复合材料多频选择性天线副反射面的研制

针对S/X/Ku/Ka四频段选择性天线副反射面的技术要求,从蒙皮材料、夹芯材料和粘接材料的选材方面,选出适合四频段等多频段的透波材料体系。通过对曲面振子成型工艺和副反射面成型工艺优化,掌握了工艺稳定性好、成品率高的高精度曲面偶极振子成型技术。最终成功研制出四频段选择性副反射面,其型面精度为0.08mm(r.m.s.),S和Ku频段的透射传输损耗均小于0.25dB。     

玻璃纤维与碳纤维混杂复合材料的拉伸及低速冲击性能研究

本文采用真空辅助树脂渗透成型(VARI)工艺成型了0°/90°玻璃纤维经编织物和0°/90°碳纤维经编织物不同混杂比的复合材料板,并探讨了混杂比、混杂方式等因素对碳-玻纤混杂纤维复合材料的拉伸性能及低速冲击性能的影响。研究结果表明:少量碳纤维的加入便可很好地改善纯玻璃纤维材料的拉伸和冲击性能;同种混杂比下,玻璃纤维铺覆表面的层间混杂结构拥有最好的拉伸性能;对于低速冲击性能来说,随着试样中碳纤维含量的增加,冲击能降低,扩展能降低,韧性指数降低,冲击后剩余压缩强度增大;碳纤维、玻璃纤维含量相接近时,玻璃纤维铺覆表面的层间混杂结构表现出较好的抗低速冲击性能;碳纤维、玻璃纤维含量相差较大时,玻璃纤维铺覆表面的夹芯结构的抗低速冲击性能较好。     

芳纶纤维复合材料在天线工程中的应用

简要介绍芳纶纤维的性能和特点，以及芳纶纤维复合材料在雷达天线罩、双频选择反射器、轻型结构天线及特种电路基板等方面的国内外应用情况，指出了我国应着重研究与芳纶纤维复合的高介电性能的树脂体系，提高芳纶复合材料的层间强度，并扩展芳纶纤维与其它纤维的混杂应用。     

高强高模聚乙烯纤维植物纤维纸基复合材料制备及性能

以高强高模聚乙烯（UHMWPE）短纤维和针叶木浆为原料，通过湿法成型技术结合树脂浸渍热压方法制备了UHMWPE纤维纸基复合材料，研究了原纸制备工艺和浸渍热压工艺对UHMWPE纤维纸基复合材料性能的影响。结果表明，当UHMWPE纤维与针叶木浆质量比为7∶3、针叶木浆打浆度为58°SR、酚醛树脂水溶液质量分数为10%、上胶量为44%、热压工艺为15 min、10 MPa、130℃时，制得的UHMWPE纤维纸基复合材料性能较好。当原纸经过浸渍热压后，所制备的UHMWPE纤维纸基复合材料抗张指数为59.11 N·m/g，与原纸相比抗张指数提高了6.9倍，表面变得更光滑，同时具有较低的介电常数（约1.97）、介质损耗因数（0.45×10–2）和较好的热稳定性。     

CF／AI复合材料槽形构件制备技术研究

采用真空反压液相浸渗工艺，以碳纤维M40J增强5A06为研究对象，研究了预制件制备工艺中热去胶过程和超声混杂过程对纤维束丝的物理损伤和化学损伤的程度，纤维束丝分散技术对槽形构件成型及性能的影响。结果表明，热去胶温度和超声分散距离对纤维强度保留率均有显著影响，SiC颗粒可以起分散作用，有利于减少浸渗阻力。与未经颗粒分散的复合材料相比，经过5wt％SiC 3wt％淀粉溶液的分散后，复合材料的体积分数由63．2％降低到51．6％，而复合材料的拉伸强度提高了约59MPa，达到651MPa，密度为2．15g／cm^3。     

