Wyniki wyszukiwania - Biblioteka Nauki

1

Aktualizowanie treści i zasobu polskich norm w związku z wdrożeniem norm europejskich

100%

Siemińska M.

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2005

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tom R. 53, nr 4

16-17

2

Electrical Properties of BaCeO₃-Based Electrolytes for use in Dual Protonic Ceramic-Solid Oxide Fuel Cells

80%

Gawel R. , Przybylski K.

Acta Physica Polonica A

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2017

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tom 131

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nr 5

1361-1366

EN

Bulk samples consisting of BaCe_{0.85}Y_{0.15}O_{3-δ} (BCY15) and Ce_{0.85}Y_{0.15}O_{2-δ} (YDC15) compounds, mixed together in different ratios, were studied as potential electrolytes in dual protonic ceramic-solid oxide fuel cells and compared with non-composite BCY15 and YDC15. The microstructures of the sintered materials indicate that BCY15 exhibits the largest grains, whereas composites have greater visible porosity than the non-composite samples. From X-ray diffraction studies it follows that BCY15 and YDC15 consist mainly of one phase, whereas the composites are two-phase materials. Electrochemical impedance spectroscopy studies at different temperatures show that the composite materials are capable of conduction the order of 10¯³ S/cm at temperatures above 500°C in a hydrogen-containing atmosphere. Furthermore, activation energy values of the conductivity determined for the composites in air atmosphere are between those obtained for BCY15 (E_{a}=0.590±0.017 eV) and YDC15 (E_{a}=1.132±0.008 eV). From this it follows that both phases of the composites influence the electrical conductivity of the materials. In conclusion, BCY15 and the BCY15-YDC15 composites show promise for future use as electrolytes in dual protonic ceramic-solid oxide fuel cells.

3

Złoty jubileusz krotoszyńskiej szkoły ceramików

80%

Kryszkiewicz A. , Kaszkowiak J.

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1998

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tom R. 40, nr 5

17-18

4

Structural and dielectric properties of La substituted polycrystalline Ca(Ti0.5Fe0.5)O3

80%

Shah M. R. , Akther Hossain A. K. M.

Materials Science Poland

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2013

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tom Vol. 31, No. 1

80-87

EN

Polycrystalline Ca1xLax(Ti0:5Fe0:5)O3 were prepared by the standard solid state reaction technique. Pellet shaped samples prepared from each composition were sintered at 1573 K for 5 h. The X-ray diffraction analysis indicated the formation of a single-phase orthorhombic structure. The lattice parameters as well as densities increased but the average grain sizes decreased with the increase of La content. The dielectric measurements were carried out at room temperature as a function of frequency and composition. The experimental results revealed that dielectric constant (e0) decreased but dielectric loss (tand) and ac electrical conductivity (sac) increased as frequency increased. The composition dependence of e0 and tand indicated that they decreased with the increase of La content. The sac was derived from the dielectric measurements and it is concluded that the conduction in the present samples is due to mixed polarons hopping.

5

Dielectric properties of Ba3Sr2DyTi3V7O30 ceramics

80%

Sahoo P. , Panigrahi A. , Patri S. , Choudhary R.

Open Physics

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2010

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tom 8

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nr 4

639-642

EN

A polycrystalline sample, Ba3Sr2DyTi3V7O30, with tungsten bronze structure was prepared by a mixed-oxide method at high temperature (950°C). Preliminary structural analysis of the compound showed an orthorhombic crystal structure at room temperature. Surface morphology of the compound was studied by scanning electron microscopy. The dielectric anomaly at 321°C may be attributed to the ferro-paraelectric phase transitions. This was also confirmed from the appearance of a hysteresis loop. The nature of variation of the ac conductivity and value of activation energy at different temperature regions, suggest that the conduction process is of mixed-type (i.e., ionic-polaronic and space charge generated from the oxygen ion vacancies).

6

Rola Profesora Andrzeja Bolewskiego w rozwoju nowoczesnej ceramiki w Polsce

80%

Stoch L. , Kurdowski W.

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2006

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tom R. 58, nr 2

73-75

7

Bioactive core material for porous load-bearing implants

80%

Sobieszczyk S. , Melaniuk M. , Zieliński A.

