Interface reaction between oxide glasses and Fe-Al-Si magnetic alloy

The interface reactions between oxide glasses and magnetic alloy, Fe-Al-Si (so-called Sendust), were analysed. The oxide glasses used were SiO₂-PbO, SiO₂-Na₂O, SiO₂-Li₂O and B₂O₃-Na₂O binary glasses. It was observed that the lattice constant of the alloy decreases and the saturation magnetic-flux density of the alloy increases on reaction with the glasses. It was found that the aluminium atoms in the alloy diffuse to the interface and dissolve into the glass melt as Al³⁺ ions, leading to the iron-rich composition of the alloy. On the other hand, Pb²⁺, Na⁺ and H⁺ ions in the molten glasses were reduced at the interface. Metallic lead particles about 20 m in diameter were found to be dispersed in the SiO₂-PbO melt. Reduced sodium was thought to evaporate from the SiO₂-Na₂O melt, and H₂ gas bubbles were observed at the interface between B₂O₃-Na₂O melt and the alloy. These reactions were analysed based on the standard free energy diagrams of oxidation-reduction reaction, and expressed as 3Pb _glass ²⁺ +2Al_alloy 3Pb+2Al _glass ³⁺ 3Na _glass ⁺ +Al_alloy 3Na+Al _glass ³⁺ 6H _glass ⁺ +2Al_alloy 3H₂+2Al _glass ³⁺     

Characterization and properties of polypropylene‐block‐poly(ethylene‐co‐propylene) synthesized by short‐period polymerization

The morphology and mechanical properties of novel block copolymers consisting of isotactic polypropylene (PP) and ethylene–propylene rubber (EPR) synthesized by a short‐period polymerization method were examined using differential scanning calorimetry, atomic force microscopy, dynamic mechanical analysis, and a rheooptical technique. It was found that the novel block copolymers show a single glass transition and EPR segments are trapped into the amorphous region of PP. Furthermore, the rheooptical analysis demonstrates that a drawing process of the EPR‐rich block copolymer induces orientation of the PP lamellae in the EPR matrix. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 958–964, 1999     

Rheological properties for binary blends of i-PP and ethylene-1-hexene copolymer

The dynamic viscoelastic properties for binary blends consisting of an isotactic polypropylene (i-PP) and an ethylene-1-hexene copolymer (EHR) were investigated in both solid and molten states to reveal the relation between miscibility in the molten state and the morphology in the solid state. In this study, two types of EHRs were employed: “ethylene-rich” EHR and “1-hexene-rich” EHR. The blend of i-PP and EHR of 30 mol % 1-hexene content shows a very long time relaxation due to the phase separation in the molten state. The blend film shows two separate glass-relaxation processes associated with those of the pure components. These indicate that the blend shows phase-separated morphology in the solid state as well as in the molten state. On the other hand, dynamic moduli in the molten state of the blends of i-PP and EHR of 57 mol % 1-hexene were found to be intermediate between those of individual pure components. Furthermore, the apparent activation energy of the blends is constant and is identical with those of i-PP and the EHR. The blend films show a single glass-relaxation process at the temperatures between those of the pure components, indicating that the EHR molecules are incorporated in the amorphous region of i-PP in the solid state. Accordingly, it was found that the polymer miscibility in the molten state for the i-PP/EHR blends directly affects the morphology in the solid state. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 467–474, 1997     

Fuel ethanol production from sweet sorghum using repeated-batch fermentation

Ethanol was efficiently produced from three varieties of sweet sorghum using repeated-batch fermentation without pasteurization or acidification. Saccharomyces cerevisiae cells could be recycled in 16 cycles of the fermentation process with good ethanol yields. This technique would make it possible to use a broader range of sweet sorghum varieties for ethanol production.     

Absorption coefficient spectra of μc-Si in the low-energy region 0.4–1.2 eV

Optical absorption spectra in the low-energy region 0.4–1.2 eV is reported for μc-Si:H using a photothermal deflection spectroscopy technique. Absorption coefficient spectra in the low-energy region contain important information related to defects and hydrogen. It is demonstrated that there is a good correlation between electron spin densities and integrated absorption coefficient spectra from 0.7 to 1.2 eV. The amount of the hydrogen molecules in microvoids is much larger in μc-Si:H than that in a-Si:H. Light illumination effects in PDS spectra has also been studied from a view point of photo degradation of the μc-Si:H.     

The creation of hydrogen radicals by the hot-wire technique and its application for μc-Si:H

A new method, Hot-wire assisted PECVD, is proposed for preparing μc-Si:H films. This method is constructed of two parts, plasma-enhanced CVD (PECVD) and hot-wire for exciting hydrogen. Both the crystalline grain size and the volume fraction of Si crystallites in the film are improved by this preparation method compared with those of the conventional PECVD. The results obtained are interpreted by the enhanced hydrogen-radical density. The importance of control of H radicals is discussed for the growth of the crystallite.     

Life of Magnetic Electroless Co-P Thin Films

Effective life of electroless Co-P (2.5 wt%) thin films of about 100 nm in thickness was evaluated for both magnetic characteristics and corrosion. The Co-P films were grown on rigid Al substrates overcoated with nonmagnetic Ni-P thick films and were finally covered with electroplated Rh thin films of 120 nm - 180 nm in thickness. The life of the magnetic characteristics was defined as the time to reach 10% deviation from the initial values of Hc (coercive force), Br (remanence), and S (squareness of hysteresis loop). The life of the films for corrosion was defined as the induction period of corrosion. An increase of Hc was observed above 80°C for isothermal annealing, but Br and S were unchanged. The activation energy of the variation of Hc was approximately 0.7 eV below 144°C. The life of magnetic characteristics was estimated to be approximately 4.1 × 104 ? 2.3 × 105 hrs at 55°C corresponding to the allowable maximum temperature in field service. The life for corrosion was influenced by the quality of Rh films.