Electrografting of poly(carbazole-co-acrylamide) onto several carbon fibers: Electrokinetic and surface properties

Electrografting onto untreated high modulus (HM) and high strength (HS) carbon fibers as well as on electrochemically oxidized HM carbon fibers was carried out under preparative constant current electrolysis conditions by electrocopolymerizing carbazole-acrylamide. The surface morphology of the electrografted carbon fibers was determined by scanning electron microscopy (SEM). In order to obtain at least some information about the relative surface composition of the electrografted fibers energy dispersive X-ray microanalysis (EDX) was applied. For the characterization of chemical composition FTIR reflectance measurements were performed as well. The electrografted copolymer exhibited good thermal stability, which was determined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The efficiency of the electrocopolymerization on carbon fiber surfaces under preparative constant current electrolysis conditions was also supported by electrokinetic measurements.     

Effect of surface state of carbon fiber electrode on copper electroplating from sulfate solutions

The effect of the fiber surface state of a carbon fiber fabric on the parameters of copper electro-plating from a sulfate solution (the copper current efficiency, the electroplating rate, and the deposit distribution in the depth of electrode) is studied. The surface state of fibers was changed by preliminarily polarizing the carbon fiber fabric in electrolyte solutions. The change in the specific conductivity and weight of the carbon fiber fabric, as well as the surface state of oxides and the morphology of the copper deposit, depending on the conditions of electrode polarization was studied.     

连续Cf/Al复合材料板双辊铸轧制备及力学性能研究

本文利用电镀工艺制备了表面镀镍碳纤维,通过双辊铸轧短流程成型工艺成功制备了连续碳纤维增强铝基（Cf/Al）复合材料板,研究了浇注温度对铸轧复合材料板的微观组织、界面特征、断口形貌和力学性能的影响。结果表明,浇注温度为963～983K,轧制速度为2.7m/min,辊缝为2.0mm的条件下可制备出表面平整、无明显表面缺陷的Cf/Al铸轧复合材料板;其中,浇注温度为973K时,碳纤维与铝基体之间界面结合良好;纤维表面金属镍层明显改善了碳纤维与铝基体之间的浸润性,镍镀层还有效抑制了Al4C3脆性相的产生,使Cf/Al复合材料板力学性能大幅提升,其中浇注温度973K铸轧的Cf/Al复合材料板抗拉强度比初始的38.2MPa提高了87.4%。     

Recovery of copper and tin from stripping tin solution by electrodeposition

In this paper, the method of recycling copper and tin by constant-current and constant-voltage electrolysis from the stripping tin solution of tinned copper wastes was studied. The experimental results show that the elements could be deposited on the cathode in turn by different deposition potentials, therefore, the copper and tin were separated by constant-voltage electrolysis but not constant-current electrolysis. In this study, the influence of anode materials was also investigated. Graphite anode is stable without impurities dissolved into the stripping tin solution, while 316 stainless steel anode is dissolved into Fe2？and Fe3？as anodic corrosion, which could decrease the deposition efficiency of tin. The copper and tin in the stripping tin solution are separated orderly by electrodeposition at different voltages using the graphite anode. The recovery rate of copper is up to 100 % at 2.00 V, while that of tin is 80 % at 3.00 V.     

碳纤维复合贴片的界面行为研究

采用低温等离子体法对碳纤维进行表面处理,并在微波固化条件下将碳纤维与环氧树脂复合成形,制得碳纤维复合贴片.采用X射线光电子能谱仪对碳纤维表面的元素组成进行了表征,采用扫描电镜和能量散射光谱(EDS)对碳纤维/树脂界面区的形貌和元素分布进行了表征.结果表明:碳纤维经处理后,其表面氨基官能团的含量增大,有利于纤维与树脂的化...     

Preparation and properties of Cu matrix composite reinforced by carbon nanotubes

Cu matrix composites reinforced by carbon nanotubes(CNTs) were prepared. The effect of carbon nanotubes on mechanical and tribological properties of the Cu matrix composites were investigated. The chemical method for coating CNTs was reported. The morphology of the fracture surfaces and worn surface were examined by SEM.The results show that Cu/coated-CNTs composites have higher hardness, much better wear resistance and antifriction properties than those of the reference Cu alloy (Cu-10Sn) and Cu/uncoated-CNTs composite sintered under the same conditions. The optimal mechanical properties of the composites occurred at 2. 25%(mass fraction) of CNTs. The excellent wear resistance and anti-friction properties are attributed to the fiber strengthening effect of CNTs and the effect of the spherical wear debris containing carbon nanotubes on the tribo-surface.     

