论文总字数：33209字

摘 要

基于聚碳硅烷先驱体转化法的碳化硅（SiC）纤维抗高温氧化，、耐化学腐蚀、低密度、高强度等优异性能，在高科技高精尖领域具有十分广阔的应用前景；添加钛、铝、锆等元素的改性聚碳硅烷是进一步提高SiC纤维耐热性能的有效途径。其中，含锆SiC纤维由于其电阻率连续可调，是潜在的吸波结构材料，因此，研究不同处理条件下的含锆SiC纤维电阻率的规律，并分析不同因素对其电阻率的影响具有及其重要的意义。

本论文以正丁醇锆为锆源合成含锆聚碳硅烷先驱体，用自制单孔纺丝装置，制备出含锆SiC纤维。论文以含锆SiC纤维室温电学性能主要以纤维电阻率为主要研究方向，通过寻找合适的纤维测量电极，对不同锆含量（1%Zr、10%Zr）、不同温度（1000℃、1200℃、1300℃、1400℃），不同气氛（纯Ar、纯H₂、30%H₂,70%Ar混合气氛）下含锆SiC纤维的电阻率进行测量，定性对比分析PCS-Zr纤维的电阻率的规律与各因素对其影响。研究主要结论如下：

（1）通过对石墨粉、铜粉与环氧树脂固化形成电极，导电胶、石墨片电极，电烙铁焊锡电极和银浆电极四种电极的测量效果对比，选择用银浆将10根一束的纤维粘结在铜片基底之上，夹持两端铜片以测量电阻。

（2）随着温度的上升，含锆SiC纤维的电阻率降低。在纯氩气条件下烧成的纤维，当烧成温度上升，电阻率急剧下降；在纯氢气和混合气体条件下烧成的纤维，电阻率随温度的变化下降不明显。

（3）不同气氛条件下烧成的含锆SiC纤维的电阻率不同。在氢气氛条件下烧成的含锆SiC纤维的电阻率比在同温度氩气下烧成含锆SiC纤维的电阻率大。

（4）含锆SiC纤维的锆含量对电阻率的影响不显著。

（5）通过SEM对含锆SiC纤维的形貌和能谱进行分析表明：本论文所使用含锆SiC纤维的表面光滑平坦，没有明显的缺陷如孔洞、裂纹、沟槽等表面缺陷。在纯氩气氛中热解烧成，随着烧成温度的升高，纤维中碳含量所占比重从22.08增加到33.18，且n(C)/n(Si)从0.70增大到1.31，纤维电阻率急剧减小。随着锆含量的增加，纤维中碳所占比重上升，硅所占比重下降，1000℃下烧成n(C)/n(Si)由0.70增大到1.28，1200℃烧成n(C)/n(Si)由1.08增大到1.38，而电阻率无明显变化。

关键词：含锆SiC纤维；电极制备；电阻率；

Abstract

Silicon Carbide (SiC) fibers produced via polymer pyrolysis are one the most promising reinforcement materials in the field of high-technology because of their high tensile strength, high elastic modulus, and good thermal stability. It is well known that addition of elements such as titanium, aluminum and zirconium into the PCS, prior to subsequent cross-linking polymerization and pyrolysis, can significantly improve the heat resistance properties of SiC fibers. The SiC fiber which adds zirconium is the potential absorbing structure material because of its continuous adjustable resistivity. Thus, It’s important for studying the rule of zirconium- containing SiC fiber resistivity under different processing conditions and analyzing the influence of different factors on the resistivity.

In this thesis, synthesis of zirconium-modified polycarbosilane was carried out by using polycaybosilane and zirconium n-butoxiden-butyl alcohol as starting materials under argon flow and heating. This paper’s main research direction is the resistivity at room temperature of zirconium- containing SiC fiber Firstly, find the appropriate fiber measuring electrode. Then, measure  the resistivity of different content of zirconium (Zr 1%, 10%), different temperatures (1000℃, 1200℃, 1300℃, 1200 ℃), different atmosphere ( pure Ar, pure H₂, 30% H₂, 70%Ar mixed atmosphere) to analysis rules of PCS-Zr fibers resistivity and the influence of different factors on the resistivity. The main results are summarized as follows.

