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Tytuł:
Synthesis of vanadium-enriched oxide materials via modified sol-gel route with the use of waste solutions contaminated with vanadium ions
Autorzy:
Weidner, Ewelina
Piasecki, Adam
Siwińska-Ciesielczyk, Katarzyna
Jesionowski, Teofil
Ciesielczyk, Filip
Powiązania:
https://bibliotekanauki.pl/articles/1450632.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
modified sol-gel method
zirconia
vanadium recovery
hybrid oxide materials
harmful metal ions
Opis:
In this study, the synthesis of zirconia as well as zirconia enriched with vanadium by modified sol-gel method was presented. The modification of the method was based on the replacement of the traditional basic promoter of hydrolysis, which is ammonia, with sodium hydroxide solution. The most favorable conditions for the synthesis of zirconium with a new hydrolysis promoter were selected. A comparative analysis of $ZrO_2$ obtained using various hydrolysis promoters was performed. Both materials exhibited almost the same physicochemical properties, which proves that in this case the nature of the hydrolysis promoter used in sol-gel route does not significantly affect the properties of the $ZrO_2$. Then, synthesis of $ZrO_2$/V systems was carried out using model and real solutions containing vanadium ions as hydrolysis promoters. The solutions formed after vanadium catalyst leaching were used as real solutions. The effect of vanadium concentration and the presence of impurities on the final physicochemical properties of the obtained hybrid materials were investigated via scanning electron microscopy (SEM), dynamic light scattering (DLS), energy-dispersive X-ray microanalysis (EDS), Fourier transform infrared spectroscopy (FT-IR), low-temperature nitrogen sorption (BET), thermogravimetric analysis (TGA). The analysis of the obtained results allows to state that the developed technique for the synthesis of $ZrO_2$ and $ZrO_2$/V systems, using a modified sol-gel method, enabled the production of attractive materials.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 6; 60-75
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Transition in SrZnO Laser Pulse Deposited Alloy
Autorzy:
Albrithen, H. A.
Elnaggar, M.
Ozga, K.
Szota, M.
Alahmed, Z. A.
Alanazi, A. Q.
Alshahrani, H.
Alfaifi, E.
Djouadi, M. A.
Labis, J. P.
Powiązania:
https://bibliotekanauki.pl/articles/355190.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
oxide materials
solid state alloys
structural phase transition
X-ray diffraction
scanning electron microscopy
Opis:
We have discovered a structural transition for the SrZnO alloy films from a wurtzite to a rock-salt structure, leading to a reduction in the (112̲0)/(0001) surface energy ratio. The films were grown by pulsed laser deposition using different SrO ratios, x. We have revealed that growth at a higher temperature, 750°C, resulted in a sharp 0002 peak at a low SrO content (5%), whereas growth at a higher SrO content (10%) resulted in a non-crystalline film with minute crystallites with a (112̲0) orientation. Generally the crystallinity decreased as the SrO content increased. No results obtained for the crystalline films showed any orientation of significant peaks besides the peak attributed to the (0001) plane, suggesting epitaxial growth. Optical measurements showed difference in transmission widows of alloys with different SrO percentage, and this was correlated to SrO influence on growth mode as indicated by scanning electron imaging. The studied SrZnO films, with SrO/(SrO + ZnO) ≤ 0.25, were grown by pulsed laser deposition using different SrO ratios, x. The effects of temperature and oxygen pressure during growth on the films’ structural properties were investigated. XRD results indicate that the film crystallinity was improved as the temperature and O2 pressure increased up to 650°C and 0.5 Torr, respectively.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 1; 211-216
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Związki alkoholanowe w syntezie nanomateriałów
The alkoxide compounds in the synthesis of nanomaterials
Autorzy:
John, Ł.
Sobota, P.