混杂纤维复合材料力学性能及其低速冲击性能研究

采用热压成型工艺制备单一碳纤维、碳纤维/玻璃纤维(CF/GF)和碳纤维/Kevlar纤维(CF/KF)均质和非均质混杂增强环氧树脂基复合材料,通过三点弯曲、层间剪切、低速冲击及冲后压缩性能测试,研究纤维组分、混杂结构和混杂比对复合材料力学性能及低速冲击性能的影响。结果表明,单一碳纤维复合材料力学性能最佳,其弯曲模量、弯曲强度和层间剪切强度分别达到66.16 GPa、830.35 MPa和42.73 MPa,而CF/GF混杂结构性能总体优于CF/KF混杂结构,内层混杂结构性能优于外层混杂结构;单一碳纤维复合材料低速冲击性能较差,其冲击损伤凹坑深度最高可达混杂结构的3.5倍,对应的分层阈值为2 723.53 N;CF/KF均质混杂结构的剩余压缩强度最大,而单一碳纤维复合材料则最小,对应数值分别为0.92和0.79。     

某雷达天线反射器的轻量化研制

本项目采用化学蚀刻法制作副反射器栅面图形替代原来的绷丝工艺;用高强度聚氨酯泡沫、J-164填充胶、低密度纤维粉等材料制作天线反射器法兰和加强筋部分;采用一体化成型法兰的方法既节约了两套法兰模具、缩短了天线制作周期,又减轻了天线的重量,采用合理的后处理工艺使天线反射器的型面精度达到图纸要求。     

冶金炉窑用高强型煤黏结剂优配的实验研究

以湖南金竹山无烟煤为原料，采用正交实验法对冶金炉窑用型煤复合黏结剂各组分的配比及型煤成型的主要工艺参数进行了实验研究．结果表明，镁基黏结剂和成型压力对型煤的抗碎性能影响显著．型煤黏结剂各组分相对于原料煤粉的最优配比为：镁基黏结剂取4％，生物质纤维取1％，固化剂取0．6％，减水剂取0．12％．型煤成型的最佳工艺参数为：成型压力20kN，成型水分17％，烟煤掺量10%，煤料粒度组成：3mm～2mm颗粒为8％，2mm～1mm为12％，1mm～0．5mm为10％，0．5mm以下为70％．评估了该复合型煤黏结剂的成本，分析了其作用机理．     

天然植物纤维素纤维/聚乳酸复合材料研究进展

综述了使用不同植物纤维,如棉麻纤维、竹木纤维、农作物秸秆纤维等单一或者混杂纤维素纤维增强聚乳酸(PLA),并运用不同成型工艺和处理手段改善复合材料性能的研究进展,展望了天然植物纤维素纤维增强PLA复合材料的未来发展趋势。     

连续纤维增强PEEK增材制造力学性能与成型质量优化

针对连续纤维增强聚醚醚酮(PEEK)复合材料增材制造中的界面结合差、制件精度不高等技术瓶颈,基于多热力场耦合作用下的连续纤维增材制造成型工艺,实现了典型样件的3D打印制备.基于正交实验设计,并通过微观形貌表征和力学性能测试,探究了喷头温度、打印速度和分层厚度对打印制件的表面粗糙度和弯曲性能的影响规律,获得连续纤维增强P...     

Fabrication and characterization of polymer composites surface coated Fe3O4/MWCNTs hybrid buckypaper as a novel microwave‐absorbing structure

A naval hybrid buckypaper was fabricated by vacuum filtration method with monodispersion solution of Fe₃O₄ decorated Multiwalled carbon nanotubes (MWCNTs). The morphology, element composition and phase structure of hybrid buckypaper were characterized by field‐emission scanning electron microscope, energy dispersive spectrometer, and X‐ray diffraction. The microwave absorption and complex electromagnetic properties of the composites surface coated MWCNTs buckypaper (or Fe₃O₄/MWCNTs hybrid buckypaper) have been investigated in the frequency range of 8–18 GHz. The results indicate that the microwave absorption properties of composite structure have been evidently improved due to the Fe₃O₄/MWCNTs hybrid buckypaper' high magnetic loss and suitable dielectric loss properties. The reflection loss of composite surface coated Fe₃O₄/MWCNTs hybrid buckypaper (with a matching thickness d = 0.1 mm) is below ?10 dB in the frequency range of 13–18 GHz, and the minimum value is ?15.3 dB at 15.7 GHz. Thus, Fe₃O₄/MWCNTs hybrid buckypaper can become a promising candidate for electromagnetic‐wave‐absorption materials with strong‐absorption, thin‐thickness and light‐weight characteristics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41974.     

