阅读说明：本技术 一种痕量原位碳诱导的Si3N4导热陶瓷材料及制备方法 (Trace in-situ carbon-induced Si3N4Heat-conducting ceramic material and preparation method thereof ) 是由 银锐明 李鹏飞 王雨铮 刘为扬 谢南卿 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种痕量原位碳诱导的Si-(3)N-(4)导热陶瓷材料的制备方法,以Si-(3)N-(4)粉末、烧结助剂和有机物为原料,经改性、成型、一次烧结和二次烧结制备而成；通过有机物在一定温度下原位生成高活性、高均匀、可调控的痕量碳实现在氮化硅基体中原位分布,达到对晶界处氧脱除,减少玻璃相、提高α→β相转变率,解决直接添加碳时由于分布不均易引起坯体变形开裂、晶格氧去除效果有限、组织不均匀等问题,提高Si-(3)N-(4)导热陶瓷材料的导热性能和强度。(The invention discloses trace in-situ carbon-induced Si 3 N 4 Method for preparing heat-conducting ceramic material from Si 3 N 4 The powder, the sintering aid and the organic matter are used as raw materials and are prepared by modification, molding, primary sintering and secondary sintering; the organic matter generates high-activity, high-uniformity and controllable trace carbon in situ at a certain temperature to realize in-situ distribution in a silicon nitride matrix, thereby removing oxygen at a crystal boundary, reducing a glass phase, improving the alpha → beta phase transformation rate, and solving the problem that a blank is easy to cause due to uneven distribution when the carbon is directly addedThe problems of body deformation and cracking, limited crystal lattice oxygen removal effect, uneven structure and the like are solved, and Si is improved 3 N 4 The heat conducting property and the strength of the heat conducting ceramic material.)

1. Trace in-situ carbon-induced Si₃N₄The preparation method of the heat-conducting ceramic material is characterized by comprising the following steps:

s1, modification: mixing Si₃N₄Acid washing the powder in acid solution to remove impurity oxide, ball milling, aging and drying the powder in alkaline solution together with sintering aid to obtain modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding an organic matter into the mixed powder obtained in the step S1, uniformly mixing, and then forming the mixture to obtain a blank;

s3, primary sintering: sintering the blank at the temperature of 200-1000 ℃ to degrease the blank and generate trace in-situ activated carbon;

s4, secondary sintering: carrying out hot-pressing sintering on the blank treated in the step S3 at 1700-1900 ℃, and realizing high length-diameter ratio and high beta-Si through trace in-situ activated carbon₃N₄Phase content and high densification to obtain Si₃N₄A thermally conductive ceramic material.

2. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the acidic solution in the step S1 comprises HNO₃、HCl、H₂SO₄And one or more of acetic acid, wherein the concentration of the acid solution is 2-5%.

3. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the alkaline solution in the step S1 comprises NaOH, KOH and ammonia water, and the concentration of the alkaline solution is 3-8%.

4. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the using amount of the organic matters in the step S2 is 2-8 wt%, and the organic matters comprise one or more of polyethylene glycol, rubber, polyethylene, polypropylene, polyvinyl alcohol, polyester, polyamide, polyacrylonitrile and the like.

5. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the forming process in the step S2 is any one of extrusion forming, compression forming or isostatic pressing forming.

6. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the step S3 further comprises a heat preservation process.

7. The trace in situ carbon induced Si according to claim 6₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the heat preservation process in the step S3 is at least twice.

8. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the content of the in-situ activated carbon generated in the step S3 is 0.1-1.0%.

9. The trace in situ carbon induced Si according to claim 1₃N₄The preparation method of the heat-conducting ceramic material is characterized in that the pressure in the step S4 of secondary sintering is 5-10 MPa.

10. Si obtained by the preparation method of any one of claims 1 to 9₃N₄A thermally conductive ceramic material.

Technical Field

The invention relates to the technical field of ceramic materials, in particular to trace in-situ carbon-induced Si₃N₄A heat-conducting ceramic material and a preparation method thereof.

