M. Emamy
材料科学技术（英）
Oxide films are incorporated into melts by an entrainment process, and are expected to be present in most
metals, but particularly cast Al alloys. The oxides are necessarily present as folded-over double films (bifilms)
that are effectively cracks. Their effect on the electrochemical behaviour of cast Al-5Zn-0.02In sacrificial
anodes was studied in 3 wt pct sodium chloride solution using the NACE e±ciency evaluation. Three methods
were employed to entrain progressive amounts of oxide in the alloy, including the addition of Al-Zn-In maching
chips to the charge, increasing the pouring height, and agitating the melt. The introduction of oxide bifilms
in the cast alloy resulted in the deterioration of the electrochemical properties of the sacrificial anodes, such
as current capacity and anode e±ciency, and introduced increasing variability in these properties. The results
suggest that corrosion behaviour is strongly related to the presence of bifilms suspended in the liquid alloy
because bifilms provide crack paths allowing the corrodant to penetrate deeply into the metal matrix, and
simultaneously provide localized galvanic cells because of the precipitation of Fe rich intermetallic compounds
on their outer surfaces.
关键词:
Aluminium
,
Sacrificial anode
,
Efficiency
,
Entrainment
,
Bifilm
邱闽旺
,
涂朝阳
,
李坚富
,
黄奕川
,
汪爱栋
,
唐鼎元
,
王元康
量子电子学报
doi:10.3969/j.issn.1007-5461.2001.04.012
本文报道了我所生长的掺钕钨酸钾钆(KGW)晶体的脉冲激光特性.当用氙闪光灯泵浦时,尺寸为φ3.4 mm×24 mm的KGW激光棒,最大激光输出为每个脉冲358.4mJ,总效率为1.7%,斜率效率为3.3%,波长为1.067μm.实验证明,KGW是一种很有前途的小型激光器工作物质.
关键词:
掺钕钨酸钾钆(KGW)晶体
,
1.067 μm激光
宋福展
,
刘金勇
,
孟献丰
,
沈湘黔
,
向军
无机材料学报
doi:10.3724/SP.J.1077.2009.00721
以柠檬酸和金属盐为原料,采用有机凝胶先驱体转化法制备了M型锶铁氧体(SrFe12O19)中空纤维.通过FTIR、TG/DSC、XRD、SEM和VSM等技术对所得纤维进行了表征.结果表明,凝胶的可纺性与其化学组成和pH值有关,当柠檬酸与金属离子的摩尔比为1.5:1.0,pH=4.2左右时,凝胶的可纺性最好.经1100℃焙烧后,制备的M型锶铁氧体中空纤维具有较大的长径比,直径可小于1μm,中空孔径约为纤维直径的一半,组成纤维的晶粒形貌为六角片状,晶粒尺寸为236nm,在室温下的饱和磁化强度为53.5A·m2/kg,矫顽力为386.96kA/m.纤维显示出一定的形状各向异性,当定向排列的纤维平行和垂直磁场时,矫顽力分别为391.66和358.72kA/m.
关键词:
有机凝胶先驱体转化法
,
M-Sr铁氧体
,
中空纤维
,
可纺性
,
磁性能
林成新
,
葛艳玲
,
谷南驹
,
刘庆锁
钢铁研究学报
用透射电镜和高分辨率电镜研究了Fe17Mn5Si10Cr5Ni合金的应力诱发εM形态.生长初期εM为厚约20 nm的薄片,它在长度方向上是不连续的,间断区为各生长单元的前沿区.生长初期的εM薄片在交叉时可利用本身的间断区而相互贯穿,且不留下交互作用痕迹,由εM薄片合并成宽大的εM.这种结构特点决定了宽大的εM薄片交互作用的复杂性.
