High-temperature Resistance Performance of An Inorganic Adhesive for Concrete Structures Strengthened with CFRP Sheets

Organic epoxy matrices have been widely used in the FRP reinforcing technique, but they have serious disadvantages of poor high-temperature resistance. An inorganic adhesive is invented to replace the organic adhesive. For the inorganic adhesive at normal temperature and different high temperatures, the microstructure and phase composition are investigated by means of X-ray diffraction （XRD） and SEM respectively. Results show that inorganic adhesive can resist at least 600 ℃ high temperature. Fire-resistance performance of inorganic adhesive can meet the requirements of fiber reinforced polymer （FRP） strengthened RC structures.

Dependence of Performance of Organic Light-emitting Devices on Sheet Resistance of Indium-tin-oxide Anodes

The dependence of the performance of organic light-emitting devices（OLEDs） on the sheet resistance of indiumtin-oxide（ITO） anodes was investigated by measuring the steady state current density brightness voltage characteristics and the electroluminescent spectra. The device with a higher sheet resistance anode shows a lower current density, a lower brightness level, and a higher operation voltage. The electroluminescence（EL） efficiencies of the devices with the same structure but different ITO anodes show more complicated differences. Furthermore, the shift of the light-emitting zone toward the anode was found when an anode with a higher sheet resistance was used. These performance differences are discussed and attributed to the reduction of hole injection and the increase in voltage drop over ITO anode with the increase in sheet resistance.

Sheet Resistance and Gas-Sensing Properties of Tin Oxide Thin Films by Plasma Enhanced Chemical Vapor Deposition

Tin oxide (SnO2) thin films are prepared at different temperatures by plasmaenhanced chemical vapor deposition (PECVD). The structural characterizations of the films are investigated by various analysis techniques. X-ray diffraction patterns (XRD) show that the phase of SnO2 films are different at different deposition temperatures. The sheet resistance of the films decreases with increase of deposition temperature. X-ray photoelectron spectroscopy (XPS) shows that the SnO2 thin film is non-stoichiometric. The sheet resistance increases with increase in oxygen flow. Sb-doped SnO2 thin films are more sensitive to alcohol than carbon monoxide, and its maximum sensitivity is about 220%.

Peeling behavior and spalling resistance of CFRP sheets bonded to bent concrete surfaces

In this paper, the peeling behavior and the spalling resistance effect of carbon fiber reinforced polymer （CFRP） sheets externally bonded to bent concrete surfaces are firstly investigated experimentally. Twenty one curved specimens and seven plane specimens are studied in the paper, in which curved specimens with bonded CFRP sheets can simulate the concrete spalling in tunnel, culvert, arch bridge etc., whereas plane specimens with bonded CFRP sheets can simulate the concrete spalling in beam bridge, slab bridge and pedestrian bridge. Three kinds of curved specimens with different radii of curvature are chosen by referring to practical tunnel structures, and plane specimens are used for comparison with curved ones. A peeling load is applied on the FRP sheet by loading a circular steel tube placed into the central notch of beam to debond CFRP sheets from the bent concrete surface, meanwhile full-range load-deflection curves are recorded by a MTS 831.10 Elastomer Test System. Based on the experimental results, a theoretical analysis is also conducted for the specimens. Both theoretical and experimental results show that only two material parameters, the interfacial fracture energy of CFRP-concrete interface and the tensile stiffness of CFRP sheets, are needed for describing the interfacial spalling behavior. It is found that the radius of curvature has remarkable influence on peeling load-deflection curves. The test methods and test results given in the paper are helpful and available for reference to the designer of tunnel strengthening.

