General Information: The growing use of zinc-coated steel sheet in a variety of sectors (motor industry, consumer durables and construction industry) has led to an increase in the zinc content of home scrap, a large proportion of which is recycled in L-D steelworks. From a metallurgical point of view, the Zn coating of the scrap does not interfere with the steel production process, nor does it normally affect product quality. However, the zinc does accumulate in the process dusts. Despite their high iron content, typically around 60 per cent, these dusts cannot be recycled in the sintering plant or the blast furnace because of the zinc load without additional, usually complicated processing stages, above all owing to the risk of scaling in the blast furnace. On the other hand, the typical zinc content of these dusts of 2 per cent is too low to be recycled in zinc foundries. From the purely economic point of view, this currently requires Zn concentrations of well above 30 per cent. If the dusts and slurries from the waste gas cleaning system of an L-D converter are to be recycled internally, the zinc load must be reduced to a level that will not damage the blast furnace. The main source of the zinc in the dusts from waste gas purification is the scrap used in the converter, the Zn content of which can vary considerably. Some types of scrap are practically zinc-free, e.g. the uncoated process scrap or comparable new scrap. However, a large proportion of the scrap used, with the exception of the internal scrap arising in the finishing plants, has an unknown zinc content. This is particularly true of capital scrap. A knowledge of the Zn load per converter batch would basically make it possible to identify and hive off dusts and slurries suitable for the blast furnace. This would permit separation of recyclable and non-recyclable dust fractions, which would reduce the amount of material to be land filled or processed separately. While it is in principle technically possible to study the Zn content of metal in the scrap industry, the information would not normally be very useful, as it is practically impossible to take a representative sample in normal scrap handling practice. A way must therefore be found of reliably quantifying the zinc stream from the converter, in order to be able to determine the zinc load of the dusts and slurries from waste gas purification. The evaporation behaviour of zinc can be harnessed for this purpose, as dusts highly contaminated with zinc are driven off as soon as pig iron is poured over the scrap, or during the following first minutes of blowing, so that a reliable zinc analysis should be possible. The task is to develop a method of detecting zinc in the flue dust of the converter deduster. The objective is to measure the Zn content above a threshold value reliably throughout the process, in order to use this information to separate low-zinc from high-zinc dust fractions.
In dem vorgeschlagenen Projekt sollen fuer Solarzellen Duennschichten aus grobkoernig polykristallinem Silizium in einem Niedertemperaturprozess auf Glas, Stahlblech oder auf metallisiertem Glas hergestellt werden. Hierfuer ist ein dreistufiges Verfahren vorgesehen. In der ersten Stufe soll mit einem plasmainduzierten CVD-Prozess eine 10 nm bis 500 nm Dicke Schicht aus amorphem Silizium abgeschieden werden. Im zweiten Schritt soll diese durch Laserbestrahlung kristallisiert werden, wobei Korngroessen von ca. 100 mym angestrebt werden. In einem dritten Schritt soll auf dieser Primaerschicht durch epitaktisches Wachstum weiteres Silizium abgeschieden werden, bis die fuer kristalline Solarzellen erforderliche Schichtdicke (max. 50 mym) erreicht ist. Die Substrattemperaturen sollen waehrend des gesamten Prozesses 500 Grad Celsius nicht ueberschreiten.
Ziel des Vorhabens ist, durch eine systematische Optimierung leichte und steife Stahlblech-/Aluminiumschaum-Verbunde zu entwickeln und diese bezueglich ihres Werkstoffverhaltens zu charakterisieren; innovative, rein metallische recycelbare Leichtbauweise; Herstellung durch Walzplattieren und Schaeumen; Sandwichverbunde bis ueber DIN A 3 oder 2 m x 160 mm bei einer Dichte von 0,7 - 2,0 g/Mym3; gute strukturelle und funktionelle Eigenschaften; positive Resultate zu Umformbarkeit, Schweissen, Korrosionsverhalten; erste Vorschlaege zu Anwendungen, bisher keine technische Nutzung.