CN112723890B - A kind of photocurable ceramic slurry and preparation method of silicon carbide ceramics - Google Patents

Abstract

The application provides a photocurable ceramic slurry, comprising the following raw materials by mass percentage: SiC@SiO ₂ powder: 25%-60%; photocurable resin: 10%-40%; carbon source resin: 10% ‑40%; Photoinitiator: 0.1%‑2%; Dispersant: 2%‑6%; wherein, the SiC@SiO ₂ powder includes a SiC core and a SiO ₂ shell coated on the surface of the SiC core; a carbon source The residual carbon rate of the resin at 800°C is greater than or equal to 40%. The SiO ₂ shell layer can react with the carbon source resin to generate secondary phase SiC during the sintering process while improving the forming efficiency of the photocurable ceramic slurry, thereby reducing/eliminating the introduced SiO ₂ shell layer. Through the reaction sintering process, the rapid manufacture of complex and fine SiC ceramic parts is realized. The present application also provides a preparation method of silicon carbide ceramics.

Description

A kind of preparation method of photocurable ceramic slurry and silicon carbide ceramics

technical field

The present application relates to the technical field of ceramic additive manufacturing, in particular to a preparation method of a photocurable ceramic slurry and a silicon carbide ceramic.

Background technique

Silicon carbide ceramics have the advantages of stable chemical properties, good wear resistance, high hardness, high mechanical strength and chemical corrosion resistance, and are widely used in aerospace, semiconductor and nuclear industries. Compared with the traditional ceramic preparation process, light-cured ceramic molding has the advantages of high molding precision, short molding cycle and simple process. However, due to the strong absorption of ultraviolet light by silicon carbide and the large difference in refractive index between silicon carbide and photocurable resin, the photocuring molding efficiency of silicon carbide ceramic slurry is low. Therefore, it is necessary to provide a photocurable ceramic paste to solve the problem of poor photocuring performance of the existing silicon carbide ceramic paste.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present application provides a photocuring ceramic slurry, the photocuring ceramic slurry has good photocuring molding efficiency, effectively shortens the photocuring molding time of silicon carbide ceramics, and the prepared silicon carbide ceramics With high strength, high density and high precision, it can realize the rapid manufacture of complex and fine SiC ceramic parts. The present application also provides a preparation method of silicon carbide ceramics.

A first aspect of the present application provides a photocurable ceramic slurry, comprising the following raw materials by mass percentage:

SiC@SiO ₂ powder: 25%-60%;

Light curing resin: 10%-40%;

Carbon source resin: 10%-40%;

Photoinitiator: 0.1%-2%;

Dispersant: 2%-6%;

The SiC@SiO ₂ powder includes a SiC core body and a SiO ₂ shell layer coated on the surface of the SiC core body; the carbon residual rate of the carbon source resin at 800° C. is greater than or equal to 40%.

In the present application, the absorption of ultraviolet light by SiC is reduced by coating the SiC surface with a SiO ₂ shell layer, and the formed SiC@SiO ₂ powder has a lower refractive index, thereby effectively improving the transmission depth of ultraviolet light in the ceramic slurry , reduces the critical exposure energy of the ceramic slurry, increases the curing thickness of the ceramic slurry per unit time, improves the photo-curing efficiency, and ensures that the prepared silicon carbide ceramic has high precision; the role of the photo-curable resin in the photo-initiator Under UV light irradiation, the photocuring of silicon carbide ceramics can be achieved; since the introduction of SiO ₂ will reduce the high temperature resistance of silicon carbide ceramics, adding a certain content of carbon source resin can eliminate SiO ₂ , and the carbon source resin has high residual carbon During the sintering process of ceramics, the carbon formed by the pyrolysis of carbon source resin can react with _SiO2 to generate SiC, thereby improving the high temperature resistance of silicon carbide ceramics. The dispersant can promote the uniform dispersion of SiC@SiO ₂ powder in the slurry, inhibit powder agglomeration, increase the solid content of the slurry, and reduce the shrinkage rate of ceramic sintering.

Optionally, the particle size of the SiC core body is 0.1 μm-30 μm. Further, the particle size of the SiC core body is 3 μm-20 μm.

Optionally, the thickness of the SiO ₂ shell layer is 20nm-2000nm. Further, the thickness of the SiO ₂ shell layer is 30nm-1000nm.

Optionally, the SiC@SiO ₂ powder includes a first SiC@SiO ₂ powder and a second SiC@SiO ₂ powder; the particle size of the first SiC@SiO ₂ powder is greater than 0.1 μm and less than or equal to 5 μm; The particle size of the second SiC@SiO ₂ powder is greater than 5 μm and less than or equal to 32 μm.

Optionally, the volume ratio of the second SiC@SiO ₂ powder to the first SiC@SiO ₂ powder is greater than 0 and less than or equal to 1.

Optionally, the SiC@SiO ₂ powder is prepared by a high-temperature oxidation method; the high-temperature oxidation method includes: keeping the SiC powder at 800° C.-1200° C. for 1 h-20 h to obtain a crude SiC@SiO ₂ powder. The crude SiC@SiO ₂ powder is post-treated to obtain SiC@SiO ₂ powder.

Optionally, the heating rate of the high temperature oxidation method is 1°C/min-5°C/min.

Optionally, the post-processing includes crushing and sieving.

Optionally, the crushing includes grinding, and the grinding includes wet ball milling.

Optionally, the material-to-ball ratio of the wet ball mill is 1:(2-4).

Optionally, the ball milling time of the wet ball milling is 12h-48h.

Optionally, the solvent of the wet ball milling includes ethanol, and the volume ratio of the ethanol to the crude SiC@SiO ₂ powder is 1:(1-19).

Optionally, the wet ball milling further includes adding a silane coupling agent, and the mass ratio of the crude SiC@SiO ₂ powder to the silane coupling agent is 1:(0.005-0.1).

Optionally, the carbon source resin includes phenolic resin.

Optionally, the carbon source resin includes one or more of novolac epoxy acrylate and benzoxazine.