Background

The 5G communication becomes the focus of a new round of competition in information leather of various countries in the 21 st century, and has urgent needs in the fields of aerospace, traffic, energy and the like. The integrated circuit of the communication equipment develops towards high frequency, high power, miniaturization and the like, but the high frequency causes serious signal transmission loss, the high power generates large amount of heat to easily cause circuit instability, and the integrated circuit bearing substrate is required to have the performances of high heat conductivity, high thermal vibration resistance, high toughness and the like. The silicon nitride has the characteristics of high hardness, high strength, small thermal expansion coefficient and the like, is chemically inert to metal at high temperature and has high fracture toughness, and becomes an attractive substrate material for the 5G communication field. The heat-conducting property and the dielectric loss characteristic of the silicon nitride are mainly determined by compactness, glass phase content, beta phase proportion, grain size and the like, and the trace carbon can promote crystallization of the glass phase, promote alpha → beta phase to densify, reduce lattice oxygen, further improve the heat conductivity of the material and reduce the dielectric loss.

The Chinese patent with application number of 2020101077487 discloses high-thermal-conductivity Si₃N₄Ceramics and process for their preparation, using Si₃N₄Powder and sintering aid Mg₂Preparation of Si from Si and C₃N₄Ceramics, annealed Si₃N₄The thermal conductivity of the ceramic is 110 W.m^-1·K^-1The Vickers hardness is 16.2-17.8GPa, and the bending strength is 753-846 MPa. The technical scheme improves Si₃N₄The ceramic material has mechanical property and thermal conductivity, but the carbon is easily distributed unevenly when being directly added, and the excessive addition can reduce the compactness and increase the loss value. Therefore, how to regulate the content and the uniform distribution of the trace carbon is one of the key points for realizing the high-frequency, low-loss, high-heat conduction and the commercialization of the silicon nitride.

Disclosure of Invention

The invention aims to provide trace in-situ carbon-induced Si aiming at the defects in the prior art₃N₄The preparation method of the heat-conducting ceramic material realizes Si by generating trace in-situ carbon in a ceramic blank₃N₄High length-diameter ratio and high beta-Si of heat-conducting ceramic material₃N₄Phase content and high densification.

Another object of the present invention is to provide Si obtained by the above-mentioned production method₃N₄A thermally conductive ceramic material.

The purpose of the invention is realized by the following technical scheme:

trace in-situ carbon-induced Si₃N₄The preparation method of the heat-conducting ceramic material comprises the following steps:

s1, modification: mixing Si₃N₄Acid washing the powder in acid solution to remove impurity oxide, ball milling, aging and drying the powder in alkaline solution together with sintering aid to obtain modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding an organic matter into the mixed powder obtained in the step S1, uniformly mixing, and then forming the mixture to obtain a blank;

s3, primary sintering: sintering the blank at the temperature of 200-1000 ℃ to degrease the blank and generate trace in-situ activated carbon;

s4, secondary sintering: carrying out hot-pressing sintering on the blank treated in the step S3 at 1700-1900 ℃, and realizing high length-diameter ratio and high beta-Si through trace in-situ activated carbon₃N₄Phase content and high densification to obtain Si₃N₄A thermally conductive ceramic material.

Further, the acidic solution in step S1 includes HNO₃、HCl、H₂SO₄And one or more of acetic acid, wherein the concentration of the acid solution is 2-5%.

Further, in the step S1, the alkaline solution includes NaOH, KOH, and ammonia water, and the concentration of the alkaline solution is 3-8%.

Further, the amount of the organic substance used in step S2 is 2-8 wt%, and the organic substance includes one or more of polyethylene glycol, rubber, polyethylene, polypropylene, polyvinyl alcohol, polyester, polyamide, polyacrylonitrile, and the like.

