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碳纤维结构吸波材料及其吸波碳纤维的制备 总被引:19,自引:0,他引:19
碳纤维结构吸波材料是一类多功能复合材料,具有承载和减小雷达反射截面的双重功能,是一种非常有发展前途的吸波材料。碳纤维结构吸波材料以其优异的力学性能和隐身特性已大量应用于隐身技术。本文讨论了碳纤维结构吸波的应用,碳纤维结构吸波材料的类型及其结构型式设计,探讨了吸波波对碳纤维进行掺杂改性,制备出吸波性能优良的碳纤维、改变碳纤维的截面形状和大小,对碳纤维进行表面改性以及对碳纤维进行掺杂改性,制备出吸波性 相似文献
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温俊园谢志勇胡海霞张淇 《炭素技术》2020,(3):25-29
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。 相似文献
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高温结构吸波材料集吸波、防热、承载于一体,其发展对实现航空航天器雷达隐身至关重要。连续Si C纤维增强Si C(SiC_f/SiC)高温结构吸波材料具有高温抗氧化、断裂韧性高、阻抗与空气容易匹配等优点,被认为是最有前途的高温结构吸波材料之一。本文主要从SiC纤维预制体、界面层、基体3个方面对SiCf/SiC高温结构吸波材料改性研究现状进行评述,然后介绍SiC_f/SiC高温结构吸波材料介电温度响应特性的研究进展,总结了SiC_f/SiC高温结构吸波材料存在的问题并指明未来潜在的研究方向。 相似文献
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竹材制备SiC多孔陶瓷及吸波性能研究 总被引:1,自引:0,他引:1
以印度竹和竹炭粉为原料,采用溶胶凝胶法和液态渗硅法制备生物基SiC陶瓷块和陶瓷粉,并通过磁性金属担载制备了吸波材料。借助XRD、SEM、RAM反射率测试系统对材料的物相构成、微观构造、吸波反射率进行了分析。结果表明:竹材炭化及陶瓷化后均保持了多孔的骨架结构特征。溶胶凝胶法和液态渗硅法的陶瓷化反应都发生在竹炭孔道侧壁上,且溶胶凝胶法在竹炭孔道内部有硅基陶瓷晶须生成。要提高液态渗硅法竹炭向SiC的转化率和SiC的晶化程度,可以通过提高陶瓷化温度和延长保温时间的方法来实现。无论何种方法,竹炭粉比竹炭块的陶瓷转化率高。另外通过溶胶凝胶法制备的担载磁性金属的竹基陶瓷材料在低频波段有一定的电磁波吸收性能。草刺 相似文献
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将一定尺寸的玻璃纤维片(GF-sheet)填充至矩形活性碳纤维(Activated Carbon Fiber,ACF)电路屏空穴中,制备了GF/ACF电路屏复合材料,研究了GF-sheet尺寸对ACF电路屏复合材料电磁波反射及吸收特性的影响。结果表明,在均匀分布的ACF电路屏空穴中填充相应尺寸的GF-sheet能有效降低复合材料对电磁波的反射特性,增强吸波能力;GF水平排布的反射性能优于垂直排布;当在正方形ACF电路屏空穴中填充边长l=2 cm的GF-sheet时,最低反射值达到-29.8 d B,其吸波性能较未填充GF-sheet的复合材料,其-10 d B以下的最低反射衰减提高了60.4%,达到-21.5 d B,有效带宽有所拓宽;当在长方形ACF电路屏空穴中填充l=2 cm,w=1 cm的GF-sheet,反射衰减最低,最低反射衰减为-16.1 d B,有效带宽为12.1 GHz。 相似文献
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研究了在采用种子乳液聚合法合成具有核/壳结构的改性硅橡胶微粒过程中,作为种子的纯硅橡胶微粒的交联度及其乙烯基含量、表面活性剂种类及其使用浓度,作为形成壳层材料的烯类单体的种类及其用量、以及反应时间和反应温度等因素对生成目的产物的影响。实验结果表明,要得到结构稳定、易分散的具有核/壳结构的改性硅橡胶微粒,需要具有一定交联度和一定数量的乙烯基基团的硅橡胶微粒作为种子,并选用由非离子型表面活性剂和阴离子型表面活性剂组成的复合乳化体系,选用其均聚物具有较高玻璃化温度的烯类单体作为形成壳层的材料,其用量与有机硅部分的用量相当;反应温度50~95℃,反应时间大于7h。 相似文献
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NiFe2O4 powders with double skin structure which shows a length of 5 ?m and curved surface thickness of 0.5 ?m were prepared by thermal decomposition of their oxalate precursors. The NiFe2O4 powders were mixed uniformly with a proportion of paraffin and then pressed to composite samples. The 采用草酸盐沉淀法制备草酸铁镍前驱体,热分解得到长5 ?m、曲面厚0.5 ?m的夹层中空结构NiFe2O4粉末,将其与石蜡按一定比例混合均匀压制得NiFe2O4/石蜡复合物,考察了其电磁参数,计算了其吸波性能. 结果表明,NiFe2O4含量为40%(?)时复合物吸波性能最佳,样品厚度为3.5 mm时,材料在6.66 GHz处反射损失最小,为?52.06 dB,厚度为3.0 mm时,材料在6.98?8.59及9.72?10.84 GHz范围内反射损耗小于?10 dB,有效吸收频宽为2.73 GHz. 相似文献
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使用乙二醇作为稀释剂将硅溶胶稀释,得到不同浓度的硅溶胶溶液,用作涂覆商用碳纤维的原料。碳纤维表面改性后涂覆硅溶胶溶液,取出后在Ar气氛中于1 600 ℃保温30 min,硅溶胶涂层与碳纤维发生碳热还原反应形成SiC覆盖层。对制得的产物进行形貌和结构表征,并根据热力学数据对SiC包覆层的生长动力学和高温扩散机制进行研究。计算结果表明,反应过程为扩散控制。SiC/C纤维比碳纤维有更优异的耐高温氧化性能,为低成本制备新型陶瓷纤维提供可借鉴的思路和热力学依据。 相似文献
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Carbon fiber reinforced SiC composite is a kind of promising high-temperature thermal protection structural material owing to the excellent oxidative resistance and superior mechanical properties at high temperatures. In this work, a novel design and fabrication process of lightweight C/SiC corrugated core sandwich panel will be proposed. The compressive and three-point bending of the C/SiC corrugated sandwich panels are conducted by experiment and numerical simulation. The relative density of as-prepared C/SiC sandwich panel and the density composite material are 1.1 and 2.1 g/cm3, respectively. As the density of the C/SiC sandwich panel is only 52.3% of the bulk C/SiC, suggesting that lightweight characteristic is realized. Moreover, the C/SiC sandwich panel manifests itself as linear-elastic behavior before failure in compression and the strength is as high as 15.1 MPa. The failure mode is governed by the core shear failure and panel interlayer cracking. The load capacity under the three-point bending C/SiC composite sandwich panel is 1947.0 N. The main failure behavior is core shear failure. The stress distribution under the compression and three-point bend was simulated by FE analysis, and the results of numerical simulations are in accordance with the experimental results. 相似文献
