Electromagnetic wave absorption and mechanical properties of silicon carbide fibers reinforced silicon nitride matrix composites
Electromagnetic wave absorption and mechanical properties of silicon carbide fibers reinforced silicon nitride matrix composites
复制标题
碳化硅纤维增强氮化硅基复合材料的电磁波吸收及力学性能
DOI：
10.1016/j.jeurceramsoc.2018.12.038
复制
发表时间：
2019-04-01
影响因子：
5.7
通讯作者：
Cheng, Laifei
中科院分区：
文献类型：
--
作者：
Mo, Ran;Yin, Xiaowei;Cheng, Laifei
陶瓷基复合材料很难将良好的电磁波（EMW）吸收性能（反射系数，X波段RC小于-7 dB）和良好的力学性能（弯曲强度大于300 MPa，断裂韧性大于10 M P.m(1/2)）结合起来。为了解决这一问题，通过化学气相渗透技术设计并制备了两种吸波SiC纤维增强Si3N4基复合材料（SiCf/Si3N4）。研究了电导率对电磁波吸收性能的影响以及纤维/基体粘合强度对机械性能的影响。 SiCf/Si3N4复合材料具有相对较低的电导率（其传导损耗约为总介电损耗的33%），具有良好的电磁波吸收性能，即10 GHz时的相对复介电常数约为9.2-j6.4，整个X波段的RC低于-7.2 dB。其较低的相对复介电常数使复合材料与空气之间的阻抗更好地匹配，其强大的极化弛豫损耗能力有助于其吸收更多的电磁波能量。此外，具有适当强的纤维/基体结合强度，复合材料可以更有效地将载荷从基体传递到纤维，从而获得更高的弯曲强度（380 MPa）和断裂韧性（12.9 MPa·m(1/2)）。
It is difficult for ceramic matrix composites to combine good electromagnetic wave (EMW) absorption properties (reflection coefficient, RC less than -7 dB in X band) and good mechanical properties (flexural strength more than 300 MPa and fracture toughness more than 10 M P.m(1/2)). To solve this problem, two kinds of wave-absorbing SiC fibers reinforced Si3N4 matrix composites (SiCf/Si3N4) were designed and fabricated via chemical vapor infiltration technique. Effects of conductivity on EM wave absorbing properties and fiber/matrix bonding strength on mechanical properties were studied. The SiCf/Si3N4 composite, having a relatively low conductivity (its conduction loss is about 33% of the total dielectric loss) has good EMW absorption properties, i.e. a relative complex permittivity of about 9.2-j6.4 at 10 GHz and an RC lower than -7.2 dB in the whole X band. Its low relative complex permittivity matches impedances between composites and air better, and its strong polarization relaxation loss ability help it to absorb more EM wave energy. Moreover, with a suitably strong fiber/matrix bonding strength, the composite can transfer load more effectively from matrix to fibers, resulting in a higher flexural strength (380 MPa) and fracture toughness (12.9 MPa square m(1/2)).