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1

Characterization of Al 6061/Al2O3/SiC composites with cerium oxide: corrosion analysis and microstructural insights

Sharma Vipin Kumar, Kumar Pardeep, Kumar Dinesh, Chalisgaonkar Rupesh, Akhai Shalom

Composites Theory and Practice

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2024

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R. 24, nr 1

49--56

EN

CeO2) is incorporated, employing electrochemical analysis and scanning electron microscopy (SEM) techniques. This study investigated the impact of cerium oxide on the corrosion behavior and assessed the hydrophobic properties of the composite surface in corrosive environments using contact angle measurements. The experimental methodology comprised several key components, like the selection of specific materials, the production of hybrid composites by the stir casting technique, the analysis of corrosion using the potentiodynamic polarization method, and the characterization of surface wettability. The metallographic analysis of the composites provided insights into the impact of various reinforcements on the microstructural properties. The incorporation of cerium oxide served to mitigate agglomeration and augment grain refinement within the composites. The utilization of potentiodynamic polarization analysis revealed enhanced corrosion resistance in hybrid composites containing cerium oxide in comparison to the Al 6061 alloy. The corrosion current density exhibited a decrease as the content of CeO2 increased. The findings indicate that cerium oxide can effectively prevent corrosion in aluminum hybrid, composites. These composites show potential for use in corrosion-prone applications.

2

Wpływ nanocząstek tlenku ceru na aktywność powierzchniową surfaktantu płucnego

Kondej D., Sosnowski T. R.

Rocznik Ochrona Środowiska

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2016

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Tom 18, cz. 2

146--157

EN

In recent years there has been an intensive development of industries that use or produce materials in the nano scale. Nanomaterials contribute to the improvement of the product parameters, but when inhaled can also negatively affect the human body. The aim of the study was to investigate the effect of cerium oxide nanoparticles on the surface activity of pulmonary surfactant (PS) forming a thin film separating the inhaled air from the alveolar epithelium. Three types of cerium oxide powders were used (Sigma-Aldrich): C1 having a particle size smaller than 25 nm, C2 having a particle size smaller than 50 nm, and for comparison purposes C3 having a particle size smaller than 5 µm. Measurement of specific surface area was carried out using a Gemini 2360 surface area analyzer (Micromeritics, USA). The effect of cerium oxide nanoparticles on the surface activity of PS was studied using DeltaPi microtensiometer (Kibron Inc., Finland). Reconstituted animal surfactant preparation (Beractantum; Abbott Laboratories, France) recommended in states of deficiency of endogenous PS in newborn premature infants, was used as model PS. The tests were carried out at different particle concentrations (ranging up to 1 mg/ml) prepared with the constant concentration of the surfactant solution (1.25 mg phospholipids/ml). The study showed that in all the analyzed cases, the presence of cerium oxide particles caused an increase in surface pressure (lowering of the surface tension) at the liquid-air interface. It was found that the intensity of these changes depends on the particle size, specific surface area and the particle concentration. With the increase in concentrations of the particles in the model surfactant suspension, a greater difference in surface pressure/tension was observed with respect to the initial value. The largest increase in surface pressure (6.4 ± 1.1 mN/m) was observed in the presence of cerium oxide nanoparticles C1, which were characterized by the smallest dimensions (smaller than 25 nm) and the largest surface area (33.3 m2/g). The results show that cerium oxide nanoparticles may have an influence on the surface activity of pulmonary surfactant in vivo and adversely affect the functioning of the human respiratory system.

3

Composite Ag-La0.6Sr0.4Co0.8 Fe0.2O3-σ cathode material for solid oxide fuel cells, preparation and characteristic

Mosiałek M., Tatko M., Dudek M., Bielańska E., Mordarski G.

