Temat: cermet - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Nanocomposites anode materials for Intermediate Temperature Solid Oxide Fuel Cell.
Nanokompozytowe materiały anodowe do ogniw paliwowych typu IT-SOFC.
Autorzy:: Zubik, Anna
Opis:: Stało-tlenkowe ogniwa paliwowe typu SOFC (Solid Oxide Fuel Cell) są obecnie przedmiotem intensywnych badań. Jest to spowodowane wysoką sprawnością konwersji energii chemicznej na elektryczną w tego typu ogniwach oraz niską emisją dwutlenku węgla. Niniejsza praca ma na celu otrzymanie i zbadanie nowej generacji materiałów anodowych do średniotemperaturowych ogniw paliwowych typu IT-SOFC dzięki czemu możliwym będzie obniżenie temperatury pracy ogniwa typu SOFC.W ramach projektu otrzymano kompozytowe materiały anodowe bazujące na tlenku ceru(IV) domieszkowanego miedzią i tlenku niklu(II) wykorzystując zmodyfikowaną metodę odwróconej mikroemulsji (w/o). Uzyskane prekursory poddano analizie termicznej w celu ustalenia optymalnych warunków kalcynacji. Morfologia powierzchni oraz dystrybucja porów w uzyskanych próbkach określono na podstawie metody niskotemperaturowej sorpcji azotu (N2- BET). Strukturę krystalograficzną i skład fazowy uzyskanych proszków wyznaczono na podstawie badań rentgenowskich (XRD). Uzyskane kompozyty poddano analizie przewodnictwa elektrycznego oraz badaniom metodą spektroskopii impedancyjnej. Wykazano, że w kompozycie typu core-shell istnieje zależność pomiędzy zawartością NiO, a właściwościami elektrycznymi materiału oraz jego aktywnością katalityczną w procesie utleniania metanolu. Wykazano wysoką stabilność kompozytów w zróżnicowanych atmosferach oraz zaproponowano optymalny skład kompozytu NiO-Ce0.8Cu0.2O2-y.
Solid oxide fuel cells (SOFCs) are currently the subject of intense investigation given their high chemical-to-electrical energy conversion efficiency and low emission of carbon dioxide. Present work is aimed to investigate of new generation of anode materials for IT-SOFC (Intermediate Temperature Solid Oxide Fuel Cell) what should result in lowering of operating temperature of SOFC. A simple modified reverse microemulsion method were applied to prepare composite powders for anode. The obtained precursor were investigated by thermal analysis methods in order to determine optimal calcination conditions. Surface morphology, specific surface area and pores distribution were evaluated on the basis of the N2-BET method. The structure of the obtained nanostructured powders was obtained from powder XRD measurements. The electrical conductivity measurements as well as impedance spectroscopy investigations were performed on the composites. It was shown that in the core-shell type composites there is a correlation between the content of NiO phase, electrical properties and catalytic activity in methanol oxidation process. High stability of the composites in different atmospheres was observed and the optimal composition of NiO-Ce0.8Cu0.2O2-y was proposed.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 2.

Tytuł:: Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets
Autorzy:: Matus, K.
Pawlyta, M.
Matula, G.
Gołombek, K.