Powiązania:
https://bibliotekanauki.pl/articles/171978.pdf
Data publikacji:
2011
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
alkoholany metali
związki molekularne
tlenkowe materiały ceramiczne
metal alkoxides
molecular compounds
oxide ceramic materials
Opis:
Polynuclear metal alkoxides are nearly as common in today’s chemistry as any other simple inorganic complexes and constitute an interesting family of species with a very broad structural diversity (Fig. 3 and Tab. 1) [14]. These compounds form structural motifs which range from simple bimetallic complexes to very specific aggregates that result from the versatile coordinating abilities of an alkoxo and aryloxo ligands (Fig. 1). For the last few decades, there has been a growing interest in the development of the chemistry of metal alkoxides. Such interest derives from their fascinating structural chemistry, interesting catalytic properties, and a high potential for industrial utilization. The fact that most of them can generate highly pure and well-defined metal oxides (Table 4) has resulted in high research activity in chemistry of materials. Alkoxides and their derivatives, e.g. organometallics, are easily accessible and consist inexpensive compounds. Moreover, alkoxide ligands are easily removable during thermal treatment in a relatively low temperatures compare to conventional methods involving inorganic salts. Such compounds already have metal-oxygen bonds established on molecular structure. Due to these, alkoxides can generate oxide ceramics in a single step – so-called single-source precursors (SSPs) [11]. SSPs deliver appropriate metal elements of a final oxide product(s) eliminating the need to match the reaction rates required from a multicomponent mixture. All of these features made the metal oxides derived from metal alkoxides highly pure products possessing specific properties, chemical and mechanical resistance, excellent functions and shapes. The aim of this article is to serve as a guide in understanding the principles in a one step strategy for oxide ceramics using metal alkoxide compounds. It includes synthesis of alkoxides and their derivatives, the concept of SSPs strategy and design of molecular precursors for oxide ceramic materials.
Źródło:
Wiadomości Chemiczne; 2011, 65, 9-10; 839-868
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Statistical approach to the production of cement composites doped with ZnO and ZnO-based materials
Autorzy:
Klapiszewska, Izabela
Balicki, Sebastian
Wilk, Kazimiera A.
Klapiszewski, Łukasz
Ślosarczyk, Agnieszka
Powiązania:
https://bibliotekanauki.pl/articles/24085675.pdf
Data publikacji:
2023
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
cement composite
zinc oxide
hybrid materials
design of experiments
Opis:
In this study, physical and functional properties of the cement composites containing ZnO, ZnO/lignin and lignin admixtures were investigated using Response Surface Methodology (RSM). The I-optimal design based on RSM was used to assess the influence of ZnO-based doping agent, of either commercial or synthetic origin, on cement composite production in the function of average compressive strength and cost. Polynomial mathematical models were developed by RSM confronting results from the experimental design. The accuracy and precision of the utilized models established by I-optimal design were tested using Analysis of Variance (ANOVA). The first stage of formulation optimization revealed that the use of commercially available ZnO-based admixture no. 4 (ZnO-SA, supplied by Sigma Aldrich) allowed to achieve the desired results, passing all the requirements, i.e., the best microbial purity combined with reasonable cost, followed by satisfactory physical properties. In the second stage of formulation optimization, the influence of implementing the hybrid materials, i.e., ZnO-SA mixed in different proportions with lignin was evaluated. RSM revealed that doping admixture no. 3, i.e., ZnO-SA/lignin (5:1), is the best candidate, which comprised augmented functional and physical properties of the fabricated cement composite. This component exhibited the best microbial purity as well as the lowest total pore volume, followed by satisfactory physical properties. Verification of the model findings indicated considerable agreement between the predicted and experimental values. From the findings, it was confirmed that a reasonable cost-performance balance for cement composites can be achieved using ZnO-SA and ZnO-SA/lignin (5:1).
Źródło:
Physicochemical Problems of Mineral Processing; 2023, 59, 4; art. no. 168352
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hybrid ZnO/ZnO-NPs nanofibres fabricated via electrospinning
Autorzy:
Matysiak, W.
Zaborowska, M.
