surface) instead of high sphericity (a shape with fewer corners on the particle surface), this will result in a low relative bulk density, leading to severe thickening when added to dissimilar liquid materials such as resins. The relative density of the structural material has a significant impact on molding performance and also determines the porosity of the preform.

[0004] Currently, the preparation method for silicon carbide powder involves first manufacturing large silicon carbide particles using an Atcheson furnace, and then pulverizing them into powder. Therefore, the primary silicon carbide particles obtained by this method have low sphericity, are irregular in shape, and have prominent edges. Known methods for removing the corners from the surface of primary silicon carbide particles with low sphericity to create particles with high sphericity include grinding methods using mortars and pestles, and particle impact methods using jet mills.

[0005] However, silicon carbide has high hardness, so mechanical processing methods such as grinding and particle impaction are inefficient and difficult to fully remove the corners from the surface of primary silicon carbide particles to form a spherical shape, resulting in poor processing effects. Furthermore, these mechanical processing methods negatively impact the particle size distribution of silicon carbide powder, affecting sintering performance. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a method for preparing a spherical silicon carbide primary powder, which improves its bulk density, and which does not easily cause thickening even when added to liquid dissimilar materials such as photosensitive resins.

[0007] On the one hand, the present invention provides a method for preparing silicon carbide particles for photopolymerization 3D printing, comprising: mixing silicon carbide powder and etching solution, heating and reacting at 50-70°C for 1-5 minutes, and then centrifuging, washing and drying to obtain the silicon carbide particles for photopolymerization 3D printing;

[0008] Preferably, the corrosive solution is a mixture of hydrofluoric acid and nitric acid;

[0009] Preferably, the ratio of the etching solution to silicon carbide powder is (100-500) mL: 100 g.

[0010] The method of this invention eliminates the sharp corners of the powder by immersing silicon carbide raw powder in an etching solution, making the silicon carbide particles gradually become spherical, and the sphericity of the prepared silicon carbide can reach more than 0.8.

[0011] Preferably, the particle size of the silicon carbide powder is 0.1–150 μm. A method for preparing photopolymerizable silicon carbide particles for 3D printing using chemical etching involves etching ordinary SiC powder with a mixture of hydrofluoric acid and nitric acid, wherein the powder size is preferably on the order of micrometers.

[0012] Preferably, the corrosive solution is obtained by mixing hydrofluoric acid and nitric acid; the concentration of the hydrofluoric acid is 35% to 45% (mass fraction); the concentration of the nitric acid is 60% to 70% (mass fraction); preferably, the volume ratio of the hydrofluoric acid to the nitric acid is (1 to 3): 1, more preferably (2 to 3): 1.

[0013] Furthermore, preferably, the method for preparing the etching solution is as follows: first add concentrated hydrofluoric acid, then add concentrated nitric acid, stir evenly, seal and let stand for 10 to 30 minutes to obtain the etching solution.

[0014] Preferably, the centrifugation parameters include: a rotation speed of 6000–20000 rpm and a time of 1–5 min;

[0015] The washing parameters include: washing at least twice with distilled water as the washing solution in a constant temperature water bath of 40-70°C until the pH of the washing solution is neutral.

[0016] The drying temperature is 60–80°C, and the time is 6–12 hours;

[0017] Preferably, after drying, the material is sieved; the sieving parameter is 100 mesh.

[0018] On the other hand, the present invention provides photocurable silicon carbide particles for 3D printing prepared according to the above preparation method, wherein the particle size of the photocurable silicon carbide particles for 3D printing is 0.1 to 150 μm.

[0019] In another aspect, the present invention provides a photocurable silicon carbide ceramic slurry for 3D printing, comprising: silicon carbide particles and photosensitive resin; preferably, the photosensitive resin comprises one or more of 1,6-hexanediol diacrylate (HDDA), trimethylolpropane triacrylate (TMPTA), and polyethylene glycol diacrylate (PEGDA).

[0020] Preferably, the silicon carbide ceramic slurry has a solid content of 40-60 vol% and a viscosity of 0.01-8 Pa·s.

[0021] The silicon carbide obtained in this invention has a sphericity of over 0.8, and its addition to photosensitive resin will not cause significant thickening. The ceramic slurry prepared in this way has low viscosity.

[0022] The beneficial effects of this invention are:

[0023] The preparation method of this invention is simple, requires no complicated experimental equipment, the experimental materials are inexpensive and easy to obtain, the sphericity of the prepared silicon carbide can reach more than 0.8, and it will not cause special thickening even when added to resin. The prepared ceramic slurry has low viscosity. Attached Figure Description

[0024] Figure 1 The image shows a TEM image of the silicon carbide raw material used in this invention. As can be seen from the image, the original powder has sharp edges and is mostly polygonal.

[0025] Figure 2 The image shows a TEM image of silicon carbide prepared according to the present invention. It can be seen from the image that the sharp edges of the powder disappear after treatment and the sphericity is improved. Detailed Implementation

[0026] The present invention will be further illustrated by the following embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the present invention.

