直流激励的大气压氩气喷枪的光谱研究

利用正高压驱动空心针-板喷枪装置,通入工作气体氩气,在大气压空气中产生了均匀稳定的喇叭状等离子体羽。电学和光学测量结果表明,放电虽然是在直流电源驱动下工作,但放电为周期性的脉冲。通过对等离子体羽发光信号进行空间分辨测量,研究了脉冲的形成机理,发现除针尖附近的电晕放电外,等离子体羽是以正流光(等离子体子弹)从针尖向着接地电极方向传播的。采用光谱学方法,对电子激发温度随电压的变化及其空间分布进行了测量。结果表明,电子激发温度(约为3 eV)随电压的增大而升高,在一定电压下,电子激发温度沿气流方向也在升高。     

Mechanical and Flame Retardant Properties and Microstructure of Expandable Graphite/Silicone Rubber Composites

Flame-retardant expandable graphite (EG)/silicone rubber (SR) composites were prepared using nano-CaCO₃ particles as reinforcement filler. In addition to mechanical measurements, limited oxygen index (LOI), UL-94 and cone calorimeter tests (CCT), the thermal properties were tested by thermogravimetric analysis (TGA). The results showed that the content and particle size of the EG both had large effects on the flammability and mechanical properties of the EG/SR blends. The composites that contained 25 phr EG (50–80 mu) had excellent LOI values, 47–48, and achieved the UL-94 V-0 level while the pure SR sample had the LOI value of 25 and achieved the UL-94 V-2 level. The data obtained from the CCT indicated that the addition of EG decreased remarkably the heat release rate, smoke emission, and mass loss rate of the composites. SEM microphotographs of the EG/SR composites before and after combustion demonstrated that EG underwent a large volume expansion, and the multiporous char structure blocked heat transfer and protected the substrate from fire.     

Graphite–boron composite heater in a Kawai-type apparatus: the inhibitory effect of boron oxide and countermeasures

We have investigated the performance of a graphite–boron composite (GBC) with 3?wt % boron as a precursor for a boron-doped diamond heater in a Kawai-type apparatus at 15?GPa. We first tested a machinable cylinder of GBC sintered at 1000°C in Ar/H₂ gas (99:1 molar ratio). Boron oxide (B₂O₃) formed during sintering frequently hindered the GBC heater from stable operation at temperatures higher than 1400°C by producing melt throughout the heater together with oxide and/or silicates. We then rinsed the GBC heater in hydrochloric acid to remove B₂O₃. After rinsing, we succeeded in stably generating temperatures higher than 2000°C. We also improved a molding process of different-sized GBC tubes for convenient use and tested the molded GBC heater. It was free from the B₂O₃ problem. The electromotive force of the W/Re thermocouple was successfully monitored up to 2400°C.     

沉积铁钝化膜的傅立叶变换表面增强拉曼光谱

利用恒电流沉积技术、傅立叶变换表面增强拉曼散射技术现场研究了0 1mol/LNaOH溶液中铁金属电极在不同电位下的表面氧化物的组成。结果表明,在电极预钝化区,表面首先生成的Fe(OH)2可由拉曼谱图中出现的550cm-1表征,证实了以往的研究结果。进入钝化区,表面二价氧化物逐步转化为高价氧化物Fe3O4及α 、δ 和γ FeOOH。在电位回扫的过程中,各氧化产物的还原以及铁表面SERS活性的逐渐消失导致谱峰强度降低。     

金刚石膜的厚度及背表面过渡层对热导率的影响

 采用微波等离子体化学气相沉积（MWPCVD）方法制备金刚石膜，研究了金刚石膜的厚度以及生长初期的SiC过渡层对其热导率的影响，给出了膜厚和背表面SiC过渡层减薄厚度与金刚石膜热导率的关系。     

等离子体电极棚电光开关实验研究

 设计建造了以辉光放电形成的等离子体作电极，通光口径为80mm×80mm的普克尔盒实验，实验检测了它的开关性能。阐述了普克尔盒的结构，辉光放电等离子体电极的形成，开关驱动脉冲的产生及输出特性，电光开关的开关效率和开关速度的检测方法，给出了典型的实验结果。     

常见场致发射阴极材料的发射特性

利用三阴极加速器平台,对不锈钢、黄铜、铝、天鹅绒和石墨等几种常见场致发射材料的电流发射能力、相对启动延迟时间及其抖动进行了实验研究。实验结果表明：在二极管电压近似恒定时,不锈钢阴极启动时间延迟抖动小于8 ns,天鹅绒阴极及石墨阴极启动时间延迟抖动小于4 ns;且材料在阴极频繁工作时启动时间加快;常见金属材料中不锈钢阴极的综合性能较好;非金属材料中,天鹅绒阴极的发射能力最强,且发射延迟时间最短,但考虑到天鹅绒材料严重的出气问题,非金属材料中以石墨阴极的性能为优。     

压电波形对喷墨打印电极的调控规律

压电喷墨打印是制备印刷电子器件的主要手段之一,其墨滴喷射状态直接受压电波形的影响,因而压电波形对于器件打印具有重要意义。本文主要研究了压电波形对薄膜晶体管(TFT)电极打印效果的影响,实验通过改变压电波形的加压速率和脉冲持续时间,打印得到了一系列的电极样品,并对其图形效果及表面粗糙度进行了测量。实验表明,随着加压速率和脉冲持续时间的增大,墨滴喷出动能增大,最终打印的图形效果先改善后恶化,表面粗糙度则随之增大。在加压速率取值为0.08~1.65 V/μs、脉冲持续时间取值为1.216~2.688μs的区间内得到了失真程度较小的电极图形,在加压速率及脉冲持续时间分别为0.25 V/μs、2.688μs及0.65 V/μs、1.600μs时,电极图形化效果较好,表面粗糙度分别为59.04 nm和59.27 nm。通过对压电波形参数的合理设置,能够实现对打印图形效果的优化。     

Preparation,characterization, and performance study of beeswax/expanded graphite composite as thermal storage material

In this study, beeswax as a new energy storage material and its composite with expanded graphite were prepared and characterized for their surface and thermal properties. Surface characterization showed no chemical interaction between beeswax and expanded graphite. The thermal conductivity of the composite was improved with 117% enhancement. The thermal performance of beeswax and its composite as a heat storage material was studied in a rectangular shell-and-tube thermal storage unit. The melting point of the composite remained almost same as that of beeswax; however, the melting time was reduced considerably, from 540 to 360 min with inlet water at 80°C and a 2-lpm flow rate.     

Effect of cylinder electrode arrangement on the ionic wind properties of needle–cylinder electrodes

Needle–cylinder electrodes designed to generate ionic wind have been explored experimentally. The increase of the gap distance between needle and cylinder from 4 mm to 16 mm cause an increase of the ionic wind velocity from 1.1 m/s to 2.46 m/s. The opposite behavior was observed when this distance lengthened from 18 to 28 mm. At the same time, a step voltage was used to increase the ionic wind velocity up to 3.6 m/s. These results indicate that electrode arrangement is very important to maximize the ionic wind velocity.