Powiązania:
https://bibliotekanauki.pl/articles/367311.pdf
Data publikacji:
2019
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
nanomaterials
electron microscopy
amorphous materials
zinc oxide
nanomateriały
mikroskopia elektronowa
materiały amorficzne
tlenek cynku
Opis:
Purpose: Due to the growing interest and multitude of possible applications, zinc oxide nanowires, including those doped with ZnO nanoparticles, can became, alongside carbon nanotubes, a very desirable material which use is predicted in the construction of nanogenerators, dye sensitized solar cells, optoelectronics or ultrasensitive gas detectors. Design/methodology/approach: The electrospinning process allows for low-cost and scalable production of fibrous mats with diameters from a few to several hundred nanometers. What is more, electrospinning method has gained popularity also due to its versatility, now it is possible to produce fibres from almost every known polymer and the simplicity and lack of any additional functionalization of the obtained nanomaterials. The application of the calcination process to remove the polymer matrix from the obtained nanofibres results in the creation of ceramic nanofibres. Findings: Among the existing methods for the production of ceramic nanostructures, including the hydrothermal, physical and chemical vapour deposition methods, nanolithography or molecular self-assembly, the electrospinning process creates the possibility of fabricating one-dimensional nanostructures with unprecedented properties, good quality, no additional functionalization and purification. Research limitations/implications: Due to ongoing research on the potential applications of zinc oxide nanostructures, including photovoltaics, sensorics and electronics, the most predictable behaviour and properties of ZnO nanowires characterize those nanomaterials that exhibit a periodic structure of the crystal lattice. Considering the optimization of the parameters of the method of producing ceramic zinc oxide nanowires doped with crystalline ZnO nanoparticles, it is worth analysing the thermal treatment parameters of nanofibres. Practical implications: Although amorphous structure, hybrid ZnO nanofibres could be used as humidity sensors with much higher sensing properties than crystalline ZnO nanostructures. Originality/value: Low-cost, scalable production of ceramic nanofibres for most technical applications.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2019, 94, 1-2; 5-12
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bending Strength of Composite Materials with EN AC-44200 Matrix Reinforced with Al2O3 Particles
Autorzy:
Kurzawa, J.
Kaczmar, J. W.
Powiązania:
https://bibliotekanauki.pl/articles/381132.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
composite materials
aluminium oxide particles
bending strength
materiały kompozytowe
tlenek glinu
wytrzymałość na zginanie
Opis:
There are presented results of a research on bending strength of aluminum alloy EN AC-44200 based composite materials reinforced with aluminum oxide particles. The composite materials were manufactured by squeeze casting with the liquid EN AC-44200 Al alloy of porous ceramic preforms under pressure of 100 MPa. For reinforcing of the EN AC-44200 matrix alloy, preforms made of Al2O3 particles with porosity 60, 70, 80 and 90% were applied. In relation to unreinforced EN AC-44200 base Al alloy, bending strength of composite materials increased about 10% per each 10 vol.% increase of Al2O3 particles in the matrix. The highest bending strength of over 400 MPa was reached by the materials reinforced with 30 and 40 vol.% of Al2O3 particles. Microscopic observations of fracture surfaces confirm that the particles intensively restrict plastic deformation of the alloy, which contributes to creation of a typically brittle fracture. The particles present on the crack propagation path inhibit development of microcracks initiated during bend tests. Most often, the fracture runs through interfacial matrix-particle boundaries, which is caused by brittle bridges of silica binder, present on these boundaries.
Źródło:
Archives of Foundry Engineering; 2015, 15, 1 spec.; 61-64
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reduction of Lead Oxide by Fine-Grained Carbonaceous Materials
Autorzy:
Matuła, T.
Siwiec, G.
