Search results for "Metallurgy"
showing 10 items of 1419 documents
Valorisation of industrial iron oxide waste to produce magnetic barium hexaferrite
2016
Barium M-type hexagonal ferrite (BaM, BaFe12O19) is an immensely important magnetic material, which we have successfully made from the simple valorisation of Fe-rich industrial waste from steel wire drawing, with addition of BaCO3 and heating in air to 1000 degrees C. The optimum ratio of Fe. Ba (producing 86 wt% BaM) was found to be 11: 1 (non-stoichiometric), and secondary phases of alpha-Fe2O3 (non-magnetic) and ZnFe2O4 (poorly antiferromagnetic) were always present. This material consisted of small submicron platelets. A hard magnetic ferrite was produced with Ms=48.6 A m(2) kg(-1) and H-c=211.5 kA m(-1). The highest density was achieved by sintering samples with Fe: Ba ratios of 11: 1 …
Investigation on Ash Slagging Characteristics During Combustion of Biomass Pellets and Effect of Additives
2017
This study reports a systematic investigation into ash slagging behavior during combustion of barley straw and barley husk pellets with or without additives in a residential pellet burner. The slagging tendencies of the pellets were evaluated based on the amount, chemistry, mineralogy, and morphology of inlet ash formed as slag and sintering degrees of residual ash. The barley straw and husk pellets showed high slagging tendencies with 39 and 54 wt % ingoing ash formed as slag. Analyses using X-ray fluorescence and scanning electron microcopy combined with energy-dispersive X-ray spectroscopy revealed high concentrations of K, Si, and Ca but a minor amount of P in barley straw slag. The sla…
Heteroeptiaxial growth of alloy monolayers on W(110)
2005
Abstract We studied the initial growth of Co 1 - x Fe x films on W(1 1 0) using scanning tunneling microscopy and spectroscopy (STM and STS), in combination with low-energy electron diffraction (LEED). For Co-rich alloys the deposition at room temperature followed by high-temperature annealing is not equivalent to the deposition at high substrate temperatures, in contrast to the case of Fe-rich alloys. While room temperature deposition results in a structure consisting of small islands even after annealing, deposition at high substrate temperatures leads to large coalesced areas. Sequential deposition of pure Co and pure Fe results in phase separated areas of Co- and Fe-rich areas. Only, in…
MoO (x≤2) ultrathin film growth from reactions between metallic molybdenum and TiO2 surfaces
2001
Abstract Exposures to oxygen at room temperature and annealings under vacuum were carried out on deposits obtained from molybdenum interacting with (1 1 0) TiO 2 surfaces in order to obtain molybdenum oxide ultra thin films. Exposures to oxygen at room temperature show that the interfacial molybdenum oxide layers resulting from the TiO 2 /Mo interactions are inactive towards oxygen whereas the metallic molybdenum clusters, which grew on top of the interfacial layers, oxidise into MoO 3 . Besides, during annealings under vacuum, substrate oxygen anions can diffuse into the deposit. Thus, between 400 and 500°C, molybdenum oxide layers are progressively oxidised into MoO 2 . Moreover, from the…
Anomalous Kinetics of Diffusion-Controlled Defect Annealing in Irradiated Ionic Solids
2017
The authors thanks A. Ch. Lushchik, M. Izerrouken, and V. Lisitsyn for stimulating discussions. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euroatom research and training programme 2014-2018 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. R.V. acknowledges the financial support by the MEIC (Ministerio de Economa, Industria y Competitivad; Project ENE2015-70300-C3-1-R). The calculations were performed using facilities of the Stuttgart Supercomputer Center (Project DEFTD 12939).
Growth of ZnO crystals by vapour transport: Some ways to act on physical properties
2006
Nowadays, the growth of ZnO by vapor transport in silica ampoules is generally made in presence of graphite. As it has been already shown, this means that the growth process is carried out in presence of a Zn excess. In order to control that and act, as a consequence, on the physical properties of crystals we have performed a systematic study of the growth process in a wide range of Zn excess compositions using well defined experimental conditions. As a preliminary characterization, optical absorption and electrical properties have been analyzed at room temperature. The results show how some physical properties of as-grown ZnO crystals can be changed in a controlled way by an adequate combi…
The anodic and cathodic dissolution of Al and Al–Cu–Mg alloy
2010
Abstract Atomic emission spectroelectrochemistry (AESEC) was used to monitor the release of Al from 99.99% aluminum (1199 alloy) and Al, Mg, and Cu from 2024 Al alloy in 30 g/l NaCl electrolyte as a function of pH. The cathodic dissolution of Al was demonstrated and attributed to an increase in the pH at the interface due to the water reduction reaction. The dissolution of Mg was also observed but was a more complex function of current probably depending on the interfacial pH and the Al dissolution rate. The detachment of copper-rich particles was observed as very rapid spectroscopic emission transients (peak width
Anwendung der Mößbauer-Spektroskopie auf die Untersuchung von Deckschichten in Naturumlaufkesseln
1978
57Fe-Mosbauer-spektroskopische Transmissions- und Reflexionsmessungen wurden zur Aufklarung der qualitativen und quantitativen Zusammensetzung von Deckschichten auf der Innenseite von Rohren aus Naturumlaufkesseln vorgenommen. Die Deckschichten waren bei 120 bis 174 atu, 320 bis 353 °C, einem pH-Wert zwischen 9,5 und 10,5 und einem Gehalt an P2O5 und SiO2 von < 10 bzw. < 4 mg/l auf den Rohrinnenflachen (Werkstoff 15 Mo 3: 0,12%C, 0,15% Si, 0,5% Mn, 0,04% P, 0,04% S, ⩽ 0,3% Cr, 0,25% Mo, Rest Fe; St. 45. 8. III: < 0,22% C, 0,1% Si, ⩾ 0,45% Mn, 0,05% P, 0,05% S, ⩽ 0,3% Cr, Rest Fe) innerhalb von maximal 127000 h entstanden. Die Mosbauer-spektroskopischen Untersuchungen, unterstutzt durch eine…
Heterogeneous vs Homogeneous Palladium Catalysts for Cross-Coupling Reactions
2012
A large number of immobilized-Pd-catalysts for cross-coupling reactions have been introduced in the last decade. Are the observed catalyzed reactions truly heterogeneous or are they homogeneous due to leached palladium? This account critically addresses the leaching issue by selectively referring to some of the newly developed catalytic systems in an attempt to evaluate said systems based on uniform criteria. The report is concluded by identifying the relevant chemical and structural challenges in the field.