镍基碳纳米管复合薄膜的电沉积技术

本文选用多壁碳纳米管作为增强相材料,采用超声复合空气搅拌及复合电沉积技术.制备了碳管分散均匀,镀层表面平整的连续镍基碳纳米管复合薄膜.经扫描电子显微镜(SEM)观察,超声复合空气搅拌可以有效改善镀层中碳纳米管的分散性和镀层表面平整性.通过选择合适的电流密度和镀液中碳纳米管含量可以调整镀层中碳纳米管的复合量,并同时保持镀层的平整性和镀层中碳纳米管的分散性.在实验测定的几组数据中,当碳管量为6～8g/L,电流密度为5A/dm2,分散剂加入量为6m1～8ml/L,超声复合空气搅拌时,得到表面平整,碳纳米管分散良好的连续致密镀层.用碳硫分析仪测得碳纳米管复合量可达5.7%(体积百分比).     

Ni-Al2O3纳米复合电镀工艺的初步研究

初步研究了复合电镀各工艺条件：电流密度、镀液pH值和温度以及搅拌方式对Al2O3纳米微粒在镍基复合镀层中含量的影响。研究表明：电流密度增大不利于提高镀层中纳米微粒的含量；pH值增大也明显使复合量降低;镀液温度升高，镀层中微粒的复合量随之略有改变；电镀时，加强搅拌或适当改变搅拌方式，可以使复合镀居中的纳米微粒含量提高。还利用扫描电镜及能谱对Ni-Al2O3镀层表面进行了观察与分析。     

温度和搅拌对甲基磺酸亚锡电镀亚光锡的影响

为提高甲基磺酸盐体系镀锡的质量,在甲基磺酸亚锡镀液中加入自主研发的亚光添加剂进行电镀亚光锡,采用电化学试验、Hull槽试验、扫描电镜等考察了温度和搅拌对甲基磺酸盐体系电镀亚光锡的阴极极化行为、镀层形貌、电流密度范围、沉积效率、沉积速度及镀液成分的影响。结果表明:亚光添加剂能够显著提高电镀亚光锡的阴极过电位、改善镀层质量;搅拌镀液可使浓差极化减小,增大了电镀亚光锡的电流密度范围;镀液温度升高,锡沉积电位正移,晶粒变粗,电流密度范围、电流效率和锡沉积速度均有所提高;温度过高(40～50℃)时,随着电镀时间的延长,镀液中Sn2+浓度升高,甲基磺酸浓度下降,镀液成分变化较大,不利于镀液维护及连续生产。     

离心高速电沉积Ni-SiC复合镀层的研究

利用自制的离心高速电沉积实验装置,研究了镀液温度、镀液pH值、电流密度、镀液中SiC浓度和阴极旋转速度对Ni-SiC复合镀层中SiC含量的影响;同时还对镀层中SiC微粒的分布情况及镀层的性能进行了研究。结果表明:温度、电流密度、镀液中的SiC含量及阴极旋转速度对镀层中复合粒子的含量有显著的影响,而pH值对镀层中SiC含量影响不大。利用离心高速电沉积方法能够制备出高体积分数的、微粒分布均匀的Ni-SiC复合镀层。所制备的高体积分数的Ni-SiC复合镀层硬度和耐磨性能优于普通槽镀镀层。     

电沉积法制备碳纳米管/黑镍复合涂层的光学与结构特性

利用复合电沉积的方法在钛合金基体上成功制备出具有优异光学性能的碳纳米管／黑镍复合涂层, 并研究了复合涂层的微观形貌、光学性能以及镀液中碳纳米管浓度和电镀电流密度对光学性能的影响。实验结果表明: 相较于传统电镀方法获得的单一黑镍涂层, 复合涂层的晶粒尺寸明显减小, 形成多孔结构, 表面粗糙程度明显增加。复合涂层对300~2300 nm范围内的入射光吸收率达到98%左右, 在2.5~20 μm范围内的红外吸收率达到94%, 远远高于传统单一黑镍涂层。复合涂层的太阳吸收比会随着镀液中碳纳米管浓度与电镀电流密度的增加呈先增大后减小的变化规律。     

