Young-Chan Kim
,
Chang-Seog Kang
,
Jae-Ik Cho
,
Chang-Yeol Jeong
,
Se-Weon Choi
,
Sung-Kil Hong
材料科学技术（英文）
Recently, demand for the lightweight alloy in electric/electronic housings has been greatly increased. However, among the lightweight alloys, aluminum alloy thin-walled die casting is problematic because it is quite difficult to achieve sufficient fluidity and feedability to fill the thin cavity as the wall thickness becomes less than 1 mm. Therefore, in this study, thin-walled die casting of aluminum (Al-Si-Cu alloy: ALDC 12) in size of notebook computer housing and thickness of 0.8 mm was investigated by solidification simulation (MAGMA soft) and actual casting experiment (Buhler Evolution B 53D). Three different types of gating design, finger, tangential and split type with 6 vertical runners, were simulated and the results showed that sound thin-walled die casting was possible with tangential and split type gating design because those gates allowed aluminum melt to flow into the thin cavity uniformly and split type gating system was preferable gating design comparing to tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. Also, the solidification simulation agreed well with the actual die-casting and the casting showed no casting defects and distortion.
关键词:
Aluminum casting alloy
,
null
,
null
Chang-Seog Kang
,
Jae-Ik Cho
,
Chang-Yeol Jeong
,
Se-Weon Choi
,
Young-Chan Kim
材料科学技术（英文）
Silicon-based aluminum casting alloys are known to be one of the most widely used alloy systems mainly due to their superior casting characteristics and unique combination of mechanical and physical properties. However, manufacturing of thin-walled aluminum die-casting components, less than 1.0 mm in thickness, is generally known to be very difficult task to achieve aluminum casting alloys with high fluidity. Therefore, in this study, the optimal die-casting conditions for producing 297 mm×210 mm×0.7 mm thin-walled aluminum component was examined experimentally by using 2 different gating systems, tangential and split type, and vent design. Furthermore, computational solidification simulation was also conducted. The results showed that split type gating system was preferable gating design than tangential type gating system at the point of view of soundness of casting and distortion generated after solidification. It was also found that proper vent design was one of the most important factors for producing thin-wall casting components because it was important for the fulfillment of the thin-wall cavity and the minimization of the casting distortion.
关键词:
Aluminum
,
null
,
null
,
null
PANG Dexing WANG Jingtang DING Bingzhe LI Zhixian Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
China WANG Jingtang
,
Professor
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The glass transition in amorphous semi-conducting Se has been studied by DSC thermal ana- lysis,infrared absorption spectra and positron annihilation measurements.The results show that the glas transition seems to be reasonably explained from the viewpoints of MDS model and valence alternation pair theory proposed by Mott,Kaster et al.,respectively.
关键词:
amorphous Se
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null
,
null
,
null
李晓龙
,
赵明
,
庄大明
,
巩前明
,
曹明杰
,
欧阳良琦
,
郭力
,
孙汝军
,
高泽栋
材料研究学报
doi:10.11901/1005.3093.2015.090
对球磨时间不同的Cu2Se、In2Se,和Ga2Se3混合粉末进行热压烧结制备CIGS靶材,发现在球磨时间较短时靶材出现分层,随着球磨时间延长分层缺陷消失.由此考察了粉末在球磨过程中发生的物理化学变化及其对分层的影响.结果表明:Cu2Se、Jn2Se3和Ga2Se3三种硒化物粉末在球磨过程中发生机械合金化反应形成黄铜矿相Cu(In,Ga)Se2(CIGS).随着球磨时间的延长,黄铜矿相结构CuInSe2(CIS)首先在Cu-Se二元化合物表面产生,并随着Ga原子的扩散逐步形成CIGS四元相.当球磨时间达到48 h时,粉末由黄铜矿相CIGS和少量Ga2Se3组成.由于Cu2-xSe与CIGS晶体结构相近,因此通过外延反应的方式有效促进了CIGS的合成.球磨过程中Cu-Se二元相的消失和CIGS相的形成有助于抑制烧结过程中分层缺陷的产生.
