Papers by Author: Wei Zhang

Abstract: This paper reviews the development of levitation melting technology including the equipment production, fundament research and applied development from 1981 to 2012, moreover, introduces the new progresses after 2010 from different aspects including improved levitation ability, increased melting temperature, increased equipment specification, and combining levitation melting with modern technologies of the material science, and so on. The development of advanced materials preparation by using levitation melting technology also is introduced in this paper.

Abstract: Based on mobile Internet technology applications, Customers access ladder price electricity price standard, the implementation, such as power charge information. Change the way traditional electricity propaganda, tips, rich ladder price electricity price means of propaganda, tips. Improve the enforcement ladder price electricity price propaganda, strengthen the publicity and guide ladder price electricity price, improve the various circles of society to the understanding and awareness of the residents ladder price electricity price policy. Tariff and other policies to promote in the future suggesting that provides technical application support for the implementation of the price ladder policy to create a good atmosphere.

Abstract: Periodic mesoporous organosilica film was prepared via sol-gel and spin-coating methods using a 1, 2-bis (triethoxysilyl) ethane (BTEE) and a poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) triblock copolymer template (P123). Thermal treatment at 350°C for 1h resulted in the formation of ultralow dielectric constant (k) film with a k value of 1.82, a leakage current density of 1.58×10^-9 A/cm² at 0.5MV/cm, Youngs modulus of 6.45 GPa, and hardness of 0.58 GPa. Further, thermal treatment at higher temperature up to 500°C still achieves an ultralow k value smaller than 2.0, similar leakage current characteristics, and enhanced mechanical properties. These indicate that synthesized PMO film has robust thermal stability, and very good potential for the application of next-generation inter-level dielectrics.

Abstract: As the interaction mechanism between disc-cutter and wall rock is the key to the TBM performance of breaking-rock, many exports who come from different countries have so far made a great deal of studies, tests, analyses and modeling works and many models of mechanism of rock-fragmentation were achieved. Some new corrections are made constantly according to the experiences accumulated from engineering practice. This paper summarizes the works of the scholars and some analyses and comparisons are made. Based on the CSM and NTNU, a new model is presented to takes into account some ingredients, which would influence the efficiency for TBM to break wall rock. To enhance the level of design, manufacture and operation of TBM, the databases for rock attributes, main parameters of TBM and excavating parameters should be found.

Abstract: The pure aluminized layer and RE-aluminized layer on industrial pure iron were prepared by hot dip aluminizing method, and the thickness and composition of the layer were investigated by means of scanning electronic microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The results showed that the RE was permeated into the alloy layer after hot dip RE-aluminizing and the thickness of the alloy layer increases by about 30% as against hot dip pure aluminizing. The binding energy between the vacancy and aluminum atom was calculated. According to the energy condition of the solute-vacancy complex diffusion, it points out that the solute-vacancy complex diffusion is the main mechanism of aluminum atoms diffusion in hot dip RE-aluminizing and the main reason why the thickness of alloy layer increases after hot dip RE-aluminizing.

Abstract: The effects of rotating electromagnetic stirring and inoculants on the solidification structures and properties of IN100 superalloy vacuum investment casting was studied with XRD, SEM and optical microscope. The results show that by initiating the 50Hz, 150A rotating electromagnetic stirring as soon as the molten metal was poured into the mould, which was coated with inoculant CoAl₂O₄, the average equiaxed grain size of IN100 superalloy vacuum investment casting can be refined to 95μm and the fraction of equiaxed grains can be increased to 99 %. On condition that the grain size of K417 superalloy vacuum investment casting were refined to 95μm, the tensile properties at room temperature, the morphology of （γ＋γ′）eutectic and the morphology of dendrites can be greatly improved.

Abstract: Intermetallic compounds layer will be formed at the interfaces between alloy layer and matrix in the diffusion process of hot dip aluminized steel, which is beneficial to enhance the binding ability of alloy layer with matrix. However, when the thickness of intermetallic compounds exceeds the certain value, the vast extending force of interfacial void will cause the crack of intermetallic compounds and greatly weaken the spall resistance of aluminized layer. Therefore it is very important for the applications of hot dip aluminized steel to research and control the formation of intermetallic compounds at the interfaces. According to the characteristics of diffusion process of hot dip aluminized steel, the growing model of intermetallic compounds were established in the paper. The computed results were in accord with the experimental value. It can provide reference to the choice of the diffusion parameters of hot dip aluminized steel.

Abstract: The aluminized layer and the La-aluminized layer on 20 carbons steel were prepared by hot dip aluminizing method, and the microstructure and composition of the layer were investigated through scanning electronic microscopy (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) and energy dispersive spectroscopy (EDS). The results showed that the amorphous phase was found in the surface layer of the hot dip aluminized steel. In order to study the phenomenon, the Al-Fe alloy liquids used in hot dip aluminizing were quickly solidified and slowly solidified respectively. The results showed that the amorphous phase was found in all Al-Fe alloy samples under the condition of the quick solidification. While the amorphous phase was only found in Al-Fe alloy sample with La under the condition of the slow solidification. Moreover, the pure amorphous alloy exists in the parts region of the sample, and the weight percentages of Al and Fe in pure amorphous alloy was 23: 2, and the amorphous alloy composition also contains a small quantity La. The formation mechanisms of the amorphous phase and behavior of La in the hot dip aluminized layer were also discussed.

Abstract: The influence of the content of rare-earth La on the microstructure and corrosion-resistance of hot-dipped aluminum was studied in this paper .The results show that ,under the same technology conditions, the thickness of hot-dipped aluminizing layer by adding the appropriate content of rare-earth La is about 2～3 times as much as that without rare-earth La, and the microstructure of hot-dipped aluminizing layer has also greatly changed ,and a great deal of phase Fe3Al was precipitated along the boundary of a phase. The corrosion resistance of the hot-dipped layer with rare-earth La is greatly increased.

Abstract: The commercial hot-rolled bars of LD10 alloy (grain size 25~75µm) are pretreated via proper recrystallization annealing (temperature 380°C, 420°C and 460°C) and solution annealing (temperature 500°C). The average elongation is increased from 158% to 270%, 223%, 219% and 233% respectively and the maximum elongation is 321% (500°C, 3.3×10-4s-1). The test results show that the alloy can present certain superplasticity owing to structural effect of dynamic recrystallization refining during superplastic deformation of coarse-grained LD10 alloy. Large and deep cavities form in grain boundaries and result in intergranular fracture after larger superplastic tensile deformation. And a large amount of metal filaments appear on grain surfaces. The formation of filaments is attributed to viscous flow of solid-liquid mixture in grain boundaries caused by grain-boundary sliding. The appearance of solid-liquid mixture makes grain-boundary sliding easier.