D. Jin
,
E. D. Dominik
,
R. V. Kolarik II
,
J. E. Ives and E. B. Damm (The Timken Company
,
1835 Dueber Avenue
,
S.W.
,
Canton
,
Ohio 44706-0932
,
U.S.A.)
金属学报(英文版)
An integrated mathematical model to simulate seamless tube rolling processes has been developed at The Timken Company. The model is capable of simulating the thermal, deformation and microstructure evolution in the piercing, elongating and reducing/sizing and the austenite decomposition in the mill annealing and cooling operations. Finite difference schemes are employed to model cooling, reducing/sizing and stretch reducing, and finite-element schemes are employed to simulate piercing and elongating. The model predicts the thermal history, deformation, rolling load, torque, recrystallization and grain growth in hot tube rolling, austenite decomposition in cooling or annealing, and the final structure-properties. In this paper mathematical models which are employed to describe the thermal, deformation and microstructure evolution along with the modeling results are presented. The developed "tube rolling mill in the computer" provides a powerful tool for engineers for product and process development, process control, process optimization and quality control.
关键词:
modeling
,
null
,
null
,
null
,
null
Physical Review B
We report that CaMn(7)O(12) is a new magnetic multiferroic material. The appearance of a ferroelectric polarization coinciding with the magnetic phase transition (similar to 90 K) suggests the presence of ferroelectricity induced by magnetism, further confirmed by its strong magnetoelectric response. With respect to other known magnetic multiferroics, CaMn(7)O(12) displays attractive multiferroic properties, such as a high ferroelectric critical temperature and large polarization. More importantly, these results open a new avenue to search for magnetic multiferroics in the catalog of doped oxides.
关键词:
manganese perovskite camn7o12;charge;polarization;transition
Rsc Advances
With the verification of the existence of the dissolution-electrodeposition mechanism during the electro-reduction of solid silica in molten CaCl2, the present study not only provides direct scientific support for the controllable electrolytic extraction of nanostructured silicon in molten salts but it also opens an avenue to a continuous silicon extraction process via the electro-deposition of dissolved silicates in molten CaCl2. In addition, the present study increases the general understanding of the versatile material extraction route via the electro-deoxidization process of solid oxides in molten salts, which also provokes reconsiderations on the electrochemistry of insulating compounds.
关键词:
3-phase interlines;electrochemical preparation;insulator compounds;calcium-chloride;sio2 pellets;nanowires;electroreduction;dioxide;mechanism;titanium
Applied Physics Letters
The magnetoelectric Tb-Fe/Pb(Zr(0.52)Ti(0.48))O(3) thin-film heterostructure was prepared by low energy cluster beam deposition. The microstructures, ferroelectric property, leakage current, and magnetization, as well as magnetoelectric effect were investigated for the heterostructure. It is shown that the thin-film heterostructure displays the well-defined microstructure with clear interface. The heterostructure not only exhibits good ferromagnetic and ferroelectric properties, but also possesses strong magnetoelectric effect. The present work provides an ideal avenue to prepare magnetoelectric composite films and facilitates their applications on the microelectromechanical system devices. (C) 2008 American Institute of Physics.
关键词:
composites
Journal of the American Ceramic Society
A novel nonequilibrium approach combining low-temperature reactive sputtering and excimer laser annealing was developed to resolve the opposing requirements on crystallization and minimization of dopant loss for creating heavily nitrogen-doped TiO(2) (TiON) thin film. By retaining nitrogen dopant concentration in the sputtered film, the laser annealing allowed exploration of new material chemistry not generally available to the conventional approaches. Compared with the traditional thermal annealing, the excimer laser annealing created TiON thin film samples with a higher nitrogen dopant concentration, better crystallization, higher visible light absorbance, and faster degradation effect on organic pollutants. The crystallization process from excimer laser annealing was carried out at room temperature with minimal damage to the substrate, thus applicable to plastic/organic substrates. This approach could be easily applied to other dopant/thin film/substrate systems, opening up an unexplored avenue for creating thin films with novel properties for a broad range of potential technological applications.
