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ZrO2-CeO2 ceramic powders obtained from a sol-gel process using acetylacetone as a chelating agent for potential application in prosthetic dentistry

Nakonieczny D., Paszenda Z., Drewniak S., Radko T., Lis M.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 3

53--60

EN

Purpose: The main objective of this study was to obtain single-phase β-ZrO2 powders with so-called soft agglomerates reproducibile morphology with acetyl-acetone as a chelating-agent. To the best of our knowledge there is no avaiable data which determine the effect of acetyl acetone on the phase composition and morphology of ceria-doped ZrO2 powders for biomedical applications. Methods: Twenty variants of powders with different water to zirconia precursor and acetylacetone to zirconia precursor molar ratios were prepared. 0.9ZrO20.1CeO2 powders were obtained by a hydrolysis and condensation and further calcination of zirconium n-propoxide in a simple one-step sol-gel process. Influence of acetyloacetone to zirconia precursor on the phase composition ratio and water to zirconia precursor was investigated. Samples have been characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), thermal analysis (TGA/DTA) and scanning electron microscopy (SEM) measurements. Results: Ceramic powders prepared by sol-gel process, according to the various concentration of chelating agent and water show different morphology and phase composition. Conclusions: Higher molar ratios of AcAc in range with smaller amounts of water cause hard agglomerates, obtained powders are characterized by highly thermally stable behaviour and various phase composition. With higher molar ratios of water to zirconium-n-propoxide so-called soft agglomerates and one phase powders are obtained.

2

Characterization of magnesia-doped yttria-stabilized zirconia powders for dental technology applications

Nakonieczny D., Walke W., Majewska J., Paszenda Z.

Acta of Bioengineering and Biomechanics

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2014

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Vol. 16, no. 4

99--106

EN

Purpose: This paper is focused on the works concerning on preparing zirconium oxide ceramic blocks recommended for CAD/CAM systems used in prosthetic dentistry for manufacturing fixed prosthetic restorations. Methods: Zirconium-yttrium-magnesium mixed ceramic oxides were prepared by sol-gel method via hydrolysis and condensation of zirconium alkoxide precursor (zirconium (IV) propoxide) with yttrium and magnesium nitrates diluted in 2-propanol. The aim of this work it was to obtain 2% mol yttria stabilized zirconia ceramic powders with magnesium as an additional tetragonal ZrO2 phase stabilizer in amount between 2÷6% mol (with 2% variable). Prepared gels were dried (24 h in 65°C). Obtained powders were mixed with binder (carboxymethyl cellulose) and uniaxial pressed in to a specimens with diameter 38 x 22 x 6 mm. Afterwards green bodies were sintered in range of temperature between 1350-1550°C. Powders and blocks were characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Specific Area Measurement. Results: Highly homogeneous powders with a low open porosity, was obtained. Prepared blocks after sintering showed numerous cracks. Nevertheless blocks was fine grained and show quite reproducible chemical composition. Conclusion: A sol gel wet chemical route of powder synthesis allow to obtain high homogenous ceramic materials with inconsiderable amount of pores with low variation in a diameter. In spite of a reproducible synthesis methods of a ceramic powders, applied to prepare green bodies procedure and sintering manner do not allowed to obtain free from cracks zirconia ceramics blocks.

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Ocena stabilności termicznej proszków ZrO2 modyfikowanych tlenkami MgO oraz Y2O3

Nakonieczny D., Paszenda Z., Walke W.

Engineering of Biomaterials

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2013

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Vol. 16, no. 120

8--12

EN

Celem zrealizowanych badań było uzyskanie proszków ZrO2 zmodyfikowanych tlenkami itru i magnezu, które mogłyby być wykorzystane do przygotowania bloczków ceramicznych - półproduktu w procesie wytwarzania tzw. pełnoceramicznych protez stałych w protetyce stomatologicznej. Uzupełnienia pełnoceramiczne (full-ceramic restorations) w porównaniu do konwencjonalnych protez metalowo-ceramicznych (porcelain fused to metal) nie powodują metalozy oraz nie sprzyjają odkładaniu się płytki nazębnej i kamienia nazębnego. Rosnąca popularność protez pełnoceramicznych jest wynikiem upowszechnienia się technologii CAD/CAM, (wprowadzenie bardzo dokładnych frezarek numerycznych oraz oprogramowania dedykowanego dla gabinetów i laboratoriów stomatologicznych), dzięki której można precyzyjnie odwzorować warunki anatomiczne panujące w jamie ustnej pacjenta oraz wykonać funkcjonale uzupełnia protetyczne. Etapem limitującym dalsze stadia procesu wytwórczego oraz właściwości eksploatacyjne ZrO2 jest synteza proszków ceramicznych. Do przygotowania proszków wykorzystano „klasyczną” mokrą metodę zol-żel. Jako prekursor tlenku cyrkonu zastosowano propanolan cyrkonu. Jako prekursory domieszek tlenkowych wykorzystano heksahydraty azotanu itru oraz magnezu. Przydatność przygotowanych do prac proszków oceniono na podstawie analizy termicznej z wykorzystaniem termograwimetrii (TG). Materiały poddano badaniom ze względu na prawdopodobieństwo wystąpienia w składzie chemicznym sporządzonych próbek termolabilnego w zakresie temperatur spiekania wodorotlenku cyrkonu (Zr(OH)4, temperatura rozkładu 823 K) [1]. Przeprowadzona analiza pozwoliła stwierdzić nieznaczny, nie związany z dehydratacją ubytek masy próbek, co świadczy o braku obecności wodorotlenku cyrkonu w przygotowanych proszkach.

PL

The aim of presented study was to obtain zirconia powders modified with magnesium and yttrium oxides addition, which could be used for the preparation of the ceramic blocks - an intermediate product for manufacturing of the full ceramic fixed prosthetic restorations in prosthetic dentistry. Full ceramic restorations compared to so called conventional porcelain fused to metal restorations do not cause metallosis and prevent to the accumulation of plaque and tartar. The growing popularity of all-ceramic restorations is the result of spread of CAD / CAM technology, (introduction of high-precision milling machines and dedicated software for dentist and technicians la¬boratories) which allows to precisely reproduce the anatomical conditions prevailing in the patient's mouth and perform functional prosthetic restorations. Limiting step of the further process stages is the synthesis of ceramic powders. For the preparation of the ceramic powders the "classic" wet sol-gel method was used. As the zirconium oxide precursor zirconium isopropoxide was used. As the dopant oxide precursors were used yttrium and magnesium nitrate hexahydrates. Usefulness of prepared powders was characterized by thermogravimetry (TG). Materials were tested due to the likelihood occurrence of zirconium hydroxide in prepared samples chemical composition which is thermolabile in the range of sintering temperatures (Zr(OH)4, decomposition temperature 823 K) [1]. Results of the analysis led to the conclusion of presence of negligible, not associated with dehydration weight loss of the samples which show the absence of zirconium hydroxide in prepared powders.