吸附EDTA活性炭的电化学再生(英文)

采用吸附饱和EDTA的活性炭作为三维电极反应器中的粒子电极,多次使用后采用电化学方法对其再生。通过对吸附饱和EDTA的活性炭和多次电解使用后的活性炭的红外光谱谱图的分析得出,EDTA被活性炭吸附后产生甘氨酸H2NCH2COOH,通过N—H键生成一种永久性占据活性炭活性点的非催化活性缔合物,导致其催化活性消失,降解效率下降。采用电解方法使活性炭再生,得出活性炭的最佳活化条件为:电流100～300mA,溶液电导率1.39mS/cm,pH值6.0～8.0,电解1h可以使活性炭恢复活性,电解后有机物的残余TOC浓度低于10mg/L(初始浓度为200mg/L)。     

复合材料用碳纤维的表面处理

碳纤维及其复合材料具有高比强度、高比模量、耐高温、耐腐蚀、耐疲劳和抗蠕变等一系列优异性能,为了充分发挥碳纤维的性能,对其进行表面处理非常关键.分别介绍了碳纤维的气相氧化法、电解氧化法、液相氧化法、等离子氧化法、电聚合法、气相沉积法和表面镀层等表面处理方法,并比较了不同处理方法对碳纤维表面结构和性能的影响.碳纤维的表面处理对提高其使用性能是一个重要的保证措施,针对碳纤维不同的使用要求,应采用不同的表面处理方法.通过对比各种碳纤维的表面处理方法得知:目前应用最为广泛的是臭氧化法﹑阳极电解氧化法和等离子氧化法.     

Intercalation of formic acid into carbon fibers and their exfoliation

Intercalation of formic acid in a mesophase-pitch-based fibers was successfully carried out by electrolysis in 50% solution. The formation of intercalation compounds was confirmed by X-ray diffraction (XRD), which showed a broad peak at the interlayer spacing of 0.92 nm. By rapid heating of the intercalated compounds of carbon fibers thus produced up to 1000 °C, exfoliation was occurred instantaneously. Changes of potential was found to depend on electrolysis temperature to prepare intercalation compounds of carbon fibers with formic acid; at the higher temperature potential saturated at the less electrical charge supplied. Suitable synthesis condition of the intercalation compounds was determined to be the current density of 200 A/g at the electrolysis temperature 10 °C. The exfoliation of carbon fibers started at the free end of fibers and proceeds gradually to the fixed end along the fiber axis with increasing charge. This electrolysis behavior suggests that the intercalation of formic acid into the present carbon fibers proceeds from the free end of carbon fibers towards the fixed end with increasing charge.     

碳纤维化学接枝甲基丙烯酸甲酯的研究

目的提高碳纤维与基体树脂间的粘结力。方法对碳纤维表面进行聚甲基丙烯酸甲酯化学接枝改性。首先利用硝酸和硫酸的混酸对碳纤维进行预处理,使表面形成一定反应官能团,再以过氧化苯甲酰(BPO)为引发剂,甲基丙烯酸甲酯(MMA)为单体,通过悬浮法进行聚合。对处理前后的碳纤维进行红外光谱分析、热重分析、显微形貌分析和XPS分析。结果接枝碳纤维的红外光谱在1775.28 cm-1处出现了C O伸缩振动的特征峰;在740℃时的热失重率为6.08%,比未处理时及混酸处理后增加约5%左右。表面形态显示,在碳纤维表面局部地方有PMMA存在;XPS分析结果显示,化学接枝后的碳纤维表面比接枝前有更多的含氧官能团。结论该方法可以使MMA在碳纤维的表面发生聚合反应,以化学键的形式接枝在碳纤维表面。     

