Effects of low melting point metals(Ga,In,Sn) on hydrolysis properties of aluminum alloys

Low melting point metals（Ga, In, Sn） as alloy elements were used to prepare Al-In-Sn and Al-Ga-In-Sn alloys through mechanical ball milling method. The effects of mass ratio of In to Sn and Ga content on the hydrolysis properties of aluminum alloys were investigated. X-ray diffraction（XRD） and scanning electron microscopy（SEM） with energy disperse spectroscopy（EDS） were used to analyze the compositions and morphologies of the obtained Al alloys. The results show that the phase compositions of Al-In-Sn ternary alloys are Al and two intermetallic compounds, In3 Sn and In Sn4. All Al-In-Sn ternary alloys exhibit poor hydrolysis activity at room temperature. Al-In-Sn alloy with the mass ratio of In to Sn equaling 1：4 has the highest hydrogen yield. After Ga is introduced to the ternary alloys, the hydrolysis activity of aluminum alloys at room temperature is greatly improved. It is speculated that the addition of Ga element promotes the formation of defects inside the Al alloys and Ga-In3Sn-In Sn4 eutectic alloys on the alloys surface. Al atoms can be dissolved in this eutectic phase and become the active spots during the hydrolysis process. The small size and uniform distribution of this eutectic phase may be responsible for the enhancement of hydrolysis activity.

Multi-Point Forming Technology for Sheet Metal

Multi-point forming (MPF) is an advanced manufacturing technology for three-dimensional sheet metal parts. In this paper, the MPF integrated system is described that can form a variety of part shapes without the need for solid dies, and given only geometry and material information about the desired part. The central component of this system is a pair of matrices of punches, and the desired discrete die surface is constructed by changing the positions of punches though the CAD and control system. The basic MPF process is introduced and the typical application examples show the applicability of the MPF technology. Wrinkle and dimple are the major forming defects in MPF process, numerical simulation is a feasible way to predict forming defects in MPF. In conventional stamping, the mode to form sheet metal with blankholder is an effective way to suppress wrinkling; the same is true in MPF. A MPF press with flexible blankholder was developed, and the forming results indicated the forming stability of this technique. Based on the flexibility of MPF, varying deformation path MPF and sectional MPF were explored that cannot be realized in conventional stamping. By controlling each punch in real-time, a sheet part can be manufactured along a specific forming path. When the path of deformation in MPF is designed properly, forming defects will be avoided completely and lager deformation is achieved. A work piece can be formed section by section though the sectional MPF, and this technique makes it possible to manufacture large size parts in a small MPF press. Some critical experiments were performed that confirmed the validity of two special MPF techniques.

PROMOTER FLOW ACTION OF SOLID-STATE LOW MELT POINT METAL ON THE POLYPROPYLENE

With the aid of a slip-disentanglemnt theory, a rheological equation has been deduced about the composite system of solid-state low melting point metal and polymer. By measuring some rheological properties of the composite system composed of low melt point metal and polypropylene (LMPM/PP), the results show that LMPM has a promoter flow action upon PP when using a small amount of LMPM and, if some coupled agents are added, the promoter flow action will be remarkable. Moreover, while LMPM being added into the composite, the temperature sensitivity of system will go rip. This indicates that the system's viscosity will drop further if its temperature is increased.

FABRICATION OF HIGH-MELTING POINT METAL COATING

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MESHFREE METHOD BASED ON POINT COLLOCATION FOR METAL FORMING SIMULATION

A meshfree method based on reproducing kernel approximation and point collocation is presented for analysis of metal ring compression. The point collocation method is a true meshfree method without the employment of a background mesh. It is shown that, in a point collocation approach, the remesh problem because of the mesh distortion in FEM （finite element method） and the low efficiency in Galerkin-based meshfree method are avoided. The corrected kernel functions are introduced to the stabilization of free-surface boundary conditions. The solution of symmetric ring compression problem is compared with a conventional finite element solution, and reasonable results have been obtained.

TREATMENT OF OBSTINATE PEPTIC ULCER AND CHRONIC GASTRITIS WITH A METAL RING EMBEDDED IN ZUSANLI ACUPOINT

We had treated 102 cases of obstinate peptic ulcer and chronic gastritis with ametal ring embedded in Zusanli acupoint since October 1989 to October 1992,and got satisfactorytherapeutic effects.The total effective rate is 96.08%,the cure rate of peptic ulcer is 87.32%,therecurrence rate is significantly lower than that of control group(P【0.001),and it has no side-effect.

