Grain Size and Photocatalytic Activity of Nanometer TiO_2 Thin Films Prepared by the Sol-gel Method

Transparent anatase TiO2 nanometer thin films with photocatalytic activity were prepared via the sol-gel method on soda-lime glass. The thickness , crystalline phase, grain size, surface hydroxyl amount and so on were characterized by scanning electron microscopy (SEM) , X-ray diffraction (XRD), transmission electron microscopy ( TEM), X-ray photoelectron spectroscopy (XPS) and UV-visible spectrophotometer ( UV-VIS). The photocatalytic activity of TiO2 thin films was evaluated for the photocatalytic decolorization of aqueous methyl orange . The effects of film thickness on the crystalline phase, grain size, transmittance and photocatalytic activity of nanometer Ti02 thin films were discussed.

Thickness dependence of grain size and surface roughness for dc magnetron sputtered Au films

The grain size and surface morphology of sputtered Au films are studied by x-ray diffraction and atomic force microscope. For as-deposited samples the grain growth mechanism is consistent with the two-dimensional （2D） theory, which gives relatively low diffusion coefficient during deposition. Annealing process demonstrates the secondary grain growth mechanism in which the thickness dependence of grain boundary energy plays a key role. The surface roughness increases with the increase of grain size.

Influences of grain size and microstructure on optical properties of microcrystalline diamond films

Microcrystalline diamond(MCD)films with different grain sizes ranging from 160 nm to 2200 nm are prepared by using a hot filament chemical vapor deposition(HFCVD)system,and the influences of grain size and structural features on optical properties are investigated.The results show that the film with grain size in a range of 160 nm–310 nm exhibits a higher refractive index in a range of(2.77–2.92).With grain size increasing to 620±300 nm,the refractive index shows a value between 2.39 and 2.47,approaching to that of natural diamond(2.37–2.55),and a lower extinction coefficient value between 0.08 and 0.77.When the grain size increases to 2200 nm,the value of refractive index increases to a value between 2.66 and 2.81,and the extinction coefficient increases to a value in a range of 0.22–1.28.Visible Raman spectroscopy measurements show that all samples have distinct diamond peaks located in a range of 1331 cm-1–1333 cm-1,the content of diamond phase increases gradually as grain size increases,and the amount of trans-polyacetylene(TPA)content decreases.Meanwhile,the sp2 carbon clusters content and its full-width-at-half-maximum(FWHM)value are significantly reduced in MCD film with a grain size of 620 nm,which is beneficial to the improvement of the optical properties of the films.

Effect of Wafer Size on the Film Internal Stress Measurement by Wafer Curvature Method

Wafer curvature method has been applied to determine the internal stress in the films using Stoney＇s equation.During the film deposition,the wafer fixation on the sample holder will restrict the deformation of the rectangle-shaped wafer,which may result in the stress datum difference along length and width direction.In this paper,the effect of wafer size and the wafer fixation on the TiN film internal stress measured by wafer curvature method was discussed.The rectangle-shaped wafers with different length/width ratios（L/W=1：1,2：1,3：1 and 4：1） were fixed as a cantilever beam.After the TiN films deposition,the profiles of the film/wafer were measured using a stylus profilometer and then the internal stress was calculated using the Stoney equation in the film.The results showed that the fixed end of the wafers limited to some degree the curvature of the wafers along the width direction.For film internal stress measured by wafer curvature method,the wafer profile should be scanned along the length direction and the scan distance should be greater than or equal to half of wafer length.When the length/width ratio of the wafer reached 3：1,the wafer curvature and the calculated stress were basically the same at different positions along the length direction.For film internal stress measured by wafer curvature method,it was recommended that the length/width ratio of wafer should be considered to be greater than or equal to 3：1,and the deformed profile was scanned along the length direction.

EFFECT OF PARTICLE SIZE ON THE FILMING PROCESS OF POLYSTYRENE LATEX STUDIED BY AFM

The film formation process of micro-PS particles (diameter 742 nm) and nano-PS particles (diameter 29 nm) was studied by atomic force microscopy and differential scanning calorimetry. During a step heating process, the particles were annealed for 0.5 h at each selected temperature. It was found that the deformation and interdiffusion temperatures of the micro-PS particles are ca. 120-130degreesC and 140-150degreesC, that of the nano-PS particles are 90degreesC and 100-110degreesC respectively. The DSC traces of nano-PS particles showed that there was an exothermic peak near T-g after annealing for 0.5 h at the selected temperatures below 90degreesC; otherwise, the exothermic peak disappeared after annealing at 100degreesC or above. Compared with the micro-PS particles, the sintering process of nano-PS particles occurs at much lower temperature determined by the confined state of polymer chains with higher conformational energy in nano-particles, and completes in a much narrower temperature range driven mainly by the larger total surface energy.

