材料期刊网

Discovery and Research of High Tc Superconductor in the Institute of Physics, Academia Sinica

CHEN Liquan A special member of CCAST (World Laboratory) , Post Address: Institute of Physics , Academia Sinica , P.O. Box. 603. Beijing , China.

材料科学技术（英文）

关键词:

Molecular Dynamics Simulation of Gas Diffusion in B2O3 and SiC

Yajing YE , Litong ZHANG , Laifei CHENG , Yongdong XU

材料科学技术（英文）

Molecular dynamics simulation using a universal force field has been employed to determine the diffusion coefficients of O2 and Na2SO4 vapor into B2O3 and SiC from 700 K to 1273 K, respectively. Einstein diffusion was observed in a 250～300 ps simulation. The diffusion coefficient for the O2 range from about 9.279×10-9 cm2/s for B2O3 to 2.275×10-10 cm2/s for SiC at a loading of 32 molecules per simulation box, that for the Na2SO4 vapor range from about 9.888×10-7 cm2/s for B2O3 to 1.837×10-10 cm2/s for SiC at a loading of 8 molecules per simulation box. Environment properties of C/SiC composite will be increased via the B2O3 preventing the diffusion of O2 and Na2SO4 vapor into the pyrolytic interphase and carbon fibers.

关键词: Molecular dynamics , null , null , null

SHALLOW DONOR IMPURITY IN A QUANTUM BOX - EFFECTS OF IMAGE POTENTIAL

Solid State Communications

Considering the image potential, we calculate the binding energies of a shallow donor impurity placed on the centre of a quantum box using the variational approach. The results we have obtained show that there is a great difference of the effects of image potential between the cases including impurity ion image potential and including the image potentials of impurity ion and electron simultaneously. The results also show that the image potential is important, especially when the dimensions of quantum box become small.

关键词: well;gaas-ga1-xalxas;states

AU(603) and AU(675) Cluster Structures with (100) Facets Supported on MgO(010) Surfaces

Journal of Nanoscience and Nanotechnology

Structural changes of Au clusters respectively containing 603 and 675 atoms with their (100) facts supported on MgO(010) surfaces at 5 K have been investigated by molecular-dynamics simulations on the atomic interchange potentials of the metal/MgO interface, which parameters are from the Ab initio energies using Chen-Mobius inversion method. As the interaction time evolves, the structural changes accompanying with atom movements are determined by decomposing peaks of pair distribution functions (PDFs) according to the pair analysis (PA) technique, and local structure patterns are identified for the supported clusters. It is shown that there exist deformation processes of the two Au clusters to adjust their atom distances owing to atom misfits among the clusters and the MgO support. Concerning these supported clusters, the obtained results reveal how the cluster size and the interaction affect the structural changes in the interaction between the supported cluster and the MgO support.

关键词: Cluster;Molecular Dynamics;Computer Simulation;Surface;Nanostructure;molecular-dynamics;mgo(001) surface;au atoms;adsorption;dimers;mgo(100);models;dft

EFFECTS OF SPECIFIED BLANK SIZE ON BODY WRINKLING DURING HYDRODYNAMIC DEEP DRAWING OF TAPERED RECTANGULAR BOX

L. H. Lang , D. C. Kang , S. H. Zhang , Z. R. Wang , S. J. Yuan , K. B. Nielsen and J. Dancket 1) Department of Materials Engineering , Harbin Institute of Technology , Harbin 150001 , China 2) Aalberg University , Denmark

金属学报(英文版)

In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.

