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1

Optical properties of polyetherketoneketone based indirect dental restorations veneered with composite

Alsadon Omar, Wood Duncan, Patrick David, Durgesh Bangalore, Pollington Sarah

Polimery

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2022

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Vol. 67, nr 4

141--148

EN

In this study, the optical properties of indirect dental restorations based on polyetherketoneketone (PEKK), zirconia (YZ), and nickel-chromium (Ni-Cr) veneered with composite were compared. Based on the spectral reflectance, the CIE L*a*b* color coordinates, the color difference (ΔE), the opacity and the translucency parameter (TP) were determined using a spectrophotometer equipped with a D65 illuminant. The PEKK and Ni-Cr groups demonstrated similar CIE L*a*b* color values on white and black backgrounds. However, the zirconia group on a white backgrounds showed a slight shift in values towards red-yellow shades. The highest recorded ΔE values were 1.3 and 1.61 between PEKK and YZ groups, and Ni-Cr and YZ groups respectively. The opacity and translucency (TP) parameters were consistent with the spectral reflectance data, with the Ni-Cr and PEKK groups being completely opaque (100% and 0 TP). It has been shown that the use of the same indirect light-cured composite veneer with different substructure materials has no clinical effect on the esthetics of the final restoration.

PL

Porównano właściwości optyczne pośrednich uzupełnień protetycznych na bazie polieteroketonoketonu (PEKK), tlenku cyrkonu (YZ) i niklu-chromu (Ni-Cr) licowanych kompozytem. Na podstawie współczynnika odbicia spektralnego określono współrzędne koloru CIE L*a*b*, różnicę koloru (ΔE), nieprzezroczystość i parametr przezierności (TP). Współrzędne koloru grupy PEKK i Ni-Cr wykazywały podobne wartości koloru CIE L*a*b* na białym i czarnym tle. Natomiast w przypadku YZ na białym tle stwierdzono niewielkie przesunięcie wartości w kierunku odcieni czerwono-żółtych. Najwyższe odnotowane wartości ΔE wyniosły 1,3 i 1,61 odpowiednio dla grup PEKK i YZ oraz Ni-Cr i YZ. Parametry nieprzezroczystości i przezierności były zgodne z danymi spektralnego współczynnika odbicia, przy czym grupy Ni-Cr i PEKK były całkowicie nieprzezroczyste (100% i 0 TP). Wykazano, że zastosowanie tej samej pośredniej światłoutwardzalnej licówki kompozytowej z różnymi materiałami podbudowy nie ma klinicznego wpływu na estetykę ostatecznego uzupełnienia.

2

Microstructure, mechanical performance and wear behavior of AZ91D-B4C-ZrO2 hybrid composites

Gali Singaiah, Prattipati Prasanna

Composites Theory and Practice

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2022

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R. 22, nr 4

219--224

EN

The stir casting process was used to produce AZ91D magnesium alloy hybrid composites reinforced with boron carbide (B4C) and zirconia (ZrO2). The microstructure of the composites revealed heterogeneity in the reinforcing phase distribution. A pin-on-disc test was conducted to investigate the tribological features of the fabricated composites such as the wear and coefficient of friction under dry sliding conditions. Increased hardness was observed for the composites due to the dispersion of the reinforcement. The composite with 2 wt.% ZrO2 + 3 wt.% B4C exhibited a higher yield strength and increased tensile strength compared with the other specimens. It was observed that the addition of B4C and ZrO2 improved the wear resistance of the AZ91D alloy as reflected by the lower wear rate. Among all the specimens, the composite reinforced with 2 wt.% ZrO2 + 3 wt.% B4C has the highest wear resistance. Hence, it can be concluded from the present work that incorporating B4C and ZrO2 is a promising way to achieve better mechanical properties and wear properties of AZ91 composites.

