材料期刊网

EFFECTS OF OXIDES IN INVESTMENT MOLD ON SURFACE PROPERTIES OF TITANIUM CASTINGS

H.G. Wang , X.M. Qi , J. Tian , W.Q. Zha , G.S. Liang , Y. Y. Chen and J. Jia National Key Laboratory of Precision Hot Processing of Metals , Harbin Institute of Technology , Harbin 150001 , China

金属学报(英文版)

Effects of different facing oxides, including including yttria colloidal and powders (Y/Y), yttria stabilized zirconia colloidal and powders (ZY/ZY), zirconia colloidal and powders (Z/Z) and zirconia colloidal and zireonite powders (Z/ZS) on the qualities of investment castings are studied. The outward appearance, microstructures, and microhardness profiles of castings made of commercial pure titanium, Ti--Al--V and Ti--Al--Zr are investigated. Castings made by shells with yttria as face materials have the least contamination and by zirconite shells have the most contamination. Thermodynamic of metal-mold reactions is also taken into consideration.

关键词: titanium alloy , null , null

Relationship between the brittlement susceptibility and H permeation current for UNS g11180 steel in 5% NaCl solution with H2S

材料科学技术（英文）

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was, studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydrogen permeation technique. The results reveal different cracking mechanism and H permeation current (I-H) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 steel in 5% NaCl solution with H2S was evaluated by the permeation current (I-H, mu A), which depends on the concentration (c x 10(-6)) of H2S by the equation: I-H = 8.525 x c(0.7249). It is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

关键词: cracking

Relationship between the Brittlement Susceptibility and H Permeation Current for UNS G11180 Steel in 5% NaCl Solution with H_2S

Xueyuan ZHANG and Yuanlong DU(State Key Lab. for Corrosion and Protection , Institute of Corrosion and Protection of Metals , Chinese Academy of Sciences , Shenyang 110015 , China)

材料科学技术（英文）

Sulfide stress corrosion cracking (SSCC) behaviour of UNS G11180 steel in 5% NaCl solution with H2S was studied by slow strain rate tensile test (SSRT), SEM and electrochemical hydro gen permeation technique. The results reveal different cracking mechanism and H permeation current (IH) through UNS G11180 steel plate in different concentration of H2S solution. The susceptibility to SSCC of UNS G11180 Steel in 5% NaCl solution with H2S was evaluated by the permeation current(IH, μA), which depends on the concentration (c×10-6) of H2S by the equation:IH = 8.525 ×c0.7249. lt is proved that the electrochemical H permeation method is a practical way to assess the susceptibility to SSCC.

关键词:

Two-step magnetization in a spin-chain system on the triangular lattice: Wang-Landau simulation

Physical Review B

The Wang-Landau algorithm is used to study the thermodynamic and magnetic properties of triangular spin-chain system based on two-dimensional Ising model in order to understand the magnetic-order dynamics in Ca(3)Co(2)O(6) compound. The calculated results demonstrate that the equilibrium state of the rigid spins produces the two-step magnetization curve at low temperature even when the random-exchange term is considered. This work indicates that the four-step magnetization behavior observed experimentally must be due to the nonequilibrium magnetization.

关键词: calcium compounds;exchange interactions (electron);Ising model;magnetisation;thermodynamics;one-dimensional ca3co2o6;density-of-states;compound ca3co2o6;phase-diagram;proteins;crystal

Incoloy 800H/20g复合板材料焊接技术探讨

叶建林 , 杨永福 , 巨建辉 , 董斌

中国材料进展 doi:10.3969/j.issn.1674-3962.2006.01.008

研究Incoloy 800H/20g复合板焊接工艺,以解决以镍基合金复合板材为主体的设备在焊接过程中易产生裂纹、气孔及成分偏析等问题.焊接实验选择H1Cr16Ni21作为过渡填充金属,采用惰性气体保护焊和手工电弧焊2种形式焊接.实验结果表明,选择H1Cr16Ni21作为过渡填充金属,采用小电流、多道次焊接工艺,可得到质量良好的焊缝,焊缝宽度、焊缝余高、咬边及焊接错边均符合JB4730-94标准要求;力学性能优于20g耐热钢,焊缝成分与Incoloy800H接近.成功地解决了成分差异较大的2种材料焊接时易出现裂纹和气孔的问题.

关键词: Incoloy 800H/20g复合板 , 焊缝质量 , 焊接工艺

g-C(3)N(4) coated SrTiO(3) as an efficient photocatalyst for H(2) production in aqueous solution under visible light irradiation

International Journal of Hydrogen Energy

A highly active photocatalyst based on g-C(3)N(4) coated SrTiO(3) has been synthesized simply by decomposing urea in the presence of SrTiO(3) at 400 degrees C. The catalyst demonstrates a high H(2) production rate similar to 440 mu mol h(-1)/g catalyst in aqueous solution under visible light irradiation, which is much higher than conventional anion doped SrTiO(3) or physical mixtures of g-C(3)N(4) and SrTiO(3). The improved photocatalytic activity can be ascribed to the close interfacial connections between g-C(3)N(4) and SrTiO(3) where photo-generated electron and holes are effectively separated. The newly synthesized catalyst also exhibited a stable performance in the repeated experiments. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词: Carbon nitride;Photocatalyst;Visible light;SrTiO(3);tio2 nanotube photocatalyst;hydrogen-production;water;generation;oxynitride