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tom Vol. 12, nr 3(33)

25-36

EN

So far state of knowledge on biodegradable materials is reviewed. Among a variety of investigated materials, those composed of polymers and ceramics may be considered as only candidates for a core material in porous titanium alloy. The collagen and chitosan among natural polymers, polyhydroxy acids among synthetic polymers, and hydroxyapatite and tricalcium phosphate among ceramics are proposed for further research. Three essential conditions for a core material are defined as: biodegradation rate "in vitro" and "in vivo" close to bone tissue in-growth rate, high compression strength and ability to form nanoporous open structure inside the material for vascularisation. Possible deposition techniques of a core material within the macropores of metallic scaffold include infiltration of titanium porous structure with polymer scaffold followed by precipitation of phosphate nanoparticles, and mixing of phosphate and polymers before deposition followed by controlled precipitation inside the pores.

8

Tribochemistry of ceramics

80%

Kajdas C.

|

1998

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tom z. 2

148-167

EN

Ceramics offer some advantages over conventional tribological mating elements.They are relatively inert,hard and more resistant to abrasive and erosive wear than typical alloy ateels. Ceramics can be used at much higher temperatures and corrode less than other regular metal tribological elements.Under boundary lubrication conditions, lubrication is dominated by tribochemical relatios.This is due to both metal and ceramic bearing systems,however, ceramic surfaces usually show less relation under such conditions.This paper aims at (a) presenting some tribochemical reactions which play an important role in the wear reduction of ceramics and (b) proposing a model of such relations.The proposed model is based on the negative-ion-radical action mechanism (NIRAM) of a lubr cant/environment component with the rubbing ceramic surface. Two reaction steps are considered. The first one includes reactions of a ceramic material ,e.g. silicon nitride, alumina, with water/oxygen molecules and the second step involves reactions of the modifited ceramic surface with additive or lubricant molecules. This mechanism clearly explains (i) formation of hydroxide groups on silicon nitride and alumina surfaces under boundary lubrication conditios and (ii) further reactios with selected lubricant components.

PL

Materiały ceramicane mają sporo zalet w porównaniu z konwencjonalnymi materiałamistosowanymi na węzły tarcia.Są one chemicznie obojętne, twarde i bardziej odporne na zużycie ścierne i erozyjne niż typowe stale stopowe. Mozna ich uzywać w znacznie wyzszych temparaturach-charakteryzują się znacznie mniejszą korozyjnościa w stosunku do metalowych części węzłów tarcia. W warunkach smarowania granicznego zarówno materiałów ceramicznych, jak i konwencjonalnych dominują reakcje tribochemiczne. W skojarzeniu materiałów ceramicznych zachodzi ich jednak znacznie mniej. Celem niniejszego artykułu jest (a) przedstawienie tych reakcji , które odgrywają decydująca rolę w zmniejszeniu materiałów ceramicznych oraz (b) zaproponowanie modelu przebiegu tych reakcji. Model ten zostanie oparty na mechaniźmie działania ujemnego rodnika (NIRAM) w układzie środek smarowy-otoczenie, na powierzchni tarcia materiału ceramicznego. takiego , jak np. azotek krzemu czy korund z cząsteczkami wody/tlenu.Etap drugi to reakcje zmodyfikowanej powierzchni ceramicznej z cząsteczkami środka smarowego lub dodatku.Przedstawiony mechanizm pozwala wyjaśnic (i) tworzenie się grup wodorotlenowych na powierzchni azotku krzemu w warunkach smarowania granicznego oraz (ii) kolejne reakcje z wybranymi składnikami środka smarowego.

9

Lu2O3:Eu, a new X-ray phosphor

80%

Zych E. , Hreniak D. , Stręk W.

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2002

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tom Vol. 20, No. 1

111-122

EN

Five specimens of Lu2O3:5%Eu were prepared using various synthesis techniques. One of the samples was in the form of a plate, air-sintered at 1775 °C. Radio- and photoluminescence spectra were recorded showing emission exclusively from the 5D0 level of Eu3+. The most intense radioluminescence, about 30% of that from standard CsI:Tl, was seen from the sintered ceramic sample. Excitation spectra suggest that some aggregation of Eu3+ ions take place in four of the five specimens. Some contamination of the four powdered samples with OH groups was found. Only the sintered material showing the most powerful emission was free of this problem.