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采用化学气相沉积法制备了微螺旋炭纤维(CMCs),研究了其在频率为8.2 ̄12.4GHz范围内的微波介电特性;以环氧树脂为胶粘剂制备了CMCs/环氧复合吸波涂层,并对其吸波性能进行了研究。结果表明,随着CMCs含量的增加,复介电参数实部ε′、虚部ε″和介电损耗tanδ均有所增加,当CMCs含量为1% ̄5%时,ε″和tanδ增幅很小;当CMCs含量为10%时,两者增幅显著增大。ε′表现出高频减小的趋势,同时tanδ表现出高频增大的趋势,这些均有利于实现高频吸波。磁损耗tanξ较小且CMCs含量对其影响不明显。CMCs/环氧复合吸波涂层的反射率随着CMCs含量的增加而明显减小,表现出高频衰减略有增加的趋势,同时出现多吸收峰,这有利于实现宽频吸波。 相似文献
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This study investigated cumulative damage mechanisms of short fiber type C/SiC under compression. To measure mechanical properties (unloading modulus and permanent strain) before fracture, repeated loading–unloading tests were conducted using a strain gage. Damage was observed to assess characteristics of crack density, length, number, and propagation angle. Furthermore, relations between mechanical properties and damage characteristics were elucidated by application of Basista’s equations and by substituting crack densities inferred from damage observations. Stress–strain relations revealed nonlinear behavior. The unloading modulus did not change, but the permanent strain increased. Cracks propagated mainly between fibers, without fiber fracture, connecting other cracks in the direction of orientation 0 deg to 30 deg to the compressive axis. We estimated permanent strain using Basista’s equations and damage characteristics. Estimates roughly agreed with experiment results, suggesting that the permanent strain increase is attributable to closed crack sliding and friction caused by increased crack density. 相似文献
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《Journal of the European Ceramic Society》2023,43(11):4636-4644
To maintain the thermal stability of SiC nanowires during SiC coating fabrication process, carbon and SiC double protective layers were covered on the surface of nanowires. And SiC nanowires with double protective layers toughened SiC coating were prepared by pack cementation. The results showed that after introducing the SiC nanowires with double protective layers, the fracture toughness of the SiC coating was increased by 88.4 %. The coating protected C/C for 175 h with a mass loss of 3.67 %, and after 51 thermal shock cycles, the mass losses of the oxidized coating were 3.96 %. The double protective layers are beneficial to improve the thermal stability of nanowires, leading to good fracture toughness and thermal shock resistance of SiC coating. SiC nanowires consume the energy of crack propagation by fracture, pullout and bridging, leading to an increase in fracture toughness. 相似文献
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C/C composites with SiC columnar pins were fabricated by a recently developed space-holder method. Effects of SiC columnar pins with pins-row spacing of 5 mm and 4 mm on mechanical properties and toughening of C/C composites were characterized and discussed. Corresponding porous C/C composite matrices were also characterized. The results show that introduction of SiC columnar pins not only improves the compressive and shear properties of C/C composites, but significantly affects the PyC texture of the C/C composite matrix. Under identical TG-CVI deposition conditions, the pristine C/C composites (S0), the unidirectional porous C/C composites (S1 and S2), and the C/C composites with SiC columnar pins (S3 and S4) show typical low-textured PyC, high-textured PyC, and medium-textured PyC, respectively. The mechanical properties of unidirectional porous C/C composites with channels-row spacing of 5 mm (S1) are higher than those of unidirectional porous C/C composites with channels-row spacing of 4 mm (S2). Conversely, for the C/C composites with SiC columnar pins, the mechanical properties of samples with columns-row spacing of 5 mm (S3) are lower than those with columns-row spacing of 4 mm (S4). Moreover, the compressive strength P//(load direction parallel to the channel), P⊥ (load direction vertical to the channel), and shear strength of S3 and S4 is respectively higher than that of S1. Therefore, introduction of SiC columnar pins can effectively improve the mechanical properties of composites without significantly changing the density. 相似文献