EMW absorption properties of in-situ growth seamless SiBCN-graphene hybrid material

A three-dimensional graphene/SiBCN hybrid composite was prepared by mixing and annealing Polyborosilazanes and sugar at 1200?°C. In this regard, the interface between the ceramic and the graphene formed a stable chemical bonding such as C-B-N, not physically absorbed as traditional meaning. Compared with the purity SiBCN ceramic, the hybrid material possessed a significant improvement on electromagnetic wave (EMW) absorption properties. When the thickness of the hybrid composites fixed on 2.5?mm, the maximum reflection coefficient (RC) increased from 1.36 to 24.24?dB and the bandwidth over 10?dB increased from 0 to 5.2?GHz. In addition, the bandwidth over 10?dB covered the whole X band when the thickness reached 3?mm. In short, this simple method was deemed to be a useful technology to fabricate a unique structure with excellent EMW absorption properties.     

壳核结构SiC/C纤维的制备与吸波性能的研究

采用活性碳纤维转换法制备了壳核结构SiC/C纤维,采用拉曼光谱、SEM、XRD以及热重分析等测试方法对比研究了生成SiC的厚度对壳核结构SiC/C纤维样品的热重及吸波性能的影响。结果表明:包裹SiC壳层后样品吸波性能得到提高,样品厚度为3.0 mm时,保温4 h样品的最小反射损耗在8.24 GHz处达到-17.22 dB,低于-10 dB(90%的电磁波被吸收)的频宽在2.0 mm处达到4.8 GHz(11.12~15.92 GHz);保温3 h样品的最小反射损耗在8.23 GHz处达到-14.45 dB,低于-10 dB(90%的电磁波被吸收)的频宽在2.0 mm处达到4.56 GHz(10.88~15.44 GHz);且随着SiC含量的升高,试样微波吸收性能有所增强;制备的壳核结构SiC/C纤维样品起始氧化温度提高了150 ℃以上,并且最终残余质量在50%左右,即包裹SiC纤维后样品的抗氧化能力大大提高。     

Synthesis and Optical Properties of Poly(BPDA-ODA)/Silica Hybrid Thin Films

Poly(BPDA-ODA)/silica hybrid optical thin films were synthesized using a sol-gel reaction combined with spin coating and multi-step baking. The hybrid thin films were prepared by the precursors of aminoalkoxysilane capped poly(BPDA-ODA) amic acid and tetramethoxysilane (TMOS). Highly transparent hybrid thin films were obtained at a silica content of 0–51.9 wt%. The prepared hybrid thin films showed homogeneous structures and excellent surface planarity. The refractive index of the prepared hybrid thin films decreased linearly with increasing the silica content while the Abbe number showed the opposite trend. The prepared hybrid films also exhibited a much smaller optical birefringence than the parent poly(BPDA-ODA) because of the reduction of the rigid backbone by incorporating the silica moiety. Optical planar waveguides were prepared from the prepared hybrid thin films. The optical losses of the planar waveguides at 1310 nm were in the range of 0.5–1.3 dB/cm, which were reduced significantly by increasing the silica moiety. The reduction of the C–H bonding density and excellent surface planarity by incorporating the silica moiety explain the trend of optical loss. These results suggest that the prepared polyimide-silica hybrid thin films have potential applications for optical devices.     

褐煤干燥成型工艺技术综述

褐煤干燥成型技术是将成本低廉的富含水分的褐煤在一定温度下经脱水后转化成为具有类似烟煤性质的提质煤。提质后的褐煤更有利于综合利用、运输和贮存,且具有可观的经济价值。介绍了国外7种褐煤干燥工艺技术和褐煤热压成型技术;着重论述了管式间接干燥工艺和高压热压成型工艺的干燥过程、成型过程、工艺特点及优缺点;通过工艺设计数据、物料衡算基准和关键设备配置,例举了褐煤干燥成型工艺设计应用实例;分析和论证了褐煤成型过程的性能保证和安全性保障。对褐煤干燥成型生产装置进行了技术经济评价,结果表明：建设1套百万吨级的褐煤干燥成型工厂,其建设投资约为3.8亿元,型煤加工成本约为60元/t。     

Easy synthesis of a nanostructured hybrid array consisting of gold nanoparticles and carbon nanotubes

