低温等离子体降解偏二甲肼废水研究

该文研究了悬浮电极介质阻挡放电装置(FE-DBD)产生的低温等离子体对偏二甲肼废水的降 解效果,并对处理条件进行优化。首先,对比了低温等离子体装置、氙灯和紫外灯降解偏二甲肼废水的效果;然后,考察了低温等离子体装置的放电间隙、初始溶液 pH、工作时间和氢氧化钠加投量对偏 二甲肼降解的影响;最后,探究了低温等离子体对偏二甲肼废水 pH 值的影响。实验结果表明,不加入其他试剂的情况下,低温等离子体装置降解偏二甲肼效果好于氙灯及紫外灯;装置放电间隙从 4 mm缩短至 2 mm,偏二甲肼降解率增加 47.2%。随着等离子体处理时间的增加,偏二甲肼的含量降低,处理 20 min 即可降解 82.1% 偏二甲肼。同时,低温等离子体处理会引起偏二甲肼废水 pH 值下降,处理10 min 后废水 pH 从 10 下降至 6.9。废水初始 pH 在 2～10 时,偏二甲肼降解率随废水 pH 值的升高而增大 ：与 pH＝2 相比,初始 pH＝10 时偏二甲肼降解率增加 65.9%。低温等离子体处理 10 min 后,往废水中加入氢氧化钠溶液至终浓度为 1 mg/mL,再继续处理 10 min,可将偏二甲肼降解率提高至 95%。     

低温等离子体制备天然功能性多糖

天然多糖由于具有天然可再生、价格低廉、生物相容好等优点,受到广泛关注。该文选择具 有代表性的羧甲基纤维素钠和海藻酸钠作为研究对象,探讨了低温等离子体技术应用于多糖改性的可 行性。通过系统地研究等离子体处理对这两种多糖溶液黏度、pH 值、菌落总数及 1,1-二苯基-2-三硝 基苯肼清除率等性能的影响,并在此基础上,分析等离子体处理对两种多糖结构和性质的影响差异及 相关机制。实验结果表明,处理后的多糖具备了一定的抗菌及抗氧化性能。主要机制为：等离子体处 理过程中产生的能量,使多糖内部的分子键断裂;这个过程中,也引入了含氧、含氮等活性官能团, 与断键之后的多糖稳定结合,从而赋予其相应的功能。相较于传统的酸、碱和酶提取法制备功能性多 糖,低温等离子体更为稳定、高效且没有任何化学试剂污染。因此,低温等离子体处理为功能性多糖 的制备提供了新的方法。     

应用静电纺丝法制备PZT纳米纤维薄膜

提出应用静电纺丝法制备PZT纳米纤维薄膜。研究中配制PZT溶液后再进行静电纺丝,获得了PZT纳米纤维薄膜,并且通过调整纺丝时间和沉积次数来控制纳米纤维薄膜的厚度。运用SEM对获得的热处理前后的薄膜进行了观察对比,测量其平均直径约为200 nm;运用XRD对退火后的样品进行分析,测得样品的主要成分为Pb(Zr0.52Ti0.48)O3,证明所制备的正是PZT薄膜;运用AFM测得薄膜的表面粗糙度为1.034 nm,说明该纳米薄膜材料非常的均匀整齐。     

常压氩气等离子体对碳纤维表面亲水改性研究

该文采用常压氩气等离子体对水溶液中的碳纤维进行表面改性处理,以去除碳纤维表面浆 料,并实现碳纤维的亲水功能化改性。通过扫描电子显微镜、红外光谱、X 射线光电子能谱、水静态 接触角测试及力学性能测试对改性后的碳纤维进行研究分析。结果表明,等离子体改性处理既可以去 除纤维表面的浆料和杂质污染物,保持纤维原有的凹凸沟槽形貌特征,又可以引入大量含氧极性基 团。进一步分析表明,等离子体改性处理 120 s 可以使纤维获得最优的浸润性能,水静态接触角可以 降至 45.1°。力学性能测试结果表明,这种等离子体改性方法对纤维的力学性能几乎没有影响,处理 300 s 后仍可保持碳纤维的抗拉强度在 3.23 GPa。     

光纤表面粗糙度传感器的改进

噪声光源、测量距离、表面粗糙度等主要参数都极大地影响了光纤粗糙度传感器的测量精度,为此提出了采用延时发生器和取样保持放大器来减小噪声源影响的改进表面粗糙度光纤传感器,得出最佳采样时间间隔为0.6514s,最后通过Origin的曲线拟合求出近似方程,由方程得到粗糙度参数R_z.     

