Detecting Impact Damage in Carbon Fabric/epoxy-matrix Composites by Ultrasonic F-scan and Electrical Resistance Measurement

The status and the variation of electrical resistance of impacted carbon fiber/epoxy-matrix composites were studied by ultrasonic F-scan and electrical resistance measurement The experimental results shows that impact damage energy threshold value of carbon fabric/epoxy-matrix composites can determine by using ultrasonic F-scan. When the impact energy exceeds the threshold value, damage is generated in composites. Electrical resistance of impacted composites is changed owing to the contact of each carbon fiber unit in composites, which cause a change of the series-parallel in conductors. The veracity of detecting impact damage in composites can be improved in this case.

Evaluation of Impact Damage Tolerance in Carbon Fabric/epoxy-matrix Composites by Electrical Resistance Measurement

Impact damage tolerance is provided in intensity design on composites. The compression intensity of impacted composites requires more than 60% of its original intensity. The influence of impact on compressive intensity and electrical resistance of carbon fabric/epoxy-matrix composites was studied in this paper. The experimental results shows that impact can cause damage in composites, degenerate compressive intensity, and increase resistance. The electrical resistance change rate was used as an evaluation indicator of impact damage tolerance of composites. Impact damage, which results from the applying process of composites, can be identified in time by electrical resistance measurement. So, the safety performance of composites can also be improved.

Plasma treatment for enhancement of the sorption capacity of carbon fabric

In this work we carried out an experimental investigation into enhancement of the sorption capacity of carbon fabric using plasma treatment methods.Carbon fabric is based on viscose fiber and is hydrophobic by nature.Enhancement of the fabric sorption capacity is required for its application in medicine.For this purpose,two plasma treatment methods were considered,i.e.atmospheric nonequilibrium radiofrequency(RF)discharge and a vacuum RF plasma source with an external magnetic field.Samples treated by atmospheric discharge demonstrated aging effects during the first week after treatment.The sorption capacity of samples treated by the RF plasma source was stable over the same period and reached values as high as 0.95.Parameters of the beam created by the vacuum RF plasma source were analyzed and dependences of the fabric sorption capacity and specific surface area on plasma treatment time were investigated.We found that sorption capacity reached its maximum value after 30 min of treatment and did not change significantly if processing was continued,while the specific surface area reached its maximum after 3 min of treatment and quickly decreased after that.It was found that the micropore structure of the fabric remained almost the same during plasma treatment.The volume of mesopores in a unit of the fabric mass(specific volume)doubled during the first 5 min of treatment and returned to initial values after 30 min of treatment.The sorption capacity continued to increase even when the specific surface area decreased after reaching its peak value.This indicates the important role of surface functional groups formed on carbon fibers during plasma treatment.This is consistent with the results of x-ray photoelectron spectroscopy analysis showing changes in surface oxidation during plasma treatment.

Effect of Degree of Cure on Sandwich Structural Capacitor Using Ion-Conductive Polymer with Carbon Fabric Skins

Structural capacitors are composite structures that function as energy storage capacitors. An electric double-layer capacitor with a composite structure using a solid polymer electrolyte matrix with a glass fiber fabric separator has recently been developed. In the present study, new foam core sandwich structure is adopted and the effect of the degree of cure is experimentally investigated. Carbon fiber fabric cloth is used as electrodes, and the polystyrene foam core is used as separator. Material system of Poly Ethylene Glycol DiGlycidyl Ether (PEGDGE) with Lithium bisTriFluoromethane Sulfonyl Imide (LiTFSI) and hardener of TriEthylene TetrAmine (TETA) is adopted as ion-conductive polymer matrix. The effect of the cure degree is experimentally investigated by using 100% cure degree, 70% cure degree and 0% cure degree specimens. As a result, the polystyrene foam-core sandwich system is proved to be effective, but the capacitance is not enough because of the lack of surface area of the carbon fiber electrodes. As the remained TETA impedes the movement of Li+ cation in the solid polymer by means of the segment-motion-assisted diffusion process, the low degree of cure causes small capacitance with this material system.

