Surface Tension and Its Temperature Coefficient of Molten Tin Determined with the Sessile Drop Method at Different Oxygen Partial Pressures

The surface tension of molten tin has been determined by the sessile drop method at The surface tension of molten tin has been determined by the sessile drop method at temperatures ranging from 523 to 1033 K and in the oxygen partial pressure (P-O2) range from 2.85 x 10(-19) to 8.56 x 10(-6) MPa, and its dependence on temperature and oxygen partial pressure has been analyzed. At P-O2 = 2.85 x 10(-19) and 1.06 x 10(-15) MPa, the surface tension decreases linearly with the increase of temperature and its temperature coefficients are -0.151 and -0.094 mNm(-1) K-1, respectively. However, at high P-O2 (3.17 x 10(-10), 8.56 x 10(-6) MPa), the surface tension increases with the temperature near the melting point (505 K) and decreases above 723 K. The surface tension decrease with increasing P-O2 is much larger near the melting point than at temperatures above 823 K. The contact angle between the molten tin and the alumina substrate is 158-173degrees, and the wettability is poor.

Effects of superimposed pulse bias on TiN coating in cathodic arc deposition

Orthogonal designs are used to investigate the main factors when doing experiments in which pulse bias is superimposed on d.c. bias during cathodic are deposition of TiN. Pulse peak, duty cycle, frequency, direct voltage, are current and pressure all are investigated when coating TiN on HSS substrates. Roughness, surface micrograph, microhardness and thickness are tested. By analysis of variance, it is shown that pressure and frequency are the main factors. R-a and droplet density of the film with (d.c. + pulse) bias decrease. A simple explanation for the result is suggested.

Substrate Effects on the Micro/Nanomechanical Properties of TiN Coatings

Nanoindentation and nanoscratch tests were performed for titanium nitride (TiN) coatings on different tool steel substrates to investigate the indentation/scratch induced deformation behavior of the coatings and the adhesion of the coating–substrate interfaces and their tribological property. In this work, TiN coatings with a thickness of about 500 nm were grown on GT35, 9Cr18 and 40CrNiMo steels using vacuum magnetic-filtering arc plasma deposition. In the nanoindentation tests, the hardness and modulus curves for TiN/GT35 reduced the slowest around the film thickness 500 nm with the increase of indentation depth, followed by TiN/9Cr18 and TiN/40CrNiMo. Improving adhesion properties of coating and substrate can decrease the differences of internal stress field. The scratch tests showed that the scratch response was controlled by plastic deformation in the substrate. The substrate plays an important role in determining the mechanical properties and wear resistance of such coatings. TiN/GT35 exhibited the best load-carrying capacity and scratch/wear resistance. As a consequence, GT35 is the best substrate for TiN coatings of the substrate materials tested.

Thermocapillary Flows In Liquid Bridges Of Molten Tin With Small Aspect Ratios

Numerical simulations were conducted to study thermocapillary flows in short half-zone liquid bridges of molten tin with Prandtl number Pr = 0.009, under ramped temperature difference. The spatio-temporal structures in the thermocapillary flows in short half-zone liquid bridges with aspect ratios As = 0.6, 0.8, and 1.0 were investigated. The first critical Marangoni numbers were compared with those predicted by linear stability analyses (LSA). The second critical Marangoni numbers for As = 0.6 and 0.8 were found to be larger than that for As = 1.0. The time evolutions of the thermocapillary flows exhibited unusual features such as a change in the azimuthal wave number during the three-dimensional stationary (non-oscillating) flow regime, a change in the oscillation mode during the three-dimensional oscillatory flow regime, and the decreasing and then increasing of amplitudes in a single oscillation mode. The effects of the ramping rate of the temperature difference on the flow modes and critical conditions were studied as well. In this paper, the experimental observability of the critical conditions was also discussed. (C) 2008 Elsevier Inc. All rights reserved.

