Wyniki wyszukiwania - BazTech

1

Comparative performance assessment of nano-composite cathode of lmso-bscmf for low temperature solid oxide fuel cell applications

Subhashini P.V.C.K., Rajesh K.V.D.

Composites Theory and Practice

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2023

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R. 23, nr 4

235--238

EN

The development of novel cathode materials for low temperature solid oxide fuel cell (SOFC) applications is one of the significant research areas in materials engineering. In the current work, composite cathode materials were prepared by two different modes and the fuel cell performance was assessed using a gadolinium-doped ceria (GDC) electrolyte. Nanocomposite cathodes were fabricated using a lanthanum strontium manganite oxide (LSMO) powder of a 50-100 nm particle size and Ba0.5Sr0.5(Co0.2Mg0.8)0.2Fe0.8O3 (BSCMF) powder of a 1 μm particle size. The cathodes were prepared as layered composites and mixed composites. The electrochemical performance of the symmetric cells was investigated by electrochemical impedance spectroscopy (EIS) at the intermediate temperature of 700°C using air atmosphere. The cathode film coating on the electrolyte was sintered at three different temperatures (900, 950 and 1000°C) and the cell performance was assessed at 700°C. Lower polarization resistance (RP) values were recorded for the cell produced at 900°C. The RP of the nano-composite cathodes was measured as lower (2.72 Ω-cm2 for the layered composites and 1.76 Ω-cm2 for the mixed composites) compared with LSMO. Hence, the results demonstrate the potential of using an LSMO-BSCMF composite in the mixed mode as a cathode for low temperature SOFCs to achieve a lower polarization potential.

2

Electrochemical behavior and morphology of selected sintered samples of Mg65Zn30Ca4Pr1 alloy

Hrapkowicz Bartłomiej, Lesz Sabina, Drygała Aleksandra, Karolus Małgorzata, Gołombek Klaudiusz, Babilas Rafał, Popis Julia, Gabryś Adrian, Młynarek-Żak Katarzyna, Garbiec Dariusz

Bulletin of the Polish Academy of Sciences. Technical Sciences

|

2023

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Vol. 71, nr 3

art. no. e145564

EN

In order to investigate the effect of the milling time on the corrosion resistance of the Mg65Zn30Ca4Pr1 alloy, powders of the alloy were prepared and milled for 13, 20, and 70 hours, respectively. The samples were sintered using spark plasma sintering (SPS) technology at 350◦C and pressure of 50 MPa. The samples were subjected to potentiodynamic immersion tests in Ringer’s solution at 37◦C. The obtained values of Ecorr were –1.36, –1.35, and –1.39 V, with polarization resistance Rp = 144, 189, and 101 Ω for samples milled for 13, 20 and 70 h, respectively. The samples morphology showed cracks and pits, thus signaling pitting corrosion.

3

Asymetryczne reakcje pericykliczne katalizowane kompleksami magnezu

Czombik Anna

Wiadomości Chemiczne

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2022

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[Z] 76, 9-10

755--788

EN

II Group-metals, like magnesium, are one of the most widespread elements in the environment. The abundance of II-group metals in the Earth’s crust is over 108 times greater than the precious metals. For the industrial applications, the important factors are the low costs of production and higher accessibility of their compounds. This puts the spotlight on alkaline-earth metals competing with transition elements as catalysts in organic synthesis. Features of their derivatives, like mild Lewis acidity and strong Brønsted basicity enabled them to catalyze reactions where Lewis-acidactivation of the substrate is essential. In this review the emphasis was put on magnesium-catalyzed pericyclic reactions, which are recognized as one of the most important methods of new carbon-carbon or carbon-heteroatom bonds formation. Using the catalysts based on II-group metal cations and chiral ligands, a highly stereoselective conversion of achiral substrates into enantioenriched products is possible. The Mg-based catalysts have been used in Diels-Alder, ene and 1,3-dipolar additions. Described synthesis methods were characterized by high efficiency (chemical yields and enantiomeric excesses). Where applicable, the relationships between the structure of catalyst/substrates, conditions and efficiency were discussed. Just now there are a few applications, for example in synthesis of alkaloid (–)-manzacidine or antibiotic of algal origin – (–)-malyngolide.

