Abstract: This work studies the aggregation of an synthetic ultraviolet absorbent, named 2-hydroxy-4-perfluoroheptanoate-benzophenone (HPFHBP), in the interface between two solvents which can not completely dissolve each other. The aggregation is studied by computer simulations based on a dynamic density functional method and mean-field interactions, which are implemented in the MesoDyn module and Blend module of Material Studios. The simulation results show that the synthetic ultraviolet absorbent diffuse to the interface phase and the concentration in the interface phase is greater than it in the solvents phase.
Abstract: The mid-IR and Raman spectra of geometrically frustrated atacamite hydroxyl copper chloride are measured by FTIR spectroscopy and HR800 Raman spectroscopy, respectively. The microscopic origins of bands within the functional group and the fingerprint regions are suggested by the known crystal structure parameters. Five distinct regions involved in hydroxyl stretching, overtones, hydroxyl deformation, Cu-O stretching, O–Cu–O symmetric stretching and O–Cu–O bending modes, pyramid-structure Cl≡Cu3 vibration modes, lattice modes, respectively.
Abstract: In order to control construction face instability of complex roof and predict roof collapse in deep coal mining, by numerical simulation, distribution of normal stress and interlayer separation of construction surface were calculated and influencing factors on separation of construction surface were analyzed in different conditions. The conclusions were drawn that original rock stress, rock characters, rock thickness and tunnel width had obvious influence and cohesion and friction angle of construction surface had little influence on separation of construction surface.
Abstract: In this paper Finite Element Method (FEM) was used to study the indentation behavior of aluminum alloy 2A12 with nonmetallic inclusions. Indentation elastic-plastic tests and indentation creep tests were simulated with a cylindrical indenter to analyze the influence of the inclusion size and the inclusion depth. FEM results indicate that the existence of inclusions will have certain influence on the indentation behavior, and when the inclusion size is close to the indenter size, the influence is obvious. For the indentation method, the conclusions can provide some useful information in the project application.
Abstract: The filler metal used during welding process is believed to play an important role on porosity formation in aluminium alloy welded. The present investigation is aimed to study the effect of different fillers ER4043 (Al-5%Si) and ER5356 (Al-5%Mg) on porosity formation of AA6061 alloy welded joints. Butt-joint welds were made on 6 mm thick plates using 21 – 22 V arc voltages by using Gas Metal Arc Welding process (GMAW). The hardness profile of each types of AA6061 welded joints for both fillers were characterized by the Vickers microhardness test. In order to study the formation and distribution of porosity, the images of analysis were obtained using the X- ray CT-Scan. It was observed that, more porosities were found in the alloy AA6061 using ER4043 compared to ER5356 filler metals with the percentage area value of porosity about 18.3 and 8.4%, respectively. The hardness profile of ER5356 and ER4043 welded materials exhibited the similar hardness pattern profile. It is proposed that Si and Mg contents in the filler metal could play significant role in the distribution of porosity. No significant effect was observed on the hardness profile for both filler metals of welded materials.
Abstract: Based on rolling-cut shear simulation, using a kind of single-shaft and double eccentricity rolling-cut shear, which adopts a new structure of asymmetric feature and negative bias, as the calculating model by establishing motion path equation of spatial shear mechanism, comparing with the steel shear forces, link forces and horizontal link force components with or without asymmetric feature, the asymmetric formulation is deduced. Such asymmetric crank structure can decrease horizontal force component between the linkages during rolling-cut process, increase the effective drive force on links while it comes to the maximum shear force, and decrease the extrusion of blade arc on steel edge as well. Theoretical analysis and steel-shearing quality at site indicate that asymmetric and negative bias is an important and efficient way to prolong the lifetime of blade, decrease blade wear, improve shearing quality, and maintain the constant clearance between blades.
Abstract: A life cycle assessment was carried out to estimate the environmental and economic impact s of pre-training electrolytic aluminum systems. The technology significantly contributed to non-carcinogens, respiratory inorganics, terrestrial ecotoxicity, global warming and non-renewable energy potential impacts. The technology played only a small role in the adverse impact of carcinogens, aquatic ecotoxicity, and mineral extraction categories, while the influence of the technologies on the way other elements affect the environment was ignorable. Specifically, the emissions from the aluminum oxides production and electricity consumption stages involved played an important role, while potential impact generated from transport, infrastructure, waste treatment, cryolite production, and aluminum fluoride production was quite small. Energy generation based on natural gas is an effective way to minimize overall environment impact. This research indicates that there are high potentials for improving environmental performance of the electrolytic aluminum production in China.
Abstract: This study focuses on the effect of stress and load towards hardness at epoxy mold compounds (EMCs) of a Quad Flat No- Lead (QFN) package using indentation technique. A series of three points bending cyclic test were performed with four different loads between 60 N to 120 N on QFN package. The nanoindentation with the maximum load of 300 mN was indented at five locations that perpendicular to the stress line on EMCs of QFN package after three points bending cyclic test were performed. The findings showed that the mean value of hardness was varied with load and stress. Higher load and stress were found to be not affected by hardness of EMCs. From the results, it is believed that the applied load and stress not play a role towards the hardness of EMCs. A polynomial relationship was plotted and shown that correlation of coefficient (R2) between stress and hardness of the studied EMCs was found to be at 97%. Finally, the finding suggested that a close correlation between the stress and hardness since it correlation coefficient gave a higher value with the polynomial relationship.
Abstract: Mg15Al-xNd (x=0, 0.5, 1.0, 1.5, 2.0and 4.0wt.%) alloys were prepared by metal mould casting method and the microstructures and mechanical properties were investigated. The results demonstrate that primary α-Mg grain is significantly refined with the addition of Nd element in Mg15Al alloy, and the best refinement is reached at 1.0wt.%Nd content. Further increasing Nd content leads to the coarsening of primary α-Mg grains. The added Nd element is also the reason of the refined eutectic β-Mg17Al12 and increased dispersion. The β-Mg17Al12 phase is thoroughly changed from fibrous coupled eutectic into divorced eutectic when Nd content reaches 1.5wt.%. Al11Nd3 phase is formed when the addition of Nd reaches to 1.0wt.% and Al2Nd phase emerges in the microstructure with increasing Nd content up to 4.0wt%. Addition of Nd element significantly improves the mechanical properties of Mg15Al alloy at room temperature. The best tensile strength and elongation is achieved by adding 1.0wt% Nd into Mg15Al alloy.
Abstract: A new wear resistance material named the hypoeutectic high carbon Fe-B cast steel with fine hard carbides dispersive distributed in the matrix have been investigated. The results show that the solidified structures of high carbon Fe-B steel consist of ferrite, pearlite and boride, and borides were distributed along grain boundary in interconnected network. After heat treatment, the metallic matrix changes into martensite and retained austenite. The eutectic borides are appeared to be less continuous network and isolated particles. The increasing of the quenching temperature leads to the improvement of hardness. Quenching at 980°C, impact toughness is increased with the increasing of the tempering temperature. The optimum heat treatment is quenching at 980°C(oil cooling) and tempering at 330°C(air cooling). The wear resistance of modified high carbon Fe-B cast steel is corresponding to Cr26 alloy. The impact wear mechanism is mainly plastic deformation and fatigue spalling.