钼掺杂降低TiO2氧敏薄膜最佳工作温度研究

用直流反应磁控溅射法在陶瓷基片上制备出TiO2薄膜.并进行1100℃,2h的退火处理.配置钼酸铵溶液,利用浸渍法处理TiO2薄膜若干时间.取出后,进行500℃,3h退火处理.用气敏测试箱对制备出的TiO2薄膜的氧敏特性进行试验测试,发现对氧气有很好的敏感特性,比未经此项工艺处理的TiO2薄膜的最佳工作温度降低100℃,为300℃左右,并进行SEM测试,分析其表面结构,研究气敏机理.     

化学沉积薄膜的矫顽力的控制和粘结性的改进

为了在非导体或非催化的表面化学沉积钴及其它金属薄膜,需将被镀表面活化、敏化。非导体、非金属的表面,如塑料的活化、敏化通常分两步进行:1.先将表面浸入SnCl_2溶液中使之活化,2.然后浸入PdCl_2溶液中使之敏化。     

Pyrex玻璃的ICP刻蚀技术研究

以SF6/Ar为刻蚀气体,采用感应耦合等离子体(ICP)刻蚀Pyrex玻璃,研究气体流量、射频功率对刻蚀速率及刻蚀面粗糙度的影响.采用正交实验方法找出优化的实验参数,得到Pyrex玻璃刻蚀速率为106.8 nm/min,表面粗糙度为Ra=5.483 nm,实验发现增加自偏压是提高刻蚀速率、减小刻蚀面粗糙度的有效方法.     

基于低温等离子体的流动控制数值仿真研究

对于空气的流动控制问题,由于飞机在飞行中阻力较大,采用表面放电低温等离子体是较为有效的控制方法.采用格子玻尔兹曼模型对连续放置的两组等离子体发生器对边界层流动控制进行数值仿真.得到了壁面附近空气的速度分布.将等离子体发生器布置于NACA0015翼型表面,通过藕合计算得到的驱动速度,得到了等离子体作用前后翼型表面的流场分布以及升力系数、阻力系数曲线.数值仿真结果与实验结果较为吻合,等离子体可以有效的对翼型表面边界层进行控制,增加升力,降低阻力.     

复合表面处理对CPU散热器性能的影响

研究了复合表面处理对铝合金CPU散热器性能的影响,首先通过化学氧化工艺在散热器表面制得了较丰富的微观形貌,以增大其粗糙度,之后采用冷喷涂技术,在散热器表面涂覆一层均匀的红外辐射散热降温涂料,并在风洞中测试了其性能。实验结果表面：复合表面处理后,散热片表面温度降低约4℃。     

Si基Cu/NiFe薄膜的生长及其粘附特性研究

微机械(MEMS)工艺和集成电路(IC)工艺中,在硅(Si)片上电铸高深宽比坡莫(NiFe)合金材料常出现脱落现象.提出了一种电铸NiFe合金材料的新方法,这种方法制作的合金薄膜厚度达200 μm时不脱落.此方法即对等离子刻蚀后的硅片溅射种子层铜(Cu),然后对种子层进行电镀,当其厚度达到约15 μm时,再进行NiFe合金的电铸.本文用扫描电镜、x射线衍射仪和剥离实验研究了薄膜粘附特性.研究结果表明当对种子层电镀后,随着Cu种子层厚度的增加,Cu/NiFe薄膜与基体的粘附强度增加,而薄膜的残余应力降低;同时Cu膜表面粗糙度增加,也增加了NiFe膜与Cu膜的粘附强度.     

