材料期刊网

采用TOPS-99和Cyanex 272钠盐从镍红土矿细菌浸出液中萃取锌、锰、钴和镍

R.K.MISHRA , P.C.ROUT , K.SARANGI , K.C.NATHSARMA

中国有色金属学报(英文版) doi:10.1016/S1003-6326(16)64119-5

在煤油中采用TOPS-99和Cyanex 272钠盐从镍红土矿细菌浸出液中提取与分离锌、锰、钴和镍.采用沉淀法去除不需要的金属离子,使用溶剂萃取提取/分离锌、锰、钴和镍.生物浸出铬铁矿表土样品得到的镍红土矿浸出液中含有3.72 g/L Fe,2.08 g/L Al,0.44 g/L Ni,0.02 g/L Co,0.13 g/LMn,0.14 g/L Zn和0.22 g/L Cr.在pH4时采用CaCO3沉积去除100％ Fe,96.98％ Al和70.42％ Cr,随后在pH 5.4时采用50％氨沉积,溶液中剩有Al和Cr.沉积后,采用0.1 mol/L TOPS-99从无铁、铝和铬的浸出液中提取锌,随后采用0.04 mol/L NaTOPS-99提取锰.锌和锰的产率分别是97.77％和95.63％.提取锰后,再采用0.0125 mol/L NaCyanex 272从浸取液去除钴,最后采用0.12 mol/L NaTOPS-99提取镍,其产率达99.84％.采用稀硫酸去除浸出液中的有机相.

关键词: 镍红土矿 , 锰 , 镍 , TOPS-99 , Cyanex 272

Secondary M6C precipitation in K40S cobalt-base alloy

Materials Letters

Secondary M,C precipitation was investigated in K40S cobalt-base alloy after 100 h aging at 950 degreesC. The results showed that it was closely related to the tungsten-rich zones inherited from the as-cast condition and the degeneration of the primary M7C3 carbide. A direct element reaction, 6M + C --> M6C, in which C comes from the decomposition of the M7C3 carbides, is suggested as the mechanism of secondary M6C precipitation in K40S alloy. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词: M6C precipitation;aging;M7C3 carbide;superalloy

裂纹顶端位错的运动和小范围屈服的K_(Ⅱc)

龙期威 , 高桦

金属学报

本文从裂纹顶端位错运动的简化模型估计形成塑性区所消耗的功;从而计算临界裂纹扩展力。由于Ⅰ型加载和Ⅱ型加载的应力状态有所不同,裂纹顶端塑性功耗也会不一样。基于上述思想,考虑了小范围屈服的K_(Ⅰc)和K_(Ⅱc)的关系,得出K(Ⅱc)>K(Ⅰc)的结论,符合实验结果;并就K(Ⅱc)/K(Ⅰc)的比值与材料性能和温度的关系作了讨论。

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Zn-5%Al合金超塑性的m-C-δ(或m-k-δ)关系

刘勤 , 夏锄 , 刘晓东

金属学报

在170,190,210,230,250℃的温度下,采用3.7×10~2,7.4×10~2和1.1×10~(-1)min(-1)的应变速率(平均)对Zn-5%Al共晶合金的m-C-δ(或m-k-δ)关系曲线(简称m-δ关系曲线)进行了测定.所有的曲线均随应变的δ增加而快速上升.俟达到某一定的应变量(极限应变量δ1)后。开始缓慢下降并保持平稳直至断裂.Zn-5%A1共晶合金的m-δ关系曲线不存在k_(?)=k_I(k_(I 1),k_(I 2),k_(I 3),……)=k_F(或C_0=C_I(C_(I 1),C_(I 2),C_(I 3),……)=C_F=1)的简单情况.可应用m-δ方程式[4,5]对曲线上各点C值(包括所有的C_I和C_F值)进行计算.C值随δ值的增加成近似的直线上升.直线的斜率在极限应变(δ1)处突然减小.

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Prediction and improvement of mechanical properties of corrosion resistant superalloy K44 with adjusting minor additions C, B and Hf

Materials Transactions

The neural network (NN) method is applied to predict the influence of minor additions C, B and Won mechanical properties of cast superalloy K44 with heat treatment parameters considered. Furthermore, the influence of minor additions C B and Hf on phase stability is estimated using d-electrons theory. The results from these two methods indicate that decreasing C content, increasing B content and doping 0.2-0.3 mass% Hf can balance the desired mechanical properties and phase stability in K44 alloy, which also is confirmed experimentally through the relation between mechanical properties and phase stability of base/modified K44 alloys.