Effects of Cover Sheets on the Nugget Growth and Fracture Behavior of Resistance Spot Welded Q&P980 Steel Joints

The resistance spot weldability of galvanized ultra-high-strength steels is not satisfed,the joints are prone to interfacial fracture and the weldable current range is narrow.To solve the problems,a novel method called resistance spot welding with double-sided cover sheets was introduced to weld a galvanized Q&P980 steel with the thickness of 1.2 mm.Two thin SPCC mild steel sheets were chosen as cover sheets and were placed symmetrically at both sides between the Q&P980 steels and the electrodes,then the RSW process was carried out.Compared with the traditional RSW method,the joints obtained by using the novel method achieved larger tensile shear strength and energy absorption,which increased by 26.9%and 52.6%,respectively.With increasing the welding current,the failure mode transferred from interfacial fracture to nugget pull-out fracture or base metal tearing fracture.By contrast,the joints always showed interfacial fracture without cover sheets.The improvement of the joint performance was mainly attributed to the enlargement of the nugget.With the help of fnite element simulation,it was found that the cover sheets helped increase the contact area and reduced the current density during welding,which postponed the expulsion,and a larger area could be evenly heated.The application of the novel method can be easily extended to the resistance spot welding of other ultra-high-strength steels with various thicknesses.

Calculated and Experimental Research of Sheet Resistances of Laser-Doped Silicon Solar Cells

The calculated and experimental research of sheet resistances of crystalline silicon solar cells by dry laser doping is investigated. The nonlinear numerical model on laser melting of crystalline silicon and liquid-phase diffusion of phosphorus atoms by dry laser doping is analyzed by the finite difference method implemented in MATLAB. The melting period and melting depth of crystalline silicon as a function of laser energy density is achieved. The effective liquid-phase diffusion of phosphorus atoms in melting silicon by dry laser doping is confirmed by the rapid decrease of sheet resistances in experimental measurement. The plateau of sheet resistances is reached at around 15 Ω/. The calculated sheet resistances as a function of laser energy density is obtained and the calculated results are in good agreement with the corresponding experimental measurement. Due to the successful verification by comparison between experimental measurement and calculated results, the simulation results could be used to optimize the virtual laser doping parameters.

Low Sheet Resistance Counter Electrode in Dye-sensitized Solar Cell

In order to search for the high efficiency and low sheet resistance counter electrode in dye-sensitized solar cell, we used Ti plate as the conducting substrate to prepare the counter electrode by thermal decomposition of H2PtCl6. Ti plate counter electrode shows low sheet resistance, good reflecting performance and matching kinetics. The dye-sensitized solar cell with the Ti plate counter electrode shows better photovoltaic performance than that of the cell with the fluorine-doped tin oxide-coated glass counter electrode.

Biomimic Vein-Like Transparent Conducting Electrodes with Low Sheet Resistance and Metal Consumption

In this contribution,inspired by the excellent resource management and material transport function of leaf veins,the electrical transport function of metallized leaf veins is mimicked from the material transport function of the vein networks.By electroless copper plating on real leaf vein networks with copper thickness of only several hundred nanometre up to several micrometre,certain leaf veins can be converted to transparent conductive electrodes with an ultralow sheet resistance 100 times lower than that of state-of-the-art indium tin oxide thin films,combined with a broadband optical transmission of above 80%in the UV–VIS–IR range.Additionally,the resource efficiency of the vein-like electrode is characterized by the small amount of material needed to build up the networks and the low copper consumption during metallization.In particular,the high current density transport capability of the electrode of>6000 A cm^−2 was demonstrated.These superior properties of the vein-like structures inspire the design of high-performance transparent conductive electrodes without using critical materials and may significantly reduce the Ag consumption down to<10%of the current level for mass production of solar cells and will contribute greatly to the electrode for high power density concentrator solar cells,high power density Li-ion batteries,and supercapacitors.

