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INFLUENCES OF CASTING SPEED AND SEN DEPTH ON FLUID FLOW IN THE FUNNEL TYPE MOLD OF A THIN SLAB CASTER

B.W. Li , X.Y. Tian , E.G. Wang , J.C. He , null , null , null , null

In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based on structured body fitted coordinate grids. The CFD (computational fluid dynamics) package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid flow in thin slab caster. Two operational parameters, casting speed and SEN depth (submerged entry nozzle), are mainly considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.

关键词: continuous casting , null , null

Preparation of Li-B alloy and study of its microstructure and discharge characteristics

Zhijian LIU , Zhiyou LI , Wei DUAN , Xuanhui QU , Baiyun HUANG , Siqi ZHANG

材料科学技术（英文）

A LI-B alloy has been prepared using a pretreated amorphous B powder and pure Li ingot as starting materials by continually slow addition of B powder and intensified stirring in the process of melting. The microstructure and the discharge characteristic of the materials have been investigated. Results show that the problem of temperature control in synthesis would be modified by means of continual addition of B powder, the Li7B6 would be more finery distributed in the metal Li by means of intensified stirring. The discharge characteristic of the Li-B alloy using amorphous B as starting materials is almost the same with that of using crystalline B.

关键词:

代铬镀层--Ni-W、Ni-W-B非晶态合金镀层性能研究

朱立群 , 李卫平

电镀与涂饰 doi:10.3969/j.issn.1004-227X.2004.05.003

通过在浓硝酸、w=5% NaCl溶液、c＝1 mol/L H2SO4溶液中的浸渍试验,研究了不同基体上的Ni-W非晶态合金镀层的耐蚀性;通过测定在w=5% NaCl溶液及c=1 mol/L的HNO3溶液、H2SO4溶液、HCl溶液中的阳极极化曲线,研究了Ni-W非晶态合金镀层薄膜本身的耐蚀性;采用线性极化方法对Ni-W-B非晶态合金镀层在w=5% NaCl溶液、c＝1 mol/L H2SO4溶液及HNO3溶液中的腐蚀速度进行了测定,并测定了以上2种非晶态合金镀层的硬度与耐磨性.结果表明,非晶态的Ni-W、Ni-W-B镀层比晶态镀层的耐腐蚀性能要好,而Ni-W-B 非晶态合金镀层比Ni-W非晶态合金镀层的耐蚀性能又明显提高;经热处理后,Ni-W-B非晶态镀层的硬度值明显高于Ni-W非晶态镀层,耐磨性能都提高了1倍以上.Ni-W、Ni-W-B非晶态镀层极有望成为一种比较好的代铬镀层.

关键词: 代铬镀层 , 非晶态镀层 , Ni-W , Ni-W-B , 耐蚀性能

B2 precipitates and distribution of W in a Ti-47Al-2W-0.5Si alloy

Intermetallics

The precipitation behavior of B2 particles and the distribution of W in a Ti-47Al-2W-0.5Si alloy were investigated using high-spatial resolution analytical electron microscopy (AEM) and high-resolution electron microscopy (HREM). The ledges at the alpha(2)/gamma interfaces were found to be enriched in W and therefore the preferable nucleation sites for the B2 precipitates. In the B2 phase, as high as one third of Al is substituted by W in comparison with the composition of the 7 phase. The segregation of W to the alpha(2)/gamma and B2/gamma interfaces was also detected. These results provide explanations for the previous observations that additions of tungsten are effective in promoting the creep resistance of TiAl alloys. (C) 2002 Published by Elsevier Science Ltd.

关键词: titanium aluminides, based on TiAl;precipitates;phase interfaces;site;occupany;electron microscopy, transmission;analytical electron-microscope;gamma-titanium aluminides;orientation;relationship;creep deformation;tial alloy;atomic-scale;segregation;microstructure;interfaces;resistance

Li-B合金的制备及反应机制研究

许小静 , 段柏华 , 曲选辉 , 罗远辉

稀有金属材料与工程

通过对合成装置的温控、散热、搅拌桨叶片等进行有效改进,获得了300 g/炉的制备规模,制备出的合金性能均匀一致,其密度及抗拉强度分别为0.870 g/cm3,12.61 Mpa.同时,根据反应合成现象及XRD结果,分析了Li-B合金的反应机制及其动力学过程.

关键词: 热电池 , Li-B合金 , 阳极材料 , 制备 , 反应机制

热电池阳极Li-B合金放电前后的微观特征

刘志坚 , 段伟 , 黄英华 , 李志友 , 曲选辉

功能材料

使用扫描电子显微境对放电前后的Li-B合金的微观特征进行了观察,对影响Li-B合金放电稳定性的主要因素进行了分析.结果表明,轧制后的Li-B合金为塑性好的Li包裹脆性的LiB粒子,在520℃放电后Li-B合金与电解质界面依然完整,在大电流(200mA/cm)短时间(12min)放充电后,金属锂被LiB和电解质分割,表现在断口上金属锂为细丝状.

关键词: 热电池 , Li-B合金 , 阳极

急冷 Li_2O-B_2O_3-WO_3系统玻璃的制备及其性质

沈贤飞 , 干福熹

材料研究学报

用双辊急冷法把Li_2O-B_2O_3-WO_3系统的玻璃形成范围扩大了近二倍。IR 光谱和Raman光谱研究表明:少量WO_3取代B_2O_3时,W~(6+)离子以四配位存在并进入网络;引入多量WO_3时,[WO_4]增多并出现[WO_6],WO_3取代B_2O_3使玻璃稳定性下降,使导电率和介电常数增大。观察了30Li_2O·xWO_3·(70-x)B_2O_3玻璃在0.1N H_2SO_4非水性溶液中的电致色效应,发现着色速率与玻璃的电导率无关,而与WO_3含量成正比关系。

关键词: 双辊急冷 , glass structure , ionic conduction , electrochromic

热电池阳极材料Li-B合金的密度分析

刘志坚 , 曲选辉 , 李志友 , 黄伯云

中国有色金属学报

根据LiB化合物的六方结构模型，计算了热电池阳极材料Li-B合金随B含量变化的理论密度曲线。采用阿基米德方法分别测量了含24%(摩尔分数)B的Li-B合金反应完全并经冷挤压后的样品和未经第二次放热反应中间样品的密度，综合分析了以往不同研究者所测量的结果。结果表明，反应充分并消除合金中孔隙后合金的实验密度值与理论计算值一致，以往造成实验偏差的主要原因是样品中存在孔隙。中间样品的密度与Li-B元素混合计算密度一致，它支持在第一次反应和第二次反应之间B熔化在Li中的观点。

关键词: Li-B合金 , 阳极 , 热电池 , 密度