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Tytuł:
Ocena korozji stali podczas geologicznej sekwestracji dwutlenku węgla
Assessment of steel corrosion during geological carbon sequestration
Autorzy:
Masłowski, Mateusz
Powiązania:
https://bibliotekanauki.pl/articles/31343912.pdf
Data publikacji:
2023
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
korozja
ocena
stal
dwutlenek węgla
faza nadkrytyczna CO2
sekwestracja dwutlenku węgla
corrosion
steel
assessment
carbon dioxide
CO2 supercritical phase
carbon dioxide sequestration
Opis:
W artykule przedstawiono tematykę związaną z korozją stali podczas geologicznej sekwestracji dwutlenku węgla. Ma to związek z tworzeniem się środowiska korozyjnego w obecności wody w środowisku CO2. Następuje wówczas pogorszenie się właściwości stali w wyniku jej reakcji z otaczającym środowiskiem i przechodzeniem wolnego metalu w związki, co wpływa w znacznym stopniu na bezpieczeństwo pracy urządzeń oraz stan rur stalowych. Opracowaną procedurę symulacji zjawiska korozji, metodykę badań, analiz i oceny korozji zweryfikowano testami laboratoryjnymi. Do testów zastosowano próbki stali L-80 (13Cr) wycięte z rury eksploatacyjnej. Natomiast środowisko korozyjne stanowił wilgotny czysty dwutlenek węgla o zawartości wody destylowanej wynoszącej 5000 ppm. Testy korozji przeprowadzono dla dwóch temperatur (40°C i 80°C) i dwóch ciśnień (8 MPa i 20 MPa), umożliwiających uzyskanie CO2 w fazie nadkrytycznej. Na podstawie wykonanych fotografii powierzchni stali nie stwierdzono widocznej korozji. Po testach korozji powierzchnie kuponów miały nadal charakter metaliczny, błyszczący. Wyznaczone na podstawie ubytku masy wartości szybkości korozji także nie wykazały procesu korozji stali w środowisku zawilgoconego CO2 dla zadanych warunków T i P. Dodatkowo wykonane obrazowanie i analiza powierzchni stali pod mikroskopem optycznym pozwoliły na zaobserwowanie początku tworzenia się korozji ogólnej (równomiernej) i wżerowej (miejscowej). Określono wielkości charakteryzujące wżery (średnią i maksymalną głębokość). Głębokość powstałych wżerów była rzędu od 0,00569 mm do 0,017 mm. Największą głębokość uzyskano w teście 4 (T = 80°C i P = 20 MPa). Na tej podstawie wyznaczono wartości szybkości korozji oraz wykonano dodatkową teoretyczną analizę głębokości korozji po 1 roku, 10, 50 i 100 latach. Pozwoliła ona stwierdzić, że niebezpieczna głębokość wżerów dla stali L-80 (13Cr) pojawi się po okresie 10 lat.
This paper discusses steel corrosion during geological sequestration of carbon dioxide. It is caused by formation of a corrosive environment in the presence of water in the CO2 environment. A deterioration of steel properties is a result of its reaction with the surrounding environment and the transition of free metal into compounds. This has a significant impact on the operational safety of equipment and steel pipes. The developed procedure for simulating the phenomenon of corrosion, the methodology of research, analysis and corrosion assessment were verified by laboratory tests. L80 (13Cr) steel samples cut from a service pipe were used for the tests. The corrosive environment was humid pure carbon dioxide with a content of distilled water of 5000 ppm. Corrosion tests were carried out for two temperatures (40 and 80°C) and two pressures (8 and 20 MPa), enabling CO2 to be obtained in the supercritical phase. No visible corrosion was found on the basis of the photographs of the steel surface. After the corrosion tests, the surfaces of the coupons were still metallic and shiny. The corrosion rate values determined on the basis of mass loss also did not show the corrosion process of steel in an environment moistened with CO2 for the given conditions T and P. Additional imaging and analysis of the corrosion pit surface under the optical microscope made it possible to observe the beginning of the formation of general (uniform) and pitting (local) corrosion. The values characterizing the pits (average and maximum depth) were determined. The depth of the resulting pits ranged from 0.00569 mm to 0.017 mm. The greatest depth was obtained in test 4 (T = 80°C and P = 20 MPa). On their basis, it was suggested to determine the value of the corrosion rate and perform an additional theoretical analysis of the corrosion depth after 1, 10, 50 and 100 years. This would enable the emergence of dangerous depth of pits for steel L-80 (13Cr) after a period of 10 years to be observed.