Biodiesel Resistance of Thin Resin Cr-Free Steel Sheets for Fuel Tank

The content of biodiesel mixed with diesel fuel were compared to inspect the fuel resistance of thin resin Cr-free steel sheets, which are widely used as steel sheets of automobile fuel tank. Some additives which can be presented during the process of biodiesel preparation were added for CCT (Cyclic Corrosion Test). These additives can accelerate the occurrence of corrosion. The corrosion was appeared on the coating and painting layer and in serious cases even substrate material was corroded. For methanol, mixing with blended fuel showed the reduction in corroded area as the additive concentration was reduced in the mixed fuel. Especially the peroxide hydrogen showed the strongest corrosiveness. It is known that formic acid has a tendency of weaker corrosiveness than peroxide hydrogen, but the corrosion is occurred throughout the specimen. Water is not mixed well with fuel, and does not seem to impact on corrosion significantly. However, water is easily mixed with other additives and is considered to facilitate the corrosion by other additives.

Study of doping uniformity of a 200 kV ion implanter by RBS and sheet resistance measurements

The ion implantation uniformity is of vital importance for an ion implanter.In this paper,we report the,uniformity measurement for a large current ion implanter(LC-16 type) by implanting of 190-keV Ar ions into Si to 3×1016 atoms/cm2,followed by Rutherford backscattering spectroscopy(RBS) and sheet resistance measurement providing quantitative information on spatial distribution of dopants.The implant doses obtained from RBS at selected points of the sample give a spatial uniformity of <5%,which are confirmed by the sheet resistance measurement.While sheet resistance is an indirect method for dose evaluation of ion-implanted samples,RBS provides a competent technique for calibration of the ion implantation system.And both measurements show that good uniformity can be achieved for the ion implanter by tuning of the scanning process.

Flexural behavior of composite beams after the ultimate limit state externally strengthened with CFRP sheets bonded with high-temperature resistant matrix

In this paper the alkali-activated slag cementitious materials(AASCM)which strength at 600 ℃ is larger than that of AASCM at room temperature,were prepared to paste CFRP sheets to strengthen four simply supported unbonded prestressed composite beams encased circular steel tube truss after ultimate limit state.Test on flexural behavior of these four beams was performed.Moreover,normal section load-bearing capacity of these beams and the curve load-deflection at mid-span were obtained.Experimental results show that it is feasible to strengthen concrete members with CFRP sheets bonded with AASCM.Based on the experimental results and theoretical study,computational method of stiffness is proposed for calculating bending rigidity and normal section load-bearing capacity of concrete simply supported beams strengthened with CFRP sheets bonded with AASCM.Formula of bending rigidity calculation was founded which results are in good agreement with testing data.

适用于共晶焊的肖特基二极管背面金属化工艺优化

[目的]为了降低成本,减少污染,提高工艺效率,对肖特基二极管背面金属化工艺进行研究,探索锡锑合金替代金系合金的最佳不持温镀膜金属化工艺.[方法]通过持温镀膜与不持温镀膜对比实验,分析电子束蒸发镀膜基片温度对阴极金属层间黏附性和导电性,以及薄膜厚度对空洞率的影响,得到适用于批量共晶焊的肖特基二极管背面金属化最优工艺参数.[结果]当基片温度为180℃时,不持温镀膜的剪切力为64.53 N,高于持温镀膜的剪切力;当金属化锡锑合金膜厚为3μm时,共晶焊的空洞率低于5%,符合共晶焊要求;电子束蒸发镀膜背面金属层方块电阻随基片温度升高先减小后增大,温度在180~240℃之间,方块电阻随基片温度的变化不大.[结论]用于共晶焊的肖特基二极管背面金属化的最优工艺为基底温度升到180℃后在自然降温的同时进行多层金属镀膜,锡锑合金镀膜厚度为3μm.

