阅读说明：本技术 原位生成氮化铝-碳化硅固溶体复相陶瓷及其制备方法 (In-situ generated aluminum nitride-silicon carbide solid solution composite ceramic and preparation method thereof ) 是由 余超 郑永翔 邓承继 丁军 祝洪喜 吴欣欣 于 2020-06-09 设计创作，主要内容包括：一种原位生成氮化铝-碳化硅固溶体复相陶瓷及其制备方法。其技术方案是：将Al<Sub>4</Sub>SiC<Sub>4</Sub>粉末和粘结剂混合,在5～50MP条件下预压成型,于100～300MPa条件下等静压成型,在110℃烘干,得到预制坯体。将预制坯体装入石墨坩埚内,然后将所述石墨坩埚置于热压炉内,在≤0.1mbar条件下以5～10℃/min的速率从室温加热至1100～1200℃,在保温条件下充N<Sub>2</Sub>至2～10MPa,保压条件下以1～5℃/min的速率再加热至1900～2200℃,保压保温2～5h,自然冷却至室温,即得原位生成氮化铝-碳化硅固溶体复相陶瓷。本发明工艺简单和操作方便,制备的原位生成氮化铝-碳化硅固溶体复相陶瓷的密度低、质量轻、结构均匀致密、耐高温、抗氧化性能、抗水化性和强度高。(An in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic and a preparation method thereof. The technical scheme is as follows: mixing Al 4 SiC 4 Mixing the powder and the binder, pre-pressing and molding under the condition of 5-50 MP, isostatic pressing and molding under the condition of 100-300 MPa, and drying at 110 ℃ to obtain a prefabricated blank. Loading the prefabricated blank into a graphite crucible, then placing the graphite crucible into a hot pressing furnace, heating the graphite crucible from room temperature to 1100-1200 ℃ at the speed of 5-10 ℃/min under the condition of not more than 0.1mbar, and filling N under the condition of heat preservation 2 And (3) heating to 1900-2200 ℃ at the speed of 1-5 ℃/min under the pressure maintaining condition, maintaining the pressure and keeping the temperature for 2-5 h, and naturally cooling to room temperature to obtain the in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic. The invention has simple process and convenient operation, and the prepared in-situ generated nitridationThe aluminum-silicon carbide solid solution complex phase ceramic has the advantages of low density, light weight, uniform and compact structure, high temperature resistance, oxidation resistance, hydration resistance and high strength.)

1. A preparation method for generating aluminum nitride-silicon carbide solid solution multiphase ceramics in situ is characterized by comprising the following steps:

step one, according to Al₄SiC₄The mass ratio of the powder to the binder is 100: 2-5, and the Al is added₄SiC₄Mixing the powder and the binder to obtain a mixture;

the Al is₄SiC₄The purity of the powder is more than or equal to 98.0 wt%, and Al₄SiC₄The particle size of the powder is less than or equal to 150 mu m;

secondly, pre-pressing and molding the mixture under the condition of 5-50 MP, then carrying out isostatic pressing under the condition of 100-300 MPa, then placing the mixture in a constant-temperature drying box, and drying the mixture for 1-5 hours at the temperature of 110 ℃ to obtain a prefabricated blank body;

step three, the prefabricated blank body is placed into a graphite crucible, then the graphite crucible is placed into a hot pressing furnace, the graphite crucible is heated to 1100-1200 ℃ from room temperature at the speed of 5-10 ℃/min under the condition that the pressure is less than or equal to 0.1mbar, and N is filled under the heat preservation condition₂And (3) heating to 1900-2200 ℃ at the speed of 1-5 ℃/min under the condition of pressure preservation under the pressure preservation and heat preservation of 2-10 MPa, and naturally cooling to room temperature to obtain the in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic.

2. The method for preparing in-situ generated aluminum nitride-silicon carbide solid solution complex phase ceramic according to claim 1, wherein the binder is one or more of phenolic resin, epoxy resin, acrylic acid, silica sol and aluminum dihydrogen phosphate.

3. The method for preparing the in-situ generated aluminum nitride-silicon carbide solid solution complex phase ceramic according to claim 1, wherein the purity of the nitrogen is more than or equal to 98.5%.

4. An in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic is characterized in that the in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic is prepared by the preparation method of the in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic according to any one of claims 1 to 3.

Technical Field

The present invention belongs to the field of aluminium nitride-silicon carbide solid solution composite ceramic technology. In particular to an in-situ generated aluminum nitride-silicon carbide solid solution complex phase ceramic and a preparation method thereof.

Background

The AlN material has the good performances of high thermal conductivity, good electrical insulation, high strength, high hardness, corrosion resistance, wear resistance and low thermal expansion coefficient, and is widely applied to the fields of semiconductor materials, microwave electron attenuation materials, refractory materials and the like. The SiC has small coefficient of thermal expansion, high hardness, high mechanical strength, chemical corrosion resistance, excellent wear resistance and stable chemical performance, and is widely applied to many fields of high-temperature ceramics, aerospace and the like. Although aluminum nitride and silicon carbide are excellent ceramic materials, they have inherent disadvantages and limitations, which limit their development and application to some extent. At present, the preparation of composite materials is an effective way for improving the material performance, and AlN and alpha-SiC have similarities in atomic size, molecular weight, crystal structure, density and high-temperature performance, so that a solid solution can be formed in a larger chemical composition region, and a rare strong covalent bond in non-oxide ceramics is formed between the AlN and the alpha-SiC, so that the possibility of compounding the AlN and the alpha-SiC is further increased, the inherent defects of the AlN and the alpha-SiC are expected to be improved, and the material performance is improved.

