阅读说明：本技术 一种仿生氮化硅陶瓷材料及其制备方法 (Bionic silicon nitride ceramic material and preparation method thereof ) 是由 林智杰 孙旭东 曾一明 赵睿宁 杨宏伟 陈家林 戴品强 田君 常发 洪春福 陈洪 于 2020-05-21 设计创作，主要内容包括：本发明公开了无机陶瓷材料技术领域的一种仿生氮化硅陶瓷材料及其制备方法,该种仿生氮化硅陶瓷材料的原料包括：β氮化硅晶须晶种；α氮化硅颗粒粉末；分散剂；粘结剂；塑化剂；溶剂,所述β氮化硅晶须直径为10～1000nm,长径比为4：1～100：1,所述α氮化硅颗粒粒径为0.01～10微米,氮化硅原料中β氮化硅晶须晶种占比5～50wt％,该种仿生氮化硅陶瓷材料及其制备方法,该方法以晶须定向增强薄膜为基元,提高基元的强度,薄层层叠形成陶瓷的氮化硅陶瓷材料,通过仿生人骨结构,溅射助剂形成梯度助剂,保证层状结构的形成,形成层状结构后,提高氮化硅陶瓷的强度和韧性。(The invention discloses a bionic silicon nitride ceramic material and a preparation method thereof in the technical field of inorganic ceramic materials, wherein the bionic silicon nitride ceramic material comprises the following raw materials: beta silicon nitride crystal whisker seed; alpha silicon nitride particle powder; a dispersant; a binder; a plasticizer; the silicon nitride crystal whisker is characterized by comprising a solvent, wherein the diameter of the silicon nitride crystal whisker is 10-1000 nm, and the length-diameter ratio is 4: 1-100: the grain size of the alpha silicon nitride particles is 0.01-10 micrometers, beta silicon nitride crystal whisker in a silicon nitride raw material accounts for 5-50 wt%, the bionic silicon nitride ceramic material and the preparation method thereof are characterized in that the method takes a whisker oriented reinforced film as a basic element to improve the strength of the basic element, thin layers are laminated to form the ceramic silicon nitride ceramic material, a gradient auxiliary agent is formed by a bionic human bone structure and a sputtering auxiliary agent to ensure the formation of a layered structure, and the strength and the toughness of the silicon nitride ceramic are improved after the layered structure is formed.)

1. A bionic silicon nitride ceramic material is characterized in that: the bionic silicon nitride ceramic material has a layered structure, the interior of each layer is reinforced by the directional arrangement of beta silicon nitride whiskers generated in situ, and the included angle of the arrangement directions of the whiskers between adjacent layers is not less than 10 degrees.

2. The biomimetic silicon nitride ceramic material according to claim 1, wherein: the bionic silicon nitride ceramic material comprises the following raw materials:

beta silicon nitride crystal whisker seed;

alpha silicon nitride particle powder;

a dispersant;

a binder;

a plasticizer;

a solvent.

3. The biomimetic silicon nitride ceramic material according to claim 2, wherein: the diameter of the beta silicon nitride crystal whisker is 10-1000 nm, and the length-diameter ratio is 4: 1-100: 1.

4. the biomimetic silicon nitride ceramic material according to claim 2, wherein: the grain diameter of the alpha silicon nitride particles is 0.01-10 microns, and beta silicon nitride crystal whisker seeds in the silicon nitride raw material account for 5-50 wt%.

5. The biomimetic silicon nitride ceramic material according to claim 2, wherein: the dispersing agent comprises but is not limited to ammonium citrate, ammonium persulfate, tetraethyl ethylenediamine, ammonium acrylate, polyvinylpyrrolidone, polyetherimide, glycerol trioleate, phosphate, castor oil, herring oil, ascorbic acid and terpineol, wherein the adding proportion of the dispersing agent is 0.01-2% of the slurry.

6. The biomimetic silicon nitride ceramic material according to claim 2, wherein: the binder comprises but is not limited to one or a mixture of more of cellulose, polyvinyl alcohol, polypropylene glycol, polyvinyl acetate, polyacrylic acid, acrylate, polyvinyl butyral and polymethyl methacrylate, and the adding proportion of the binder is 0.5-10% of the slurry.

7. The biomimetic silicon nitride ceramic material according to claim 2, wherein: the plasticizer comprises but is not limited to dibutyl phthalate, polyethylene glycol, polyacrylate and dibutyl sebacate, and the adding proportion is 1-20% of the slurry.

8. The biomimetic silicon nitride ceramic material according to claim 2, wherein: the solvent comprises but is not limited to deionized water, n-ethane, ethanol, acetone, butanone, butanol, ethylene glycol, glycerol, toluene, benzene, pentanol and xylene, and the adding proportion is 10-80% of the slurry.