4

Fortyfikacja magnezem napojów funkcjonalych

Szymańska Monika, Kręgiel Dorota

Przemysł Spożywczy

|

2022

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T. 76, nr 4

36--40

PL

W ostatnich 10 latach nastąpił wyraźny wzrost zainteresowania magnezem i formą jego codziennej suplementacji. To zainteresowanie ma uzasadnienie, gdyż magnez jest czwartym, pod względem zawartości, pierwiastkiem ciała człowieka, wykazującym holistyczny wpływ na funkcjonowanie całego organizmu. Niedobór magnezu może powodować nie tylko stany niepokoju, zdenerwowania, lęku, zniecierpliwienia, ale także zwiększać pobudliwość mięśnia sercowego i zaburzać procesy mineralizacji kości. Dlatego suplementacja diety magnezem poprzez lub stosowanie produktów fortyfikowanych, np. napojów funkcjonalnych, może być wygodnym sposobem uzupełnienia niedoborów tego pierwiastka w organizmie człowieka. W artykule dokonano przeglądu literatury dotyczącej magnezu i jego znaczenia dla organizmu człowieka oraz zagadnień związanych z fortyfikacją napojów funkcjonalnych.

EN

In the last decade, there has been a marked increase in interest in magnesium and its daily supplementation. This interest is justified, because magnesium is the fourth element in the human body in terms of content, showing a holistic effect on the functioning of the entire organism. Magnesium deficiency can not only cause anxiety, nervousness, anxiety and impatience, but also increase the excitability of the heart muscle and disrupt bone mineralization processes. Therefore, supplementing the diet with magnesium through or using fortified products, e.g. functional drinks, can be a convenient way to supplement the deficiencies of this element in the human body. The article reviews the literature on magnesium and its importance for the human body as well as issues related to the fortification of functional drinks.

5

Zinc and Magnesium vs COVID-19

Sokołowska Barbara, Nazaruk Stanisława Katarzyna, Radzka-Pogoda Agnieszka, Henrykowska Gabriela, Borzęcki Andrzej

Polish Hyperbaric Research

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2022

|

nr 2(79)

45--52

EN

Zinc and magnesium are among the most important elements for the human body. A deficiency or excess of either of them may pose a potential threat to the homeostatic mechanisms of the body. Both elements condition the proper functioning of the immune system. Zinc and magnesium deficiency significantly reduces the body's immunity, facilitating infection with various pathogens, including SARS-COV-2 infection. In this paper, we reviewed the literature on the impact of zinc and magnesium deficiencies on the incidence and course of COVID-19.

PL

Cynk i magnez to jedne z ważniejszych pierwiastków dla organizmu człowieka. Niedobór lub nadmiar któregoś z nich może stanowić potencjalne zagrożenie dla mechanizmów homeostazy ustroju. Pierwiastki te warunkują prawidłowe funkcjonowanie układu immunologicznego. Niedobór cynku i magnezu istotnie zmniejsza odporność organizmu ułatwiając infekcje różnymi patogenami, w tym zakażenia SARS-COV-2. W pracy dokonano przeglądu piśmiennictwa obejmującego zagadnienia wpływu niedoborów cynku i magnezu na zachorowanie i przebieg COVID-19.

6

Znaczenie alotropii wybranych pierwiastków chemicznych oraz polimorfizmu ich związków

Badora Aleksandra, Celińska Magdalena, Filipek Tadeusz

Przemysł Chemiczny

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2021

|

T. 100, nr 2

168--172

PL

Wiele pierwiastków chemicznych oraz ich związków ma szerokie zastosowanie w produktach dostępnych na rynku. Są obecne zarówno w produktach żywnościowych, preparatach leczniczych, jak i w kosmetykach. Na podstawie przeglądu literatury i danych producenta dokonano analizy ich aktywności oraz potencjalnych korzyści i zagrożeń wynikających z ich stosowania. Przeanalizowano też wpływ tych substancji na środowisko naturalne.

