S.C. Fan
,
B.K. Li
,
J.C. He
金属学报(英文版)
A mathematical model has been developed to analyze the flow patterns and subsurface trajectories of spherical shaped particles (alloy additions) in gas stirring ladles. First,a numerical method to solve fluid flow problems in conjunction with a curvilinear coordinate system is proposed. The internal boundary in flow field, which must be designated in the cylindrical polar coordinate system, can be avoided by using bodyfitted coordinate system (BFC). Consequently, computed flow of molten steel and paths of alloying additions are able to cross smoothly the geometric centerline of cylindrical vessel. Second, motion of particles is calculated in the three-dimensional coordinate system, the modification of parameters, such as the drag coefficient and density in the gas plume region, is examined. When the density of sphere is closer and closer to that of fluid, the path of motion is longer and longer. If the plug is moved off-centered to the half of radius, the path of sphere is prolonged, and the sphere may go through the geometric centerline of vessel, reach the deeper region. The immersed depths increase with increasing entry velocities.
关键词:
alloying addition
,
null
,
null
曾英
,
唐明林
,
殷辉安
应用化学
doi:10.3969/j.issn.1000-0518.2001.10.007
采用三元体系的溶解度数据,运用多元线性回归法拟合了Li 2CO3(a),Na 2CO3(b),Li 2B4O7(c)的单盐参数、溶解平衡常数及有关的混合离子作用参数.它们的值分别为:β(o)a=-1.235 5,β(1)a=-2.654 6,Cφa=-0.004 660 7,β(0)b=-3.030 6,β(1)b=-3.023 8,Cφb=-0.290 89,β(0)c=-0.293 04,β(1)c=2.155 6,Cφc=-0.004 256 0,θLi,Na=1.041 8,θB.C=-2.630 5,ψLi,Na,C=-0.063 91,ψLi,Na,B=0.493 56,ψLi,B,C=-0.478 42,ΨNa,B,c=0.306 16,In K(Li2CO 3)=-8.962 9,In K(Na2CO3@10H2O)=3.064 6,ln K(Li2B4O 7@3H2O)=-7.356 6,ln K(Na2B4O7@10H2O)=-7.477 8.以盐的溶解平衡常数为判据,运用Pitzer方程计算了四元体系Li+,Na+//CO2-3,B4O2-7-H2O 298 K时的溶解度,并采用等温溶解平衡法,对该体系298 K时溶解度进行了实验测定,同计算值相比,二者基本吻合.
关键词:
Li+
,
Na+//CO2-3
,
B4O2-7-H2O体系
,
溶解度
,
预测
Journal of Physics-Condensed Matter
Based on ab initio total energy calculations, Li, Na and Ag interstitials are found to be stable with at least a 1.56 eV energy barrier to transform to a zinc substitutional site in ZnO, whereas K interstitial has a relatively small energy barrier at 0.79 eV. The isolated dopant substitutional defects (LiZn, NaZn, KZn and AgZn) are found to be rather stable, with at least a 3.4 eV energy barrier to transform to an interstitial site. All of the dopant interstitials (Lii, Nai, Ki and Agi) are fast diffusers. The diffusion of Li interstitial is isotropic, whereas the diffusion of Na, K and Ag interstitials is highly anisotropic. Fundamental processes of the vacancy-assisted mechanisms are systematically investigated and specific values of the energy barriers are obtained.
关键词:
augmented-wave method
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:
Journal of Power Sources
The dissolution of NiO cathodes and the balance between the corrosion and contact ohmic resistance of current collector materials in molten carbonates are great obstacles to the commercialization of molten carbonate fuel cells (MCFC). Rare-earth element dysprosium was proposed to modify the NiO cathodes and to alloy nickel to explore its possible applications in MCFC. The measured solubility of NiO impregnated with 0.5-3 wt.% Dy in (0.62Li,0.38K)(2)CO3 at 650 degrees C in 60% CO-40% O-2 indicated that Dy addition increased noticeably the stability of NiO, while I wt.% Dy content produced better effectiveness. An investigation of the passive behavior of nickel and of Ni-Dy alloys containing 1-10 wt.% Dy in molten (Li,K)(2)CO3 with dynamic polarization measurements as well as X-ray diffraction and X-ray photoelectron spectroscopy indicated that the addition of Dy to nickel decreased its passive anodic current, and thus improved its corrosion resistance. The lithiation of NiO in the melt was a very significant reaction that could be promoted by the Dy additives to a certain extent, and increased the electrical conductivity of NiO. (c) 2007 Elsevier B.V. All rights reserved.