DISPERSION AND IN SITU FORMED FIBER OF LOW MELTING POINT METALS IN POLYMER

The dispersion mechanism of low melting point metal (LMPM) particles in polymers was studied using Cox dilute emulsion model. The critical destruction shear stress sigma of LMPM droplets is sigma greater than 2 v/d. When sigma is small, LMPM droplets were dispersed and deformed ellipsoidal or bar droplets whose orientation direction is always at an angle of 45 degree with the direction of shear rate. When sigma is very big and droplets are very fine, polymer melt elasticity behavior and big boundary tension between a polymer melt and LMPM droplets make further fining LMPM droplets become more difficult. Therefore, LMPM droplets produce tensile flow and form LMPM microfibrils in situ in polymer melt. SEM photographs have shown the results predicted using dilute emulsion model. (Author abstract) 7 Refs.

Measurement of electrical conductivity of micron-scale metallic wires

Electrical conductivities of micron-scale aluminum wires were quantitatively measured by a four-point atomic force microscope (AFM) probe. This technique is a combination of the principles of the four-point probe method and standard AFM. This technique was applied to the 99.999% aluminum wires with 350 nm thickness and different widths of 5.0, 25.0 and 50.0μm. Since the small dimensions of the wires, the geometrical effects were discussed in details. Experiment results show that the four-point AFM probe is mechanically flexible and robust. The four-point AFM probe technique is capable of measuring surface topography together with local electrical conductivity simultaneously. The repeatable measurements indicate that this technique could be used for fast in-situ electrical properties characterization of sensors and microelectromechanical system devices.

Rheology in Processing of in Situ Composites of Polypropylene and Low Melting Poing Metals

The low melting point metallic tin powder or alloy of tin and lead was blended with polypropylene. A kind of in situ composite has been prepared. The variations of torque were studied when the composites were mixed in Haake torque rheogeniometer. By way of capillary extrusion, effects upon rheology of the in situ composites of the low melting point metals (LMPM) and coupling agent for their different variety and content, were investigated. From flow curves, the results indicate that in situ composites mixed with the LMPM are a kind of pseudoplastic fluid. If the LMPM were melted, the higher the content of the LMPM, the lower apparent viscosity of composites. Meanwhile, when the coupling agent is added into composites , the viscosity of composite will go up first and drop then. This shows that the LMPM have a promoter flow action on the polypropylene.

A New Thioamide Derivative for Separation and Preconcentration of Multi Elements in Aquatic Environment by Cloud Point Extraction

2-(pyridine-2-yl)-N-p-chlorohydrazinecarbothioamide (HCPTS) was synthesized, characterized and successfully applied for the preconcentration of Cu(II), Ni(II), Zn(II), Cd(II), Co(II), Pb(II), Fe(II), and Hg(II) in water, blood, and urine samples prior to graphite furnace atomic absorption determination (GFAAS);Hg was determined by cold vapor technique. Under the optimum experimental conditions (i.e. pH = 8, 10–4 M of HCPTS, 0.05% w/v of Triton X-114), calibration graphs were linear in the range of 0.02 to 200 ng?mL–1 for Co(II), Cd(II), Pb(II) and Ni(II);0.03 to 200 ng?mL–1 for Cu(II);0.07 to 200 ng?mL–1 for Fe(II) and Zn(II) and 0.02 to 150 ng?mL–1 for Hg(II). The enrichment factors were 43, 51, 41, 46, 54, 40, 45 and 52 for Cu(II), Ni(II),Zn (II), Cd(II), Co(II), Pb(II), Fe(II), and Hg(II), respectively. The limit of detection were found to be 0.019, 0.094, 0.0514, 0.052, 0.0165, 0.047, 0.068 and 0.041 ng?mL–1 for Cu(II), Ni(II), Zn(II), Cd(II), Co(II), Pb(II), Fe(II), and Hg(II), respectively. The developed method was applied to the determination of these metal ions in water, blood and urine samples with satisfactory results.

Trace Metal Concentrations in Pine Needles at Varying Elevation in Proximity to Roadways in an Urban Environment

Conifer needles bioaccumulate atmospheric pollutants, including trace metals, and may be used to monitor variations in atmospheric concentration. Needles were analyzed to determine whether a correlation exists between elevations and trace metal concentrations in proximity to roadways and other non-point sources. Composite samples of white spruce (Picea glauca) and balsam fir (Abies balsamea) needles were collected along hillsides in eastern and western Calgary, respectively. A combined total of 11 sites was sampled along two transects of increasing elevation. Qualitative and quantitative analysis of trace metal concentrations was completed using inductively coupled plasma-mass spectrometry (ICP-MS) and synthesized using regression analysis. The concentrations of cobalt, nickel, and calcium in the samples were found to exhibit a significant (P < 0.05) relationship with respect to elevation and proximity to roadways.