Powiązania:
https://bibliotekanauki.pl/articles/356221.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
lead oxide
lead
fine-grained carbonaceous materials
anthracite dust
coal flotation-concentrate
reduction
thermogravimetry
Opis:
As part of the presented work, tests were carried out to check the possibility of replacing of conventional reducers used in the lead pyrometallurgical processes by cheaper, but equally effective substitutes. For research of lead oxide reduction, the following fine-grained carbonaceous materials were used, ie anthracite dust and coal flotation concentrate, as well as traditional used coke breeze for comparison. The obtained test results indicate a similar ability to reduce the lead oxide of all studied carbonaceous materials.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 647-652
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-healing epoxy/PDMS/graphene oxide nanocomposites for anti-corrosive applications
Autorzy:
Moorthi, Krishna
Saxena, Vishesh
Prasanna Sanka, R.V. Siva
Rana, Sravendra
Powiązania:
https://bibliotekanauki.pl/articles/2173438.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
corrosion
self-healing materials
PDMS
graphene oxide
coating
korozja
materiał samoleczący
tlenek grafenu
powłoka
Opis:
This study discusses the synthesis, characterization and development of self-healing nanocomposite of amino-terminated PDMS (Polydimethylsiloxane), Epoxy (EPON828 ̧ Diethylenetriamine (DETA)), and Graphene Oxide (GO). GO was prepared using a modified Hummer’s method and was incorporated into the PDMS-Epoxy composite in various ratios (0.1 wt.%, 0.3 wt.%, and 0.5 wt.%) using toluene as the dispersing medium. Fourier Transform Infrared Spectroscopy was used for confirming the presence of the designed/prepared structures, and thermo-mechanical analysis was performed to test the change in glass transition temperature and initiation temperature of self-healing process. The composite resins were coated on mild steel substrates by curing freshly prepared resins over the substrates at elevated temperatures. The corrosion behavior of mild steel in 3.5 wt.% NaCl solution before and after the coatings was studied using Tafel Electrochemical Polarization test. The self-healing properties of the materials were also studied by applying cuts on the material and letting them heal under elevated temperatures, and the results showed that the prepared coating demonstrated an effective corrosion resistance for mild steel for various marine applications
Źródło:
Chemical and Process Engineering; 2022, 43, 2; 137--145
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compressive Strength of EN AC-44200 Based Composite Materials Strengthened with alpha-Al2O3 Particles
Autorzy:
Kurzawa, A.
Kaczmar, J. W.
Powiązania:
https://bibliotekanauki.pl/articles/381782.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
compressive strength
composite materials
aluminium oxide particles
wytrzymałość na ściskanie
materiały kompozytowe
tlenek glinu
Opis:
The paper presents results of compressive strength investigations of EN AC-44200 based aluminum alloy composite materials reinforced with aluminum oxide particles at ambient and at temperatures of 100, 200 and 250oC. They were manufactured by squeeze casting of the porous preforms made of α-Al2O3 particles with liquid aluminium alloy EN AC-44200. The composite materials were reinforced with preforms characterized by the porosities of 90, 80, 70 and 60 vol. %, thus the alumina content in the composite materials was 10, 20, 30 and 40 vol.%. The results of the compressive strength of manufactured materials were presented and basing on the microscopic observations the effect of the volume content of strengthening alumina particles on the cracking mechanisms during compression at indicated temperatures were shown and discussed. The highest compressive strength of 470 MPa at ambient temperature showed composite materials strengthened with 40 vol.% of α-Al2O3 particles.
Źródło:
Archives of Foundry Engineering; 2017, 17, 2; 43-48
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Use of synthetic zeolite materials from fly ash to remove copper(II) ions from aqueous solutions
Autorzy:
Ulatowska, Justyna
Stala, Łukasz
Nowakowska, Alicja
Polowczyk, Izabela
Powiązania:
https://bibliotekanauki.pl/articles/1450167.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
fly ash
copper oxide (II)
Cu(II)
modification of fly ashes
zeolite materials
adsorption
Opis:
Water quality and waste management are two chief problems that the modern world is struggling with. Intensified development of the industry not only leads to the production of large amounts of solid waste that must be stored in landfills but can also result in contaminant emissions into the environment. Enormous quantities of ash produced from coal combustion have been a long-term problem of the industry. Literature studies show that fly ash can be used as a material to produce cheap and efficient zeolite-type adsorbents due to abundance of alumina-silicates in their composition. Fly ashes which were processed into zeolites as a result of alkaline hydrothermal treatment were obtained from two power plants in Poland (in Turów and Zgierz). The obtained zeolite materials and raw fly ash samples were characterised in terms of specific surface area, particle size distribution and density. The structure was also investigated using Fourier transform infrared spectroscopy (FTIR) in the mid- infrared wavenumber range. Two raw fly ashes and two zeolite materials were examined for their ability to remove Cu(II) ions from aqueous solutions. The results showed that the amount of adsorbed copper ions by alkaline-modified fly ash was higher than for unmodified fly ash. The ion removal efficiency is high and exceeds 95%.