抗方阻波动的超宽带轻薄频率选择表面吸波体

满足宽带、极化和入射角度稳定、轻薄和强吸收等高性能要求的电阻膜频率选择表面(FSS)吸波体设计难度大,且易因加工中方阻波动导致吸波性能变化.为此,本文首先分析了方阻波动影响电阻膜FSS吸波体性能的机理,提出抗方阻波动的FSS吸波体设计方法.在此基础上,提出利用不同层FSS阻抗随频率变化互补的扩展带宽方法,结合弯折小型化设计,获得了超宽带、极化和角度稳定的轻薄型抗方阻波动FSS吸波体.该FSS吸波体在TE和TM极化下,90%吸波带宽为1.50—20.50 GHz(相对带宽173%),厚度仅为0.093λ_(L).TE极化波80%吸波的角度稳定性可达45°,而TM极化波90%吸波的角度稳定性可达70°.当每层FSS方阻在12—30Ω/sq范围内波动时,吸波体的90%吸波带宽仍保持在167.0%.实验测试结果与仿真结果基本吻合,证明了所提方法的有效性.

汽车轻量化材料表面处理技术创新研究

基于铝材在车身中占比的不同,对钢铝混合车身材料的表面处理技术进行创新研究。研究表明:当使用传统磷化工艺对钢铝混合车身材料进行表面处理时,冷轧板、镀锌板和铝板表面均形成均匀致密的磷化膜,铝板产渣量低于4 g/m^(2);应用后处理工艺对钢铝混材进行表面处理时,铝板在后处理工艺的磷化槽液中不生成磷化膜,而经过钝化工序处理后表面形成钝化膜,铝材在磷化液中的产渣量低于0.5 g/m^(2);当使用无磷化成工艺对钢铝混材进行表面处理时,钢铝混合车身材料可以同槽形成Zr化膜,且所有板材形成的残渣量低于0.2 g/m^(2)。

板材平整度对锆化膜耐蚀性能的影响研究

为了从机理上明确锆化膜的耐蚀性与基材表面平整度的关系,通过化学抛光分别改变冷轧板、铝合金板表面平整度,与未处理的冷轧板、铝板进行对比,在试样表面制备锆化膜,利用扫描电镜(SEM)分别观测锆化膜的微观形貌;利用电化学方法、盐雾试验箱、循环交变试验机、漆膜附着力检测设备等仪器测试钝化膜的耐蚀性能、漆膜附着力。结果表明:抛光后的冷轧板、铝合金板外观光滑平整,制备的锆化膜颗粒排布均匀致密,粗糙度明显降低,锆化膜的腐蚀电流较小,阻抗半径较大;未抛光的冷轧板、铝合金板外观粗糙不平整,制备的锆化膜颗粒大小不一,排布无规律;冷轧板、铝合金板锆化膜经冲击、杯突和划格实验的附着力检测后结果合格;经1000 h盐雾测试后,抛光后平整表面的冷轧板漆膜单边最大扩蚀宽度约1.9 mm,漆面无气泡;未抛光冷轧板漆膜单边最大扩蚀宽度约2.3 mm,漆面无气泡;抛光铝合金板经过30个循环交变检测后,漆膜单边扩蚀宽度2.0 mm,漆面无气泡;未抛光铝合金板经过30个循环交变检测后,漆膜单边扩蚀宽度2.6 mm,漆面无气泡。

交/直流薄膜方块电阻测试系统设计与分析

四探针法测量薄膜方块电阻具有测量精度高、稳定性好等优点,被广泛应用于薄膜器件制备、半导体微区掺杂等领域。为了提高薄膜方块电阻的测试速度及精度,以改进的范德堡法原理为基础,采用压控电流源方式输出稳定的电流,利用LabVIEW软件搭建了一套能使用交/直流测量薄膜方块电阻的测试系统。为了验证该测试系统的合理性及测试速度,选取Pt金属薄膜作为被测样品进行方块电阻的测量。测试结果表明,直流法和交流法都能精确测量薄膜方块电阻,直流法和交流法的单次测试时间分别为0378 s和0317 s,系统的测试速度优于商用280SI半导体设备。交流法测试Pt金属薄膜方块电阻的抗干扰能力比直流法强。该系统为被测样品选取合适的测试电流和测试方法提供了参考,对薄膜样品进行变温电阻率连续测量具有重要意义。