EN

A review, with 35 refs., of chem. elements and their comps. used in foods, drugs and cosmetics. Their activity, potential benefits and risks as well as environmental impacts were taken into consideration.

7

Synthesis of Mg-based alloys with rare-earth element addition by means of mechanical alloying

Lesz Sabina, Hrapkowicz Bartłomiej, Gołombek Klaudiusz, Karolus Małgorzata, Janiak Patrycja

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e137586

EN

Magnesium-based alloys are widely used in the construction, automotive, aviation and medical industries. There are many parameters that can be modified during their synthesis in order to obtain an alloy with the desired microstructure and advantageous properties. Modifications to the chemical composition and parameters of the synthesis process are of key importance. In this work, an Mg-based alloy with a rare-earth element addition was synthesized by means of mechanical alloying (MA). The aim of this work was to study the effect of milling times on the Mg-based alloy with a rare-earth addition on its structure and microhardness. A powder mixture of pure elements was milled in a SPEX 8000D high energy shaker ball mill under an argon atmosphere using a stainless steel container and balls. The sample was mechanically alloyed at the following milling times: 3, 5, 8 and 13 h, with 0.5 h interruptions. The microstructure and hardness of samples were investigated. The Mg-based powder alloy was examined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and using a Vickers microhardness test. The results showed that microhardness of the sample milled for 13 h was higher than that of those with milling time of 3, 5 and 8 h.

8

Mechanical alloying of Mg-Zn-Ca-Er alloy

Hrapkowicz Bartłomiej, Lesz Sabina, Kremzer Marek, Karolus Małgorzata, Pakieła Wojciech

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e137587

EN

Magnesium-based materials constitute promising alternatives for medical applications, due to their characteristics, such as good mechanical and biological properties. This opens many possibilities for biodegradable materials to be used as less-invasive options for treatment. Degradation is prompted by their chemical composition and microstructure. Both those aspects can be finely adjusted by means of proper manufacturing processes, such as mechanical alloying (MA). Furthermore, MA allows for alloying elements that would normally be really hard to mix due to their very different properties. Magnesium usually needs various alloying elements, which can further increase its characteristics. Alloying magnesium with rare earth elements is considered to greatly improve the aforementioned properties. Due to that fact, erbium was used as one of the alloying elements, alongside zinc and calcium, to obtain an Mg₆₄Zn₃₀Ca₄Er₁ alloy via mechanical alloying. The alloy was milled in the SPEX 8000 Dual Mixer/Mill high energy mill under an argon atmosphere for 8, 13, and 20 hours. It was assessed using X-ray diffraction, energy dispersive spectroscopy and granulometric analysis as well as by studying its hardness. The hardness values reached 232, 250, and 302 HV, respectively, which is closely related to their particle size. Average particle sizes were 15, 16, and 17 μm, respectively.

9

The role of hydrogen gas buble in hydrophobic properties in mixed micro layer (Al2O3+Mg)

Subagyo R., Wardana I. N. G., Widodo A., Siswanto E.