Źródło:
Physicochemical Problems of Mineral Processing; 2020, 56, 6; 114-124
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bending Strength of EN AC-44200 – Al2O3 Composites at Elevated Temperatures
Autorzy:
Kurzawa, A.
Kaczmar, J. W.
Powiązania:
https://bibliotekanauki.pl/articles/382237.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
wytrzymałość
stop aluminium
materiały kompozytowe
tlenek glinu
bending strength
aluminium alloy
composite materials
aluminium oxide particles
Opis:
The paper presents results of bend tests at elevated temperatures of aluminium alloy EN AC-44200 (AlSi12) based composite materials reinforced with aluminium oxide particles. The examined materials were manufactured by squeeze casting. Preforms made of Al2O3 particles, with volumetric fraction 10, 20, 30 and 40 vol.% of particles joined with sodium silicate bridges were used as reinforcement. The preforms were characterised by open porosity ensuring proper infiltration with the EN AC-44200 (AlSi12) liquid alloy. The largest bending strength was found for the materials containing 40 vol.% of reinforcing ceramic particles, tested at ambient temperature. At increased test temperature, bending strength Rg of composites decreased in average by 30 to 50 MPa per 100°C of temperature increase. Temperature increase did not significantly affect cracking of the materials. Cracks propagated mainly along the interfaces particle/matrix, with no effect of the particles falling-out from fracture surfaces. Direction of cracking can be affected by a small number of agglomerations of particles or of non-reacted binder. In the composites, the particles strongly restrict plastic deformation of the alloy, which leads to creation of brittle fractures. At elevated temperatures, however mainly at 200 and 300°C, larger numbers of broken, fragmented particles was observed in the vicinity of cracks. Fragmentation of particles occurred mainly at tensioned side of the bended specimens, in the materials with smaller fraction of Al2O3 reinforcement, i.e. 10 and 20 vol.%.
Źródło:
Archives of Foundry Engineering; 2017, 17, 1; 103-108
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mieszane tlenki Mg-Cu-Fe pochodzenia hydrotalkitowego jako katalizatory procesu selektywnego utleniania amoniaku do azotu i pary wodnej (SCO)
Mixed metal oxides Mg-Cu-Fe obtained from hydrotalcites as catalysts for selective oxidation of ammonia to nitrogen and water vapor (SCO)
Autorzy:
Jabłoński, M.
Chmielarz, L.
Węgrzyn, A.
Powiązania:
https://bibliotekanauki.pl/articles/1219206.pdf
Data publikacji:
2012
Wydawca:
Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
Tematy:
materiały hydrotalkitowe
katalizatory tlenkowe
selektywne katalityczne utlenianie amoniaku
hydrotalkitowe materials
oxide catalysts
selective catalytic oxidation of ammonia
Opis:
Układy tlenkowe Mg-Cu-Fe pochodzenia hydrotalkitowego zostały przebadane jako katalizatory procesu selektywnego utleniania amoniaku do azotu i pary wodnej. Prekursory hydrotalkitowe zostały otrzymane metodą współstrącania, a następnie wysuszone i skalcynowane (600°C). Charakterystyka fizykochemiczna próbek obejmowała badania: strukturalne (XRD), teksturalne (BET), własności redoksowych (TPR). Eksperymenty katalityczne wykonano w układzie reaktora przepływowego. Analizę produktów reakcji przeprowadzono z zastosowaniem detektora QMS.
Mixed oxide Mg-Cu-Fe systems obtained form hydrotalcites were tested as catalysts for the selective catalytic oxidation (SCO) of ammonia to nitrogen and water vapor. Catalytic precursors were obtained by coprecipitation method. In the next step hydrotalkite-like materials were dried and calcined (600°C). Physico-chemical characterization of the samples included the following studies: structural analysis (XRD), textural measurements (BET) and redox experiments (TPR). Catalytic studies were performed in a fixed-bed flow reactor system. Analysis of reaction products was performed using QMS detector.
Źródło:
Chemik; 2012, 66, 7; 750-757
0009-2886
Pojawia się w:
Chemik
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selektywne katalityczne utlenianie (SCO) amoniaku do azotu i pary wodnej wobec mieszanych tlenków pochodzenia hydrotalkitowego – praca przeglądowa
Selective catalytic oxidation (SCO) of ammonia into nitrogen and water vapour over hydrotalcite originated mixed metal oxides – a short review
Autorzy:
Jabłońska, M.
