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1

Controlled precipitation of CaCO3 sub-micro crystals of well-defined structure in a multiphase system

Kędra-Królik K., Gierycz P., Bucki J. J.

Archives of Metallurgy and Materials

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2006

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Vol. 51, iss. 4

635-639

EN

In this paper we present the new method that allows obtaining of super fine calcium carbonate particles in a (CO2 – Ca(OH)2 – H2O) system. A new rotating disc reactor was employed as a processing unit to run this multiphase process. The device enables to control inter- and intraface mass and energy transfer as well as the macro- and micromixing effects in the reacting system. The system can be controlled by the rate of discs revolutions speed and mixing conditions in the system, reagents contact area or gas flow rate. The influence of different parameters on the reaction kinetics and precipitated powders properties were investigated. Crystallites and agglomerates morphology was examined with the Scanning Electron Microscopy (SEM). The testing with X-ray diffraction analysis confirmed that we have obtained a pure calcite, which is the most thermodynamically stable polymorph of CaCO3.

PL

W artykule przedstawiono nową metodę otrzymywania bardzo drobnych krystalitów węglanu wapnia w systemie (CO2 – Ca(OH)2 – H2O). Do realizacji tego wielofazowego układu wykorzystano reaktor z wirującym dyskiem, co umożliwia wpływanie na procesy transportu masy i energii. Możliwe jest także wykorzystanie efektów makro- i mikromieszania. Na zachowanie systemu istotny wpływ mają takie dające się kontrolować czynniki jak szybkość obrotowa dysków, powierzchnia kontaktu reagentów, czy wielkość przepływu gazu. W artykule pokazano wpływ poszczególnych czynników na szybkość reakcji. Kształt i wielkość zarówno pojedynczych krystalitów, jak i aglomeratów badano z wykorzystaniem skaningowego mikroskopu elektronowego. Badania dyfrakcji rentgenowskiej potwierdziły, że w przeprowadzonych procesach otrzymywano czysty kalcyt, będący najbardziej trwałą termodynamicznie odmianą CaCO3.

2

Estimation of glass forming ability of Ni-Ti-Zr system.

Morgiel J., Dutkiewicz J.

Inżynieria Materiałowa

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2001

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R. XXII, nr 5

651-654

EN

The microstructure and phases formed during the melt spinning of TiNiZr alloys from TiNi-NiZr and TiNi-TiNiZr phase diagram sections and TiNiZr-ZrNi-Zr2Ni eutectic were analyzed with TEM, SEM and XRD techniques. Ribbons from NiTi-NiZr sections containing 10 at.% Zr solidified with formation of columnar beta phase grains, while those containing 20 at.% Zr were amorphous with only minor amount of spherical beta phase crystallites. Ribbons from NiTi-NiTiZr section have either beta phase (at 10 at.% Zr) or amorphous (at 20 at.% Zr) matrix, but always with significant amount of other crystalline phases. Melt spinning of ribbons of composition close to the ternary TiNiZr-ZrNi-Zr2Ni eutectic allows also to obtain nearly amorphous ribbons with only small fraction of a metastable crystalline phase. Additionally, it was concluded that a position of ternary eutectic taken from the literature should be corrected toward higher nickel content.

PL

Mikrostruktura i skład fazowy szybkochłodzonych taśm ze stopów TiNiZr z przekrojów TiNi-NiZr, TiNi-TiNiZr oraz odpowiadających eutektyce TiNiZr-ZrNi-Zr2Ni były analizowane technikami skaningowej (SEM) i transmisyjnej (TEM) mikroskopii elektronowej oraz dyfrakcji rentgenowskiej (XRD). Taśmy z przekroju TiNi-NiZr zawierające 10%at. Zr krystalizowały tworząc kolumnową strukturę ziaren fazy beta, podczas gdy stopy z tego samego przekroju, ale o zwiększonej do 20at. % zawartości Zr miały strukturę amorficzną z niewielkim udziałem krystalitów fazy beta. Taśmy o składach z przekroju TiNi-TiNiZr posiadały strukturę albo fazy beta (10 at.% Zr) albo amorficzną (20 at.% Zr) ale zawsze ze znaczącym udziałem innych faz krystalicznych. Stop o składzie odpowiadającym eutektyce potrójnej również umożliwiał uzyskanie prawie całkowicie amorficznych taśm z niewielkim udziałem metastabilnej fazy krystalicznej. Dodatkowo stwierdzono, że pozycja eutektyki potrójnej TiNiZr-ZrNi-Zr2Ni znana z literatury powinna być skorygowana w kierunku wyższych zawartości niklu.