Surface Analysis of Ti/Sb-SnO2/PbO2 Electrode after Long Time Electrolysis

主要考察Ti/Sb-SnO2/PbO2电极在Na2SO4溶液中恒电流密度长时间电解后,其电极表面状态的变化情况。通过扫描电镜与元素分析来考察电极表面形貌变化及表面元素分布情况,通过X射线衍射来考察电极表面氧化物的晶型变化情况,通过电感耦合等离子体仪来检测电解液中金属元素的浓度变化。结果表明,在长时间电解后,PbO2电极表面存在氧化物层溶蚀与脱落区域。在电解完成后的电解液中检测到Pb元素,表明电极表面存在Pb元素的溶解。X射线衍射表明电极表面仍然为PbO2层,只是相应的衍射峰强度有所降低。由上述结果推测PbO2电极失效的可能原因是：表层氧化物溶解、脱落以及基体的钝化。     

高铁酸钾电化学合成及其机理研究

采用一种新的铁电极材料制备高铁酸钾,探讨了电解材料、电流密度、电解时间对电流效率的影响,最佳工艺条件为:16mol/L NaOH,J=100mA/cm2,温度35℃,电解时间2.5h,高铁酸根物质的量浓度可达0.2869mol/L.初步研究了该反应的机理,结果表明此铁电极的循环伏安曲线与文献显著不同,尤其在-100mV(vs.HgO/Hg)附近出现明显的阳极氧化峰,可能是Fe(Ⅲ)向Fe(Ⅵ)转化的中间产物FeO34-[Fe(Ⅴ)],此反应加速了Fe(Ⅵ)的生成,提高了高铁酸钾的时空效率.用XRD对高铁酸钾进行了表征,在2θ为30°的位置出现最强的衍射峰,衍射强度为670.     

碳纤维表面生长纳米碳管及其增强的炭/炭复合材料

采用化学气相沉积工艺在碳纤维表面生长了纳米碳管,将此种碳纤维作为增强材料,以中间相沥青为基体炭前驱体采用浸渍炭化工艺制备了炭/炭复合材料.观察了所得复合材料断口的微观形貌,测试了抗弯强度及热物理性能.结果表明,碳纤维表面的纳米碳管可以有效地提高纤维与基体的粘结力,复合材料的抗弯性能提高了50%,而对复合材料的导热性能影响较小.     

TiB2-C复合阴极中碱金属（K、Na）的渗透及其对阴极电解膨胀的影响（英文）

在不同电解条件下,研究纯KF熔体、纯NaF熔体及其复合电解质熔体中,碱金属(K、Na)在TiB2-C复合阴极中的渗透迁移行为及其引起的阴极电解膨胀。揭示影响阴极电解膨胀性能的主要因素,同时对阴极剖面进行元素微区分析。结果表明:在非极化以及不含铝的电解质熔体中,阴极不会发生膨胀;直接放电所生成的碱金属是造成阴极膨胀的主要因素,引起的阴极最大电解膨胀率可达20.40%;含钾电解质熔体中阴极的电解膨胀率远高于不含钾电解质熔体中阴极的电解膨胀率,最高超出35.13%;与纯钾盐相比,复合电解质对阴极的破坏作用降低;此外,无论是在极化条件还是在非极化条件下,含铝电解质熔体中阴极的电解膨胀率均大于不含铝电解质熔体中阴极的电解膨胀率;同时,在非极化条件下电解质熔体中加入铝后比极化条件下电解质熔体中加入铝后所引起的阴极电解膨胀的增加更为明显。     

微米银粉的正交实验法制备与表征

研究了以抗坏血酸为还原剂的液相还原法制备球形微米银粉时的主要因素对振实密度和形貌的影响。实验表明,酸性条件下制备的微米银粉分散性较好。正交实验表明,对银粉振实密度的影响大小的因素依次为底液pH、硝酸银浓度、分散剂PVP用量和实验温度。经过对银粉进行粒度、SEM和XRD等测定表征发现,优化条件下可制备得到振实密度为4.2 g/cm~3,平均粒径2.5μm,分散性良好的类球形银粉。     

碳纤维表面氮化硼涂层的制备

用先驱体转化法,在碳纤维表面制备了涡轮层状氮化硼(t-BN)涂层.用SEM,XRD,IR等测试手段对涂层的结构、形貌进行了表征,并且测试了纤维的单丝拉伸强度.实验证明以硼酸为原料,利用先驱体转化法在碳纤维上成功地制备了连续且均匀的t-BN涂层;在氮气气氛中加入还原性气体,使得氮化硼涂层的热处理温度降低到400℃;碳纤维...     

