Degradation of gas-liquid gliding arc discharge on Acid Orange II

The effects of pH value, initial concentration of dye solution and temperature on the degradation efficiency of Acid Orange II (AO7) using gas-liquid gliding arc discharge were investigated. The influences of pH value and temperature on degradation efficiency were not apparent. Increasing initial solution concentration caused the decrease of degradation rate and the increase of absolute degradation quantity. Considering energy efficiency and absolute degradation quantity, the gas-liquid gliding arc discharge is fit for treating high concentration organic wastewater. A possible mineralization pathway was proposed through the analysis of intermediate products detected by gas chromatograph coupled with mass spectrophotometer (GC-MS) and ion chromatograph (IC). Hydroxyl radicals reacted with the azo linkage-bearing carbon of a hydroxy-substituted ring, leading to the cleavage of -C-N- and degradation of AO7. The solution biodegradability was significantly improved (BOD(5)/COD from 0.02 to 0.43). The toxicity of intermediate products was lower than that of the initial Acid Orange II.     

铝合金导电管腐蚀失效原因分析

用于高压隔离开关的铝合金导电管存在着严重而普遍的腐蚀问题,危及高压隔离开关的正常运行.运用能谱分析、金相分析和电子探针等技术对铝合金导电管的破损原因进行了分析.结果表明,导电管存在着高度定向的纵向显微组织和局部脱溶,Cu,Fe等有害元素的相在晶界处大量连续析出,造成晶界附近出现贫化区,由于导电管的工作环境为近海海洋大气带,其中含有大量的侵蚀性阴离子,众多因素是导电管的腐蚀成因.其腐蚀过程为先在表面发生点蚀,然后发展成晶间腐蚀,在晶间腐蚀和内应力的协同作用下最终开裂形成剥蚀.     

Homogeneous arc ablation behaviors of CuCr cathodes improved by chromic oxide

Cathode ablation is one of the dominant limitations for extending the maximum operating time of arc heaters.In this work,the arc ablation behaviors and mechanisms of commercial CuCr10,CuCr25,and CuCr50 cathodes were investigated for pure copper and pure chromium cathodes.The discharging homo-geneity was improved with the increase of chromium content in the cathodes,which was attributed to the formed chromic oxide layer.The CuCr50 cathodes exhibited the lowest ablation rate with a reduction of 27.0％ compared to the copper cathodes.The chromic oxide formed in the pit protected the bottom matrix,leading to a homogeneous ablation process.The mechanism for the improved homogeneous ablation behaviors of the CuCr50 cathodes was proposed and featured by the suppression of deep pits and the dispersion of arc foot.Future attention will be focused on designing composite cathodes with an anti-ablation surface layer and a good conductive matrix.     

The observation of unipolar arc damage on stainless steel and TiC coatings on stainless steel

Unipolar arcing represents a plasma-surface interaction process leading to surface damage and metal impurity influx in tokamaks. It develops if the sheath potential formed in the plasma-surface contact is high enough to ignite and sustain a micro-arc. A laser-produced plasma was used for a comparison of the arc damage produced on stainless steel surfaces with that on surfaces protected with a coating of TiC a few microns thick. Smooth coatings of superior-quality TiC were produced by the activated reactive evaporation process, which is a plasma-assisted physical vapor deposition process. For a sufficiently high electron temperature in the laser-produced plasma a large number (about 300 000 cm^?2) of unipolar arc craters were observed on the stainless steel surface which had been exposed to the expanding laser-produced plasma cloud for a few hundred nanoseconds. In comparison, no similar arc craters were detected on the surfaces protected by the TiC coating which showed minimum damage limited to the laser beam impact area.     

Scale-up analysis and development of gliding arc discharge facility for volatile organic compounds decomposition

The influences of inlet gas flow rate and reactor configuration on volatile organic compounds (VOCs) decomposition efficiency in a traditional gliding arc (T-GA) facility are studied based on laboratory experiments and numerical simulation. The ratio of the nozzle diameter and the shortest distance of two electrodes should be maintained in a suitable value range to guarantee the decomposition efficiency, which indicates simply enlarging the nozzle inner diameter is not a proper way to raise the T-GA treatment capacity in a fixed supply voltage condition. A developed gliding arc gas discharge (D-GA) reactor based on a modified gas feed system is proposed: small flow rate air goes through the bottom nozzle to process the GA evolution, and high flow rate contaminated gas goes frontal through the plasma region and decomposes. The performances of D-GA reactor in the decomposition of VOCs with relative high gas flow rate, including decomposition efficiency and specific energy consumption, are better than T-GA reactor. D-GA reactor also avoids the drawbacks of the increases of power system amount and electric power consumption in multi-electrode GA system.     

