H.Zhang
,
G.Wei
,
L.Zheng
,
L.Li
,
X.Y.Wang
,
A.Vaidya
材料科学技术（英文）
A good understanding of melting and resolidification of the substrate will help us to achieve better bonding. A numerical model is developed to investigate the solidification of the droplet, and melting and resolidification of the substrate. The molybdenum powder spraying onto three different substrates: a stainless steel, brass (70%Cu) and aluminum by atmospheric plasma spraying has been investigated. The maximum melting depth of the substrate has been measured and compared with the numerical prediction. Experimental results show that the material properties of the splat and substrate and melting temperature of the substrate play the important roles on substrate melting. A dimensionless parameter, temperature factor, has been proposed and served as an indicator for substrate melting.
关键词:
Thermal spraying
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null
,
null
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null
,
null
H.Zhang
,
S.B.Lin
,
L.Wu
,
J.C.Feng
金属学报(英文版)
Friction stir welding achieves the well in solid phase by locally introducing frictional heating and plastic flow arising from rotation of the welling tool, which results in changes in the local microstructure of magnesium alloy. The purpose in the paper is to study the microstructures of friction stir welled AZ31 magnesium alloy. Residual microstructures,including dynamic re-crystallization zone and nugget structures have been systematically investigated utilizing optical microscopy (OM), scanning electric microscopy (SEM),transmission electron microscopy (TEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and micro-hardness. AZ31 magnesium alloy has been successfully friction stir welded and exhibits the variations of microstructure including dynamically recrystaUized,equaxied grains in the well nugget. Residual hardness in the nugget was found slightly lower than the parent but not too obvious.
关键词:
friction stir welding
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null
,
null
FANG Zheng CHEN Xinmin(H.M.Chen) Central South University of Technology
,
Changsha
,
China FANG Zheng
,
Associate Professor
,
Department of Chemistry
,
Central South University of Technology
,
Changsha
,
China
金属学报(英文版)
By taking the effect of oxygen contents into account,a new set of formulae which represents the oxygen potentials of H_2O-H_2 and H_2O-H_2-inerts gas mixtures has been derived.Classi- cal representation is only a particular case of it.Some of the variables affecting equilibrium atmosphere when trace oxygen is present and optimum preparation of the gas mixtures to min- imize errors have been discussed.The reliability of some of previous equilibrium experiments under the oxygen potentials controlled by H_2O-H_2 or H_2O-H_2-inerts gas mixtures has also been criticized.
关键词:
gas equilibration method
,
null
,
null
,
null
Applied Physics Letters
ZnCoO:H nanocrystals are weak ferromagnetic at room temperature with a small coercivity and a small remanence, whereas ZnCoO nanocrystals are paramagnetic. The thermal irreversibility of zero-field cooling and field cooling magnetizations of ZnCoO:H nanocrystals corresponds to the existence of superparamagnetism due to the nanosize effect. X-ray photoelectron spectra show the incorporation of Co(2+) ions inside the ZnO lattice without changing the wurtzite structure. Our data suggest that hydrogen can induce ferromagnetism in ZnCoO and that ferromagnetic ZnCoO:H crystals with small particle size can show the superparamagnetism. (C) 2008 American Institute of Physics.
关键词:
magnetic semiconductors;zno;hydrogen;cobalt
王硕明
,
丁志军
,
于恒
,
张彩军
钢铁钒钛
研究了某H型钢厂采用半敞开方式浇注的H型钢腹板裂纹产生的原因.在该厂选取了26块有代表性裂纹的试样进行了细致的研究,研究认为:H型钢腹板裂纹主要是由钢中夹杂物因素造成,通过对钢中T[O]的研究发现,中间包T[O]量平均为94×10-6,铸坯中T[O]平均为60.8×10-6,同时对比1流铸坯和2流铸坯的T[O]量变化可以发现,中间包流场分布不合理.对该厂现有的中间包进行FLUENT模拟后发现,中间包稳流器矮坝较低,不能完全消除短路流,尤其在浇注后期,矮坝损耗殆尽,基本不起作用,短路流严重,应加以优化.
关键词:
H型钢
,
裂纹
,
夹杂物
,
数学模拟
徐峰
,
何彩红
,
徐勇
钢铁研究
简述了国内H型钢的发展现状,通过列举国内典型H型钢生产线,介绍分析了轧制H型钢的1-3-1、1-3和连轧三种工艺布置,以及目前轧制H型钢的X-X和X-H两种方法.根据目前国内生产状况,提出了H型钢技术改进的几项措施.
关键词:
H型钢
,
生产工艺
,
万能轧机
X.F.Rong and Z.Y.Qin College of Mechanical Engineering
,
Taiyuan University of Technology
,
Taiyuan 030024
,
China
金属学报(英文版)
In this paper, a deposition feature of a SiC:H films deposited by a RF sputtering system and a effect on the hardness of the films with various deposition conditions are investigated, and the effects of the silicon on a C:H are studied. It follows from the results that the properties of hardness can be changed with the depositing conditions. An increase of silane in the gas phase allows to deposit a SiC:H having tetrahedral structure. The sets of deposition conditions by which the different types of a SiC:H films can be deposited are obtained.
关键词:
a SiC:H film
,
null
,
null
