Wyniki wyszukiwania - BazTech

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Wykorzystanie metody zol-żel w modyfikacji materiałów ceramicznych nanocząstkami srebra

Rozmysłowska A., Jastrzębska A. M., Ciołek L., Olszyna A.

Szkło i Ceramika

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2018

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R. 69, nr 1

7--11

PL

W niniejszej pracy zaprezentowano stan badań na podstawie przeglądu literatury dotyczącej właściwości nanocząstek srebra (nano-Ag). Szczegółowo opisano właściwości korzystne z punktu widzenia zakładanych zastosowań, a także niekorzystne, powodujące wzrost zagrożenia związanego z cytotoksycznością i ekotoksycznością nano-Ag. Zaprezentowano przegląd literatury dotyczącej modyfikacji nano-Ag tlenkami metali oraz w kompleksowy sposób opisano różne metody wytwarzania nanomateriałów z tej grupy oraz układy wieloskładnikowe bioszkieł. Potwierdzono, że metoda zol-żel jest nie tylko mało skomplikowana z technologicznego punktu widzenia, ale także bardzo elastyczna, poprzez możliwość zastosowania różnych rodzajów prekursorów ceramiki i szerokiego wachlarza warunków prowadzonych procesów. Dane wskazują, że modyfikacje nanocząstek Ag tlenkiem glinu z wykorzystaniem metody zol-żel prowadzą do otrzymania ciekawych właściwości biologicznych, często znacząco różnych w porównaniu do wolnych nanocząstek Ag. Wciąż jednak trudnością pozostaje kontrola morfologii produktu końcowego i powtarzalność procesów zol-żel, ze względu na występujące zjawisko dyfuzji i transportu masy, które powoduje często rozrost wielkości wytwarzanych cząstek, a także powstawanie aglomeratów.

EN

This paper presents a review of the literature on the properties of silver nanoparticles (nano-Ag). Properties that are beneficial from the point of view of the intended applications have been described in detail, as well as undesired properties that increase the risk associated with the cytotoxicity and ecotoxicity of nano-Ag. A review of the literature concerning the modification of nano-Ag with metal oxides was also presented. Various methods for the production of nanomaterials from this group, as well as multi-component systems of bioglass, have been described in a comprehensive way. It was shown that the sol-gel method is not only not very complicated from a technological point of view, but also very flexible, through the possibility of using different types of ceramic precursors and a wide range of conditions of the processes. Data indicate that modifications of Ag with alumina particles using the sol-gel method lead to the production of interesting biological properties, often significantly different compared to free Ag nanoparticles. However, it is still difficult to control the final product morphology and the repeatability of the sol-gel processes because of the phenomenon of diffusion and mass transport often results in the size increase of the produced particles as well as the formation of agglomerates.

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Wybrane termofizyczne właściwości proszków cyrkonianowych na bazie pierwiastków ziem rzadkich typu RE2Zr2O7 (RE- Gd, La, Sm, Nd) przeznaczonych do natryskiwania cieplnego powłokowych warstw barierowych

Moskal G., Rozmysłowska A., Gazda A., Homa M.

Prace Instytutu Odlewnictwa

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2009

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T. 49, z. 4

15-26

PL

W artykule przedstawiono wyniki badań wybranych termofizycznych właściwości proszków ceramicznych typu RE2Zr2O7 (RE- Gd, La, Nd, Sm) przeznaczonych do natryskiwania plazmowego powłokowych barier cieplnych. W celach porównawczych przedstawiono również wyniki dla standardowego proszku typu ZrO2-8% wag. Y2O3 (Y8SZ). W celu wyznaczenia tych parametrów wykonano badania przewodności temperaturowej a (metodą laser-flash) oraz ciepła właściwego c[sub]p , stosując różnicową kalorymetrię skaningową DSC. Zakres temperatury pomiarów wynosił 25-1500°C. Badaniom poddano próbki spiekane w 1000°C. Przeprowadzone badania wykazały, że przewodność temperaturowa proszków typu RE2Zr2O7jest w temperaturze 1000°C niższa niż proszku Y8SZ. W zakresie temperatury 25-750°C wyższą przewodność temperaturową niż proszek Y8SZ wykazywał proszek typu La2Zr2O7. Najwyższą wartość ciepła właściwego wykazuje proszek cyrkonianowy Y8SZ, natomiast najniższą proszek na bazie cyrkonianu samaru.

EN

Paper presents results of investigations of selected thermophysical properties of ceramics powders RE2Zr207 (RE - Gd, La, Nd, Sm) type, used for thermal spray coatings. In comparison also standard powder of ZrO2-8%wg. Y2O3 (Y8SZ) was tested. Using laser-flash method thermal conductivity was designated and specific heat c[sub]p by differential scanning calorimetry (DSC) was determined. Measuring temperature varried from 25-1500°C. The samples tested were sintered at 1000°C. As a results of tests we obtain that thermal conductivity of RE2Zr2O7 powders at 1000°C is lower than Y8SZ. At temperature 25-750°C higher thermal conductivity was observed for La2Zr2O7 than for Y8SZ. The highest specific heat has zirconate powder Y8SZ, and the lowest- powder based on samarium zirconate.

