Experimental verification of some up-to-date concepts of mild carbon steel corrosion under boiler feedwater conditions

The results of systematic rig investigations of corrosion of carbon steel and iron in boiler feedwater have been presented. The chemical mechanism of corrosion at least at the initial period of contact between the metal and the deionised water flow at 150°C has been shown to be predominant. The dissolved oxygen has been proved to participate in the corrosion processes, reducing the rate of chemical corrosion at high concentrations. The anodic polarization and open-circuit potential decay curves for iron electrodes in sodium molybdate solutions have been used to reveal the anodic current maxima at Flade potentials derived from the Franck equation.

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Experimentelle Prüfung von modernen Konzepten, die Korrosionserscheinungen für Kohlenstoffstahl im Kesselspeisewasser umfassen

Zusammenfassung Es wurden die Ergebnisse der regelmäßigen Standsuntersuchungen von Korrosionserscheinungen für Kohlenstoffstahl und Eisen im Kesselspeisewasser betrachtet. Die chemische Korrosion überwog der elektrochemischen Korrosion, wenigstens im Anfang des Kontaktes zwischen Metall und entgastem, salzfreiem Wasser bei der Temperatur von 150°C. Der im Wasser gelöste Sauerstoff nimmt unmittelbar an den Korrosionsvorgängen teil. Die Erhöhung seiner Konzentration senkt die Geschwindigkeit der chemischen Korrosion. Durch anodische Potentialstromkurven und Abfall des Potentials bei der Polarisationsstromunterbrechung wurden die Untersuchungen der Eisenelektrode in Natriumolybdat-Lösungen durchgeführt. Es wurde das Maximum des Anodenstroms für Fladepotentiale ermittelt, die mit der Franck-Gleichung berechnet werden.

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Dedicated to Prof. Dr.-Ing. F. Mayinger's 60th birthday     

Temperature dependence of the spectrum of recombination radiation for indium phosphide n-p junctions

The spectrum of the recombination radiation from diffused indium phosphide n-p junctions was investigated at 77, 138, 210, and 298° K. The quantum energy in the maximum of the spectrum of recombination radiation differs from the corresponding energy gap values by 0.01 eV; this phenomenon is related to recombination processes at impurity levels.     

Refusing to twist: demonstration of a line hexatic phase in DNA liquid crystals

We report conclusive high resolution small angle x-ray scattering evidence that long DNA fragments form an untwisted line hexatic phase between the cholesteric and the crystalline phases. The line hexatic phase is a liquid-crystalline phase with long-range hexagonal bond-orientational order, long-range nematic order, but liquidlike, i.e., short-range, positional order. So far, it has not been seen in any other three dimensional system. By line-shape analysis of x-ray scattering data we found that positional order decreases when the line hexatic phase is compressed. We suggest that such anomalous behavior is a result of the chiral nature of DNA molecules.     

The Thermal Conductivity of Monocrystalline Gallium Garnets Doped with Rare-Earth Elements and Chromium in the Range 6–300 K

The effect of the additions of rare-earth elements Nd, Sm, Eu and Tb on the thermal conductivity of gadolinium-gallium garnets and besides the influence of the joint doping with Nd and Cr on the thermal conductivity of gadolinium-gallium and more compound gadolinium-scandium-gallium, gadolinium-magnesium-zirconium-gallium and yttrium-scandium-gallium garnets have been investigated.     

Temperature variation of the phonon frequencies in V3Si along the [110] direction by the X-ray inelastic scattering

The investigation of the intensity of X-ray diffuse scattering by the lattice vibrations along the second-order symmetry axis in V₃Si single crystals is performed at different temperatures from 300 to 8 K and the phonon dispersion curves in this direction are determined. It is found that the phonon frequencies of all modes decrease with lowering temperature.