过滤电弧沉积的TiN/TiCrN/CrN/CrTiN多层膜

用过滤电弧技术在高速钢表面沉积了TiN/TiCrN/CrN/CrTiN多层膜 ,用扫描电镜 (SEM )观察了截面和断口形貌及划痕后的形貌。使用俄歇电子谱仪进行剥层成分分析 ,用纳米压痕仪测试了多层膜和单层膜的显微硬度和弹性模量。结果表明 ,在调制周期大于 10 0nm时 ,多层膜的显微硬度符合Hall Petch关系 ,在 80nm时 ,则脱离线性关系。划痕法测试多层膜的结合力达到 80N。

过滤电弧沉积TiN、ZrN和TiN／CrN多层纳米薄膜的性能比较

用过滤电弧离子镀(FAMIP)技术在高速钢基体上沉积了TiN、ZrN单层薄膜和TiN／CrN多层纳米薄膜。利用扫描电子显微镜(SEM)观察了薄膜及其划痕的表面形貌;用X射线衍射仪(XRD)分析了薄膜的相组成,结合显微探针仪、划痕试验机、金相显微镜和钻床,研究了金属陶瓷单层和多层纳米薄膜的性能并进行比较。研究结果表明:3种薄膜的临界载荷值均大于80N,多层纳米薄膜的耐磨性明显优于2种单层薄膜。

电弧离子镀中脉冲偏压对TiN,CrN薄膜性能的影响

在电弧离子镀技术中使用脉冲偏压电源是近年来发展起来的一项新技术。研究表明，在薄膜沉积过程中，以直流偏压为基础，迭加一个高脉冲电压，有助于改善薄膜的性能，并且能够在较低的沉积温度下获得结合力较强、内应力较小、表面光洁度也比较好的薄膜。通过正交设计和方差分析，本文首次研究了在电弧离子镀技术中使用脉冲偏压电源， 在高速钢和不锈钢基体上沉积TiN和CrN的过程中，对薄膜的表面粗糙度、表面形貌、结合力、显微硬度、沉积速率等性能的影响，发现：（1） 在考虑气氛、弧电流和脉冲电源的各种参数的情况下，气氛和频率是影响薄膜性能的主要因素；（2）在气氛、弧电流不变的条件下，脉冲电源的频率和占空比是影响薄膜粗糙度的主要因素；（3）在比较了直流偏压和脉冲偏压的实验结果之后，认为利用直流迭加脉冲的偏压方式，经过优化参数，能够比较显著地 降低薄膜的表面粗糙度，提高沉积速率。

Formation and characterization of tin oxide aerogel derived from sol-gel process based on tetra(n-butoxy)tin(IV)

Transparent and translucent SnO2 aerogels with high specific surface area (>300m(2)/g) have been prepared by sol-gel process using tetra(n-butoxy)tin(IV) as a starting compound, and supercritical drying technique for solvent extraction. Light scattering measurements reveal that the polymeric cluster size distribution in sol system is gradually broadened during sol-gel transition. SEM images show that the aerogels are made up of the cottonlike oxide agglomerates with a large number of Pores. TEM images show that these aerogels seem to be self-similar at different magnifications. Their pore size distribution is pretty wide ranging, from mesopore to macropore especially for that of translucent aerogel. (C) 2004 Elsevier B.V. All rights reserved.

金属薄膜与半导体的反应——Co-Si多层膜，LREM硅化物薄膜，TiN/n-GaAs体系

Submitted by zhangdi (zhangdi@red.semi.ac.cn) on 2009-04-13T11:45:31Z

Characterization of free-standing GaN substrate grown through hydride vapor phase epitaxy with a TiN interlayer

Large-scale GaN free-standing substrate was obtained by hydride vapor phase epitaxy directly on sapphire with porous network interlayer. The bottom surface N-face and top surface Ga-face showed great difference in anti-etching and optical properties. The variation of optical and structure characteristics were also microscopically identified using spatially resolved cathodoluminescence and micro-Raman spectroscopy in cross-section of the GaN substrate. Three different regions were separated according to luminescent intensity along the film growth orientation. Some tapered inversion domains with high free carrier concentration of 5 x 10(19) cm(-3) protruded up to the surface forming the hexagonal pits. The dark region of upper layer showed good crystalline quality with narrow donor bound exciton peak and low free carrier concentration. Unlike the exponential dependence of the strain distribution, the free-standing GaN substrate revealed a gradual increase of the strain mainly within the near N-polar side region with a thickness of about 50 mu m, then almost kept constant to the top surface. (c) 2007 Elsevier B.V. All rights reserved.