9. A method for preparing a biomimetic silicon nitride ceramic material according to any of claims 1-8, wherein: the preparation method of the bionic silicon nitride ceramic material comprises the following steps:

the method comprises the following steps: placing the slurry obtained by ball milling into a vacuum defoaming machine, stirring and defoaming for 10-120 minutes, and then carrying out tape casting with a directional field to obtain a raw material with silicon nitride whisker crystal seeds qualitatively arranged, wherein the ball milling time is 0.1-48 hours, and the ball-to-material ratio is 1: 4-20: 1, the solid content of the silicon nitride ceramic in the slurry is 5-60%, the directional field refers to an external field for inducing the silicon nitride whiskers to be directionally arranged, and the external field includes but is not limited to one or a mixture of a strain field, a magnetic field and an electric field, and the external field application mode can be as follows: applying a 4-20T parallel magnetic field in a direction parallel to the casting direction, or forming a strain field by a scraper with a tooth comb structure, wherein the thickness of the raw material is 0.1-1000 microns;

step two: cutting the raw material into small pieces, and sputtering or spraying a sintering aid on the surface of the small pieces, wherein the longest side of each small piece is 1-30 mm in size, and the sintering aid comprises but is not limited to MgSi₂、MgSiN、TiSi₂、TaSi₂、MoSi₂And WSi₂One or a mixture of several of them;

step three: staggered stacking of small silicon nitride raw material elements in a graphite mold, degumming and hot-pressing or discharging plasma sintering in a nitrogen atmosphere to obtain layered silicon nitride closed-cell ceramic, wherein the degumming temperature is 300-600 ℃ and the time is 0.5-12 hours, the staggered stacking means that the arrangement direction of oriented whiskers in adjacent silicon nitride raw material small elements is 10-90 ℃, the hot-pressing or discharging plasma sintering is 1200-1600 ℃, the pressure is 20-90 MPa, and the sintering time is 0.5-6 hours;

step four: and (3) transferring the layered silicon nitride closed-pore ceramic into a hot isobaric sintering furnace or a gas pressure sintering furnace, sintering for 1-12 hours at 1600-2000 ℃ and 1-200 MPa of nitrogen gas pressure to fully densify the ceramic, and enabling the alpha silicon nitride to attach beta phase crystal seeds to perform phase change to form directionally arranged columnar beta silicon nitride whiskers.

Technical Field

The invention relates to the technical field of inorganic ceramic materials, in particular to a bionic silicon nitride ceramic material and a preparation method thereof.

Background

China firstly enters a 5G commercial era, meanwhile, a 6G research and development track is entered in a dispute form of each large-reaching country and multinational enterprises, and communication speed is increased by improving signal transmission frequency. The high-frequency PCB is a basic element comprising a radio frequency front end and a filter element, and is formed by constructing a circuit on an insulating substrate by using noble metal electronic paste. In the background of high-frequency application, the requirement for reducing transmission loss is more urgent, and the high-frequency ceramic substrate has the advantages of small dielectric loss and small thermal resistance, and can be matched with a high-conductivity noble metal circuit to form a PCB circuit board, so that signal loss can be avoided, the stability of elements can be improved, and the service life can be prolonged. Compared with the traditional alumina and aluminum nitride ceramic substrate, the silicon nitride has excellent toughness and strength, and is particularly suitable for application scenes of new energy vehicles, high-speed rails, cross-country armors and the like which need to bear jolt and cold-hot alternation.

Although China is leading the world in the aspect of 5G technology, in the field of high-frequency ceramic substrates, a large amount of import is still relied on, and national enterprises do not form climate.

A few domestic enterprises form a certain scale in the field of heat-conducting ceramic substrates, but are still laggard in scale and yield. The international high-frequency ceramic substrate market is basically monopolized by foreign suppliers. In the application fields of car networking, internet of things and the like, the research and development of high-strength and high-toughness silicon nitride ceramics are still difficult internationally, and substrate cracks and circuit falling caused by insufficient toughness are the key factors of the current similar products for influencing the service life of the substrate.

Disclosure of Invention

The invention aims to provide a bionic silicon nitride ceramic material and a preparation method thereof, which aim to solve the problem that the existing few domestic enterprises in the background technology form a certain scale in the field of heat-conducting ceramic substrates, but are still laggard in scale and yield. The international high-frequency ceramic substrate market is basically monopolized by foreign suppliers. In the application fields of car networking, internet of things and the like, the research and development of high-strength and high-toughness silicon nitride ceramics are still difficult internationally, and substrate cracks and circuit falling caused by insufficient toughness are the key problems that the service life of the substrate is influenced by the current similar products.

The invention provides the following technical scheme: the bionic silicon nitride ceramic material has a layered structure, beta silicon nitride whiskers generated in situ are directionally arranged and strengthened in each layer, and the included angle between the arrangement directions of the whiskers between adjacent layers is not less than 10 degrees.

A bionic silicon nitride ceramic material and a preparation method thereof are disclosed, the bionic silicon nitride ceramic material comprises the following raw materials:

beta silicon nitride crystal whisker seed;

alpha silicon nitride particle powder;

a dispersant;

a binder;

a plasticizer;

a solvent.

