Wyniki wyszukiwania - BazTech

1

Experimental investigation of particle size distribution and morphology of alumina-yttria-ceria-zirconia powders obtained via sol–gel route

Nakonieczny D. S., Antonowicz M., Paszenda Z. K., Radko T., Drewniak S., Bogacz W., Krawczyk C.

Biocybernetics and Biomedical Engineering

|

2018

|

Vol. 38, no. 3

535--543

EN

Background: Oxide-doped zirconia is currently commonly used ceramics in dental prosthetics. However, its use raises a lot of controversy. This is related to the stability of the zirconia metastable phases in the human mouth environment and it sensitivity for the so-called low-temperature degradation. A key way to avoid this type of negative phenomena is doping ZrO2 with selected metal oxide sand choosing appropriate methods for the synthesis of ceramic powders. Objective: The aim of this paper is to present investigations of modification and to analyse the influence of chemical composition and volume of parent-solvent for the morphology and thermal properties of ceramic powders prepared in a ZrO2-CeO2-Y2O3-Al2O3 system. Methods: The powders were obtained by using the sol–gel method in an inert gas atmosphere and ambient temperature using zirconium n-propoxide for this purpose. Morphology was examined by using scanning electron microscopy (SEM) and particle size distribution (PSD); thermal properties was evaluated using thermogravimetric analysis (TGA/DTA/DTG), and chemical composition was confirmed by using electron probe microanalysis (EPMA). Results: Depending from the volume of the CeO2 precursor solution of and regardless of the volume of the second oxide precursor, was observed difference in morphology of the obtained powders. Overall trend is related to reduce the size of agglomerates with an increase in the volume of the precursor of CeO2. Conclusions: The influence of various chemical compositions for morphology and thermal properties is negligible. In contrast, a clear correlation is observed between the volume of parent alcohol for both morphology and thermal properties. Use of sol–gel method to further research in view of these results appears to be appropriate.

2

Densymetryczna metoda wyznaczania punktu nasycenia wodnych roztworów siarczanu(VI) potasu

Bogacz W., Lemanowicz M., Obara A.

Przemysł Chemiczny

|

2017

|

T. 96, nr 2

458--459

PL

Przedstawiono wyniki eksperymentalnych badań dotyczących gęstości wodnych roztworów siarczanu(VI) potasu oraz punktu ich nasycenia. Pomiary wykonano w zakresie stężeń 10,7-14,5% mas. Wykazano, że dla zakresu nienasycenia gęstość roztworu można opisać liniową funkcją temperatury. Ponadto udowodniono, że istnieje specyficzny punkt (gęstość, temperatura), który pozwala na wyznaczenie temperatury nasycenia roztworu na podstawie pomiaru gęstości w punkcie nienasycenia.

EN

The d. of satd. aq. solns. of K₂SO₄ with concns. 10.7-14.5% by mass was measured sep. under thermostatic conditions at temps. near their satn. The d. of soln. in unsatn. range was described as a linear function of temp. Furthermore, the results revealed existence a sp. point with allows calcn. of satn. temp. of soln. based on a single d. measurement at any temp. below the satn. point.

3

Flocculation of flotation tailings using thermosensitive polymers

Bogacz W., Lemanowicz M., Gierczycki A., Mielańczyk A.

Chemical and Process Engineering

|

2017

|

Vol. 38, nr 3

379--392

EN

The key feature of thermosensitive polymers is the reversible transition between the hydrophilic and hydrophopic forms depending on the temperature. Although the main research efforts are focused on their application in different kinds of drug delivery systems, this phenomenon also allows one to precisely control the stability of solid-liquid dispersions. In this paper research on the application of poly(N-isopropylacrylamide) copolymers in processing of minerals is presented. In the experiments tailings from flotation plant of one of the coal mines of Jastrzębska Spółka Węglowa S.A. (Poland) were used. A laser particle sizer Fritsch Analysette 22 was used in order to determine the Particle Size Distribution (PSD). It was proved that there are some substantial issues associated with the application of thermosensitive polymers in industrial practice which may exclude them from the common application. High salinity of suspension altered the value of Lower Critical Solution Temperature (LCST). Moreover, the co-polymers used in research proved to be efficient flocculating agents without any temperature rise. Finally, the dosage needed to achieve steric stabilization of suspension was greatly beyond economic justification.

4

Phase composition and morphology characteristics of ceria-stabilized zirconia powders obtained via sol-gel method with various pH conditions

Nakonieczny D. S., Paszenda Z. K., Basiaga M., Radko T., Drewniak S., Podwórny J., Bogacz W.

