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[en] A density-functional--based theory is developed for calculation of the total energy and pressure of random substitutional alloys within the Korringa-Kohn-Rostoker coherent-potential approximation. The theory is used to calculate the concentration variation of the equilibrium lattice spacing of α-phase Cu/sub c/Zn/sub 1-c/ alloys. We find, in agreement with experiment, that the variation is almost linear and that it deviates from Vegard's rule
[en] Atmospheric corrosion behaviors of Zn, Zn-5%Al and Zn-55%Al coated steels have been investigated under cyclic wet-dry environments containing chloride ions. The wet-dry cycle was carried out by alternate exposure to immersion in 0.5 M (or 0.05 M) NaCl solutions and drying at 25 .deg. C and 60 %RH. The polarization resistance Rp and solution resistance Rs were monitored by AC impedance technique. From the obtained 1/Rp and 1/Rs and values, the corrosion rate of the coatings and the Time of Wetness (TOW) were estimated, respectively. Effects of chloride ions and TOW on the corrosion rates of Zn, Zn-5%Al and Zn-55%Al coatings and appearance of red rust (onset of underlying steel corrosion) under wet-dry cycles are discussed on the basis of the corrosion monitoring data
[en] The purpose of the present investigations is to study the effect of moulding sand on decreasing shell wall thickness of mould cavities for economical and statistically controlled hybrid rapid casting solutions (combination of three dimensional printing and conventional sand casting) for zinc alloys. Starting from the identification of component/ benchmark, technological prototypes were produced at different shell wall thicknesses supported by three different types of sands (namely: dry, green and molasses). Prototypes prepared by the proposed process are for assembly check purpose and not for functional validation of the parts. The study suggested that a shell wall with a less than recommended thickness (12mm) is more suitable for dimensional accuracy. The best dimensional accuracy was obtained at 3mm shell wall thickness with green sand. The process was found to be under statistical control
[en] Metal-semiconductor contact is very important for the operating property of semiconductor detector. Cd0.96 Zn0.04 Te semiconductor crystal was grown with Bridgman method, and the crystal was cut and polished. EPMA (Electron Probe Micro Analyzer) and ICP-MS (Inductively Coupled Plasma Mass Spectrometry) analysis were done to obtain the chemical composition and impurity of the crystal. Metal contact was deposited with thermal evaporator on both sides of the crystal. Detectors with Au/CZT/Au and In/CZT/Au structure were made, and I-V curve and the energy spectrum were measured with the detectors. It could be seen that the detector with the In/CZT/Au structure has superior property than the detector with Au/CZT/Au structure when the crystal resistivity was low. However, the metal contact structure effect becomes low when the crystal resistivity was high
[en] We present the optical properties of zinc-blende CdSe and ZnSe ¯lms, which have been determined by using vacuum ultra-violet spectroscopic ellipsometry (SE) whose spectral range is from 0.7 to 9.0 eV at room temperature. We observed new critical point energies, whose observation by SE has not been reported so far, in the spectral range above 6 eV. We interpret these new peaks as a previously reported transition from a band-structure calculation. The values of the critical point energies were determined from numerically calculated second energy derivatives of these data.