Chmielarz, L.
Węgrzyn, A.
Powiązania:
https://bibliotekanauki.pl/articles/1216033.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
Tematy:
materiały hydrotalkitowe
katalizatory tlenkowe
selektywne katalityczne utlenianie amoniaku
hydrotalcite-like materials
oxide catalysts
selective catalytic oxidation of ammonia
Opis:
Selektywne katalityczne utlenianie amoniaku do azotu i pary wodnej jest obecnie uważane za jedną z najbardziej obiecujących metod usuwania amoniaku z gazów spalinowych i poprocesowych. W pracy omówiono technologię SCO, w tym stosowane w procesie katalizatory oraz mechanizmy przebiegu reakcji. Wykonano badania mieszanych tlenków pochodzenia hydrotalkitowego, w tym katalizatorów dwufunkcyjnych. Uzyskane wyniki jednoznacznie wskazują na duży potencjał materiałów hydrotalkitowych jako katalizatorów tego procesu. Zaproponowano dalsze kierunki badań w dziedzinie katalizatorów pochodzenia hydrotalkitowego dla procesu SCO.
Selective catalytic oxidation of ammonia into nitrogen and water vapour is currently regarded as one of the most promising technologies for abatement of ammonia emissions from waste gases. This paper gives an overview of SCO technology, including the catalyst development and possible mechanisms of SCO reaction. The use of mixed metal oxides obtained from synthetic hydrotalcite-like materials in the role of catalysts for the SCO reaction has been reviewed. Obtained results clearly show huge potential of tested materials as industrial catalysts. Finally, future research directions in the area of NH3 oxidation based on mixed oxide catalysts derived from hydrotalcite-like materials are proposed.
Źródło:
Chemik; 2013, 67, 8; 701-710
0009-2886
Pojawia się w:
Chemik
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Long-term chemical stability of BaCe0,85Y0,15O3-δ + Ce0,85Y0,15O2-δ composite samples at room temperature and at 873 K for use in dual PCFC-SOFC fuel cells
Długoczasowa stabilność próbek kompozytowych BaCe0,85Y0,15O3-δ + Ce0,85Y0,15O2-δ w temperaturze pokojowej oraz 873 K do zastosowania w ogniwach paliwowych typu PCF-SOFC
Autorzy:
Gawel, I.
Viviani, M
Przybylski, K.
Powiązania:
https://bibliotekanauki.pl/articles/356382.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
perovskites
solid oxide fuel cell electrolytes
chemical stability
composite materials
starzenie
metoda termicznej analizy różnicowej
stabilność chemiczna
materiały kompozytowe
Opis:
The goal of this work is to compare the long-term chemical stability of BaCe0,85Y0,15O3-δ and Ce0,85Y0,15O2-δ bulk composite samples to that of pure BaCe0,85Y0,15O3-δ after ageing for 600 hours in CO2 /H2 O atmosphere at room temperature and N2 /H2 O atmosphere at 873 K. Differential Thermal Analysis and Thermogravimetry were used to investigate the physicochemical processes that took place during the ageing of the afore-mentioned samples and the chemical composition of the gases released from the samples was analyzed by a Mass Spectrometer. The influence of the reactive atmospheres on phase and chemical composition, as well as the microstructure of the bulk samples, was determined from X-ray Diffraction results and Scanning Electron Microscopy observations combined with Energy Dispersion Spectroscopy analysis. From these studies it can be concluded that the composite materials are capable of maintaining stability in the studied conditions, however, pure BaCe0,85Y0,15O3-δis unstable in CO2 /H2 O atmosphere at room temperature.