[0027] The silicon carbide powder obtained in this embodiment is as described above. The primary particle shape of silicon carbide is highly spherical, therefore, it is not easy to cause thickening even when added to liquid photosensitive resin. As a result, the viscosity of the mixture of silicon carbide powder and liquid photosensitive resin in this embodiment is similar to the original viscosity of the liquid dissimilar material, or even if thickening is performed, it is not easy to cause significant thickening.

[0028] Therefore, the silicon carbide powder of this embodiment can be used to prepare ceramic slurries with high solids content. Furthermore, the ceramic slurry formulated with the silicon carbide powder of this embodiment and liquid photosensitive resin exhibits excellent printing performance.

[0029] The following is an exemplary description of a method for preparing silicon carbide particles for photopolymer 3D printing.

[0030] First, add concentrated hydrofluoric acid to the reaction vessel, then slowly add concentrated nitric acid. After stirring evenly, seal and let stand for 10-30 minutes to obtain the etching solution. The acid concentration used for ordinary chemical etching is 35%-45% hydrofluoric acid and 60-70% nitric acid, with a volume ratio of (2.0-3.0):1.0.

[0031] Silicon carbide powder and etching solution are mixed and reacted. The amount of etching solution is 1-5 times that of SiC powder during the reaction, and the mixture is heated to 60°C for 1-5 minutes.

[0032] After the reaction is complete, cool the mixture. After cooling, centrifuge the acid solution and powder together in a high-speed centrifuge, discard the upper acid layer, and collect the lower powder layer.

[0033] Then, wash the solution multiple times with distilled water in a 60°C constant temperature water bath until the pH of the washing solution is neutral.

[0034] Finally, dry in an oven at 60-80℃ for 6-12 hours. The final product is photocurable silicon carbide particles for 3D printing. Preferably, after drying, pass through a 100-mesh sieve.

[0035] The main feature of the silicon carbide powder of the present invention is that it is a silicon carbide powder with an α-type crystal system, and the sphericity of the primary silicon carbide particles constituting the silicon carbide powder is 0.8 or higher.

[0036] In this invention, the sphericity of powder particles can be characterized by the actual surface area of ​​the particle and the surface area of ​​a sphere of equal volume. This is mainly because, for particles of equal volume, spherical particles have the smallest surface area. The calculation formula is as follows:

[0037] In the formula, η represents the sphericity of the powder particles; d 3，2 : Average diameter of surface area; d 4，3 : Volume average diameter.

[0038] The following examples further illustrate the present invention in detail. It should also be understood that the following examples are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0039] Example 1

[0040] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 3:1. For preparation, 100g of SiC powder (5μm particle size) was weighed and added to 500mL of the etching solution. The mixture was heated to 60℃ in a constant temperature bath for 3 minutes. After cooling, the acid solution and powder were centrifuged together in a high-speed centrifuge. The upper acid layer was discarded, and the lower powder layer was collected. The powder was then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution was neutral. The powder was then dried in a 60℃ oven for 12 hours and passed through a 100-mesh sieve to obtain the photocurable silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.92. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 0.8 Pa·s (shear rate of 10 s⁻¹). -1 ).

[0041] Example 2

[0042] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 2:1. For preparation, 100g of SiC powder (5μm particle size) is weighed and added to 500mL of the etching solution. The mixture is heated to 60℃ in a constant temperature bath for 2 minutes. After cooling, the acid solution and powder are centrifuged together in a high-speed centrifuge. The upper acid layer is discarded, and the lower powder layer is collected. The powder is then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution is neutral. The powder is then dried in a 60℃ oven for 12 hours, and finally passed through a 100-mesh sieve to obtain the photocurable silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.88. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of the treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 1.4 Pa·s (shear rate 10 s⁻¹). -1 ).

[0043] Example 3

[0044] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 2:1. For preparation, 100g of SiC powder (5μm particle size) is weighed and added to 500mL of the etching solution. The mixture is heated to 60℃ in a constant temperature bath for 1 minute. After cooling, the acid solution and powder are centrifuged together in a high-speed centrifuge. The upper acid layer is discarded, and the lower powder layer is collected. The powder is then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution is neutral. The powder is then dried in a 60℃ oven for 12 hours, and finally passed through a 100-mesh sieve to obtain the photocurable silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.85. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of the treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 3.2 Pa·s (shear rate 10 s⁻¹). -1 ).

[0045] Example 4

[0046] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 2:1. For preparation, 100g of SiC powder (5μm particle size) is weighed and added to 100mL of the etching solution. The mixture is heated to 60℃ in a constant temperature bath for 1 minute. After cooling, the acid solution and powder are centrifuged together in a high-speed centrifuge. The upper acid layer is discarded, and the lower powder layer is collected. The powder is then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution is neutral. The powder is then dried in a 60℃ oven for 12 hours, and finally passed through a 100-mesh sieve to obtain the photocurable silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.81. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of the treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 5.6 Pa·s (shear rate 10 s⁻¹). -1 ).