Źródło:
Nafta-Gaz; 2023, 79, 5; 326-337
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quantum-inspired evolutionary optimization of SLMoS2 two-phase structures
Autorzy:
Kuś, Wacław
Mrozek, Adam
Powiązania:
https://bibliotekanauki.pl/articles/29520072.pdf
Data publikacji:
2022
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
quantum-inspired evolutionary algorithm
optimization
nanostructure
two-phase SLMoS2
molecular dynamics
molecular statics
atomic potential
ReaxFF
material properties
Opis:
The paper focuses on applying a Quantum Inspired Evolutionary Algorithm to achieve the optimization of 2D material containing two phases, 2H and 1T, of Molybdenum Disulphide (MoS2). The goal of the optimization is to obtain a nanostructure with tailored mechanical properties. The design variables describe the shape of inclusion made from phase 1T in the 2H unit cell. The modification of the size of the inclusions leads to changes in the mechanical properties. The problem is solved with the use of computed mechanical properties on the basis of the Molecular Statics approach with ReaxFF potentials.
Źródło:
Computer Methods in Materials Science; 2022, 22, 2; 67-78
2720-4081
2720-3948
Pojawia się w:
Computer Methods in Materials Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Ca Precipitation in Al-Mg Alloys Containing a Trace of Ca During Homogenization
Autorzy:
Ha, Seong-Ho
Shin, Young-Chul
Kim, Bong-Hwan
Yoon, Young-Ok
Lim, Hyun-Kyu
Lim, Sung-Hwan
Kim, Shae K.
Powiązania:
https://bibliotekanauki.pl/articles/2049165.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Mg system
precipitation
Mg+Al2Ca mater alloy
transmission electron microscope
phase diagram
Opis:
In this study, precipitation of Ca in Al-Mg alloys containing a trace of Ca during homogenization was investigated using a transmission electron microscope (TEM) and calculated phase diagrams. TEM result indicated that the Ca-based particles found in the examined sample are Ca7Mg7.5Si14. From the calculation of Scheil-Gulliver cooling, it was found that the Ca was formed as Al4Ca and C36 laves phases with Mg2Si and Al13Fe4 from other impurities phase during solidification. No Ca-Mg-Si ternary phase existed at the homogenization temperature in the calculated phase diagram. From the phase diagram of Al-Al4Ca-Mg2Si three-phase isothermal at 490°C, it was shown that Ca7Mg6Si14 phase co-exists with Al, Mg2Si and Al4Ca in the largest region and with only Al and Mg2Si in Al4Ca-poor regions. It was thought that the Ca7Mg6Si14 ternary phase was formed by the interaction between Mg2Si and Al4Ca considering that the segregation can occur throughout the entire microstructures.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 959-962
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure Formation of Al-5 mass%Mg Alloy Melts by Interaction with Silica
Autorzy:
Kim, Sun-Ki
Ha, Seong-Ho
Kim, Bong-Hwan
Yoon, Young-Ok
Lim, Hyun-Kyu
Kim, Shae K.