关键词: superalloy K44;neural network;d-electrons theory;mechanical;properties;phase stability;bayesian neural-network;nickel-base superalloys;creep-rupture life;behavior;phase

Cyclic oxidation behavior of glass-ceramic composite coatings on superalloy K38G at 1100 degrees C

Thin Solid Films

The SiO(2)-Al(2)O(3)-ZrO(2)-CaO-ZnO glass-ceramic composite coatings (GC), nanocrystalline NiCoCrAlY coating, and their combinations (bi-layer GC/NiCoCrAlY) were prepared on K38G specimens. The thicknesses of the glass-ceramic coatings and the NiCoCrAlY coatings were about 10 mu m and 20 mu m, respectively. Cyclic oxidation tests were carried out at 1100 degrees C for 120 cycles. Microstructures of the specimens before and after oxidation tests were characterized by SEM, EDS and XRD. The glass-ceramic coatings with or without a NiCoCrAlY intermediate layer improved the isothermal and cyclic oxidation resistance of the Ni-base superalloy K38G at 1100 degrees C, and performed better than the NiCoCrAlY coatings. An alumina layer formed at the glass/metal interfaces of the specimens coated by the glass-ceramic coatings with or without a NiCoCrAlY intermediate layer. The NiCoCrAlY intermediate layer was beneficial to the cyclic oxidation resistance of the glass-ceramic coatings. (C) 2011 Elsevier B.V. All rights reserved.

关键词: Glass-ceramic coating;NiCoCrAlY;Cyclic oxidation;Magnetron sputtering;resistance;microstructure;scales

Ni在熔融(Li,K)2C03中的腐蚀行为

王文 , 曾潮流 , 吴维

腐蚀科学与防护技术 doi:10.3969/j.issn.1002-6495.1999.06.006

采用电化学阻抗谱技术研究了Ni在650 C熔融(Li,K)2CO3中的腐蚀行为.在自腐蚀电位下,Ni的腐蚀电化学阻抗谱呈典型的扩散控制特征,表面形成疏松的氧化膜,腐蚀速度较快.提出了相应的等效电路,求得相关电化学参数,

关键词: Ni熔融碳酸盐电化学阻抗谱熔盐热腐蚀

K2SiO3/C颗粒催化大豆油酯交换制备生物柴油

王建勋 , 陈洸艟 , 陈锦章

催化学报 doi:10.1016/S1872-2067(10)60265-3

采用浸渍法将钾水玻璃负载于碳颗粒(粒径1～3.5 mm)上,经120℃烘干后制得K2SiO3/C催化剂.以X射线衍射、扫瞄电镜-能量色散X射线与Hammett指示剂等方法对样品进行了表征.以K2SiO3/C为催化剂,大豆油为原料,进行酯交换反应制备生物柴油,考察了催化剂用量、醇/油摩尔比、反应时间(微波与传统加热)等因素对大豆油酯交换率的影响.当醇/油摩尔比30∶1,催化剂用量24 wt％时,传统加热反应于2.5 h达到96.5％酯交换率,而相同条件下微波加热反应于1.5h达到96.7％酯交换率.

关键词: 生物柴油 , 固体催化剂 , 钾水玻璃 , 碳颗粒 , 微波吸收

K3C60晶体中钾离子的平衡位置

刘红 , 陈宗璋 , 彭景翠 , 陈小华 , 白晓军

无机材料学报 doi:10.3321/j.issn:1000-324X.2000.03.004

分析八面体空隙中心碱金属的相互作用势能, 研究碱金属沿[111]、[110]和[100]三个不同方向移动时, 势能的变化情况, 结果表明, 对于K3C60晶体, K+离子在三个不同方向上都存在非中心平衡位置, 而且在三个不同方向上, 非中心平衡位置相对中心的偏移量不同, 在[111]轴上为0.98, 在[110]轴方向上为0.78, 在[100]方向上为0.56, 在[111]轴方向的非中心的势能是最小值, 为-508.59meV.通过对计算结果的分析, 认为非中心平衡位置的出现应归因于短程相互作用, 其中与C60的相互作用是最主要的, 其势能最低点对应的位置不在中心;三个不同方向的非中心平衡位置偏离中心距离不同, 是因为与之对应晶面上的C60面密度不同.

关键词: K3C60晶体 , 非中心格点 , 八面体对称性 , Lennard-Jones势 , 晶面

一种改进的C-V方法对向列相液晶弹性常数k11、k33测量的理论研究

孔祥建 , 荆海 , 黄霞 , 廖燕平 , 刘金娥

液晶与显示 doi:10.3969/j.issn.1007-2780.2007.05.017

提出了一种更为准确的测量向列相液晶展曲、弯曲弹性常数的C-V方法.以正性液晶材料为例,当沿面排列的液晶分子预倾角不为零时,阈值电压值不易确定, k11的确定必定存在误差,而以前报道并未考虑到此问题.文章针对此问题给出了在强锚定条件下,预倾角不为零时C-V的关系式,并提出了通过曲线拟合来同时确定弹性常数k11、k33的方法.此方法对弹性常数的测量更为准确,液晶盒的制作要求降低,且测试简单、易操作.

关键词: 向列相液晶 , 电容-电压 , 弹性常数 , 预倾角 , 曲线拟合