关键词:
无机非金属材料
,
铜铟镓硒
,
机械合金化
,
热压烧结
,
靶材
刘颖
,
许甫荣
,
曹钟斌
原子核物理评论
基于形变Woods-Saxon势下的推转壳模型对Se同位素进行Total-Routhian-Surface(TRS)计算.结果表明,原子核的形状随中子数变化很明显.对66,72,92,94Se基态TRS图进行分析,发现缺中子同位素和中子滴线附近核素均存在扁椭球和长椭球的形状共存.分别对72Se和94Se进行推转计算,长椭球和扁椭球形状在低推转频率下共存,由于g9/2闯入轨道的影响,随着推转频率的增加,扁椭球形变逐渐消失,长椭球形变带成为转晕带.
关键词:
形状共存
,
推转壳模型
,
Total Routhian Surface计算
Journal of Applied Physics
We report the magnetotransport properties of Fe(3)Se(4) nanowire arrays in anodic aluminum oxide (AAO) porous membrane. The temperature dependence of resistance of Fe(3)Se(4) nanowires at a zero field shows thermal activated behavior below 295 K. The exponential relationship in resistance is consistent with the model of strong localization with variable-range hopping (VRH) for a finite one-dimensional wire. Resistance versus magnetic field curves below 100 K show small positive magnetoresistance (MR). The field dependencies of log[R(H)/R(0)] explain the positive MR as the effect of magnetic field on the VRH conduction. (C) 2011 American Institute of Physics. [doi:10.1063/1.3544508]
关键词:
Philosophical Magazine Letters
In this work, we report the first observation of mechanically driven amorphous-nanocrystalline-amorphous phase transformations in Se during ball milling. Complete nanocrystallization of a glassy Se sample and complete amorphization of a nanocrystalline Se sample were realized by mechanical attrition, which provides a unique process for highlighting the intrinsic phase equilibrium between the glassy and nanocrystalline states.
关键词:
state;amorphization;transition;crystal;alloys;ge
Physical Review B
Microstructural evolution of an as-quenched amorphous Se sample during ball milling was investigated by use of x-ray diffraction, a differential scanning calorimeter, infrared and Raman spectroscopy, as well as x-ray photoemission spectroscopy. It was found that the as-quenched amorphous Se is crystallized completely into a nanocrystalline trigonal Se phase after milling for 30 min. Further milling of the as-milled nanocrystalline trigonal Se resulted in a transformation into another amorphous Se phase, which exhibits a lower crystallization temperature and a smaller crystallization enthalpy compared to those for the as-quenched amorphous Se according to thermal analysis. Infrared and Raman spectroscopy measurements revealed that the as-milled amorphous Se is mainly composed of Se-n polymeric chains that are fundamentally different from the as-quenched amorphous Se in which the Se-8 ring structure is predominant. However, despite the phase evolution and changes in molecular structure in Se, x-ray photoemission measurements indicated that no detectable changes in electronic properties (e.g. the density of valence states, the binding energies of core levels, and the characteristic energy loss functions) were observed among different states of Se samples. [S0163-1829(98)00417-2].
关键词:
induced nanocrystal formation;ball;transformation;alloys;ge;fe
李润
,
杨军强
,
孙雪杰
,
史克亮
,
吴王锁
环境化学
doi:10.7524/j.issn.0254-6108.2017.05.2016111302
硒是生物体中不可缺少的微量元素,具有双重生物效应.摄入量不足,会引发缺硒性疾病,而摄入量过多,又会引起硒中毒,其在人体中的日均摄入量安全范围为40-400 μg· d-1.近些年来,由于硒的污染日趋严重,硒在环境水体(包括淡水、海水、工业废水和生活污水)中的形态分布及其含量测定备受关注.本文在对硒的来源、物理化学性质、生物效应及环境行为总结的基础上,重点综述了环境水体中Se(Ⅳ)/Se(Ⅵ)的分离富集和分析测定方法,并就硒的形态分析进行了展望.
关键词:
Se(Ⅳ)/Se(Ⅵ)
,
环境水样
,
分离富集
,
分析测定
,
综述