Optionally, the photocurable resin includes one or more of trimethylolpropane triacrylic acid, 1,6-hexanediol diacrylate and polydihexaacrylate.

Optionally, the photoinitiator includes diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,2-dimethoxy-2-phenylacetophenone, 2-iso One or more of propylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexyl phenyl ketone.

Optionally, the dispersant includes one or more of acrylate-type dispersants, polyurethane-type dispersants and polyester-type dispersants.

Optionally, the viscosity of the photocurable ceramic slurry is 1 Pa·s-5 Pa·s.

A second aspect of the present application provides a method for preparing silicon carbide ceramics, comprising the following steps:

The photo-cured ceramic slurry is photo-cured to obtain a SiC@SiO ₂ ceramic body; the photo-cured ceramic slurry includes the following raw materials by mass percentage:

SiC@SiO ₂ powder: 25%-60%;

Light curing resin: 10%-40%;

Carbon source resin: 10%-40%;

Photoinitiator: 0.1%-2%;

Dispersant: 2%-6%;

The SiC@SiO ₂ powder includes a SiC core body and a SiO ₂ shell layer coated on the surface of the SiC core body; the carbon residual rate of the carbon source resin at 800° C. is greater than or equal to 40%;

The SiC@SiO ₂ ceramic body is heated by programmed temperature to carbonize the carbon source resin, and then kept at 1000° C.-1700° C. for 2h-8h to carbonize SiO ₂ to form SiC to obtain silicon carbide ceramics.

Optionally, the conditions for the temperature program are: heating to 150°C-220°C at a heating rate not higher than 3°C/min, and holding for 1-3h; heating up to 250°C at a heating rate not higher than 3°C/min. ℃-380℃, hold for 1-3h; raise the temperature to 700℃-900℃ at a heating rate not higher than 3℃/min, and hold for 1-3h.

Optionally, the preparation method further includes: mixing the SiC ceramics with silicon particles, and keeping the temperature at 1500°C-1650°C for 10min-60min to obtain densified silicon carbide ceramics.

Optionally, the equipment used for the photocuring molding includes any one of a stereo photocuring molding machine and a digital light processing molding machine.

Optionally, when a stereo light curing molding machine is used for light curing molding, the laser power of the stereo light curing molding machine is 0.1w-3w, the scanning speed of the stereo light curing molding machine is 1000mm/s-4000mm/s, and the stereo light curing machine is 1000mm/s-4000mm/s. The layer thickness of the molding machine is 10μm-150μm.

Optionally, when a digital light processing molding machine is used for light curing molding, the laser power of the digital light processing molding machine is 7mw/cm2-100mw/cm2, the exposure time of the digital light processing molding machine is 1s-90s, and the digital light processing molding machine is 1s-90s. The layer thickness of the machine is 10μm-150μm.

The preparation method of silicon carbide ceramics provided in the second aspect of the present application is easy to operate, simple in process, short in production cycle, and suitable for industrial mass production; silicon carbide ceramics with high precision and complex structure can be prepared by photocuring molding technology, and the obtained silicon carbide ceramics Ceramics have high density and good high temperature resistance, and have good application prospects.

Description of drawings

1 is a process flow diagram of a preparation process of a photocurable ceramic slurry provided by an embodiment of the application;

FIG. 2 is a process flow diagram of the preparation of silicon carbide ceramics provided by an embodiment of the application;

3 is a scanning electron microscope image of the SiC@SiO powder prepared in Example ₁ of the application;

4 is a scanning electron microscope image of the SiC@SiO powder prepared in Example ₂ of the application;

5 is a comparison diagram of the photocuring efficiency test of the photocurable ceramic pastes of Examples 1-2 and Comparative Example 1 of the present application;

FIG. 6 is a comparison diagram of the curing thickness of the photocurable ceramic paste of Example 1 and Comparative Example 1 under the exposure time of 90s, in which, (a) in FIG. 6 is the photocurable ceramic paste of Comparative Example 1 under the exposure time of 90s Cured thickness diagram, Figure 6(b) is the cured thickness diagram of the photocurable ceramic slurry of Example 1 under 90s exposure time;

FIG. 7 is a photo-curing printing effect diagram of the photo-curing ceramic paste in Example 1 of the application, wherein (a) in FIG. 7 is a three-dimensional model diagram of the ceramic part in Example 4, and (b) in FIG. Photograph of the SiC@ _SiO2 ceramic body.

Detailed ways

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

The application provides a photocurable ceramic slurry, comprising the following raw materials by mass percentage:

SiC@SiO ₂ powder: 25%-60%;

Light curing resin: 10%-40%;

Carbon source resin: 10%-40%;

Photoinitiator: 0.1%-2%;

Dispersant: 2%-6%.

In the embodiment of the present application, the SiC@SiO ₂ powder includes a SiC core body and a SiO ₂ shell layer coated on the surface of the SiC core body. SiO ₂ has a low refractive index. When SiO ₂ is coated on the surface of SiC, it can effectively reduce the absorption of ultraviolet light by SiC and the refractive index difference between it and the photocurable resin, and improve the absorption of ultraviolet light in the paste. The transmission depth and the curing thickness of the ceramic layer per unit time can reduce the critical exposure energy and improve the photocuring performance of the photocurable ceramic paste, which is beneficial to the preparation of silicon carbide ceramics with high structural precision and high density.

In the embodiment of the present application, the particle size of the SiC core is 0.1 μm to 30 μm. The particle size of the SiC core body may specifically be, but not limited to, 0.1 μm, 0.5 μm, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 15 μm or 30 μm. In the embodiment of the present application, the thickness of the SiO ₂ shell layer is 20 nm-2000 nm. The thickness of the SiO ₂ shell layer may specifically be, but not limited to, 20 nm, 30 nm, 50 nm, 70 nm, 100 nm, 200 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1500 nm or 2000 nm. In the embodiment of the present application, the ratio of the particle size of the SiC core to the thickness of the SiO ₂ shell is 1:(0.01-0.5). In some embodiments of the present application, the ratio of the particle size of the SiC core to the thickness of the SiO ₂ shell is 1:0.15. Controlling the ratio of the particle size of the SiC core to the thickness of the SiO ₂ shell within the above range can ensure that SiO ₂ fully coats the SiC core, thereby effectively reducing the absorption of ultraviolet light by SiC and the refractive index between SiC and the photocurable resin. The difference; and SiO ₂ will not affect the content of SiC in the slurry too much, ensuring that the silicon carbide ceramic has high hardness and high temperature resistance.

