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Abstract

This article presents the results of studies into the phase and chemical composition of blast furnace slag in the context of its reuse. In practice, blast furnace slags are widely used in the construction industry and road building as a basis for the production of, for example, cements, road binders and slag bricks. T hey are also used in the production of concrete floors, mortars, and plasters. Blast furnace slag is mainly used as a valuable material in the production of hydraulic binders, especially cement that improves the mechanical properties of concretes.
The favorable physical and mechanical properties of slags, apart from economic aspects, are undoubtedly an asset when deciding to use them instead of natural raw materials. In addition to the above, there is also the ecological aspect, since by using waste materials, the environmental interference that occurs during the opencast mining of natural aggregates is reduced. S pecifically, this means waste utilization through secondary management.
However, it should be kept in mind that it is a material which quite easily and quickly responds to environmental changes triggered by external factors; therefore, along with the determination of its physical and mechanical properties, its phase and chemical composition must be also checked.
The studies showed that the predominant component of the blast furnace slag is glass which can amount up to 80%. In its vicinity, metallic precipitate as well as crystallites of periclase, dicalcium silicates and quartz can be found. With regard to the chemical composition of the slag, it was concluded that it meets the environmental and technical requirements regarding unbound and hydraulically bound mixtures. In case of the latter, in terms of its chemical composition, the slag meets the hydraulic activity category CA3. It also meets the chemical requirements for using it as a valuable addition to mortars and concretes, and it is useful in the production of CEM II Portland-composite cement, CEM III blast-furnace cement and CEM V composite cements. The blast furnace slag is a valuable raw material for cement production. Cement CEM III/C contains 81–95% of blast furnace slag in accordance with E N 197-1:2012. In 2019, the Polish cement industry used 1,939,387.7 tons of slag.
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Authors and Affiliations

Iwona Jonczy
1
ORCID: ORCID
Bartłomiej Grzesik
2
ORCID: ORCID
Andrzej Norbert Wieczorek
1
Anna Gerle
3
Paweł Nuckowski
4
Marcin Staszuk
4
ORCID: ORCID

  1. Silesian University of Technology, Faculty of Mining, Safety Engineering and Industrial Automation, Gliwice, Poland
  2. Silesian University of Technology, Faculty of Civil Engineering, Gliwice, Poland
  3. Łukasiewicz Research Network, Institute of Ceramics and Building Materials, Refractory Materials Division in Gliwice, Poland
  4. Silesian University of Technology, Faculty of Mechanical Engineering, Gliwice, Poland
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Abstract

The cement production process is associated with the emission of dust. These are mainly CKD (cement kiln dust) and BPD (by-pass dust), classified as wastes from group 10 – Wastes from thermal processes, subgroups 10 and 13 – wastes from manufacture of cement, lime and plaster and articles and products made from them. Cement kiln dust is a waste of variable composition and properties, which makes it a difficult material to recover. The main directions of recovery presented in the world literature indicate the use of dust from cement kilns in cement, mortar and concrete production, the production of bricks and in order to improve soil quality and wastewater treatment. Factors affecting chemical and phase compositions of dust from cement kilns are the reason why each waste should be analyzed individually. The paper presents the results of the analysis of the cement kiln dust after dedusting cement kilns and two bypass dusts. Analysis of the chemical composition has shown significant concentrations of chlorine, potassium and calcium in all wastes. The content of: Si, S, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Zr, Pb, and Bi has also been confirmed. The analyzed dusts were characterized by the presence of carbonates (calcite, dolomite, and arcanite), quartz, alite, belite, sylvine, anhydrite, and portlandite in their phase composition. The leachates which were characterized by an alkaline reaction. In terms of leachability, high concentrations of chlorine ions in the analyzed dust leachates were confirmed, which significantly limits their use.

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Authors and Affiliations

Alicja Uliasz-Bocheńczyk
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Abstract

2-phase composites are often used for high demanding parts that can undergo impact loads. However, most of the papers on dynamic loading concerns layered composites. In our opinion, the impact loads are not considered thoroughly enough. Good examples of 2-phase composites are: (1) a WC/Co cermet or (2) a monolithic ceramic Al2O3/ZrO2. The WC/Co cermet is often modelled as having ductile elasto-plastic Co matrix and ideally elastic WC grains. It is because of very high crushing resistivity of the WC.

In this paper, we present an extension to earlier elaborated models ([44]) with the assumption of ideal elasticity of the grains. The new and general numerical model for high-velocity impact of the 2-phase composites is proposed. The idea of this novelty relies on the introduction of crushability of grains in the composite and thermo-mechanical coupling. The model allows for description of the dynamic response both composite polycrystals made of: (1) 2 different purely elastic phases (e.g. Al2O3/ZrO2) or (2) one elastic phase and the second one plastic (e.g. cermet WC/Co), or (3) 2 elasto-plastic phases with different material properties and damage processes. In particular, the analysis was limited to the cases (2) and (3), i.e. we investigated the WC/Co polycrystal that impacted a rigid wall with the initial velocity equal to 50 m/s.