间歇搅拌对铁基复合镀层中微粒含量的影响

１ 前 言 镀铁层具有硬度高、耐磨性好、成本低、镀液排出物对环境污染小等一系列优点,可用于机器零部件的修复,使磨损报废的零件修复完好重新使用。若在铁镀层中同时沉积高硬度的ＳｉＣ或Ａｌ_２Ｏ_３颗粒,形成一种优质耐磨的铁基复合镀层,将大大延长零部件的使用寿命。复合镀层的性能与其中所含固体颗粒的量密切相关。影响镀层中颗粒含量的因素通常有电解液中颗粒的含量、电流密度、搅拌因素、镀液温度以及镀液的pＨ值等。其中电流密度和搅拌因素是影响复合电沉积的两个主要因素,即电极表面的静电力场和镀液流速将对复合电沉积产生重…     

Cr-Fe-ZrO2复合镀工艺效果探讨

目前,国内外尚未见有关Cr-Fe-ZrO2复合镀层制备的报道。介绍了Cr-Fe-ZrO2复合镀的工艺技术,研究了阴极电流密度、镀液温度、镀液pH值及电沉积时间对复合镀层厚度和外观的影响。利用扫描电镜观察了镀层的表面形貌,用能谱分析了复合镀层的成分,测试了复合镀层与基体的结合力和耐蚀性能。结果表明:当阴极电流密度为14 A/dm2、镀液温度为25℃、pH值为2.0、电沉积30 m in时,可以获得光亮、准镜面、厚度约7.5μm的复合镀层;镀层与基体结合良好,耐腐蚀性好;镀液稳定性较好,静置360 d后电镀的重现性能较好。     

镍基夜光颜料发光复合镀层的研究

研究了用瓦特镀镍淤电沉积夜光颜料发光复合镀层的工艺，讨论了镀液中阴极电流密度、夜光颜料微粒含量、电镀温度、pH值以及搅拌速度对镀层中夜光颜料复合量的影响。结果表明，选择适当的工艺参数可以获得结合力强、耐 性好、发光强度高的镍基夜光颜料发光复合镀层。     

快速电沉积法制备镍基金刚石复合镀层EI北大核心CSCD

为解决镍基金刚石复合电沉积过程中普遍存在镀层沉积速率慢、镀层内应力大的问题,本工作以新型高速Ni镀液为基础,考查了镀液中去应力添加剂含量、工艺参数,以及金刚石含量对镀层内应力影响的规律,并对复合镀层的微观形貌进行了表征。优选出了可以在30A/dm2的高阴极电流密度下快速电沉积低应力镍基金刚石复合镀层的镀液组成及工艺条件。结果表明：当镀液组成为十二烷基硫酸钠0.5g/L,乙酸铵3g/L,柠檬酸三钠1.5g/L,金刚石微粒浓度30g/L;施镀条件为pH值3~4,温度50℃时,制得的复合镀层内应力最低。     

电沉积Ni-P非晶纳米SiC复合镀层的工艺研究

为了提高非晶镀层的硬度,在Ni-P镀液中加入高硬度、高耐磨性的纳米微粒SiC,采用电沉积方法制备了Ni-P非晶纳米SiC复合镀层.研究了工艺温度、电流密度和镀液中SiC浓度对非晶纳米复合镀层中P含量和SiC纳米颗粒分布的影响,并用扫描电镜对镀层表面进行了观察,通过纳米显微力学探针测量了镀层硬度.结果表明:随电流密度增大和镀液中SiC含量的增加,镀层中纳米SiC的复合量增加;镀液温度在60℃时,镀层中SiC含量最大,复合镀层的硬度显著提高,可达到7.4 GPa,比普通的Ni-P非晶镀层大为提高.     

