中空夹芯织物预浸料的制备与性能表征

采用不饱和树脂与中空夹芯织物进行复合制备中空夹芯织物预浸料,研究中空夹芯织物预浸料的制备工艺,并对中空夹芯织物预浸料的站立性、中空复合材料的力学性能、电性能进行表征。结果表明,高度为3 mm的中空夹芯织物预浸料的树脂含量为50%时站立性最好,预浸料固化后中空复合材料的拉伸强度达40.04 MPa,压缩强度达6.63 MPa,介电常数为1.9,损耗角正切值为0.006。     

PU/ATH纳米复合材料的击穿和介电性能

用原位聚合的方法得到聚氨酯/氢氧化铝(PU/ATH)纳米复合材料,研究了ATH含量对PU/ATH纳米复合材料工频击穿场强、正负极性直流击穿场强、不同频率下的相对介电常数和介质损耗角正切值的影响。结果表明,PU/ATH纳米复合材料中ATH质量分数未超过3%时,随ATH含量增加,PU/ATH纳米复合材料的工频击穿场强、正负极性直流击穿场强增加,PU/ATH纳米复合材料的相对介电常数和介质损耗角正切值降低;ATH质量分数超过3%后,随ATH含量分数的增加,PU/ATH纳米复合材料的工频击穿场强、正负极性直流击穿场强开始降低,PU/ATH纳米复合材料的相对介电常数和介质损耗角正切值增加。ATH改性的PU其相对介电常数和介质损耗角正切值高于纯PU的,且两者趋势相同。     

石英纤维布/J-284PD氰酸酯树脂复合材料的制备与性能

采用热压罐成型的方法制备了石英纤维布/J-284PD氰酸酯复合材料,并验证了其力学性能、介电性能和耐湿热性能。结果表明:中温固化的石英纤维布/J-284PD复合材料,其介电性能、力学性能和耐湿热性能优异,其中拉伸强度为630 MPa,层间剪切强度为58.8 MPa,介电常数为3.1,损耗角正切为0.003;经过10 d湿热试验后,性能最大仅下降10%。     

改性SiC短切纤维体积分数对SiC_(sf)/LAS复合材料介电性能的影响

以改性SiC短切纤维为添加剂,用热压法制备了SiCsf/LAS复合材料,考察了纤维的显微结构以及纤维和复合材料在8.2～12.4GHz频率范围内的微波介电性能。结果表明,当SiC纤维的体积分数为2.92时,纤维混合体介电常数实部、虚部最大,分别为38～25、40～20。高复介电常数的SiC纤维使SiCsf/LAS复合材料比LAS具有更高的介电常数,材料中无富碳界面层的形成。当SiC纤维的体积分数为3时,复合材料介电常数实部、虚部以及损耗角正切值最大,其均值分别为58、25和0.45。     

5528氰酸酯树脂基玻璃纤维增强复合材料性能研究

本文对新型的5528改性氰酸酯树脂基玻璃纤维增强复合材料的耐热性能、力学性能、耐湿热性能、介电性能进行研究，结果表明：5528氰酸酯树脂基玻璃纤维增强复合材料具有良好的力学性能和介电性能。其中石英玻璃纤维增强复合材料的介电常数为3．40，介电损耗正切值为0．00393，并且对频率显示出优秀的稳定性；而高强玻璃纤维增强复合材料的介电损耗正切值为0．00925，远远优于环氧和双马树脂基复合材料。5528氰酸酯基玻璃纤维复合材料适合高性能透波材料或高频印刷电路板应用。     

环氧树脂/石英纤维透波复合材料制备

为改善环氧树脂的介电性能及提升石英纤维的界面性能,使用缩水甘油醚基笼型倍半硅氧烷(G–POSS)和γ–氨丙基三乙氧基硅烷(KH–550)分别对环氧树脂和石英纤维进行改性。利用差示扫描量热法研究改性后环氧树脂的固化过程,并通过外推法确定了其固化工艺,根据固化工艺制备环氧树脂/石英纤维复合材料,分别对该复合材料的热稳定性、介电性能和弯曲性能进行表征,结果表明,使用G–POSS和KH–550改性后的环氧树脂/石英纤维复合材料热稳定性、介电性能和弯曲性能达到最佳,初始分解温度达到369.59℃,常温下在12~18 GHz的介电常数稳定在3.2~3.5之间,介电损耗角正切值在0.005~0.02之间,弯曲强度达到376.4 MPa,弯曲弹性模量为21.7 GPa。     

