薄型单层结构雷达吸波涂料的制备

依据阻抗匹配原理制备了一种薄型单层结构雷达波吸波涂料。试验结果表明,由电磁损耗型吸波剂、磁损耗吸波剂和导电高聚物吸波剂制备的1 mm厚度单层结构吸波涂层在8～18 GHz范围内雷达波反射率≤-8 dB,具有厚度薄、吸波频带宽、面密度低、吸波性能强的特点。     

偶联剂A151对羰基铁粉/甲基乙烯基硅橡胶吸波复合材料性能的影响

用偶联剂A151对吸波填料羰基铁粉(CI)进行表面处理,研究偶联剂A151用量对CI/甲基乙烯基硅橡胶(MVQ)吸波复合材料性能的影响。结果表明:偶联剂A151改善了CI与MVQ的相容性,提高了复合材料的加工性能,但对硫化速度有一定影响;添加偶联剂A151的复合材料硬度和拉伸强度增大,偶联剂A151/CI用量比为2%的复合材料综合物理性能较好;复合材料的内部损耗主要为磁损耗,偶联剂A151对复合材料吸波性能的影响很小。     

环氧树脂/玻璃纤维/石墨烯复合材料的电磁吸波性能

为了制备具有一定电磁吸波性能的结构型吸波材料,采用喷涂法制备了负载石墨烯微粒的玻璃纤维预浸料,并通过热压罐成型工艺进行固化,制备了环氧树脂/玻璃纤维/石墨烯吸波复合材料。研究了石墨烯含量对吸波复合材料电磁性能、吸波性能和力学性能的影响。通过三点弯曲测试结果可知,随着石墨烯含量的增加,环氧树脂/玻璃纤维/石墨烯吸波复合材料的弯曲强度先增大后减小,弯曲弹性模量增大,但总体变化幅度较小。矢量网络分析仪测试结果表明,随着石墨烯含量的增加,环氧树脂/玻璃纤维/石墨烯复合材料的介电常数逐渐增大,磁导率几乎不变,介电损耗正切角值逐渐增大。分析反射损耗计算结果可知,环氧树脂/玻璃纤维/石墨烯吸波复合材料的吸波性能主要由复合材料的厚度和石墨烯含量决定,随着复合材料厚度的增大,反射损耗峰值逐渐朝低频移动;随着石墨烯含量的增加,复合材料的吸波性能逐渐增大。当石墨烯质量分数为2.5%、复合材料厚度为1.7 mm时,环氧树脂/玻璃纤维/石墨烯复合材料具有最佳的吸波效果,此时反射损耗峰值为-11.8 dB,有效带宽为1.45 GHz。     

吸波填料W型六角晶系锶铁氧体对甲基乙烯基硅橡胶吸波性能的影响

研究3种W型六角晶系锶铁氧体(BMA-PX,WPS,WPX)作吸波填料对甲基乙烯基硅橡胶(MVQ)吸波性能的影响。结果表明:3种W型六角晶系锶铁氧体均为无规的碎石状颗粒,元素组成不同,吸波性能差异较大。铁元素质量分数较大的BMA-PX吸波MVQ磁损耗较大,容易实现阻抗匹配,在中高频下的电磁波反射率低,吸波性能优异。     

轻薄可控聚苯胺/还原氧化石墨烯复合材料吸波性能研究北大核心

利用原位聚合法合成聚苯胺/还原氧化石墨烯(PANI/rGO)复合材料。通过控制rGO的含量来调控电磁参数,改变吸波性能,为复合材料在不同吸波条件的应用提供了解决思路。使用扫描电镜、X射线粉末衍射分析仪、傅里叶变换红外光谱仪和矢量网络分析仪对复合材料进行表征和性能测试。当PANI/rGO复合材料含量为14%、吸波体厚度为2 mm时,在13.36 GHz最大反射损耗为-39.92 dB。反射损耗(RL)低于-10 dB的频段范围为11.44~15.53 GHz。     

纤维增强树脂基吸波复合材料的研究进展

简述了吸波材料的电磁屏蔽机制、吸波剂的分类和损耗机制以及微波波段的划分与应用,并从材料的选择、结构的设计以及获得的吸波效果等方面对目前纤维增强树脂基吸波复合材料的研究进行了对比总结,重点阐述了单层结构、多层结构、多层夹心结构以及频率选择表面的主要特点和研究现状。最后提出了纤维增强树脂基吸波复合材料目前存在的问题,并对今后的发展进行了展望。     

轻薄可控聚苯胺/还原氧化石墨烯复合材料吸波性能研究

利用原位聚合法合成聚苯胺/还原氧化石墨烯(PANI/rGO)复合材料。通过控制rGO的含量来调控电磁参数,改变吸波性能,为复合材料在不同吸波条件的应用提供了解决思路。使用扫描电镜、X射线粉末衍射分析仪、傅里叶变换红外光谱仪和矢量网络分析仪对复合材料进行表征和性能测试。当PANI/rGO复合材料含量为14%、吸波体厚度为2 mm时,在13.36 GHz最大反射损耗为-39.92 dB。反射损耗(RL)低于-10 dB的频段范围为11.44～15.53 GHz。     