3

Influence of heat treatment on microstructure of slurry aluminide coatings type TiAlSi obtained on TiAlCrNb alloy

Moskal G., Witala B., Rozmysłowska A.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 33, nr 2

204-210

EN

Purpose: Influence of heat treatment on microstructural changes in slurry TiAlSi coating deposited with 12.5% Si concentration on Ti48Al2Cr2Nb intermetallic alloy and investigation of the influence of Si addition on the structure of obtained coatings is a purpose of this paper. Design/methodology/approach: The research allowed identifying microstructural changes that took place during annealing at 950°C of the TiAlSi coating for 2 to 10h exposure in air. A scope of the research encompassed a microstructural analysis with the use of macro and micro investigation - LM, SEM microscopy, XRD phase analysis and EDS analysis. Findings: The investigation has shown that the thickness of the TiAlSi coatings in initial conditions and after a test was in a range from 30 to 40 ěm. The structure of the silicon-modified aluminide coatings is as following: the outer zone consisting of the TiAl3 phase and titanium silicides / the middle zone consisting of columnar titanium silicides in phase TiAl3 matrix / the inner zone consisting of TiAl2 phase. Basic changes were related to differences in thickness in sublayers. Research limitations/implications: The discussed research proves that main reason of much better protection of TiAlSi coated base alloy is related to high microstructure stability of Si modified in TiAl3 phases. In addition silicon decreases activity of titanium, and in consequence the susceptibility of Al to selective oxidation is much stronger. The presence of Si due to Ti-Si phase generation with high oxidation resistance is presented. Practical implications: The slurry method can be applied in aerospace and automotive industry as low-cost technology in production of aluminide coatings on intermetallics. Originality/value: New method of aluminide coatings deposition on TiAl alloys.

4

Thermal diffusivity of RE2Zr2O7 - type ceramic powders intended for TBCs deposited by APS

Moskal G., Witala B., Rozmysłowska A.

Archives of Materials Science and Engineering

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2009

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Vol. 36, nr 2

76-81

EN

Purpose: The aim of this paper is to provide overall characteristics of the Laser-Flash method and to determine the thermal diffusivity of powders intended for thermal spraying of thermal barrier coatings (TBC) of new type by air plasma spray (APS). Lanthanum, samarium, neodymium and gadolinium zirconates based powders with a pyrochlore structure and a general formula RE2Zr2O7 were used as the research material. Design/methodology/approach: The scope of the study encompassed thermal diffusivity tests of zirconium powders with the laser-flash method using the Netzsch LFA 427 apparatus for direct measurement of diffusivity. The scope of measured temperature ranged from 25°C to 1000°C (25, 250, 500, 750 and 1000°C). Every measurement point was repeated three times in order to obtain an average value. Findings: The studies conducted have enabled determining the value of thermal diffusivity of the material analyzed in the form of powder within a wide range of temperature. Research limitations/implications: The studies conducted suggest the necessity for verification of the obtained results for analogical coatings of the TBC type in order to determine the influence of the spraying process on the thermal diffusivity of the powders examined. Practical implications: The research results obtained provide a basis for further research on the base material and in particular, on the influence of porosity on thermal diffusivity. Originality/value: The original value presented in the paper is the information regarding the new type of ceramic materials intended for thermal spraying of TBCs.

5

Metallographic preparation of the conventional and new TBC layers

Moskal G., Witala B., Rozmysłowska A.

Archives of Materials Science and Engineering

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2009

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Vol. 39, nr 1

53-60

EN

Purpose: Verification of up-to-now used metallographic preparation of the TBC coating thermal barriers and adaptation of them to layers of new types, based on new ceramic compounds, sprayed on conventional high temperature creep resisting alloys by the APS method, is a purpose of this paper. New types of used ceramic powders are so called pyrochlores of a general formula RE₂Zr₂O₇. Design/methodology/approach: A scope of investigations comprised realization of a process of preparation of metallographic micro-sections, beginning from a cutting moment, through mounting, grinding and polishing. A standard method of preparation of micro-sections, typical for conventional layers was used and microstructural observation, from a point of view of presence of artefacts of mechanical origin was carried out. Findings: The carried out analysis allowed to compare methods of preparation of micro-sections and principles of preparation, used to assess the conventional TBC layers and relation them to barrier layers of new types. The carried out investigations showed that up-to-now used methods and procedures for the TBC layers, got by usage of conventional powders, are sufficient for layers of new types. Research limitations/implications: The carried out investigations suggest a necessity to verify the got results in a case of the TBC layers, sprayed by use of powders of pyrochlore structure of another type. Practical implications: The got results show a possibility to use up-to-now metallographic procedures for the TBC layers of new types. Originality/value: Information, concerning basic principles of microstructural assessment of layers of new types, sprayed by the APS method on high temperature creep resisting alloys, is an original value.