Jiang QIN(School of Mechanical Engineering
,
University of Bath
,
Claverton Down
,
Bath BA27AY
,
UK)
材料科学技术（英文）
The variation principle is discussed and Rayleigh-Ritz method is proposed for construction of veloci ty field. A kinematically admissible velocity field based on polynomials was appIied to the determina tion of forging load and deformed buIge profile during upset forging of blocks. Simulation of upsetforging of rectangular blocks under various friction condjtions was performed. Comparison of the computed results with experiments and FEM shows good agreement. It is shown that this techniquecan be used for 3D simulation of metal forming process.
关键词:
X.K. Tao
,
X.Cong
,
R.S. Peng
,
J.Liu and Z.Y. Liu Tianjin Institute of Technology
,
Tianjin 300191
,
China
金属学报(英文版)
This paper investigates the effect of rare earth elements on the kinetic process, microstructure and mechanical properties of vanadization in borax bath. The results show that addition of rare earth elements to vanadizing agent has obvious catalytic effect on the rate of vanadization, which has been enchanced by 30%. The wear and corrosion resistance of vanadium carbide layer were prompted by the addition of rare earth to the agent. Through increasing vanadium potential of the agent, activating the surface of workpieces and decreasing the activation energy of diffusion of carbon, rare earth elements accelerate the rate of vanadization process.
关键词:
rare earth elements
,
null
,
null
QU Ying YANG Jian XU Baomei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
By use of the two-component LDA and high speed camera,the water model of the flow field in metal bath under molten slag layer has been tested.On the basis of experimental results,the flow boundary conditions of liquid metal at the slag-metal interface of a gas injecting bath were deduced.The flow field and the turbulent parameters of the metal bath covered with slag were solved by the vorticity-stream function method.The results reveal that the flow velocity, turbulent energy and circulating rate of the melt under slag are lower than that of without slagcover.Another one “dead zone” of the lowest turbulent energy is formed in the top layer under cover of slag near the ladle linning.
关键词:
flow field
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null
,
null
,
null
Haibin CHENG
,
Shuai XU
,
Wenyu ZHAO
,
Suling ZHAO
,
Pengcheng ZHAI
,
Zhigang SUN
,
Qingjie ZHANG
材料科学技术（英文）
Electroless CoNiWP magnetic films were prepared by varying the bath pH and then characterized by energy dispersive X-ray analysis, X-ray diffraction and magnetic force microscopy. It has been found that the microstructure and the magnetic properties of films were influenced greatly by the bath pH. At the bath pH 8.06, the grain size and coercivity of the films reach maximum, while the squareness (Mr=Ms) of MH curves reaches minimum. The Henkel plots indicates that the exchange-coupling interaction is very weak at this pH, which may be caused by phase-separation and large grain size, and then results in the lowest squareness. At pH above 8.5, obvious exchange-coupling interaction is observed because of the inexistence of phase-separation and the refinement of grain size.
关键词:
CoNiWP magnetic film
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Bath
,
pH
,
Squarenes
,
Exchang
HE Chun-lai
,
ZHU Rong
,
DONG Kai
,
QIU Yong-quan
,
SUN Kai-ming
钢铁研究学报(英文版)
A transient three-dimensional mathematical model has been developed to analyze the three-phase flow in a 150 t EAF (electric arc furnace) using oxygen. VOF (multiphase volume of fluid) method is used to simulate the behaviors of molten steel and slag. Numerical simulation was conducted to clarify the transient phenomena of oxygen impingement on molten bath. When oxygen jet impinges on the surface of molten bath, the slag layer is broken and the penetrated cavity in molten steel is created. Simultaneously, the wave is formed at the surface of uncovered steel on which the slag layer is pushed away by jet. The result of numerical simulations shows that the area and velocity of uncovered steel created by impingement, jet penetration depth change from 0.10 m2, 0.0125 m/s, 3.58 cm to 0.72 m2, 0.1445 m/s, 11.21 cm, when the flow rate of an oxygen lance varies from 500 to 2000 m3/h. The results have been validated against water model experiments. More specially, the relation between the penetration depth and oxygen flow rate predicted by numerical simulation has been found to agree well with that concluded by water model.