In the embodiment of the present application, the particle size of the SiC@SiO ₂ powder is 0.1 μm-32 μm. In some embodiments of the present application, the SiC@SiO ₂ powder includes a first SiC@SiO ₂ powder and a second SiC@SiO ₂ powder, wherein the particle size of the first SiC@SiO ₂ powder is greater than 0.1 μm and less than or equal to 5 μm, The particle size of the second SiC@SiO ₂ powder is greater than 5 μm and less than or equal to 32 μm. In the embodiment of the present application, the volume ratio of the second SiC@SiO ₂ powder to the first SiC@SiO ₂ powder is greater than 0 and less than or equal to 1. By grading the SiC@SiO ₂ powder, the small particle size SiC@SiO ₂ powder can be fully filled between the large particle size SiC@SiO ₂ powder, ensuring that the silicon carbide ceramic has a high density; and during sintering In the process, the use of particle grading can reduce the separation zone between grain boundaries and pores and reduce the sintering temperature. The reduction of the sintering temperature can reduce the abnormal growth of grains, ensure the uniform distribution of ceramic grains, and improve the structural strength of silicon carbide ceramics.

In the embodiment of the present application, the mass percentage content of the SiC@SiO ₂ powder in the photocurable ceramic slurry is 25%-60%. The mass percentage content of the SiC@SiO ₂ powder in the photocurable ceramic slurry may specifically be, but not limited to, 25%, 30%, 40%, 50%, 55% or 60%. Controlling the content of SiC@SiO ₂ powder within the above range can ensure that the photocurable ceramic slurry has a certain solid content and the slurry has good fluidity.

In this application, coating SiO ₂ on the surface of SiC will reduce the high temperature resistance of silicon carbide ceramics, and due to the different thermal expansion coefficients of SiC and SiO ₂ , the SiO ₂ layer may be separated from SiC during long-term use, resulting in silicon carbide ceramics. Cracks appear and the structural stability of the ceramic deteriorates. In order to solve the above problems, the present application adds a carbon source resin to the photocurable ceramic slurry, and the carbon source resin has a carbon residual rate at 800° C. greater than or equal to 40%. The carbon source resin can be pyrolyzed to generate carbon during the sintering process of silicon carbide ceramics. The SiO ₂ in the SiC@SiO ₂ powder can react with carbon to generate SiC, thereby eliminating the SiO ₂ introduced by coating SiC and ensuring that the silicon carbide ceramics have good properties. high temperature resistance and structural stability.

In the embodiment of the present application, the mass ratio of the SiC@SiO ₂ powder to the carbon source resin is 1:(0.2-1.6). The mass ratio of the SiC@SiO ₂ powder to the carbon source resin may specifically be, but not limited to, 1:0.2, 1:0.4, 1:0.5, 1:0.8, 1:1, 1:1.3 or 1:1.6. Controlling the mass ratio of the SiC@SiO ₂ powder to the carbon source resin within the above range can ensure that the carbon source resin fully reacts with SiO ₂ , thereby eliminating SiO ₂ in the ceramic body.

In the present application, the use of carbon source resin with high carbon residue rate can also improve the density and structural precision of silicon carbide ceramics. Specifically, the residual carbon rate of the photocurable resin in the photocurable paste is low, and the photocurable resin will generate many pores during pyrolysis, which will cause the ceramic body to shrink. In the present application, adding a carbon source resin to the photocurable paste can Reduce the solidification shrinkage of ceramic slurry during sintering, thereby improving the density and structural accuracy of silicon carbide ceramics. In the embodiment of the present application, the residual carbon rate of the carbon source resin at 800° C. is greater than or equal to 40%. The residual carbon rate of the carbon source resin at 800°C can be greater than or equal to 50%, or greater than or equal to 60%. The higher the residual carbon rate of the carbon source resin, the more conducive to the formation of ceramics with high density and structural accuracy pieces. In some embodiments of the present application, the carbon source resin is a phenolic resin. In some embodiments of the present application, the phenolic resin includes one or more of novolac epoxy acrylate and benzoxazine. In some embodiments of the present application, 2130 type phenolic resin is used as the carbon source resin. In the embodiment of the present application, the mass percentage content of the carbon source resin in the photocurable ceramic slurry is 10%-40%. The mass percentage content of the carbon source resin in the photocurable ceramic slurry may be, but not limited to, 10%, 20%, 30% or 40%.

In the present application, the photoinitiator can generate free radicals and cations under the irradiation of ultraviolet light, thereby catalyzing the polymerization, crosslinking and curing of the photocurable resin, and then curing and molding the silicon carbide ceramic body. In the embodiment of the present application, when the structure of the carbon source resin contains unsaturated functional groups, the photoinitiator can also catalyze the polymerization, crosslinking and curing of the carbon source resin, thereby improving the photocuring efficiency of the paste. In some embodiments of the present application, the carbon source resin is novolac epoxy acrylate, and the photoinitiator can catalyze the curing of the carbon source resin and the photocurable resin at the same time, so that the silicon carbide ceramic body can be cured and formed. In the embodiment of the present application, the photoinitiator includes diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,2-dimethoxy-2-phenylacetophenone, 2-iso One or more of propylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexyl phenyl ketone. In the embodiments of the present application, the photocurable resin includes one or more of trimethylolpropane triacrylic acid, 1,6-hexanediol diacrylate and polydihexaacrylate. The use of the above-mentioned photo-curable resin can ensure that the photo-cured ceramic body has high strength and hardness.

