The study investigates the physical and chemical properties of fly ash and bottom ash from a power plant ELCHO in Chorzów, Poland. Coal combustion products generated in the process of combustion in circulating fluidized beds (CFBs) are considerably different from fly and bottom ashes obtained from dust furnaces and multi-layer ones. The composition of the iron-bearing phase in the waste of circulating fluidized bed combustion was determined using Mössbauer spectroscopy and X-ray powder diffraction (XRD) methods.
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Received 10.01.2011; published in revised form 01.03.2011 Purpose: The paper presents a structure characterization of selected Fe-based metallic glass in as-cast state. Design/methodology/approach: The studies were performed on Fe72B20Si4Nb4 metallic glass in form of ribbons. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM) methods. Mössbauer spectroscopy method was applied to comparison of structure in studied amorphous samples with different thickness (cooling rates). Findings: The XRD, TEM and Mössbauer spectroscopy investigations revealed that the studied alloy in as-cast state was amorphous. Comparison of diffraction patterns of studied samples with different thickness showed the slightly narrowing of diffraction lines. The TEM observations also revealed a changing of image contrast of glassy ribbons with increase of sample thickness. The Mössbauer spectra presented broadened six line patterns characteristic to the structural disorder of amorphous ferromagnetic materials. The hyperfine magnetic field distributions for studied sample thickness indicated the existence components corresponding to the regions with different iron concentration (an iron-rich and an iron-poor surroundings). Practical implications: The Mössbauer spectroscopy is very useful method in studying the structural environment of Fe atoms on a nearest-neighbor length scale allowing the analysis of iron-containing phases. Originality/value: The obtained examination results confirm the utility of investigation methods in analysis of microstructure in function of sample thickness.
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This study evaluated the structural changes of Al-Ni-(Fe,Cr,Cu)-Y alloys induced by different cooling states. The aim was to determine the role of Fe, Cr, and Cu addition as well as cooling rate on the structure, hardness and anticorrosion properties of crystalline and nanocrystalline Al-Ni-Y alloys. The impact of the preparation method on the structure of alloys was observed by the broadening of the X-ray diffraction peaks of the alloys in the form of plates, which indicated structure fragmentation at a high cooling rate. The TEM images showed the formation of a structure composed of homogeneously dispersed α-Al nanograins. Phase analysis performed using X-ray diffraction method and Mossbauer spectroscopy revealed that the slowly cooled master alloys were mainly composed of Al23Ni6Y4, Al10Fe2Y, and α-Al phases. The Al10Fe2Y structure was the main Fe-bearing phase in all investigated master alloys. A crystallization mechanism was proposed based on the DTA heating and cooling curves. The pitting corrosion type was identified based on morphology observations after electrochemical tests. Rapid solidification and the addition of chromium and copper improved the microhardness as well as corrosion resistance. The high increase of hardness (289 HV0.1) and corrosion resistance[...]
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