Experimental Modelling using Low Melting Point Metallic Melts: Relevance for Metallurgical Engineering

This paper describes model experiments with liquid metals of low melting point as an important tool to investigate the flow structure and related transport processes in melt flows being relevant for metallurgical applications. Three examples have been selected to demonstrate the benefit of such experiments, namely the electromagnetic stirring of a metallic melt in a pool, the directional solidification of Al‐Si alloys under the influence of an electromagnetically driven flow and the behaviour of a liquid metal bubble plume if a vertically travelling field is applied. Results of flow measurements are presented and the relevance for metallurgical processes is discussed.     

Das Ausbeulen von Plattenstreifen,deren Dicke sich sprungweise ändert

Zusammenfassung Die nachfolgenden Untersuchungen haben zum Ziel, den Widerstand unendlich langer Plattenstreifen gegen Ausbeulen zu bestimmen, wenn sie durch Aufschwei?en schm?lerer Platten versteift werden. Im besonderen wird der zweistufige Plattenstreifen behandelt und bei gleicher Masse die Beulsicherheit eines abgestuften Streifens mit einem Streifen unver?nderlicher Dicke verglichen.     

Bücherschau

Ohne Zusammenfassung VDI     

Impact of the Electromagnetic Brake Position on the Flow Structure in a Slab Continuous Casting Mold: An Experimental Parameter Study

Metallurgical and Materials Transactions B - Flow measurements are performed in a slab model for continuous casting of steel under the influence of a ruler type Electromagnetic Brake (EMBr). The...     

Assessment of environmental tobacco smoke exposure: urinary cotinine concentrations in children are strongly associated with the house dust concentrations of nicotine at home

In the present study the possibility of using nicotine in house dust as an index of environmental tobacco smoke (ETS) exposure was evaluated in an environmental investigation of 23 children with asthma. A standardized procedure for house dust sampling of nicotine with a filter holder connected to a vacuum cleaner, for a defined time and area was developed (F-nicotine). Also, house dust sampling was carried out from the vacuum cleaner bags of the homes (VC-nicotine). There was a larger variation in VC-nicotine (13-655, median 66 microg/g) compared with F-nicotine (15-393 median 156 microg/g). There were statistically significant associations between an inquiry data based ETS exposure index on the one hand, and urinary cotinine concentrations in children (U-cotinine), F-nicotine and VC-nicotine of their homes, on the other. The strong correlation between U-cotinine and F-nicotine (rs = 0.93; P < 0.0001) indicates that the new standardized house dust sampling method should be useful in ETS exposure assessment. However, further validation by a larger sample size with repeated measurements in the same homes is needed.     

Environmental exposure to lead and arsenic among children living near a glassworks

Concentrations of lead (Pb) in blood (B-Pb, geometric mean 34.6 micrograms l-1, n = 127) and inorganic arsenic (As) and its metabolites in urine (U-As, mean 5.1 micrograms/g creatinine, n = 35) did not differ between children living in a village close to a glassworks emitting both Pb and As and children living in a reference area. There was no significant effect on B-Pb and U-As related to parents working at the glassworks or consumption of domestically grown vegetables. Neither was there any significant effect upon B-Pb of sex, age, potentially lead-exposing hobbies, or consumption of canned foods. Boys had higher U-As than girls (5.8 vs 4.2 micrograms/g creatinine, p = 0.005), and there was a decrease with age (range 8.4-10.4 years, 27% per year, p = 0.01). Further, parental smoking habits had a significant effect on both B-Pb and U-As. In children of non-smoking parents the B-Pb was 30 micrograms l-1, in children with one parent who smoked 39 micrograms l-1 (smoking father 37, smoking mother 41 micrograms l-1) and in children with two parents who smoked 47 micrograms l-1 (p less than 0.001). The corresponding values for U-As were 4.2, 5.5, and 13 micrograms/g creatinine, respectively (p = 0.01).     

Measurements of the bulk velocity during solidification of metallic alloys

The ultrasound Doppler velocimetry (UDV) was applied to measure the bulk flow in a Sn-15 wt pct Pb alloy solidified directionally from a water-cooled copper chill. The flow is driven by a rotating magnetic field (RMF). Our results show that the velocity profiles undergo distinct modifications during solidification indicating the occurrence of more sophisticated flow patterns as known from the isothermal case. Furthermore, the UDV data allow an assessment of the current position of the dendritic solidification front. This research is supported by the Deutsche Forschungsgemeinschaft (DFG) in the form of the SFB 609 “Electromagnetic Flow Control in Metallurgy, Crystal Growth and Electrochemistry.” This support is gratefully acknowledged by the authors.