一种适用于板桩与土体相互作用的p-y曲线折减方法

p-y曲线法可充分考虑土体的塑性变形及抗力极限值,但该方法是基于单桩水平静载试验提出的一种桩土弹簧计算方法,无法直接应用于板桩与土体的相互作用。通过引入p-y曲线折减系数,提出一种适用于板桩与土体相互作用的p-y曲线折减方法,将其结果与Plaxis有限元模型计算结果及现场位移观测结果进行对比,并验证该方法的准确性。结果表明,该方法可以充分考虑土弹簧的非线性及土体地基反力极限值,弥补了m法和p-y曲线方法的不足。

钨镍共掺杂V_(2)O_(5)薄膜的光电特性研究

利用溶胶–凝胶旋涂法和后退火工艺在FTO导电玻璃上制备了钨镍共掺杂V_(2)O_(5)薄膜,研究了薄膜在不同温度和不同偏压下的光电特性和相变特性。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X射线光电子能谱仪(XPS)测试了钨镍共掺杂V_(2)O_(5)薄膜的晶体结构、表面形貌和组分,分析了不同钨镍共掺杂浓度对V_(2)O_(5)薄膜相变光电特性的影响。结果表明,当钨和镍的掺杂质量分数分别为3%和1.5%时,钨镍共掺杂的V_(2)O_(5)薄膜的相变温度为218.5℃,在可见光范围内有较高的透过率,在近红外1310 nm波长处的光学透过率达48.83%,与未掺杂V_(2)O_(5)薄膜的光学透过率相比提高了10.29%,薄膜电阻降低了30.53%,热致回线宽度收窄为15℃,说明钨镍共掺杂的V_(2)O_(5)薄膜具有良好的可逆相变光电特性,有望在新型光电器件领域得到较好的应用。

中铝锌铝镁无铬自润滑产品的表面特性

[目的]中铝锌铝镁钢板亟需一款适合微电机使用场景的自润滑膜层。[方法]通过对中铝锌铝镁表面3种无铬自润滑产品的表面微观形貌及膜层成分进行探究,分析了不同表面处理方式的各项性能,并结合自润滑产品的组成特性及实际使用场景,考察了不同自润滑膜层的耐蚀性、耐磨性等关键性能,明晰了造成各项性能差异的原因。[结果]与1#及2#有机弱酸性体系无铬自润滑产品相比,3#有机-无机复合自润滑膜层是偏无机酸性体系,与钢板表面的界面反应更强,具有较好的附着力,耐蚀性、耐指纹性、导电性、耐磨性等性能也更优。[结论]3#无铬自润滑产品膜层中的磷酸根为腐蚀抑制剂,磷酸盐又是隔离层与粘结层的有效成分,可进一步提高膜层的抗腐蚀能力。氟钛酸作为该涂层的润滑添加剂,不仅充当了提高润滑涂层耐蚀性的缓蚀剂,还充当了填充剂,填充于膜层孔隙中,有利于致密自润滑膜的形成,有效地减小了摩擦因数,提高了成型性能。

汽车车身常用板材耐腐蚀性能研究

车身常用板材的耐腐蚀性能是车身板材选用的重要参考标准,因此,对已加工为零件的热浸镀铝硅镀层板、未加工为零件的热浸镀铝硅镀层板、电镀锌板、热镀锌板、热成型钢裸板和冷轧板分别进行裸板材板和电泳板的中性盐雾对比试验。结果表明:有镀层的板材耐腐蚀性能明显优于无镀层板材;热浸镀铝硅镀层板加工成零件后其镀层会被破坏,导致其裸板耐腐蚀性能下降,但其电泳板的耐腐蚀性能加工前后变化不大,划痕扩蚀情况反而提升;热成型钢裸板因加工过程形成的氧化膜和脱碳层,在中性盐雾条件下4 h即出现锈蚀,其电泳板和电泳划痕板中性盐雾试验均出现严重的起泡问题。