CN108892515A - A kind of photocuring silicon nitride ceramics slurry, silicon nitride ceramics and preparation method thereof - Google Patents

Abstract

The application belongs to the technical field of ceramic materials, and in particular relates to a light-cured silicon nitride ceramic slurry, silicon nitride ceramics and a preparation method thereof. This application provides a light-cured silicon nitride ceramic slurry, silicon nitride ceramics and a preparation method thereof, which can effectively solve the problem of low solid phase content of traditional silicon nitride ceramic slurry and single-layer curing of its light-cured molding. Technical defect of low thickness. The present application discloses a method for preparing a light-cured silicon nitride ceramic slurry, comprising the following steps: step 1, mixing a silicon nitride powder solution, a sintering aid solution, a dispersant and a precipitant to obtain a precipitation solution, and The precipitation solution is filtered to obtain a mixed solid; step 2, the mixed solid is cleaned, calcined and ball milled to obtain a coated powder; step 3, the coated powder, photocurable resin, photoinitiator and dispersed Agents were mixed to obtain photocurable silicon nitride ceramic slurry.

Description

A kind of light-cured silicon nitride ceramic slurry, silicon nitride ceramics and preparation method thereof

technical field

The application belongs to the technical field of ceramic materials, and in particular relates to a light-cured silicon nitride ceramic slurry, silicon nitride ceramics and a preparation method thereof.

Background technique

Silicon nitride ceramics are currently one of the most promising structural ceramics. Its excellent high-temperature performance and chemical stability make it play an important role in the high-temperature field. With the development of science and technology, the application fields and usage requirements of silicon nitride ceramics are becoming more and more stringent. At present, the traditional manufacturing method is to form silicon nitride powder or slurry through a mold, and then undergo post-processing such as sintering and machining to obtain the required ceramic components. This mold forming process makes the component processing cost high and difficult. The preparation of parts with complex structures such as radians and hollows severely limits the application and development of silicon nitride ceramics.

In response to this problem, many scholars have proposed a net-size forming method to directly form components of the required shape through the additive manufacturing method (solid mold-free forming technology). This technology can prepare silicon nitride ceramics with complex structures, which makes the preparation The cost is reduced, and the application field of silicon nitride ceramics is broadened. The current rapid prototyping methods for ceramics include: three-dimensional printing (3DP), selective laser melting (SLM) and photolithography (SLA/DLP). The photo-curing molding method is easier to prepare dense ceramic parts than the other two mainstream methods. But the light-curing molding method requires a suitable silicon nitride ceramic slurry. Scholars have studied the silicon nitride ceramic slurry used for photocuring molding, and there are the following problems: (1) the solid phase content of the traditional silicon nitride ceramic slurry is low; (2) the single Layer cured thickness is low. These two main problems limit the molding of silicon nitride ceramics by light-curing molding technology.

application content

In view of this, the application provides a light-cured silicon nitride ceramic slurry, silicon nitride ceramics and a preparation method thereof, which can effectively solve the problem of low solid phase content of traditional silicon nitride ceramic slurry and its light-cured molding The single-layer cured thickness is low technical defect.

The preparation method of a light-cured silicon nitride ceramic slurry of the present application comprises the following steps:

Step 1, mixing the silicon nitride powder solution, the sintering aid solution, the first dispersant and the precipitating agent to obtain a precipitating solution, and filtering the precipitating solution to obtain a mixed solid;

Step 2. After cleaning the mixed solid, calcining and ball milling, the coated powder is obtained;

Step 3, mixing the coating powder, photocurable resin, photoinitiator and second dispersant to obtain photocurable silicon nitride ceramic slurry.

Preferably, the silicon nitride powder in the silicon nitride powder solution has a particle size of 0.2-1 μm.

Preferably, the concentration of the silicon nitride powder solution is 0.1-1 mol/L.

Preferably, the sintering aid solution includes one or more of aluminum chloride hexahydrate solution, aluminum nitrate nonahydrate solution, yttrium nitrate hexahydrate solution, magnesium chloride hexahydrate solution and magnesium nitrate hexahydrate solution.