[0047] Example 5

[0048] The preparation process of silicon carbide particles in Example 5 is the same as in Example 1, except that the temperature is increased to 60°C in a constant temperature bath and the reaction time is 1 min.

[0049] Example 6

[0050] The preparation process of silicon carbide particles in Example 6 is the same as in Example 1, except that the temperature is increased to 60°C in a constant temperature bath and the reaction time is 3 minutes.

[0051] Example 7

[0052] The preparation process of silicon carbide particles in Example 7 is the same as in Example 1, except that the temperature is increased to 60°C in a constant temperature bath and the reaction time is 7 minutes.

[0053] Example 8

[0054] The preparation process of silicon carbide particles in Example 8 is the same as in Example 1, except that 100g of SiC powder (particle size of 5μm) was weighed and added to 100mL of the above etching solution.

[0055] Example 9

[0056] The preparation process of silicon carbide particles in Example 9 is the same as in Example 1, except that 100g of SiC powder (particle size of 5μm) was weighed and added to 200mL of the above etching solution.

[0057] Example 10

[0058] The preparation process of silicon carbide particles in Example 10 is the same as in Example 1, except that: 100g of SiC powder (particle size of 5μm) was weighed and added to 300mL of the above etching solution.

[0059] Comparative Example 1

[0060] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 3:1. For preparation, 100g of SiC powder (5μm particle size) is weighed and added to 600mL of the etching solution. The mixture is heated to 60℃ in a constant temperature bath for 3 minutes. After cooling, the acid solution and powder are centrifuged together in a high-speed centrifuge. The upper acid layer is discarded, and the lower powder layer is collected. The powder is then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution is neutral. The powder is then dried in a 60℃ oven for 12 hours, and finally passed through a 100-mesh sieve to obtain the photocurable silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.75. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of the treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 12.3 Pa·s (shear rate 10 s⁻¹). -1 ).

[0061] Comparative Example 2

[0062] The acid used in conventional chemical etching is 40% hydrofluoric acid and 65% nitric acid in a volume ratio of 3:1. For preparation, 100g of SiC powder (5μm particle size) was weighed and added to 500mL of the etching solution. The mixture was heated to 60℃ in a constant temperature bath for 10 minutes. After cooling, the acid solution and powder were centrifuged together in a high-speed centrifuge. The upper acid layer was discarded, and the lower powder layer was collected. The powder was then washed repeatedly with distilled water in a 60℃ constant temperature water bath until the pH of the washing solution was neutral. The powder was then dried in a 60℃ oven for 12 hours and passed through a 100-mesh sieve to obtain the photocured silicon carbide particles for 3D printing. The sphericity of the obtained particles was 0.72, and the particle size decreased significantly. 27.5 mL of HDDA, 27.5 mL of TMPTA, 1.18 g of BAPO, and 145.35 g of treated silicon carbide particles were placed in a beaker and mechanically stirred for 30 min to obtain a ceramic slurry with a solid content of 45 vol.%. The viscosity of the obtained ceramic slurry was 42 Pa·s (shear rate of 10 s⁻¹). -1 ).

[0063] Comparative Example 3

[0064] Weigh 100g of SiC powder (particle size 5μm) and directly prepare a slurry with a solid content of 45 vol.%.

[0065] Table 1 shows the preparation parameters and performance parameters of silicon carbide particles and silicon carbide slurry:

[0066]

[0067]

Claims

1. A method for preparing silicon carbide particles for photopolymerization 3D printing, characterized in that, include: Silicon carbide powder and etching solution are mixed and heated at 50-70°C for 1-5 minutes. After centrifugation, washing and drying, the resulting photocurable silicon carbide particles for 3D printing with a sphericity ≥0.8 are obtained. The particle size of the silicon carbide powder is 0.1-150 μm. The particle size of the photocurable silicon carbide particles for 3D printing is 0.1-150 μm. The corrosive solution is a mixture of hydrofluoric acid and nitric acid; The ratio of the etching solution to silicon carbide powder is (100-500) mL: 100 g.

2. The preparation method according to claim 1, characterized in that, The concentration of the hydrofluoric acid is 35wt% to 45wt%; the concentration of the nitric acid is 60wt% to 70wt%.

3. The preparation method according to claim 1, characterized in that, The volume ratio of hydrofluoric acid to nitric acid is (1-3):

1.

4. The preparation method according to claim 1, characterized in that, The method for preparing the corrosion solution is as follows: first add concentrated hydrofluoric acid, then add concentrated nitric acid, stir evenly, seal and let stand for 10 to 30 minutes to obtain the corrosion solution.

5. The preparation method according to any one of claims 1-4, characterized in that, The centrifugation parameters include: a rotation speed of 6000–20000 rpm and a time of 1–5 min; The washing parameters include: washing at least twice with distilled water as the washing solution in a constant temperature water bath of 40-70°C until the pH of the washing solution is neutral. The drying temperature is 60–80°C, and the time is 6–12 hours.

6. The preparation method according to any one of claims 1-4, characterized in that, After drying, the product is sieved; the sieving parameter is 100 mesh.

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