Tematy:: carbide-steel cermet
HRTEM
STEM
tempering; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/356337.pdf Link otwiera się w nowym oknie
Opis:: The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Fe-Al based composite reinforced with ultra-fine Al2O3 oxides for high temperature applications
Autorzy:: Kopec, Mateusz
Jóźwiak, Stanisław
Kowalewski, Zbigniew
Tematy:: cermet composites
reaction synthesis
powder method
electron microscopy; Pokaż więcej
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Powiązania:: https://bibliotekanauki.pl/articles/2055052.pdf Link otwiera się w nowym oknie
Opis:: In this paper, an Fe-Al based composite reinforced with ultra-fine Al2O3 oxides was obtained through sintering of aluminium, iron and mullite ceramic powders using self-propagated high temperature synthesis (SHS). The powder mixture with a 50%wt. content of the ceramic reinforcement was cold pressed and subsequently subjected to the sintering process in vacuum at 1200◦C for 25 minutes under external loading of 25 kN. The complex microstructure of the Fe-Al matrix reinforced with ultra-fine Al2O3 oxides was found to be desired in high temperature applications since only 3% of the relative weight gain was observed after 100 hours of annealing at 900◦C.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Laser Cladding of WC/T-800 Cermet: Fabrication, Microstructure and Wear Properties
Autorzy:: Kim, Kyoung-Wook
Kim, Young-Kyun
Park, Sun-Hong
Lee, Kee-Ahn
Tematy:: CoMoCr alloy
WC
cermet
laser cladding
microstructure
wear properties; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2049250.pdf Link otwiera się w nowym oknie
Opis:: This study fabricated a WC/T-800 cermet coating layer with Co-Mo-Cr (T-800) powder and WC powder using laser cladding, and analyzed its microstructure, hardness and wear properties. For comparison, casted bulk T-800 was used. Laser cladded WC/T-800 cermet coating layer showed circular WC phases in the Co matrix, and dendritic laves phases. The average laves phase size in the cermet coating layer and bulk T-800 measured as 7.9 µm and 60.6 µm, respectively, indicating that the cermet coating layer had a relatively finer laves phase. Upon conducting a wear test, the cermet coating layer added with WC showed better wear resistance. In the case of laser cladded WC/T-800 cermet coating layer, abrasion wear was observed; on the contrary, the bulk T-800 showed pulled out laves phases. Based on the above findings, the WC/T-800 cermet coating layer using laser cladding and the relationship between its microstructure and wear behavior were discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: High-Velocity Impact of 2-Phase WC/Co Composite Plate - Beginning of the Process
Autorzy:: Postek, E.
Sadowski, T.
Tematy:: 2-phase composites
cermet
Johnson-Cook plasticity
impact
numerical modelling; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/351505.pdf Link otwiera się w nowym oknie
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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Microstructure and Properties of TiC/Ti Coatings Deposited by the Supersonic Cold Gas Spray Technique
Autorzy:: Kusiński, J.
Kac, S.
Kowalski, K.
Dosta, S.
Georgiou, E. P.
Garcia-Forgas, J.
Matteazzi, P.
Tematy:: cold gas spraying
Ti
TiC
CerMet coating
SEM
TEM
wear resistance; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/356608.pdf Link otwiera się w nowym oknie
Opis:: Nanostructured, biocompatible, TiC/Ti Supersonic Cold Gas Sprayed coatings were deposited onto a Ti6Al4V alloy and their microstructure, wear resistance and hardness were investigated. The starting nanostructured powder, containing a varied mixture of Ti and TiC particles, was produced by high energy ball milling. Scanning and transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction were used for structural and chemical analyses of powder particles and coatings. Coatings, 250-350 μm thick, preserving the nanostructure and chemical powder composition, with low porosity and relatively high hardness (~850 HV), were obtained. These nanostructured TiC/Ti coatings exhibited better tribological properties than commonly used biomedical benchmark materials, due to an appropriate balance of hard and soft nano-phases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Reprocessability of molybdenum and magnesia based inert matrix fuels
Autorzy:: Ebert, E. L.
Bukaemskiy, A.
Sadowski, F.
Lange, S
Wilden, A.
Modolo, G.