Kim, Yong-Jig
Powiązania:
https://bibliotekanauki.pl/articles/2049152.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Mg system
silica
reduction
Mg2Si
phase diagram
Opis:
Dissolution of Si in Al-5 mass%Mg alloy melt by the reduction of SiO2 and its effect on microstructure formation of the alloy after solidification were investigated. Al-5 mass%Mg alloy without silica powder had approximately 0.05 mass%Si as an impurity. No significant difference in Si content was observed after the reaction with silica for 10 min, while the Si content increased up to about 0.12 mass% after 30 min. From the microstructure analysis and calculation of Scheil-Gulliver cooling, it was considered that as-cast microstructures of Al-5 mass%Mg-1 mass% SiO2 alloys had the distribution of eutectic phase particles, which are comprised of β-Al3Mg2 and Mg2Si phases. Based on the phase diagrams, only limited amount of Mg can be selectively removed by silica depending on the ratio of Si and Mg. Addition of silica of more than approximately 1.5 mass% in Al-5 mass%Mg alloy led to the formation of spinel and removal of both mg and Al from the melt.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 947-950
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-Velocity Impact of 2-Phase WC/Co Composite Plate - Beginning of the Process
Autorzy:
Postek, E.
Sadowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/351505.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
2-phase composites
cermet
Johnson-Cook plasticity
impact
numerical modelling
Opis:
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 Al2 O3 /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. Al2 O3 /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.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 1; 265-274
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The impact of semester-abroad experiences on post-sojourn L2 motivation
Autorzy:
Du, Xujia
Powiązania:
https://bibliotekanauki.pl/articles/780569.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
L2 motivation
L2 learning experience in study abroad
post-sojourn phase
critical reflection
Opis:
Numerous studies have examined sojourners’ L2 motivation during their stay abroad. Much remains unknown about the impact of study abroad (SA) experiences on their L2 motivation after they return to the home environment. This study tracked the English learning motivation of three Chinese university students from immediately after their semester-long exchange program in an English-speaking country until six months after the sojourn. The participants were requested to complete a questionnaire and took part in an interview immediately following their re-entry and another interview six months later. The participants’ post-sojourn English learning motivation was influenced by their L2 selves and the context they were situated in. The motivational capacity of SA experiences was manifested in its profound impact on the participants’ ideal L2 self-images. Satisfactory SA experiences contributed to an ideal L2 self with higher L2 proficiency and international posture, whereas unsatisfactory experiences led to a lessening role of L2 in the participants’ future work and life. The findings also reveal that the participants’ understandings of both their positive and negative SA experiences became fossilized after the sojourn. Some practical implications were discussed for higher education institutions to optimize the post-sojourn motivational impact of SA programs.
Źródło:
Studies in Second Language Learning and Teaching; 2019, 9, 1; 117-155
2083-5205
2084-1965
Pojawia się w:
Studies in Second Language Learning and Teaching
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The phase separation phenomenon in the Na2O–B2O3–SiO2–Fe2O3 glass-forming system and its application for producing porous glasses
Autorzy:
Konon, Marina
Antropova, Tatyana
Polyakova, Irina
Anfimova, Irina
Dikaya, Lidiya
Semenova, Ekaterina
Kurilenko, Ludmila
Powiązania:
https://bibliotekanauki.pl/articles/173829.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
Na2O–B2O3–SiO2–Fe2O3 glass-forming system
phase separation
crystallization
phase separation diagram
chemical durability
magnetite
leaching
porous glass
Opis:
Glasses in the Na2O–B2O3–SiO2–Fe2O3 system with a constant SiO2 content 70 mol% were synthesized using conventional melting in platinum crucibles in SiC-furnace in air. After synthesis and annealing, glasses were heat treated at 550°C for 96–144 hrs to promote phase separation. A tentative region of phase separation for this temperature was outlined. X-ray powder diffractometry results showed three iron-containing phases (Fe3O4, FeSiO3 and β-Fe2O3) forming in the investigated glasses with magnetite being the main phase as it is observed in most of the glasses. Chemical durability studies showed that compositions of phase-separated glasses suitable for synthesis of porous glasses, both iron-free and iron-containing lie in between 4 and 8 mol% of Na2O. Bulk samples of porous glasses were obtained within the chosen region having the following parameters: specific surface area 40–185 m2/g, porosity 30%–45%, pore diameter 3–14 nm. The parameters of porous structure of iron-containing porous glasses are of the same order of magnitude as the porous glass used for the multiferroic nanocomposite synthesis.
