Publikationen

Reiß, Stephanie; Grieseler, Rolf; Krischok, Stefan; Rädlein, Edda
The influence of Sahara sand on the degradation behavior of float glass surfaces. - In: Journal of non-crystalline solids, ISSN 0022-3093, Bd. 479 (2018), S. 16-28

https://doi.org/10.1016/j.jnoncrysol.2017.09.055

Prikhna, Tetiana; Romaka, Vitaliy; Eisterer, Michael; Shapovalov, Andrii; Kozyrev, Artem; Grechnev, Gennadiy; Boutko, Viktor; Goldacker, Wilfried; Habisreuther, Tobias; Vakaliuk, Oleksii; Halbedel, Bernd
Structure and superconducting characteristics of magnesium diboride, substitution of boron atoms by oxygen and carbon. - In: Advances in cryogenic engineering - materials: proceedings of the International Cryogenic Materials Conference (ICMC) 2017, (2017), S. 012023, insges. 8 S.

An x-ray analysis of MgB2-based materials shows that they contain MgB2 and MgO phases. According to a quantitative Auger analysis (taken after removing the oxidized surface layer by Ar ion etching in the microscope chamber) the MgB2 phase contains some amount of oxygen that approximately corresponds to the composition MgB2.2-1.7O0.4-0.6. Rietveld refinement of the MgB2 phase, based on EDX data with varying B/O content, leads to the composition MgB1.68-1.8O0.2-0.32. Ab-initio modelling of boron substitution by oxygen in MgB2 ([Delta]Hf =-150.6 meV/atom) shows that this is energetically favourable up to the composition MgB1.75O0.25 ([Delta]Hf =-191.4 meV/atom). In contrast to carbon substitution, where very small levels of doping can dramatically affect the superconducting characteristics of the material with concomitant changes in the electron density, oxygen substitution results in very little change in the superconducting properties of MgB2. The formation of vacancies at the Mg site of both MgB2 and substituted MgB1.75O0.25 was modelled as well, but has shown that such processes are energetically disadvantageous ([Delta]Hf of Mg0.875B2 and Mg0.75B1.75O0.25 are equal to -45.5 and -93.5 meV/atom, respectively).

https://doi.org/10.1088/1757-899X/279/1/012023

Halbedel, Bernd; Kazak, Oleg
Potenziale eines neuen Mahlverfahrens - die elektromechanische Zerkleinerung (EMZ). - In: Produktgestaltung in der Partikeltechnologie, ISBN 978-3-8396-1194-4, (2017), S. 181-196

Halbedel, Bernd;
Elektromagnetische Eigenschaften und Anwendungspotentiale von submikroskaligen, substituierten Hexaferritpulvern. - In: Workshop Elektroprozesstechnik, (2017), 8, insges. 17 S.

Im vorliegenden Beitrag werden Mikrowellen absorbierende AII/BIV substituierte Bariumhexaferrite (BHF) in einer glasigen Matrix durch Schnellkühlung der Schmelze mit der Zusammensetzung 40 Mol-% BaO + 27-(y+x) Mol-% Fe2O3 + x Mol-% AIIO + y Mol-% BIVO2 + 33 Mol-% B2O3 und anschließender bottom-up-Steuerung der Keimbildung und des Kristallwachstums (Glaskristallisationstechnik) synthetisiert. Dabei werden Substituent (paramagnetische Kationen: MnII, FeII, CoII, diamagnetisches Kation: TiIV) und Temperbedingungen (Temperatur, Haltezeit) systematisch variiert und wesentliche Struktur-Eigenschafts-Beziehungen zur Synthese der substituierten Bariumhexaferrite aufgeklärt. Die synthetisierten BHF-Pulver sind für die Herstellung von Bond/ Disbond-on-Command Klebstoffen und von maßgeschneiderten Absorbermaterialien sowie für sensorische magnetische Anwendungen geeignet. Die Herstellung der BHF-Pulver wurde im Labormaßstab erfolgreich getestet. Lösungsansätze für die industrielle Produktion werden vorgestellt.

Halbedel, Bernd; Kazan, Oleg
Development of electromechanical principle for wet and dry milling. - In: Proceedings of the VIII International Scientific Colloquium Modelling for Materials Processing, (2017), S. 223-229

The paper presents a novel electromechanical principle for wet and dry milling of different materials in which the milling beads are moved under time- and local-variable magnetic field. It is shown possibility to optimize the milling process in such milling machine by simulation of the gradient of vector electromagnetic field distribution in the working chamber. The mathematical model and simulation methods based on standard software packages are worked out. The results of numerical simulations and experimental measurements of electromagnetic field in working chamber of the developed and manufactured laboratory plant are in good correlation. With the obtained operating parameter dry milling experiments with crushed cement clinker and wet milling experiments of organic agents in the laboratory plant are executed and the results are discussed.