In the embodiment of the present application, the mass percentage content of the photocurable resin in the photocurable ceramic slurry is 10%-40%. The mass percentage content of the photocurable resin in the photocurable ceramic slurry may specifically be, but not limited to, 10%, 20%, 30% or 40%. Controlling the content of the photo-curable resin can ensure that the photo-cured ceramic body has high photo-curing precision. In the embodiment of the present application, the mass percentage content of the photoinitiator in the photocurable ceramic slurry is 0.1%-2%. In the embodiments of the present application, the mass ratio of the photocurable resin to the photoinitiator is 1:(0.01-0.05). The mass ratio of the photocurable resin to the photoinitiator may specifically be, but not limited to, 1:0.01, 1:0.02, 1:0.03, 1:0.04 or 1:0.05. Controlling the mass ratio of the photocurable resin to the photoinitiator can ensure that the ceramic slurry has a moderate photocuring rate, so that the final prepared silicon carbide ceramic has stable performance.

In this application, adding a dispersant can ensure that the SiC@SiO ₂ powder is uniformly dispersed in the photocurable ceramic slurry and improve the stability of the ceramic slurry. In the embodiments of the present application, the dispersant may be one or more of acrylate-based dispersants, polyurethane-based dispersants, and polyester-based dispersants. In some embodiments of the present application, the grade of the dispersant is KY100. In the embodiment of the present application, the mass percentage content of the dispersant in the photocurable ceramic slurry is 2%-6%. The mass percentage content of the dispersant in the photocurable ceramic slurry may be, but not limited to, 2%, 3%, 4%, 5% or 6%.

In the embodiment of the present application, the viscosity of the photocurable ceramic slurry is 1 Pa·s-5 Pa·s. The photocurable ceramic slurry of the present application has low viscosity and good fluidity, which is beneficial to the preparation of silicon carbide ceramics with high precision and complex structure.

The photocuring ceramic slurry provided by the application has high photocuring efficiency and good photocuring performance; and the photocuring ceramic slurry has uniform components and good stability; High, with good high temperature resistance and structural strength.

The present application also provides a method for preparing the above-mentioned photocurable ceramic slurry, which includes: after uniformly mixing SiC@SiO ₂ powder, photocurable resin, carbon source resin, photoinitiator and dispersant, the photocurable ceramic slurry is obtained. In some embodiments of the present application, the mixing process is as follows: the SiC@SiO ₂ powder, photocurable resin, carbon source resin, photoinitiator and dispersant are mechanically stirred, and then ball-milled in a planetary ball mill to obtain photocurable ceramic slurry . In some embodiments of the present application, the mechanical stirring time is 20-40 min, the rotation speed of the ball milling is 200 r/min-500 r/min, and the ball milling time is 2 h-24 h.

In the embodiment of the present application, the preparation method of SiC@SiO ₂ powder includes chemical vapor deposition method and high temperature oxidation method. In some embodiments of the present application, the SiC@SiO ₂ powder is prepared by a high-temperature oxidation method. Using the high-temperature oxidation method, a uniform and dense SiO ₂ layer can be formed on the surface of the SiC particles, which is beneficial for the SiO ₂ layer to completely coat the SiC particles. ; and the SiO ₂ layer can be closely combined with SiC, thereby ensuring that the silicon carbide ceramic has good structural stability. In addition, the high-temperature oxidation method has a low cost and is conducive to industrial production. In the embodiment of the present application, the principle of the high temperature oxidation method is: under the atmospheric environment and high temperature conditions, SiC can undergo a passive oxidation reaction with oxygen in the air, so as to generate a dense SiO layer _on the surface of SiC, that is, to obtain SiC @SiO ₂ powder.

In some embodiments of the present application, the preparation process of the photocurable ceramic slurry is as follows:

Step 100: heat the SiC powder at 800°C-1200°C for 1h-20h to obtain a crude SiC@SiO ₂ powder;

Step 200: post-processing the crude SiC@SiO ₂ powder to obtain SiC@SiO ₂ powder;

Step 300: After uniformly mixing the SiC@SiO ₂ powder, the photocurable resin, the carbon source resin, the photoinitiator and the dispersant, a photocurable ceramic slurry is obtained.

Please refer to FIG. 1 . FIG. 1 is a flow chart of a preparation process of a photocurable ceramic slurry according to an embodiment of the present application. Wherein, steps 100 and 200 are the preparation of SiC@SiO ₂ powder, and the SiC@SiO ₂ powder is prepared by a high temperature oxidation method. In the embodiment of the present application, the temperature of the high-temperature oxidation method is 800°C-1200°C, the heating rate of the high-temperature oxidation method is 1°C/min-5°C/min, and the reaction time of the high-temperature oxidation method is 1h-20h. Wherein, the temperature of the high-temperature oxidation method may specifically be, but not limited to, 800°C, 900°C, 1000°C, 1100°C or 1200°C. Controlling the temperature of the high-temperature oxidation method can effectively adjust the thickness of the _SiO2 shell layer in the SiC@ _SiO2 powder, thereby ensuring that the photocurable ceramic slurry has good photocuring properties.

In this application, the particle size of the crude SiC@SiO ₂ powder obtained by the high-temperature oxidation method is not uniform enough, and the crude SiC@SiO ₂ powder needs to be post-treated to obtain a photocurable ceramic slurry with good performance. In the embodiment of the present application, the post-processing of the crude SiC@SiO ₂ powder includes crushing and sieving. In the embodiments of the present application, the equipment used in the crushing process may be one or more of a mechanical impact pulverizer, an air jet pulverizer, a ball mill, a vibration mill, and a stirring mill. In some embodiments of the present application, the crushing method is wet ball milling.