Preferably, the concentration of the sintering aid solution is 0.01-0.5 mol/L.

More preferably, the concentration of the sintering aid solution is 0.01-0.04 mol/L.

Preferably, the precipitant includes one or more of NaOH, KOH, NH ₃ ·H ₂ O and CO(NH ₂ ) ₂ .

Preferably, the pH value of the precipitation solution is 8-12.

More preferably, the pH value of the precipitation solution is 9-11.

The present application also discloses a silicon nitride ceramic slurry, which is prepared by the preparation method of the light-cured silicon nitride ceramic slurry.

The application also discloses a method for preparing silicon nitride ceramics, comprising the following steps:

Step 1. Using the light-cured silicon nitride ceramic slurry prepared by the method for preparing the light-curable silicon nitride ceramic slurry or the light-curable silicon nitride ceramic slurry as a raw material, according to the section outline of the part drawing Carry out layer-by-layer solidification and superposition processing to obtain a molded green body;

Step 2, debinding and sintering the molded green body to obtain silicon nitride ceramics.

The application also discloses a silicon nitride ceramic, including the preparation method of the silicon nitride ceramic.

In this application, the surface coating of silicon nitride powder is realized through the chemical precipitation method of mixing silicon nitride powder solution, sintering aid solution, dispersant and precipitant, and the surface characteristics of silicon nitride powder are changed. The application has the following advantages: (1) Change the surface characteristics of silicon nitride powder, reduce the refractive index difference between powder and resin, improve the solid content of photocurable silicon nitride ceramic slurry and the photocurable silicon nitride ceramic slurry The solidification depth of the slurry; (2) The uniform dispersion of the sintering aid is realized. It can be seen from the experimental data that the solidification depth of the silicon nitride ceramics prepared from the photocured silicon nitride ceramic slurry obtained by coating the surface of the silicon nitride powder by chemical precipitation is significantly improved, and its density is also within the acceptable range . This application provides a silicon nitride ceramic slurry suitable for light-curing molding and a method for preparing silicon nitride ceramics by using it, which further improves the feasibility of printing silicon nitride ceramics through 3D, and will broaden the scope of silicon nitride ceramics. application field.

Detailed ways

This application provides a silicon nitride ceramic slurry and silicon nitride ceramics and their preparation method and application, which are used to solve the problem of the low solid phase content of traditional silicon nitride ceramic slurry and the long exposure time of its photocuring molding And technical defects that are prone to scattering phenomena.

The following will clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

The application provides a specific embodiment of a method for preparing a light-cured silicon nitride ceramic slurry, the preparation steps of which are as follows:

(a) Prepare 0.1-1mol/L silicon nitride powder aqueous solution, 0.01-0.5mol/L sintering aid solution, mix silicon nitride powder solution, sintering aid solution, first dispersant and precipitant , chemically precipitating and coating the silicon nitride powder to obtain a precipitation solution, and performing solid-liquid filtration on the precipitation solution to obtain a mixed solid, wherein the pH of the precipitation solution is 8-12;

(b) Wash the mixed solid with deionized water and alcohol for several times to remove the powder obtained after the separation of residual ions. After the powder is dried, it is calcined and ball milled. Raise the temperature at a rate of 1-3°C/min to 500-800°C and keep it warm for 1-3 hours. The ball milling method is to pass through a 100-mesh sieve after ball milling for 6 hours to obtain a coated powder;

(c) Mixing the coating powder, the photocurable resin, the photoinitiator and the second dispersant to obtain a photocurable silicon nitride ceramic slurry.

Wherein, the particle size of the silicon nitride powder in the silicon nitride powder solution is 0.2-1 μm.

Wherein, the concentration of the silicon nitride powder solution is 0.1-1mol/L.

Wherein, the silicon nitride powder solution is an aqueous solution of silicon nitride powder.