Flexible strain sensors fabricated with carbon nano-tube and carbon nano-fiber composite thin films

This paper presents the fabrication of 3 × 3 flexible strain sensor arrays using conductive polymer solutions with fillers including carbon nano-fibers and multi-walled carbon nano-tubes. The strain sensor arrays were made on polyurethane substrates using patterned surface treatment and the tilted-drop process. Atmospheric plasma was used to enhance or reduce the surface energy in specific areas for patterned surface treatment. The performance of fabricated strain sensors made using conductive polymer solutions with different ingredients was investigated. The measured gauge factors were in the 0.34 to 7.98 range for the strain of 3-7%. Under a bending test exceeding 50 times at a 150° angle, sensor damage was not observed. The demonstrated fabrication method is capable of producing conductive polymer sensors with complex designs, high reliability and is suitable for mass production.     

Arc-instability generated during the Joule heating induced crystallization of amorphous silicon films

Joule heating induced crystallization (JIC) was accomplished by applying an electric field to a conductive layer located beneath the amorphous silicon film. This study found that an intense arc is generated at the interface between the silicon and the electrode. The artificial modification of a JIC-sample structure led us to the finding that arc generation is caused by the dielectric breakdown of a SiO₂ layer that is sandwiched between the transformed polycrystalline silicon and a conductive layer at high temperatures during Joule heating.     

含表面缺口层压板的损伤形貌特征

本文用改进的揭层技术研究含表面缺口层压板的损伤形貌特征.试验了两种即矩形和圆弧形剖面的表面缺口试样.结果表明,改进的揭层技术可以清楚地显示出层压板各层的损伤形貌,因此也给出了含表面缺口层压板损伤形貌特征的一些有意义的结果.     

Decolorization of Acid Orange 7 solution by gas-liquid gliding arc discharge plasma

The decolorization of 180 microM aqueous solutions of Acid Orange 7 (AO7) by means of a non-thermal plasma technique (i.e., the gas-liquid gliding arc discharge, which is generated between at least two metal electrodes with AC high voltage) was investigated in this paper. The effects of the plasma treatment time and the type of feeding gas, including air, oxygen, nitrogen and argon of the dye removal were determined. It is found that the voltage cycles of the gas-liquid gliding arc discharge are characterized by a moderate increase in the tension which is represented by a peak followed by an abrupt decrease and a current peak in the half period (10 ms); the concentration of AO7 solution decreases exponentially to reach 58.9, 77.4, 89.1, 95.1 and 99% in 25, 50, 75, 100 and 125 min, respectively, and the ln(Ct/C0) varies linearly with the treatment time t, indicating that decolorization reaction follow first pseudo-order kinetics with a constant rate of 0.03327 min(-1) when air was used as feeding gas; the decolorization rate during the plasma treatment is the greatest for oxygen as the feeding gas, in turn followed by air and argon, and was the least when using nitrogen. The variations of pH and conductivity and the formations of hydrogen peroxide and ozone are measured.     

Effect of hybrid woven fabrics structure on their electrical properties

The aim of this study is to investigate the influence of hybrid textile woven fabric structure on the electrical resistivity. Weave structure was varied by varying the weave pattern and the conductive yarn density in the woven fabrics. Electrical surface and volume resistivity were measured and compared to the fabric structural properties. Results showed that not only the conductive yarns percentage has an important effect on the electrical resistivity but also the weave structure. The most influencing structural parameter on surface resistivity was the woven fabric surface profile as it controls the contact quality between the conductive yarns and the measuring electrodes. A high surface resistivity was noticed when the contact quality was poor. When this contact quality was good, a linear correlation was found between surface electrical resistivity and the cover firmness factor, the apparent conductive fiber surface area as well as the conductive yarn floating length of the woven structures.     