In the embodiment of the present application, the material-to-ball ratio of the wet ball milling is 1:(2-4), and the ball milling time of the wet ball milling is 12h-48h. In some embodiments of the present application, the solvent of the wet ball milling is ethanol, and the volume ratio of ethanol to the crude SiC@SiO ₂ powder is 1:(1-19). When ethanol is used as the solvent, the ball milling time of the crude SiC@SiO ₂ powder can be well shortened and the ball milling efficiency can be improved. In some embodiments of the present application, a silane coupling agent is also added in the wet ball milling process, and the mass ratio of the crude SiC@SiO ₂ powder to the silane coupling agent is 1:(0.005-0.1). Adding silane coupling agent during ball milling can improve the dispersibility of SiC@SiO ₂ powder in photocurable ceramic slurry and reduce the viscosity of ceramic slurry, which is beneficial to improve the structural accuracy of SiC@SiO ₂ ceramic green body. In some embodiments of the present application, the brand of the silane coupling agent is KH570. In the embodiment of the present application, after the wet ball milling is completed, the mixture is filtered and dried to obtain SiC@SiO ₂ powder. In some embodiments of the present application, the mesh number used for sieving the SiC@SiO ₂ powder is 70 mesh to 100 mesh.

The preparation method of the photocurable ceramic slurry provided by the present application is easy to operate and suitable for industrial mass production; in the preparation process of the slurry, the high-temperature oxidation method can efficiently coat SiO ₂ on the surface of SiC, thereby effectively reducing the effect of SiC on ultraviolet light. Absorb and reduce the refractive index difference between SiC and photocurable resin; the content of SiO ₂ on the surface can be adjusted by setting the oxidation process parameters, and adding an appropriate content of carbon source resin according to the content of SiO ₂ can achieve Control of the composition of silicon carbide ceramics, thereby adjusting the properties of silicon carbide ceramics.

The present application also provides a method for preparing silicon carbide ceramics. Please refer to FIG. 2 , which is a flow chart of the preparation process of silicon carbide ceramics provided by an embodiment of the present application. The preparation method of silicon carbide ceramics comprises the following steps:

Step S1: photocuring the photocurable ceramic slurry to obtain a SiC@SiO ₂ ceramic body;

Step S2: the SiC@SiO ₂ ceramic body is heated by programmed temperature to obtain a SiC@SiO ₂ /C ceramic body;

Step S3: heat preservation of the SiC@SiO ₂ /C ceramic body at 1000° C.-1650° C. for 2h-8h to obtain silicon carbide ceramics.

In the embodiment of the present application, step S1 specifically includes: pouring the photocuring ceramic slurry into the material tank of the photocuring molding equipment, then importing the model data of the ceramic part to be prepared, setting processing parameters at the same time, and obtaining SiC@SiO after equipment processing ₂ ceramic body. In some embodiments of the present application, the model data of the ceramic part to be prepared is obtained by designing a three-dimensional model of the ceramic part by using three-dimensional modeling software and then performing data layering. In the embodiments of the present application, the photocuring molding equipment includes a stereolithography molding machine (Stereolithography, SLA) and a digital light processing molding machine (Digital Light Processing, DLP). In some embodiments of the present application, the photo-curing molding equipment is a stereo photo-curing molding machine, the laser power of the stereo photo-curing molding machine is 0.1w-3w, the scanning speed is 1000mm/s-4000mm/s, and the layer thickness in the processing parameters 10μm-150μm. In some embodiments of the application, the light curing molding device is a digital light processing molding machine, the laser power of the digital light processing molding machine is 7mw/cm2-100mw/cm2, the exposure time of the digital light processing molding machine is 1s-90s, and the digital light processing molding machine is 1s-90s. The layer thickness of the molding machine is 10μm-150μm.

In step S2, the carbon source resin and the photocurable resin can be thermally decomposed to form carbon through temperature programming to obtain a SiC@SiO ₂ /C ceramic green body. In the embodiment of the present application, the temperature conditions of the temperature program are as follows: the temperature is raised to 150°C-220°C at a heating rate not higher than 3°C/min, and the temperature is kept for 1-3 hours; the temperature is raised to a temperature not higher than 3°C/min 250°C-380°C, hold for 1-3h; raise the temperature to 700°C-900°C at a heating rate not higher than 3°C/min, hold for 1-3h. In some embodiments of the present application, the temperature conditions for the programmed temperature rise are: heating to 160°C at a heating rate of 1°C/min-3°C/min, and holding for 2 hours; heating to 1°C/min-3°C/min at a heating rate 300°C, hold for 2h; heat up to 800°C at a heating rate of 1°C/min-3°C/min, and hold for 2h. By controlling the temperature conditions of the thermal decomposition of the resin, the impact of the volume change caused by the change of the ceramic composition during the heating process of the ceramic body can be alleviated (the ceramic composition here includes not only the raw materials in the slurry, but also the resin and dispersion during the sintering process. The carbon, CO, C ₂ , CH 4 and H 2 O, etc. generated by the pyrolysis of the agent, thereby improving the structural strength of silicon carbide ceramics.

In the present application, step S3 is a carbothermic reduction reaction of SiO ₂ , and SiO ₂ on the surface of SiC can be eliminated through the carbothermic reduction reaction, thereby obtaining silicon carbide ceramics. In the embodiment of the present application, the temperature of the carbothermic reduction reaction is 1000°C-1700°C, and the holding time is 2-8h. In some embodiments of the present application, the temperature of the carbothermic reduction reaction is 1050° C.-1650° C., and the holding time is 3-6 h. The temperature of the carbothermic reduction reaction can be specifically, but not limited to, 1000°C, 1050°C, 1100°C, 1200°C, 1400°C, 1500°C or 1600°C. Controlling the temperature of the carbothermic reduction reaction can ensure that SiO ₂ and carbon can react effectively to form SiC, and reduce the occurrence of side reactions and avoid introducing other impurities.