3

Zastosowanie dwutlenku cyrkonu jako materiału konstrukcyjnego

Blok Zbigniew, Kluczowska Agnieszka, Pelc Katarzyna, Strzępek Krzysztof, Pięciak Leszek, Sieroń Katarzyna

Rynek Energii

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2021

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Nr 6

70--75

PL

Materiały ceramiczne można ogólnie sklasyfikować jako ceramikę tradycyjną i ceramikę inżynieryjną. W zależności od zastosowania ceramika inżynieryjna dzieli się na ceramikę konstrukcyjną i funkcjonalną. Do ceramiki inżynieryjnej zaliczamy dwutlenek cyrkonu częściowo stabilizowany tlenkami itru, magnezu lub wapnia. Dwutlenek cyrkonu jest materiałem ceramicznym, który znajduje zastosowanie w wielu dziedzinach techniki jako materiał konstrukcyjny o bardzo korzystnych właściwościach. Na uwagę zasługuje jego wysoka wytrzymałość i twardość. W IEn CEREL wykonano badania właściwości różnych rodzajów dwutlenku cyrkonu. Materiały te są stosowane w CEREL do produkcji elementów maszyn. Przedstawiono przykłady ich zastosowań i korzyści jakie uzyskano dzięki ich wdrożeniu.

EN

Generally, ceramic materials are usually classified as traditional and engineering ceramics. Based on their applications, engineering ceramics are classified as structural and functional ceramics. One of the example of structural ceramics is zirconia dioxide partially stabilized with various oxides. These materials have many advantageous properties: high mechanical strength, high hardness and high Young’s modulus. CEREL department applies these materials for various elements of machines. This article presents main properties of zirconia ceramics made by CEREL and examples of applications of these materials.

4

Investigation the effect addition of nano Al2O3 on microstructure of Yttria tetragonal Zirconia polycrystalline ceramic

Alshaibani I.J.

Archives of Materials Science and Engineering

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2021

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Vol. 107, nr 2

49--55

EN

Purpose: This research aimed to prepare tetragonal zirconia polycrystals powder by coprecipitation method and study effects of addition of different amounts of nano Al2O3 (1, 2 and 4) wt.% on its microstructure and mechanical properties of (5Y-TZP) composite. Design/methodology/approach: The powder was uniaxial pressed at a pressure of 150 MPa and held for 60 s, and sintered at the 1500°C, held for two hours and then cooling down at 5°C/min to room temperature. Microhardness and fracture toughness tests were utilized to evaluate the mechanical properties of yttria tetragonal zirconia polycrystal composite. The microstructure has been observed using field emission scanning electron microscopy(FESEM). Findings: The results showed an addition of nano Al2O3 has a great influence on hardness and microstructure, the increase in Vicker's microhardness of composite samples with the increase in the nano Al2O3 wt.% and microstructure were characterized with homogeneous zirconia distribution, grain growth destruction with the increasing percentage of nano Al2O3. The most important influence is the enhancing of the densification process as the porosity decreased. The highest hardness and maximum fracture toughness were recorded at 4 wt.% nano Al2O3. Research limitations/implications: Ceramic matrix composites are developed to overcome the brittleness of ZrO2 and the low toughness of alumina by formation, a large difference of elastic behavior between matrix and particles(dispersion phase )which disturbs the stress field as a dislocation comes near a particle. Practical implications: Zirconia has mechanical properties similar to those of stainless steel. Yttria-stabilized tetragonal Zirconia (Y-TZP) is growing used in dentistry due to its good mechanical properties such as hardness and fracture toughness. Thus, controlling of microstructure by adding nanoalumina plays an important role in enhancing these properties. Originality/value: Study the adding bitty percentage from nano alumina on microstructure and mechanical properties of (5Y-TZP) ceramic.

