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Wyświetlanie 1-4 z 4
Tytuł:
Influence of surgical drills wear on thermal process generated in bones
Autorzy:
Basiaga, M.
Paszenda, Z.
Szewczenko, J.
Kaczmarek, M.
Powiązania:
https://bibliotekanauki.pl/articles/306823.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
surgical drills
finite element method
thermal analysis
bone surgery
wiertło chirurgiczne
analiza termiczna
metoda elementów skończonych
chirurgia kostna
Opis:
The influence of the wear rate of drills used in bone surgery on the temperature distribution in the femur models (Sawbones) is presented in the paper. Surgical drills of diameter d = 4.5 mm and diverse edge geometry (90° and 120°) were selected for the study. In order to carry out thermal analysis with the use of finite element, experimental studies of wear process were necessary. These studies, among others, consisted in determination of average values of axial forces and cutting torques as a function of the number of drilled holes. The study showed an impact of the drill geometry on values that describe cutting process. It was found that the greatest values of torques and axial cutting forces occur in drills of point angle of 120°. Next, in order to determine the effect of wear rate on the generation of temperature in the cutting zone, thermal analysis of the drilling process using the finite element method was carried out. It was found that higher temperatures in the bone are observed for drilling with the use of the drill of point angle equal to 120°, as in the experimental study. For the tools of such edge geometry the wear of cutting edge is more intensive and the generated temperature in femur for the wear land VBB = 0.32 mm has reached the critical value associated with the process of thermal necrosis.
Źródło:
Acta of Bioengineering and Biomechanics; 2013, 15, 4; 19-23
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of magnesia-doped yttria-stabilized zirconia powders for dental technology applications
Autorzy:
Nakonieczny, D.
Walke, W.
Majewska, J.
Paszenda, Z.
Powiązania:
https://bibliotekanauki.pl/articles/307056.pdf
Data publikacji:
2014
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
stomatologia
protetyka
materiały protetyczne
metoda zol-żel
full ceramic restorations
prosthetic dentistry
sol-gel method
Zirconium Oxide
Opis:
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.
Źródło:
Acta of Bioengineering and Biomechanics; 2014, 16, 4; 99-106
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ZrO2-CeO2 ceramic powders obtained from a sol-gel process using acetylacetone as a chelating agent for potential application in prosthetic dentistry
Autorzy:
Nakonieczny, D.
Paszenda, Z.
Drewniak, S.
Radko, T.
Lis, M.
Powiązania:
https://bibliotekanauki.pl/articles/306436.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
proces zol-żel
metody rentgenowskie
analiza termiczna
ZrO2
protetyka
sol-gel process
X-ray Methods
Thermal Analysis
Prosthetic Dentistry
Opis:
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.
Źródło:
Acta of Bioengineering and Biomechanics; 2016, 18, 3; 53-60
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase composition and morphology characteristics of ceria-stabilized zirconia powders obtained via sol-gel method with various pH conditions
Autorzy:
Nakonieczny, D. S.
Paszenda, Z. K.
Basiaga, M.
Radko, T.
Drewniak, S.
Podwórny, J.
Bogacz, W.
Powiązania:
https://bibliotekanauki.pl/articles/306224.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
zol-żel
bioceramika
tlenek cyrkonu
właściwości termiczne
morfologia proszków
sol-gel
bioceramics
zirconia
oxide dopants
thermal properties
powder morphology
Opis:
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.
Źródło:
Acta of Bioengineering and Biomechanics; 2017, 19, 2; 21-30
1509-409X
2450-6303
Pojawia się w:
Acta of Bioengineering and Biomechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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