Size Effects of the Critical Temperature in Ferroelectric Thin Films

The size effects of the critical behaviors for the systems of interacting spins are discussed extensively inliterature.In this paper,the finite-size dependence of the critical temperature and susceptibility of the ferroelectric thinfilm are investigated numerically based on the four-state Potts model with the nearest-neighbor interactions between thedipole moments.The four orientations of the domains exist in the ferroelectric film and the movement of the domainwalls determines the polarization switching process besides the boundary conditions of the film.The critical exponentsare obtained and our investigations show that the boundary conditions play the important roles for the ferroelectricproperties of the thin films and the critical behavior of the thin films strongly depends on the feature of the surface.

Size Effect of Electromagnetic Constitutive Characteristics of Ultrathin Al Films

The ultrathin aluminum films with thickness in the range of 2～60 nm have been deposited by dc magnetron sputtering apparatus. Reflectance and transmittance of the obtained samples were measured with a WFZ-900-D4 UV/VIS spectrophotometer. The optical constant (n, k) and permittivity (ε', ε') were determined by applying Newton-Simpson recurrent substitution method. The results indicate that the electromagnetic constitutive characteristic of ultrathin aluminum films is a function of thickness and has obvious size effect.

FLOWING FILM JIGGING FUNCTION IN THE NEW″IFFC″PROCESS FOR SEPARATING MINERALS OF ULTRAFINE SIZES

The concept of the flowing film jigging was first applied to the flowing film concentration area.The flowingfilm jigging function is an important element of the new process,in jection-flowing film centrifugation(IFFC),for separating and recovering minerals of ultrafine sizes.

Bauschinger and size effects in thin-film plasticity due to defect-energy of geometrical necessary dislocations

The Bauschinger and size effects in the thinfilm plasticity theory arising from the defect-energy of geometrically necessary dislocations （GNDs） are analytically investigated in this paper. Firstly, this defect-energy is deduced based on the elastic interactions of coupling dislocations （or pile-ups） moving on the closed neighboring slip plane. This energy is a quadratic function of the GNDs density, and includes an elastic interaction coefficient and an energetic length scale L. By incorporating it into the work- conjugate strain gradient plasticity theory of Gurtin, an energetic stress associated with this defect energy is obtained, which just plays the role of back stress in the kinematic hardening model. Then this back-stress hardening model is used to investigate the Bauschinger and size effects in the tension problem of single crystal Al films with passivation layers. The tension stress in the film shows a reverse dependence on the film thickness h. By comparing it with discrete-dislocation simulation results, the length scale L is determined, which is just several slip plane spacing, and accords well with our physical interpretation for the defect- energy. The Bauschinger effect after unloading is analyzed by combining this back-stress hardening model with a friction model. The effects of film thickness and pre-strain on the reversed plastic strain after unloading are quantified and qualitatively compared with experiment results.

陶瓷基复合材料编织结构参数对气膜冷却效果影响研究

针对陶瓷基复合材料(CMC材料)在航空发动机高温部件中应用时的冷却需求,考虑到CMC材料内部非均质非均匀结构和热物性特征与均质金属材料的巨大差异,探究了CMC材料编织结构几何参数对气膜综合冷却效果的影响,研究中以三维五向编织CMC材料为例,建立了反映材料内部细观编织结构的平板气膜全尺寸计算模型,从细观纱线尺度引入各组分热物性参数,计算分析了不同编织角度和纤维束截面尺寸等几何特征参数对气膜综合冷效的影响规律。研究结果表明,纤维束由于导热系数相对较高成为平板内部的主要热量传输通道,编织角发生变化时纤维束方向也随之改变,进而影响材料内部热量传输通道及整体各向异性等效导热系数。本文计算工况下,在气膜孔下游0~10D (D为气膜孔直径)区域,编织角度为40°时气膜综合冷效相对较高;在远离气膜孔区域,气膜板的冷却效果随着编织角度的增大而减弱。纤维束截面尺寸的改变对气膜综合冷效的影响较小,但是随着纤维束截面尺寸的增加,平板内部温度更加均匀。