Archives of Materials Science and Engineering

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2020

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Vol. 105, nr 1

5--16

EN

Purpose: To find out more about the role of hydrogen gas bubbles in improving the hydrophobic nature of a layer, especially in the layers of microparticles Alumina (Al2O3) with Magnesium (Mg). Design/methodology/approach: The method used is an experimental method by first conducting the SEM-Edx test, testing the content of the elements in the waxy layer and observing the topographic shape on the surface of the taro leaves. Then prepare a mixture of Alumina micro particles with Magnesium to investigate the hydrophobicity of the taro leaves. The mixed presentations between Alumina and Magnesium are: (0, 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%). Findings: The results of this study found three conditions of the Alumina and Magnesium mix layer when in contact with a droplet, namely: Hydrophobic conditions occur when the surface structure of the rough mixed micro layer forms micro crevices, then bubbles of hydrogen gas fill it to form trapped gases. When droplets come in contact with the surface of the mixed layer the effect of the gas being trapped is very effective at creating hydrophobic properties. While the transition conditions occur when more and more hydrogen gas bubbles along with the increasing percentage of Mg and the opposite occurs in micro particle fissures. Bubbles fill the micro-gap space fully so that the tops of the micro particles are covered by bubbles. This causes the droplet surface tension to weaken, so the droplet contact angle decreases. Furthermore, hydrophilic conditions occur when the micro gap is getting narrower as the percentage of Mg increases and the formation of hydrogen gas bubbles increases. The high level of bubble density in the micro gap closes the peaks of the micro particles, which results in the surface tension of the droplet getting weaker. In this weak surface tension condition, the hydrogen bubble can break through the droplet surface tension and change its hydrophobic nature to hydrophilic. Research limitations/implications: This research is limited to the hydrophobicity of Alumina and Magnesium materials, mainly to investigate the role of hydrogen gas in supporting the hydrophobic nature of taro leaves (Colocasia esculenta). Practical implications: The practical implication in this study is the use of hydrophobic membranes which are widely applied to filtration. Originality/value: Discovered the composition of a membrane mixture of Alumina (Al2O3) and Magnesium (Mg) to create hydrophilic and hydrophobic conditions.

10

Analysis of the nitrogen and magnesium doses effects of two cultivars of maize (Zea mays L.) using multivariate methods

Bocianowski Jan, Cichocki Marek, Szulc Piotr, Tratwal Anna, Nowosad Kamila, Kobus-Cisowska Joanna

Journal of Research and Applications in Agricultural Engineering

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2019

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Vol. 64, nr 3

4--9

EN

The paper presents the results of a multivariable research regarding the evaluation of variability of selected quantitative traits in two cultivars of maize (Zea mays L.): ES Palazzo and ES Paroli after using doses of nitrogen and magnesium. The study took into account 12 traits recorded for three years (2009-2011). The statistical analysis of obtained results was conducted using multivariable methods: multivariate analysis of variance, canonical variable analysis and Mahalanobis distances. The most varied objects were A4B1C2 and A1B2C1 (in 2009), A4B1C1 and A2B2C2 (in 2010), A4B2C1 and A1B2C2 (in 2011) and A4B2C1 and A1B2C2 (for all three years). The most similar objects (with regard to the 12 traits analyzed together) were A4B2C2 and A3B2C2 (in 2009), A4B2C2 and A3B1C2 (in 2010), A2B2C2 and A2B1C2 (in 2011) and A4B2C2 and A3B2C2 (for all three years). The Mahalanobis distances between particular objects in particular years of observations were positive and statistically significantly correlated.

PL

W pracy przedstawiono wyniki badania zmienności wybranych cech ilościowych dwóch odmian kukurydzy (Zea mays L.): ES Palazzo i ES Paroli po zastosowaniu różnych dawek azotu i magnezu stosując wielowymiarowe metody statystyczne. W badaniach wzięto pod uwagę 12 cech ilościowych obserwowanych w doświadczeniu trzyletnim przeprowadzonym w latach 2009-2011. Analiza statystyczna uzyskanych wyników została przeprowadzona z użyciem metod wielowymiarowych: wielozmiennej analizy wariancji, analizy zmiennych kanonicznych i odległości Mahalanobisa. Najbardziej zróżnicowanymi obiektami były A4B1C2 i A1B2C1 (w 2009), A4B1C1 i A2B2C2 (w 2010), A4B2C1 i A1B2C2 (w 2011) oraz A4B2C1 i A1B2C2 (dla wszystkich trzech lat). Natomiast, najbardziej podobnymi obiektami (pod względem wszystkich 12 cech traktowanych łącznie) były A4B2C2 i A3B2C2 (w 2009), A4B2C2 i A3B1C2 (w 2010), A2B2C2 i A2B1C2 (w 2011) oraz A4B2C2 i A3B2C2 (dla trzech lat). Odległości Mahalanobisa pomiędzy poszczególnymi obiektami w poszczególnych latach prowadzenia obserwacji były dodatnio i istotnie statystycznie skorelowane. Słowa

11

Characterization of Ca50Mg20Zn12Cu18 Alloy

Hrapkowicz B., Lesz S.T.