Excellent solid lubrication of electrodeposited nickel-multiwalled carbon nanotube composite films

Nickel-multiwalled carbon nanotube (MWCNT) composite films were fabricated by an electrodeposition technique, and their frictional properties were investigated by ball-on-plate type friction testing using an Al₂O₃ ball as a counter surface without lubricant. Ni-MWCNT composite films showed superior frictional properties compared to nickel films. The friction coefficient of Ni-MWCNT composite films decreased with increasing MWCNT content. The Ni-0.5 mass% MWCNT composite film showed the minimum friction coefficient value of 0.13.     

Macrodispersion of multi-walled carbon nanotubes for conductive films

Understanding of the effect of the multi-walled carbon nanotube (MWCNT) dispersion process on physical properties of MWCNT film is crucial in process optimization of MWCNT film-based products. In the present work, the electrical conduction property of MWCNT films according to various conditions in MWCNT dispersion is investigated. Spectroscopic analysis of dispersed MWCNTs show that the electrical resistance of the MWCNT conductive film is affected by an increase in the electrical contacts between adjacent CNTs due to CNT debundling and physical damage caused by ultrasonic processing. Based on the two conflicting parameters, dispersion guidelines for highly conductive MWCNT film are presented.     

Multiwalled carbon nanotube film for strain sensing

We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363?K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications.     

Enhanced thermoelectric performance of CuAlS2 by adding multi-walled carbon nanotubes

In this paper, we report the first-ever study on a relatively uniform dispersion of multi-walled carbon nanotubes (MWCNTs) in CuAlS₂ nanoparticles, synthesized by high-energy ball-milling, and study the thermoelectric properties of the bulk materials. A vortex mixer and bath sonicator are used to achieve well dispersion of nanotubes in the matrix, and then the powder is hot-pressed. Carbon nanotubes dispersed in the matrix improve electrical conductivity and Seebeck coefficient. The addition of MWCNT causes an increase in the grain boundary and facilitates phonon scattering, resulting in a reduction in the lattice thermal conductivity and finally total thermal conductivity. The optimum amount of carbon nanotubes is effective for reducing thermal conductivity and increasing electrical conductivity, thereby elevating the figure-of-merit of the nanocomposites. Finally, the figure-of-merit is highly influenced by total thermal conductivity, and the maximum figure-of-merit was obtained for CuAlS₂/0.5 wt% MWCNT composite, which indicated about 20% improvement.     

Morphological and compositional engineering of Ni/carbon nanotube composite film via a novel cyclic voltammetric route

Ni/multi-walled carbon nanotubes (MWCNTs) composite films were deposited on the glassy carbon electrode (GCE) by a Ni plating bath containing homogeneously dispersed MWCNTs using polyvinylpyrrolidone (PVP) as dispersion additive. Incorporation of MWCNTs into Ni matrix was greatly enhanced by the application of cyclic voltammetric (CV) deposition technique. The structure and nature of the Ni/MWCNT were characterized by field emission scanning electron microscope (FE-SEM) and X-ray diffraction (XRD). The results show that the content of MWCNT and the morphology of the deposited Ni/MWCNT composite film can be controlled by selecting the appropriate electroplating conditions. Further study indicates that the obtained Ni/MWCNT showed excellent electro-catalytic activity for the oxidation of ethanol in alkaline solution.     

聚吡咯／多壁碳纳米管的合成及电化学行为

在含有多壁碳纳米管(MWCNT)的十二烷基苯磺酸钠(SDBS)溶液中电化学氧化吡咯(Py)制得聚吡咯/多壁碳纳米管(PPy/MWCNT)导电复合膜。研究了聚合温度、电流密度、吡咯浓度对PPy/MWC-NT复合膜沉积量的影响,采用交流阻抗谱(EIS)法研究了该导电复合膜的电化学行为,并用扫描电子显微镜对其表面形貌进行了观察。实验结果表明,随着温度的降低、电流密度及吡咯浓度的增大,复合膜沉积量变大。与纯PPy膜相比,PPy/MWCNT复合膜有更好的电子传递行为,而复合膜表面更加粗糙、疏松。     