In some embodiments of the present application, after the silicon carbide ceramic is obtained, the silicon carbide ceramic can also be densified by a silicon-carbon reaction. In the embodiment of the present application, the silicon-carbon reaction process includes: mixing silicon carbide ceramics and silicon particles in a vacuum sintering furnace, and keeping the temperature at 1500°C-1650°C for 10min-60min to obtain densified silicon carbide ceramics. The reaction temperature of the silicon-carbon reaction can be specifically, but not limited to, 1500°C, 1550°C, 1600°C or 1650°C. The reaction time of the silicon-carbon reaction may specifically be, but not limited to, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min. Under the above reaction conditions, the silicon particles can fully react with the carbon in the silicon carbide ceramic, thereby forming a densified silicon carbide ceramic. In the embodiment of the present application, the particle size of the silicon particles is 1 mm-5 mm.

The preparation method of silicon carbide ceramics provided by the present application is simple in operation, controllable in process, short in product preparation period and low in cost, and is suitable for industrial production.

The embodiments of the present application will be further described below in terms of a plurality of embodiments.

Example 1

A light-cured ceramic slurry and a preparation method thereof. The light-cured ceramic slurry is composed of raw materials with the mass ratio shown in Table 1.

Table 1 Example 1 Photocurable ceramic slurry raw material composition

Among them, the preparation process of SiC@SiO ₂ powder is as follows: SiC powder with a particle size of 10 μm is put into an atmospheric furnace for high-temperature oxidation. The oxidation temperature was 1200 °C, the oxidation time was 2 h, and the heating rate was 5 °C/min to obtain crude SiC@SiO ₂ powder; the crude SiC@SiO ₂ powder was subjected to wet ball milling, filtration drying and sieving to obtain SiC@SiO ₂ powder. The volume ratio of ethanol to crude SiC@SiO ₂ powder during wet ball milling was 4:1, and the addition amount of silane coupling agent KH570 was 3% of the mass of crude SiC@SiO ₂ powder.

The preparation method of the photocurable ceramic slurry is as follows:

Disperse the weighed SiC@ _SiO2 powder, 1,6-hexanediol diacrylate, novolac epoxy acrylate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and polyurethane After the agent was mechanically stirred for 30 minutes, it was poured into a ball-milling jar and ball-milled in a planetary ball mill with a ball-milling speed of 300r/min and a ball-milling time of 5h to obtain a light-cured ceramic slurry.

Example 2

A light-cured ceramic slurry and a preparation method thereof, the light-cured ceramic slurry is composed of raw materials with the mass ratio shown in Table 2.

Table 2 Example 2 Photocurable ceramic slurry raw material composition

Among them, the preparation process of SiC@SiO ₂ powder is as follows: SiC powder with a particle size of 5 μm is put into an atmospheric furnace for high-temperature oxidation. The oxidation temperature was 1100 °C, the oxidation time was 2 h, and the heating rate was 5 °C/min to obtain crude SiC@SiO ₂ powder; the crude SiC@SiO ₂ powder was subjected to wet ball milling, filtration drying and sieving to obtain SiC@SiO ₂ powder. The volume ratio of ethanol to crude SiC@SiO ₂ powder during wet ball milling was 4:1, and the addition amount of silane coupling agent KH570 was 3% of the mass of crude SiC@SiO ₂ powder.

The preparation method of the photocurable ceramic slurry is as follows:

Disperse the weighed SiC@ _SiO2 powder, 1,6-hexanediol diacrylate, novolac epoxy acrylate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and polyurethane After mechanical stirring for 30min, the agent was poured into a ball-milling jar and ball-milled in a planetary ball mill with a ball-milling speed of 400r/min and a ball-milling time of 3h to obtain a light-cured ceramic slurry.

Example 3

A light-cured ceramic slurry and a preparation method thereof, the light-cured ceramic slurry is composed of raw materials with the mass ratio shown in Table 3.

Table 3 Example 3 Photocurable ceramic slurry raw material composition

Among them, the SiC@SiO ₂ powder is composed of two kinds of particle grading, the particle size of the coarse particle powder is 5μm-30μm, the particle size of the fine particle powder is 0.1μm-5μm, and the volume ratio of the coarse particle powder to the fine particle powder is 1: 1.

The preparation method of the photocurable ceramic slurry is as follows:

The weighed SiC@SiO ₂ powder, trimethylolpropane triacrylic acid, 2130-type phenolic resin, 2,2-dimethoxy-2-phenylacetophenone and acrylate-type dispersant were mechanically stirred for 20 min. , poured into a ball-milling jar and ball-milled in a planetary ball mill with a ball-milling speed of 400r/min and a ball-milling time of 5h to obtain a light-cured ceramic slurry.

Example 4

A preparation method of silicon carbide ceramics, comprising the following steps:

1) Pour the photocurable ceramic slurry of Example 1 into the material tank of the digital light processing DLP molding equipment. The 3D model of the ceramic part was designed by 3D modeling software and imported into the photo-curing molding equipment. The ceramic photo-curing printing was carried out with a power density of 7.79mw/cm ² , an exposure time of 15s and a layer thickness of 50 μm to obtain a SiC@SiO ₂ ceramic body. ;

2) The SiC@SiO ₂ ceramic body was heated up by program, and the temperature program conditions were as follows: heating up to 200°C at a heating rate of 1°C/min, and holding for 2 h; heating up to 350°C at a heating rate of 1°C/min, holding the temperature 2h; heating up to 800°C at a heating rate of 1°C/min, holding for 2h to obtain a SiC@SiO ₂ /C ceramic body; continuing to heat up to generate a carbothermic reduction reaction, the heating process is: at a heating rate of 1°C/min from The temperature was raised from 800°C to 1500°C and kept for 2 hours to obtain silicon carbide ceramics.

Example 5

A preparation method of silicon carbide ceramics, comprising the following steps:

1) Pour the photocurable ceramic slurry of Example 2 into the material tank of the digital light processing DLP molding equipment. The 3D model of the ceramic part was designed by 3D modeling software and imported into the photo-curing molding equipment. The ceramic photo-curing printing was carried out with a power density of 7.79mw/cm ² , an exposure time of 15s and a layer thickness of 20 μm to obtain a SiC@SiO ₂ ceramic body. ;

2) The SiC@SiO ₂ ceramic body was heated up by program, and the temperature program conditions were as follows: heating up to 200°C at a heating rate of 1°C/min, and holding for 2 h; heating up to 350°C at a heating rate of 1°C/min, holding the temperature 2h; heating up to 800°C at a heating rate of 1°C/min, holding for 2h to obtain a SiC@SiO ₂ /C ceramic body; continuing to heat up to generate a carbothermic reduction reaction, the heating process is: at a heating rate of 1°C/min from The temperature was raised from 800°C to 1650°C and kept for 2 hours to obtain silicon carbide ceramics.

