石英纤维/SiO_(2)复合材料透波罩吸水增重对电性能的影响

Influence of moisture gain on electrical properties of quartz fiber/SiO_(2) composite radome

受制备工艺的影响,石英纤维/SiO_(2)复合材料透波罩具有较高的比表面积,因此在空气中易吸收水分。本文通过研究吸水对石英纤维/SiO_(2)复合材料试片及透波罩整罩电性能的影响,给出透波率下降与吸水增重的规律;通过对透波罩整罩吸水过程的研究,给出了吸附动力学模型。结果表明:吸水后材料的介电常数变化较小,但损耗角正切呈倍数增加;在20℃~30℃、65%~75%相对湿度环境条件下,透波罩未采取防潮措施时,在2周内达到吸附平衡,平衡吸附量为0.083 kg/m^(2),最大吸水率为6.3‰,16 GHz下透波率下降7%~11%,之后基本保持不变。透波罩整罩吸水过程符合Langergren赝二级吸附动力学模型。基于这些特点,石英纤维/SiO_(2)复合材料透波罩在使用时必须采取一定的防潮措施,以降低材料对空气中水分的吸附能力,保持透波性能稳定。

In order to understand the influence of moisture gain on the electrical properties of quartz fiber composite radome, both simulation and experiments are performed on the radome and test samples. In this paper, electrical properties of quartz fiber composite before and after moisture gain are measured using both test samples and a radome. The wave transmissivity of the radome as a function of moisture gain are presented. And, the moisture absorption model of the radome is also proposed. The results show that quartz fiber composites usually have relatively high porosity and specific surface area, and tend to absorb moisture in the air. The moisture gain influences the electrical properties of quartz composite radome. The dielectric constant is slightly affected by the moisture gain, but the loss angle tangent increases by c.a. 3 times. The unmiostureproofed radome reaches absorption equilibrium within 2 weeks at the temperature of 20 ℃~30 ℃ and humidity of 65%~75%, the equilibrium and maximum absorption is 0.083 kg/m^(2) and 6.3‰, respectively. The wave transmissivity of the radome drops by 7%~11% during the absorption, and keeps constant thereafter. The moisture absorption process basically agrees with the Langergren pseudo-second-order kinetic model. In summary, moisture gain has innegligible influence on the electrical properties and wave transmissivity of the radome. And, proper moistureproof measures must be taken to protect the quartz fiber composite radome from gaining moisture in the air.