Among them, the sintering aid solution includes aluminum chloride hexahydrate solution (AlCl ₃ ·H ₂ O), aluminum nitrate nonahydrate solution (Al(NO ₃ ) ₃ ·9H ₂ O), yttrium nitrate hexahydrate solution (Y(NO ₃ ) ₃ ·6H ₂ O), magnesium chloride hexahydrate solution (MgCl ₂ ·6H ₂ O) and magnesium nitrate hexahydrate solution (Mg(NO ₃ ) ₂ ·6H ₂ O).

Wherein, the concentration of each sintering aid solution is 0.01-0.5 mol/L.

More preferably, the concentration of each sintering aid solution is 0.01-0.04 mol/L.

Wherein, the first dispersant includes one or more of sodium polyacrylate, ammonium polyacrylate or methyl cellulose.

Wherein, the addition amount of the first dispersant is 0.5-1.5wt% of the silicon nitride powder, the silicon nitride powder is the silicon nitride powder in the silicon nitride powder solution, and the first dispersant is the silicon nitride powder The silicon powder is dispersed in water, which is beneficial to coating, and has a different effect from the second dispersant.

Wherein, the mixing condition in step (a) is one or more of magnetic stirring, mechanical stirring or heating.

Wherein, the rotating speed of magnetic stirring is 0-1250 rpm, the rotating speed of mechanical stirring is 0-2000 rpm, and the heating temperature is 50-80°C.

Wherein, the precipitating agent is one of NaOH, KOH, NH ₃ ·H ₂ O or CO(NH ₂ ) ₂ .

More preferably, the pH value of the precipitation solution is 9-11.

Wherein, the filtration method in step (a) is vacuum suction filtration or rotary centrifugation, the vacuum degree is 0.09MPa, and the rotation speed is 8000-12000rpm.

Wherein, the method of calcining in step (b) is as follows: the temperature of the powder is raised to 500-800° C. for 1-3 hours under air at a rate of 1-3° C./min.

Wherein, the photocurable resin includes one or more of 1,6-hexanediol diacrylate (HDDA), pentaerythritol tetraacrylate (PETTA) and trimethylolpropane triacrylate (TMPTA).

Wherein, the mass percentage of the added photocurable resin is 40-60% of the photocurable silicon nitride ceramic slurry.

Among them, the photoinitiator is selected from the group consisting of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819 ), (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) and 2-isopropylthioxanthone (ITX).

Wherein, the added mass of the photoinitiator is 1-2wt% of the photocurable resin.

Specifically, the second dispersant includes one or more of BYK-9076, BYK-163 and BYK-9077.

Specifically, the added amount of the second dispersant is 1-2 wt% of the coating powder, and the function of the second dispersant is to fully disperse the coating powder in the slurry preparation, which is beneficial to reduce the viscosity of the product.

A method for forming silicon nitride ceramics provided by the application, the preparation steps are as follows:

Step 1. Using the above-mentioned light-cured silicon nitride ceramic slurry as a raw material, perform layer-by-layer solidification and superposition processing according to the slice outline of the part drawing to obtain a molded body;

Step 2, debinding and sintering the molded green body to obtain silicon nitride ceramics.

Specifically, the step of forming in step 1 is as follows: import the three-dimensional part drawing of the model into the light-curing molding machine by using software slices, and then add the prepared light-curing silicon nitride ceramic slurry into the light-curing molding machine. According to the program setting, The ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally a molded body is obtained.

Specifically, the method of debinding is: heating the molded body to 300°C at a rate of 0.5-2°C/min in vacuum or in the air and keeping it for 1-3 hours, and then raising the temperature to 600°C at a rate of 0.5-2°C/min Keep warm for 1-3 hours.

Specifically, the sintering method is as follows: the green body after debinding is heated to 1700-1850° C. for 1-3 hours at a rate of 0.5-3° C./min under nitrogen or vacuum atmosphere, and the pressure is 0.1-10 MPa.

Wherein, the raw materials used in the following examples are all commercially available or self-made.

