CN-122010574-A - Complex-phase ceramic material with high density and excellent electromagnetic shielding performance and low-temperature sintering preparation method thereof

Abstract

The invention discloses a complex phase ceramic material with high density and excellent electromagnetic shielding performance and a low-temperature sintering preparation method thereof. According to the method, ultra-high temperature ceramic powder and oxide powder are mixed in proportion, uniform powder is obtained through wet ball milling and rotary evaporation drying, and then a hot press sintering or spark plasma sintering process is adopted, and the temperature is kept for 5-60 minutes under the conditions of 800-1500 ℃ and 10-200 MPa, so that low-temperature densification of the ceramic is realized. The relative density of the obtained complex phase ceramic is more than or equal to 95 percent, and the average electromagnetic shielding efficiency in the X wave band is more than or equal to 30 dB. The invention greatly reduces the sintering temperature of the ultra-high temperature ceramic, maintains high density and excellent electromagnetic shielding performance, reduces energy consumption and cost, and is suitable for electromagnetic shielding, high-temperature thermal protection and light structure-function integrated composite material components.

Inventors

• ZOU JI
• YANG QIAN
• LIU JINGJING
• WANG WEIMIN
• FU ZHENGYI

Assignees

• 武汉理工大学

Dates

Publication Date

20260512

Application Date

20260206

Claims (10)

1. 1. A method for preparing complex phase ceramics with high density and excellent electromagnetic shielding performance by low temperature sintering, which is characterized by comprising the following steps: (1) Mixing the ultra-high temperature ceramic powder with the oxide powder according to a preset proportion to obtain mixed powder; (2) And placing the mixed powder into a die, and sintering by adopting a pressure sintering process, wherein the target sintering temperature is 800-1500 ℃, simultaneously applying 10-200 MPa of preset pressure, and preserving heat for 5-60 min at the target sintering temperature to obtain the densified complex phase ceramic material.
2. 2. The method of claim 1, wherein the ultra-high temperature ceramic comprises at least one of boride MB 2 , carbide MC, nitride MN, wherein M is one or more of Zr, hf, nb, ta.
3. 3. The method of claim 1 or 2, wherein the oxide comprises one or more of MgO and SiO 2 、Al 2 O 3 .
4. 4. The method of claim 1, wherein the volume fraction of the ultra-high temperature ceramic powder in the mixed powder is 20-100%, and the volume fraction of the oxide powder in the mixed powder is 0-80%.
5. 5. The method of claim 1, wherein in the step (1), the mixing is performed by wet ball milling for 6-20 hours, the ball milling medium comprises ZrO 2 grinding balls and absolute ethyl alcohol, the slurry is subjected to rotary evaporation drying after mixing, and then crushed and sieved to obtain the mixed powder.
6. 6. The method according to claim 1, wherein in the step (2), the pressure sintering process is hot press sintering or spark plasma sintering.
7. 7. The method of claim 6, wherein the temperature is increased from room temperature to 400 ℃ at a first rate and then to the target sintering temperature at a rate of 20-100 ℃ per minute when spark plasma sintering is employed, and wherein the pressure is gradually increased from the initial contact pressure to a preset pressure and maintained when the temperature reaches 600 ℃.
8. 8. The method of claim 6, wherein when hot press sintering is employed, the temperature is raised from room temperature to a target sintering temperature at a rate of 5-30 ℃ per minute, and wherein when the temperature reaches 600 ℃, the pressure is gradually raised from the initial contact pressure to a preset pressure and maintained.
9. 9. A complex phase ceramic material with high density and excellent electromagnetic shielding performance is characterized in that the complex phase ceramic material is prepared by the method of any one of claims 1-8, the relative density of the complex phase ceramic material is more than or equal to 95%, and the average shielding effectiveness in an X frequency band is more than or equal to 30dB.
10. 10. Use of the composite ceramic material of claim 9 in electromagnetic shielding, high temperature thermal protection or lightweight structural-functional integrated composite components.

