材料期刊网

Potential Response Analysis of Exponentially Decaying Polarizing Current of Electrode and its Use in the Study of Stress Corrosion Cracking(SCC)of Stainless Steel

Yanliang HUANG Ming LU Chunan CAO Haichao LIN Ming LU Corrosion Science Laboratory , Institute of Corrosion and Protection of Metals , Academia Sinica , Shenyang , 110015 , China

材料科学技术（英文）

A study on the potential response of exponentially decaying polarizing current of electrode was car- ried out.The appearance of critical point of the potential-time response of exponentially decaying current was ensured from theoretical analysis,and this is the theoretical foundation of the critical point method for the measurement of corrosion current of metals.The comparison of the corrosion currents measured by the critical point and static methods for the system of 321 stainless steel in 0.5N HCI+0.5N NaCI solution at static state shows that the results agree very well.Finally.the tran- sient corrosion currents of 321 stainless steel in 0.5N HCI+0.5N NaCl solution at different strain level are listed.

关键词: exponentially decaying current , null , null

Fabrication of Porous Si₃N₄-Lu₂Si₂O₇ Composite Ceramics

Pengfei Zhang Litong Zhang Xiaowei Yin

材料科学技术（英文）

To improve the corrosion resistance of porous Si₃N₄ used in the high temperature environments, which contain water vapor and volatile species, porous Si₃N₄-Lu2Si₂O₇ composite ceramics were fabricated by a process of oxidation bonding and pressureless sintering in flowing N₂ atmosphere at the temperatures lower than 1550°C. The pores in ceramics were formed by removing the pore-forming agent (phenolic resin). SiO₂ derived by the oxidation of Si₃N₄ at 1250°C in air reacted with Lu₂O₃ at various sintering temperatures, leading to the formation of Lu₂Si₂O₇ with excellent oxidation and corrosion resistance. The phase composition, microstructure, and mechanical properties of the porous ceramics depended on the sintering temperatures. Si₃N₄-Lu2Si₂O₇ composite ceramics with the porosity of 52% and the pore size of 0.2μm were obtained by oxidation bonding at 1250°C for 1 h and pressureless sintering at 1550°C for 2 h using 4 wt pct Lu₂O₃ additive.

关键词: Porous ceramics , 氮化硅 , 焦硅酸镥 , 无压烧结

Lu-induced orthorhombic phase in polycrystalline La0.7Sr0.3MnO3

Physica B-Condensed Matter

Polycrystalline La0.5Lu0.2Sr0.3MnO3 samples prepared by thermal decomposition are investigated by means of electron diffraction and high-resolution transmission electron microscopy. Besides rhombohedral La0.7Sr0.3MnO3 phase (R-phase) and hexagonal LuMnO3 phase (H-phase) reported by Huang, unexpectedly, an orthorhombic lattice (O-phase) with space group Pnma is observed in the interior of R-phase grain. The lattice parameters of the orthorhombic unit cell are a(o) = 5.44 angstrom, b(o) = 7.65 angstrom and c(o) = 5.48 angstrom The formation of O-phase results from a(-)b(+)a(-) type orthorhombic distortion of MnO6 octahedra induced by partial substitution of Lu3+ for La3+. Meanwhile, based on image simulation of the interface between R and O-phases, the atomic bonding on the interface is particularly discussed. (c) 2005 Elsevier B.V. All rights reserved.

关键词: orthorhombic lattice;octahedral;substitution;atomic bonding;la0.7-xluxsr0.3mno3 perovskites;transport-properties;magnetoresistance;films

Corrosion Science Laboratory,Academia Sinica(CSL AS)

材料科学技术（英文）

关键词:

Characterisation of initial atmospheric corrosion carbon steels by field exposure and laboratory simulation

Corrosion Science

The early stages of the evolution of atmospheric corrosion of carbon steels exposed in both a laboratory simulated and a natural atmosphere environment in Shenyang have been observed by in situ scanning electron microscopy. In the case of laboratory cyclic wet-dry tests, even though the chloride content level is very low, filiform corrosion is initiated in the early stage. The filiform corrosion grows in random directions, forming a network of ridges. White nodules nucleate and grow on the ridges during continued corrosion and eventually connect with each other to form the initial corrosion scale. Pits were also found on the surface beneath corrosion products. In the case of a natural atmospheric environment, both filiform corrosion and other localized corrosion, such as pitting and inter-granular attack take place in the initial stage. It is obvious that there is variety of localized corrosion in the initial stage of atmospheric corrosion. (C) 2007 Elsevier Ltd. All rights reserved.

关键词: steel;atmospheric corrosion;initial stage;localized corrosion;in-situ;iron;electrolyte;thickness

Lu-Si-O体系在高温水蒸气环境中的腐蚀行为

洪智亮 , 成来飞 , 鲁琳静 , 张立同 , 王一光

无机材料学报 doi:10.3724/SP.J.1077.2010.00186

采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料. 以氧化物的摩尔比来表示此三种粉体, 分别为：Lu₂O₃·SiO₂、Lu₂O₃·2SiO₂和Lu₂O₃·2.26SiO₂. 在1400℃、50%H₂O-50%O₂静态常压气氛下, 研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能, 结合X射线衍射（XRD）、傅里叶红外光谱（FTIR）和扫描电镜能谱分析（SEMEDS）等分析手段, 揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理. 结果表明：三种原始粉体主要物相依次为：Lu₂SiO₅+Lu₂Si₂O₇、 Lu₂Si₂O₇+SiO₂和Lu₂Si₂O₇+SiO₂. 在水蒸气作用下, Lu₂SiO₅相与Al₂O₃反应生成新相Lu₃Al₅O₁₂, 而Lu₂Si₂O₇相并未受到水蒸气的作用而发生任何反应, 表现出优异的化学稳定性.