Microstructure and properties of an Al–Ti–Cu–Si brazing alloy for SiC–metal joining

An Al–Ti–Cu–Si solid–liquid dual-phase alloy that exhibits good wettability and appropriate interfacial reaction with SiC at 500–600°C was designed for SiC–metal joining. The microstructure, phases, differential thermal curves, and high-temperature wetting behavior of the alloy were analyzed using scanning electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, and the sessile drop method. The experimental results show that the 76.5Al–8.5Ti–5Cu–10Si alloy is mainly composed of Al–Al2Cu and Al–Si hypoeutectic low-melting-point microstructures (493–586°C) and the high-melting-point intermetallic compound AlTiSi (840°C). The contact angle, determined by high-temperature wetting experiments, is approximately 54°. Furthermore, the wetting interface is smooth and contains no obvious defects. Metallurgical bonding at the interface is attributable to the reaction between Al and Si in the alloy and ceramic, respectively. The formation of the brittle Al4C3phase at the interface is suppressed by the addition of 10wt% Si to the alloy. © 2017, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Fabry–Prot resonance coupling associated exceptional points in a composite grating structure

The exceptional point（EP） is a significant and attractive phenomenon in an open quantum system. The scattering properties of light are similar to those in the open quantum system, which makes it possible to achieve EP in the optic system. Here we investigate the EP in a Fabry–P′erot（F–P） resonant coupling structure. The coupling between different types of F–P resonances leads to a near zero reflection, which results in a degeneration of eigenstates and thus the appearing of EP. Furthermore, the multi-wavelength EPs and unidirectional invisibility can be achieved which may be used in integrated photonics systems.

Electromagnetic Modeling of Metallic Elliptical Plates

This paper presents the evaluation of the capacitance of an isolated elliptical plate and two parallel elliptical plates. Integral equations are formed by relating the previously unknown charges on the elliptical plates and the potential on the metallic plates. The integral equations are solved by applying the method of moments based on the pulse function and point matching. The elements of the matrix in the method of moments are found by dividing the structure into triangular subsections. The matrix equation is solved in order to compute the unknown charges on each subsection. Numerical results on the capacitance as a function of the geometrical parameters of the ellipse are presented.

X-ray detection based on complementary metal-oxide-semiconductor sensors

Complementary metal-oxide-semiconductor(CMOS) sensors can convert X-rays into detectable signals; therefore, they are powerful tools in X-ray detection applications. Herein, we explore the physics behind X-ray detection performed using CMOS sensors. X-ray measurements were obtained using a simulated positioner based on a CMOS sensor, while the X-ray energy was modified by changing the voltage, current, and radiation time. A monitoring control unit collected video data of the detected X-rays. The video images were framed and filtered to detect the effective pixel points(radiation spots).The histograms of the images prove there is a linear relationship between the pixel points and X-ray energy. The relationships between the image pixel points, voltage, and current were quantified, and the resultant correlations were observed to obey some physical laws.

多目标金属露天矿配矿装载点选取问题及求解算法

目的:为了减少矿产资源浪费,提高贫矿的利用率,针对大型金属露天矿多装载点配矿问题,综合考虑矿石剩余量不足、铲装设备数量有限等因素对配装载点选取的影响,以品位偏差最小、生产成本最小、车辆总排队时间最短为目标建立配矿装载点选取模型。方法:采用二维矩阵整数编码法,并设计一种基于随机片段交叉与特定变异算子相结合的间接二次遗传优化算法对模型进行求解。结果:以国内某大型金属露天矿实际生产数据为例进行仿真实验,结果表明:所得出的装载点选取方案在受铲装设备数量限制、优先开采矿石剩余量相对较少装载点的条件下,仍能满足配矿计划需求。结论:所提模型、算法能普遍适用于大型金属露天矿山开采,使装载点的矿石得到充分利用。意义:提高了企业的经济效益和矿山整体开采效率。

Experimental Studies of Self Healing Behaviour of Under-Aged Al-Mg-Si Alloys and 60Sn-40Pb Alloy Reinforced Aluminium Metal-Metal Composites