Archives of Foundry Engineering

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2019

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iss. 1

75--82

EN

The Ca50Mg20Zn12Cu18 was assessed with different methods in order to characterize its basic characteristics, and to determine whether the amorphous alloy of such composition would be applicable as an implant material. The XRD analysis was conducted to conclude the structure of the initial material. The Ca50Mg20Zn12Cu18 ingot sample demonstrates crystalline structure containing two main intermetallic phases, however as-cast plates show features of an amorphous material, revealing the characteristic amorphous halo on the x-ray patterns. It was confirmed by the scanning electron microscopy method and fracture images revealing chevron pattern morphology with shell type fracture. Corrosion resistance, was studied using the potentiostatic analysis. The amorphous samples show higher resistance than the crystalline one. Post corrosion surface of the Ca50Mg20Zn12Cu18 alloy exhibits high concentration of magnesium and calcium hydroxides, forming the globular structures in large aggregates of spherical units.

12

Characteristics of production methods of aluminium and magnesium matrix composite castings

Gawdzińska K., Łapawa R., Szymanski P., Bejger A., Nozdrzykowski K.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

|

2018

|

z. 90 [298], nr 3

285--296

EN

Light metal (aluminium and magnesium) matrix composites in particular are being increasingly used in various kinds of transportation vehicles. The properties of final products are closely related to the employed production technology. This paper presents a brief review of the technologies used in aluminium and magnesium matrix composite casting, with a focus on the risks and benefits of each technology.

PL

Kompozyty metalowe, a w szczególności o osnowie z metali lekkich (jak aluminium i magnez), są obecnie coraz częściej stosowane w różnego typu środkach transportu. Właściwości gotowych wyrobów są ściśle powiązane z ich technologią wytwarzania. W niniejszej pracy przedstawiono krótki opis technologii odlewów kompozytowych o osnowie aluminiowej i magnezowej, koncentrując się na wadach i zaletach poszczególnych technologii.

13

Plazmowe utlenianie elektrolityczne jako metoda ochrony przed korozją magnezu i jego stopów

Florczak Ł., Nawrat G., Kwolek P., Sieniawski J., Sobkowiak A.

Przemysł Chemiczny

|

2018

|

T. 97, nr 12

2145--2153

PL

Przedstawiono charakterystykę fizycznych i chemicznych właściwości magnezu i jego stopów, proces ich korozji i metody jej przeciwdziałania. Szczegółowo opisano proces plazmowego utleniania elektrolitycznego ze względu na jego szerokie zastosowanie do wytwarzania warstw ochronnych na magnezie i jego stopach. Przedstawiono podstawy teoretyczne tego procesu oraz omówiono wpływ elektrycznych i chemicznych parametrów na właściwości użytkowe wytwarzanych warstw konwersyjnych.

EN

A review, with 188 refs., of physical and chem. properties of the title metals, their susceptibility to corrosion as well as impact of chem. and elec. parameters of the process on the quality of the obtained protective layers.

14

Amorphous materials in the production of new implants

Kiljan A., Liptakova T.

Production Engineering Archives

|

2018

|

Vol. 18

50--53

EN

Amorphous materials based on magnesium are new materials for potential biomedical application, especially for new implants, as they bear resemblance to titanium implants. Mg66Zn30Ca4 alloy has specific properties, especially mechanical and corrosive, therefore, it has biomedical application as its properties are better than that of other materials. The following paper describes amorphous alloy based on magnesium, properties and shows how to produce amorphous samples of Mg66Zn30Ca4.

15

Próba zmiękczania wody podziemnej w procesie krystalizacji heterogenicznej w złożu fluidalnym z użyciem ługu sodowego

Markowicz P., Olsińska U.