Preferably, the diameter of the beta silicon nitride whisker is 10-1000 nm, and the length-diameter ratio is 4: 1-100: 1.

preferably, the grain diameter of the alpha silicon nitride particles is 0.01-10 microns, and beta silicon nitride crystal whisker seeds in the silicon nitride raw material account for 5-50 wt%.

Preferably, the dispersant includes, but is not limited to, ammonium citrate, ammonium persulfate, tetraethyl ethylenediamine, ammonium acrylate, polyvinylpyrrolidone, polyetherimide, glycerol trioleate, phosphate ester, castor oil, herring oil, ascorbic acid and terpineol, and the addition ratio is 0.01-2% of the slurry.

Preferably, the binder comprises but is not limited to one or a mixture of more of cellulose, polyvinyl alcohol, polyvinyl acetate, polyacrylic acid, acrylate, polyvinyl butyral and polymethyl methacrylate, and the adding proportion is 0.5-10% of the slurry.

Preferably, the plasticizer includes, but is not limited to, dibutyl phthalate, polyethylene glycol, polyacrylate and dibutyl sebacate, and the addition ratio is 1-20% of the slurry.

Preferably, the solvent includes, but is not limited to, deionized water, n-ethane, ethanol, acetone, butanone, butanol, ethylene glycol, glycerol, toluene, benzene, pentanol, and xylene, and the addition ratio is 10-80% of the slurry.

A preparation method of a bionic silicon nitride ceramic material comprises the following steps:

the method comprises the following steps: placing the slurry obtained by ball milling into a vacuum defoaming machine, stirring and defoaming for 10-120 minutes, and then carrying out tape casting with a directional field to obtain a raw material with silicon nitride whisker crystal seeds qualitatively arranged, wherein the ball milling time is 0.1-48 hours, and the ball-to-material ratio is 1: 4-20: 1, the solid content of the silicon nitride ceramic in the slurry is 5-60%; the directional field refers to an external field for inducing the silicon nitride whiskers to be directionally arranged, and includes but is not limited to one or a mixture of a strain field, a magnetic field and an electric field; external field application modes include, but are not limited to: applying a 4-20T parallel magnetic field in a direction parallel to the casting direction, or forming a strain field by a scraper with a tooth comb structure, wherein the thickness of the raw material is 0.1-1000 microns;

step two: cutting the raw material into small pieces, and sputtering or spraying a sintering aid on the surface of the small pieces, wherein the longest side of each small piece is 1-30 mm in size, and the sintering aid comprises but is not limited to MgSi₂、MgSiN、TiSi₂、TaSi₂、MoSi₂And WSi₂One or a mixture of several of them;

step three: staggered stacking of small silicon nitride raw material elements in a graphite mold, degumming and hot-pressing or discharging plasma sintering in a nitrogen atmosphere to obtain layered silicon nitride closed-cell ceramic, wherein the degumming temperature is 300-600 ℃ and the time is 0.5-12 hours, the staggered stacking means that the arrangement direction of oriented whiskers in adjacent silicon nitride raw material small elements is 10-90 ℃, the hot-pressing or discharging plasma sintering is 1200-1600 ℃, the pressure is 20-90 MPa, and the sintering time is 0.5-6 hours;

step four: and (3) transferring the layered silicon nitride closed-pore ceramic into a hot isobaric sintering furnace or a gas pressure sintering furnace, sintering for 1-12 hours at 1600-2000 ℃ and 1-200 MPa of nitrogen gas pressure to fully densify the ceramic, and enabling the alpha silicon nitride to attach beta phase crystal seeds to perform phase change to form directionally arranged columnar beta silicon nitride whiskers.

Compared with the prior art, the invention has the beneficial effects that: the method comprises the following steps of mixing beta-phase silicon nitride whisker crystal seeds and alpha-phase silicon nitride particles, and enabling alpha-phase to attach to beta-phase silicon nitride whisker seeds which are arranged in an oriented mode to generate phase change through hot isostatic pressing, wherein on one hand, the strength is improved through in-situ reaction, on the other hand, columnar beta-phase silicon nitride whiskers generated through phase change inherit the oriented arrangement of the crystal seeds, and the elements are enhanced through a whisker oriented arrangement mode; cutting the raw material formed by tape casting to form small elementary elements, and then laminating, rearranging and sintering to form layered silicon nitride ceramic taking whisker directionally-reinforced silicon nitride as the elementary elements, wherein the layered silicon nitride ceramic has the characteristics of high strength and high toughness; the addition of the auxiliary agent by sputtering or spraying forms a gradient auxiliary agent layer in sintering, which promotes sintering on one hand and can protect the layered structure from being damaged on the other hand.

Drawings

FIG. 1 is a schematic top view of microstructural features of a silicon nitride ceramic made in accordance with the present invention;

FIG. 2 is a schematic front view of the microstructure characteristics of the silicon nitride ceramic prepared according to the present invention.

Detailed Description