Tematy:: CERCER
CERMET
dissolution
inert matrix fuels (IMF)
liquid-liquid extraction
minor actinides
reprocessing; Pokaż więcej
Wydawca:: Instytut Chemii i Techniki Jądrowej
Powiązania:: https://bibliotekanauki.pl/articles/148138.pdf Link otwiera się w nowym oknie
Opis:: This work focuses on the reprocessability of metallic 92Mo and ceramic MgO, which is under investigation for (Pu,MA)-oxide (MA = minor actinide) fuel within a metallic 92Mo matrix (CERMET) and a ceramic MgO matrix (CERCER). Magnesium oxide and molybdenum reference samples have been fabricated by powder metallurgy. The dissolution of the matrices was studied as a function of HNO3 concentration (1–7 mol/L) and temperature (25–90°C). The rate of dissolution of magnesium oxide and metallic molybdenum increased with temperature. While the MgO rate was independent of the acid concentration (1–7 mol/L), the rate of dissolution of Mo increased with acid concentration. However, the dissolution of Mo at high temperatures and nitric acid concentrations was accompanied by precipitation of MoO3. The extraction of uranium, americium, and europium in the presence of macro amounts of Mo and Mg was studied by three different extraction agents: tri-n-butylphosphate (TBP), N,N'-dimethyl-N,N'-dioctylhexylethoxymalonamide (DMDOHEMA), and N,N,N’,N’- -tetraoctyldiglycolamide (TODGA). With TBP no extraction of Mo and Mg occurred. Both matrix materials are partly extracted by DMDOHEMA. Magnesium is not extracted by TODGA (D < 0.1), but a weak extraction of Mo is observed at low Mo concentration.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Comparative Analysis of Mechanical Properties of WC-based Cermet Coatings Sprayed by HVOF onto AZ31 Magnesium Alloy Substrates
Autorzy:: Jonda, Ewa
Łatka, Leszek
Tematy:: mechanical properties
microstructure
fracture toughness
indentation test
cermet coating
HVOF spraying
magnesium alloy AZ31; Pokaż więcej
Wydawca:: Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Powiązania:: https://bibliotekanauki.pl/articles/2024046.pdf Link otwiera się w nowym oknie
Opis:: Magnesium alloys are very interesting engineering materials due to their very high strength to density ratio (the best among metallic alloys). However, because of low hardness as well as low resistance against erosion, abrasion and corrosion, their applications in the industry is very limited. In order to improve mechanical performances, deposition of hardening coating by thermal spraying was proposed. In this work, the WC-based coatings with different binder (Co or Ni) and co-hardening additives (Cr or Cr3C2) manufactured by high velocity oxy-fuel (HVOF) were studied. These coatings were deposited onto AZ31 magnesium alloy. The crucial problem is obtaining good-adhered coating without damage the substrate, because of relatively low temperature resistance of magnesium alloys (about 300 °C). To solve this problem, HVOF method, which is low temperature and high velocity, was proposed. Also an important role plays process parameters (e.g. spray distance, fuel medium, type of nozzle). The goal of the study was to compare three types of cermet coatings manufactured from commercially available powders (WC-Co, WC-Co-Cr and WC-Cr3C2-Ni) in terms of their microstructure features, microhardness, instrumented indentation and fracture toughness. Results revealed that selected process parameters made it possible to obtain well-adhered coating with good fulfillment of the surface unevenness of the AZ31 substrate. The most noticeable effect was influence of cobalt matrix on higher hardness (1.4 – 1.6 GPa) and Young modulus (330 – 340 GPa) of deposited coatings in compare to the nickel matrix ones (1.2 GPa and 305 GPa, respectively). The same trend was observed in case of fracture toughness, c.a. 6.5 MPa·m1/2 for Co-matrix and 4.9 MPa·m1/2 for Ni-matrix
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Properties of TiC-Mo2C-WC-Ni Cermets by a High-Energy Ball Milling/Spark Plasma Sintering
Autorzy:: Lee, Jeong-Han
Park, Jae-Cheol
Park, Hyun-Kuk
Tematy:: TiC-based cermet
core-rim structure
high-energy ball-milling
spark plasma sintering
microstructure; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/2203731.pdf Link otwiera się w nowym oknie
Opis:: A TiC-Mo2C-WC-Ni alloy cermet was fabricated by high-energy ball milling (HEBM) and consolidation through spark plasma sintering. The TiC-based powders were synthesized with different milling times (6, 12, 24, and 48 h) and subsequently consolidated by rapid sintering at 1300°C and a load of 60 MPa. An increase in the HEBM time led to improved sinterability as there was a sufficient driving force between the particles during densification. Core-rim structures such as (Ti, W)C and (Ti, Mo)C (rim) were formed by Ostwald ripening while inhibiting the coarsening of the TiC (core) grains. The TiC grains became refined (2.57 to 0.47 µm), with evenly distributed rims. This led to improved fracture toughness (11.1 to 14.8 MPa·m1/2) owing to crack deflection, and the crack propagation resistance was enhanced by mitigating intergranular fractures around the TiC core.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Natryskiwane zimnym gazem powłoki odporne na ścieranie
Wear resistant coatings deposited by cold gas spraying
Autorzy:: Kusiński, J.
