CN112794721A - Preparation method of silicon nitride particles - Google Patents

Preparation method of silicon nitride particles Download PDF

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CN112794721A
CN112794721A CN202110032844.4A CN202110032844A CN112794721A CN 112794721 A CN112794721 A CN 112794721A CN 202110032844 A CN202110032844 A CN 202110032844A CN 112794721 A CN112794721 A CN 112794721A
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silicon nitride
silica sol
reaction
nitride particles
temperature
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CN112794721B (en
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王志江
戴丁
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Harbin Institute of Technology
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
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    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3418—Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
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    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/46—Gases other than oxygen used as reactant, e.g. nitrogen used to make a nitride phase

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  • Ceramic Engineering (AREA)
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Abstract

A preparation method of silicon nitride particles relates to a preparation method of silicon nitride. The invention aims to solve the problems of high production cost, complex process and difficult industrialization of the existing silicon nitride particles. The preparation method comprises the following steps: firstly, preparing precursor powder; secondly, sintering reaction; and thirdly, carbon removal treatment. The method is used for preparing the silicon nitride particles.

Description

Preparation method of silicon nitride particles
Technical Field
The invention relates to a preparation method of silicon nitride.
Background
The silicon nitride ceramic has high strength, high hardness, abrasion resistance, oxidation resistance and good thermal shock resistance, and is an ideal high-temperature structural material. Meanwhile, the silicon nitride is a novel functional ceramic material, has good chemical stability, ideal high thermal conductivity and good insulativity, and can be used as a heat-conducting filler or a substrate of an integrated circuit; silicon nitride has good high-temperature dielectric property and thermal shock resistance, so that the silicon nitride is widely used as an antenna housing material for airplanes and missiles. The excellent performance of the silicon nitride makes the silicon nitride widely applied to the fields of aerospace, mechanical engineering, communication, electronics and the like.
There are many methods for preparing silicon nitride, which can be generally divided into three major groups, namely solid-phase reaction method, liquid-phase reaction method and gas-phase reaction method, and the main methods are: direct nitridation, carbothermal reduction, thermal decomposition, self-propagating, sol-gel, and plasma methods. In the synthesis process, because the typical morphology of the silicon nitride is columnar, the silicon nitride is more prone to form a one-dimensional morphology, the synthesis of spherical particles is difficult, and the spherical particles have higher fluidity and are the morphology most suitable for the high-thermal-conductivity filler. The prior methods for preparing the silicon nitride particles mainly comprise a sol-gel method and a plasma method, but the two methods have the defects of high equipment requirement, high cost, complex process, difficult industrial production and the like.
Disclosure of Invention
The invention provides a preparation method of silicon nitride particles, aiming at solving the problems of high production cost, complex process and difficult industrialization of the existing silicon nitride particles.
A preparation method of silicon nitride particles is completed according to the following steps:
firstly, preparing precursor powder:
dissolving an additive and a carbon source in silica sol, magnetically stirring for 2-10 h at the rotating speed of a stirrer of 100-600 r/min, drying for 2-24 h at the temperature of 40-100 ℃ after uniformly stirring, taking out after drying, and crushing uniformly to obtain precursor powder;
the mass of the additive is 0.1-50% of the mass of the silica sol; the mass ratio of the carbon source to the silica sol is 1 (1-8);
secondly, sintering reaction:
spreading precursor powder at the bottom of a graphite crucible, then placing the graphite crucible into a tubular furnace, introducing nitrogen as reaction gas, controlling the flow rate of the nitrogen to be 0.05-2L/min, then carrying out sintering reaction for 0.5-24 h at the sintering reaction temperature of 1200-1800 ℃, and cooling to room temperature after the reaction is finished to obtain sintered powder;