Archives of Metallurgy and Materials

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2013

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Vol. 58, iss. 4

1341--1345

EN

Composite cathodes Ag-La0.6 Sr0.4 Co0.2 Fe0.8O3-σ were obtained by two different procedures. In the first procedure porous La0.6 Sr0.4 Co0.2 Fe0.8O3-σ (LSCF) matrix was prepared by sintering the LSCF paste, the matrix was then saturated with AgNO3 solution and sintered again. Introduced silver crystalized in the form of 10 nm crystallites in the whole LSCF matrix. In the second procedure the paste of silver powder was deposited on the surface of electrolyte and dried. The layer of silver paste was then covered by a layer of the LSCF paste and sintered at 850°C. The following cells were tested: H2|Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm0.2O1.9LSCF|O2, H2|Ni-Ce0.8Gd0.2 O1.9|Ce0.8 Sm0.2 O1.9 |LSCF-Ag|O2 and H2 |Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm0.2O1.9|Ag|LSCF|O2. Introduction of silver interlayer between cathode and electrolyte increased output power by 18-28% whereas introduction of metallic silver into porous LSCF caused increase in power by 14-18%.

PL

Kompozytowe katody Ag-La0.6 Sr0.4 Co0.2 Fe0.8O3-σ wykonano dwoma sposobami. W pierwszej metodzie otrzymano poro- watą matrycę La0.6 Sr0.4 Co0.2 Fe0.8O3-σ (LSCF) poprzez wyprażenie pasty LSCF, następnie nasączono ją roztworem AgNO3 i ponownie wyprażono. Wprowadzone srebro wykrystalizowało w postaci 10 nm krystalitów w matrycy LSCF. W drugiej metodzie na powierzchni elektrolitu położono pastę srebrną a po wysuszeniu pastę LSCF i wyprażono w 850°C. Testowano następujące ogniwa H2|Ni-Ce0.8Gdo.2O1.9|Ce0.8Sm0.2O1.9LSCF|O2, H2|Ni-Ce0.8Gd0.2 O1.9|Ce0.8 Sm0.2 O1.9 |LSCF-Ag|O2 and H2 |Ni-Ce0.8Gd0.2O1.9|Ce0.8Sm0.2O1.9|Ag|LSCF|O2. Wprowadzenie warstwy srebra pomiędzy katodę a elektrolit podniosło moc ogniwa o 18-28% podczas gdy wprowadzenie srebra do porowatego LSCF spowodowało wzrost mocy o 14-18%.

4

Charakterystyka spektrofotometryczna szkieł odbarwianych cerem i neodymem.

Kokoszka J., Cholewa-Kowalska K., Łączka M.

Szkło i Ceramika

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2007

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R. 58, nr 2

38-42

PL

W pracy oceniono, przy pomocy pomiarów spektrofotometrycznych, efektywność procesu odbarwiania związkami ceru i neodymu szkieł wytopionych z piasków szklarskich o zawartościach Fe2O3 od 0,008-0,05% wag. Wykazano, że zastosowanie mieszanki Nd2O3+CeO2 nie daje pożadanego efektu odbarwiającego przy szkłach wytopionych z piasków o małej zawartości żelaza, efekt ten jest widoczny natomiast przy piaskach silnie zanieczyszczonych żelazem - klasa IV.

EN

The aim of the present paper is the estimation of the effectiveness glass decolourisation applying cerium and neodymium compounds. In glass melting process are used various types of silica sand, with concentration Fe2O3 0,008-0,05% wt. From our results it follows the combination of Nd2O3+CeO2 is very useful for glasses obtained using silica sand with Fe2O3 concentration (class IV). In the case of glass melted with other classes of sand (I-III) the decolourisation efffects are very low.

5

Ceria-yttria-based solid electrolytes for intermediate temperature solid oxide fuel cell

Dudek M., Molenda J.

Materials Science Poland

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2006

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Vol. 24, No. 1

45--52

EN

Pure ceria and ceria-yttria solid solution powders with formula Ce1-xYxO2, where 0 < x < 0.30 were prepared by the coprecipitation-calcination method. The samples were sintered at 1250-1600 °C for 2 hours. The XRD method was used to determine cell parameters of the samples. Their electrical properties were investigated by ac impedance spectroscopy in the temperature range of 100-700 °C in air. It was found that the electrical conductivity, fracture toughness, and flexural strength of the samples increase with yttria concentration and reach a maximum for Ce0.85Y0.15O2. The obtained material seems to be a promising solid electrolyte for IT-SOFC.

