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991.
The gallides SrRh2Ga2, SrIr2Ga2, and Sr3Rh4Ga4 were obtained from the elements by induction melting and subsequent annealing. They were investigated by powder and single‐crystal X‐ray diffraction: CaRh2B2 type, Fddd, a = 573.2(1), b = 1051.3(1), c = 1343.7(2) pm, wR2 = 0.0218, 398 F2 values, 15 variables for SrRh2Ga2; a = 576.0(1), b = 1045.5(1), c = 1350.6(3) pm for SrIr2Ga2, and Na3Pt4Ge4 type, I$\bar{4}$ 3m, a = 777.4(2) pm, wR2 = 0.0234, 190 F2 values, 11 variables for Sr3Ir4Ga4. The gallides SrRh2Ga2 and Sr3Ir4Ga4 exhibit complex, covalently bonded three‐dimensional [Rh2Ga2] and [Ir4Ga4] networks with short Rh–Ga (241–246 pm) and Ir–Ga (243–259 pm) distances. The strontium atoms fill large cages within these networks. They are coordinated by 8 Rh + 10 Ga in SrRh2Ga2 and by 4 Ir + 8 Ga in Sr3Ir4Ga4. The structure of SrRh2Ga2 is discussed along with the monoclinic distortion variants HoNi2B2 and BaPt2Ga2 on the basis of a group‐subgroup scheme. 相似文献
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F. J. Garcia‐Garcia T. Y. Chiu P. Skeldon G. E. Thompson 《Surface and interface analysis : SIA》2015,47(1):30-36
Cathodic polarization of aluminium and Al–0.18 wt.% Mg and Al–0.08 wt.% Ti alloys in 0.24 mol dm?3 nitric acid solution at 38 °C has been employed to assist understanding of the roles of alloying elements in electrograining. The findings indicate that additions of magnesium and titanium to aluminium accelerate the corrosion of the substrate under the alkalization caused by the cathodic reactions. The accelerated dissolution and the consequent formation of hydrated alumina result in a decreased net cathodic current density in potentiostatic and potentiodynamic polarization conditions relative to the behaviour of aluminium. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Electrodeposition and characterization of Zn–Sn alloy coatings from a deep eutectic solvent based on choline chloride for corrosion protection 下载免费PDF全文
S. Fashu C. D. Gu J. L. Zhang W. Q. Bai X. L. Wang J. P. Tu 《Surface and interface analysis : SIA》2015,47(3):403-412
With the aim of obtaining high corrosion resistant Zn–Sn alloy coatings from an ionic liquid, the effects of electrodeposition potential and electrolyte composition on the electrodeposition behavior, film composition, morphology and corrosion performance were investigated. Cyclic voltammograms indicate that Zn and Sn were co‐deposited at distinct reduction potentials as pure Zn and Sn elements. In addition, the phase composition analysis also showed that the obtained Zn–Sn alloy deposits (8 wt.%–45 wt.% Zn) consist of a two‐phase mechanical mixture of small aggregates of Zn and Sn metals. The Zn content of the alloy significantly increases as the electrodeposition potential and electrolyte Zn (II)/Sn (II) ratio increase. The corrosion performance study of the obtained Zn–Sn coatings showed that they have a passivation behavior and their corrosion resistance increases as the alloy‐Sn content increases. To improve their morphological properties, ethylene diamine tetraacetic acid additive was introduced into the electrolyte and greatly improved the morphology and corrosion resistance of the deposits. For the first time, it was shown that high corrosion resistance Zn–Sn coatings can be obtained from ionic liquids. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献