论文总字数：18907字

摘 要

微波衰减材料是一种用于吸收特定频段电磁波的吸波材料，主要应用于雷达、预警机、战斗机等军用设备的真空电子器件中。微波衰减材料不仅要求具备优异的吸波性能，还需具备出色的导热能力以及时将热量传导出去。此外，由于电真空器件的应用环境主要是高真空、高功率、高频率等极端条件，因此，微波衰减材料需要具备高的致密性和一定的力学性能来满足实际中应用的性能要求。

本文从微波衰减材料的应用出发，以AlN为基体，通过添加不同含量的球形碳衰减剂SG和第三相半导体SiC，研究了氮化铝基微波衰减材料的相组成和烧结性能、力学性能、导热性能、衰减性能以及介电性能的变化。

在AlN-SG体系中，随着球形石墨（SG）含量的增加（0~8wt%），复相材料的反射损耗增幅明显，表现出了明显增强的微波吸收性能。在8.2~12.3GHz频段，当SG含量为7wt%时，复合材料的RL值最小为-14.2dB，此时微波吸收能力最好。

在AlN-SG-SiC体系中，随着碳化硅（α-SiC）含量的增加（0~50wt%），复合材料的抗弯强度和介电常数呈现出逐渐增大的趋势，相对密度先增大后减小，SiC含量为10wt%时， AlN-SG-SiC复相材料的烧结性能最好，相对密度为99.2%。热导率随SiC的增加先减小后增大，SiC含量为30wt%时，导热性能相对最好，热导率为47.6 W/(m·K)。在8.2~12.3GHz频段，只有当SiC含量为5wt%、10wt%和15wt%时，复合材料的反射损耗较小，RL值分别达到-19.8dB、-18.5dB和-18.6dB，SiC含量超过15wt%时，微波吸收能力减弱。

关键词：微波衰减材料 AlN 球形碳 热压烧结

Preparation and Properties of AlN / Spherical Carbon Multiphase Microwave Attenuation Materials by Hot Press Sintering

Abstract

Microwave attenuating material is a kind of absorbing material used to absorb electromagnetic waves in a specific frequency band. It is mainly used in vacuum electronic devices such as radar, early warning aircraft, fighter aircraft and other military equipment. Microwave attenuating materials require not only excellent wave absorption properties, but also excellent thermal conductivity to conduct heat in a timely manner. In addition, because the application environment of electric vacuum devices is mainly high vacuum, high power, high frequency and other extreme conditions, therefore, microwave attenuation materials need to have high density and certain mechanical properties to meet the performance requirements of practical applications.

In this paper, starting from the application of microwave attenuating materials, using AlN as a matrix, by adding different amounts of spherical carbon attenuating agent SG and third-phase semiconductor SiC, the phase composition and sintering properties, mechanical properties, and mechanical properties of aluminum nitride-based microwave attenuating materials were studied. Changes in thermal conductivity, attenuation, and dielectric properties.

As the content of spherical graphite increases, the reflection loss of the complex phase material increases significantly, showing significantly enhanced microwave absorption performance. In the composite material with spherical graphite content of 7wt%, the minimum RL value is -14.2dB.

As the content of silicon carbide (α-SiC) increases, the flexural strength and dielectric constant show a gradually increasing trend. When the SiC content is 10wt%, the AlN-SG-SiC composite material has the best sintering performance, with a relative density of 99.2%. When the SiC content is 30wt%, the thermal conductivity is relatively best, and the thermal conductivity is 47.6 W/(m·K). When the SiC content is 5wt%, 10wt% and 15wt%, the reflection loss of the composite material is small, and the RL value reaches -19.8dB, -18.5dB and -18.6dB respectively. When the SiC content exceeds 15wt%, the microwave absorption capacity is weakened.

Key Words: Microwave attenuating material; AlN; Spherical carbon; Hot pressed sintering

目录

摘 要 Ⅰ

Abstract Ⅱ

第一章 绪论 1

1.1 引言 1

1.2 微波衰减材料的介绍及分类 1

1.2.1 微波衰减材料的介绍 1

1.2.2 微波衰减材料的分类 2

1.3 AlN基复相衰减陶瓷的简介 2

1.4 AlN基复相衰减陶瓷的种类 2

1.4.1 AlN/C复相衰减陶瓷 3

1.4.2 AlN/金属复相衰减陶瓷 3

1.4.3 AlN/半导体复相衰减陶瓷 4

1.4.4 AlN/TiC复相衰减陶瓷 4

1.5 AlN基复相衰减陶瓷的烧结方法 4

1.5.1 无压烧结 5

1.5.1 热压烧结 5

1.5.3热等静压烧结 HIP 5

1.5.4 微波烧结 6

1.6 烧结助剂对AlN基复相衰减陶瓷性能的影响 6

1.6.1氧化物烧结助剂 6

1.6.2非氧化物烧结助剂 6

1.6.3复合烧结助剂 7

1.7 本课题的研究目的和内容 7

第二章 实验 8

2.1实验原料 8

2.2实验仪器及设备 8

2.3 实验过程 8

2.3.1 AlN-SG的制备 8

2.3.2 AlN-SG-SiC的制备 9

2.4材料的表征与测试 9

2.4.1 物相组成分析 9

2.4.2 烧结性能测试 9

2.4.3 导热性能测试 10

2.4.4 介电性能测试 10

2.4.5 力学性能测试 10

2.4.6 微波衰减性能计算 10

第三章 结果与讨论 11

3.1 AlN-SG复合材料的介电性能及微波衰减性能 11

3.1.1 介电性能 11

3.1.2 微波衰减性能 12

3.2 AlN-SG-SiC复合材料的结构和性能 13

3.2.1 物相分析 13

3.2.2 烧结性能 14

3.2.3力学性能 14

3.2.4导热性能 15

3.2.5介电性能 15

3.2.6微波衰减性能 16

第四章 结论 17

参考文献 18

致谢 20

第一章 绪论

1. 1引言

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