(1) Based on the four electrode measurement result of graphite powder, copper powder and epoxy resin curing electrode, conductive adhesive, graphite electrode, soldering iron solder electrode and silver paste electrode, we choose the silver paste to measure resistivity,. Silver paste was put on the fiber bundle to bond the fibers on the copper substrate and then the resistivity between the two silver electrodes was measured.

(2) As temperatures rising, the resistivity of zirconium- containing SiC fiber decreasing. Under the condition of pure argon gas atmosphere, when the temperature rising, the resistivity fell sharply; under the condition of pure hydrogen gas atmosphere and mixed gas atmosphere, the resistivity changes with temperature is not obvious.

(3) Under the condition of different atmosphere, the resistivity of zirconium-containing SiC fiber is different. The resistivity under hydrogen atmosphere is higher than that under argon atmosphere at the same temperature

(4) The influence of the content of zirconium in the fiber on the resistivity was not significant.

(5) SEM on the zirconium- containing fiber morphology and energy spectrum analysis showed that: the fiber’s surface is smooth and flat and there are no obvious surface defects such as holes, cracks, and so on. With the increase of pyrolysis temperature, the carbon content in the fiber increased from 22.08 to 33.18, and n (C)/n (Si) increased from 0.70 to 1.31, and the fiber’s resistivity decreases sharply when fiber was under the pure argon atmosphere. With the increase of zirconium content, carbon percentage increased and silicon percentage declined in the fiber. The fiber’s n (C)/n (Si) increased from 0.70 to 1.28 when pyrolysising at 1000℃, and the fiber’s n (C)/n (Si) increased from 1.08 to 1.38 when pyrolysising at 1200℃.At the same time, no significant change of resistivity was observed.

Keywords: Zirconium-containing silicon carbide fibers; electrode paste; resistivity.

目 录

摘要 I

Abstract II

第一章 绪 论 1

1.1含锆碳化硅（SiC）纤维的电性能研究背景 1

1.2 材料对电磁波屏蔽和吸收的机制 2

1.3 SiC纤维的制备方法 3

1.4 掺杂异质元素的SiC纤维的制备方法 4

1.4.1 含Ti的SiC陶瓷先驱体 5

1.4.2 含Zr的SiC陶瓷先驱体 5

1.4.3 含Al的SiC陶瓷先驱体 6

1.4.4 含B、N的SiC陶瓷先驱体 6

1.5 碳化硅（SiC）纤维的电性能研究现状 6

1.6论文研究目的及研究内容 8

第二章 实验与表征 10

2.1 论文研究方案总体设计 10

2.2 实验原料与分析测试仪器 11

2.2.1 原料与试剂 11

2.2.2实验仪器 11

2.3 含锆SiC纤维的合成 12

2.4 测试与表征 13

2.4.2 纤维的直径测量 16

2.4.3 纤维表面形貌观察 17

2.4.4 纤维表面成分分析 17

2.5 本章小结 17

第三章 含锆SiC纤维的室温电性能、成分及相组成分析 18

3.1 不同处理条件下含锆SiC纤维的电阻率 18

3.2 烧成温度对含锆SiC电阻率的影响 19

3.3 气氛对含锆SiC纤维电阻率的影响 20

3.4 锆含量对含锆SiC纤维电阻率的影响 23

3.5 含锆SiC纤维的形貌和能谱分析 23

3.6 本章小结 29

第四章 结论 31

参考文献 33

致谢 36

第一章 绪 论

1.1含锆碳化硅（SiC）纤维的电性能研究背景

随着我国科技的不断进步，航空航天、能源、交通、军事装备等领域对具有优异耐高温性、抗氧化性、高强度高模量、具有吸波特性的材料的需求越来越急迫^[1-3]。陶瓷基复合材料作为一种新型的结构材料日益受到人们的重视。而先驱体转化法制备的的SiC纤维因高热稳定性，高抗拉强度和高弹性模量，常被作为复合材料的增强体^[4]。

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