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961.
The corrosion behaviour of nitrogen-containing austenitic stainless steel in methanol containing different concentrations
of H2SO4, HCl, LiCl and H2SO4 + HCl has been investigated using a potentiostatic polarization method. The cathodic reaction in the H2SO4, HCl and H2SO4 + HCl solutions was proton reduction whereas in the neutral LiCl solution, oxygen reduction was the predominant cathodic
reaction. Active, passive and transpassive behaviours were observed only for higher concentrations of H2SO4 (0.01–2.0 M) due to the inherent water content. A cathodic loop, characterized by measured negative current in the anodic
region, was also observed in solutions, in which the concentration of H2SO4 was 1.0 M or higher. The relative stability of the passive films decreased as the H2SO4 concentration increased, and thus the steel suffered from mild pitting corrosion. In the chloride environment, the rate of
corrosion increased as the Cl− ion concentration increased. The presence of acid along with Cl− ions enhanced corrosion, and the corrosion rate increased significantly. The steel suffered from mild intergranular corrosion
in acidic chloride solutions of methanol. In the H2SO4 + HCl solutions, passive films were only formed when the H2SO4 to HCl concentration ratio was greater than ∼10:1. 相似文献
962.
963.
The effect of a gas dissolved in a liquid on the variation of the refractive index of the compressed mixture was studied.
The compression process was monitored with the aid of a holographic interferometer. The sensitivity of this method allows
the compressibility of water and the solubility of helium and nitrogen to be studied at pressures below 4 atm. A procedure
for obtaining qualitative and quantitative data on the solubility of gases in liquids is proposed. 相似文献
964.
V. A. Kagadei E. V. Nefyodtsev D. I. Proskurovsky S. V. Romanenko 《Technical Physics Letters》2003,29(11):897-900
Using one-or two-layer films of transition metals, it is possible to determine the atomic hydrogen flux density under reduced
gas pressure conditions (10−1–10−3 Pa). The method consists in monitoring a change in the film resistance caused by selective dissolution of atomic hydrogen
in the metal during exposure of the film in a mixed atomic-molecular flow, followed by determining a characteristic time τ
required for the hydrogen concentration in the film to reach 63% of the maximum possible level. The hydrogen flux density
is then calculated within the framework of a simple mathematical model of the film saturation with hydrogen described by a
relaxation law. The proposed method is characterized by a high selective sensitivity to atomic hydrogen. The atomic hydrogen
flux density in a mixed atomic-molecular flow can be determined in a range from 5×1013 to 1016 cm−2 s−1. 相似文献
965.
X. X. Xi X. H. Zeng A. V. Pogrebnyakov A. Soukiassian S. Y. Xu Y. F. Hu E. Wertz Q. Li Y. Zhong C. O. Brubaker Z.-K. Liu E. M. Lysczek J. M. Redwing J. Lettieri D. G. Schlom W. Tian H. P. Sun X. Q. Pan 《Journal of Superconductivity and Novel Magnetism》2003,16(5):801-806
The recently discovered superconductor MgB2 with T c at 39 K has great potential in superconducting electronics. In this paper, we review the deposition techniques used for MgB2 thin films in the light of a thermodynamic study of the Mg-B system with the calculation of phase diagrams (CALPHAD) modeling technique. This thermodynamic study identifies a growth window in the pressure–temperature phase diagram, in which the magnesium pressure is very high for likely in situ growth temperatures. A Hybrid Physical–Chemical Vapor Deposition (HPCVD) technique that successfully achieves such a high Mg pressure is shown to produce in situ epitaxial MgB2 thin films with bulk superconducting properties. 相似文献
966.
Electromechanical properties of the 0-0-2-2 type composite based on platelike crystals of solid solutions of ferroelectric
relaxors of the Pb(A1/3Nb2/3)O3-PbTiO3 system (A = Zn, Mg) have been studied for the first time. Factors accounting for the record values of some effective parameters
of this composite are considered. The relationship between the components of the elastic compliance tensor of the layered
structures forming the composite and the positions of maxima of the effective hydrostatic parameters is established. 相似文献
967.
The results of experimental investigation of an Er-doped fiber bidirectional ring laser with a 90° Faraday rotator in the cavity are presented. Two theoretically predicted regimes of the bidirectional generation of modes propagating in opposite directions with either complex-conjugate or orthoconjugate polarization states have been realized in practice. In each of these regimes, stable bidirectional generation of only one longitudinal mode propagating in each direction is possible. The former regime ensures significant stabilization of a nonreciprocal frequency shift between the modes propagating in opposite directions, this shift being determined by the Faraday phase rotator. 相似文献
968.
969.
V. A. Pozdnyakov 《Technical Physics Letters》2003,29(2):151-153
The problem of brittle crack development in a nanocrystalline material has been theoretically studied. Expressions describing
the conditions of crack stability are obtained. 相似文献
970.
I. I. Vintizenko V. I. Gusel’nikov A. I. Zarevich S. S. Novikov 《Technical Physics Letters》2003,29(4):294-296
Autooscillation regimes in a relativistic magnetron with external mutual coupling of cavities have been studied. It is demonstrated that the interaction of oscillations under mode competition conditions significantly increases the stability of the working oscillation mode and improves the spectral characteristics of radiation. 相似文献