Studies of the optical band positions and EPR g factors for Cu(H(2)O)(6)(2+) centers in Tutton salt crystals

Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy

The optical band positions and EPR g factors (i =x, y, z) of Cu(H(2)O)(6)(2+) clusters in pure Tutton salts M(2)Cu(SO(4))(2)center dot 6H(2)O (M= NH(4), Rb) are calculated from the complete diagonalization (of energy matrix) method based on the cluster approach. In the calculation, the superposition model with the structural data is used to obtain the crystal-field parameters. The calculated results are in reasonable agreement with the experimental values, suggesting that the complete diagonalization method and superposition model are effective in the studies of optical and EPR data. The g factors g(i) of Cu(H(2)O)(6)(2+) clusters in Cu(2+) doped isomorphous diamagnetic Tutton salts M(2)Zn(SO(4))(2)center dot 6H(2)O are also studied from the same method. It is found that the approximately tetragonally compressed Zn(H(2)O)(6)(2+) octahedra in the host crystals change to the approximately tetragonally elongated Cu(H(2)O)(6)(2+) octahedra in the impurity centers. The causes concerning the Jahn-Teller effect are discussed. It appears that in some cases the octahedral environment of an impurity M(1) in crystals differs from that of the replaced host ion, but is close to the one in the isomorphous pure crystals where M(1) is the host ion rather than the impurity ion. (C) 2011 Elsevier B.V. All rights reserved.

关键词: Electron paramagnetic resonance;Optical spectrum;Crystal- and;ligand-field theory;Tutton Salts;Cu(2+);atomic screening constants;gyromagnetic factor;scf functions;copper(ii);field;model;ions;spin

G-3合金在高含H2S/CO2环境中的腐蚀电化学行为

崔世华 , 李春福 , 荣金仿 , 任强

材料科学与工程学报

采用腐蚀电化学动电位扫描技术和腐蚀产物膜的SEM、EDS等微观分析手段,研究了G-3合金在高含H2S/CO2腐蚀环境中,CO2、pH值、Cl-等不同因素对镍基合金G-3腐蚀行为的影响.结果表明:Cl-不利于G-3钝化膜的形成,且使腐蚀加剧;CO2的加入促进了G-3的腐蚀,pH值的增加使G-3的自腐蚀电位出现较大负移.并影响了腐蚀产物膜的稳定性.

关键词: 镍基合金G-3 , H2S/CO2 , 腐蚀 , 腐蚀影响因素

Investigations of the g factors for the trigonal Ti(H2O)(6) (3+) clusters in frozen solution from two microscopic spin Hamiltonian methods

Journal of Physics and Chemistry of Solids

The spin Hamiltonian parameters (SH) (g factors g(vertical bar vertical bar) and g(perpendicular to)) for the trigonal [Ti(H2O)(6)](3+) clusters in the rapidly frozen solutions of Ti3+ are calculated from the complete diagonalization (of energy matrix) method (CDM, which is established in this paper) and the perturbation theory method (PTM). The two methods are based on the two-spin-orbit-parameter model (where both the contribution due to the spin-orbit (SO) coupling parameter of central 3d(n) ion and that of ligand are included) rather than the one-SO-parameter model in the conventional crystal-field theory (where only the contribution due to the SO coupling parameter of 3d(n) ion is considered). The calculated results from both methods are not only consistent with the observed values, but also close to each other. This suggests that both methods can be effective in the studies of SH parameters. (c) 2006 Elsevier Ltd. All rights reserved.

关键词: inorganic compounds;crystal fields;electron paramagnetic resonance;(EPR);electronic structure;atomic screening constants;superposition model;scf functions;crystal;parameters;ions;epr;titanium

镍基合金G3在高含H2S和CO2环境中的腐蚀行为

邓洪达 , 崔世华 , 李春福 , 曹献龙 , 兰伟

腐蚀与防护

采用高温高压模拟腐蚀试验、动电位扫描技术和X射线光电子能谱仪(XPS)等手段研究了镍基合金G3在高含H2S和CO2腐蚀环境中的腐蚀行为.结果表明,在高温高压(90℃,32 MPa,PH2s为3.4 MPa,体积分数10.49％,PCO2为3.3 MPa,体积分数为10.41％)的模拟气田采出液中,镍基合金G3发生了明显腐蚀,腐蚀产物由片状晶粒构成；在含50％H2S气田采出水中加入CO2促进了合金的腐蚀,当CO2的体积分数进一步提高到50％,合金点蚀敏感性下降；在50％H2S和50％ CO2环境中,Cl-提高了合金点蚀敏感性,同时高浓度Cl-破坏了合金钝化膜自修复能力,G3在该腐蚀环境中形成的钝化膜由Cr2S3,Cr2O3,FeS,Fe2O3,Ni(OH)2和MoO3等组成.随着使用环境条件的恶化,合金钝化膜遭到破坏,腐蚀加速.

关键词: 镍基合金G3 , H2S , CO2 , 腐蚀 , 钝化膜