Example 6

A preparation method of silicon carbide ceramics, comprising the following steps:

1) Pour the photocurable ceramic slurry of Example 3 into the material tank of the digital light processing DLP molding equipment. The 3D model of the ceramic part was designed by 3D modeling software and imported into the photo-curing molding equipment, and the ceramic photo-curing printing was carried out with a power density of 7.79mw/cm ² , an exposure time of 15s and a layer thickness of 20 μm to obtain a SiC@SiO ₂ ceramic body ;

2) The SiC@SiO ₂ ceramic body was heated up by program, and the temperature program conditions were as follows: heating up to 200°C at a heating rate of 1°C/min, and holding for 2 h; heating up to 350°C at a heating rate of 1°C/min, holding the temperature 2h; heating up to 800°C at a heating rate of 1°C/min, holding for 2h to obtain a SiC@SiO ₂ /C ceramic body; continuing to heat up to generate a carbothermic reduction reaction, the heating process is: at a heating rate of 1°C/min from The temperature was raised from 800°C to 1650°C and kept for 2 hours to obtain silicon carbide ceramics.

3) Mixing silicon carbide ceramics with silicon particles with a particle size of 5 mm, placing them in a vacuum sintering furnace, and keeping the temperature at 1600° C. for 30 minutes to obtain densified silicon carbide ceramics.

Example 7

A preparation method of silicon carbide ceramics, comprising the following steps:

1) Pour the photocurable ceramic slurry of Example 3 into the trough of the stereo photocuring molding machine. The 3D model of the ceramic part was designed by 3D modeling software and imported into the photo-curing molding equipment, and the ceramic photo-curing printing was carried out with a laser power of 2.5w, a scanning speed of 3000mm/s and a layer thickness of 20μm to obtain a SiC@SiO ₂ ceramic body;

2) The SiC@SiO ₂ ceramic body was heated up by program, and the temperature program conditions were as follows: heating up to 200°C at a heating rate of 1°C/min, and holding for 2 h; heating up to 350°C at a heating rate of 1°C/min, holding the temperature 2h; heating up to 800°C at a heating rate of 1°C/min, holding for 2h to obtain a SiC@SiO ₂ /C ceramic body; continuing to heat up to generate a carbothermic reduction reaction, the heating process is: at a heating rate of 1°C/min from The temperature was raised from 800°C to 1500°C and kept for 2 hours to obtain silicon carbide ceramics.

3) Mixing silicon carbide ceramics with silicon particles with a particle size of 1 mm and placing them in a vacuum sintering furnace, and keeping the temperature at 1600° C. for 30 minutes to obtain densified silicon carbide ceramics.

To highlight the beneficial effects of the present application, the following comparative examples are set.

Comparative Example 1

A light-cured ceramic slurry and a preparation method thereof. The light-cured ceramic slurry is composed of raw materials with the mass ratio shown in Table 4.

Table 4 Comparative Example 1 Composition of raw materials of photocurable ceramic slurry

The preparation method of the photocurable ceramic slurry is as follows:

The weighed SiC powder, 1,6-hexanediol diacrylate, novolac epoxy acrylate, diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide and polyurethane-based dispersant were mechanically treated. After stirring for 30 min, pour it into a ball mill jar and perform ball milling in a planetary ball mill with a ball milling speed of 300 r/min and a ball milling time of 5 h to obtain a light-cured ceramic slurry.

Effect Example

In order to verify the performance of the photocured ceramic slurry and photocured ceramic prepared by the present application, the present application also provides effect examples.

1) Scanning electron microscope was used to characterize the morphology of the SiC@SiO ₂ powder prepared in Example 1 and Example 2, please refer to Figure 3 and Figure 4, Figure 3 is the SiC@SiO ₂ powder prepared in Example 1 of the application Figure 4 is the scanning electron microscope image of the SiC@SiO ₂ powder prepared in Example 2 of the application. It can be seen from Figure 3 that the particle size of the SiC@SiO ₂ powder in Example 1 is 1 μm-20 μm. It can be seen from Figure 4 that the particle size of the SiC@SiO ₂ powder in Example 2 is 1 μm-40 μm.

2) The photocuring efficiency test was carried out on the photocurable ceramic pastes of Examples 1-2 and Comparative Example 1, please refer to FIG. 5 and FIG. 6 , and FIG. 5 is the photocuring ceramics of Examples 1-2 and Comparative Example 1 of the application. A comparison diagram of the photocuring efficiency test of the paste. Figure 6 is a comparison diagram of the curing thickness of the photocurable ceramic paste in Example 1 and Comparative Example 1 of the application under the exposure time of 90s. Among them, (a) in Figure 6 is Comparative Example 1 The thickness diagram of the photocured ceramic paste cured under the exposure time of 90s, Figure 6(b) is the cured thickness diagram of the photocured ceramic paste of Example 1 under the exposure time of 90s. It can be seen from FIG. 5 that, under the same exposure time, the cured thickness of the photocurable ceramic pastes of Examples 1 and 2 are both greater than the cured thickness of the photocured ceramic paste of Comparative Example 1. It can be seen from (a) in Figure 6 that the cured thickness of the ceramic slurry in Comparative Example 1 is 44.7 μm under the exposure time of 90s. It can be seen from (b) in Figure 6 that under the exposure time of 90s, Example 1 The solidified thickness of the ceramic slurry was 89.9 μm, that is, the solidified thickness of the ceramic slurry of Example 1 was twice that of the ceramic slurry of Comparative Example 1. It can be seen that the photocuring paste obtained by coating SiC with SiO ₂ has high photocuring efficiency, which can effectively shorten the production cycle of silicon carbide ceramics.