5

Synthesis of vanadium-enriched oxide materials via modified sol-gel route with the use of waste solutions contaminated with vanadium ions

Weidner Ewelina, Piasecki Adam, Siwińska-Ciesielczyk Katarzyna, Jesionowski Teofil, Ciesielczyk Filip

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 6

60--75

EN

In this study, the synthesis of zirconia as well as zirconia enriched with vanadium by modified sol-gel method was presented. The modification of the method was based on the replacement of the traditional basic promoter of hydrolysis, which is ammonia, with sodium hydroxide solution. The most favorable conditions for the synthesis of zirconium with a new hydrolysis promoter were selected. A comparative analysis of ZrO2 obtained using various hydrolysis promoters was performed. Both materials exhibited almost the same physicochemical properties, which proves that in this case the nature of the hydrolysis promoter used in sol-gel route does not significantly affect the properties of the ZrO2. Then, synthesis of ZrO2/V systems was carried out using model and real solutions containing vanadium ions as hydrolysis promoters. The solutions formed after vanadium catalyst leaching were used as real solutions. The effect of vanadium concentration and the presence of impurities on the final physicochemical properties of the obtained hybrid materials were investigated via scanning electron microscopy (SEM), dynamic light scattering (DLS), energy-dispersive X-ray microanalysis (EDS), Fourier transform infrared spectroscopy (FT-IR), low-temperature nitrogen sorption (BET), thermogravimetric analysis (TGA). The analysis of the obtained results allows to state that the developed technique for the synthesis of ZrO2 and ZrO2/V systems, using a modified sol-gel method, enabled the production of attractive materials.

6

Skład fazowy kompozytu Y-TZP/ZrO2 a temperatura

Wojteczko Kamil, Wojciechowski Kamil, Bućko Mirosław M., Haberko Krzysztof

Materiały Ceramiczne

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2020

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T. 72, nr 2

123--131

PL

Przygotowano mieszaninę nanometrycznego proszku roztworu stałego Y2O3 (8% mol.) w ZrO2 z sub-mikrometrowym proszkiem czystego ZrO2. Oba proszki różniły się nie tylko wielkością cząstek, lecz również ich kształtem. Pierwszy składał się z cząstek izometrycznych otrzymanych przez hydrotermalną obróbkę (240 °C, 4 h) współstrąconego żelu Y2O3-ZrO2 w środowisku wody destylowanej. Taka sama technika krystalizacji, lecz w środowisku wodnego roztworu NaOH (4M) zastosowana w przypadku czystego żelu ZrO2 prowadziła do krystalizacji wydłużonych cząstek dwutlenku cyrkonu. Średni skład mieszaniny obu proszków odpowiadał zawartości 3% mol Y2O3. Charakterystyka proszków polegała na pomiarze ich powierzchni właściwej, obserwacji pod transmisyjnym mikroskopem elektronowym i rozpoznaniu składu fazowego metodą dyfrakcji rentgenowskiej. Tę ostatnią metodę zastosowano do rozpoznania zmian składu fazowego wyprasek mieszaniny proszków podczas ich ogrzewania w piecu dylatometru. Pomiary skurczu wyprasek wykazały istotną różnicę w zachowaniu się mieszaniny obu proszków i nanometrycznego proszku 8% mol. Y2O3-ZrO2. Obserwacje pod skaningowym mikroskopem elektronowym spieków wykazały obecność relatywnie dużych ziaren wywodzących się z wydłużonych cząstek czystego ZrO2 w osnowie sub-mikrometrycznych cząstek wyjściowego roztworu stałego Y2O3 w ZrO2. Analiza EDS wykazała większą zawartość itru w tych pierwszych niż w drugich. Podjęto próbę wyjaśnienia tego zjawiska.

EN

Mixture of the powders essentially differing of their particles morphology and size were applied to prepare polycrystals in the Y2O3-ZrO2 system. The yttria-zirconia solid solution nanometric powder of Y2O3 concentration of 8 mol% was prepared by the hydrothermal treatment of the yttria-zirconia co-precipitated gel at 240 °C for 4 h in distilled water. The pure zirconia gel was also subjected to the hydrothermal treatment but in this case in NaOH aqueous solution (4 M). The latter procedure resulted in the sub-micrometric elongated particles. The mean final composition of the mixture corresponded to 3 mol% Y2O3 content. Phase composition of the powders was characterised by the measurements of their specific surface area and by the X-ray diffraction. The latter method was useful to follow phase changes during sintering of the powder mixture using compacts heat treated in the dilatometer furnace. The dilatometric measurement revealed essential difference of the shrinkage run vs. temperature of the powder mixture and the nanometric yttria-zirconia solid solution powder. The SEM micrographs show existence of the relatively large grains surrounded by the sub-micrometric matrix. The latter originating from the nanometric Y2O3-ZrO2 show lower yttria concentration than the former ones. An attempt of explanation of this behaviour is presented.

