Kinetic Model of Metallocarbohedrene Formation in Arc Plasma Generator

A kinetic model of the formation of stable metal-carbon clusters, which have been designated metallocarbohedrenes, is developed.

The metals chosen for the theoretical analysis were titanium and zirconium. An optimum starting composition of composite electrodes was found. The fullerene and Met-Car yields for different metal-to-carbon mass ratios were determined. The maximum yield of Ti₈C₁₂ was 0.4% while the maximum yield of Zr₈C₁₂ was 0.6%. The theoretical mass spectra of carbon and metallocarbon clusters were explored.     

Kinetic Model of Metallofullerene Formation in Contact Arc Generator

Abstract

A kinetic model of the metallofullerene growth process in a contact are generator is developed. the metals chosen for the kinetic analysis were lanthan and calcium. An optimum starting composition of composite electrode was found. In addition, it was discovered that small amounts of metal impurities reduced the fullerene yield just slightly.     

Kinetic Model of Metallofullerene Formation in Contact Arc Generator

A kinetic model of the metallofullerene growth process in a contact are generator is developed. the metals chosen for the kinetic analysis were lanthan and calcium. An optimum starting composition of composite electrode was found. In addition, it was discovered that small amounts of metal impurities reduced the fullerene yield just slightly.     

Kinetics of Fullerene Formation in a Contact Arc Generator

Abstract

A kinetic model of the fullerene growth process in a contact arc generator is developed. On the basis of the kinetic model, the yield of the magic fullerenes C₆₀ and C₇₀ is calculated. The fullerene yield is determined by the temperature gradient in the fullerene formation zone, the carbon vapor concentration and the helium jet velocity in the interelectrode space. We found that the upper boundary value of the magic fullerene yield was about 20%.     

Kinetics of Fullerene Formation in a Contact Arc Generator

A kinetic model of the fullerene growth process in a contact arc generator is developed. On the basis of the kinetic model, the yield of the magic fullerenes C₆₀ and C₇₀ is calculated. The fullerene yield is determined by the temperature gradient in the fullerene formation zone, the carbon vapor concentration and the helium jet velocity in the interelectrode space. We found that the upper boundary value of the magic fullerene yield was about 20%.     

Model of Improved Arc Generator for Fullerene Production

Process of fullerene formation and fragmentation is studied in various zones of fullerene generator. Fullerenes are produced utilizing carbon arc method, in which graphite electrodes are vaporized in a low pressure helium atmosphere by passing an electrical current through the electrodes. The effects of the gas pressure and intensity of the direct current on fullerene yield are investigated. Maximum fullerene yield of 8% is found in a raw soot after the evaporation of graphite by a 60 A direct current, in a helium ambient under the pressure of 8 kPa.     

Spectral Diagnostics of Helium-Carbon Arc Plasma During Carbon Nanostructure Formation

The quantitative diagnostics of carbon arc during the process of carbon nanostructure formation is presented. Temperature within 3500-5500 K and concentration within 2*10¹⁵ - 2*10¹⁶ cm^-2 of C₂(a ³II_u, v=0) were determined upon input power and plasma coordinates at arc gap 0.5 ± 0.2 mm favoring the process yield. The total carbon vapor pressure in the discharge zone was estimated as equal to 30 kPa.     

变极性等离子弧穿孔熔池受力及焊缝成形稳定性

通过YB005-01型压力变送器测定相同参数条件下正极性等离子电弧力大于反极性等离子电弧力,并建立了铝合金VPPA焊接穿孔熔池受力模型,分析了在不对称正、反极性等离子电弧力的作用下,穿孔溶池稳定性及其焊缝成形机理.同时进一步分析铝合金VPPA力学特性,掌握了焊接电流和离子气流量等重要焊接参数对其影响.经穿孔焊工艺实验,...     

等离子弧焊接熔池和小孔形成过程数值分析

目的 研究等离子弧焊接穿孔过程中熔池内部的金属流动情况和小孔动态变化过程。方法 通过“传热-熔池流动-小孔”之间的相互耦合关系,建立了等离子弧焊接穿孔过程的数值分析模型,通过VOF方法追踪了小孔界面,采用FLOW-3D软件模拟了等离子弧焊接熔池和小孔的形成过程,定量计算了等离子弧焊接温度场、熔池流场及小孔形状;分析了等离子弧焊接熔池和小孔行为;并通过等离子弧焊接实验数据验证了模拟结果。结果 当焊接时间为0~1.0 s时,小孔深度曲线与熔深曲线几乎相同,小孔底部紧贴熔池底部;在2.8 s以后,小孔深度曲线与熔深曲线有一定距离,小孔深度曲线在一定范围内波动,等离子弧焊接电弧挖掘作用到达极限,电弧压力与其他力达到平衡状态。模拟的焊缝熔深为8.04 mm、熔宽为13.20 mm,实验测得的焊缝熔深为8.00 mm、熔宽为13.42 mm。结论 构建的随小孔动态变化的曲面热源模型和电弧压力模型可以描述等离子弧焊接过程中的电弧热-力分布;模拟出了等离子弧焊接熔池和小孔动态演变过程;模拟得到的等离子弧焊接焊缝形貌与实验测得的焊缝形貌基本吻合。     

Multifunction Plasma Arc Equipment

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Kinetic Model of the Formation of Protein Crystals in Capillaries by Counterdiffusion

A kinetic model of crystallization of lysozyme is proposed, and computer calculations of this process are carried out. The conditions for the formation of such crystals are determined. Under these conditions, individual crystals were grown that were suitable for X-ray examination. The developed model enables prediction of the quantity, size, and place of crystal nucleation inside the capillary.     