6

Warstwy tlenku ceru otrzymywane metodą chemicznej syntezy z fazy gazowej

Kwatera A., Sawka A., Andreasik P., Juda W.

Inżynieria Materiałowa

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2006

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Vol. 27, nr 3

471-473

PL

Badania dotyczą syntezy cienkich warstw tlenku ceru metodą MOCVD (Metal - Organi Chemical Vapour Deposition) z użyciem organicznych związków ceru i powietrza przy obniżonym ciśnieniu. Jako podłoża stosowano rurki ze szkła kwarcowego. Ustalono wstępne warunki syntezy polikrystalicznych warstw CeO2. Zbadano mikrostrukturę otrzymanych warstw za pomocą mikroskopu skaningowego (SEM) oraz transmisyjnego (TEM). Zbadano również ich skład chemiczny. Z uwagi, że otrzymano bardzo gęste i polikrystaliczne warstwy już w temperaturze 600 stopni C przewiduje się, że mogą być one zastosowane do wytwarzania kompozytowych tlenkowych ogniw paliwowych nowej generacji w kształcie rur, które będą mogły pracować w temperaturach 600-800 stopni C.

EN

Research relates to synthesis of cerium oxide layers by MOCVD method using organic compounds of cerium and air under reduced pressure. Quartz glass tubes were used as substratem. Initial conditions for synthesis of polycrystalline cerium oxide layers were settled. Microstructure of obtained layers was investigated using scanning electron microscopy (SEM) and transmission eleccron microscopy (TEM). Their chemical composition also was examined. The layers obtainedt at 600 degree C were polycrystalline and characterized by high density. So, it seems that they‘ can be applied for production of composite solid oxide fuel cells (SOFC). It is also expected that those new SOFC’ll be able to work at temperatures of 600-800 degree C.

7

Effect of the CeO2 ingredient on the activity of a Pd-based monolithic catalyst for methane combustion

Kucharczyk B.

Environment Protection Engineering

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2006

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Vol. 32, nr 3

17-23

EN

CeO2 incorporation into Pd/Al2O3 active phase enhanced thermal resistance of the catalyst and its activity in methane combustion. The activity of the catalyst depended on the amount of CeO 2 incorporated as well as on the method of incorporation and was found to be the highest in the 0.5%Pd/0.25%CeO2/Al2O 3, 0.5%Pd/0.12%CeO2/Al2O3 and 2%Pd/0.12%CeO2/Al2O3 systems, where CeO 2 had been deposited onto the Al2O3-based washcoat. Methane conversion over such catalysts was notably higher than over 0.5%Pd/Al2O3 and 2%Pd/Al2O3. The incorporation of CeO2 into both washcoat and active layer brought about only a slight increase in the activity of the catalysts tested.

PL

Badanie aktywności katalizatorów palladowych z dodatkiem tlenku ceru(IV) podczas spalania metanu wykazało, że tlenek ten zwiększa aktywność katalizatora Pd/Al2O3. Aktywność katalizatorów zależy od sposobu wprowadzenia CeO2 i jego ilości. Najwyższą aktywność wykazują katalizatory o składzie 0,5% Pd/0,25% CeO2/Al2O3, 0,5% Pd/0,12% CeO2/Al2O3 i 2% Pd/0,12% CeO2/Al2O3, w których CeO2 naniesiono na powierzchnię warstwy pośredniej z Al2O3. Uzyskuje się na nich stopień przereagowania metanu znacznie wyższy niż na katalizatorach odpowiednio 0,5% Pd/Al2O3 i 2% Pd/Al2O3,. Wprowadzenie CeO2 do warstwy pośredniej i warstwy aktywnej katalizatora powoduje tylko niewielki wzrost jego aktywności.