Nickel and nickel-phosphorous matrix composite electrocoatings

Nickel and nickel-phosphorous matrix composite coatings reinforced by TiO₂, SiC and WC particles were produced under direct and pulse current conditions from an additive-free Watts' type bath. The influence of the variable electrolysis parameters (type of current, frequency of current pulses and current density) and the reinforcing particles properties (type, size and concentration in the bath) on the surface morphology and the structure of the deposits was examined. It is demonstrated that the embedding of ceramic particles modifies in various ways the nickel electrocrystallisation process. On the other hand, Ni-P amorphous matrix is not affected by the occlusion of the particles. Overall, the imposition of pulse current conditions leads to composite coatings with increased embedded percentage and more homogenous distribution of particles in the matrix than coatings produced under direct current regime.     

Si/BDD电极在酸/碱电解条件下的电化学氧化性能变化

目的 探究Si/BDD电极在酸性、碱性2种电解条件下的性能变化特征,阐明BDD电极在酸、碱溶液中电化学氧化性能的变化与失效机理。方法 通过HFCVD技术制备Si/BDD电极,分别在1 mol/L H₂SO₄、1 mol/L NaOH溶液中进行加速寿命实验,以活性蓝19(RB-19)模拟染料废水,进行电化学氧化降解实验。使用扫描电子显微镜、拉曼光谱、接触角测试仪、紫外分光光度计及电化学工作站对电极的表面形貌、成分及电化学性能进行表征。结果 在1 mol/L NaOH溶液中,当电解时间为195 h时,电极表面部分区域发生了明显的脱落现象;在1 mol/L H₂SO₄溶液中,当电解时间达到600 h时,电极表面仍未出现明显的脱落现象,电极表面形貌由清晰转为模糊,晶粒尺寸细化,且在晶界处存在明显的腐蚀现象;在酸溶液中,BDD电极对RB-19的降解效果随着电解时间的延长而提高,而在碱溶液中,其降解效果与电解10 h的降解效果基本一致。结论 与酸溶液相比,Si/BDD电极更易在碱溶液中发生腐蚀。     

微波合成WCx/MWCNTs及其电催化性能研究

目的制备多壁碳纳米管负载碳化钨的纳米复合材料(WC_x/MWCNTs),探索微波加热温度对WC_x/MWCNTs合成的影响规律。方法利用分子自组装技术与微波加热技术相结合,以钨酸钠为W源,制备了WC_x/MWCNTs纳米复合材料。采用X射线衍射(XRD)和透射电子显微镜技术(TEM)对不同条件下制得样品的物相组成、结构及微观形貌进行了表征;采用循环伏安法在酸性环境下测试了WC_x/MWCNTs对氢和CH3OH的电催化性能。结果当微波加热温度为1000℃时,制备的WC_x/MWCNTs纳米复合材料由WC、WC2和C组成,碳纳米管的多壁结构保留较好,碳化钨颗粒均匀地分布在碳纳米管外表面,粒径为20~50 nm。循环伏安测试结果表明,制备的WC_x/MWCNTs在酸性环境下对氢具有一定的催化作用,但对甲醇没有明显的电催化作用。结论通过控制合理的微波加热温度,可制备出碳化钨粒径小、分布均匀、碳纳米管多壁结构完好的WC_x/MWCNTs纳米复合材料。制备的WC_x/MWCNTs在酸性环境下对氢具有一定的催化作用,可作为催化剂载体来负载其他金属制备复合催化剂。     

Microstructure of carbon fiber preform and distribution of pyrolytic carbon by chemical vapor infiltration

The carbon/carbon composites were made by chemical vapor infiltration(CVI) with needled felt preform. The distribution of the pyrolytic carbon in the carbon fiber preform was studied by polarized light microscope (PLM) and scanning electronic microscope(SEM). The experimental results indicate that the amount of pyrolytic carbon deposited on the surface of chopped carbon fiber is more than that on the surface of long carbon fiber. The reason is the different porosity between the layer of chopped carbon fiber and long carbon fiber. The carbon precursor gas which passes through the part of chopped carbon fibers decomposes and deposits on the surface of chopped carbon fiber. The pyrolytic carbon on the surface of long carbon fibers is produced by the carbon precursor gas diffusing from the chopped fiber and the Z-d fiber. Uniform pore distribution and porosity in preform are necessary for producing C/C composites with high properties.