thirdly, carbon removal treatment:
placing the sintered powder in a muffle furnace, performing decarbonization treatment for 0.5-10 h at the decarbonization reaction temperature of 200-1000 ℃, and naturally cooling to room temperature to obtain the silicon nitride particles.
The invention has the beneficial effects that:
1. the invention develops a simple method for preparing the silicon nitride particle material, and the method has the advantages of low price of raw materials, simple process, low cost and large-scale production.
2. The silicon nitride powder prepared by the invention has high purity (alpha-Si)3N4The phase can reach 95-98 percent), has regular appearance, better dispersity and fluidity, can be used as high-quality powder to prepare high-performance silicon nitride ceramics, and is also an ideal high-heat-conducting filler.
The invention is used for a preparation method of silicon nitride particles.
Drawings
FIG. 1 is an XRD spectrum, 1 is silicon nitride particles prepared in the first example, 2 is alpha-Si3N4Standard card PDF #74-0554 of facies;
FIG. 2 is an SEM image of silicon nitride particles prepared according to the first example;
FIG. 3 is an XRD spectrum, 1 is the silicon nitride particles prepared in example two, and 2 is alpha-Si3N4PDF # 76-1408;
FIG. 4 is an SEM image of silicon nitride particles prepared in example two.
Detailed Description
The first embodiment is as follows: the preparation method of the silicon nitride particles of the embodiment is completed according to the following steps:
firstly, preparing precursor powder:
dissolving an additive and a carbon source in silica sol, magnetically stirring for 2-10 h at the rotating speed of a stirrer of 100-600 r/min, drying for 2-24 h at the temperature of 40-100 ℃ after uniformly stirring, taking out after drying, and crushing uniformly to obtain precursor powder;
the mass of the additive is 0.1-50% of the mass of the silica sol; the mass ratio of the carbon source to the silica sol is 1 (1-8);
secondly, sintering reaction:
spreading precursor powder at the bottom of a graphite crucible, then placing the graphite crucible into a tubular furnace, introducing nitrogen as reaction gas, controlling the flow rate of the nitrogen to be 0.05-2L/min, then carrying out sintering reaction for 0.5-24 h at the sintering reaction temperature of 1200-1800 ℃, and cooling to room temperature after the reaction is finished to obtain sintered powder;
thirdly, carbon removal treatment:
placing the sintered powder in a muffle furnace, performing decarbonization treatment for 0.5-10 h at the decarbonization reaction temperature of 200-1000 ℃, and naturally cooling to room temperature to obtain the silicon nitride particles.
The principle is as follows: during the formation of silicon nitride, the following chemical reactions may occur in the system:
SiO2(s)+Si(s)＝2SiO(g) (1)
SiO2(s)+C(s)＝SiO(g)+CO(g) (2)
3SiO(g)+3CO(s)+2N2(g)＝Si3N4(s)+3CO2(g) (3)
SiO(g)+3CO(g)＝SiC(s)+2CO2(g) (4)
in the absence of additives, SiO2The intermediate formed by reaction with C may react to form SiC, or with N2Reaction to form Si3N4Of SiC with Si3N4The generation of (2) is a competitive relationship, and meanwhile, silicon nitride is more prone to obtain the shapes of prisms, whiskers and the like in the synthesis process, and only a plasma method is easy to obtain silicon nitride particles, but the plasma method is high in cost and limits the development of the silicon nitride particles. In order to obtain silicon nitride particles with higher purity, additives are added to inhibit the generation of SiC and control the generation morphology of silicon nitride. After addition of additives such as NaF, a liquid phase of Na-Si-O-F may form during the reaction, followed by N2Na-Si-O-F-N liquid is formed after diffusion, silicon nitride is separated out when the liquid is saturated, spheres with the minimum surface energy tend to be formed better with the help of the liquid, and NaF is evaporated through the following reaction without further impurity removal treatment.
4NaF(s)+SiO2(s)＝SiF4(g)+2Na2O(s) (5)
Na2O(s)+C(s)＝2Na(g)+CO(g) (6)
The beneficial effects of the embodiment are as follows:
1. the embodiment develops a simple method for preparing the silicon nitride particle material, and the method has the advantages of low price of raw materials, simple process, low cost and capability of large-scale production.
2. The silicon nitride powder prepared by the embodiment has high purity (alpha-Si)3N4The phase can reach 95-98 percent), has regular appearance, better dispersity and fluidity, can be used as high-quality powder to prepare high-performance silicon nitride ceramics, and is also an ideal high-heat-conducting filler.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the carbon source in the step one is carbon black or activated carbon. The rest is the same as the first embodiment.