透波材料的高温介电性能测试与分析

详细分析了基于终端短路波导法材料高温介电性能的测试方法,给出了几种典型透波材料从室温到1600℃的高温介电性能测试与分析结果。由结果可知,由于表面吸附水和体内物理水的存在,一般在1000℃以前,随着温度升高,水分挥发或蒸发,复合材料的介电常数ε和损耗角正切tanδ会有所减小;当温度升至1000℃,由于材料中所吸附的水分基本挥发完全,ε和tanδ降到最小值;当温度高于1000℃时,由于复合材料在制备过程中会引入微量杂质,随着温度升高这些微量杂质开始电离,并产生粒子电导,所以导致ε和tanδ均有较大幅度的上升。本文实测数据可以用于高超声速电磁窗材料透波性能的研究与应用。     

玄武岩纤维及其复合材料的微波介电性能

考察了玄武岩纤维及玄武岩纤维织物在2~18GHz频率范围的微波介电性能,结果表明玄武岩纤维的介电常数及介电损耗小,玄武岩纤维三轴向布和玄武岩纤维毡的反射损失均小于5d B。采用真空灌注成型法制备了玄武岩纤维-环氧树脂复合材料,采用弓形法测试其在2~18GHz频率范围的反射损耗,结果表明其在整个频段的反射损失均小于10d B,透波性能良好。     

极限工艺条件中温胶膜性能研究

研究了两种典型的中温胶膜——FM73M胶膜和J-95胶膜在三种工艺条件下的滚筒剥离性能及剪切性能。试验发现：两种胶膜的物理性能相近;在标准工艺条件下,两种胶膜的滚筒剥离强度和剪切强度都是最高的,而在极限工艺条件下,两种胶膜的滚筒剥离强度和剪切强度都降低;两种胶膜的介电常数基本一致,J-95胶膜的损耗角正切值低于FM73M胶膜的,具有更好的介电性能。     

改性氰酸酯基复合材料力学和透波性能研究

利用低介电改性剂对氰酸酯树脂进行改性,制备了石英纤维/改性氰酸酯树脂复合材料,利用SEM表征了树脂及其复合材料的断面,并对改性氰酸酯树脂的耐热性能、力学性能、复合材料的力学性能及透波性能进行了研究。结果表明,改性氰酸酯树脂的玻璃化转变温度达到200℃以上,树脂拉伸破坏表现为韧性断裂,拉伸强度、弯曲强度和压缩强度分别在27MPa、69MPa和148MPa以上;改性氰酸酯树脂和纤维的界面结合良好,复合材料的拉伸强度、弯曲强度和压缩强度分别达到447MPa、461MPa和259MPa以上;在0.5~18GHz范围内,介电常数为3.1~3.3,4mm试样的S21小于-1.6d B。     

Material Characterization and Microwave Substrate Applications of Alumina‐Filled Butyl Rubber Composites

Composites of butyl rubber with micron alumina (BRAL) and nanoalumina (BRnAL) have been prepared by sigma mixing. The stress‐strain curves of both BRAL and BRnAL composites show the mechanical flexibility of the composites. The dielectric and thermal properties of both composites were studied as a function of ceramic loading. For 0.1 volume fraction of micron alumina loading, the composites have attained a relative permittivity (ε_r) of 2.82 and loss tangent (tanδ) of 0.0023 at 5 GHz, and for the same volume fraction of nanoalumina content, the composite showed ε_r of 3.15 and tanδ of 0.014 at 5 GHz.     