10

Ceramika kondensatorowa na bazie Pb(Mg1/3Nb2/3)O3 z dodatkiem PbTiO3 i BaTiO3

80%

Kulawik J. , Szwagierczak D.

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2000

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tom Vol. 41, nr 5

13-16

PL

Badano warunki syntezy i spiekania oraz wlściwości dielektryczne ceramiki opartej na relaksorze Pb(Mg1/3Nb2/3)O3 (PMN) i jego roztworacg stałych z typowymi ferroelektrykami PbTiO3 (PT) i BaTiO3 (BT). Otrzymano trzy rodzaje ceramiki PMN, PMN--PT, PMN--PT--BT o wartościach maksymalnej przenikalności elektrycznej wynoszących odpowiednio: 12 000, 21 000, 8000 oraz temperaturach Curie --10°, 40° i 0°C. Ceramika PMN--PT--BT odznaczała się niskim temperaturowym współczynnikiem pojemności.

EN

The conditions of synthesis and sintering processes as well as dielectric properties of ceramics based on Pb(Mg1/3Nb2/3)O3 (PMN) and solid solutions of this relaxor with normal reffoelectric PbTiO3 (PT) and BaTiO3 (BT) were investigated. Three kinds of ceramics: PMN, PMN--PT and PMN--PT--BT were obtained. Dielectric constant values of these materials were 12 000, 21 000 and 8 000, respectively and Curie points --10°, 40° and 0°C, respectively. The PMN--PT--BT ceramics showed low temperature coefficient of capacitance.

11

Nowe kierunki w ceramice

80%

Mandecka-Kamień L. O.

Ceramika. Materiały Ogniotrwałe

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2000

|

tom R. 52, nr 1

35-36

12

Nowoczesna ceramika w zastosowaniu

80%

Rospond A. T. i. o.

Ceramika. Materiały Ogniotrwałe

|

2001

|

tom R. 53, nr 3

98-102

13

Piezoelectronic Materials on the Basisof Ferroelecric Ceramics

70%

Surowiak Z.

Molecular and Quantum Acoustics

|

2006

|

tom Vol. 27

265-284

EN

This paper presents fundamental properties of the ceramic ferroelectrics, place of the ferroelectrics in the family of crystalline materials, classification ferroelectrics (classical ferroelectrics CF or ferroelectric relaxors FR; displacive or order-disorder ferroelectrics), conventional processing of ferroelectric ceramics (process of synthesis by high temperature reaction in solid phase; calcining; sintering; poling) and some examples of practical ferroelectric ceramics (ferroelectrics for ceramics filters, underwater ultrasonic transducers, electroacoustics, high-voltage generators, etc.).

14

Badanie gęstości elementów murowych ceramicznych według PN-EN 772-13

70%

Babik W.

|

2005

|

tom R. 47, nr 2

7-9

15

PROBLEM BADAŃ NAD OSADNICTWEM WCZESNOLATEŃSKIM NA ŚLĄSKU NA PRZYKŁADZIE OSADY W KURZĄTKOWICACH, POW. OŁAWSKI

70%

Dulęba P. , Kosicki A.

Archeologia Polski

|

2017

|

tom 62

79-129

EN

The results of excavations on site 1 at Kurzątkowice, Oława dicstrict, make a very essential contribution to the studies on La Tène culture settlements on the area of modern Poland. Unearthed at the above mentioned site were relics of a small La Tène culture settlement in form of settlement features typical for that time, such as a shallow pit-house, pits of various purpose, clay-pit or pottery kiln. The material, found inside of these features, consisting almost exclusively of vessel pottery, indicates that the features may be dated to the early La Tène period. The importance of these discoveries is emphasised by the fact that the above mentioned features at Kurzątkowice are up till now the only known settlement features of La Tène culture on modern Polish lands which may be dated to phase LT B1-B2. Many attributes of the pottery workshop registered at Kurzątkowice indicate that the Celtic settlers from Lower Silesia were closely related to the lands of central Danube river basin, particularly to the area of Moravia.

16

Acoustic waves in ceramics with the electroinduced anisotropy

70%

Khakhomov S. A. , Barsukov S. D. , Semchenko I. V.