Controllable fabrication of self-organized nano-multilayers in copper–carbon films

In order to clarify the influence of methane concentration and deposition time on self-organized nano-multilayers,three serial copper-carbon films have been prepared at various methane concentrations with different deposition times using a facile magnetron sputtering deposition system. The ratios of methane concentration(CH4/Ar+CH4) used in the experiments are 20%, 40%, and 60%, and the deposition times are 5 minutes, 20 minutes, and 40 minutes, respectively.Despite the difference in the growth conditions, self-organizing multilayered copper-carbon films are prepared at different deposition times by changing methane concentration. The film composition and microstructure are investigated by x-ray photoelectron spectroscopy(XPS), x-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), and high-resolution transmission electron microscopy(HRTEM). By comparing the composition and microstructure of three serial films, the optimal growth conditions and compositions for self-organizing nano-multilayers in copper-carbon film are acquired. The results demonstrate that the self-organized nano-multilayered structure prefers to form in two conditions during the deposition process. One is that the methane should be curbed at low concentration for long deposition time,and the other condition is that the methane should be controlled at high concentration for short deposition time. In particular, nano-multilayered structure is self-organized in the copper-carbon film with copper concentration of 10-25 at.%.Furthermore, an interesting microstructure transition phenomenon is observed in copper-carbon films, that is, the nanomultilayered structure is gradually replaced by a nano-composite structure with deposition time and finally covered by amorphous carbon.

ADSORPTION CAPACITY OF ACTIVATED CARBON FIBER FABRIC IN CYANIDE LEACHING LIQUOR OF GOLD ORES

Adsorption capacity of ACFF in cyanide leaching liquor of gold ores was studied with cyanide leaching liquor of gold ores, containing various kinds of ions. The adsorbed leaching liquor was analyzed by atomic emission spectroscopy and colorimetric method. The contents of various kinds of ions in ACFF were determined with X-ray photoctron spectroscopy. ACFF not only adsorbed gold but also adsorbed arsenic, nickel, zinc, calcium, sulphur, bismuth, copper, iron, silver and cyanide anion. Atomic percentage of C and those of O, N, Zn, Fe increase and decrease respectively with the increase of the layer depth, while those of Ca, Au, Ag keep constant.

Modeling effects of temperature and precipitation on carbon characteristics and GHGs emissions in Abies fabric forest of subalpine

Abies fabric forest in the eastern slope of Gongga mountain is one type of subalpine dark coniferous forests of southwestern China. It is located on the southeastern edge of the Qinghai-Tibet plateau and is sensitive to climatic changes. A process-oriented biogeochemical model, Forest-DNDC, was applied to simulate the effects of climatic factors, temperature and precipitation changes on carbon characteristics, and greenhouse gases （GHGs） emissions in A. fabric forest. Validation indicated that the Forest-DNDC could be used to predict carbon characteristics and GHGs emissions with reasonable accuracy. The model simulated carbon fluxes, soil carbon dynamics, soil CO2, N2O, and NO emissions with the changes of temperature and precipitation conditions. The results showed that with variation in the baseline temperature from -2℃ to ＋2℃, the gross primary production （GPP） and soil organic carbon （SOC） increased, and the net primary production （NPP） and net ecosystem production （NEP） decreased because of higher respiration rate. With increasing baseline precipitation the GPP and NPP increased slightly, and the NEP and SOC showed decreasing trend. Soil CO2 emissions increased with the increase of temperature, and CO2 emissions changed little with increased baseline precipitation. With increased temperature and decreased baseline temperature, the total annual soil N2O emissions increased. With the variation of baseline temperature from -2℃ to ＋2℃, the total annual soil NO emissions increased. The total annual N2O and NO emissions showed increasing trends with the increase of precipitation. The biogeochemical simulation of the typical forest indicated that temperature changes strongly affected carbon fluxes, soil carbon dynamics, and soil GHGs emissions. The precipitation was not a principal factor affecting carbon fluxes, soil carbon dynamics, and soil CO2 emissions, but changes in precipitation could exert strong effect on soil N2O and NO emissions.