7

The abrasive wear susceptibility of innovative ATZ type composites produced by sintering mix of zirconia powders with different chemical composition

Grabowy Marek, Wojteczko Kamil, Wojteczko Agnieszka, Dębiński Piotr, Almansour Sana Ahmad, Minh Le Huy, Bućko Mirosław M., Pędzich Zbigniew

Composites Theory and Practice

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2020

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R. 20, nr 1

11--16

EN

Composites based on tetragonal zirconia polycrystals modified with corundum inclusions ATZ (alumina toughened zirconia), are one of the basic and more commonly used ceramic structural materials. They are used especially willingly as parts of devices and machinery working in both dry and wet wear conditions in the presence of hard abrasive particles intensifying wear processes. The mechanical properties of such composites, strength and fracture toughness mainly, strongly depend on their chemical and phase compositions as well as microstructure. The aim of the present work was to investigate an innovative type of ATZ material composed of a mixture of two ZrO2 powders with different chemical composition and a small addition (2.3 vol.%) of nanometric corundum powder. The proper composite materials additionally contained 10 or 20 vol.% commercially available corundum particles. Tests were carried out on the mentioned materials for abrasive wear susceptibility according to the ASTM Dry Sand Test and ASTM Miller Test, using silicon carbide particles as the abrasive medium. As a reference materials, typical TZP (tetragonal zirconia polycrystals) material prepared using commercial powder and ZTA (zirconia toughened alumina) material containing 5 vol.% zirconia dispersed in an alumina matrix were used. The obtained results allowed the usability of the individual composite materials to be verified under various operating conditions.

PL

Kompozyty na osnowie tetragonalnego dwutlenku cyrkonu, modyfikowane wtrąceniami korundowymi (alumina toughened zirconia, ATZ), są jednym z podstawowych i częściej stosowanych ceramicznych tworzyw konstrukcyjnych. Szczególnie chętnie są stosowane jako elementy maszyn i urządzeń pracujące w warunkach tarcia suchego lub w obecności wody, często w obecności twardych cząstek intensyfikujących procesy zużycia. Właściwości mechaniczne tego typu kompozytów, głównie wytrzymałość i odporność na kruche pękanie, silnie zależą od ich składu chemicznego, fazowego i mikrostruktury. Celem niniejszej pracy było zbadanie innowacyjnego typu kompozytów ATZ, w którym jako osnowę zastosowano mieszaninę dwóch proszków ZrO2 o różnym składzie chemicznym z niewielkim (2,3% obj.) dodatkiem nanometrycznego proszku korundu. Właściwe materiały kompozytowe zawierały ponadto komercyjnie dostępne ziarna korundu w ilości 10 lub 20% obj. Wykonano dla tych materiałów testy podatności na zużycie ścierne luźnym ścierniwem węglika krzemu według norm ASTM - Dry Sand Test i Miller Test. Jako materiałów odniesienia użyto typowego materiału TZP (tetragonal zirconia polycrystals) uzyskanego z komercyjnego proszku oraz materiału typu ZTA (zirconia toughened alumina). Otrzymane wyniki pozwoliły zweryfikować użyteczność poszczególnych typów kompozytu w różnych warunkach pracy.