关键词: Lu₂SiO₅ , Lu₂Si₂O₇ , environmental barrier coating (EBC) , water vapor corrosion

Lu-Si-O体系在高温水蒸气环境中的腐蚀行为

洪智亮 , 成来飞 , 鲁琳静 , 张立同 , 王一光

无机材料学报 doi:10.3724/SP.J.1077.2010.00186

采用溶胶-凝胶法制得三种镥硅酸盐体系粉体材料.以氧化物的摩尔比来表示此三种粉体,分别为:Lu_2O_3·SiO_2、Lu_2O_3·2SiO_2和Lu_2O_3·2.26SiO_2.在1400℃、50%H_2O-50%O_2静态常压气氛下,研究了它们的耐水蒸气腐蚀性能.以单位面积重量变化率表征材料的耐水蒸气腐蚀性能,结合X射线衍射(XRD)、傅里叶红外光谱(FTIR)和扫描电镜能谱分析(SEM-EDS)等分析手段,揭示了镥硅酸盐体系在高温水蒸气环境中的腐蚀机制和反应机理.结果表明:三种原始粉体主要物相依次为:Lu_2SiO_5+Lu_2Si_2O_7、Lu_2Si_2O_7+SiO_2和Lu_2Si_2o_7+SiO_2.在水蒸气作用下,Lu_2SiO_5相与Al_2O_3反应生成新相Lu_3Al_5O_(12)而Lu_2Si_2O_7相并未受到水蒸气的作用而发生任何反应,表现出优异的化学稳定性.

关键词: Lu_2SiO_5 , Lu_2Si_2O_7 , 环境障碍涂层 , 水蒸气腐蚀

Effects of A-site doping on microstructure and phase separation of La0.5RE0.2Sr0.3MnO3 (RE=Eu, Ho, Yb, Lu)

Materials Letters

Phase separation and microstructure of La0.7Sr0.3MnO3 doped with rare earth elements (Eu, Ho, Yb and Lu) are studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Composition and diffraction analyses demonstrate that the ionic radius of doping element plays an important role in the crystalline structure and the lattice constants of the secondary phase. When La 3 is replaced partly by Eu3+ or Ho3+, orthorhombic perovskite structure with space group Pnma is formed due to the distortion Of MnO6 octahedra. Different from the phenomenon observed by Huang et al., however, the hexagonal non-perovskite structure (YbMnO3 and LuMnO3) has appeared when La3+ and Sr2+ are substituted completely by Lu or Yb (c) 2005 Elsevier B.V. All rights reserved.

关键词: ionic radius;crystalline structure;lattice constants;orthorhombic;perovskite;hexagonal non-perovskite;magnetoresistance;perovskites;films

Lu2O3和Lu2O3∶Eu3+单分散球形粉体合成及其荧光性能研究

马畅 , 李晓东 , 董宇 , 刘绍宏 , 朱琦 , 李继光 , 霍地 , 孙旭东

中国稀土学报 doi:10.11785/S1000-4343.20130411

以Lu(NO3)3和尿素为原料,采用均相沉淀法合成镥盐前驱体,研究Lu3+浓度、尿素/Lu3+摩尔比R对前驱体形貌的影响.结果表明,在反应温度为95℃时,低Lu3+浓度有利于单分散球形粉体的合成,并且适当的调整R值可将单分散球形颗粒尺寸控制在180 ～ 270 nm之间.在此基础之上,研究Eu3+掺杂Lu2O3单分散球形荧光粉体的合成,探讨了Eu3+的掺杂量(1％,3％,5％,7％,9％(原子分数))及煅烧温度(600～ 1200℃)对颗粒形貌及其荧光性能的影响.结果表明,Eu3+的掺杂使所得(Lu,Eu)盐前驱体颗粒尺寸远小于单纯的Lu盐前驱体,且Eu含量对荧光粉的荧光强度有着显著的影响,荧光淬灭浓度为5％.在考察的煅烧温度范围内,荧光粉的荧光强度随煅烧温度的提升而增强.

关键词: Lu2O3 , Eu3+ , 均相沉淀 , 单分散球形 , 前驱体 , 荧光性能 , 稀土

TEMPERATURE-DEPENDENCE OF THE MAGNETIC-PROPERTIES OF THE RARE-EARTH TRANSITION-METAL INTERMETALLIC LU2FE14C

Journal of Magnetism and Magnetic Materials

Magnetization curves of the ternary tetragonal compound Lu2Fe14C were measured in an extracting-sample magnetometer in the temperature range from 1.5 to 300 K. The temperature dependence of the magnetic properties of Lu2Fe14C is discussed.

关键词: anisotropy