3

Elaboration of oxide nanocrystalline powders, microstructure and nanochemistry.

Laher-Lacour F., Kusinski J., Tebtoub M., Petot C., Petot-Ervas G.

Inżynieria Materiałowa

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2001

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R. XXII, nr 4

524-525

EN

Ultra fine powders were prepared either by freeze-drying (VO2, Y2O3-doped ZrO2, CeO2) or by the alum process (550 and 1650 ppm by wt MgO-doped Al2O3). X-ray diffraction and transmission electron microscopy analysis reveal that the as-prepared particles were well crystallized after thermal decomposition of the precursor. The average crystallite size is a function of the calcination temperature and of the amount of dopant; MgO acting as a grain growth inhibitor of the alumina grains, due likely to the high segregation of Mg at the periphery of the grains shows by XPS analysis.

4

XTEM-study of ceramic-metal joints: SiC/Mo, Si3N4/Mo.

Jezierska E., Jezierski S., Jakubowski J., Senkara J.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

723-726

EN

Joining of SiC and Si3N4 to molybdenum was carried out using Ag-Cu-In brazing alloy containing Ti as an active addition. In the present investigation a novel approach to the examination of ceramic-metal interfaces by means of cross-sectional transmission electron microscopy (XTEM) is described. The identification of the reaction products in an active zone of the joints was done and the detailed structure of multiphase interfacial region is presented. XTEM investigations were performed using Jeol microscopes; JEM 100B and JEM 3010, equipped with energy dispersive spectrometer (EDS). TEM samples were prepared by mechanical dimpling and ion beam thinning of real cross-sections of joints.

5

Wettability and interfaces in B13O2/Al system.

Sobczak N., Morgiel J., Kharlamow A., Ksiazek M., Radziwill W., Baliga S.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

754-757

EN

The wettability of B13O2 substrate by liquid aluminium was measured by the sessile drop method under vacuum at 1073-1273 K. A non-wetting to wetting transition was noted at about 1173 K. The oxy-redox reaction initiated at the B13O2 grain boundaries was found to be responsible for two phenomena in the Al/B13O2 system, i.e. wetting and infiltration of initially dense substrate by liquid Al. This reaction results in the formation of Al2O3 precipitates as well as AlB2 and AlB12 aluminium borides. The AlB12 crystallites are heavily faulted and contain numerous small inclusions of AlxOy or AlxOyBz type.

6

Quantitative characterisation of alumina scales on high temperature alloys by atomic force microscopy.

Czyrska-Filemonowicz A., Szot K., Wasilkowska A., Breuer U., Quadakkers W.J.

Inżynieria Materiałowa

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1998

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R. XIX, nr 4

1141-1146

EN

The formation of thin oxide films on {111} and {110} single crystal specimens of the Fe20Cr5Al based ODS alloy during the early stages of oxidation at temperatures up to 1000 degrees centigrade was quantitatively investigated by atomic force microscopy (AFM). The AFM results revealed the crystalline character of corrosion layer. The alumina scale morphology (height and grain size of crystallites) was slightly dependent on the crystallographic texture of the underlying bulk material. The results showed that AFM is promising technique for the quantitative characterization of the surface structure of oxide layers in the initial stages of oxidation processes.

7

Nanocrystalline Al-based alloys.

Latuch J., Kokoszkiewicz A., Matyja H.

Inżynieria Materiałowa

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1998

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R. XIX, nr 3

556-559

EN

The structure and mechanical properties determined by microhardness measurements of nanocrystalline Al86Y5Ni5TM4 (x = 4 at. %) alloys, where TM = Cu, Fe, were examined. The effect of replacement of Ni by TM elements on structure of the alloys obtained by rapid solidification and by isothermal annealing of initially fully amorphous alloys was investigated. This replacement extended the temperature region in which the A1 phase precipitates. The control of cooling rate and changes of annealing temperature caused the formation of nanoscale fcc-Al particles embedded in an amorphous matrix. The volume fraction of the nanophase particles and average size of Al-phase were calculated. The hardening effect induced by nanocrystallization was observed.