8

Tribological Properties of Al2O3/ZrO2 Sintered Ceramics

Wiązania Grzegorz, Kot Marcin, Wojteczko Agnieszka, Pędzich Zbigniew

Tribologia

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2019

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nr 1

67--72

EN

The paper presents mechanical and tribological properties of Al2O3/ZrO2 composite sinters with different proportions of Al2O3 and ZrO2 phases. These materials are commonly used in dry friction contact due to relatively low manufacturing costs of even complex shapes of products and the possibility of working at elevated temperatures. The tests were carried out by the ball-on-disc method at temperatures of 20, 150, 300, and 500°C. A ball made of Al2O3 was used as a counterpart. The results were compared with the following sintered mono-phase materials: Al2O3 (alumina) and tetragonal yttria-stabilized ZrO2 polycrystallines (Y-TZP). The tests showed the significantly better properties of composite materials.

PL

W pracy przedstawiono właściwości mechaniczne i tribologiczne spieków kompozytowych Al2O3/ZrO2 o różnej proporcji faz Al2O3 i ZrO2. Są to materiały chętnie stosowane w węzłach tarcia suchego ze względu na relatywnie niskie koszty wytwarzania nawet skomplikowanych kształtów wyrobów i możliwość pracy w podwyższonych temperaturach. Testy przeprowadzono na stanowisku z węzłem tarcia ball-on-disc w temperaturach 20, 150, 300 i 500°C, jako przeciwpróbkę zastosowano kulkę wykonaną z Al2O3. Wyniki badań porównywano z wynikami badań spieków wytwarzanych z materiałów jednofazowych: α- Al2O3 (korund) i tetragonalnych polikryształów ZrO2 stabilizowanych tlenkiem itru (tzw. Y-TZP). Badania wykazały znacząco lepsze własności materiałów kompozytowych.

9

Właściwości mechaniczne kompozytów typu ATZ otrzymanych w procesie spiekania mieszaniny proszków dwutlenku cyrkonu o różnym składzie chemicznym

Grabowy Marek, Maciewicz Karolina, Łuszcz Maciej, Pędzich Zbigniew, Bućko Mirosław M.

Materiały Ceramiczne

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2019

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T. 71, nr 3

286--294

PL

Kompozyty na osnowie tetragonalnego dwutlenku cyrkonu, zawierające wtrącenia korundowe (alumina toughened zirconia, ATZ), są jednym z podstawowych i częściej stosowanych ceramicznych tworzyw konstrukcyjnych. Właściwości mechaniczne tego typu kompozytów, głównie wytrzymałość i odporność na kruche pękanie, silnie zależą od ich składu chemicznego, fazowego i mikrostruktury. Celem niniejszej pracy było otrzymanie kompozytów ATZ w procesie spiekania mieszaniny dwóch proszków ZrO2 o różnym składzie chemicznym z niewielkim (1.5 % mas.) dodatkiem nanometrycznego proszku korundu, a także określenie ich mikrostruktury i podstawowych właściwości mechanicznych. Użyto nanometrycznego proszku czystego dwutlenku cyrkonu i proszku zawierającego 4% mol. tlenku itru, a ich ilości w mieszaninie z nanokorundem dobrano tak, aby końcowy produkt miał nominalnie 3% mol. Y2O3. 1,5% mas. nanometrycznego tlenku glinu Do takiej mieszaniny proszków dodano 10% lub 20% obj. proszku submikronowego korundu po czym wypraski spiekano w 1450 °C przez 2 h. Tak otrzymany materiał cechował się wyższą wartością współczynnika krytycznej intensywności naprężeń, lecz niższą wytrzymałością na zginanie w stosunku do spieku otrzymanego w tych samych warunkach z jednofazowego proszku. Obecność ziaren tlenku glinu w każdym przypadku podnosiła zarówno odporność na kruche pękanie, jak i wytrzymałość.