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Authors and Affiliations

E. Postek
T. Sadowski
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Abstract

CrCuFeNi2Tix high-entropy alloys (HEAs) (x = 0.1 ~ 0.7) are prepared and studied in this paper to investigate the effect of titanium on the microstructure, phase composition, and mechanical properties of the CrCuFeNi2Tix-based system. Microstructural studies using scanning electron microscopy (SEM) and X-ray diffraction (XRD) showed that the addition of titanium could induce the formation of a body-centered cubic lattice (BCC) and intermetallic compounds (Ni3Ti) of the CrCuFeNi2Tix-based system. The practical formation of the phases meet the theory of the atomic size difference δ, mixing enthalpy ΔHmix, mixing entropy ΔSmix, valence electron concentration (VEC), and electronegativity difference Δχ. Additionally, the tensile and hardness properties of the CrCuFeNi2Tix-based system are investigated in this study. Generally, CrCuFeNi2Tix HEAs show low stiffness and good flexibility in mechanical properties. When the x value is relatively small, the HEAs show good ductility in the tensile test, which is the result of a face-centered cubic lattice (FCC) in the phase composition at this stage; when the x value becomes larger, due to the formation of the intermetallic compounds Ni3Ti, the HEAs show high hardness
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Authors and Affiliations

Long Chen
1 2
ORCID: ORCID

  1. Northwestern Polytechnical University, The School of Mechanical Engineering, Xi’an, China
  2. Shenzhen University, College of Electronics and Information Engineering, Shenzhen, China
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Abstract

The paper presents the research data on structure, phase composition, defect substructure state, and microhardness of surface layers in the piston alloy Al-10wt%Si-2wt%Cu irradiated by an electron beam with various energy densities and pulse times. An important finding to emerge from the study is that the processing by an electron beam with an energy density of 10 J/cm2 brings about slight surface melting, whereas a weak thermal impact of an electron beam hardly changes the phase composition. Once an energy density of an electron beam is set 30 J/cm2, intermetallic compounds dissolve and numerous micropores arise. Irradiating by an electron beam with an energy density of 50 J/cm2, randomly located microcracks are detected on the treated surface with no regard to a pulse time. A structure of high-speed cellular crystallization with cells from 500 to 600 nm forms in the surface layer. A thickness of the modified layer is related to a beam energy density. As a beam energy density goes up, a thickness of a high-speed cellular crystallization layer increases. Atoms of Si, Cu, Ni, as well as a small quantity of Fe and Mg are detected in the surface, in thin layers surrounding crystallization cells. In a layer 60-80 μm below the irradiated surface, in material between high-speed crystallization cells, there are Si atoms and an insignificant number of Cu atoms. An analysis of a deeper material part has shown a structure similar to the as cast alloy. A drop of microhardness – if compared with the as cast material – is reported at an energy density of 10 J/cm2 because an energy amount supplied by an electron beam to the alloy surface is insufficient for melting of the material and dissolution of the intermetallic phase. A raise of a beam energy density up to 20-50 J/cm2 causes a max increase of microhardness up to 1.13 GPa for 40 J/cm2, 50 s, and up to 1.16 GPa for 40 J/cm2, 200 s.

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Authors and Affiliations

D. Zaguliaev
S. Konovalov
Y. Ivanov
A. Abaturova
A. Leonov
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Abstract

This work deals with the characterization of structure, magnetic and mechanical properties of (FeNiCo)100-x(AlSi)x (x = 0, 5, 10, 15, 25) multicomponent alloys prepared by casting. The results of X-ray diffraction measurements, scanning electron microscopy observations and hardness and magnetic properties investigations are presented. The studies show that cast (FeNiCo)100-x(AlSi)x alloys reveal dendritic morphology and their phase composition depends on (Al + Si) content. For x ≤ 10 a face-centered cubic phase is observed, while the increase of Al and Si content results in a body-centered cubic phase formation. It leads to a fivefold increase of hardness from 88 HV to 526 HV. The investigated alloys have high magnetic induction reaching 170 emu/g, while their coercivity value is even up to 2.9 kA/m for x = 15, and strongly depends on chemical and phase composition.
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Authors and Affiliations

B. Kurowski
1
ORCID: ORCID
D. Oleszak
1
ORCID: ORCID

  1. Warsaw University of Technology, Faculty of Materials Science and Engineering, Woloska Str. 141, 02-507 Warsaw, Poland

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