结构型吸波复合材料的研究进展

结构型吸波复合材料具有吸波性能好、质量轻、可承载等优点,已成为当代吸波材料的主要发展方向,对隐身材料的设计和制造有着重要意义。本文从纤维增强体的截面形状和制备工艺、纤维的铺排结构和夹层复合结构、吸波剂改性等影响吸波复合材料吸波性能的主要因素出发,系统地总结了结构型吸波复合材料的最新研究热点和成果,并指出吸波复合材料的未来发展方向。     

介孔MFe_2O_4/rGO型宽频吸波剂的开发及应用

氧化石墨烯具有高比表面积和极佳的电性能,作为基体材料与磁损耗功能材料铁氧化物复合可达到优异的吸波性能。从制备方式的角度出发,总结了近年来几种主流的MFe_2O_4/rGO复合材料制备方法和研究进展,并对介孔MFe_2O_4/rGO型宽频吸波剂的发展趋势进行展望。     

纤维复合材料吸波性能研究

本文对纤维复合材料的吸波性能进行了研究。作者选择了五种纤维制成试样,测试了吸波率,并从纤维的微观和亚微观结构对吸波率大小进行了定性分析,提出具有较好吸波性能的纤维具有的结构特点。     

Microwave absorbing properties of carbon black/silicone rubber blend

In the frequency range of 2–18 GHz, the microwave absorbing properties of a carbon black/silicone rubber blend were investigated by changing the carbon black content and the thickness. The real part (ε′) and the imaginary part (ε″) of permittivity of the blends were calculated from the S‐parameters measured by a network analyzer. The reflection loss was simulated by using ε′ and ε″. The reflection loss less than ?10 dB could be obtained in the frequency range of 9.6ε13.5 GHz from the sample with 10 wt% of carbon black at 1.9 mm of thickness.     

Development of Low Density,Heat Resistant and Broadband Microwave Absorbing Materials (MAMs) for Stealth Applications

The development of low density and broadband microwave absorbers are the need of the hour to cater for the needs of all military platforms for stealth technology. The low density and broadband properties can be inculcated in microwave absorbers using dielectric lossy materials (e.g. carbon fibres, carbon nanotubes, carbon black, fullerene, graphite, graphene and silicon carbide fibre). Therefore, we designed low density and heat resistant microwave absorbing materials (MAMs) using a novel approach of ceramic fibre board manufacturing technology. The microwave absorbing composites were prepared with varying percentage of milled carbon fibres, discontinuous aluminosilicate fibres and silicone resin as the matrix. The physico-mechanical properties of microwave absorbing composites were determined. Reflection loss of microwave absorbing composites was measured in the frequency range 2–18 GHz by unique single horn interferometry technique. The electromagnetic properties were measured in X-band using free space measurement system. Based on these properties the effect of thickness on the microwave absorbing properties in X-band was simulated The effect of weight % variation of milled carbon fibres on the microwave absorbing properties of composites have been studied in the frequency range 2–18 GHz.     

4种网格结构模具用硅橡胶性能研究

分析了网格结构模具用4种不同的室温硫化硅橡胶的性能结果表明,该4种硅橡胶均具有较小的线收缩率及较长的凝胶时间,但加成型室温硫化硅橡胶较缩合型硅橡胶具有突出的室温力学性能、热稳定性及热线胀性能,完全满足用于制作网格模具的硅橡胶要求.     

单/双层水泥基平板的微波吸收性能

依据阻抗匹配原理与电磁波传播规律,提出表层透波、内层吸波的双层法设计,该设计具有电磁波吸收性能的层状水泥基平板结构.研究了硅灰和橡胶粉对表面层阻抗匹配的影响;同时还对碳纤维、钢纤维、碳纤维与铁氧体粉复合以及钢纤维与碳纤维复合作为内层吸收剂时,水泥基平板材料在8～18GHz频段内的吸波性能进行了研究.结果表明:硅灰和橡胶颗粒可以明显地改善水泥平板与自由空间的阻抗匹配:与单层相比,在相同碳纤维掺量时,双层吸波砂浆反射率下降-3dB左右;30%质量分数铁氧体与碳纤维复合作为吸波材料的损耗层的吸收剂,反射率在-10dB以下(12.5～18.0GHz),且随着入射频率的增加反射率下降.     