Comparison of dye solar cell counter electrodes based on different carbon nanostructures

Three characteristically different carbon nanomaterials were compared and analyzed as platinum-free counter electrodes for dye solar cells: 1) single-walled carbon nanotube (SWCNT) random network films on glass, 2) aligned multi-walled carbon nanotube (MWCNT) forest films on Inconel steel and quartz, and 3) pressed carbon nanoparticle composite films on indium tin oxide-polyethylene terephtalate plastic. Results from electrochemical impedance spectroscopy and electron microscopy were discussed in terms of the catalytic activity, conductivity, thickness, transparency and flexibility of the electrode films. The SWCNT films showed reasonable catalytic performance at similar series resistance compared to platinized fluorine doped tin oxide-coated glass. The MWCNTs had similar catalytic activity, but the electrochemical performance of the films was limited by their high porosity. Carbon nanoparticle films had the lowest charge transfer resistance resulting from a combination of high catalytic activity and dense packing of the material.     

Growth of spin-capable multi-walled carbon nanotubes and flexible transparent sheet films

Iron-catalyzed spin-capable multi-walled carbon nanotubes (MWCNTs) were grown on a SiO2 wafer by chemical vapor deposition, which was carried out at 780 degrees C using C2H2 and H2 gases. We fabricated a flexible transparent film using the spun MWCNTs. The MWCNT sheets were produced by being continuously pulled out from well-aligned MWCNTs grown on a substrate. The MWCNT sheet films were manufactured by simply carrying out direct coating on a flexible film or glass. The thickness of the sheet film decreased remarkably when alcohol was sprayed on the surface of the sheet. The alcohol spraying increased the transmittance and decreased the electrical resistance of the MWCNT sheet films. The sheets obtained after alcohol spraying had a resistance of -699 omega and a transmittance of 81%-85%. The MWCNT sheet films were heated by applying direct current. The transparent heaters showed a rapid thermal response and uniform distribution of temperature. In addition, we tested the field emission of the sheet films. The sheet films showed a turn-on voltage of -1.45 V/microm during field emission.     

Poly(3- hydroxybutyrate)/Bioglass(®) composite films containing carbon nanotubes

Poly(3hydroxybutyrate) (P(3HB))/Bioglass(?)?composites incorporating multiwalled carbon nanotubes (MWCNTs) have been successfully prepared by the solvent casting technique. The microstructure, electrical properties and bioactivity of the composites were characterized using scanning electron microscopy, x-ray diffraction and current-voltage measurements. Different concentrations of MWCNTs were used to determine their effect on the electrical properties of the composites. MWCNTs and Bioglass(?) particles were found to be homogeneously dispersed throughout the P(3HB) matrix. The electrical resistance of the composite samples decreased on increasing the MWCNT concentration, as expected. An in vitro degradation study in simulated body fluid (SBF) was carried out on composite samples. The formation of hydroxyapatite on the surfaces of P(3HB)/Bioglass(?)/MWCNT composite films was confirmed after two months of immersion in SBF. This hydroxyapatite layer was not formed on the neat polymeric films and on composites containing MWCNTs only (without Bioglass(?)). It was found that the presence of MWCNTs did not hinder the bioactivity of the Bioglass(?) particles, as confirmed by SEM and XRD studies on composite samples.     

Optically transparent carbon nanowire thin film

Thin films of amorphous carbon nanowire (a-CNW) have been fabricated from crossed multi-walled carbon nanotube (MWCNT) thin film. The fabrication was done by means of ion beam irradiation on various substrates. It is found that the a-CNW thin films show electrical conduction behaviour, and electrical conductivity varies after annealing. In addition, the transmission spectra in the visible range reveal that the film has above 90% optical transmission. It can be ascribed to the fact that the decreased crystallinity of MWCNTs by ion beam irradiation has caused the incremental increase of optical transmission. We also report on a method for cutting or destroying a-CNWs using low-energy focused electron beam from a scanning electron microscope.