Example 1

The embodiment of the present application provides the first preparation method of photocured silicon nitride ceramic slurry, the steps are as follows:

(a) Using a magnetic stirrer (rotating speed is 1250rpm), add 0.8wt% sodium polyacrylate (sodium polyacrylate is 0.8wt% of silicon nitride powder) in 0.1mol/L silicon nitride deionized aqueous solution, Add 0.03mol/L aqueous solution of aluminum nitrate nonahydrate Al(NO ₃ ) ₃ ·9H ₂ O, NH ₃ ·H ₂ O and 0.01mol/L aqueous solution of yttrium nitrate hexahydrate Y(NO ₃ ) ₃ ·6H ₂ O to nitrogen In silicon dioxide deionized aqueous solution, stir and mix to obtain a precipitation solution; adjust the pH of the precipitation solution to 10.5, and let it stand;

(b) Use a centrifuge to separate the powder from the precipitation solution, wash the separated powder three times with deionized water and once with alcohol, dry the powder for 24 hours, then calcinate the powder in air, The condition is to raise the temperature at a rate of 1°C/min to 500°C for 3 hours, ball mill for 6 hours after calcination, and pass through a 100-mesh sieve to obtain a coated powder;

(c) Mix 50g of coated powder after sieving with 23g of 1,6-hexanediol diacrylate (HDDA), 0.4g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819) mixed with 0.5g BYK-9076 to obtain photocurable silicon nitride ceramic slurry.

The embodiment of the present application provides the first forming method of silicon nitride ceramics, the steps are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally the molded body is obtained;

The second step: post-processing: deglue the molded body in the first step in the air, raise the temperature to 300°C at a rate of 0.5°C/min and keep it for 1h, then raise the temperature to 600°C at a rate of 1°C/min and keep it for 3h ; After debinding, the green body is sintered under nitrogen at a rate of 3°C/min to 1820°C for 2h, and the air pressure is 0.1MPa to obtain silicon nitride ceramics with complex shapes.

Example 2

The embodiment of the present application provides the second preparation method of silicon nitride ceramic slurry, the steps are as follows:

(a) Add 0.1mol/L silicon nitride deionized aqueous solution, 0.8wt% sodium polyacrylate, 0.03mol/L aluminum nitrate nonahydrate Al(NO ₃ ) ₃ 9H ₂ O, NaOH and 0.01mol/L six The aqueous solution of yttrium nitrate hydrate (Y(NO ₃ ) ₃ 6H ₂ O) was mixed with a mechanical stirrer (1500 rpm) to obtain a precipitation solution; the pH of the precipitation solution was adjusted to 11.5, heated to 60°C, and allowed to stand;

(b) Use vacuum filtration (vacuum degree of 0.09MPa) to separate the powder from the precipitation solution. The separated powder is washed 4 times with deionized water and 1 time with alcohol, and the powder is dried for 24 hours. Calcination under vacuum at a rate of 2°C/min to 500°C for 2 hours, ball milling for 6 hours after calcination, and passing through a 100-mesh sieve to obtain a coated powder;

(c) Mix 50g of coated powder after sieving with 23g of pentaerythritol tetraacrylate (PETTA), 0.4g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) and 0.5g of BYK- 9077 mixed to obtain light-cured silicon nitride ceramic slurry.

The embodiment of the present application provides a second method for forming silicon nitride ceramics, the steps of which are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally the molded body is obtained;

The second step: post-processing: deglue the formed body in the first step in vacuum, heat up to 300°C at a rate of 1°C/min and keep it for 1.5h, and then heat it up to 600°C at a rate of 1°C/min 2h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1820°C at a rate of 2°C/min for 2h, and the air pressure is 8MPa to obtain silicon nitride ceramics with complex shapes.