Kąc, S.
Kowalski, K.
Matteazzi, P.
Dosta, S.
Georgiou, E.
Tematy:: mechaniczna synteza
powłoki metal/ceramika
mikrostruktura
twardość
testy tribologiczne
high energy ball milling
cermet coatings
microstructure
hardness
tribological tests; Pokaż więcej
Wydawca:: Politechnika Rzeszowska im. Ignacego Łukasiewicza. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/195791.pdf Link otwiera się w nowym oknie
Opis:: Naukowym i technologicznym celem badań było wytworzenie nanostrukturalnych powłok FeCuAl-Al2O3, WC-CoAl, Ni-Sn, TiC/Ti o grubości od 45 do 500 μm. Nanoproszki charakteryzujące się strukturą krystaliczną i równomiernym rozmieszczeniem składników otrzymywano, stosując wysokoenergetyczną syntezę mechaniczną. Proszek o strukturze nanokrystalicznej był nanoszony na podłoże bez istotnych zmian jego struktury i właściwości, z wykorzystaniem nowej technologii (natryskiwania zimnym gazem – CGS), pozwalającej uzyskiwać powłoki o dużej gęstości. Mikrostrukturę oraz skład chemiczny nanoproszków i nanoszonych powłok analizowano, wykorzystując mikroskopię świetlną, TEM, STEM, SEM/EDS, XPS oraz XRD. Ponadto mierzono współczynnik tarcia oraz odporność na ścieranie powłok. Przeprowadzone badania wykazały, że mikrostruktura powłok odpowiada strukturze nanoszonych proszków. Dzięki nanostrukturalnej budowie powłok, właściwej proporcji faz twardych i miękkich, natryskiwane zimnym gazem powłoki wykazują lepsze właściwości trybologiczne w porównaniu z materiałami standardowo stosowanymi w przemyśle i bioinżynierii.
The basic scientific and technological aim of the research was the generation of nano-structured FeCuAl-Al2O3, WC-CoAl, Ni-Sn, TiC/Ti coatings having thicknesses of about 100-500 μm. High energy ball milling synthesis allowed the production of powders characterized by fine and homogeneous chemical distribution of elements, and an "ultrafine" (nanometer scale) crystalline structure. A new powerful deposition technology (Cold Gas Spray – CGS) was used to transfer the nanophased powder onto the substrate in the form of a dense coating with very little or no change of crystal structure and properties. The microstructure and composition of all prepared nano-powders and deposited coatings were investigated using light microscopy, TEM, STEM, SEM/EDS, XPS and XRD techniques. Hardness, and measurement of the coefficient of friction and wear resistance were carried out on the deposited coatings. It was found that the microstructure of the powder is maintained in the deposited coating. The nano phased structure, with an appropriate balance of hard and soft phases, allows the CGS coatings to exhibit better tribological properties than that of the examined benchmark materials.
Dostawca treści:: Biblioteka Nauki

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