Źródło:
Optica Applicata; 2019, 49, 3; 437-444
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Mo-Si-B Intermetallic Compound Powders Under Different Heat Treatment Conditions
Autorzy:
Park, J. H.
Lee, S.
Kim, D.
Kim, Y.
Yang, S. H.
Lee, S. H.
Powiązania:
https://bibliotekanauki.pl/articles/353369.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Mo-Si-B alloys
intermetallic compounds
reitveld refinement
T2 phase
A15 phase
Opis:
In this research, we investigated the effects of reduction atmospheres on the creation of the Mo-Si-B intermetallic compounds (IMC) during the heat treatments. For outstanding anti-oxidation and elevated mechanical strength at the ultrahigh temperature, we fabricated the uniformly dispersed IMC powders such as Mo5SiB2 (T2) and Mo3Si (A15) phases using the two steps of chemical reactions. Especially, in the second procedure, we studied the influence of the atmospheres (e.g. vacuum, argon, and hydrogen) on the synthesis of IMCs during the reduction. Furthermore, the newly produced IMCs were observed by SEM, XRD, and EDS to identify the phase of the compounds. We also calculated an amount of IMCs in the reduced powders depending on the atmosphere using the Reitveld refinement method. Consequently, it is found that hydrogen atmosphere was suitable for fabrication of IMC without other IMC phases.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1509-1512
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Określanie profili metabolitów lotnych produkowanych przez izolaty Trametes versicolor wykazujące antagonistyczne działanie w stosunku do Armillaria spp.
Determination of profiles of volatile metabolites produced by Trametes versicolor isolates antagonistic towards Armillaria spp.
Autorzy:
Szwajkowska-Michałek, L.
Buśko, M.
Łakomy, P.
Perkowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/986657.pdf
Data publikacji:
2018
Wydawca:
Polskie Towarzystwo Leśne
Tematy:
lesnictwo
fitopatologia lesna
opienkowa zgnilizna korzeni
Armillaria
rozwoj grzybni
ograniczenie rozwoju
Trametes versicolor
izolaty grzybowe
Trametes versicolor TR31
Trametes versicolor TR55
metabolity grzybow
metabolity lotne
lotne zwiazki organiczne
inhibited growth of armillaria
volatile metabolites of trametes versicolor
solid phase microextraction
(spme)
aldehydes
alcohols
2−methylbutanal
Opis:
Armillaria root disease is one of the most important diseases causing losses in forestry, horticulture, pomiculture and agriculture. Fungi from Armillaria spp. infest roots and stem base in trees and shrubs, causing white wood rot. In Poland the most common species include Armillaria ostoyae (Romagn.) Herink, found both in coniferous and deciduous stands, and A. gallica Marxm. et Romagn. found in deciduous stands. Identification of antagonistic interactions between microorganisms in the soil medium enables to use their activity to protect plants against pathogens. Analyses were conducted on two Trametes versicolor isolates TR31 and TR55, collected from oak stumps, and 5 fungal species from the genus Armillaria: A. borealis Marxm. et Korhonen, A. cepistipes Velen., A. gallica, A. mellea (Vahl) P. Kumm. and A. ostoyae. Profiles of volatile compounds produced by T. versicolor isolates TR31 and TR55 determined in this study varied in their effect on growth of pathogens Armillaria borealis, A. cepistipes, A. gallica, A. mellea and A. ostoyae. TR31 more effectively than isolate TR55 inhibited growth of fungi from the genus Armillaria. Profiles of volatile compounds biosynthesised in the examined fungal cultures were assessed by headspace microextraction in a gas chromatograph coupled with a mass spectrometer. We detected 179 compounds in the analysed fungal cultures. They belonged to the following groups of chemical compounds: amines, alcohols, terpenes, aldehydes, ketones, hydrocarbons, heterocyclic compounds, esters and aromatic compounds (tab. 2). The most numerous group among the isolated volatile compounds comprised hydrocarbons, alcohols and esters at 32.4%, 16.2% and 14.5%, respectively. The highest concentrations reported in RU (i.e. the peak area of a given substances in relation to the peak area of the internal standard, i.e. tridecane) were recorded for aldehydes, alcohols and hydrocarbons. Among all the identified volatile compounds the highest concentration was observed for 2−methylbutanal. However, it was characteristic only of isolate TR31, which exhibited a greater capacity to inhibit growth of Armillaria spp. in comparison to isolate TR55 (fig.).