Acta of Bioengineering and Biomechanics

|

2017

|

Vol. 19, no. 2

21--30

EN

High purity, fine crystalline, degradation-free at low temperature powders have attracted special interest in CAD/CAM prosthetic dentistry full ceramic restorations. This study reports the preparation and characterisation of zirconia-ceria (0.9ZrO20.1CeO2) powders. Materials were obtained from zirconium-n-alkoxide and cerium nitrate hexahydrate in the pH 2–4 and 8–10. Methods: Zirconia-ceria powders were obtained with the sol-gel method in a humid-free environment. Thermal analysis (TGA/DTA) of the as-prepared materials was made for an assessment of its behaviour at elevated temperatures. Specimens were dried at 80°C and calcinated in two stages: at 300°C with soaking time 2.5 h and 850°C with holding time 2.5 h, in order to evaluate the phase transformations. Thermal analyses of the as-dried powders were made for an assessment of its thermal behaviour during heat treatment up to 1000 °C. By X-ray diffraction (XRD), polymorphs of ZrO2 were identified. Additionally, scanning electron microscopy (SEM) and laser particle size distribution (PSD) were involved for characterisation of morphology of the powders. Results: We found a correlation between the pH of the colloidal system and the morphology of the as-obtained powders. Based on analysis (SEM,PSD), structures were identified known as soft and hard agglomerates. Conclusions: In summary, it can be stated differences were found between powder morphology depending on the used pH, which can be crucial for powder densification during sintering and compacting green bodies which, as a consequence, may be crucial for the lifetime of zirconia prostheses. Correlations between phase composition and pH are difficult to grasp, and require further more sophisticated studies.

5

Strefa metastabilna w krystalizacji

Bogacz W., Wójcik J.

Chemik

|

2014

|

Vol. 68, nr 3

198--204

PL

Chociaż strefa metastabilna jest istotnym zagadnieniem w krystalizacji przemysłowej, to wciąż jej definicja posiada pewne niejasności. W artykule przedstawiono wyniki badań polegających na określeniu temperatury nukleacji oraz szerokości strefy metastabilnej (przechłodzenie) dla roztworów chlorku potasu, azotanu (V) potasu i siarczanu (VI) potasu przy użyciu kalorymetru reakcyjnego Mettler Toledo RCle.

EN

The Metastable Zone (MSZ) is one of the most essential notions in industrial crystallization. However, its definitions have still some vagueness, and models to estimate the metastable limit (MSL) have not been matured enough to be used in practical operation. This paper presents the results of studies of determination the nucleation point and the MSZW of potassium chloride, potassium nitrate (V) and potassium sulphate (VI) solutions, using the Reaction Calorimeter Mettler Toledo RCle.

6

Badanie i obliczenia belek drewnianych wzmocnionych wklejanymi taśmami z włókien węglowych

Bogacz W., Lis Z., Łodygowski T., Rapp P.

Inżynieria i Budownictwo

|

2007

|

R. 63, nr 10

541-544

PL

W celu wzmocnienia lokalnie uszkodzonej strefy rozciąganej drewnianych belek zginanych zastosowano wklejane w drewno taśmy z włókien węglowych, które jako zbrojenie rozproszone przenoszą naprężenia rozciągające przy zginaniu. Przedstawiono inżynierską metodę obliczeń, badania doświadczalne oraz modelowanie numeryczne wzmocnionej strefy belki z wykorzystaniem metody elementów skończonych.

EN

The author concern yourself on purpose of strengthening local damages of timber stretching belts the pasted with timber bands of carbon fibers, which as reinforcement dispersed and transmits stresses evolved by crumple. The engineering method of calculation, examinational experiences and numerical modeling of strengthening areas of beams, using the method of finite elements units has been presented.

7

The tectogenesis of the Telfer gold-copper ore system in the Proterozoic Paterson orogen, north western Australia

Bogacz W.

Annales Societatis Geologorum Poloniae

|

2004

|

Vol. 74, No 1

95-121

EN

This paper reviews the tectonic genesis of the Telfer Au-Cu ore system in the Paterson Orogen, NW Australia. Most previous tectonic interpretations have focused on the regional compression-related tectonic processes. These interpretations, however, could neither explain the tectonic deformation nor the distribution of mineralisation. Tectogenetic analysis indicates that the Telfer deposit comprises two overlapping structural domains, both developed as a result of the upward propagation of basement fractures. The first domain represents a local compression-shear-related regime that initiated tectonic deformation and tectonic shortening of the host rock. This regime had a limited role in the mineralising processes. The second, more important regime for mineralisation control, is associated with local shear-extensional tectonic processes. At deposit scale, concurrent development of a normal dip-slip movement along the earlier formed bedding surfaces and the basement propagated steep reverse-slip shearing along NW-SE (S2) trending structures, parallel to the strike of the Paterson Orogen, are the most important tectonic processes of this domain. Bedding surface extensional openings and development of second order structures with N-S (E3) and NW-SE (E2) orientation controlled the tectonic genesis of the majority of orebodies and mineralised zones forming the Telfer ore system.