固化压力对夹层结构力学性能的影响

通过测试不同固化压力下的Nomex蜂窝夹层结构的力学性能，讨论了固化压力对蜂窝夹层结构性能的影响。结果表明，在固化压力0．2－0．5MPa下，夹层结构的平拉强度、平压强度、剪切强度无明显变化，而侧压强度与弯曲刚度则随压力的增大而发生明显的变化。     

聚苯硫醚/钕铁硼复合材料力学与电磁性能

采用熔融共混的方法制备了聚苯硫醚( PPS) / 钕铁硼(NdxFe94?xB6) 复合材料,分析了复合材料的形态、力学性能及电磁性能。结果表明,均匀分散的NdxFe94?xB6粒子与PPS 基体界面结合紧密;与纯PPS 相比,NdxFe94?xB6添加量为50%时,复合体系的拉伸强度、弯曲强度和冲击强度分别提高了100%、44%和800%;但过多的NdxFe94?xB6填充量反而不利于材料力学性能的提升;复合材料的介电常数和磁导率都随含量增加而增大,在高含量下,介电常数虚部随频率明显变大。通过对复合材料反射衰减计算,匹配厚度d=2mm时,复合材料在高频段出现明显的吸收峰,特别是含量50 %时,吸收峰达到-18.3 dB,对应的频率为16.6 GHz。     

Ring compression properties of SiCf/SiC composites prepared by chemical vapor infiltration

SiC fiber reinforced SiC matrix (SiC_f/SiC) composites prepared by chemical vapor infiltration are one of promising materials for nuclear fuel cladding tube due to pronounced low radioactivity and excellent corrosion resistance. As a structure component, mechanical properties of the composites tubes are extremely important. In this study, three kinds of SiC_f preform with 2D fiber wound structure, 2D plain weave structure and 2.5D shallow bend-joint structure were deposited with PyC interlayer of about 150–200?nm, and then densified with SiC matrix by chemical vapor infiltration at 1050?°C or 1100?°C. The influence of preform structure and deposition temperature of SiC matrix on microstructure and ring compression properties of SiC_f/SiC composites tubes were evaluated, and the results showed that these factors have a significant influence on ring compression strength. The compressive strength of SiC_f/SiC composites with 2D plain weave structure and 2.5D shallow bend-joint structure are 377.75?MPa and 482.96?MPa respectively, which are significantly higher than that of the composites with 2D fiber wound structure (92.84?MPa). SiC_f/SiC composites deposited at 1100?°C looks like a more porous structure with SiC whiskers appeared when compared with the composites deposited at 1050?°C. Correspondingly, the ring compression strength of the composites deposited at 1100?°C (566.44?MPa) is higher than that of the composites deposited at 1050?°C (482.96?MPa), with a better fracture behavior. Finally, the fracture mechanism of SiC_f/SiC composites with O-ring shape was discussed in detail.     

Effects of preform structures on the mechanical and ablation properties of C/ZrC-SiC composites

In order to investigate the effects of preform structures on the mechanical and ablation properties of C/ZrC-SiC composites, 3D4X, 3D5X and 3DZC C/ZrC-SiC composites were fabricated with the same process. The mechanical and ablation properties of 3D4X, 3D5X, and 3DZC C/ZrC-SiC composites were investigated. Results showed that the tensile strength (122.26 MPa) and bending strength (233.29 MPa) of 3D5X C/ZrC-SiC composites were the largest, followed by the tensile strength (112.79 MPa) and bending strength (203.03 MPa) of 3DZC composites and the tensile strength (86.22 MPa) and bending strength (137.59 MPa) of 3D4X composites. The mechanical properties of C/ZrC-SiC composites were mainly related to the fiber content in the axis direction and matrix compactness. In terms of ablation properties, 3DZC C/ZrC-SiC composites acted out the worst performance (the linear ablation rates of 0.0293 mm/s and the mass ablation rates 0.00766 g/s), followed by 3D4X composites (the linear ablation rates of 0.0276 mm/s and the mass ablation rates 0.00683 g/s) and 3D5X composites (the linear ablation rates of 0.0175 mm/s and the mass ablation rates 0.00653 g/s), respectively, which were mainly due to the specific ablation angles, thermal conductivities, and ablation oxides contents caused by fiber volume fraction, braided angles, and other forming parameters.     