Example 3

The embodiment of the present application provides the preparation method of the 3rd kind of silicon nitride ceramic slurry, and its steps are as follows:

(a) Add 0.2mol/L silicon nitride deionized aqueous solution, 0.8wt% sodium polyacrylate, 0.05mol/L aluminum nitrate nonahydrate Al(NO ₃ ) ₃ 9H ₂ O, KOH and 0.03mol/L six The magnesium chloride hydrate MgCl ₂ ·6H ₂ O aqueous solution was stirred and mixed with a mechanical stirrer (rotating at 1800 rpm) to obtain a precipitation solution; the pH of the precipitation solution was adjusted to 10.5, heated to 60°C, and allowed to stand;

(b) Use vacuum filtration (vacuum degree of 0.09MPa) to separate the powder from the precipitation solution. The separated powder is washed with deionized water for 3 times and alcohol for 1 time. The powder is dried for 24 hours. The calcination under the air is heated up to 500°C at a rate of 2°C/min and kept for 2h, ball milled for 6h after calcination, and coated powder is obtained by passing through a 100-mesh sieve;

(c) Mix 50g of coated powder after sieving with 35g of trimethylolpropane triacrylate (TMPTA), 0.35g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) and Mix 1g of BYK-9075 to obtain photocurable silicon nitride ceramic slurry.

The embodiment of the present application provides a third method for forming silicon nitride ceramics, the steps of which are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally the molded body is obtained;

The second step: post-processing: deglue the molded body in the first step in vacuum, raise the temperature to 300°C at a rate of 0.5°C/min and keep it for 0.5h, and then raise the temperature to 600°C at a rate of 0.5°C/min and keep it warm 3h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1820°C at a rate of 2°C/min for 2h, and the air pressure is 0.1MPa to obtain silicon nitride ceramics with complex shapes.

Example 4

The embodiment of the present application provides the fourth preparation method of photocured silicon nitride ceramic slurry, the steps are as follows:

(a) Add 0.1mol/L silicon nitride deionized aqueous solution, 1.2wt% sodium polyacrylate, 0.5mol/L aluminum nitrate nonahydrate Al(NO ₃ ) ₃ 9H ₂ O, KOH and 0.03mol/L six Aqueous magnesium nitrate Mg(NO ₃ ) ₂ ·6H ₂ O aqueous solution was stirred and mixed with a mechanical stirrer (1000 rpm) to obtain a precipitation solution; the pH of the precipitation solution was adjusted to 9.5, heated to 50°C, and allowed to stand;

(b) Use a centrifuge (8000 rpm) to separate the powder from the precipitation solution. The separated powder is washed 3 times with deionized water and 1 time with alcohol. Dry the powder for 24 hours, and then dry the powder in the air The calcination was heated up to 500°C at a rate of 2°C/min and kept for 2 hours. After calcination, it was ball milled for 6 hours and passed through a 100-mesh sieve to obtain a coated powder;

(c) Mix 50g of coated powder after sieving with 35g of trimethylolpropane triacrylate (TMPTA), 0.35g of 2-hydroxy-2-methyl-1-phenyl-1-propanone (1173) and 1.5g BYK-9077 was mixed to obtain photocurable silicon nitride ceramic slurry.

The embodiment of the present application provides a fourth method for forming silicon nitride ceramics, the steps of which are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally a molded body is obtained;

The second step: post-processing: deglue the molded body in the first step in vacuum, raise the temperature to 300°C at a rate of 0.5°C/min and keep it for 0.5h, and then raise the temperature to 600°C at a rate of 0.5°C/min and keep it warm 3h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1850°C at a rate of 1°C/min for 2h, and the air pressure is 0.1MPa to obtain silicon nitride ceramics with complex shapes.

Example 5

The embodiment of the present application provides the preparation method of the fifth light-cured silicon nitride ceramic slurry, the steps are as follows:

(a) Add 1.2 wt% sodium polyacrylate, 0.5 mol/L aluminum nitrate nonahydrate Al(NO ₃ ) ₃ ·9H ₂ O, CO(NH ₂ ) ₂ and 0.2 Stir and mix the mol/L magnesium nitrate hexahydrate Mg(NO ₃ ) ₂ ·6H ₂ O aqueous solution to obtain a precipitation solution; adjust the pH of the precipitation solution to 9.5, heat to 60°C, and let stand;

(b) Use a centrifuge (10000rpm) to separate the powder from the precipitation solution. The separated powder is washed 3 times with deionized water and 1 time with alcohol. Dry the powder for 24 hours, and then dry the powder under air. The calcination was heated up to 500°C at a rate of 2°C/min and kept for 2 hours. After calcination, it was ball milled for 6 hours and passed through a 100-mesh sieve to obtain a coated powder;

(c) Mix 50g of coated powder after sieving with 40g of pentaerythritol tetraacrylate (PETTA), 0.4g of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO) and 1.5g of Mix BYK-9077 to obtain photocurable silicon nitride ceramic paste.

