Browsing by Subject "scanning electron microscopy (SEM)"

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Access status: Open Access ,
Diatomaceous rocks of the Jawornik deposit (the Polish Outer Carpathians) - petrophysical and petrographical evaluation
(Wydawnictwa AGH, 2015) Figarska-Warchoł, Beata; Stańczak, Grażyna; Rembiś, Marek; Toboła, Tomasz
Diatomites belonging to a list of raw materials used in the EU criticality assessment are essential to many industrial applications due to a unique combination of their physical properties, i.e. porous and permeable structure, high specific surface area and adsorption capacity, low density and thermal conductivity, and chemical inertness. The present study was undertaken to analyse the relationships between the pore network characteristics, petrophysical parameters, and mineralogical variability of the Lower Miocene diatomites from the Jawornik deposit (Skole Unit, the Polish Outer Carpathians, SE Poland). Five varieties of the diatomites, distinguished on the basis of the macroscopic features, i.e., colour and fracturing effects, have been investigated by SEM, chemical and XRD analysis, mercury intrusion porosimetry, helium pycnometry, and the Vickers hardness tests. Significantly differing are two varieties. The light-coloured, massive and block-forming diatomites (variety BL) consist mainly of poorly cemented siliceous skeletal remains of diatoms, and represent the rocks with high total porosity (38–43%), low bulk density (1.28–1.38 g/cm$^{3}$) and low microhardness (10.7 HV$_{0.3}$). The dark-gray silicified diatomites with a platy or prismatic splitting (variety PD) reveal obscured microfossils of diatoms and are the most compact and hard rocks (80.8 HV$_{0.3}$), with poor total porosity (17–24%) and higher bulk density (1.70–1.78 g/cm$^{3}$). The spatial distribution of the field identifiable rock varieties allows selective exploitation of the diatomites with the predictable petrophysical characteristics that define their future use.
Access status: Open Access ,
Microstructure and mechanical properties of amorphous/crystalline ductile liquid immiscible Fe-Si-B-In alloy produced by two-component melt-spinning
(2017) Ziewiec, Krzysztof; Wojciechowska, Mirosława; Mucha, Dariusz; Ziewiec, Aneta
The two-component melt-spun (TCMS) Fe₇₁₂₅Si₉₅B₁₄₂₅In₅ alloy was produced from Fe₇₅Si₁ₒB₁₅ and Fe₆₇.₅Si₉B₁₃.₅In₁ₒ alloys. The microstructure of the TCMS alloy was investigated by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). A tensile test of the alloy resulted in a tensile strength of Rm = 1040 MPa, yield strength Re= 919 MPa, total plastic elongation etot = 3.29%, and traces of plastic deformation on the surface of the Fe-Si-B-In TCMS sample. Microstructural analysis of the amorphous/crystalline composite and tensile sample free surface show the reason for the ductility of the sample in relation to the Fe₇₅Si₁ₒB₁₅ alloy.
Access status: Open Access ,
Thermal upgrading of hydrochar from anaerobic digestion of municipal solid waste organic fraction
(2022) Mlonka-Mędrala, Agata; Sieradzka, Małgorzata; Magdziarz, Aneta
Wydział Inżynierii Metali i Informatyki Przemysłowej
Solid fraction obtained from anaerobic digestion of municipal solid waste organic fraction is a waste produced in noticeable amounts, which according to circular economy concept can be upgraded to produce new, value-added products like: hydrogen rich process gas and carbon rich solid material. In this study, thermal upgrading of hydrochar by steam gasification was analysed. Raw material was obtained through hydrothermal carbonization (HTC) of digestate from anaerobic digestion of wet fraction of municipal solid waste at 200 and 230 °C, and residence time of 60 and 120 min. The further gasification step was carried out at 800 °C and the residence time was 10 min under nitrogen with a steam atmosphere. The main objective of hydrochar upgrading through steam gasification was production of carbon-rich material with developed active surface area. The study presented promising results regarding proper management of mixed wastes, which have not yet been analysed in the literature. It was noted that low temperature and residence time are favouring active surface area development. Analysis of the main gaseous products of the gasification process showed that syngas is composed mainly of $H_{2}$, $CH_{4}$, $CO_{2}$, $O_{2}$, and $CO$. The hydrogen concentration was the highest noted for hydrochar obtained at highest temperature and residence time. Analysis of the concentration of each syngas component reveals that combined treatment of digestate from anaerobic digestion through the HTC and gasification process results in $H_{2}$-rich syngas products and a high $H_{2}/CO$ ratio with parallel fair quality activated carbon.