IMPROVED FABRICATION METHOD FOR CARBON NANOTUBE PROBE OF ATOMIC FORCE MICROSCOPY(AFM)

An improved arc discharge method is developed to fabricate carbon nanotube probe of atomic force microscopy （AFM） here. First, silicon probe and carbon nanotube are manipulated under an optical microscope by two high precision microtranslators. When silicon probe and carbon nanotube are very close, several tens voltage is applied between them. And carbon nanotube is divided and attached to the end of silicon probe, which mainly due to the arc welding function. Comparing with the arc discharge method before, the new method here needs no coat silicon probe with metal film in advance, which can greatly reduce the fabrication＇s difficulty. The fabricated carbon nanotube probe shows good property of higher aspect ratio and can more accurately reflect the true topography of silicon grating than silicon probe. Under the same image drive force, carbon nanotube probe had less indentation depth on soft triblock copolymer sample than silicon probe. This showed that carbon nanotube probe has lower spring constant and less damage to the scan sample than silicon probe.

An improved fabrication method for carbon nanotube probe

An improved arc discharge method is developed to fabricate the carbon nanotube probe. In this method, the silicon probe and the carbon nanotube were manipulated under an optical microscope. When the silicon probe and the carbon nanotube were very close, 30-60 V dc or ac was applied between them, and the carbon nanotube was divided and attached to the end of the silicon probe. Comparing with the arc discharge method, the new method need not coat the silicon probe with metal in advance, which can greatly reduce the fabrication difficulty and cost. The fabricated carbon nanotube probe exhibits the good property of high aspect ratio and can reflect the true topography more accurately than the silicon probe.

Facile Fabrication of Hierarchical Porous N/O Functionalized Carbon Derived from Blighted Grains Towards Electrochemical Capacitors

The hierarchical porous N/O co-functionalized carbon(HPNOC)was scalably prepared by using the lowcost and renewable blighted grains as the raw material coupled with mild KHCO_3 activation for electrochemical capacitors(ECs).The elemental N was in situ doped in the obtained HPNOC without any N-containing additives.Remarkably,the obtained HPNOC was endowed with a large specific surface area(about 2 624m^2·g^(-1)),high pore volume(about 1.35cm^3·g^(-1)),as well as high-content N/O functionalization(about 1.9%(in atom)N and about 10.2%(in atom)O.Furthermore,the as-resulted HPNOC electrode with a high mass loading of 5mg·cm^(-2 )exhibited competitive gravimetric capacitances of about 373.6F·g^(-1 )at 0.5A·g^(-1),and even about 260.4F·g^(-1 )at a high rate of 10A·g^(-1);superior capacitance retention of about 98.8%at 1A·g^(-1 )over 10 000consecutive cycles;and high specific energy of about 9.6W·h·kg^(-1 )at a power of 500W·kg^(-1),when evaluated as a promising electrode in 6mol KOH for advanced electrochemical supercapacitors.More encouragingly,the green synthetic strategy we developed holds a huge promise in generalizing for other biomass-derived carbon materials for versatile energy-related applications.

Effect of Aramid/Carbon Hybrid on the Tensile Properties of Multilayered Biaxial Weft Knitted Fabric Reinforced Composites

The effects of aramid/carbon on tensile properties of multilayered biaxial weft knitted( MBWK) fabric reinforced composites are analyzed by experiments. The tensile tests are inducted by the SHIMADZU AG-250 KNE universal material testing machine and Aramis V6 digital image correlation( DIC) technique.More specifically,the composite samples own four hybrid ratios(Na∶ Nc= 12∶ 0,8 ∶ 4,6 ∶ 6 and 4 ∶ 8). The results showed that the aramid/carbon hybrid MBWK fabric reinforced composites showed nearly linear response until reaching the maximum load and the inserting yarns distribution on the surface of MBWK fabrics reinforced composites had a great influence on the strain pattern distribution. Besides,the tensile strength,the tensile modulus and the elongation at breakage of 0° samples and 90° samples increased with the decreasing of aramid/carbon hybrid ratio. In a word,the changes of tensile strength, tensile modulus and elongation at breakage have a lot to do with the difference of aramid/carbon hybrid ratio.