3) The photocurable printing performance of the photocurable ceramic paste of Example 1 was tested, and the specific printing conditions were shown in Example 4. Please refer to FIG. 7 . FIG. 7 is a photo-cured printing effect diagram of the photo-cured ceramic paste of Example 1 of the application, wherein (a) in FIG. 7 is a three-dimensional model diagram of the ceramic part in Example 4, and (b) in FIG. 7 A photograph of the SiC@SiO ₂ ceramic body of Example 4. It can be seen from the comparison diagrams of (a) in FIG. 7 and (b) in FIG. 7 that the ceramic green body prepared by using the photocured ceramic slurry of Example 1 has a complete structure and high structural precision.

The above-mentioned embodiments only represent several embodiments of the present invention, and the descriptions thereof are specific and detailed, but should not be construed as a limitation on the scope of the patent of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims (9)

1. a photocurable ceramic slurry, is characterized in that, comprises each raw material of following mass percentage composition: SiC@SiO ₂ powder: 25%-60%; Light curing resin: 10%-40%; Carbon source resin: 10%-40%; Photoinitiator: 0.1%-2%; Dispersant: 2%-6%; The SiC@SiO ₂ powder includes a SiC core body and a SiO ₂ shell layer coated on the surface of the SiC core body; the ratio of the particle size of the SiC core body to the thickness of the SiO ₂ shell layer is 1:( 0.15-0.5); the SiC@SiO ₂ powder is prepared by a high-temperature oxidation method, and the high-temperature oxidation method includes: keeping the SiC powder at 800 ℃～1200 ℃ for 1h-20h to obtain a crude SiC@SiO ₂ powder, Crushing and sieving the crude SiC@SiO ₂ powder to obtain SiC@SiO ₂ powder; the SiC@SiO ₂ powder includes a first SiC@SiO ₂ powder and a second SiC@SiO ₂ powder; the first SiC@SiO 2 powder The particle size of the @SiO ₂ powder is greater than 0.1 μm and less than or equal to 5 μm; the particle size of the second SiC@SiO ₂ powder is greater than 5 μm and less than or equal to 32 μm; the second SiC@SiO ₂ powder and the first The volume ratio of the SiC@SiO ₂ powder is greater than 0 and less than or equal to 1; the residual carbon rate of the carbon source resin at 800°C is greater than or equal to 40%; the mass of the SiC@SiO ₂ powder and the carbon source resin The ratio is 1:(0.4-1). 2 . The photocurable ceramic slurry according to claim 1 , wherein the particle size of the SiC core is 0.1 μm-30 μm; the thickness of the SiO ₂ shell layer is 20 nm-2000 nm. 3 . 3. The photocurable ceramic paste of claim 1, wherein the carbon source resin comprises a phenolic resin. 4 . The photocurable ceramic slurry according to claim 1 , wherein the photocurable resin comprises trimethylolpropane triacrylic acid, 1,6-hexanediol diacrylate and polydihexaacrylate. 5 . one or more of. 5. The photocurable ceramic slurry of claim 1, wherein the photoinitiator comprises diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, 2,2-diphenyl In methoxy-2-phenylacetophenone, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxycyclohexylphenyl ketone one or more of. 6 . The photocurable ceramic slurry according to claim 1 , wherein the viscosity of the photocured ceramic slurry is 1 Pa·s-5 Pa·s. 7 . 7. a preparation method of silicon carbide ceramics, is characterized in that, comprises the following steps: The photo-cured ceramic slurry is photo-cured to obtain a SiC@SiO ₂ ceramic body; the photo-cured ceramic slurry includes the following raw materials by mass percentage: SiC@SiO ₂ powder: 25%-60%; Light curing resin: 10%-40%; Carbon source resin: 10%-40%; Photoinitiator: 0.1%-2%; Dispersant: 2%-6%; The SiC@SiO ₂ powder includes a SiC core body and a SiO ₂ shell layer coated on the surface of the SiC core body; the ratio of the particle size of the SiC core body to the thickness of the SiO ₂ shell layer is 1:( 0.15-0.5); the SiC@SiO ₂ powder is prepared by a high-temperature oxidation method, and the high-temperature oxidation method includes: keeping the SiC powder at 800 ℃～1200 ℃ for 1h-20h to obtain a crude SiC@SiO ₂ powder, Crushing and sieving the crude SiC@SiO ₂ powder to obtain SiC@SiO ₂ powder; the SiC@SiO ₂ powder includes a first SiC@SiO ₂ powder and a second SiC@SiO ₂ powder; the first SiC@SiO 2 powder The particle size of the @SiO ₂ powder is greater than 0.1 μm and less than or equal to 5 μm; the particle size of the second SiC@SiO ₂ powder is greater than 5 μm and less than or equal to 32 μm; the second SiC@SiO ₂ powder and the first The volume ratio of the SiC@SiO ₂ powder is greater than 0 and less than or equal to 1; the residual carbon rate of the carbon source resin at 800°C is greater than or equal to 40%; the mass of the SiC@SiO ₂ powder and the carbon source resin The ratio is 1:(0.4-1); The SiC@SiO ₂ ceramic body is heated by programmed temperature to carbonize the carbon source resin, and then kept at 1000° C.-1700° C. for 2h-8h to carbonize SiO ₂ to form SiC to obtain silicon carbide ceramics. 8. The preparation method according to claim 7, characterized in that, the conditions of the temperature-programmed temperature are as follows: the temperature is raised to 150-220°C at a heating rate not higher than 3°C/min, and the temperature is kept for 1-3h; The heating rate is higher than 3°C/min to 250°C-380°C, and the temperature is kept for 1-3h; 9 . The preparation method according to claim 7 , wherein the preparation method further comprises: mixing the silicon carbide ceramics with silicon particles, and keeping the temperature at 1500° C.-1650° C. for 10min-60min to obtain a densified ceramic. 10 . Silicon carbide ceramics.

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