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2009

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tom Vol. 3, No. 4

191-201

EN

The effects related with formation of induced anisotropy in natural-isotropic media, have been studied already for a long time. These phenomena interest scientists first of all due to a rare opportunity of control of artificial anisotropy of media, and also due to an opportunity of the energy transfer to a propagating acoustic or an electromagnetic wave. The idea of the nonlinear interaction of an acoustic and rotating electric field for the observation of parametrical electro-acoustic effects in crystals belongs to V.N Belyi and B.B. Sevruk, and has been ascertained more than 20 years ago [1], [2]. Then this idea has being developed by physicists of the Gomel State University [3]-[8] where F.I. Fedorov, B.V. Bokut', and A.N. Serdyukov [9]-[10] created a scientific school in the field of optics and acoustics. Until the present time the opportunity of suppression of absorption of ultrasound by rotating an electric field and amplification of ultrasonic waves in a crystal in conditions of resonant interaction of an electric field with ultrasound [11]-[14] has been predicted. In this case, media with the induced rotating spatially homogeneous acoustic anisotropy represent an acoustic analogue of spatially periodic media, showing the effects characteristic for the last.

17

Properties of Ceramics Derived from Direct Observations of Crack

70%

Librant Z. , Boniecki M. , Gładki A. , Daszkiewicz M. , Galas J. , Rećko W.

|

1999

|

tom Vol. 47, nr 4

365-377

EN

A device was designed and constructed for direct observations of crack growth from notch or form Vickers indent made on the beam bent in a typical testing machine. The device, consisting of horizontal light microscope coupled with CCD camera, is fitted to ZWICK 1446 testing machine by the system of elevator stages driven by stepping motors. This enables precise movements of objective in x, y, z-direction, for adjustment, focusing and tracking on the beam side and bottom surface where the crack propagates. Measuring and registration picture system (framegrabber) is coupled with load and strain system of testing machine and both systems are aided by computer. Optical and electronic magnification is about to 250x. For the case of crack propagated in single-edge notched beam, directly measured crack length was compared with crack length calculated from compliance measurements.

18

Teresa Szałowska - ceramik.

70%

Puff Z.

|

2007

|

tom R. 58, nr 2

48-48

19

Czy decyzja KE zaszkodzi polskiej gospodarce?

61%

Grabowska M.

|

2007

|

tom R. 55, nr 2

28-30

PL

Decyzją z dnia 26 marca 2007 r. Komisja Europejska przyznała Polsce o ponad 26 procent mniej uprawnień, niż ubiegał się rząd. Decyzja Komisji jest niewątpliwie niekorzystna dla rozwoju polskiej gospodarki. Nie ma, bowiem w historii przypadku, aby wraz ze wzrostem gospodarczym, nie szły w parze wyższe emisje gazów.

20

Optimization the Injection Molding Process for Complex-Shaped Ceramic Orifices using Computer Simulation

61%

Kirkova O. , Tkachenko L. , Shtern M.

|

2009

|

tom Vol. 54, iss. 4

1045-1050

EN

The flow of the feedstock during its inject into a complex-shaped mould is studied. The model of nonlinear viscosity flow is used for the feedstock behavior analysis. The dependence of the shear viscosity effective coefficient on the powder concentration in the feedstock was determined by methods of computing micromechanics. The rheological equation of the feedstock contains the stuff (particles) concentration as a parameter. Using computer simulation, the optimization of the orifice for argon-arc welding as an example of a complex-shaped mold filling with feedstock (selection of the injection gate location) has been carried out. The results showed that the most uniform mold filling and the minimum number of defects were reached in case of the injection gate location at the narrow end of the orifice.

PL

Zbadano przepływ surowca podczas wtryskiwania do formy o złożonym kształcie. Do analizy zachowania surowca wykorzystano model nieliniowego przepływu lepkości. Zależność efektywnego współczynnika lepkości ścinania na stężenie proszku w surowcu została ustalona metodą komputerowego obliczania mikromechaniki. Równanie reologiczne surowca zawiera stężenie materiału (cząsteczek) jako parametr. Za pomocą symulacji komputerowej przeprowadzona została optymalizacja otworu dla spawania w osłonie argonu jako przykład wypełniania surowcem formy o złożonym kształcie (wybór umiejscowienia otworu wtryskowego). Wyniki wskazały, iż najbardziej jednolite wypełnianie formy i minimalna ilość defektów uzyskuje się w przypadku umiejscowienia otworu wtryskowego przy węższym końcu formy.