The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: the additive in the step one is NaF, KF, CaF or NaCl. The other is the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: SiO in silica sol described in step one2The mass percentage of the component (A) is 20-50%, and the viscosity is less than or equal to 25 mPas. The others are the same as the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: the mass of the additive in the first step is 2-5% of the mass of the silica sol. The rest is the same as the first to fourth embodiments.
The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: the mass ratio of the carbon source to the silica sol in the first step is 1 (4-8). The rest is the same as the first to fifth embodiments.
The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: dissolving the additive and a carbon source in silica sol, magnetically stirring for 4-10 h at the rotation speed of a stirrer of 250-600 r/min, drying for 12-24 h at the temperature of 80-100 ℃ after uniformly stirring, taking out after drying, and crushing uniformly to obtain precursor powder. The others are the same as the first to sixth embodiments.
The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: and introducing nitrogen as reaction gas in the second step, and controlling the flow rate of the nitrogen to be 0.1L/min-2L/min. The rest is the same as the first to seventh embodiments.
The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: and in the second step, the sintering reaction is carried out for 2 to 24 hours at the sintering reaction temperature of 1550 to 1800 ℃. The other points are the same as those in the first to eighth embodiments.
The detailed implementation mode is ten: the present embodiment differs from one of the first to ninth embodiments in that: in the third step, under the condition that the decarbonization reaction temperature is 700-1000 ℃, the decarbonization treatment is carried out for 2-10 h. The other points are the same as those in the first to ninth embodiments.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
a preparation method of silicon nitride particles is completed according to the following steps:
firstly, preparing precursor powder:
dissolving 0.058g of additive and 0.72g of carbon source in 2.88g of silica sol, magnetically stirring for 4 hours at the rotating speed of a stirrer of 250r/min, drying for 12 hours at the temperature of 80 ℃ after uniform stirring, taking out after drying, and crushing to be uniform to obtain precursor powder;
secondly, sintering reaction:
flatly paving precursor powder at the bottom of a graphite crucible, then placing the graphite crucible into a tube furnace, introducing nitrogen as reaction gas, controlling the flow rate of the nitrogen to be 0.1L/min, then carrying out sintering reaction for 2h at the sintering reaction temperature of 1550 ℃, and cooling to room temperature after the reaction is finished to obtain sintered powder;
thirdly, carbon removal treatment:
and placing the sintered powder in a muffle furnace, performing decarbonization treatment for 2 hours at the decarbonization reaction temperature of 700 ℃, and naturally cooling to room temperature to obtain the silicon nitride particles.
The carbon source in the step one is carbon black.
The additive in the step one is NaF.
SiO in silica sol described in step one2The mass percentage of the component (A) is 30 percent, and the viscosity is less than or equal to 7 mPas.
FIG. 1 is an XRD spectrum, 1 is silicon nitride particles prepared in the first example, 2 is alpha-Si3N4Standard card PDF #74-0554 of facies; by comparing with the standard card, the peak in XRD and the alpha-Si of the standard card PDF #74-0554 can be known3N4The phase is basically consistent, and the main phase of the material prepared by the embodiment is proved to be alpha-Si3N4The purity was about 98%.
FIG. 2 is an SEM image of silicon nitride particles prepared according to the first example; as can be seen from the figure, the silicon nitride material prepared in this example has a microscopic morphology of particles with a diameter of about 280 nm.
Example two:
the difference between the present embodiment and the first embodiment is: the amount of NaF added in step one was 0.144 g. The rest is the same as the first embodiment.
FIG. 3 is an XRD spectrum, 1 is the silicon nitride particles prepared in example two, and 2 is alpha-Si3N4PDF # 76-1408; by comparing with the standard card, the peak in XRD and the alpha-Si of the standard card PDF #76-1408 can be known3N4The phase is basically consistent, and the main phase of the silicon nitride particles prepared by the embodiment is proved to be alpha-Si3N4The purity was about 95%.
FIG. 4 is an SEM image of silicon nitride particles prepared in example two; as can be seen from the figure, the silicon nitride material prepared in the present embodiment has a microscopic morphology of particles with a diameter of about 150 nm.

