Wyniki wyszukiwania - Biblioteka Nauki

Nowa wersja platformy, zawierająca wyłącznie zasoby pełnotekstowe, jest już dostępna.
Przejdź na https://bibliotekanauki.pl

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: high-energy milling

Sortuj według:

Ogranicz wyniki do:

High-energy milling as a method for obtaining tetragonal form of PbO

100%

Staszewski M. , Myczkowski Z. , Bilewska K. , Sosiński R. , Lis M. , Czepelak M. , Kołacz D.

tom Vol. 52, nr 1

39--46

Purpose: The aim of this work was to verify the usefulness of high-energy milling, using electromagnetic mill, as a method for obtaining tetragonal (red) form of PbO, alternative to standard methods. Design/methodology/approach: Experiments were held to compare samples of the yellow form of PbO after milling in electromagnetic mill with the ones milled in high-energy planetary ball mill as a function of grinding medium (sticks or balls) to powder mass ratio, milling duration and instrumental conditions. Findings: Quantitative X-ray diffraction and analysis of granulation of mill products were applied. The characteristics of structural transitions of studied powder depending on milling conditions were defined. Practical implications: Utilization of electromagnetic mills was found to be suitable for milling of PbO. The speed and unit price of this process assure competitiveness of the method to standard methods. Tested method of high-energy milling assures possibility to supply, in certain conditions, good product. Obtained product may be used for manufacturing of minium. Originality/value: Optimum conditions of milling process and milling limitations were determined. Suggestions regarding optimization of mill construction were presented.

Hydrogen storage alloys prepared by high-energy milling

86%

Staszewski M. , Sierczyńska A. , Kamińska M. , Osadnik M. , Czepelak M. , Swoboda P.

Journal of Achievements in Materials and Manufacturing Engineering

2011

tom Vol. 44, nr 2

154--160

Purpose: The aim of this work was to investigate an efficiency of high-energy milling, as a method to obtain hydrogen storage alloys with good properties. Design/methodology/approach: Two classes of the alloys were studied: AB2 type with atomic composition of (Ti0.5 Zr0.5)(V0.68 Mn0.68 Cr0.34 Ni0.7) and AB5 type with atomic composition of (Ce0.63 La0.37)(Ni3.55 Al0.3 Mn0.4 Co0.75).The materials were prepared by arc melting and initially pulverized and afterwards subjected to wet milling process in a planetary mill. Findings Both initially obtained alloys had proper, single phase structure of hexagonal symmetry. However their elemental composition was greatly inhomogeneous. High-energy milling causes both homogenization of the composition and severe fragmentation of the powder particles, which after milling have mean diameter of about 3 μm (AB2 alloy) and below 2 μm (AB5 alloy). The morphology of obtained powders reveals that they tend to form agglomerates consisting of large number of crystallites. Mean crystallite sizes after milling are of about 4.5 nm and of 20 nm, respectively. The specific surface of the powders, measured using BET method, equals 8.74 m2 /g and 2.70 m2 /g, respectively. Research limitations/implications The results provide the information on the possibility of obtaining hydrogen storage alloys by high-energy milling and on the transformations taking place as a result of this process. Practical implications: The obtained powders can be used to produce the elements of hydrogen-nickel batteries and fuel cells, providing improved properties; especially extreme rise of the specific surface of the hydrogen storage material, in compare to the standard methods.

Influence of high-energy milling parameters on the synthesis of single-phase yttrium aluminium perovskite (YAP)

72%

Smoleń J. , Michalik D. , Plewa J. , Pawlik T.

2020

tom T. 72, nr 4

235--246

Yttrium aluminium perovskite with the formula YAlO3 (YAP) is one of the three oxides that occur in the Al2O3-Y2O3 system; YAM and YAG are stable coexisting phases of this system. YAP single crystals are known to be used as optical materials due to their favourable properties, especially when they are doped with rare earth or transition metal ions. The preparation of a monophase yttrium aluminium perovskite is a difficult task as the solid phase synthe- sis method leads to the formation of coexisting phases. High-energy milling is the most effective way to obtain a homogeneous mixture of yttrium and aluminium oxide powders (YAP precursors). In this work, different types of homogenization were compared and then the optimal parameters (rotational speed, milling ball size, milling time) influencing the phase composition and morphology of the product after synthesis were established. The X-ray diffraction (XRD) technique was used to study the phase composition and the morphology was characterized using a scanning electron microscope. The obtained results proved that the method of energy supply to the milled system has a significant impact on the course of synthesis and the morphology of the sintered product.

Perowskit itrowo-glinowy o wzorze YAlO3 (YAP) jest jednym z trzech tlenków występujących w układzie Al2O3-Y2O3; YAM i YAG to współistniejące stabilne fazy tego układu. Wiadomo, że monokryształy YAP są stosowane jako materiały optyczne ze względu na ich korzystne właściwości, zwłaszcza gdy są domieszkowane jonami pierwiastków ziem rzadkich lub metali przejściowych. Przygotowanie jednofazowego perowskitu itrowo-glinowego jest trudnym zadaniem, ponieważ metoda syntezy w fazie stałej prowadzi do powstania faz współistniejących. Najbardziej efektywnym sposobem otrzymywania homogenicznej mieszaniny proszków tlenków itru i glinu (prekursorów YAP) jest mielenie wysokoenergetyczne. W pracy porównano różne rodzaje homogenizacji, a następnie ustalono optymalne parametry (prędkość obrotowa, wielkość mielników, czas mielenia) wpływające na skład fazowy i morfologię produktu po syntezie. Do badania składu fazowego wykorzystano technikę dyfrakcji rentgenowskiej (XRD), a morfologię scharakteryzowano za pomocą skaningowego mikroskopu elektronowego. Uzyskane wyniki dowiodły, że sposób dostarczania energii do mielonego układu ma istotny wpływ na przebieg syntezy i morfologię spiekanego produktu.