Further, the molding process in step S2 is any one of extrusion molding, press molding, or isostatic pressing.

Further, step S3 includes a heat preservation process.

Further, the heat-preserving process in step S3 is performed at least twice.

Further, the content of the in-situ activated carbon generated in the step S3 is 0.1-1.0%.

Further, the pressure at the time of secondary sintering in step S4 is 5-10 MPa.

Si obtained by the preparation method₃N₄A thermally conductive ceramic material.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, through impurity removal and activation treatment of raw materials, oxides which influence the heat conductivity of the raw materials in the original powder can be effectively removed, the surface energy and sintering activity of the powder can be improved, the material cost can be reduced, and the acid and alkali are further neutralized to reduce the environmental pollution.

The method realizes in-situ distribution in the silicon nitride matrix by utilizing the characteristics of high activity, high uniformity, adjustability and the like of in-situ trace carbon of organic matters at high temperature, thereby achieving the purposes of removing oxygen at a crystal boundary, reducing a glass phase, improving the alpha → beta phase transformation rate, and reducing the problems of deformation and cracking of a blank body, limited crystal lattice oxygen removal effect, uneven tissue and the like caused by uneven distribution of directly added carbon.

The method can effectively improve the heat-conducting property and the strength of the material, and the prepared Si₃N₄The density of the heat-conducting ceramic material is more than 98.5 percent, crystal grains are fibrous, the length-diameter ratio is more than 5:1, and the heat conductivity coefficient reaches 130-160 W.m^-1·K^-1The fracture toughness reaches 7-9 MPa.m^1/2The above.

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the following specific examples.

Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the present invention.

Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment and the like used in the present invention are commercially available or can be prepared by existing methods.

Example 1

This example provides a trace in situ carbon induced Si₃N₄The preparation method of the heat-conducting ceramic material specifically comprises the following steps:

s1, modification: mixing Si₃N₄Pickling the powder in an acidic solution of 3% HNO₃And HCl with a concentration of 3% in a 1:1 ratio, and then mixing the settled powder with a sintering aid (3 wt% Y)₂O₃And 5 wt% of MgO) in an alkaline solution, the alkaline solution is a 5% NaOH solution, and finally the powder is washed by deionized water and dried to obtain the modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding organic matter into the mixed powder obtained in step S1, wherein the amount of organic matter is (relative to Si)₃N₄Powder quality) 4 wt%, the organic matter is prepared by uniformly stirring 1 wt% of polyethylene glycol, 1.5 wt% of polyvinyl alcohol, 1 wt% of polyester and 0.5 wt% of polyamide according to the mass ratio; then, carrying out isostatic pressing on the mixture to obtain a blank;

s3, primary sintering: putting the blank body into a sintering furnace, heating at the speed of 3 ℃/min, and respectively preserving heat at 400 ℃ and 700 ℃ for 2 hours for pyrolysis to degrease the blank body and generate trace in-situ activated carbon, wherein the content of the in-situ activated carbon is 0.6 wt%;

s4, secondary sintering: carrying out hot-pressing sintering on the blank treated in the step S3 at 1750 ℃ for 2h and the pressure of 10MPa to obtain Si₃N₄Heat conductive ceramicsA material.

Example 2

This example provides a trace in situ carbon induced Si₃N₄The preparation method of the heat-conducting ceramic material specifically comprises the following steps:

s1, modification: mixing Si₃N₄Pickling the powder in an acidic solution of 4% HNO₃Solution, then mixing the settled powder with a sintering aid (3 wt% Y)₂O₃And 5 wt% MgO) in an alkaline solution of 8% NH, and aging₄OH solution, finally washing the powder by deionized water and drying to obtain modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding organic matter into the mixed powder obtained in step S1, and mixing uniformly, wherein the amount of the organic matter is the amount (relative to Si)₃N₄Powder quality) is 5 wt%, and the organic matter is prepared by uniformly stirring 1.5 wt% of polyethylene glycol, 1 wt% of polyacrylonitrile and 2.5 wt% of polyvinyl alcohol according to the mass ratio; then, carrying out isostatic pressing on the mixture through a soft film sheath to obtain a blank;