关键词:
electric arc furnace
,
three-phase flow
,
numerical simulation
W. Bensalah
材料科学技术（英文）
Thick and dense oxide layers were obtained on aluminium in sulphuric acid electrolyte. For this purpose, the methodology of experimental design was used. A three-variables Doehlert design (bath temperature, anodic current density, sulphuric acid concentration), was achieved. In order to maximize the growth rate and the density of the anodic oxide layer, optimum path study was conducted. Under the determined optimal anodizing conditions (5.7°C, 3 A·dm-2, Csul=140 g·L-1), the estimated response values were 0.86 μm·min-1 and 3.12 g·cm-2 for growth rate and density, respectively. The morphology of optimum layer was examined by scanning electron microscopy (SEM). The compactness of the optimum anodic layer can be correlated with its morphology revealed by SEM observations.
关键词:
Sulphuric anodization
,
null
,
null
,
null
Q. C. Le and J. Z. Cui School of Materials & Metallurgy
,
Northeastern University
,
Shenyang 110006
,
China
金属学报(英文版)
The 08 Al steel sheets were hot dip ped into Zn - Mn bath with 0 1 % Mn and 0 2 % Mn at600 ～420 ℃ bath tem perature , and then w ere treated in different w ays . The after - treat ments include cooling in the air at room tem perature directly , holding at the upper part of thehot dip galvanizing furnace for 60 s an d then holding at 510 ±10 ℃for 90 s . The results in dicated that blue , yellow , and purple , w hose coloration varied with the co m position an d thetem perature of bath and the w ays of after - treat ment . Finally , the mechanism of coloredzinc coating w as discussed .
关键词:
coloring hot dip galvanization
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null
,
null
Materials Chemistry and Physics
An electrodeposition procedure is performed in the Ni-plating bath containing multi-walled carbon nanotubes (MWNTs). The effects of MWNTs on the electrodeposits and process of Ni deposition are investigated by scanning electron microscopy, X-ray diffraction and electrochemical methods. The results show that there is an optimum concentration of MWNTs, at which the surface of the cathode can be uniformly and completely covered by MWNTs and thus Ni can be uniformly deposited on the MWNTs to form the MWNTs coated with a uniform Ni layer. The introduction of MWNTs in the Ni-plating bath increases the cathodic polarization of Ni deposition due to the two aspects as follows: The addition of MWNTs enhances the charge transfer for the reduction of Ni and also supplies a large active surface area for a great deal of nucleation of Ni, consequently results in an increase of concentration polarization. The deposition of Ni on the MWNTs requires the higher activation energy than that on the Cu. The MWNTs adsorbed on the cathode also induce Ni to deposit as smaller grains due to a large increase of nucleation sites of Ni. Therefore, more uniform and compact coating in appearance than Ni coating formed in the plating bath without MWNTs can be obtained. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
electrodeposition;MWNTs;Ni;polarization;coating;composite coatings;wear-resistance;load-transfer;microstructure;particles;mechanics;strength
Y.S.Huang
金属学报(英文版)
Electroless Ni-P-Zn alloys deposited from alkali bath were investigated in this paper. The deposition bath contained nickel sulfate, zinc chloride and hypophosphate. The process parameters, such as temperature, pH and zinc salt concentration were presented and discussed. The microstructure of the coatings was studied by XRD and SEM. The cathode glowing discharge characters of Ni-P-Zn depositions were studied with luminous Neon lamps. Electrodes deposited by electroless Ni-P alloys were apt to sputter during luminous working hours. Electroless Ni-P-Zn depositions improved the discharge characters of the electrodes. With the concentration of zinc in the deposition rising to 4wt, electrode sputter was largely restrained. The thickness of the deposition also influenced the discharge characters of the electrode. To avoid electrode sputter, the concentration of zinc has to rise with the thickness of the depositions.
关键词:
elctroless Ni-P-Zn alloy
,
null
,
null