Synthesis of graphene flakes using a non-thermal plasma based on magnetically stabilized gliding arc discharge

Abstract

The use of non-thermal plasma at atmospheric pressure has emerged as a technique for the substrate-free, gas-phase synthesis of graphene nanoflakes (GNFs). In this paper, a non-thermal plasma based on magnetically stabilized gliding arc discharge (MSGAD) was employed to prepare GNFs. The effects of the carbon-containing precursor, plasma gas, and arc current on the GNFs synthesis were investigated. The technique produced GNFs with sizes of 50–200?nm and 1–20 layers, spherical carbon nanoparticles with 10–40?nm diameters, and graphitic particles. The results showed that the formation of GNFs depended on the selection of proper process parameters, such as precursors with a high H/C ratio, an Ar-N₂ plasma gas, a low arc current, a low precursor flow rate, and a suitable plasma gas flow rate. Correlations between the process parameters and the product morphology indicated that abundant H atoms and fewer polycyclic aromatic hydrocarbons were favorable for the formation of GNFs.     

铜钛硅碳石墨合金材料摩擦磨损性能研究

为研究铜钛硅碳石墨合金材料摩擦磨损性能,通过常规的粉末冶金方法制备了铜钛硅碳石墨材料。对样品硬度等性能的测试,选择出87%Cu的最优配方。再用无流磨损和载流磨损实验测试其摩擦磨损性能,进而通过扫描电镜对磨损表面进行观察,探讨摩擦磨损机理。结果表明,无流磨损过程中,磨损量呈线性增长,磨损的主要形式为梨削;载流磨损过程中,磨损量呈非线性增长,随着行程的增加,磨损率降低,磨损的主要形式有梨削和电弧烧损,磨损率降低可能是杂质Al相弥散强化铜基体所致,其微观机理是一个复杂的各种机理的组合。     

Facile and rapid fabrication of conductive layers on flexible polymer surfaces and their application to flexible strain sensors

The advantage of building a conductive network on the surface layer of a flexible substrate is that it has less impact on the elastic recovery properties of the substrate, which is particularly important for flexible strain sensors. However, the facile construction of robust conductive layers on the surface of flexible polymers remains a challenge. Herein, a method for constructing robust conductive layers on the surface of thermoplastic polymers was developed by immersing thermoplastic polymers in a solvent/conductive filler dispersion with the assistance of ultrasound. The solubility of the solvent in the flexible polymer and ultrasonic field are key to the preparation of the conductive layer. This method has the advantages of fast preparation and robustness of the conductive layer and can be applied to thermoplastic polymers of different polarities as well as different types of conductive fillers. Based on this method, a flexible strain sensor with a robust carbon black conductive layer on the styrene–butadiene–styrene block copolymer was prepared in as short as 2 s. The advantages of a broad strain detection range (0.1% to 400%) and robust cyclability of the sensors were exhibited. The sensors can be used for human motion monitoring as well as solvent detection.

     

电弧放电法制备石墨烯及其在导电油墨中的应用

导电油墨是印刷电子技术中使用的关键电子材料, 而导电填料作为导电油墨的主要成分要求其化学性能稳定且电导率高。其中, 基于石墨烯的导电油墨因为其、透射电子显微镜、拉曼光谱等手段对制备的石墨烯进行了表征。结果表明: 直流电弧放电法制备的石墨烯为2~10层、尺寸在100~200 nm范围且纯度高、结晶性好。在此基础上, 研究了涂层厚度、热处理温度以及弯曲角度等对石墨烯导电油墨导电性能的影响。研究发现, 石墨烯导电油墨电阻率与涂层厚度、热处理温度成反比, 且随着厚度、温度的增加石墨烯导电油墨的电阻率逐渐降低。并且样品在柔性基底上经过不同角度的弯曲折叠后电阻率没有明显变化。当厚度为170 μm的样品经过360℃ (30 min) 热处理后, 石墨烯导电油墨的电阻率仅为0.003 Ω·cm。上述结果表明, 电弧法制备的石墨烯导电油墨有望成为未来印制电子领域的关键材料。     