水性有机硅改性环氧树脂的制备与性能

利用二甲基二氯硅烷(DMDCS)与环氧树脂E51中-OH缩合反应合成有机硅改性环氧树脂,并采用相反转法制备水性有机硅改性环氧树脂,以疏水性优选有机硅改性环氧树脂合成条件,分析了乳化工艺对乳液平均粒径的影响,并考察了固化膜性能。结果表明,在环氧树脂40 g、DMDCS 1.6 g、溶剂用量20 mL、50℃反应8 h的条件下,有机硅改性环氧树脂与水的接触角为106.8°;当乳化剂用量为25%、乳化温度为65℃、剪切机转速为3000 r/min时,乳液平均粒径为1.011μm,储存稳定性(30 d)和离心稳定性(3000 r/min,30 min)良好;水性有机硅改性环氧固化膜固化时间短,具有优良的疏水性、力学性能、耐腐蚀性能。

薄涂细粉末涂料性能研究

采用扫描电镜、激光粒度仪等手段分析表征了粉末涂料粒径对涂层表面的光泽度、流动性、上粉率、回收率及喷涂面积的影响。试验结果表明,当粉末涂料的粒径为30μm时,涂层的光泽度高达85%,30 s内流出量为150 g,上粉率和回收率分别为60%和63%,且得到的涂层表面效果较好,光滑细腻。与常规粉末涂料相比,薄涂细粉末涂料的平均膜厚减少39.4μm,节省粉末涂料用量79.5%。薄涂细粉末涂料性能整体优良,能满足喷粉型材产品生产和使用的需要。

环氧树脂乳化剂的合成及其乳液的性能评价

以环氧树脂E-44为主要原料制备了水性环氧乳液。研究了乳化剂掺量对乳液粒径特征、贮存稳定性和离心稳定性的影响,并测试了最佳乳化剂掺量下乳液胶膜的基本性能。结果表明:随着乳化剂掺量的增加,乳液微粒逐渐向粒径更小的方向迁移,贮存稳定性与离心稳定性均逐渐提升。当乳化剂掺量大于18%时,乳液平均粒径减小幅度与稳定性提升幅度均放缓,推荐乳化剂掺量为18%~24%。乳化剂掺量为18%时的乳液胶膜固化后铅笔硬度为3 H,柔韧性为1 mm,附着力为1级,具有较好的耐水耐酸性。

山地果树微锥四方形覆膜技术

水资源的缺乏和降雨量的不均匀严重制约着农业生产的可持续发展,采用山地果树微锥四方形覆膜技术有助于解决山地果树干旱和降雨量不均匀等引起的果树干旱胁迫和花芽分化少等一系列问题。采用山地果树微锥四方形覆膜技术起垄能够节水保墒,提高水分利用率;选择覆盖黑色地膜可以在春季提温保墒,提高水分利用率,防止杂草生长;利用四面横竖双沟既能在干旱少雨的春季起到集雨的作用,又能在秋季多雨的季节分流雨水,有效控制果树的营养生长,从而促进果树花芽分化。

磷酸二氢铵与硅烷偶联剂在纺织浆料中的应用与研究

利用INSTRON万能强力仪、傅里叶红外光谱仪、X射线衍射仪等仪器,探讨磷酸二氢铵加入由磷酸酯淀粉与丙烯酸酯组成的共混浆料的时机,研究磷酸二氢铵和硅烷偶联剂KH580处理的共混浆料,所形成浆膜的成分和结晶度,以及对织物的上浆率。研究结果表明:磷酸二氢铵在共混浆料糊化前加入,对共混浆料性能的提升效果更好。磷酸二氢铵会降低浆膜的结晶度,改善浆料的渗透性能,增加浆膜的强力。硅烷偶联剂对浆膜强力影响较小。两者共同作用时对浆膜性能有增强作用。改变硅烷偶联剂的加入量对上浆率的影响不明显,但增加磷酸二氢铵的加入量,织物上浆率增加。