EN

Composites based on tetragonal zirconia, containing corundum inclusions (alumina toughened zirconia, ATZ), are one of the basic and more commonly used ceramic structural materials. The mechanical properties of this type of composites, mainly strength and fracture toughness, strongly depend on their chemical and phase composition as well as their microstructure. The purpose of this work was to obtain ATZ composites in the sintering process of two ZrO2 powders with different chemical composition with a small (1.5 wt%) addition of nanometric corundum powder, as well as to determine their microstructure and basic mechanical properties. Nanometric powders of pure zirconia and zirconia containing 4 mol% yttrium oxide were used, and their amounts in the mixture with nanocorundum were selected so that the final product had a nominal 3 mol% Y2O3. To this powder mixture, 10% or 20% by volume of submicron corundum powder was added, after which the compacts were sintered at 1450 °C for 2 h. The material obtained in this way was characterized by a higher value of the critical stress intensity factor, but a lower bending strength in relation to the sintered body obtained under the same conditions from a single-phase powder. The presence of alumina grains in each case increased both fracture toughness and strength.

10

Friction and wear of composites in alumina/zirconia system

Wojteczko A., Wiązania G., Kot M., Pędzich Z.

Composites Theory and Practice

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2018

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R. 18, nr 1

51--56

EN

The paper presents the results of friction and abrasive wear measurements of composites in the α-alumina/tetragonal zirconia system. Two types of materials with mutually interpenetrating phases in a continuous manner were investigated. Pure alumina and zirconia samples were used as the reference materials. Ball-on-disc tests were conducted at 20 and 500°C. An alumina ball was applied as the counterpart. The tests showed that the composites have a significantly reduced wear rate and friction coefficient when compared to monophasic materials. Improvement of the properties was noticeable especially at the elevated temperature.

PL

Przedstawiono wyniki pomiarów tarcia oraz zużycia ściernego kompozytów z układu tlenek glinu/tetragonalny dwutlenek cyrkonu. Badano dwa typy materiałów z fazami wzajemnie przenikającymi się w sposób ciągły. Próbki z czystego tlenku glinu oraz tlenku cyrkonu zostały użyte w badaniu jako materiały odniesienia. Badanie metodą Ball-on-Disc przeprowadzono w temperaturach 20 oraz 500°C. Kula z tlenku glinu została użyta jako przeciwpróbka. Testy wykazały, że kompozyty mają wyraźnie obniżony współczynnik tarcia oraz podatność na ścieranie w porównaniu do materiałów jednofazowych. Poprawa właściwości była zauważalna szczególnie w podwyższonych temperaturach.

11

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

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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.

12

Diacryloyl Derivative of Mannitol - Synthesis and Application in Gelcasting of Al2O3-ZrO2 Composites

Wiecinska P., Kubica D., Pietrzak E., Sakowicz A., Prokurat N., Antosik A.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

859--865

EN

The aim of research was the elaboration of the synthesis of new organic monomer applicable in gelcasting. The substance named 3,4-di-acryloyl-D-mannitol which contains two acryloyl groups and four hydroxyl groups in its molecule has been synthesized. The monomer has been then applied in the preparation of Al2O3-ZrO2 composites by gelcasting and subsequent sintering. Rheological properties of ceramic suspensions have been examined, as well as the properties of green and sintered bodies. SEM observations allowed to determine the distribution of zirconia grains in alumina matrix. Density, Vickers hardness and fracture toughness of ZTA composites have been measured. The new monomer, that is diacryloyl derivative of mannitol, is less sensitive to the oxygen inhibition than commonly used in gelcasting and commercially available 2-hydroxyethyl acrylate.

13

In situ cerium hexaaluminate platelets reinforcement of ED-machinable ZTA-TiC ceramics

Gommeringer A., Schmitt-Radloff U., Kern F., Gadow R

Materiały Ceramiczne

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2017

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T. 69, nr 1

4--9

EN

Electrical discharge machinable ceramics open new applications fields by combining good mechanical properties such as high strength, hardness, abrasion resistance and high temperature resistance with the possibility to produce complex shape customized components. Alumina based ceramics with dispersions of zirconia and a conductive refractory carbide offer enhanced hardness and abrasion resistance compared to other ED-machinable ceramics based on silicon nitride or Y-TZP based compounds, however only a moderate toughness. In the present study cerium hexaaluminate (CA6) platelets were introduced in the material system of zirconia toughened alumina with 24 vol.% titanium carbide by in situ reaction sintering to further improve the fracture resistance. With addition of CA6 the fracture resistance and strength increases while hardness and electrical conductivity were incrementally reduced. CA6 addition leads to a slight reduction in material removal rate in die sinking EDM and reduction of roughness in machined surfaces.