The embodiment of the present application provides a fifth method for forming silicon nitride ceramics, the steps of which are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally the molded body is obtained;

The second step: post-processing: deglue the molded body in the first step in vacuum, raise the temperature to 300°C at a rate of 0.5°C/min and keep it for 0.5h, and then raise the temperature to 600°C at a rate of 0.5°C/min and keep it warm 3h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1820°C at a rate of 2°C/min for 2h, and the air pressure is 0.1MPa to obtain silicon nitride ceramics with complex shapes.

Example 6

The embodiment of the present application provides the preparation method of the 6th light-cured silicon nitride ceramic slurry, and its steps are as follows:

(a) Using a magnetic stirrer (rotating at 1500rpm), add 1.2wt% sodium polyacrylate and 0.1mol/L aluminum nitrate nonahydrate Al(NO ₃ ) ₃ 9H to 0.2 mol/L silicon nitride deionized aqueous solution Stir and mix ₂ O, CO(NH ₂ ) ₂ and 0.08mol/L magnesium nitrate hexahydrate Mg(NO ₃ ) ₂ 6H ₂ O aqueous solution to obtain a precipitation solution; adjust the pH of the precipitation solution to 9, and let stand;

(b) Use a centrifuge (12000rpm) to separate the powder from the precipitation solution, wash the separated powder twice with deionized water and twice with alcohol, dry the powder for 24 hours, and then dry the powder under air The calcination was heated up to 500°C for 2 hours at a rate of 1°C/min, ball milled for 6 hours after calcination, and coated powder was obtained by passing through a 100-mesh sieve;

(c) Mix 50g of coated powder after sieving with 40g of pentaerythritol tetraacrylate (PETTA), 0.4g of (2,4,6-trimethylbenzoyl) diphenylphosphine oxide (TPO) and 1g of BYK -9076 mixed to obtain photocurable silicon nitride ceramic slurry.

The embodiment of the present application provides a sixth method for forming silicon nitride ceramics, the steps of which are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally a molded body is obtained;

The second step: post-processing: deglue the molded body in the first step, heat it up to 300°C at a rate of 0.5°C/min and keep it for 0.5h, and then heat it up to 600°C at a rate of 1°C/min 2h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1850°C at a rate of 2°C/min for 3h, and the air pressure is 10MPa to obtain silicon nitride ceramics with complex shapes.

comparative example

The application also provides a comparative example, which is a silicon nitride ceramic slurry prepared from uncoated silicon nitride powder, and the specific preparation method of the silicon nitride ceramic prepared from the silicon nitride ceramic slurry is as follows :

(1) Aluminum oxide, yttrium oxide and silicon nitride powders are ball milled and mixed according to the ratio of 4:6:90 to obtain mixed powders;

(2) Mix 50g of mixed powder with 40g of pentaerythritol tetraacrylate (PETTA), 0.4g of (2,4,6-trimethylbenzoyl)diphenylphosphine oxide (TPO) and 1g of BYK-9076 to obtain light Curing of silicon nitride ceramic slurries.

The forming method of the silicon nitride ceramics of comparative example is provided below, and its steps are as follows:

The first step, molding: import the three-dimensional part drawing of the model into the light-curing molding machine using software slices, and then add the prepared photo-curing silicon nitride ceramic slurry into the photo-curing molding machine. According to the program setting, the photo-curing nitride The silicon ceramic slurry is solidified layer by layer, accumulated layer by layer, and finally a molded body is obtained;

The second step: post-processing: deglue the molded body in the first step, heat it up to 300°C at a rate of 0.5°C/min and keep it for 0.5h, and then heat it up to 600°C at a rate of 1°C/min 2h; the green body after debinding is sintered under nitrogen, and the temperature is raised to 1820°C at a rate of 2°C/min for 2h, and the air pressure is 8MPa to obtain silicon nitride ceramics with complex shapes.

