Automatisierte Ermittlung von Fließkurven und deren Darstellung durch eine empirische Beziehung mit Anpassung in vorgegebenen Bereichen der Formänderung

Beschreibung einer einfachen Versuchsanordnung zur Durchführung von kontinuierlichen Zylinderstauchversuchen mit automatischer Erfassung der Meßwerte. Vorschlag für nachgeschaltete elektronische Zusatzeinrichtungen zur automatischen Wiedergabe der Fließkurve durch eine beliebige empirische Beziehung mit rechnergestützter Anpassung in vorgegebenen Bereichen der Formänderung und Angabe des Korrelationskoeffizienten. Versuchsergebnisse für die Stähle RSt 37-1 und QSt 52-3 Cu 3 im warmgewalzten und im kaltverformten Zustand.     

Beurteilung von Teigeigenschaften durch Zugversuche im Mikromaßstab

European Food Research and Technology - Es wird eine Mikromethode für Zugversuche aus Teigen beschrieben, die mit nur 10 g Mehl 6–8 Kraft-Dehnungs-Kurven liefert. Die Mikromethode wird...     

n-Butane Isomerization Catalyzed by Sulfated Zirconia Nanocrystals Supported on Silica or γ-Alumina

Supported sulfated zirconia catalysts with zirconia contents of 10, 20 and 50 wt% were prepared by impregnation of SiO₂ and γ-Al₂O₃ supports with H₂SO₄/ Zr(SO₄)₂ solutions followed by calcination at 923 K. The catalysts were characterized by X-ray diffraction, extended X-ray absorption fine structure measurements, thermal analysis, UV–vis spectroscopy, and electron microscopy. Tetragonal zirconia was detected in all silica-supported samples but only in the 50 wt% zirconia-containing alumina-supported sample, indicating high dispersion of zirconia on alumina. Alumina-supported samples retained additional sulfate, at least in part as Al₂(SO₄)₃. All samples were active in n-butane isomerization (1 kPa n-butane, 378 K). There was no relation between the presence of tetragonal zirconia in these samples and the catalytic performance.     

Porous Silicon Nitride Ceramics Prepared by Reduction–Nitridation of Silica

A new method for preparing porous silicon nitride ceramics with high porosity had been developed by carbothermal reduction of die-pressed green bodies composed of silicon dioxide, carbon, sintering additives, and seeds. The resultant porous silicon nitride ceramics showed fine microstructure and uniform pore structure. The influence of SiO₂ particle size and sintering process (sintering temperature and retaining time) on the microstructure of sintering bodies was analyzed. X-ray diffractometry demonstrated the formation of single-phase β-Si₃N₄ via the reaction between silicon dioxide and carbon at high temperature. SEM analysis showed that pores were formed by the banding up of rod-like β-Si₃N₄ grains. Porous Si₃N₄ ceramics with a porosity of 70–75%, and a strength of 5–8 MPa, were obtained.