导　　师： 张玉军

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 山东大学

摘　　要： 本文以Si/_3N/_4基陶瓷复合材料在导弹天线罩上的应用为基础,针对Si/_3N/_4、BN、AlN等优良的介电性能及机械性能进行材料设计,研制能满足宽频高马赫数导弹使用要求的天线罩候选材料,推动国内高速导弹发展。 本文研究了氮化硅陶瓷的气氛压力烧结工艺,分析了烧结温度、气氛等因素对氮化硅烧结过程的影响。 本文详细介绍了Si-B-N-O材料体系和Si-B-N-O-Al材料体系的成分设计,研究了各材料组分含量对材料气孔率、机械性能、介电性能等的影响。 研究结果表明:Y/_2O/_3的加入能有效促进材料的烧结,其最佳加入量为5/%;BN粉料的加入可以有效降低Si/_3N/_4基陶瓷复合材料的介电常数,提高材料的抗热震性能,但对气氛压力烧结Si/_3N/_4有明显的阻滞作用,其最佳加入量为25～35/%/(质量分数/);适量纳米SiO/_2粉体的加入对于提高Si/_3N/_4基陶瓷复合材料的致密化和抗弯强度作用非常明显,其最佳加入量为5/%/(质量分数/);AlN的加入使Si-B-N-O体系在烧结过程中形成Sialon陶瓷相,从而起到明显的增强增韧效果,但当AlN的加入量过多时,由于AlN在烧结过程中的分解,会在材料内部形成气泡,反而会影响材料的机械性能;气孔率的增加能有效降低材料的介电常数和介电损耗,但对材料的机械性能产生不利影响。 本文借助扫描电子显微镜/(SEM/)、X-射线衍射仪/(XRD/)等技术手段对本课题所研究的两大材料体系的微观结构与相组成进行了分析研究。 X射线分析表明:烧结后Si-B-N-O体系材料的主晶相为β-Si/_3N/_4、BN和玻璃中间相Si/_2ON/_2;Si-B-N-O-Al材料体系的主晶相为Si/_5AlON/_6和BN,含有少量的SiO/_2和Al/_2O/_3。 扫描电镜分析表明:Si-B-N-O体系材料呈蜂窝状结构,气孔分布比较均匀,晶相中柱状的β-Si/_3N/_4和层片状的BN交叉层叠分布;Si-B- The fundamental goal of the present study is to develop a process of silicon nitride based ceramics for radome application. The composite materials for a broad brand high-speed missile radome have been studied based on the superior dielectric properties and mechanical performance of Si3N4 BN, A1N materials.The gas-pressure-sintering/(GPS/) technology of silicon nitride ceramics has been studied in this paper. The properties of GPS-Si3N4 ceramics with the temperature , atmosphere , etc. have been discussed.The system of Si-B-N-O compound and Si-B-N-O-Al compound have been designed in this paper. The properties of the porous content, the mechanical performance and the dielectric properties with any component varieties have been discussed.The experimental results show that: the addition of Y2O3 can promote the sintering of the matetial effectively, and its best addition amount is 5wt/%; the addition of the power material of BN can reduce the dielectric constant, and improve the thermal shock resistance of the materials effectively, but it will also block the GPS process, so its best addition amount should be 25~35wt/%; the addition of nanometer SiO2 power can improve the densification and the flexural strength of the materials obviously, and the best addition amount is 5wt/%; the addition of A1N will improve the flexural strength and fracture toughness of the materials greatly for the formation of Sialon ceramics. But if too much A1N is added, the mechanical performance of the materials will be reduced for the formation of big pores in the course of A1N decomposition; the dielectric constant and the dielectric loss deduce with the increasing of the porous content, and the mechanical performance deduces too.SEM, XRD, etc. has been applied to analyze the microstructure and crystalline phase composition of two systems.By XRD, it shows that the main crystalline phases of the Si-B-N-0 system are 3 -Si3N4> BN andSi2ON2, and the main crystalline phases of the Si-B-N-O-Al are Si5A10N6, BN and a few quantity of

关 键 词： 氮化硅 氮化硼 氮化铝 天线罩 气氛压力烧结

领　　域： [兵器科学与技术]