Effect of pulse frequency on the morphology and nanoindentation property of electroplated nickel films

This paper reports the effect of pulse current with different frequencies on the morphology and mechanical properties of nickel (Ni) films deposited by electroplating. The pulse frequency varies from 0 (DC) to 500 Hz while the duty cycle (T _on/T _off) is 1 during electroplating. The average roughness and deposition rate of Ni films decrease with the increasing frequency. The smoothest Ni surface with average roughness of 16.5 nm is achieved at the frequency of 500 Hz while the deposition rate reaches a nearly stable rate of 0.04 μm/min. The surface concentration of ions does not vary with time at a sufficiently high frequency with a long off time for ion to diffuse onto the surface. It will result in much more nuclei formed on the surface of cathode at a limited growth rate to get small grains for smooth morphology. The nanohardness of Ni film initially decreases rapidly from 3.9 to 1.18 GPa at 0 to 10 Hz, respectively, then increases to about 4.87 GPa in the range of 100–200 Hz, and decreases slowly to 4.0 GPa at 500 Hz. The stiffness of Ni films electroplated by pulse current at 100–200 Hz is higher than that by dc electroplating. The compromised Ni film with smooth morphology, good hardness and proper deposition rate is obtained at frequency of 100–200 Hz under the current density of 3 Adm⁻².     

Research on corrosion resistance of metal films sputtered by rotating target and planar target

The corrosion resistance of MoNb/AlNd/MoNb film during different sputter conditions was studied for G6 rotating target sputter equipment. The results show that with the increase of sputter power and the increase of the thickness, top MoNb tends to form coarse columnar crystals, and the corrosion resistance of the metal thin films, at first, increases and then decreases with the increase of sputter power and metal thickness. As the sputter temperature increases, top MoNb tends to form coarse grains while the corrosion resistance of the film is poor. The result also release that with the increase of the target speed, top MoNb film becomes loose so that it is difficult to play a protective role because of its poor corrosion resistance ability. Under the same conditions, the sputter of the planar target film is denser; as a result, the top MoNb layer can protect the inner AlNd layer from corrosion.     

Fabrication and characterization of polyaniline-based gas sensor by ultra-thin film technology

Pure polyaniline (PAN) film, polyaniline and acetic acid (AA) mixed film, as well as PAN and polystyrenesulfonic acid (PSSA) composite film with various number of layers were prepared by Langmuir–Blodgett (LB) and self-assembly (SA) techniques. These ultra-thin films were characterized by ultraviolet–visible (UV–VIS) spectroscopy and ellipsometry. It is found that the thickness of PAN-based ultra-thin films increases linearly with the increase of the number of film layers. The gas-sensitivity of these ultra-thin films with various layers to NO₂ was studied. It is found that pure polyaniline films prepared by LB technique had good sensitivity to NO₂, while SA films exhibited faster recovery property. The response time to NO₂ and the relative change of resistance of ultra-thin films increased with the increase of the number of film layers. The response time of three-layer PAN film prepared by LB technique to 20 ppm NO₂ was about 10 s, two-layer SA film was about 8 s. The mechanism of sensitivity to NO₂ of PAN-based ultra-thin films was also discussed.     

Micro-tribological interface model for friction-induced cold start-up running dynamics

The robustness and noise warranty costs of many automotive friction materials like transmission belts or brake pad are directly affected by the frictional properties in cold start-up running. This paper presents a friction model for start-up running under cold conditions. The absorbed water, phase changes and variable lubrication regimes in cold start-up running are taken into account. The model includes the breakage of ice adhesion, ice–ice friction between the ice films on friction pairs, melting water-mediated mixed lubrication and boundary lubrication, friction elevation due to capillary adhesive effect, as well as dry contact in the end of cold start-up running. Thermal analysis is applied in conjunction with the friction model to estimate the parameters in phase transitions. A meniscus model is also integrated into the friction model to address the friction elevation due to the variation of water film thickness. It is illustrated that if the thickness of surface ice film is larger than a critical value, the static friction coefficient could be close to 1; if the thickness of melting water film is higher than the average roughness of the surface, static friction could increase due to capillary effect, and kinetic friction could decrease due to mixed lubrication resulting in wide modulation of friction during intermittent start-up transitions. This paper also presents the application of the model to elucidate the friction mechanisms in cold brake noise where the cold wet coefficient of friction (cof) could be substantially higher than the dry cof. The effects of temperature, roughness and load on cof are also characterized.     