8

Nanocrystalline doped zirconia and ceria films for fuel cell application

Jasiński P., Jasiński G., Petrovsky V., Anderson H., U.

Elektronika : konstrukcje, technologie, zastosowania

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2006

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Vol. 47, nr 12

14-15

EN

The preparation of dense electrolyte films for Solid Oxide Fuel Cells (SOFCs) is a crucial technological process. The method has been developed, which allows preparing 1 to 10 µm thick dense and nanocrystalline films. In this process the powder is first deposited onto the surface to provide a framework of connected particles into which the polymeric precursor impregnates to form an oxide particle/organic polymer composite film. Using this technology typical SOFCs electrolyte films, doped zirconia and ceria, were prepared. In this paper the films properties were evaluated and compared. Due to nanocrystalline nature of the films the grain boundary conductivity is a significant part of electrolyte conductivity.

PL

Przygotowanie gęstych i cienkich warstw do tlenkowych ogniw paliwowych jest złożonym procesem technologicznym. Opracowana przez nas metoda umożliwia przygotowanie gęstych i nanokrystalicznych warstw o grubości 1 ...10 µm. W metodzie tej, najpierw, z zawiesiny koloidalnej nanoszona jest warstwa połączonych cząsteczek związku tworząca szkielet, który następnie jest wypełniany z użyciem ciekłego prekursora metaloorganicznego. Z wykorzystaniem tej metody przygotowane zostały warstwy domieszkowanego tlenku cyrkonu i tlenku ceru, które typowo wykorzystywane są w tlenkowych ogniwach paliwowych jako elektrolity. W artykule porównywano właściwości elektryczne tych warstw. Z powodu nanokrystalicznej struktury warstw przewodnictwo obszarów międzyziarnowych jest dominujące.

9

Structural and optical properties of thermochromic bilayers CeO2-VO2

Saitzek S., Guirleo G., Guinneton F., Sauques L., Villain S., Aguir K., Leroux C., Gavarri J.R.

Inżynieria Materiałowa

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2004

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R. XXV, nr 3

653-655

EN

Using Radio-Frequency reactive sputtering techniques, thin films of thermochromic vanadium dioxide (presenting a insulator-metal phase transition at Tc = 68°C) were covered by a cerium dioxide layer. Cerium dioxide was chosen for its chemical stability, infrared optical transparency and strong optical absorption in the ultrafiolet range. Vanadium dioxide was first deposited on a silica substrate by Radio Frequency reactive sputtering. Then, a ceria thin film was deposited on the vanadium dioxide film by the same technique. The bilayers were characterized by X-ray diffraction measurements, scanning electron microscopy, transmission electron microscopy and ellipsometry techniques. Optical properties were studied by infrared spectroscopy. The optical properties of these bilayers are similar to optical properties observed for non-coated pure vanadium dioxide films.

10

Nanostructured pure and doped ceria catalysts for gas sensor applications

Saitzek S., Villain S., Fremy M.-A., Leroux C., Nolibe G., Gavarri J.-R.

Inżynieria Materiałowa

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2004

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R. XXV, nr 3

231-233

EN

For many years, CeO2 -based materials have been used as three-ways catalysts (TWC). They are also of great interest as solid electrolytes. It was already shown that nano-structured powders of cerium dioxide are more sensitive than micronic powders, for the detection of carbon monoxide CO or methane CH4 in air. By doping the cerium dioxide with various elements (Cu, V, Mn, ...), we try to improve the selectivity of the detection. The nanopowders of pure and doped cerium oxide were elaborated from "Sol-Gel" process. The structural characterization of these powders was carried out by X-ray diffraction and transmission electron microscopy. The atom fraction of doping element and the homogeneity of the powders were investigated by Energy Dispersive Spectrometry (EDS) microanalysis techniques. Finally, the catalytic activity was determined from (BET) adsorption techniques, spectrometry IR and electrical measurements involing a homemade device.