LI Ximing CHEN Jiayong Institute of Chemical Metallurgy
,
Academia Sinica
,
Beijing
,
ChinaR.KAMMEL Institut Für Metallurgie
,
Technische Universitt Berlin
,
Germany Research Assistant
,
Institute of Chemical Metallurgy
,
Academia Sinica
,
Beijing 100080
,
China
金属学报(英文版)
The influence of mechanical activation on the leaching behaviour of scheelite was studied by means of fine grinding in an attritor and subsequently HCl leaching in presence of PO_4~(3-). Results showed that after fine grinding in the attritor,the reaction rate of scheelite with HCl-Na_3PO_4 solution was remarkably increased,the extraction of W increased from about 8 to 99%.The IR spectra and X-ray diffraction analysis indicated that in addition to an enlargement of surface area the fine grinding action had made also changes of fine struc- ture and reactivity of solid surface,hence the leaching process of scheelite can be carried out under mild leaching conditions.
关键词:
scheelite
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null
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null
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null
LIU Chunpeng XU Yousheng HUA Yixin Kunming Institute of Technology
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Kunming
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650093
,
China.
材料科学技术（英文）
In applying the microwave radiation to extractive me- tallurgy,it is essential first of all to find the extent of microwave energy absorbed by various minerals experi- mentally.In this paper,more than 25 kinds of common useful minerals have been individually irradiated by a 500 W,2450 MHz microwave source in an enclosed quartz crucible to ascertain their heating temperature in a definite time.In addition,the reduction and cbloridization tests were also carried out on the titanomagnetite concentrate and pentlandite with microwave heating,respectively. These experiments indicate potential applications of util- izing microwave energy in extractive metallurgy.
关键词:
microwave radiation
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null
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null
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null
Z. T. Ma and D. Janke(Institute of Iron and Steel Technology
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Freiberg University of Mining and Technology
,
Germany)
金属学报(英文版)
Useder certain conditions, nonmctallic inclusions such as oxides, sulfides, nitrides and carbides are no longer harmful to sted service properties. With the new concept of oxide metallurgy, these properties can be improved by generating fine oxide inclusions which serve as heterogeneous nuclei for sulfide and fine ferrite[1-4]. A novel continuous casting (CC) process is expected to be created with the utilization of oxide metallurgy. This is also useful for the forthcoming technologies of direct rolling and near-net-shape casting. The main idea of oxide metallurgy consists of an alternative oxidation technology. It is based on steels treated by complex metals such as Ti, Zr, Ti-Zr alloys and rare earth metals. The selected deoxidants should follow the required conditions which are concluded in this paper.
关键词:
oxide
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null
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null
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null
Yong LIU
,
Lifang CHEN
,
Weifeng WEI
,
Huiping TANG
,
Bin LIU
材料科学技术（英文）
Ti-4.5Al-6.0Mo-1.5Fe, Ti-6Al-1Mo-1Fe and Ti-6Al-4V alloys were prepared by blended elemental powder metallurgy (PM) process, and the effects of Nd on the microstructures and mechanical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). It was found out that the addition of Nd increased the density of sintered titanium alloys slightly by a maximum increment of 1% because small amount of liquid phase occurred during sintering. The addition of Nd shows little effect on the improvement of tensile strength, while the elongation is significantly improved. For example, the elongation of Ti-4.5Al-6.0Mo-1.5Fe can be increased from 1% without addition of Nd to 13% at a Nd content of 1.2 wt pct.
关键词:
Powder metallurgy titanium alloy
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null
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null
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null
A.A.A. Saleh
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Y. Fu
,
X.J. Zhai
金属学报(英文版)
Nano-ZnO particle was produced by evaporating zinc powders in air at air °ow-rate
from 0.2 to 0.6m3/h. Nano-ZnO particles was formed by the oxidation of the evapo-
rated zinc vapor. X-ray di®raction shows the powders to be ZnO with lattice parame-
ters of a=0.3249nm and c=0.5205nm. The particle size is dependent upon the transit
time from the source to the collection area. The size of particles was ranged between
81 to 103nm. The average density resulted was 4.865g/cm3.
Normal ZnO and nano-ZnO were investigated to use them in aluminum metallurgy as
an inert anode material. A certain amount of both oxides were molded subsequently
inserted to the molten cryolite-aluminum oxide to investigate the corrosive behavior
of both oxides. When the sintering temperature increased up to 1300±C, the weight
loss ratio rose to 5.01%{7.33% and up to 7.67%{10.18% for nano-ZnO and normal
ZnO, respectively. However, when the samples in the molten cryolite aluminum oxide
were put for long time, the corrosive rate was found to be higher. It was found that
the corrosive loss weight ratio of nano-ZnO anode was much lower than the normal
one made from ordinary-ZnO providing that the nano-ZnO is more possible to be use
inert anode material.
关键词:
reactive evaporation method
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null
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null
新型炭材料
Chemical vapor deposition (CVD) is an effective way for the preparation of graphene with large area and high quality. In this review, the mechanism and characteristics of the four main preparation methods of graphene are briefly introduced, including micromechanical cleavage, chemical exfoliation, SiC epitaxial growth and CVD. The recent advances in the CVD growth of graphene and the related transfer techniques in terms of structure control, quality improvement and large area graphene synthesis were discussed. Other possible methods for the CVD growth of graphene were analyzed including the synthesis and nondestructive transfer of large area single crystalline graphene, graphene nanoribbons and graphene macrostructures.
关键词:
Graphene;Preparation;Chemical vapor deposition;Transfer;few-layer graphene;epitaxial graphene;large-area;carbon;films;surfaces;nickel;phase
Applied Physics Letters
We developed an ambient pressure chemical vapor deposition (CVD) for rapid growth of high-quality graphene films on Cu foils. The quality and growth rate of graphene films are dramatically increased with decreasing H(2) concentration. Without the presence of H(2), continuous graphene films are obtained with a mean sheet resistance of < 350 Omega/sq and light transmittance of 96.3% at 550 nm. Because of the ambient pressure, rapid growth rate, absence of H(2) and readily available Cu foils, this CVD process enables inexpensive and high-throughput growth of high-quality graphene films. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3512865]
关键词:
J.Koh
,
B.Kim
材料科学技术（英文）
We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomole-cular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) or “surface programmed assembly” method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.
关键词:
Chemical vapour deposition
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vapour
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deposition
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carbon
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nanotu
