Author J.H. Lee 1)
,
K.B. Yoon2)
,
Y.J. Kim3)and U.B. Baek4) 1) Engineering Research Department
,
Korea Institute of Nuclear Safety
,
P.O. Box 114
,
Yoosung
,
Taejon 305600
,
Korea2) Department of Mechanical Engineering
,
Chung Ang University
,
221 Huksuk
,
Dongjak
,
Seoul 156756
,
Korea3) Department of Mechanical Engineering
,
Sungkyunkwan University
,
300 Chunchun
,
Jangan
,
Suwon 440746
,
Korea4) Failure Prevention Research Center
,
Korea Research Institute of Standards and Science
,
P.O. Box 102
,
Yoosung
,
Taejon 305600
,
KoreaManuscript received 18 October 1998
金属学报(英文版)
Most of the assessment equations for Ct which is a wellknown fracture parameter characterizing high temperature crack growth rates, have limited applicability to constant load conditions after sudden loading. However, crack growth due to creep can also occur under load varying conditions when load rising time is so long that accumulated creep deformation near the crack tip is not negligible.In this paper, the estimation equation of the Ctparameter which can be applied to the case of slow load rising, i.e., (Ct)r, is explained. And the correlation between (Ct)r at the end of the load increasing period and Ct at the beginning of the succeeding load hold period is discussed. Finite element analyses of several cases with various loading conditions were performed and results were presented to show the effectiveness of the proposed Ct estimation scheme. The general applicability of the equation is also discussed.
关键词:
creep
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null
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null
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null
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null
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null
Journal of Magnetism and Magnetic Materials
The local structure and the electron paramagnetic resonance (EPR) g factors g(parallel to), g(perpendicular to) and the hyperfine structure constants A(parallel to) and A (perpendicular to) for the trigonal Co2+ center in K4CdCl6 are theoretically investigated by using the perturbation formulas of the EPR parameters for a 3d 7 ion in trigonal symmetry based on the cluster approach. In these formulas, the contributions to the EPR parameters arising from the admixture of different energy levels, covalency effect and low symmetry distortion are included. The parameters related to the above effects are obtained from the optical spectral data and the local geometrical relationship of the studied system. By analyzing the EPR spectra, we find that the impurity-ligand bonding angle beta (approximate to53.54degrees) related to the C-3-axis in the Co2+ impurity center is smaller than the corresponding metal-ligand bonding angle beta(H) (approximate to 54.90degrees) in the host K4CdCl6. From the difference Deltabeta between the bonding angle beta (or beta(H)) and the corresponding angle beta(0) (approximate to54.74degrees) in cubic symmetry, the chlorine octahedron changes from compression (Deltabeta(H) = beta(H) - beta(0) > 0) in the host to elongation (Deltabeta = beta - beta(0) < 0) in the impurity center. The calculated EPR parameters, especially the anisotropies of the g and A factors for K4CdCl6: Co2+ based on the angle beta show good agreement with the observed data. The theoretical studies on the local structure for Co2+ in K4CdCl6 would be helpful to understand the structure properties for the equivalent octahedral transition-metal M site in the isostructural A(3)M'MO6 compounds. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
defect structure;electron paramagnetic resonance;crystal- and;ligand-field;Co2+;K4CdCl6;atomic screening constants;magnetic-properties;superposition model;rh(iii) compounds;scf functions;sr3mrho6 m;cr3+ ions;crystals;impurities;transition
Acta Chimica Sinica
The molal enthalpies of solution of VOSO(4)center dot 2.76H(2)O(s) with various molalities in water and in aqueous sulfuric acid (0.5 mol.kg(-1)) Delta(s)H(m), were measured by a solution-reaction isoperibol calorimeter at 298.15 K. The value of -Delta(s)H(m) in aqueous sulfuric acid was lower than that in water, which shows that energy state of VOSO(4) in aqueous H(2)SO(4) was higher than that in pure water. An improved Archer's method was put forward in terms of ionic association equilibrium of VOSO(4) and second dissociation equilibrium of H(2)SO(4). Using the improved method, the standard molal enthalpies of solution Delta(s)H(m)(circle minus) = 29.18 kJ.mol(-1) in pure water and Delta(s)H(m)(circle minus) = -25.79 kJ.mol(-1) in aqueous sulfuric acid were obtained, respectively. According to calculation, the molality of VO(2+) was larger in VOSO(4)-H(2)SO(4) mixed solution than that in water.
关键词:
vanadium redox flow battery;enthalpy of solution;vanadyl sulfate;sulfuric acid;vanadyl sulfate;sulfuric-acid;redox;v(iv)/v(v);battery;cell