关键词:
visible-light;photocatalytic activity;optical-properties;tio2;dioxide;powders;oxidation;water
崔立治
,
袁子洲
,
张香云
,
冯雪磊
稀有金属材料与工程
利用铜模吸铸法制备(Cu0.46Zr0.44Al0.0sDy0.02)100-xFex (x=0.,3,5,7)非晶合金,利用X射线衍射仪(XRD)、同步热分析仪(DSC)、透射电镜(TEM)、万能试验机和扫描电镜(SEM)研究了Fe元素添加对Cu基非晶合金结构及力学性能的影响.结果表明:Fe元素的适量添加有利于改善Cu46Zr44Al8Dy2块体非晶合金的结构,当添加原子分数为1％和3％Fe时,合金为完全非晶结构,并且出现富Fe相和富Cu相两相分离.Fe元素的适量添加有利于提高Cu46Zr44Al8Dy2合金的强度和塑性,当添加3％Fe时,块体非晶合金的抗压强度σf和塑性εp分别达到1835MPa和0.5％.
关键词:
Cu基非晶合金
,
元素添加
,
相分离
,
力学性能
Nanotechnology
Single-crystalline spherical nearly monodisperse tellurium (Te) nanocrystals (NCs) with average diameters of 20 and 90 nm, respectively, have been fabricated for the first time by a facile solution sonochemistry process. The structural characterizations show that the as-synthesized Te NCs have pure hexagonal structure, as revealed by x-ray diffraction (XRD), selected-area electron diffraction (SAED), energy-dispersive x-ray (EDX) spectroscopy, and high-resolution transmission electron microscopy (HRTEM) methods. The size-dependent structural phase transition of Te NCs up to the high pressure of 20 GPa has been investigated in a diamond anvil cell using resistance measurement at room temperature, and compared with the behavior of bulk Te under identical conditions. The experimental results indicate that 20 nm Te NCs, 90 nm NCs, and bulk Te all undergo two phase transitions up to 20 GPa, their respective transition pressures being about 7.2 and 10.3 GPa, 5.9 and 8.8 GPa, and 4.0 and 6.8 GPa. This indicates that the phase transition pressures are higher for the smaller NCs. In this paper we discuss the size-dependent structural phase transitions, the sluggishness of the phase transition process, and the fluctuating properties of the phase transition products at high pressure. The present work might open an avenue to real-time detection of the dynamics of the phase transition in bulk and nanoscale materials at high pressure, and also could serve as a guide to tailoring the microscopic properties of materials.
关键词:
cdse nanocrystals;semiconductor nanocrystals;electrical-properties;growth-mechanism;nanorods;transformations;nanowires;nanotubes;nanostructures;superlattices
史汉桥
,
丁常方
,
孙宝岗
,
程雷
,
刘千
,
杨智勇
玻璃钢/复合材料
本文采用热熔法制备SW280玻璃布/苯并噁嗪预浸料,并对苯并噁嗪树脂工艺性、热失重性能,及复合材料动态热机械性能、高温力学性能保持率、阻燃性能等进行工艺试验和性能评价.结果表明,苯并噁嗪树脂软化点在41～42℃,最低黏度点为1835mPa·s,满足热熔法预浸料的制备要求;氮气氛围下起始分解温度280℃左右,800℃时残碳率可达61.3％.SW280玻璃布/苯并噁嗪复合材料力学性能优异,界面粘接良好,玻璃化转变温度为200℃,其200℃高温下的压缩强度、弯曲强度、弯曲模量和层剪强度保持率分别为90.6％、59.4％、83.2％和62.7％.SW280玻璃布/苯并噁嗪复合材料阻燃性能优异,无焰和有焰模式下最大烟密度均为0,氧指数＞58％,燃烧等级为V-1.
关键词:
苯并噁嗪树脂
,
热熔法预浸料
,
工艺性
,
力学性能
,
阻燃性能