Technological Capabilities of Vacuum Arc Plasma Sources

Vacuum arc plasma sources based on the self‐maintained discharge developing in the cathode material vapor enable plasmochemical synthesis of nitride and carbide compounds. Reactive gas is injected in the metal plasma flux to implement the plasmochemical synthesis of compounds. By controlling the plasma flux parameters and taking into account the ion current density distribution in the active volume, properties of the formed coating may be managed. The development of plasma technology leads to possibility of fine controlling of gas pressure and reactive gas composition, degree of plasma flux focusing, flux separation from the drop fraction. If the plasma flux is free of droplets the composition and structure of a coating can be effectively controlled by varying technological parameters.     

电弧等离子体法在纳米材料制备中的应用

电弧等离子体法可广泛用于多种纳米粉末、纳米管及纳米薄膜的制备.介绍了电弧等离子体法制备纳米材料的基本工作原理及其在制备各种纳米材料的应用,分析了电弧等离子体法的特点与优势,并展望了其发展前景.     

电弧等离子体法在纳米材料制备中的应用

电弧等离子体法可广泛用于多种纳米粉末、纳米管及纳米薄膜的制备。介绍了电弧等离子体法制备纳米材料的基本工作原理及其在制备各种纳米材料的应用，分析了电弧等离子体法的特点与优势，并展望了其发展前景。     

底喷式等离子体发生器的输出特性研究

等离子体点火是发射药燃烧的一种新型点火方式,等离子体发生器性能会影响等离子体的输出效果。为了实现发射药高效的等离子体点火作用而研究等离子体发生器的输出性能。通过调整底喷式等离子体发生器内部关键参量,分析了发生器输出特性影响规律,优化了等离子体发生器内部结构参数,并在30 mm火炮中进行了试验。结果表明:等离子体发生器效率和输出电压及等离子体射流压强随毛细管孔径增加而下降,但随放电通道长度增加而增加;增加脉冲功率源的充电电压能够提高等离子体射流动能和压强峰值;聚乙烯(PE)和聚四氟乙烯(PTFE)两种材质对等离子体发生器输出特性影响不显著;经优选后的底喷式等离子体发生器能够在火炮装置中有效地点燃发射药。     

阴极弧等离子体沉积NbN薄膜

利用磁过滤等离子体沉积装置，结合金属等离子体积技术，在Si基底上分别用动态离子束增强沉积和非增强沉积的方法来制备NbN膜，对二者予以比较，并探讨了非增强沉积过程中基底温度对NbN膜层的影响，温度升高使膜层中N的含量先呈上升趋势，随后又稍微降低，温度升高促进晶粒生长，使晶粒尺寸变大，从室温到约300℃的温度下得到的薄膜在（220）峰表现出很强的择优取向，500℃的沉积温度下，（220）峰变的很弱，（200）峰表现出择优取向，500℃时膜层中得到单一的δNbN相；表面形貌方面，温度越低，薄膜越不完整，在500℃左右才能得到光滑完整的NbN膜。与非增强沉积相比，增强沉积不需加热，在温下就能得到光滑致密的NbN膜，膜层中N的含量更高，且没有明显的择优取向。     

Jet Formation in Plasma Sprayers

Optospectroscopic studies of plasma jets in powder sprayers have been made. It has been shown that the jet of the PlasmaTechnik AG sprayer is a periodically pulsating formation similar to that generated by the twojet plasma torch. A scheme of a plasmasonic reactor for treatment and synthesis of gaseous and condensed materials is proposed.     

等离子喷枪内电弧动力学与等离子体特性的三维数值模拟

基于局域热力学平衡假设,建立三维非稳态等离子电弧的湍流模型,应用计算流体力学软件ANSYS CFX模拟了氩/氢等离子喷枪内阳极弧根的再附着过程、电弧与气流的相互作用以及等离子体温度和速度分布。结果表明,在冷气流推动下,阳极弧根向喷嘴下游移动,电弧被拉长,弧电压升高,电场强度增大。当电弧向下游移动到电场强度足够大时,电弧击穿并形成新的弧根。喷枪内电弧波动导致喷枪出口等离子体最大温度和最大速度发生波动,滞后时间为10μs。喷枪内的流动与传热具有明显的三维特征,与温度分布相比,速度分布的三维特征更明显且更向中心处集中。     

直流非转移弧等离子喷枪中电弧的工作特性研究

利用计算机数值模拟技术，采用有限容积方法，针对自制的低能耗、高效率内送粉等离子喷涂设备，对喷枪内部电弧长度及其对流体特性的影响进行了分析研究。结果表明，通过增加进气流量和减少电流的大小，均使得等离子电弧长度增加，阳极弧根位置逐渐向下游移动，但是产生这两种现象的机理以及对气流温度和速度的影响是不同的。