RF properties of BST–PPS composites

Ferroelectric ceramic–polymer composites provide flexible self-sustaining thin layers with unique electrical and mechanical properties, and thus a novel way to fabricate RF devices. In this work, a composite made of ferroelectric ceramic (barium strontium titanate, BST) and thermoplastic polymer (polyphenylene sulfide, PPS) was studied with various BST loadings up to 70 wt.%. The microstructures exhibited uniform distribution of ceramic particles in the polymer matrix. RF measurements showed that the relative permittivity and loss tangent of the composites gradually increase with increasing BST loading. At 1 GHz a composite with 70 wt.% BST loading had relative permittivity and a loss tangent of 13.5 and 0.0025, respectively.     

Simultaneously improving mechanical and microwave absorption properties of a novel SiCf/SiOC & mullite hybrid ceramic matrix composite

For enhanced mechanical and microwave absorption properties at the same time, the SiC_f/hybrid matrix composites were fabricated by precursor infiltration and pyrolysis (PIP) method with polysiloxane (PSO) ethanol solution, alumina sols and silica sols. As the first layer of the hybrid matrix, the SiOC ceramic was pyrolyzed from PSO solution. The remained hybrid matrix was mullite, which sintered from alumina sols and silica sols. The effects of different content of PSO solution on the morphologies, flexure strength and reflection loss values of composites were studied. Additionally, the XRD patterns, Fourier Transform Infrared (FTIR) and Raman spectrum of hybrid matrix were also investigated. With the increasingly content of PSO solution from 0% to 10 % and 20%–60% in the first infiltration-pyrolysis process, the flexure strength of composites was increased from 175.18 MPa to 301.94 MPa and decreased from 263.33 MPa to 221.30 MPa, respectively. The complex permittivity was increased with the increasing content of PSO solution from 0%–40% due to the free carbon conductive network from excessive SiOC. Moreover, the complex permittivity of SiC_f/hybrid matrix composites with 50 % and 60 % content of PSO solution was reduced due to more open porosity and broken free carbon conductive network. Additionally, the maximum reflection loss values of SiC_f/hybrid matrix composite with 50 % PSO solution were over -60 dB and the effective absorption bandwidth (EAB) of this composite reaches 3.89 GHz in the X band.     

碳布增强聚芳基乙炔新防热材料

本文了新型高碳聚芳基乙炔树脂的成碳率及其碳布增强防热材料成型工艺,对复合材料的性能进行了表征。     

Impact of ZnO Nanoparticles on Dielectric and Optical Properties of Poly (3-hydroxybutyrate) for Electronics Applications

The dielectric and optical properties of pure poly (3-hydroxybutyrate) and ZnO nanoparticle (15–30%)-reinforced poly (3-hydroxybutyrate) composite films were studied. Nanocomposites exhibit improved relative permittivity (ε′?=?4.6720 @ 1?GHz) with acceptable loss tangent (tan δ?ε′?=?4.5). High absorption in ultraviolet region (200–400?nm) was observed for the nanocomposites. From the observation, the prepared biobased composites can be used as a dielectric substrate for microwave applications and coating material for light-emitting diode encapsulation to block ultraviolet rays and to develop ultraviolet-resistive fabrics for textile industry.     

连续碳纤维增强热固性酚醛树脂复合材料的3D打印工艺及性能研究

针对连续碳纤维增强热固性酚醛树脂复合材料3D打印成型工艺的技术难题,本文提出了浸渍-原位预固化-后固化的3D打印成型方案,实现了连续碳纤维增强热固性酚醛树脂复合材料的3D打印成型,并研究浸渍温度对酚醛树脂接触角与表面张力,以及打印工艺对样件形貌和力学性能的影响规律。结果表明:当浸渍温度为40 ℃,预固化温度为180 ℃时,纤维-树脂界面结合效果最佳,原料具备成型条件;当打印间距为0.5 mm时,样件的弯曲强度及模量达到最大值,分别为660.00 MPa和57.99 GPa,层间剪切强度达到20.14 MPa。此连续碳纤维增强热固性酚醛树脂复合材料一体化制备工艺解决了3D打印热固性树脂原位成型难的问题,为制备具有复杂结构的连续纤维增强热固性树脂复合材料提供了参考。