关键词:
马氏体相变
,
应力诱发
,
间断区
,
交互作用
刘勤
,
周善佑
材料研究学报
超塑性m-δ关系曲线可以分为m_L=m_(max)和m_L=m_(min)两大类型。均可由下面的C.L.(刘勤)m-σ方程表示:σ(%)=〔cε~(m-m_0)-1〕×100当σ=σ_0=0时,m=m_0≠0,C=C_0=κ_0/κ_0=1。当σ=σ_1(σ_(11),σ_(12),σ_(13),…,)时,m=m_1(m_(11),m_(12),m_(13),…),C=C_1(C_(11),C_(12),C_(13),…)=κ_1(κ_(11),κ_(12),κ_(13),…)/κ_0,当σ=σ_F时,m=m_F,C=C_F=κ_F/κ_0。对C 值进行“规划”,得到的C_1~(σ_O-σ_L)-(m_L=m_(max)),C_2~(σ_F-σ_L)-(m_L=m_(min)),C_3~(m_0-m_L)-(m_L=m_(max)和C_4~(m_F-m_L)-(m_L=m_(min))四种类型的“规划”方程分别对m_L=m_(max)和m_L=m_(min)型m-σ曲线适用。若m-σ曲线属简单的下降式,C 及其“规划”值均可近似地取1。否则,C-σ关系是应加以研究的问题。m 和k 值对σ值的效应可以分为动态(直接)和静态(间接)两种。最后的σ值是两种效应的综合结果。(注:m 和κ值见基本方程σ=κε~m)
关键词:
宋福展
,
沈湘黔
,
向军
,
孟献丰
稀有金属材料与工程
以柠檬酸、乳酸和金属硝酸盐为原料,采用有机凝胶先驱体转化法制备了中空M型(BaFe12O19)纤维.通过FTIR、TG/DSC、XRD、SEM和VSM等技术对所得纤维进行了表征,并初步探讨了中空纤维的形成机制.结果表明,凝胶的可纺性与其组成和pH值有关,在pH值约等于4.5时,可纺性最好.纤维直径可小于1 μm,长径比可达8×105,组成纤维的晶粒尺寸大都在数十个纳米.中空BaM纤维在室温下的饱和磁化强度为22.5 Am2、Kg,矫顽力为300 kA/m.
关键词:
有机凝胶先驱体转化法
,
Ba铁氧体
,
中空纤维
,
可纺性
,
磁性能
刘颖
,
王敬平
,
胡敏
,
张密林
,
夏天
应用化学
doi:10.3969/j.issn.1000-0518.2007.10.019
采用Sol-Gel工艺,于850 ℃煅烧制备了单磁畴M型六角钡铁氧体(BaFe12O19)微粉. 运用X射线衍射仪、扫描电子显微镜和振动样品磁强计表征了产物的结构、形貌和磁性. 研究了煅烧温度和煅烧时间对产物的结构、磁性和形貌的影响. 结果显示,高的升温速率有利于片状产物的形成. 随煅烧时间的延长和烧结温度的升高,合成的M型六角钡铁氧体(BaFe12O19)的结晶更完美,粒子尺寸增大,晶粒更加均匀. 由于样品粒子为单磁畴颗粒,故引起样品的比饱和磁化强度和矫顽力均随着烧结温度的升高,烧结时间的延长而增大. 850 ℃煅烧4 h时,样品的比饱和磁化强度为53 A·m2/kg,矫顽力为277.6×103 A/m. 1 000 ℃煅烧4 h时,样品的比饱和磁化强度增加到59 A·m2/kg,矫顽力为353.3×103 A/m. 850 ℃煅烧,随时间从2 h延长到6 h,比饱和磁化强度从48 A·m2/kg增加到56 A·m2/kg,矫顽力也从211.5×103 A/m增加到357.1×103 A/m.
关键词:
Sol-Gel法
,
钡铁氧体
,
单磁畴
,
磁性
Journal of Magnetism and Magnetic Materials
Phase constitution and magnetic properties of Nd10Fe76B4M10 and Nd10Fe76B2M12 (M = Fe,Ti,V,Cr, Mn,Co and Al) alloys prepared by mechanical alloying and subsequent annealing have been systematically studied. It is found that the components of phases in the alloys critically depend on the additive transition metals M. In all the alloys, only the addition of Ti give significant enhancement to the permanent-magnetic properties. The increase of the Curie temperature in the Ti-doped alloys with an excessively low B content implies that part of the Ti atoms may occupy crystalline sites other than the Fe sites. In all the M additive alloys, with increasing content of the additive elements, the quantity of 1:7 phase increases and that of Nd2Fe14B-type phase decreases, (C) 2000 Elsevier Science B.V. All rights reserved.
关键词:
phase constitution;structure;magnetic properties;alloys;mechanical;alloying;nd;coercivity
