Barium potassium bismuth oxide: A review

Ba_1–x K _x BiO₃(BKBO) has aT _c (onset) of 34 K. It is the highest-temperature oxide superconductor which is cubic, with a coherence length of 30–60 Å. The basic properties of this compound are reviewed.     

A new model with non-spherical interactions for dense polymer systems

Summary We introduce a new general model for the simulation of dense macromolecular systems. It consists of basic ellipsoidally shaped units stringed together to form chains, including branched and side chains. The ellipsoidally shaped unit can vary in its principal axes, allowing for flexible modeling of a chain. The variation in the main principal axis is used for the intramolecular potential of the bond type. Intramolecular units interact through a harmonic bond-angle potential and the intermolecular interaction is modelled by a confocally decreasing Lennard-Jones potential. We present the model for the special case of a polycarbonate and indicate the generalization to other cases.     

Desoxidationsgleichgewichte von Titan,Aluminium und Zirconium in Eisenschmelzen bei 1600 °C

Verwendung einer Doppelelektrolytzelle aus ZrO₂(CaO) mit ThO₂(Y₂O₃)-Beschichtung zur Untersuchung der Desoxidationsgleichgewichte Fe–O–Ti, Fe–O–Al und Fe–O–Zr bei 1600 °C über EMK-Messung sowie Probenahme und chemische Analyse. Ermittlung der Sauerstoffaktivitäten in Abhängigkeit vom Gehalt an Titan, Aluminium oder Zirconium in der Eisenschmelze sowie der Gleichgewichtskonstanten und Wirkungsparameter e^x_x. Vergleich der analytisch bestimmten und thermodynamisch berechneten Sauerstoffgehalte.     

Die Schadenslinie im Wöhlerdiagramm

The Damage Line of the Wöhlerdiagram Sometimes, Wöhlerdiagrams are supplemented by so-called damage lines or French-lines, synonymously. Due to the statistical nature of fatigue events, however, Wöhlerdiagrams more and more are statistically ascertained and described by curves which commonly are referred as to probability-stress-cycle curves (P-S-N). Accordingly, it was to find out, whether the feature “damage” might be described in a similar way, aiming at P_d-S-N curves (P_d = Probability of damage) within the expected damage field. Using the steels Ck 35 and 34 CrMo 4 quenched and tempered, the statistically planned and evaluated investigations showed that within the Wöhlerdiagrams of these steels large damage fields can be defined which extend from far before the ranges of finite life till far into these ranges (of scatter). P_d-S-N curves are given. Satisfactory shortcut-methods for estimating such curves using features as specimens' temperature and deformation during cyclic pre-loading could not be developed. By progressively increasing and – another sample – decreasing load tests to the same account of 0,34 Palmgren-Miner-damage specimens showed remarkable differences when compared within French's concept of damage.     

Gültigkeits- und Anwendungsbereich der Rißbruchmechanik

Fracture Mechanics Range of Validity and Application. The range of validity and application of the linear-elastic and elasto-plastic fracture mechanics is determined according to practicable quantitative criteria. The former is applicable to the low stress brittle fracture in brittle materials, the latter is applicable to the higher stress brittle and tear fracture in tougher materials. The real continuum mechanics fracture criterium is not yet determined. The linear-elastic fracture mechanics is widely applicable to fatigue fractures. Taking into account the interaction and sequence effect of low and high load amplitudes is necessary. The fracture mechanics approach to brittle and fatigue fracture is compared with traditional testing techniques.