中文摘要：

连续氮化硅陶瓷纤维是透波/承载一体化陶瓷基复合材料的关键原材料,也是制约复合材料耐高温性能与力学性能的关键因素。系统研究了国防科技大学研制的连续氮化硅纤维的组成结构及其力学性能和介电性能,分析了纤维在氮气中高温处理后组成结构与单丝强度变化规律。结果表明,氮化硅纤维主要以Si_3N_4结构存在,组成上接近化学计量比,介电常数为68,介电损耗为0.01~0.08,室温单丝强度约1.5GPa,弹性模量140GPa,在1 350℃以下纤维强度保留率超过90%,在1 400和1 450℃氮气中处理1h仍保持了非晶结构,强度保留率分别为75%和30%,综合性能满足了高温透波复合材料的基本要求。

英文摘要：

Amorphous silicon nitride fibers were prepared by nitridation of polycarbosilane fiber,and their com-position,structure and properties were characterized using popular methods.KD-SN fiber was produced by Na-tional University of Defense Technology （NUDT）,given near chemical stoichiometric composition of Si3 N4 with traces oxygen and carbon.The volume density and linear density were 2.3 g/cm3 and 280 tex respectively. The dielectric constant was 6-8 and the tanδwas 0.01-0.08.The tensile strength and modulus of elasticity were 1.5 and 140 GPa respectively.The high temperature tests were taken in the nitrogen atmosphere at 1 300, 1 350,1 400 and 1450 ℃ with a holding time of 1 h.The tensile strength was kept above 90% of the original fi-ber.Over 1 350 ℃,the tensile strength and modulus decreased sharply,even though the composition changed little.The fibers could keep their amorphous state before 1 450 ℃ but nanopores’volume was increased signifi-cantly.Overall,the KD-SN silicon nitride fiber offers a promising choice for high temperature ceramic matrix composites.