Celem pracy jest porównanie długoczasowej stabilności chemicznej spieków kompozytowych BaCe0,85Y0,15O3-δ i Ce0,85Y0,15O2-δ z czystym BaCe0,85Y0,15O3-δ, które poddano starzeniu przez 600 godzin w atmosferze CO2 /H2 O w temperaturze pokojowej oraz w atmosferze N2 /H2 O w 873 K. Do badań procesów fizykochemicznych zachodzących podczas starzenia w/w próbek wykorzystano metodę termicznej analizy różnicowej oraz termograwimetrie, natomiast skład chemiczny gazów uwalnianych z próbek podczas ich ogrzewania analizowano spektrometrem masowym. Wpływ atmosfer reakcyjnych na skład fazowy i chemiczny oraz mikrostrukture spieków określono w oparciu o wyniki badań rentgenograficznych oraz obserwacji przy pomocy skaningowej mikroskopii elektronowej połączonej z dyspersją energii promieniowania rentgenowskiego. Z badań tych można wnioskować, że materiały kompozytowe wykazują stabilność w badanych warunkach, podczas gdy czysty BaCe0,85Y0,15O3-δ jest nietrwały w atmosferze CO2 /H2 O w temperaturze pokojowej.
Źródło:
Archives of Metallurgy and Materials; 2013, 58, 2; 393-397
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The influence of radiation modification on tribological properties of T5W, T7W plastics used in kinematics systems
Wpływ modyfikacji radiacyjnej na właściwości tribologiczne tworzyw T5W, T7W stosowanych w układach kinematycznych
Autorzy:
Bara, M.
Powiązania:
https://bibliotekanauki.pl/articles/191019.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
composite materials
radiation modification
oxide layers
friction coefficient
wear intensity
tworzywa kompozytowe
modyfikacja radiacyjna
warstwy tlenkowe
współczynnik tarcia
intensywność zużywania
Opis:
T5W and T7W plastics are a composite with a PTFE matrix and a prepared carbon powder as a dispersive phase. Due to the low friction coefficient value, these plastics are often used as a guide ring in the pneumatic and hydraulic piston–cylinder systems and the shock absorbers. This work attempts to increase wear resistant of plastics through the application of radiation modification. The plastics were associated with oxide layers obtained on the EN AW-5251 aluminium alloy via an electrochemical method route. Tribological tests were conducted on the T-17 tester in technically dry conditions.
Tworzywa T5W i T7W to kompozyty wytworzone na osnowie PTFE z fazą dyspersyjną w postaci proszku węgla preparowanego, używane do produkcji pierścieni prowadzących stosowanych w siłownikach pneumatycznych. Autor pracy podjął próbę zwiększenia odporności na zużycie tworzyw T5W, T7W stosowanych w układach tłok–cylinder, poprzez zastosowanie modyfikacji radiacyjnej. W pracy próbki z tworzywa zostały poddane kilkukrotnemu napromieniowaniu strumieniem elektronów, w dawce po 26 kGy. Tworzywa skojarzono z warstwami tlenkowymi stosowanymi na pokrycia wewnętrznych gładzi cylindrów niesmarowanych siłowników pneumatycznych. Warstwy tlenkowe wytworzono na podłożu stopu aluminium EN AW-5251 w procesie elektrochemicznego utleniania metodą stałoprądową. Badania tribologiczne przeprowadzono na testerze T-17. Tester przeznaczony jest do badań materiałów współpracujących ślizgowo w ruchu posuwisto-zwrotnym. Testy tribologiczne przeprowadzono w warunkach tarcia technicznie suchego, na drodze tarcia 50 km, ze wstępnym etapem 15 km docierania, stosując obciążenie 1 MPa oraz średnią prędkość ślizgania 0,2 m/s. Na podstawie danych otrzymanych w wyniku przeprowadzonego testu tribologicznego określono wpływ zastosowanej modyfikacji na intensywność zużywania badanych tworzyw oraz wartość współczynnika tarcia pary ślizgowej. Z analizy badań wynika, że przeprowadzenie modyfikacji radiacyjnej w dawce do 52 kGy dla tworzywa T5W oraz do 78 kGy dla tworzywa T7W wywołuje korzystne dla zastosowań tribologicznych zmiany w strukturze tych tworzyw. Nagłe obniżenie odporności zużyciowej tworzyw w wyniku zastosowania większych dawek promieniowania może być efektem degradacji struktury tworzywa.
Źródło:
Tribologia; 2013, 4; 9-15
0208-7774
Pojawia się w:
Tribologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 20

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