Effect of nanoclay on properties of porous PVdF membranes

The main requirements for battery separators are high porosity which can serve pathways of lithium ion and space for gel electrolytes to impregnate in a membrane and mechanical strength to allow easy handling for battery assembly. Generally, it appears the trade-off relationship between the porosity and mechanical strength of the membrane. PVdF composite membranes containing nano-size clays were used to improve the mechanical strength of the membrane without affecting the membrane porosity. The composite me...     

Optimal design considering structural efficiency of compressed natural gas fuel storage vessels for automobiles

The shape and thickness of the dome were investigated with the aim of optimizing the type II CNG storage vessels by using a finite element analysis technique. The thickness of the liners and reinforcing materials was optimized based on the requirement of the cylinder and dome parts. In addition, the shape of the dome, which is most suitable for type II CNG storage vessels, was proposed by a process of review and analysis of various existing shapes, and the minimum thickness was established in this sequence: metal liners, composite materials and dome parts. Therefore, the new proposed shape products give a mass reduction of 4.8 kg(5.1%)     

F-Si封闭剂对热喷涂15%Al-85%Zn合金涂层电化学行为的影响(英文)

大部分船体外壳通过喷漆、牺牲阳极和外加电流阴极保护方法来解决抗腐蚀问题。但是,这些传统的方法不是非常有效,因为船尾的船舵常暴露在严重的腐蚀环境中,例如潮汐、船行驶速度、气蚀和冲刷腐蚀。由于气泡的生成与破裂而产生的振荡波而导致的气蚀和冲刷腐蚀会对材料产生破坏。对热喷涂Al-Zn合金涂层进行了气蚀和电化学性能测试实验。然后,Al-Zn合金涂层表面涂刷F-Si封闭剂以提高Al-Zn涂层的耐海水电化学腐蚀和抗气蚀性能。结果表明,该封闭剂不但适用静态环境,而且适用于动态环境。     

Lubrication properties of silver-palladium alloy prepared by ion plating method for high temperature stud bolt

As a solid lubricant, silver-palladium (Ag-Pd) alloy coating was investigated for the application to high temperature stud bolt. A glue layer nickel (Ni) film was deposited on the surface of the hex bolt sample and then Ag-Pd alloy coating was performed on it using ion plating method. The friction coefficient of Ag-Pd alloy film coated bolt was lower than that of N-5000 oil coated bolt by the result of axial force measurement. The cyclic test of heat treatment was conducted to evaluate the durability of Ag-Pd alloy film coated bolt. In a cycle, sample was assembled into the block using torque wrench, followed by heating and disassembling. It was not successful to disassemble the N-5000 oil coated bolt from the block after only one cycle. However, the Ag-Pd alloy film coated bolt was able to be disassembled softly till 12 cycles.     

Effect of CaO composition on oxidation and burning behaviors of AM50 Mg alloy

Oxidation and burning behaviors were studied for CaO added AM50 Mg composites which were manufactured by conventional melting and casting processes without SF6 protective gas. CaO added AM50 Mg composites show the stable oxidation resistance, while AM50 Mg alloys show the poor oxidation resistance. The effects of CaO addition on the burning resistance under ambient, nitrogen and dry air atmospheres were examined for CaO added AM50 Mg composites. With increasing CaO addition, the burning temperature increase...     

Dispersion of ultrafine SiC particles in molten Al-12Si alloy

The bulk Al-12 Si eutectic composites were fabricated through a conventional liquid metal casting route, especially with the help of ultrafine ceramic powders made by self-propagating high-temperature synthesis (SHS) process. The SHS powders were fabricated by the chemical reaction between micro-sized SiC and Al particles at very high combustion temperatures, producing the coarse Al particles (several tens of microns) containing ultrafine SiC ceramic particles. Microstructural observation revealed that the ...     

Structural considerations in friction welding of hybrid Al_2O_3-reinforced aluminum composites

Comparative studies on the relationship between the welding parameters and joining efficiency in the friction welding of hybrid Al2O3-reinforced aluminum composites were conducted. Metal matrix composites (MMCs) with 37% (volume fraction) aluminum particle were joined by friction welding. The results show that the effects of the rotation speed on the reduction rate of particle size are greater than those of the upset pressure, and the area of the MMC weld zone decreases as the joining efficiency increases, ...     

CO_2 laser-micro plasma arc hybrid welding for galvanized steel sheets

A laser lap welding process for zinc-coated steel has a well-known unsolved problem-porosity formation. The boiling temperature of coated zinc is lower than the melting temperature of the base metal, which is steel. In the autogenous laser welding, the zinc vapor generates from the lapped surfaces expels the molten pool and the expulsion causes numerous weld defects, such as spatters and blow holes on the weld surface and porosity inside the welds. The laser-arc hybrid welding was suggested as an alternative method for the laser lap welding because the arc can preheat or post-heat the weldment according to the arrangement of the laser beam and the arc. CO2 laser-micro plasma hybrid welding was applied to the lap welding of zinc-coated steel with zero-gap. The relationships among the weld quality and process parameters of the laser-arc arrangement, and the laser-arc interspacing distance and arc current were investigated using a full-factorial experimental design. The effect of laser-arc arrangement is dominant because the leading plasma arc partially melts the upper steel sheets and vaporizes or oxidizes the coated zinc on the lapped surfaces. Compared with the result from the laser-TIG hybrid welding, the heat input from arc can be reduced by 40%.     

Signcryption with fast online signing and short signcryptext for secure and private mobile communication

Signcryption scheme is one of the useful tools for secure communication where authenticity and confidentiality are simultaneously required.Now,mobile devices are more and more widely used for communication,and thus it is desirable to design a scheme suitable to mobile applications.In this paper,we propose a signcryption scheme which is efficient enough to be implemented on mobile devices.In our scheme,we need only one multiplication in an online phase,and thus a signcryptor can generate a signcryptext very efficiently in the online phase.Moreover,the size of signcryptext is very short compared with exsiting schemes,and thus our scheme is very efficient in terms of communication overhead.The security of our signcryption scheme is proven in the random oracle model.     

与环境烟气相关的挥发性有机物的特性

本项研究测定了环境烟气(ETS)中的多种挥发性有机物,在环境实验室中目标化合物的唯一来源就是ETS。实验室中的ETS是由燃吸肯塔基参考卷烟和其他8种市售卷烟产生的。在12轮试验中同时测定了30多种化合物。目标化合物分为3类,即:气相ETS标识物3乙基吡啶(简称3-EP)与烟碱、羰基化合物(包括甲醛)和挥发性有机化合物(简称VOCs)。利用环境实验室研究结果可以确定各种VOCs与3-EP(气相ETS标记物)的特征比率,另外还可以用来估测与ETS相关的VOCs的散发因子。总体说来,本项研究测得的特征比率与以往已经发表的实验室研究数据是一致的,这意味着,"真实"室内环境受多种来源的复杂的混合物影响。本项研究测定的特征比值也可以用于ETS目标化合物的定性和定量分析