Magnetic properties of tin-doped magnetite nanoparticles

Structural and magnetic characteristics of Fe3-xSnxO4 (x < 0.3) nanoparticles synthesized using the precipitation exchange method have been investigated by X-ray diffraction, transmission electron microscope, Mossbauer spectra, X-ray photoelectron spectroscopy and magnetization measurement. The mean particle dimension decreases from 8 to 6 nm, the lattice parameters enlarge, the saturation magnetization decreases, as well as the magnetization and the coercive field increase, with increasing tin-content. The paramagnetic property of the specimens indicates that the replacement of Fe3+ by Sn4+ on the octahedral sites of Fe3O4 causes a progressive lowering of the Curie temperature and the Curie temperatures of the materials are all lower than that of crystallite tin-doped magnetite. This striking debasing is due to the lessening of the grain size. This is the smallest size reported thus far for paramagnetic tin-doped magnetite particles. (c) 2006 Elsevier B.V. All rights reserved.

Influence of indium-tin-oxide thin-film quality on reverse leakage current of indium-tin-oxide/n-GaN Schottky contacts

Indium-tin-oxide (ITO)/n-GaN Schottky contacts were prepared by e-beam evaporation at 200 degrees C under various partial pressures of oxygen. X-ray photoemission spectroscopy and positron beam measurements were employed to obtain chemical and structural information of the deposited ITO films. The results indicated that the observed variation in the reverse leakage current of the Schottky contact and the optical transmittance of the ITO films were strongly dependent on the quality of the ITO film. The high concentration of point defects at the ITO-GaN interface is suggested to be responsible for the large observed leakage current of the ITO/n-GaN Schottky contacts. (c) 2006 American Institute of Physics.

Electroluminescence afterglow from indium tin oxide/Si-rich SiO2/p-Si structure

Indium tin oxide/Si-rich SiO2/p-Si structured devices are fabricated to study the electroluminescence (EL) of the Si-rich SiO2 (SRO) material. The obvious peaks at similar to 1050nm and similar to 1260nm in the EL are ascribed to localized state transitions of amorphous Si (alpha-Si) clusters. The EL afterglow associated with alpha-Si clusters is observed from this structure at room temperature, while the afterglow is absent in the case of optical pumping. It is believed that carrier-induced defects act as trap centres in the alpha-Si clusters, resulting in the EL afterglow. The phenomenon of the EL afterglow indicates the limits of EL performance and electrical modulation of the SRO material with a larger fraction of alpha-Si clusters.

Photovoltaic effect of tin disulfide with nanocrystalline/amorphous blended phases

Tin disulfide (SnS2) nanocrystalline/amorphous blended phases were synthesized by mild chemical reaction. Both X-ray diffraction and transmission electron microscopy measurements demonstrate that the as-synthesized particles presented very small size, with a diameter of only a few nanometers. The photoluminescence (PL) spectrum suggests efficient splitting of photo-generated excitons in poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) and SnS2 hybrid films. Organic/inorganic hybrid solar cells comprising MDMO-PPV and SnS2 were prepared, giving photovoltage, photocurrent, fill factor and efficiency values of 0.702 V, 0.549 mA/cm(2), 0.385 and 0.148%, respectively, which suggests that this phase-blended inorganic semiconductor can also serve as a promising solar energy material. (C) 2009 Elsevier Ltd. All rights reserved.