Claims (10)

1. A preparation method of silicon nitride particles is characterized by comprising the following steps:
firstly, preparing precursor powder:
dissolving an additive and a carbon source in silica sol, magnetically stirring for 2-10 h at the rotating speed of a stirrer of 100-600 r/min, drying for 2-24 h at the temperature of 40-100 ℃ after uniformly stirring, taking out after drying, and crushing uniformly to obtain precursor powder;
the mass of the additive is 0.1-50% of the mass of the silica sol; the mass ratio of the carbon source to the silica sol is 1 (1-8);
secondly, sintering reaction:
spreading precursor powder at the bottom of a graphite crucible, then placing the graphite crucible into a tubular furnace, introducing nitrogen as reaction gas, controlling the flow rate of the nitrogen to be 0.05-2L/min, then carrying out sintering reaction for 0.5-24 h at the sintering reaction temperature of 1200-1800 ℃, and cooling to room temperature after the reaction is finished to obtain sintered powder;
thirdly, carbon removal treatment:
placing the sintered powder in a muffle furnace, performing decarbonization treatment for 0.5-10 h at the decarbonization reaction temperature of 200-1000 ℃, and naturally cooling to room temperature to obtain the silicon nitride particles.
2. The method according to claim 1, wherein the carbon source in the first step is carbon black or activated carbon.
3. The method according to claim 1, wherein the additive in the first step is NaF, KF, CaF or NaCl.
4. The method according to claim 1, wherein the SiO in the silica sol is in the first step2The mass percentage of the component (A) is 20-50%, and the viscosity is less than or equal to 25 mPas.
5. The method according to claim 1, wherein the additive is present in an amount of 2-5% by mass based on the mass of the silica sol.
6. The method according to claim 1, wherein the mass ratio of the carbon source to the silica sol in the first step is 1 (4-8).
7. The method according to claim 1, wherein the additive and the carbon source are dissolved in the silica sol, the mixture is magnetically stirred for 4 to 10 hours at a stirrer rotation speed of 250 to 600r/min, the mixture is dried for 12 to 24 hours at a temperature of 80 to 100 ℃ after being uniformly stirred, and the dried mixture is taken out and pulverized uniformly to obtain the precursor powder.
8. The method for preparing silicon nitride particles according to claim 1, wherein nitrogen is introduced as a reaction gas in the second step, and the flow rate of nitrogen is controlled to be 0.1L/min to 2L/min.
9. The method according to claim 1, wherein the sintering reaction temperature in step two is 1550 ℃ to 1800 ℃ for 2h to 24 h.
10. The method of claim 1, wherein the decarbonization reaction is carried out at a temperature of 700 ℃ to 1000 ℃ for 2h to 10 h.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58104006A (en) * 1981-12-11 1983-06-21 Central Glass Co Ltd Preparation of silicon nitride powder
CN101353160A (en) * 2008-09-09 2009-01-28 辽宁工业大学 Synthetic method of silicon nitride nanopowder
CN105776158A (en) * 2015-09-14 2016-07-20 天津纳德科技有限公司 Method for directly preparing high-sphericity silicon nitride powder by adopting high atmospheric pressure and additives
TWI646045B (en) * 2017-12-05 2019-01-01 國家中山科學研究院 A method for producing the spherical silicon nitride powder

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS58104006A (en) * 1981-12-11 1983-06-21 Central Glass Co Ltd Preparation of silicon nitride powder
CN101353160A (en) * 2008-09-09 2009-01-28 辽宁工业大学 Synthetic method of silicon nitride nanopowder
CN105776158A (en) * 2015-09-14 2016-07-20 天津纳德科技有限公司 Method for directly preparing high-sphericity silicon nitride powder by adopting high atmospheric pressure and additives
TWI646045B (en) * 2017-12-05 2019-01-01 國家中山科學研究院 A method for producing the spherical silicon nitride powder

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李懋强: "《热学陶瓷 性能测试工艺》", 30 June 2013, 中国建材工业出版社 *
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陈宏: "纳米Si3N4粉末制备技术及研究", 《中国优秀硕士学位论文全文数据库·工程科技Ⅰ辑》 *

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