尾砂粒级组成对胶结充填料流变特性与强度的影响

为探究尾砂粒级组成与充填料流变特性及强度之间的关系,采用全尾砂、旋流器分级溢流和底流尾砂经人工配制成5种尾砂充填料,开展了不同粒级组成尾砂充填料流变与强度试验。结果表明:随着尾砂中-38μm细粒级含量的增加,充填料浆屈服应力和塑性黏度增加,且-38μm细粒级含量越高充填料浆屈服应力和塑性黏度增加幅度越大;随着细粒级尾砂含量的增加,水化膜厚度呈先增加后降低的变化趋势;充填料浆初始屈服应力和塑性黏度受水化膜厚度和固体颗粒比表面积的双重影响;当细粒级尾砂含量超过44.37%时,水化膜厚度与充填料浆初始屈服应力和塑性黏度之间存在负指数关系。随着细粒级尾砂含量的增加,尾砂充填体强度先增加后减小,细粒级含量为44.37%时为尾砂最佳粒级组成,此时充填体中尾砂堆积所形成的骨架结构最密实,充填体总孔隙率、平均孔径和大于0.2μm有害孔占比最小。

催化剂BCE-H 200在高密度聚乙烯装置上的应用

在中韩(武汉)石油化工有限公司Hostalen ACP高密度聚乙烯装置上,采用国产催化剂BCE-H 200分别替代进口催化剂Z 501和Z 509生产了高密度聚乙烯注塑料和薄膜料。分析对比了3种催化剂的活性及粉料粒径分布、堆积密度,并对生产的注塑料和薄膜料进行了表征分析。结果表明:BCE-H 200的活性较Z 501低13.8%,较Z 509高49.2%,其氢调敏感性较Z 501和Z 509低;BCE-H 200生产注塑料和薄膜料时,粉料的粒径分布比进口催化剂Z 501和Z 509更集中,细粉更少,但堆积密度低;采用催化剂BCE-H 200替代催化剂Z 501生产的注塑料刚性较高,韧性较低,相对分子质量分布更宽;采用催化剂BCE-H 200替代催化剂Z 509生产的薄膜料,力学性能变化不大,相对分子质量分布更宽。

Fatigue of metals at nanoscale: Metal thin films and conductive interconnects for flexible device application

As electrodes and electrical interconnects in flexible electronic devices,metal films are one of the weakest components in the system against mechanical deformation in daily use.Fatigue reliability at nanoscale becomes a practical concern for these flexible electronic devices.This review introduces state-of-the-art fatigue testing techniques and evaluation methods for thin metal films and conductive interconnect materials constrained by a substrate.Then,experimental results about fatigue damage behaviors,fatigue properties and fatigue life prediction are summarized.Furthermore,fundamental insights into fatigue mechanisms of metals at the nanoscale and the size effects on fatigue properties are elucidated.Finally,the perspectives of studies on fatigue of thin metal films constrained by a substrate are proposed.

Grain Size and Wettability of TiO_2/SiO_2 Photocatalytic Composite Thin Filing

The uniform transparent TiO2/SiO2 photocatalytic composite thin films are prepared by sol-gel method on the soda lime glass substrates, and characterized by UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), BET surface area, FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that the addition of SiO2 to TiO2 thin films can suppress the grain growth of TiO2 crystal, increase the hydroxyl content on the surface of TiO2 films, lower the contact angle for water on TiO, films and enhance the hydrophilic property of TiO2 films. The super-hydrophilic TiO2/SiO2 photocatalytic composite thin films with the contact angle of 0((o) under bar) are obtained by the addition of 10%-20% SiO2 in mole fraction.

Effect of Starch Dodecenylsuccinylation on the Adhesion and Film Properties of Dodecenylsuccinylated Starch for Polyester Warp Sizing

A series of dodecenylsuccinylated starches( DSSs) with different degree of substitution( DS) were prepared via the esterification of dodencenylsuccinic anhydride with hydrolyzed cornstarch in aqueous dispersion for investigating the influences of starch dodecenylsuccinylation upon the performances such as apparent viscosity and surface tension of starch paste, film behaviors,and adhesion to fibers for warp sizing. It was found that the dodecenylsuccinylation was able to reduce the surface tension of cooked starch paste and enhance the adhesion of starch to polyester fibers. It was also capable of depressing the brittleness of native starch and improving the mechanical behaviours such as breaking elongation and work-to-break of starch film. Initial increase in DS level of dodecenylsuccinylation enhanced these positive effects,while excessively increasing the level resulted in marked reduction in tensile strength of starch film and significant decrement in reaction efficiency. X-ray diffraction patterns of starch films showed the dodecenylsuccinates derivatized onto the backbones of starch depressed the degree of crystallinity of starch film. Based on the paste behaviors, adhesion, and film properties, the dodecenylsuccinylation level is recommended in a range of 0. 015-0. 025 for sizing polyester warps.