In order to obtain high-performance AlN/SiC solid solution multiphase ceramics, scholars at home and abroad adopt different technical routes and methods, such as Wei et al (Wei W C J, Lee R. pressure sintering of AlN-SiC composites [ J ]]Journal of materials Science,1991,26(11):2930-₂O₃Ratio of CaO to Al₂O₃The densification of the sintered body can be better promoted, and α -SiC has a similar structure with AlN and a very small difference of lattice constant, so that α -SiC can be better combined with AlN compactly and form a solid solution than β -SiC, and XRD and NMR researches of Tan Showa and the like (Tan Showa, Yueyao, SiC-AlN solid solution [ J]The silicate science 1997 (3):345-349) also adopts a pressureless sintering method, uses 6H-SiC as raw material to mix a small amount of A1N, and is in Ar atmospherePressureless sintering at 2050 ℃ to prepare the single-phase 4H-type SiC-AlN solid solution. Ruh et al (Ruh R, ZangvilA. composition and properties of hot-pressed SiC-AIN solids [ J)]Journnalof the American Ceramic Society,2010,65(5): 260-.

The AlN/SiC solid solution complex phase ceramic prepared by the method is usually prepared by mechanically mixing a plurality of raw materials and then sintering at a high temperature, the dispersibility and uniformity of the internal phase of the complex phase ceramic are difficult to control, so that the performance of the material is difficult to regulate and control, and meanwhile, the AlN is hydrolyzed due to long-time ball milling, so that the chemical components of the material are changed, and the performance of the material is reduced.

In addition, "an AlN-SiC solid solution whisker and a preparation method thereof" (CN 201710875873.0) also adopt a single ternary carbide Al₄SiC₄Although AlN/SiC solid solution whiskers were produced as a starting material, the patent technique does not describe whether or not whiskers were formed only on the surface of a bulk dense sample and the inside of the sample was completely reacted to form an AlN/SiC solid solution.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic, which has simple process and convenient operation, and the in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic prepared by the method has low density, light weight, uniform and compact structure, high temperature resistance, oxidation resistance, hydration resistance and excellent mechanical property.

In order to achieve the purpose, the invention adopts the technical scheme that:

step one, according to Al₄SiC₄The mass ratio of the powder to the binder is 100: 2-5, and the Al is added₄SiC₄And mixing the powder and the binder to obtain a mixture.

The Al is₄SiC₄The purity of the powder is more than or equal to 98.0 wt%, and Al₄SiC₄The particle size of the powder is less than or equal to 150 mu m.

And secondly, pre-pressing and molding the mixture under the condition of 5-50 MP, then carrying out isostatic pressing under the condition of 100-300 MPa, then placing the mixture in a constant-temperature drying box, and drying the mixture for 1-5 hours at the temperature of 110 ℃ to obtain a prefabricated blank body.

Step three, the prefabricated blank body is placed into a graphite crucible, then the graphite crucible is placed into a hot pressing furnace, the graphite crucible is heated to 1100-1200 ℃ from room temperature at the speed of 5-10 ℃/min under the condition that the pressure is less than or equal to 0.1mbar, and N is filled under the heat preservation condition₂And (3) heating to 1900-2200 ℃ at the speed of 1-5 ℃/min under the condition of pressure preservation under the pressure preservation and heat preservation of 2-10 MPa, and naturally cooling to room temperature to obtain the in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic.

The binder is more than one of phenolic resin, epoxy resin, acrylic acid, silica sol and aluminum dihydrogen phosphate.

The purity of the nitrogen is more than or equal to 98.5 percent.

By adopting the scheme, compared with the prior art, the invention has the following advantages:

the invention adopts ternary carbide Al₄SiC₄The powder is a single raw material, a certain amount of binder is added, and the in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic is obtained under the air pressure sintering process, and the process is simple and convenient to operate.

Al used in the invention₄SiC₄The powder has excellent oxidation resistance and hydration resistance, and can obviously improve the oxidation resistance and the hydration resistance of the aluminum nitride-silicon carbide solid solution complex phase ceramic generated in situ.

According to the invention, the prefabricated blank body can generate nitridation reaction to generate AlN and SiC along with the increase of the sintering temperature, the AlN and the SiC can be uniformly distributed in a product without a mechanical mixture phase, and the AlN and the SiC can generate solid solution along with the further increase of the temperature to 1900-2100 ℃, and the solid solution can be generated between the AlN and the SiC due to different evaporation and diffusion mass transfer rates of all phases in the material, and the phases are tightly combined without obvious interfaces, so that the prepared in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic has the advantages of uniform and compact structure, high temperature resistance and three-point bending strength of 120-195 MPa.

The invention adopts a gas pressure sintering method, so that the Al can be more compact₄SiC₄The blank body is fully nitrided, and the prepared in-situ generated aluminum nitride-silicon carbide solid solution multiphase ceramic has light weight and the density of 2.21-2.406 kg/m³。

Therefore, the method has simple process and convenient operation, and the prepared in-situ generated aluminum nitride-silicon carbide solid solution composite ceramic has low density, light weight, uniform and compact structure, high temperature resistance, oxidation resistance, hydration resistance and high strength.

Detailed Description

The binder used in the preparation method provided by the invention is not limited, and can be used as long as the binder can be uniformly mixed with a powder material and can be prepared into a block sample. The invention will be further described and illustrated with reference to specific embodiments thereof, it being understood that the following specific examples are intended to illustrate the invention and are not to be construed as limiting the scope thereof.

In this embodiment:

the Al is₄SiC₄The purity of the powder is more than or equal to 98.0 wt%, and the granularity is less than or equal to 150 mu m;

the purity of the nitrogen is more than or equal to 98.5 percent;

the binder is more than one of phenolic resin, epoxy resin, acrylic acid, silica sol and aluminum dihydrogen phosphate.