Ochrona Środowiska

|

2018

|

Vol. 40, nr 2

51--54

PL

Twardość wody, powodowana obecnością jonów wapnia i magnezu, nie jest czynnikiem stanowiącym zagrożenie zdrowia konsumentów. Jednakże woda o podwyższonej twardości może nie być akceptowana przez odbiorców z powodu wytrącania się osadów i wówczas zmniejszenie twardości wody staje się koniecznym warunkiem komfortu jej użytkowania. Zmiękczanie wody może być prowadzone na drodze chemicznej lub fizycznej, w takich procesach jak wymiana jonowa, procesy membranowe, strącanie chemiczne czy krystalizacja. Możliwości zmiękczania wody podziemnej metodą krystalizacji heterogenicznej, łącznie z usuwaniem związków żelaza i manganu, określono doświadczalnie w stacji pilotowej, której podstawowym elementem był reaktor ze złożem fluidalnym z piasku kwarcowego, pełniącego rolę zarodków krystalizacji węglanu wapnia. Twardość ogólna wody podziemnej wynosiła 160÷166 gCaCO3/m3, zawartość żelaza – 0,44÷0,66 gFe/m3, a manganu – 0,16÷0,23 gMn/m3. Do zmiękczania wody zastosowano ług sodowy (NaOH), dawkowany w ilości odpowiadającej w przybliżeniu dawce stechiometrycznej wymaganej do usunięcia jonów wapnia. W badaniach pilotowych nad zmiękczaniem wody podziemnej w procesie krystalizacji heterogenicznej z użyciem ługu sodowego wykazano możliwość zmniejszenia twardości ogólnej wody o 40% przy użyciu dawki NaOH o połowę mniejszej od stechiometrycznej. Stwierdzono selektywne usuwanie jonów wapnia, przy stosunkowo niewielkim zmniejszeniu zawartości jonów magnezu, a także jednoczesne usunięcie z wody związków żelaza i manganu. Przeprowadzona analiza porównawcza procesu krystalizacji heterogenicznej i nanofiltracji potwierdziła przydatność obu procesów do zmniejszania twardości wody wprowadzanej do systemu dystrybucji oraz jej negatywnych skutków.

EN

Hardness of water caused by calcium and magnesium salts does not pose any health risk to consumers. However, harder water may not be widely accepted due to the build-up of scale deposits. Hence, hardness reduction becomes a critical factor of water usage comfort. Water hardness may be reduced via chemical or physical processes, such as ion exchange, membrane processes, stripping or crystallization. Potential application of heterogeneous crystallization to groundwater hardness reduction, including iron and manganese removal, was determined empirically at the pilot station with fluidized bed reactor of arenaceous quartz, serving as a nuclei of crystallization for calcium carbonate. Total hardness of groundwater was ranging from 160 to 166 gCaCO3/m3, the iron content – from 0.44 to 0.66 gFe/m3, while the manganese – from 0.16 to 0.23 gMn/m3. Sodium hydroxide (NaOH) was used for the purpose of water softening, at the amount close to the stoichiometric dose required for the calcium ion removal. Pilot studies on groundwater softening using the heterogeneous crystallization with sodium hydroxide revealed a possibility to reduce the total water hardness by 40% at the half stoichiometric point. Selective calcium ion removal was demonstrated with relatively small reduction in magnesium content. Iron and manganese cations were co-removed. A comparative analysis of heterogeneous crystallization and nanofiltration confirmed suitability of the both processes for hardness reduction of water entering the distribution system and elimination of its adverse effects.

16

Effect of texture on deformation mode in magnesium and AZ61 alloy

Sułkowski B.