PL

Elektroerozyjnie obrabialna ceramika otwiera nowe pola zastosowań poprzez połączenie dobrych właściwości mechanicznych takich jak wysoka wytrzymałość, twardość, odporność na ścieranie i wysoka odporność temperaturowa z możliwością wytwarzania złożonego kształtu komponentów stosownie do wymagań klienta. Ceramika oparta na tlenku glinu zawierająca dyspersje tlenku cyrkonu i przewodzącego węglika ogniotrwałego oferuje podwyższoną twardość i odporność na ścieranie w porównaniu z pozostałą ceramiką obrabialną elektroerozyjnie opartą na azotku krzemu lub Y-TZP, ale jedynie umiarkowaną odporność na pękanie. W prezentowanych badaniach do układu materiałowego tlenku glinu wzmocnionego tlenkiem cyrkonu zawierającego 24% obj. węglika tytanu wprowadzono płytki sześcioglinianu ceru (CA6) drogą in situ spiekania reakcyjnego, aby poprawić odporność na pękanie. Wraz z dodatkiem CA6 zwiększyły się odporność na pękanie i wytrzymałość, podczas gdy twardość i przewodność elektryczna zostały przyrostowo zredukowane. Dodatek CA6 prowadzi do nieznacznego zmniejszenia szybkości usuwania materiału w trakcie elektrodrążenia wgłębnego EDM i redukcji chropowatości obrabianej powierzchni.

14

Trends and perspectives in modification of zirconium oxide for a dental prosthetic applications – A review

Nakonieczny D. S., Ziębowicz A., Paszenda Z. K., Krawczyk C.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 1

229--245

EN

Full-ceramic dental restorations made from ZrO2 have become increasingly popular due to their aesthetics and mechanical strength, and are gradually replacing prostheses made of porcelain fused to metal. Nevertheless, due to the variability in the physicochemical properties in a wet environment at elevated temperature, zirconia is quite a controversial material, the use of which in the environment of the mouth is questionable and raises many concerns. The reason for the variability in the physicochemical changes is the martensitic transformation in which metastable phases (b, g) change into the stable phase (a). For biomedical applications, the most desired is the b-phase. A very unfavourable phenomenon accompanying the martensitic transformation in a wet environment is low temperature degradation, which is an autocatalytic process accelerating negative changes in ZrO2. The aim of this review is a comprehensive study of the degradation phenomenon problems according to prosthetic treatment with a fixed prosthesis and ways to reduce it.

15

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

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2017

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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.

16

Katalityczne właściwości związków cyrkonu

Sołtysik B., Bodzek-Kochel M.

Przemysł Chemiczny

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2016

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T. 95, nr 8

1554--1558

PL

Dokonano przeglądu informacji literaturowych związanych z wykorzystaniem wybranych związków cyrkonu w katalizie ze szczególnym uwzględnieniem tlenków cyrkonu. Omówiono specyficzne właściwości tych związków, których następstwem jest ich wysoka zdolność katalityczna.

EN

A review, with 71 refs., of uses of selected Zr compds., esp. ZrO₂, in catalysis.

17

The study of the connection between the zirconia substructure and veneering porcelain in dental crowns subjected to occlusal forces

Malara P., Paluch K., Sobolewska K., Pasieka A.

