材料期刊网

A MIXED METHOD OF SOLUTION FOR CONTACT STRESSES ON ROLLER

Qu Zhihao Shanghai Technical College of Metallurgy , Shanghai , China PENG Huihong shanghai Institute of Non-Ferrous Metals , Shanghai , China Shanghai Institute of Non-Ferrous Metals.Shanghai , China

金属学报(英文版)

A mixed method of solution for contact stresses on rollers was suggested by the combina- tion of similitude principle.photoelastic method,Hertz's contact theory and numerical calculation.Thus,not only the distribution regularity of axial contact pressure on roller of limited length,but also the three-dimensional solution of stresses in the contact po- sitions may be obtained.An actual example is presented in the paper.It shows that the practical damaged phenomenon in real roller is in agreement with the result of the analysis

关键词: roller contact stress , null , null

Application of Microwave Radiation to Extractive Metallurgy

LIU Chunpeng XU Yousheng HUA Yixin Kunming Institute of Technology , Kunming , 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 , null , null , null

Optimization on technical parameters for fabrication of SDC film by screen-printing used as electrolyte in IT-SOFC

Journal of Physics and Chemistry of Solids

Sm-doped Ceria (SDC) electrolyte film was successfully fabricated on anode substrate of NiO-SDC by screen-printing. Some technical parameters for fabrication were investigated and optimized, including printing times, ink composition and sintering temperature. Scanning electron microscope (SEM) measurement was done to check the microstructures of SDC film and single cell. The parameters greatly affected the quality of SDC film and cell performance. The single cell with the optimum parameters exhibited an OCV of 0.82 V and a power density of 0.5 W/cm(2) at 600 degrees C. (C) 2008 Elsevier Ltd. All rights reserved.

关键词: thin films;electrochemical properties;microstructure;oxide fuel-cells;ysz electrolyte;thin-film;electrochemical;performance;electrophoretic deposition;reduced-temperature;cathode;anode

OXIDE METALLURGY-ITS PURPOSES AND PRACTICAL APPROACHES

Z. T. Ma and D. Janke(Institute of Iron and Steel Technology , 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 , null , null , null

Improvement of Ductility of Powder Metallurgy Titanium Alloys by Addition of Rare Earth Element

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 , null , null , null

SYNTHESIS OF NANO-ZnO PARTICLES FOR ALUMINUM METALLURGY AS INERT ANODE MATERIAL

A.A.A. Saleh , 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 , null , null

Experimental Study and Finite Element Polycrystal Model Simulation of the Cold Rolling Textures in a Powder Metallurgy Processed Pure Aluminum Plate

Liqing CHEN , Naoyuki Kanetake

材料科学技术（英文）

Ingot metallurgy (IM) aluminum has long been the subject and attracted the attention of many metallurgists and textural researchers of materials. Due to the introduction of large amounts of ex situ interfaces, however, the textures in powder metallurgy (PM) processed aluminum has been rarely reported. In this article, a pure aluminum plate was prepared $via$ PM route. The starting billet was first produced with uni-axially cold compaction and flat hot-extrusion and then followed by cold rolling processes. The hot-extruded and cold rolling deformation textures of the pure PM aluminum at 50%, 80% and 90% cold rolling reductions were studied by orientation distribution functions (ODFs) analysis. The finite element polycrystal model (FEPM) was finally utilized to simulate the cold rolling textural evolution at various stages of cold rolling. In FEPM simulation, the initial hot-extruded textures were taken into account as inputs. The results showed that typical β-fiber texture formed in pure PM aluminum with the cold rolling reduction increased till 80%, and there was not much change after excessive cold rolling deformation. Homogeneous slip is not the only deformation mode in PM processed pure aluminum plate at over 80% cold rolling reduction. The experimental results were qualitatively in good agreement with the simulated ones.

关键词: Texture , null , null , null , null

AP-FIM STUDY ON THE MICROSTRUCTURES OF TiAl INTERMETALLIC COMPOUNDS FXBRICATED BY INGOT METALLURGY AND CENTRIFUGAL SPRAY DEPOSITION

D.G. Ren , W.Z. Chen and X.S. Fan ( Laboratory of Atomic Imaging of Solids , Institute of Metal Research , The Chinese Academy of Sciences , Shenyang 110015 , China , College of Materials Science and Engineering , Fuzhou University , Fuzhou 350002 , China)

金属学报(英文版)

The microstructures of TiAl intermetallic compounds prepared by ingot metallurgy and centrifugal spray deposition (CSD) were compared by field ion microscopy and atom probe (AP-FIM). The samples used have nearly stoichiometric composition of TiAl but there is Mn addition for ingot metallurgy (IM) samples and Mn and Nb additions for CSD samples. The field ion image of TiAl showed two regions of ordered f.c.t crystal structure (γ-TiAl) and disordered α-Ti3Al, and the distribution of Ti and Al atoms in TiAl alloy showed a lamellar structure which was confirmed by AP profiles. AP profiles showed that the major constituent of IM TiAl alloy is γ-TiAl with some Ti-rich regions. The compositions of these Ti-rich regions are nearly Ti3Al and Ti2Al from the calculation of AP data. The sample of CSD has a similar microstructure as compared with IM sample. The effects of alloying elements (Mn and Nb) on the ordering extent ,their distribution, and their sites occupied in the lattice were explored for both TiAl alloys. But there are no obvious Ti3Al or Ti2Al phases as shown in IM sample. In addition, the distributions of Mn and Nb concentrations in the CSD sample have a characteristic of wave form.

关键词: intermetallic compound , null , null

Experimental and modeling investigation on SiC(p) distribution in powder metallurgy processed SiC(p)/2024 Al composites

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

SiC(p)/2024Al composites were fabricated through the powder metallurgy (PM) technique. The mixing process was modified by using a high ball to charge ratio (BCR), which resulted in improved homogeneity of the SiC(p) distribution, as well as enhanced tensile strengths of the as-pressed composites. A small particle size ratio of aluminum to SiC(p) (PSR) and extrusion also improved the uniformity of the SiC(p) distribution. The improvements by the three approaches were quantitatively analyzed using a critical volume fraction model. The model demonstrates that a small PSR and a large deformation ratio of aluminum particles were two essential factors of improving the homogeneity of the SiC(p). A homogeneity analysis using the Dirichlet Tessellation method provided an additional explanation for the model. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

关键词: Analytical modeling;Metal-matrix composites;Powder metallurgy;Reinforcement distribution;aluminum-matrix composites;particle-size ratio;mechanical-properties;microstructure;reinforcement

Fabrication and mechanical behavior of powder metallurgy processed in situ Nb/Al sheet metal-metal composites

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

A deformation processed 20 vol. % Nb/Al metal-matrix composite sheet was fabricated with powder metallurgical (PM) route, i.e. by hot extrusion and cold rolling techniques. A comparative study was made on the mechanical properties for this rolled in situ 20 vol.% Nb/Al metal-metal composites and a powder metallurgy processed pure Al sheet specimens at room and elevated temperatures up to 773 K. The results showed that the Nb particulates developed an elongated ribbon-like morphology after severe cold rolling reduction (CRR) and the mechanical properties of this kind material were largely influenced by the cold rolling reductions. The tensile test results at both room and elevated temperatures and strengthening mechanisms were also discussed. (C) 2003 Elsevier B.V. All rights reserved.

关键词: Nb/Al;extrusion;rolling;mechanical properties;metal-matrix;composites;ag-ni alloys;matrix composite;cold-drawn;wires;microstructure;deformation;strength;stability