Źródło:
Sylwan; 2018, 162, 06; 499-508
0039-7660
Pojawia się w:
Sylwan
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface functionalization of poly(L-lactide-co-glycolide) membranes with amphiphilic poly(2-oxazoline) for guided tissue regeneration and treatment of bone tissue defects
Autorzy:
Tryba, A. M.
Krok-Borkowicz, M.
Paluszkiewicz, C.
Pamuła, E.
Powiązania:
https://bibliotekanauki.pl/articles/283890.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
poly (L-lactide-co-glycolide)
poly (ethylene glycol)
poly (2-oxazolines)
phase separation
Fourier transform infrared spectroscopy (FTIR)
osteoblast-like cells
guided tissue regeneration (GTR)
bone tissue engineering
Opis:
The main challenge of this research was to functionalize the surface of poly(L-lactide-co-glycolide) (PLGA) membranes with amphiphilic poly(2-oxazoline) (POx) in order to change PLGA chemical state and properties. Poly(2-oxazolines) are very powerful polymers, which thanks to active pendant groups can be easily functionalized with biologically active molecules or peptides. The membranes were prepared by dissolving PLGA, POx, and poly(ethylene glycol) (PEG, 1000 Da) in methylene chloride (DCM), followed by PEG leaching. POx molecules were preferentially adsorbed at the interface PLGA-POx-PEG thanks to affinity to both hydrophilic (PEG) and hydrophobic (PLGA) chains. The properties of the membranes were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and wettability tests. Cytocompatibility of the materials in contact with osteoblast-like MG-63 cells was studied by evaluation of cell viability (Alamar-Blue test), live/dead and phalloidin/DAPI staining. The results show that the presence of POx influenced topography of the PLGA membranes, but did not have an impact on their wettability. All membranes were fo-und cytocompatible with model osteoblasts. Presence of POx resulted in better cell adhesion as shown by microscopic studies after fluorescence staining for nuclei and cytoskeleton actin filaments. In summary, one-step phase separation process between PLGA, PEG, and POx, dissolved in DCM followed by drying and PEG leaching resulted in cytocompatible PLGA membranes with immobilised POx, which might be considered for guided tissue regeneration technique in periodontology and in bone tissue engineering.
Źródło:
Engineering of Biomaterials; 2018, 21, 147; 16-20
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Plastic Deformation During Extrusion Process on Heat Resistance Alloys Fe40Al
Autorzy:
Pasek, D.
Cebulski, J.
Powiązania:
https://bibliotekanauki.pl/articles/352208.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
corrosion resistance
plastic deformation
alloys intermetallic phase matrix FeAl
Al2O3
extrusion
Opis:
The article presents the results of studies on the effects wrought on the corrosion resistance of the alloy matrix phase inter-metallic FeAl. Researches were carried out on the Fe40Al5Cr0.2TiB alloy and involved the oxidation of the samples after the crystallization after plastic deformation made by extrusion. The tests were performed in an oven in air at 1100°C for 100, 300 and 500 h. Determined to change the mass of the samples after corrosion research setting kinetics of corrosion processes, as well as an analysis of the microstructure of the alloy after the crystallization and after forming. The structure was examined using light microscopy and scanning electron microscopy and X-ray microanalysis with EDS chemical composition of the corrosion products. The test results revealed that plastic deformation during extrusion of intermetallic alloy led to structural changes, the effect of which was to improve the heat resistance at a temperature of 1100°C.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 4; 2281-2286
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction
Autorzy:
Choi, S. H.
Ali, B.
Choi, K. S.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, T. H.
Kim, T. S.
Park, K. T.