Recent advances and prospect of cobalt based microwave absorbing materials

With the advances and extensive application of electromagnetic (EM) waves in electronic and communication devices. EM pollution has been identified as a threat to human health whereby EM interference also affects the proper functioning of electronic devices. Therefore, the fabrication of novel microwave absorbing materials (MAMs) has become important to mitigate EM pollution and protect humans as well as other nearby electronic devices. The use of sole cobalt as MAM has gained significant attention due to its EM properties and suitable saturation magnetization. However, large density, eddy current loss, and poor corrosion resistance are some of the factors that hinder its practical application as an ideal MAMs. In this paper, recent advances towards overcoming these challenges have been reviewed. In particular, ways of regulating the morphology and optimizing the EM properties of cobalt-based MAM. Furthermore, fabrication of high-performance lightweight absorbers with hierarchical structures and formation of cobalt-based hybrid MAM with other lossy materials are discussed. Several factors affecting the microwave absorption performance of cobalt-based MAM are further discussed. Finally, the present limitations as well as prospects are put forward to give a new insight into the design of improved cobalt-based MAM.     

吸波复合材料预浸料制备工艺研究

对吸波复合材料预浸料制备工艺特性及存在的问题进行了分析,借鉴以玻璃布生产蜂窝夹芯材料时所使用的机械化涂胶工艺,提出了由双槽辊式涂胶法与喷涂浸胶法组合而成的机械化预浸料制备工艺。工艺特性分析表明:喷射涂胶法能够有效地解决吸收剂材料在预浸料中均匀分布、含量可控的技术难题,达到材料产品吸波性能稳定、可靠的质量要求;双槽辊式涂胶法使得纤维布的浸胶效果良好,辊压复合而成的夹芯结构预浸料片铺层工序简化,质量可靠性高。     

PVA-g-PBA在氯醇型遇水膨胀橡胶中的增容作用

选择亲水性的氯醇橡胶和交联聚丙烯酸盐为主要原料，以ＰＶＡｇＰＢＡ两亲性接枝共聚物为增容剂，白碳黑为补强剂，聚乙二醇为吸水促进剂，利用多组分机械共混技术，制备了接枝增容型遇水膨胀橡胶；用扫描电镜对其做了表征；从吸水动力学数据出发，研究了重量吸水率和体积膨胀率以及重量损失率与增容剂含量之间的关系；探讨了吸水之后试样的第二次吸水行为；对增容样品吸水前后的力学性能进行了测试。     

Carbon black/silicone rubber blends as absorbing materials to reduce Electro Magnetic Interferences (EMI)

Summary In this work the microwave absorbing properties of carbon black/silicone rubber blends were investigated in the frequency range 0.2÷6.0 GHz, varying the carbon black contents. In particular, the permittivity of the samples was measured by a network analyzer and then the experimental data were fitted as function of microwave frequency and carbon black content, ε^*=ε^*(f,C). The reflection loss for a layer of blend attached on a metal plate, which is related to the shielding effectiveness, was simulated as function of frequencies and of layer thickness for some values of carbon black content, and the simulation results were summarized in contour plots. These plots can be used to select thickness and carbon black content necessary to achieve the desired shielding effectiveness for a given frequency.     

Electromagnetic and microwave absorption properties of FeSiAl and flaky graphite filled Al2O3 composites with different FeSiAl particle size

The increasing electromagnetic interference problems have drawn much attention to microwave absorbing materials. To satisfy the needs of practical application, FeSiAl and flaky graphite filled Al₂O₃ composites were sintered by hot-pressing for microwave absorption application. The effect of FeSiAl particle size on the electromagnetic and microwave absorption properties was investigated in the X-band (8.2–12.4 GHz). The results show that the dielectric properties enhance significantly with increasing FeSiAl particle size, which is attributed to the increased interfacial polarization and conductance loss. As a result of the favorable impedance matching and appropriate electromagnetic attenuation, the reflection loss (RL) of the composites filled with 25–48 μm flaky FeSiAl achieves -15.2 dB at 10.6 GHz and the effective absorption bandwidth (RL < -10 dB) is 1.2 GHz in 10.0–11.2 GHz with a matching thickness of 1.0 mm. It indicates that FeSiAl and flaky graphite filled Al₂O₃ composites are potential candidates for thin-thickness microwave absorbing materials, and the microwave absorption properties can be enhanced by adjusting absorbent particle size.     

室温硫化聚苯乙烯接枝改性硅橡胶的研究

以端羟基聚苯乙烯接枝改性聚二甲基硅氧烷(PS-PDMS)为基胶,加入气相法白炭黑、正硅酸乙酯和二月桂酸二丁基锡,配成脱醇型双组分室温硫化聚苯乙烯接枝改性硅橡胶。研究了PS-PDMS的结构、力学性能和耐高温性能。29Si NMR和1H NMR分析证实,PS-PDMS的结构是以交替排列的Si—O键为主链、侧链为部分甲基被聚苯乙烯取代的接枝共聚物。相比甲基硅橡胶,PS-PDMS硫化胶的力学性能显著提高,耐热性大幅下降。未补强PS-PDMS硫化胶的拉伸强度在2 MPa以上,拉断伸长率在120%以上;气相法白炭黑用量在30份时,PS-PDMS硫化胶的拉伸强度在5 MPa以上;PS-PDMS硫化胶在热质量损失率为5%和20%时的温度分别比甲基硅橡胶低60℃和118℃。