Metallurgy and Foundry Engineering

|

2018

|

Vol. 44, no. 2

91--100

EN

The effect of the initial texture on the deformation mode and mechanical properties was studied in magnesium and its AZ61 alloy. Both materials had a very similar initial texture. Two cases were investigated: samples with a texture where the basal slip system was blocked, and samples having a texture where the basal slip system was allowed to activate. The samples were deformed by compression at room temperature at a strain rate of 10−3 s−1. It was found that the initial texture had a very strong impact on the deformation mode in magnesium; however, there was no effect of the initial texture on the deformation mode in the case of AZ61. The investigations were compared to simulations of texture evolution using the Taylor model. From the simulations, the Taylor factor and slip system activity were obtained. It was found that, in the case of magnesium, twinning or slip (both basal and non-basal) are the two main deformation modes, while in the case of AZ61, slip is the only main deformation mechanism despite the initial texture. The impact of the initial texture is discussed in more detail in the present study.

PL

W pracy badano wpływ początkowej tekstury na mechanizmy deformacji i właściwości mechaniczne magnezu i stopu magnezu AZ61. Zbadano dwa przypadki: próbki, w których bazalny system poślizgu został zablokowany, oraz próbki, w których bazalny system poślizgu mógł być aktywowany. Próbki odkształcano przez ściskanie w temperaturze pokojowej z prędkością odkształcania 10-3 s-1. Stwierdzono, że początkowa tekstura miała bardzo silny wpływ na sposób deformacji magnezu; jednak w przypadku AZ61 nie zauważono podobnego efektu wpływu początkowej tekstury na właściwości mechaniczne. Badania porównano z symulacjami ewolucji tekstury za pomocą modelu Taylora. Z symulacji uzyskano współczynnik Taylora i aktywności systemów poślizgu. Stwierdzono, że w przypadku magnezu, w zależności od początkowej tekstury, poślizg (zarówno w bazalnym systemie, jak i niebazalnych systemach poślizgu) oraz bliźniakowanie są dwoma głównymi mechanizmami deformacji, natomiast w przypadku AZ61 głównym mechanizmem deformacji, pomimo początkowej tekstury, jest tylko poślizg.

17

Carbon fibre reinforced wheel for fuel ultra-efficient vehicle

Wilczynski A., Bartczak M., Siczek K., Kubiak P.

Mechanics and Mechanical Engineering

|

2018

|

Vol. 22, nr 4

1419--1437

EN

Due to municipal policies that are about to be legislated in many cities around the world, it may occur that habitants will be forced to commute in ultralight urban low-consuming cars. This paper covers the research concerning the innovative design, manufacturing method and the test of the wheel for such a vehicle. The design guidelines were as follows: elevated rigidity and durability, reduced weight and ease to adapt different types of hubs and powertrains. This was achieved by determining the forces acting on the wheel, examination of the characteristics of the possible materials and performing static finite element analysis simulations that were aimed to reveal stresses distribution and presumable failure points. Afterwards, the carbon fiber reinforced polymer disc wheel was manufactured and tested to compare the empirical deformations with the results of the simulations. The results proved that this type of wheel can be successfully used in ultralight passenger vehicle. The predicted weight reduction of such a wheel, in comparison to the wheels available on the market, may be about 40% due to using carbon fibre reinforced polymer and new, innovative solution - the magnesium hub, instead of aluminum, that is known to damp the vibration more efficiently and is easier to create a strong bond with the wheel.

18

Soybean seedlings enriched with iron and magnesium - impact on germination, growth and antioxidant properties

Chmielowska-Bąk J., Zinicovscaia I., Frontasyeva M., Milczarek A., Micheli S., Vysochanska M., Deckert J.

Ecological Chemistry and Engineering. S

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2018

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Vol. 25, nr 4

631--641

EN

Iron (Fe) and magnesium (Mg) deficiency in human diets is a widespread problem observed in various regions of the world. Insufficient Fe uptake results in the development of iron dependent anaemia and depressed physical and intellectual performance. In turn Mg deficiency is associated with alterations in neuromuscular and cardiovascular systems. An emerging alternative to traditional supplementation of these elements in the form of pills, liquids or effervescent tablets, is introduction of fortified food products. In present study we show that preincubation of soybean seeds in Fe and Mg solutions leads to elevated content of these elements in the seedlings. Importantly the pretreatment did not affect germination rate, seedlings growth or, with an exception of Fe supplementation at highest concentration, antioxidant capacity. The obtained results indicate that preincubation of seeds in Fe and Mg solutions may be a promising method of obtaining enriched soybean sprouts.