Powiązania:
https://bibliotekanauki.pl/articles/355326.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
solid state reaction
kinetic analysis
quantitative phase analysis
TiNb2O7 synthesis
Opis:
Although TiNb2O7 is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb2O7 compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb2O7 phase, the starting materials, TiO2 and Nb2O5 were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1051-1056
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Barium oxide as a modifier to stabilize the γ-Al2O3 structure
Autorzy:
Pakdeh, S. G.
Rasoolzadeh, M.
Moghadam, A. S.
Powiązania:
https://bibliotekanauki.pl/articles/778807.pdf
Data publikacji:
2016
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
γ-Al2O3
thermal stability
phase transition
barium oxide
pentacoordinated Al3+ ions
Opis:
This research concentrated on the structural stability of γ-alumina (γ-Al2O3 ) was investigated by a combination of differential thermal analysis, X-ray diffractometry and surface-area measurements. The γ –to– θ and then α phase transitions were observed as an exothermic peak at 1000°C–1400°C in the DTA curves. The role of barium oxide as a modifier to stabilize γ-Al2O3  structure has been investigated. XRD measurements show that after calcination at 1000°C for 2 h, a significant fraction of the pure γ-Al2O3  (BaO-free) transformed to θ-Al2O3  while that the transition phase in alumina samples modified by BaO have been reduced significantly. Barium oxide, eliminate pentacoordinated aluminum ions through coordinative saturation and alter these ions into octahedral cations and effectively suppressed the γ –to– α phase transition in Al2O3 , which concluded as improving the thermal stability and porous properties of the experimental samples.
Źródło:
Polish Journal of Chemical Technology; 2016, 18, 4; 1-4
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Cooling Rate after Homogenization on the Microstructure and Properties of 2017a Alloy Billets for Extrusion with Solution Heat Treatment on the Press
Autorzy:
Woźnicki, A.
Leśniak, D.
Włoch, G.
Pałka, P.
Leszczyńska-Madej, B.
Wojtyna, A.
Powiązania:
https://bibliotekanauki.pl/articles/355500.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
2017A alloy
cooling rate after homogenization
θ (Al2Cu) phase particles precipitation
Opis:
The influence of cooling rate after homogenization on the 2017A alloy microstructure was analysed. The capability of the θ (Al2Cu) particles, precipitated during various homogenization coolings, for rapid dissolution was estimated. For this purpose, the DSC test was used to determine the effect of the cooling rate after homogenization on the course of melting during a rapid heating. Moreover, the samples after solution heat treatment (with short time annealing) and ageing, were subjected to the microstructure investigations and the microhardness of grains interiors measurements. It was found that cooling after homogenization at 160 °C/h is sufficient for precipitation of fine θ phase particles, which dissolve during the subsequent rapid heating. The cooling at 40 °C/h, causes the precipitation of θ phase in the form of large particles, incapable of further fast dissolution.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 3; 1663-1670
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tunnel support design by comparison of empirical and finite element analysis of the Nahakki Tunnel in Mohmand Agency, Pakistan
Autorzy:
Riaz, A.
Jamil, S. M.
Asif, M.
Akhtar, K.
Powiązania:
https://bibliotekanauki.pl/articles/178620.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
rock mass strength parameters
rock mass classification
FEM analysis
Phase2
tunnel support design
Opis:
The paper analyses the geological conditions of study area, rock mass strength parameters with suitable support structure propositions for the under construction Nahakki tunnel in Mohmand Agency. Geology of study area varies from mica schist to graphitic marble/phyllite to schist. The tunnel ground is classified and divided by the empisical classification systems like Rock mass rating (RMR), Q system (Q), and Geological strength index (GSI). Tunnel support measures are selected based on RMR and Q classification systems. Computer based finite element analysis (FEM) has given yet another dimension to design approach. FEM software Phase2 version 7.017 is used to calculate and compare deformations and stress concentrations around the tunnel, analyze interaction of support systems with excavated rock masses and verify and check the validity of empirically determined excavation and support systems.
Źródło:
Studia Geotechnica et Mechanica; 2016, 38, 1; 75-84
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł

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