Description

Complex-phase ceramic material with high density and excellent electromagnetic shielding performance and low-temperature sintering preparation method thereof Technical Field The invention relates to the technical field of electromagnetic shielding and protecting materials, in particular to a complex phase ceramic material with high density and excellent electromagnetic shielding performance and a low-temperature sintering preparation method thereof. Background With the rapid development of electronic information technology, the problems of electromagnetic pollution and electromagnetic interference are increasingly serious, and the development of high-performance electromagnetic shielding materials becomes a research hotspot. Among them, ceramic matrix composite materials, particularly ultra-high temperature ceramics represented by transition metal borides (such as TiB 2,ZrB2,HfB2) and carbides (such as HfC, tiC), are considered as a very potential new generation of high temperature, corrosion resistant electromagnetic shielding materials due to their high melting point, high hardness, good chemical stability, and excellent electromagnetic wave absorption and shielding performance in the mid-high frequency band. However, such materials face a key technical bottleneck in practical applications, namely extremely high sintering densification temperatures. Boride and carbide are strong in covalent bonding and low in self-diffusion coefficient, and usually require high temperatures above 2000 ℃ (e.g. 2100 ℃) and/or application of external pressure (e.g. hot pressing, spark plasma sintering) to achieve densification. Such high sintering temperatures cause serious problems. Firstly, the ultra-high sintering temperature means huge energy consumption and high production cost, which limits the mass production and application of the carbon fiber reinforced ceramic matrix composite, and secondly, limits the research of the carbon fiber reinforced ceramic matrix composite. Carbon fibers undergo severe graphitization, grain growth and mechanical property degradation at temperatures exceeding 1500 ℃, even ablating in an oxidizing atmosphere. Therefore, the combination of boride/carbide ceramics and light-weight high-strength carbon fiber composite materials is difficult to realize through the traditional ultra-high temperature sintering process, and an integrated component with excellent electromagnetic shielding performance and light-weight structural bearing characteristic cannot be prepared. To overcome the above-mentioned sintering problems, the research community has attempted to introduce various sintering aids to improve its sintering kinetics. Common additives include ① carbides (such as SiC, B 4 C) which promote substance migration by forming a liquid or solid solution, ② layered compounds (such as hexagonal boron nitride hBN) which may aid densification by interfacial slip or providing diffusion channels, ③ silicides (such as MoSi 2) and certain transition metal carbides (such as WC, VC) which not only can effectively reduce sintering temperatures, promote densification processes, but also can often refine grains, optimize microstructure, and further promote the overall thermophysical and mechanical properties of the material. In recent years, another class of refractory metal oxides (e.g., al 2O3,Y2O3,ZrO2, etc.), which possess high melting points, excellent thermal stability and chemical inertness, and a mature application background in extreme environments (e.g., aerospace thermal protection systems), have also been explored for incorporation as potential secondary phases or sintering aids into ultra-high temperature ceramic systems in an effort to improve manufacturability while potentially introducing new regulatory dimensions for electrical or interfacial properties. In summary, the core contradiction between the intrinsic properties of the materials (excellent electromagnetic shielding potential) and the demanding manufacturing conditions (ultra-high temperature sintering) required to achieve this property is the current state of the art development. Therefore, development of a boride/carbide/nitride preparation method can remarkably reduce the densification sintering temperature of the ultra-high temperature ceramic (for example, from a medium temperature range of >2000 ℃ to 1200 ℃ or below) without sacrificing the final performance (high density, uniform microstructure and excellent electromagnetic shielding performance) of the material, and has great scientific and engineering significance. The method can greatly reduce energy consumption and cost, broaden application range of the method in high technical fields (such as aerospace, high-end electronic communication, precision instrument protection and the like), and more importantly, pave roads for successfully realizing effective compounding of the method and a carbon fiber reinforcement, so that new chapters for designing and manufacturing the next-ge