Leakage Current Analysis of Nitride-Based Photodetectors by Emission Microscopy Inspection

Leakage properties of nitride-based photodetectors (PDs) subjected to inductively coupled plasma (ICP) etching has been investigated by using emission microscopy inspection (EMMI). ICP etching would cause significant damage to GaN metal-semiconductor-metal (MSM) PDs. The damage was proven to induce leakage current via the conductive surface of the device by using emission microscopy inspection. However, the surface damage of MSM PDs could be partially recovered by E-beam SiO₂ passivation. As for the passivation for p-i-n photodetectors, the effect was not significant in the reduction of dark current due to smaller etched area as compared to the whole area of p-i-n PDs. The leakage current path analysis of p-i-n PDs by EMMI technique had also been investigated. Finally, the plasma enhanced chemical vapor deposition (PECVD) SiO₂ passivation was proven to be a potential process to improve the reliability of p-i-n PDs.     

电应力对HfO2栅介质漏电流的影响

使用导电原子力显微镜（Conductive Atomic Force Microscopy,CAFM）对电压应力作用下HfO2栅介质薄膜局域漏电点的形成和产生机制进行了研究,结果表明,在电压应力作用下,HfO2介质层中的缺陷被驱动和聚集形成导电通道,产生漏电点。漏电点产生的数量、漏电流大小均受电压应力和作用时间的影响。HfO2栅介质层中晶界处的缺陷密度高于晶粒处,导致晶界处更容易产生漏电通道。在栅介质击穿过程中,电压应力在诱发漏电流产生的同时产生焦耳热,对HfO2介质表面造成热损伤,导致击穿后HfO2介质表面出现凹陷。     

Heat loss in the channel of a plasmatron

A mathematical model is constructed and a computational experiment is carried out to determine the characteristics of a longitudinally blown electric arc in the channel of a plasmatron under conditions of local thermal equilibrium. A feature of the model is that it makes allowance for radiation transfer in the real spectrum of an electric- arc plasma. An algorithm for solving the problem is presented and the effect of radiation reabsorption on the radiation and conductive heat loss in the plasmatron channel is shown.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 3, pp. 505–511, March, 1990.     

Enhanced crack detection sensitivity of carbon fiber composites by carbon nanotubes directly grown on carbon fibers

The ability of highly conductive hybrid carbon–fiber/carbon nanotube loaded epoxy composites to sense matrix cracking damage in situ is demonstrated. Multi-walled carbon-nanotubes (MWCNTs) are grown perpendicular to and on the surface of a woven carbon–fiber fabric using a chemical vapor deposition process. An increase in sensitivity of resistance change under interlaminar fracture is shown through a series of double cantilever beam (DCB) tests on samples prepared with MWCNTs grown on both sides of carbon–fiber fabric lamina placed at the top and bottom surfaces of an 8-layer test panel whereas samples with MWCNTs inside the samples did not show much increase in sensitivity of resistance change compared with the baseline samples without MWCNTs. The results suggest that the addition of surface positioned hierarchical carbon-nanotube lamina on composite structures has the potential for autonomic sensing of internal matrix damage.     

表面温度动态校准中导热平板对时间常数测试影响分析

针对阶跃变化表面温度装置中的表面温度传感器的数学模型进行了建模,分析了导热平板对被测表面温度传感器时间常数的影响,通过对不同时间常数的表面温度传感器进行数值仿真计算,得出当被测表面温度传感器时间常数大于20倍导热平板时间常数时,导热平板对被测表面温度传感器时间常数的影响可以忽略。     

银纳米线-聚对苯二甲酸乙二醇酯透明导电胶膜

以银纳米线作为导电填料,以聚对苯二甲酸乙二醇酯(PET)为柔性衬底,采用平板热压机通过热压方式制备了银纳米线-PET透明导电胶膜。研究了银纳米线-PET导电胶膜的耐弯曲性能、电学性能以及透光性。结果表明,所制备的银纳米线-PET导电胶膜透光率达到80%以上,表面电阻率达到1×10^-3Ω·cm。银纳米线-PET导电胶膜经过500次的弯曲循环后电阻率未下降。随着银纳米线溶液浓度的增加,银纳米线-PET导电胶膜透光性下降,表面电阻率增加。