熔丝制造3D打印CFRP层内损伤破坏机理与模型研究

为将3D打印技术应用到桥梁工程中,以熔丝制造3D打印碳纤维复合材料锚环为研究对象,开展了材料层内损伤失效机理的基础性研究工作.首先,对锚环进行了张拉锚固破坏试验,明晰材料的损伤失效模式.其次,测试分析了材料的弹性参数及强度参数值,供后续仿真分析使用.最后,通过VUMAT子程序构建了材料的损伤失效本构关系,利用ABAQUS仿真分析软件模拟熔丝制造3D打印碳纤维复合材料锚环的渐进损伤失效全过程,分析其层内损伤失效机理.结果表明:熔丝制造3D打印碳纤维复合材料具有显著的层内损伤现象;选用Hashin损伤起始判据与刚度瞬间退化模型作为熔丝制造3D打印碳纤维复合材料损伤力学模型偏于安全,具有一定的可行性;锚环在高度方向产生纵向裂纹是由纤维拉伸失效导致的.

“无机粒子-无纺布”协同改性碳纤维复合材料及其增韧机理

针对碳纤维复合材料层间性能较差、易发生分层损伤的问题,提出一种采用SiC粒子和热塑性共聚酰胺(PA)无纺布对碳纤维/环氧树脂基复合材料(CFRP)进行增韧改性的技术,在层间构筑一种“无机颗粒/热塑性纤维/树脂基体”多组分多尺度增韧相体系,对比分析改性前后复合材料的Ⅰ型、Ⅱ型层间断裂韧性和耐热性,借助扫描电子显微镜(SEM)和动态热机械分析仪揭示其增韧和耐热性机制。结果表明,与未改性的CFRP材料相比,当SiC填充量(质量分数)为1%、PA无纺布面密度为25 g/m2时,改性CFRP材料Ⅰ型层间断裂韧性(GⅠC)和Ⅱ型层间断裂韧性(GⅡC)分别提高了52.7%和222.6%。无机粒子的阻滞效应、纤维的桥连效应和基体树脂的塑性变形是其主要增韧机制。

玉米芯多孔碳超疏水棉织物的制备及性能

以废弃玉米芯为原料,经氢氧化钾活化,高温炭化制备玉米芯多孔碳(CPC)。对CPC微观形貌进行表征,研究了不同炭化温度对CPC表面形貌的影响。当炭化温度为600℃时,制备的CPC粉末具有均匀的微观多孔粗糙结构。利用低表面能物质聚二甲基硅氧烷(PDMS)对棉织物整理,制备了超疏水棉织物。对整理织物的表面形貌进行表征,研究了不同质量分数的CPC与PDMS整理后棉织物的超疏水性能。结果表明,当CPC质量分数为0.5%,PDMS质量分数为4%时,整理棉织物水滴接触角达到156.9°,具有较好的超疏水、防污及自清洁性能。

机织角联锁变密度复合材料的面外压缩力学特性

为研究变密度结构设计对三维机织角联锁复合材料面外力学性能的影响,设计制备了三维机织角联锁不变密度复合材料、三维机织角联锁经纱变密度复合材料和三维机织角联锁纬纱变密度复合材料。结合扫描电子显微镜、数字图像相关技术和X射线计算机断层扫描等检测技术,对角联锁变密度复合材料的面外压缩力学行为、内部损伤量化和渐进损伤等进行了测试与表征。研究结果表明:上疏下密角联锁纬纱变密度复合材料展现出优异的压缩性能,其压缩比强度比不变密度复合材料高3.40%;同时,上疏下密角联锁纬纱变密度复合材料损伤体积仅为11.64 mm 3,远低于不变密度复合材料的26.90 mm 3。进一步分析得到,不变密度复合材料压缩破坏以剪切失效为主,而上疏下密角联锁纬纱变密度复合材料则为基体开裂。