关键词:
molten carbonate fuel cell;Dy;Ni-Dy alloys;NiO solubility;electrochemical polarization;carbonate fuel-cell;electrochemical impedance;oxidation behavior;fe-20cr alloys;base alloys;cathodes;solubility;oxide;mcfc;licoo2
徐一斌
,
奚同庚
,
倪鹤林
,
段炼
,
李明华
,
蔡忠龙
,
费扬
材料研究学报
用DSC和激光热导仪分别测定了Li2B4O7(LBO)晶体350—970K范围内的比热和630—970K范围内不同主晶轴方向的导温系数.并由此得出了导热系数和声子平均自由程.
关键词:
Li_2B_4O_7晶体
,
specific heat
,
thermal diffusivity
,
thermal conductivity
,
phonon mean
李志友
,
黄伯云
,
汤春峰
,
刘志坚
,
曲选辉
功能材料
用柠檬酸盐溶胶-凝胶工艺制取了三种β-MxV2O5氧化物Li0.3V2O5、Na0.33 V2O5和K0.25V2O5;TG和DTA试验显示干凝胶焙烧过程中出现两个吸热峰,中间有一个放热峰;XRD分析表明高温处理时Li0.3 V2O5可氧化成LiV3O8和V2O5,而Na0.33V2O5和K0.25有较好的化学稳定性;模拟Li-B合金/LiCl-KCl/β-MxV2O5(或α-V2O5)热电池500℃放电试验表明β相阴极放电较α相平稳,但初始电压峰值略有降低,β-Li0.3V2O5相因具有较α-V2O5相更通畅的Li+快速扩散通道,且通道内没有Na+或K+大离子对Li+扩散的阻碍,放电最为平稳,有效比容量最高.
关键词:
溶胶-凝胶工艺
,
β相钒青石
,
热电池
,
阴极
High Temperature Materials and Processes
In order to decrease the solubility of NiO cathode of molten carbonate fuel cell (MCFC) and develop materials and coatings for separators in the cathode side of MCFC, dysprosium was introduced to modify nickel. In present paper, binary Ni-Dy alloys containing 1, 3 and 5 mass%Dy respectively were prepared. The alloys are two-phase composed of a nickel solid solution and an intermetallic phase Ni17Dy2. The oxidation behavior of the alloys at 923-1023K in air was evaluated by thermogravimetric tests coupled with some physical analysis techniques. The samples pre-oxidized at 923K for 100h were then immersed in molten (0.62Li,0.38K)(2)CO3 at 923K to examine the effect of Dy on the lithiation of NiO in the melt. The results indicated that the addition of dysprosium to nickel increased its oxidation rate, except for Ni-1Dy at 1023K. The scales formed on the alloys were composed of NiO with a trace of DY2O3. The lithiation of NiO in molten (Li,K)(2)CO3 could be favored by the addition of dysprosium. For comparison, binary Ni-Y alloys were also examined. The effect of yttrium on the air oxidation and molten (Li,K)(2)CO3 corrosion of nickel was similar to dysprosium, except that the Y-containing precipitates in Ni-Y alloys underwent very fast preferential corrosion while the Dy-containing intermetallic phases in Ni-Dy alloys not.
关键词:
molten carbonate fuel cell;Ni-Dy alloys;oxidation;molten carbonates;lithiation;fe-20cr alloys;behavior;600-800-degrees-c;coatings
High Temperature Materials and Processes
The ternary carbonate eutectic mixture of Li(2)CO(3), K(2)CO(3) and Na(2)CO(3) as a heat transfer and storage medium has excellent thermophysical properties, but with high viscidity as compared with some other inorganic salts such as chlorides and nitrates. The addition of chlorides or fluorides to molten carbonates may improve their fluidity, but possibly making the melt become more corrosive. In this study, the corrosion behavior of type 304, 310 and 316 stainless steels in an eutectic (Li,Na,K)(2)CO(3) melt with and without an eutectic mixture of NaCl and KCl at 973K in air have been examined. The experimental results indicated that 310 steel shows a much better corrosion resistance in molten carbonates than both 304 and 316 steels, due to the formation of a continuous LiCrO(2) scale. The addition of chlorides to carbonates melt accelerated the corrosion of the steels, especially 310 steel, producing scales with more porosity.
关键词:
Stainless steels;(Li,Na,K)(2)CO(3);(Na,K)Cl;molten salts corrosion;latent-heat-storage;potassium carbonates;lithium;sodium
刘颖
腐蚀与防护
为了探讨在熔融碳酸盐中加入氯化物对不锈钢的腐蚀作用的影响,采用浸泡方法研究了304和310不锈钢在添加了氯化物的700℃熔融(Li,Na,K)2CO3中的腐蚀行为.结果表明,两种不锈钢都遭受了严重腐蚀,不锈钢的快速腐蚀与循环的氯化-氧化反应有关.
关键词:
不锈钢
,
(Li,Na,K)2CO3-(Na,K)Cl
,
熔盐腐蚀
,
氯化-氧化