19

Wpływ domieszek kilku metali na właściwości krzemianu trójwapniowego

Jelito E.

Cement Wapno Beton

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2018

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R. 21/83, nr 3

182--194

PL

W pracy przedstawiono wyniki badań wpływu dodatków ZnO, MgO, Al2O3, Cr2O3 i 2% MgO + 2% Al2O3, odpowiadający syntetycznemu alitowi. Największą wytrzymałość miał zaczyn z C3S zawierający cynk, po 28 dniach z dodatkiem 2% ZnO; wynoszącą 101 MPa. Znacznie mniejszą wytrzymałość miały próbki z dodatkiem Al2O3, a najmniejszą miał zaczyn z C3S + 1% Cr2O3. Na drugim miejscu po cynku lokuje się "syntetyczny" alit, który zapewnia dużą wytrzymałość po 1 i 2 dniach, a taką samą jak 3% dodatek ZnO po 7 dniach. Dobrą wytrzymałość daje także dodatek 2% MgO, z wyjątkiem krótkich czasów dojrzewana. Mikrokalorymetria wykazała, że występuje dobra korelacja ciepła hydratacji z wytrzymałością, aczkolwiek nie ma korelacji okresu indukcji, który jest długi w przypadku cynku, natomiast zaczyn C3S + ZnO ma po 1 dniu dużą wytrzymałość. Badania mikrostruktury zaczynów wykazały, że cynk nie jest równomiernie rozmieszczony w kryształach krzemianu trójwapniowego, są kryształy, które w ogóle nie zawierają cynku. Spowodowało to podobne zróżnicowanie w fazie C-S-H; faza ta zawierająca cynk ma nietypową morfologię.

EN

In the paper the experimental results of the influence of ZnO, MgO, Al2O3 Cr2O3 and 2% MgO + 2%Al2O3 addition to C3S, the last one corresponding to synthetic alite, on the properties of these solid solutions are presented. The highest compressive strength had the paste of C3S + ZnO, after 28 days equal to 101 MPa. Significantly lower strength had the specimens with Al2O3 and the lowest the paste of C3S+ 1% Cr2O3. On the second place after zinc was the paste of “synthetic” alite which had the high strength after 1 and 2 days and the same as the sample of C3S + 3% ZnO after 7 days. Good strength the specimens of C3S + 2% MgO are also assuring, with exception of the short period of curing. The microcalorimetry had shown the good correlation of the heat of hydration with strength, however, there was no correlation of the induction period time with early strength of the paste from C3S + ZnO. Simultaneously the observation of the pastes microstructure had shown that zinc is not uniformly distributed among the tricalcium silicate crystals; there are particles which do not contains zinc. The similar differentiation of C-S-H phase was observed; this phase containing zinc has the untypical morphology.

20

Mechanical and wear behaviour of the Al-Mg-nano ZrC composite obtained by means of the powder metallurgy method

Sankaranarayanan G., Balaji A. N., Velmanirajan K., Gangatharan K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2018

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Vol. 66, nr 5

729--735

EN

This work concentrates on the impact and contribution of zirconium carbide (ZrC) and magnesium to the mechanical and tribological properties of aluminium matrix composites. Distinctive weight portions of zirconium carbide, containing fixed weight fractions of magnesium and strengthening aluminium composites, were prepared utilising the entrenched cold-press sintering technique used in powder metallurgy. The uniform powder mixture was obtained by using planetary ball milling and it was then observed by using the scanning electron microscope technique. The hardness of the hybrid composite increased along with increase in the amount of the ZrC particle. The wear losses of sintered Al-Mg-ZrC composites were explored by directing sliding tests in pin-on-disc equipment. Hybridisation of reinforcements also decreased the wear loss of the composites at high sliding load and speed. This study reveals that the hybrid aluminium composite can be considered a unique material with high strength, low weight and wear resistance that will find their application in components to be used in the automobile and aero space engineering sectors.