The solidification depth and density of the silicon nitride ceramics of the above Examples 1-6 and Comparative Examples were tested, and the results are shown in Table 1.

The test result of table 1 embodiment 1-6 and comparative example

sample Curing Depth (microns) Density (%) comparative example 20 92 Example 1 twenty two 95 Example 2 twenty two 97 Example 3 twenty four 85 Example 4 25 85 Example 5 35 80 Example 6 27 82

From Table 1, it can be seen from Examples 1-6 and Comparative Examples that coating silicon nitride with sintering aids on the surface of silicon nitride by chemical precipitation can effectively improve the performance of silicon nitride ceramic slurry in the photocuring process. The thickness of single-layer curing can ensure the bonding force between layers. In addition, a suitable coating process helps to increase the density, and the coating process effectively improves the dispersion of the sintering aid in the silicon nitride powder; it can be seen from Examples 1-6 that the concentration of each sintering aid is When the concentration is 0.01-0.04mol/L, the solidification depth and density of silicon nitride ceramics are superior.

The above description is only the preferred embodiment of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present application, some improvements and modifications can also be made. These improvements and modifications are also It should be regarded as the protection scope of this application.

Claims (10)

1. a preparation method of light-cured silicon nitride ceramic slurry, is characterized in that, comprises the following steps: Step 1, mixing the silicon nitride powder solution, the sintering aid solution, the first dispersant and the precipitating agent to obtain a precipitating solution, and filtering the precipitating solution to obtain a mixed solid; Step 2. After cleaning the mixed solid, calcining and ball milling, the coated powder is obtained; Step 3, mixing the coating powder, photocurable resin, photoinitiator and second dispersant to obtain photocurable silicon nitride ceramic slurry. 2 . The method for preparing photocurable silicon nitride ceramic slurry according to claim 1 , wherein the silicon nitride powder in the silicon nitride powder solution has a particle size of 0.2-1 μm. 3. The method for preparing photocurable silicon nitride ceramic slurry according to claim 1, characterized in that the concentration of the silicon nitride powder solution is 0.1-1mol/L. 4. the preparation method of light-cured silicon nitride ceramic slurry according to claim 1, is characterized in that, described sintering aid solution comprises aluminum chloride hexahydrate solution, aluminum nitrate nonahydrate solution, yttrium nitrate hexahydrate solution , one or more of magnesium chloride hexahydrate and magnesium nitrate hexahydrate. 5. The method for preparing photocurable silicon nitride ceramic slurry according to claim 1, characterized in that the concentration of the sintering aid solution is 0.01-0.5 mol/L. 6. The preparation method of light-cured silicon nitride ceramic slurry according to claim 1, characterized in that, the precipitating agent comprises one of NaOH, KOH, NH ₃ ·H ₂ O and CO(NH ₂ ) ₂ one or more species. 7. The method for preparing photocured silicon nitride ceramic slurry according to claim 1, characterized in that the pH value of the precipitation solution is 8-12. 8. A silicon nitride ceramic slurry, characterized in that it is prepared by the method for preparing a light-cured silicon nitride ceramic slurry according to any one of claims 1 to 7. 9. A method for preparing silicon nitride ceramics, comprising the following steps: Step 1, the light-cured silicon nitride ceramic slurry prepared by the preparation method of the light-curable silicon nitride ceramic slurry as claimed in any one of claims 1 to 6 or the light-cured silicon nitride ceramic slurry as claimed in claim 7 Silicon ceramic slurry is used as the raw material, and solidified layer by layer is superimposed according to the slice outline of the part drawing to obtain a molded green body; Step 2, debinding and sintering the molded green body to obtain silicon nitride ceramics. 10. A silicon nitride ceramic, characterized in that it is obtained by the preparation method of the silicon nitride ceramic as claimed in claim 9.