s3, primary sintering: putting the blank body into a sintering furnace, heating at the speed of 3 ℃/min, and respectively preserving heat for 2 hours at 350 ℃, 520 ℃ and 750 ℃ for pyrolysis to degrease the blank body and generate trace in-situ activated carbon, wherein the content of the in-situ activated carbon is 0.8 wt%;

s4, secondary sintering: carrying out hot-pressing sintering on the green body treated in the step S3 at 1890 ℃ for 2h and under the pressure of 8MPa to obtain Si₃N₄A thermally conductive ceramic material.

Example 3

This example provides a trace in situ carbon induced Si₃N₄The preparation method of the heat-conducting ceramic material specifically comprises the following steps:

s1, modification: mixing Si₃N₄Pickling the powder in an acidic solution of 4% HNO₃And HCl with a concentration of 3% in a 1:1 ratio, and then mixing the settled powder with a sintering aid (3 wt% Y)₂O₃And 5 wt% MgO) in an alkaline solutionBall milling and aging are carried out, an alkaline solution is a NaOH solution with the concentration of 4 percent, and finally the powder is washed by deionized water and dried to obtain the modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding organic matter into the mixed powder obtained in step S1, and mixing uniformly, wherein the amount of the organic matter is the amount (relative to Si)₃N₄Powder quality) is 5 wt%, and the organic matter is prepared by uniformly stirring 1.2 wt% of polyethylene glycol, 1.5 wt% of polyethylene and 1.3 wt% of polyamide according to the mass ratio; then, carrying out isostatic pressing on the mixture to obtain a blank;

s3, primary sintering: putting the blank into a sintering furnace, heating at the speed of 3 ℃/min, and respectively preserving heat for 2 hours at 300 ℃, 600 ℃ and 850 ℃ for pyrolysis to degrease the blank and generate trace in-situ activated carbon, wherein the content of the in-situ activated carbon is 0.7 wt%;

s4, secondary sintering: carrying out hot-pressing sintering on the blank treated in the step S3 at 1900 ℃ for 2h and the pressure of 10MPa to obtain Si₃N₄A thermally conductive ceramic material.

Example 4

S1, modification: mixing Si₃N₄The powder was pickled in an acidic solution of 3% HCl and the settled powder was then mixed with a sintering aid (3 wt% Y)₂O₃And 5 wt% of MgO) in an alkaline solution, the alkaline solution is an ammonia water solution with the concentration of 4%, and finally the powder is cleaned by deionized water and dried to obtain the modified Si₃N₄And sintering aid mixed powder;

s2, forming: adding organic matter into the mixed powder obtained in step S1, wherein the amount of organic matter is (relative to Si)₃N₄Powder mass) is 6 wt%, and the organic matter is prepared by uniformly stirring 2.5 wt% of polypropylene, 2.5 wt% of polyvinyl alcohol and 1 wt% of polyester according to the mass ratio; then, carrying out isostatic pressing on the mixture to obtain a blank;

s3, primary sintering: putting the blank into a sintering furnace, heating at the speed of 3 ℃/min, and respectively preserving heat for 2 hours at 400 ℃, 700 ℃ and 900 ℃ for pyrolysis to degrease the blank and generate trace in-situ activated carbon, wherein the content of the in-situ activated carbon is 0.4 wt%;

s4, secondary sintering: carrying out hot-pressing sintering on the blank treated in the step S3 at 1900 ℃ for 2h and the pressure of 10MPa to obtain Si₃N₄A thermally conductive ceramic material.

Si prepared in examples 1 to 4₃N₄The heat-conducting ceramic material is subjected to performance test, and the result is as follows:

it should be understood that the above examples are only for clearly illustrating the technical solutions of the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.