Experimental studies to demonstrate self healing potentials of Al-Mg-Si alloy were undertaken in this research work. Self healing exploring secondary precipitation in the Al-Mg-Si alloy and use of low melting metallic alloy reinforcement (60Sn-40Pb alloy) were used as basis for the investigation. For the precipitation study, the Al-Mg-Si alloy was under-aged at temperature of 160oC for 10 minutes and then subjected to second step ageing treatment at four different temperatures within the range of 25oC and 70oC. In the 60Sn-40Pb alloy reinforced Al-Mg-Si alloy study, the samples were prepared in pre-cracked state and then subjected to healing heat-treatment at 250oC. For all cases tensile test and healing efficiency was used to analyze the results generated. It was observed that a second step thermal ageing at 50oC resulted in peak improvement in tensile strength, yield strength, toughness and percent elongation while ageing above this temperature lead to a drop in the tensile properties in comparison to that of the sample not subjected to a second ageing treatment. Also the use of 60Sn-40Pb alloy as reinforcement in the Al-Mg-Si alloy resulted in a healing efficiency of 91% after pre-cracking and heat-treatment. The satisfactory bonding between the 60Sn-40Pb alloy and the Al-Mg-Si alloy matrix contributed to the high healing efficiency observed.

Metallic Iron and Nickel in Cretaceous and Cenozoic Sediments: The Results of Thermomagnetic Analysis

With the aid of thermomagnetic analysis (TMA) up to 800&#186;С the composition and distribution of particles of native iron and Fe-Ni alloy was studied in 15 sections, Gams (Austria), Verhorechie and Selbuhra (Crimea), Kvirinaki and Tetritskaro (Georgia), Aimaki, Bass, Dzhengutaj, Madzhalis and Gergebil (North Caucasus, Russia), Klyuchi and Tep-lovka (Volga Region, Russia), Koshak (Kazakhstan), Kara-Kala and Khalats (Turkmenistan). The age of sediments varies from Miocene to Early Cretaceous. Iron particles are present at 521samples out of 921studied. Their percentage varies from 10-5% to 0.05%. The distribution consists of two groups: 1) “zero” group (iron is not found by TMA);2) group of logarithmic normal distribution with a differing modes. The global enrichment by iron particles in synchronous deposits of Miocene, Maastrichtian-Danian, Santonian and Cenomanian was discovered. With respect to nickel content, the iron particles fall into two groups: 1) nearly pure iron without nickel;and 2) iron with nickel content up to 20%, with modal value of 5%. The source of iron particles is the cosmic dust. Particles of pure nickel and the alloy containing more of 20% of nickel are very rare. Possibly, such particles are related mainly with impact events. A peak of elevated iron content with nearly constant nickel of 5-6% was found in almost all studied sections. It is a global effect which is not dependent of place and time of deposition of iron particles.

无缝钢管张力减径工艺减径率分配修正模型理论研究

无缝钢管张力减径工艺减径率分配是孔型分配合理与否的关键步骤,但其分配仍依赖于经验公式。从金属流动的角度分析了减径率的分配规律,在经验的基础上提出了“三点两段统合式”减径率分配修正模型。将修正模型得到的结果与传统模型计算结果以及企业生产数据相比,发现变化趋势相近,减径率和减径量变化曲线更加光滑,应用于生产有利于金属流动。

用于温度传感器原位在线校准的水三相点自动复现控制系统

温度传感器在长时间温度测量中会出现性能漂移导致测量误差,为现场实时校准温度传感器实现长期稳定的高精度测量,需要基于国际温标ITS-90规定的温度固定点,对传感器进行无人自主原位校准。水三相点是水、冰、气三相平衡共存的温度点,其温度为国际温标中的0.01℃固定点,是对传感器进行校准的最常用的固定温度点。水三相点瓶是再现水三相点的关键装置。相较于传统的玻璃外壳水三相点瓶,金属外壳的水三相点瓶更为耐用,更适用于自动原位校准。为了实现水三相点的自动浮现,根据高纯水自发相变原理,设计了一种基于半导体帕尔贴效应快速稳定复现水三相点的自动控制系统及其控制方法。利用热电制冷器(TEC)和温度控制器为金属水三相点瓶提供过冷环境,在基于模型的制冷调度算法控制下,实现了较长时间保持稳定的水三相点状态。实验室测试表明,该控制系统可以在150 min内达到0.01℃的温坪,并保持稳定的三相点温度20 min及温度波动度±1 mK。温度原位在线自动校准系统可以为深海、深空及偏远地区的高精度温度测量提供校准服务。