A nanostructured hybrid consisting of a high-density and uniform assembly of gold nanoparticles (AuNPs) on carbon nanotubes (CNTs) was prepared using easy methods. The pyrolysis of iron(II) phthalocyanine (FePc) on a Si substrate under an atmosphere of hydrogen/argon was used to produce multiwalled carbon nanotubes (MWCNTs) with 12 nm in diameter and 4 μm in length. Then, Au nanocolloid solution, which contained dodecanethiol-capped Au nanoparticles synthesized by solution chemical method, was deposited on the synthesized CNT array and heated at 300 °C for 1 h under Ar. The synthesis temperature of CNT governs the AuNP-CNT hybrid structure and surface nitrogen concentration from decomposition of FePC. CNTs synthesized at 800 °C exhibit the finest particle size and most homogeneous dispersity of assembled AuNPs in comparison to hybrids whose CNTs are synthesized at other temperatures. These features are considered to correlate with the surface nature of the grown CNT; good dispersity of AuNPs on CNT results from interaction between the thiolate molecules capped on the AuNPs and the N atoms doped into the grown CNT. Assembling AuNPs to CNT contributes the electrical conductivity enhancement of the CNT hybrid array.     

活化碳纳米管的孔结构及微波吸收性能的研究

以KOH为活化剂对碳纳米管进行活化处理，将碳纳米管的比表面积从24．5m^2/g提高到360．1m^2／g，孔容从0．051cc／g提高到0．572cc/g。对碳纳米管的微波吸收性能进行测试，研究结果发现，未活化碳纳米管在9．91～14．16GHz范围内对电磁波的反射率低于-5dB，最大衰减峰值为8．57dB；活化碳纳米管在5．37～18GHz范围内对电磁波的反射率低于一5dB，在6．48～10．88GHz范围内对电磁波的反射率低于一10dB，最大的衰减峰值达到22．58dB。通过比较得出，活化能够有效地提高碳纳米管的微波吸收性能。产生的原因是由于活化碳纳米管具有大的比表面积和丰富的孔结构，电磁波在这些孔结构中不断的被反射、漫射而逐渐衰减。     

不锈钢表面有机-无机复合膜的制备及其抗海水腐蚀性能

以多巴胺修饰304不锈钢为基体,采用溶胶凝胶法和自组装成膜法制备了SiO2基、TiO2基和SiO2-TiO2混合基有机-无机杂化涂层。探讨了钛酸四丁酯、正硅酸乙酯和11-巯基十一烷酸(MUA)在不锈钢基体上的成膜性和成膜后的抗腐蚀性能。借助金相显微镜观察了不锈钢基体上的杂化膜的显微形貌,塔菲尔曲线和电化学阻抗谱对比分析了杂化膜的抗腐蚀性能。结果表明,MUA和TiO2、SiO2能复合成膜,膜的致密性好,具有可重复性,且引入TiO2和SiO2后,其抗腐蚀性能有较大幅度提高。     

PTT预取向丝的生产工艺

结合聚对苯二甲酸丙二醇酯(PTT)的特性,综述了PTT预取向丝的生产工艺及其后加工技术。PTT的POY纺丝完全可以适应PET和PA的高速纺丝设备,经过认真细致的工艺调试,并对纺丝装备作一些适当的改造,可以实现PTT预取向丝的工业化生产,制得成形良好、性能优异的PTT预取向丝,以便后加工的顺利进行。     

In-situ growth of bamboo-shaped carbon nanotubes and helical carbon nanofibers on Ti3C2Tx MXene at ultra-low temperature for enhanced electromagnetic wave absorption properties

The potential of two-dimensional layered MXenes in electromagnetic wave (EMW) absorption needs further development. Herein, we carried out the in situ growth of carbon nanotubes (CNTs) on the surface of Ti₃C₂T_x MXene at ultra-low temperature via chemical vapor deposition. The obtained CNTs exhibited a bamboo-like structure and were accompanied by helical carbon nanofibers. The ultra-low temperature solved the problem that the high temperature required in the traditional CNT growth process would destroy the structural integrity of MXene. The lush CNT forest cross-linked the MXene layers, transforming the two-dimensional layered structure into a three-dimensional conductive network, providing abundant conductive channels for carriers, optimizing the impedance matching of the CNT/MXene hybrid, and resulting in a significant dielectric loss. The as-prepared CNT/MXene hybrid exhibited a minimal reflection loss of ?52.56 dB (99.9994% EMW absorption) in the X-band. This work proposes a new idea to enhance the EMW absorption properties of Ti₃C₂T_x MXene and fabricate high-performance MXene-based EMW absorbers.