关键词: sheet metal forming , null , null

Effect of Variable Blank Holder Force on Rectangular Box Drawing Process of Hot-galvanized sheet Steel

Qunqiang FU

材料科学技术（英文）

At first, a series of finite element method (FEM) simulation tests were used to find the critical forming conditions of hot-galvanized sheet steel during the rectangular box drawing processing when constant blank holder forces were applied. According the test results, the reasonable alteration scope of initial variable blank holder force (VBHF) was as 1.9~2.3 T. Then, based on the test productions of blank holder force, 12 typical VBHF curves were applied to perform the simulation tests by the simulation software of DYNAFORM. The simulation test results showed that VBHF had great effects on drawing formability of hot-galvanized sheet steel during the rectangular box drawing. However, the different VBHF curves were applied to control the whole drawing and it would get great different effects. At the same tine, the VBHF had great effects on the maximum thick thinning ratio, but had little effect on the maximum thick incrassation ratio. So, reasonable application of the VBHF would greatly decrease the fractures. When the VBHF profile is taken as curve L, the best effect of drawing formability could be obtained. When curve I is used, contrary effect could be gotten. The other types of curves would cause effects between above two types of VBHF curves. Finally, the actual tests were applied to check the validity of the FEM simulation tests. The results show that the FEM simulation tests are good ways for predicting and optimizing the VBHF.

关键词: Drawing process , 变压边力 , 热镀锌钢板

Phase relations in the system La2O3-B2O3-P2O5

Journal of Alloys and Compounds

The subsolidus phase relations in the system La2O3-B2O3-P2O5 were investigated. The system can be divided into 12 three-phase regions. There are nine binary compounds and one ternary compound in this system. The ternary compound La7O6(BO3)(PO4)(2) has a monoclinic structure, space groups P2(1)/n, with lattice constants a = 7.0172 Angstrom, b = 17.9125 Angstrom, c = 12.6500 Angstrom, beta = 97.516 degrees, V = 1576.39 Angstrom(3), and Z = 4.

关键词: La2O3-B-3-B2O3-P2O5 system;phase relations;ternary compounds

p-Al2O3的水化特性研究

陈玮 , 姚长江 , 尹周澜 , 刘新红

耐火材料 doi:10.3969/j.issn.1001-1935.2008.04.009

分别对反应前后的p-Al2O3进行XRD及SEM分析,确定反应前后Al2O3的物相及显微结构变化;测定加入添加剂前后浆体温度与时间的关系,从而确定添加剂对p-Al2O3水化速度的影响;测定加入添加剂前后浆体的黏度变化,从而测定出添加剂对p-Al2O3水化过程的影响.结果表明:1)p-Al2O3属于无定形态;2)在没有添加剂的情况下,p-Al2O3的水化速率很快,同时释放出大量热量,水化产物主要是一水软铝石、三水铝石和拜耳石;3)加入碳酸钠及六偏磷酸钠的混合物为添加剂后,p-Al2O3的水化速率显著降低,释放出的热量显著降低,水化产物主要是一水软铝石.

关键词: p - 氧化铝 , 水化硬化 , 不定形耐火材料 , 结合剂

Subsolidus phase relations in the system BaO-B2O3-P2O5

Journal of Alloys and Compounds

The subsolidus phase relations in the system BaO-B2O3-P2O5 were determined. The system can be divided into 16 three-phase regions. There are nine binary compounds and three ternary compounds in this system. (C) 1997 Elsevier Science S.A.

关键词: ternary oxide system;alkaline earth borophosphates;crystal structure;crystal-structure;borate

Structure and Mechanical Properties of NiPNano Al2O3 Composite Coatings Synthesized by Electroless Plating

ZHOU Guanghong , DING Hongyan , ZHOU Fei , ZHANG Yue

钢铁研究学报(英文版)

NiPnano Al2O3 composite coatings were deposited by electroless plating, and their microstructures were observed by SEM (scanning electron microscope). The microhardness and the wear resistance of the NiPnano Al2O3 composite coatings were measured using microhardness tester and blockonring tribometer, respectively, and the comparison with those of NiP coatings or NiPmicro Al2O3 coating was given. The influences of aging temperature on their hardness and wear resistance were analyzed. The results showed that the nano Al2O3 particles were distributed uniformly in the NiPAl2O3 coatings. Among three kinds of NiP based coatings, the hardness and wear resistance of NiPnano Al2O3 coatings were largest, and the maximum values could be obtained at 400 ℃. This indicated that the precipitation of nano Al2O3 particles would improve the hardness and wear resistance of the NiP coatings.

关键词: composite coating;nano Al2O3;aging treatment;mechanical property