Structural and water diffusion of poly(acryl amide)/poly(vinyl alcohol) blend films: Experiment and molecular dynamics simulations

To study the effects of composition ratios and temperature on the diffusion of water molecules in PVA/PAM blend films, five simulation models of PVA/PAM with ten water molecules at different composition ratios (4/0, 3/1, 2/2, 1/3, 0/4) were constructed and simulated by using a molecular dynamics (MD) simulation. The diffusion behavior of water molecules in blends were investigated from the aspects of the diffusion coefficient, free volume, pair correlation function (PCF) and trajectories of water molecules, respectively. And the hydrophilicity of blend composite was studied based on the contact angle and equilibrium water content (EWC) of the blend films. The simulation results show that the diffusion coefficient of water molecules and fractional free volume (FFV) of blend membranes increase with the addition of PAM, and a higher temperature can also improve the diffusion of water molecules. Additionally, the analysis of PCFs reveals the main reason why the diffusion coefficient of water in blend system increases with the addition of PAM. The measurement results of contact angle and EWC of blend films indicate that the hydrophilicity of blend films decreases with the addition of PAM, but the EWC of blends increases with the addition of PAM.     

转速对内燃机滑动轴承润滑性能的影响

该文主要分析了转速对轴承润滑性能影响的机理,并应用Ricardo轴承设计软件针对某柴油机连杆大头轴承的最大油膜压力、最小油膜厚度以及功率损耗等润滑性能进行了仿真计算,结果表明转速增加将较大地增加轴承功率损耗,但最小油膜厚度呈现先增后减,最大油膜压力呈现先减后增的趋势,而在一个循环内,最小油膜厚度持续时间延长,最大油膜压力多次出现,均加剧了轴承的疲劳.显示在高转速下惯性负荷对轴承润滑性能起主要作用.该文的结果对于高速柴油机设计具有一定的指导意义.     

高稳定薄膜电阻技术及其应用

首先对有关薄膜电阻的理论作了一定的探讨,得出薄膜电阻随电阻率的增加,其温度系数将会减小;在一定厚度范围内薄膜厚度减小,其温度系数减小;适当的成膜工艺能控制和改善电阻的温度系数的结论。给出了制备薄膜电阻的试验方法(调整薄膜的淀积条件以获得高质量的薄膜,再通过热处理激活)及试验结果,对影响电阻特性及稳定性的一些条件进行了讨论,并探讨了高稳定薄膜电阻技术在集成电路中的应用前景。该工艺现已在双极和MOS电路中得到了很好的应用,拥有更快、更好的发展前景。     

Effects of aperture size and pressure on XeF2 etching of silicon

 We developed a XeF₂ pulse etching system and clarified the Si etching characteristics. Dependencies of Si etching rates and etched roughness on the crystallographic orientation, number of pulses, pulse duration time, aperture size and etching pressure were measured. An etching depth and an etched roughness were 12.9 μm and 115 nm, respectively under charge pressure of 390 Pa, a pulse number of 10 and pulse duration time of 60 s. The etching depth increased by 36% with increasing the aperture width from 25 to 175 μm. This aperture size effect decreased from 36 to 20% with decreasing charge pressure from 390 to 65 Pa. The etched roughness decreases also with decreasing the etching pressure. The roughness was 25 nm under the charge pressure of 65 Pa, 50 pulses, 60 s. Received: 3 August 2001/Accepted: 29 October 2001