碳纤维铝基复合材料制备及合金化研究现状

碳纤维铝基复合材料具有优异的抗拉性能、耐磨性和抗疲劳性能等特点,广泛应用于飞行器、军工用品、汽车等领域。针对目前碳纤维铝基复合材料制备成形困难和界面结合性能差等问题,本文论述了近年来国内外各种碳纤维铝基复合材料制备工艺,分析了各种制备工艺的特点,总结了基体合金化对界面反应和润湿性的影响。同时,对碳纤维铝基复合材料的未来发展进行了展望。

碳纤维多轴向织物的特点及其发展趋势

阐述了碳纤维织物的分类及其制备工艺。重点介绍了碳纤维多轴向织物的性能特点及其在航空航天、风力发电、民用等领域的广泛应用,分析了未来碳纤维多轴向织物的发展趋势和市场前景。

澳洲坚果壳活性炭载锌复合抗菌材料的制备及性能研究

以澳洲坚果壳为原料,采用氯化锌活化法制备粉末活性炭作为抗菌材料载体,通过浸渍法将Zn^(2+)负载于活性炭的表面和微孔中,得到活性炭载锌复合抗菌材料。利用碘吸附值、氮气吸脱附、扫描电子显微镜、电感耦合等离子体-发射光谱及抗菌实验对材料进行表征。结果表明:活性炭材料具有多孔结构,比表面积达644.118 m^(2)/g,平均孔径为2.289 nm,碘吸附值为1018 mg/g。以硫酸锌为锌源,炭锌接触时间7 h、炭锌浸渍比1∶25、锌溶液浓度1.0 mol/L时,制备的活性炭载锌复合抗菌材料具有较好的杀菌性能,对大肠杆菌和金黄色葡萄球菌都能达到99.9%的抗菌率。活性炭载锌复合抗菌材料与织物浸渍得到的抗菌织物也具有较好的抗菌效果,展现了良好的应用前景。本研究可为拓宽废弃生物质资源的应用范围提供参考。

中温环氧MF6052高模碳纤维织物复合材料性能研究

以中温环氧树脂为基体,以MF6052高模碳纤维织物为增强材料,通过热熔两步法成功制备了一种预浸料,制备出的预浸料具有良好的物理和工艺性能。并采用模压成型工艺制备了复合材料层压板,复合材料表现出良好的室温力学性能、较高的拉伸模量和优异的疲劳性能,拉伸模量达94.0 GPa,拉伸疲劳强度达353 MPa。相比中温T300级和T800级碳纤维织物预浸料复合材料,拉伸模量分别高出44%和34%,疲劳性能与T800级碳纤维织物预浸料复合材料相当,同时面内剪切性能和层间剪切性能良好,表明研制中温环氧树脂与MF6052高模碳纤维织物界面结合良好,成功实现了中温环氧高模碳纤维织物预浸料的国产化研制。

季铵盐阳离子表面活性剂在涤纶碱减量中的应用

为了降低传统涤纶碱减量中碱剂的用量,采用十二烷基二甲基苄基氯化铵(1227)、十六烷基二甲基苄基氯化铵(1627)、十八烷基二甲基苄基氯化铵(1827)三只季铵盐阳离子表面活性剂作为涤纶织物碱减量促进剂,研究了氢氧化钠和促进剂用量、促进剂分子结构以及保温时间等因素对涤纶织物碱减量的影响,并测试了涤纶织物的减量率,分析比较了碱减量后织物的服用性能与染色性能。结果表明,促进剂疏水链越长,对碱减量促进作用越显著,即促进效果大小为:1827>1627>1227。碱减量过程中,促进剂的使用可以改善涤纶织物减量后的亲水性、白度、强度等,且处理后涤纶织物染色K/S值明显高于传统液碱处理的涤纶织物,说明在达到相同碱减量效果的条件下,促进剂1827的使用可以有效降低碱剂的用量。