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Abstract

W artykule zbadano możliwość wykorzystania popiołów lotnych klasy C (otrzymywanych w wyniku spalania węgla brunatnego w kotle pyłowym) i F (otrzymywanych w wyniku spalania węgla kamiennego metodą konwencjonalną) jako substratów do syntezy materiału zeolitowego z grupy filipsytu. W tym celu przeprowadzono szereg syntez hydrotermalnych z wykorzystaniem reagentów takich jak wodorotlenek sodu (NaOH) oraz bromek tetrapropyloamoniowy (TPABr). W wyniku reakcji otrzymano docelowy materiał zeolitowy, zarówno z popiołu klasy C, jak i F. Otrzymane produkty syntezy, jak też popiołowe substraty reakcji, poddano charakterystyce chemicznej i mineralogicznej. Badania wykazały, że popiół lotny powstały z węgla brunatnego i kamiennego może być substratem w reakcjach syntez zeolitu, jakim jest filipsyt. Analiza porównawcza dyfraktogramów rentgenowskich produktów z obu typów popiołów wykazała, że lepszym substratem jest popiół klasy C otrzymywany w wyniku spalania węgla brunatnego w kotle pyłowym (w reakcji syntezy otrzymano lepiej wykształcone formy zeolitowe). W pracy dokonano także analizy literaturowej potencjalnych kierunków zastosowania filipsytu w inżynierii i ochronie środowiska. Na podstawie zweryfikowanych danych stwierdzono, iż dalszym kierunkiem badań będzie analiza możliwości wykorzystania otrzymanych materiałów jako potencjalnych sorbentów amoniaku.
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Abstract

The subject of the paper is structural stability of the Zn-26 wt.% Al binary alloys doped with 2.2 wt.% Cu or 1.6 wt.% Ti addition. The structural stability of Zn-Al alloys with increased Al content is connected with stability of solid solution of zinc in aluminium α', which is the main component of these alloys microstructure. Such a solution undergoes phase transformations which are accompanied, among others, by changes in dimensions and strength properties. The structural stability of the ZnAL26Cu2.2 and ZnAl26Ti1.6 alloys was investigated using XRD examinations during long term natural ageing after casting, as well as during long term natural ageing after super-saturation and quenching. On the basis of the performed examinations it was stated that small Ti addition to the binary ZnAl25 alloy, apart from structure refinement, accelerates decomposition of the primary α' phase giving stable structure in a shorter period of time in comparison with the alloy without Ti addition. Addition of Ti in amount of 1.6 wt.%, totally replacing Cu, allows obtaining stable structure and dimensions and allows avoiding structural instability caused by the metastable ε−CuZn4 phase present in the ZnAl26Cu2.2 alloy.
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Abstract

The paper is concerned with comparing the methods for determining the ferrite content in castings from duplex stainless steels. It uses Schaeffler diagram, empirical formula based calculation, image analysis of metallographic sample, X-ray diffraction and measurement with a feritscope. The influence of wall thickness of the casting on the ferrite content was tested too. The results of the experiments show that the casting thickness of 25 or 60 mm does not have a significant effect on the measured amount of ferrite. The image analysis of metallographic sample and the measurement with the feritscope appear to be the most suitable methods. On the contrary, predictive methods, such as Schaeffler diagram or empirical formula based calculation are only indicative and cannot replace the real measurements. X-ray diffraction seems to be the least suitable measuring method. Values of ferrite content measured in such a way often deviated from the values measured by image analysis and with feritscope.
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Abstract

Equal-channel angular pressing (ECAP) was used as a technique for severe plastic deformation (SPD) on Al alloy AA3004. This technique produced fully dense materials of refined grain structure to sub-micrometer dimensions and advanced mechanical properties. The ECAP processing of samples was conducted as 1 to 4 passes through the die at room temperature. We present the results of the studied homogeneity evolution with the ECAP treatment. Furthermore, a Scanning Electron Microscope (SEM) was used for examination of the microstructure changes in samples undergone from 1 to 4 passes. The microhardness-HV increased upon each ECAP pass. The resulting micro-hardness evolution was attributed to crystalline microstructure modifications, such as the d-spacing (studied by X-ray Diffraction-XRD) depending on the number of ECAP pressings. The microcrystalline changes (grain refining evaluated from the Scanning Electron Microscopy – SEM images) were found to be related to the HV, following the Hall-Petch equation.
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Abstract

Zinc is present in electric arc furnace dust (EAFD) mainly in two basic minerals, namely as franklinite ZnFe2O4 and/or zincite ZnO. While zincite is relatively reactive and easily treatable, franklinite is considerably refractory, which causes problems during EAFD processing. In this work EAFD containing 18.53% Zn was leached in water solution of ammonium carbonate. This leaching solution selectively leaches zincite, while franklinite is refractory and stable against leaching in this case. The temperature dependence of zinc leaching from EAFD was studied and the activation energy EA was determined by two methods: 1.) classically based on zinc chemical analyses from the leaching solution and 2.) by using of X-Ray diffraction qualitative phase analyses of leaching residues. The determined values of activation energies 37.41 and 38.55 kJmol–1 match perfectly, which show the excellent possibility of using X-Ray diffraction toward the study of leaching kinetics at properly chosen experimental conditions. The important result is the determination of the amount zincite and franklinite in EAFD, which is not possible by using of classical chemical methods.
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