Archives of Materials Science and Engineering

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2016

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Vol. 81, nr 1

5--13

EN

Purpose: The aim of the study was to examine the connection between the zirconia substructure and the porcelain in the dental crowns subjected to simulated occlusal forces. Design/methodology/approach: All-ceramic dental crowns were subjected to Vickers hardness examination, testing of compressive strength and observations of breakthroughs on the SEM. Findings: Based on the research, it was found that the compressive force at which ceramic crowns brake down, are in the range of maximum occlusal loads exerted by man. There is a mechanical connection between zirconia and porcelain. All-ceramic crowns of premolars showed the highest resistance to compressive force, while the crowns of canines are characterized by the lowest resistance to the loading force. In addition, through the research we found that ceramic crowns under static compressive loads brake down and the fracture line runs through the entire thickness of the wall, because zirconium oxide has more than twice the hardness of the porcelain. There is a difference of stresses between the materials, causing fracture of the restoration. Practical implications: The research work shows that the porcelain crowns on the substructure of zirconia (all-ceramic restoration) are a very good option of the restorative treatment in dentistry, rebuilding missing teeth. Originality/value: The article presents a study on the compressive strength of manufactured crowns, followed by a comparison to the natural forces of occlussion in human. The exact mapped tooth geometry and the appropriate veneering porcelain foundation of zirconium allows the use of prosthetic crowns in the patient's mouth without fear that porcelain will be broken.

18

Is mechanical retention for adhesive core build-up needed to restore a vital tooth with a monolithic zirconium crown? : An in vitro study

Walczak K, Rues S., Więckiewicz M., Range U., Schmitter M.

Acta of Bioengineering and Biomechanics

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2016

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Vol. 18, no. 4

117--125

EN

Purpose: To show the influence of retentive cavity, cavity wall preparation and different luting techniques on the fracture resistance of severely damaged teeth restored with adhesive core build-ups and monolithic zirconium crowns. Methods: Extracted molars were prepared with 2 mm ferrule height and divided into eleven groups (n = 8/group). In nine groups a retentive occlusal cavity with a width and depth of 1 or 2 mm was prepared. Two control groups without a retentive cavity were made. Zirconium crowns were manufactured. 48 copings were cemented with glass-ionomer cement (Ketac Cem), the others (n = 40) with adhesive resin cement (Panavia F 2.0). Artificial ageing was carried out in the following way: n = 88, thermocycling (10,000 cycles, 6° C/60° C), n = 80 chewing simulation (1,200,000 cycles, 64 N). The samples were tested for load at first damage and fracture load with non-axial force. For statistical analysis ANCOVA with post hoc, Bonferroni-adjusted t-test were used ( p ≤ 0.05). Results: No differences between the tested cements were detected. Influence of the cavity wall thickness was significant ( p = 0.001). Mostly, the samples with wall thickness of 2 mm showed better results. Both control groups (no cavity) showed results comparable to study groups with cavity. Conclusions: Retentive cavity is most likely not mandatory. However, if prepared, the cavity wall thickness is of higher importance than cavity depth. Glass-ionomer and adhesive resin cement are comparable for use with zirconia crowns.

19

Cations on Ion Chromatography by Phosphate-Coated Zirconia Stationary Phase Column

Mori M., Masuno T., Kozaki D., Nakatani N., Tanaka K., Itabashi H.

Acta Chromatographica

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2015

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Vol. 27, no. 4

767--773

EN

Ion chromatography of inorganic cations using a phosphate-coated zirconia stationary phase (PZ) was first attempted. The retentions of cations to PZ increased by elevating the column temperature and the reproducibility of the separation could improve at the higher temperature. The PZ functioned as a cation-exchanger from changes in the retention factor of cations as a function of eluent pH. Furthermore, the Gibbs free energies of cations were estimated from enthalpy and entropy using the retention factors of cations as a function of the column temperature. The reaction was based on the endothermic reaction.

20

Microstructure and mechanical properties of porous Ti-6Al-4V composites with bioceramics fabriced by spark plasma sintering

Dudek A., Klimas M.

Composites Theory and Practice

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2014

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R. 14, nr 1

23--28

EN

Substantial progress in the field of materials used for medicine has be observed in recent years, driven by the higher demand for these types of materials. Promising prospects are offered by composite materials that allow for unlimited modelling of the properties in materials used for specific medical applications. The focus of the investigations presented in this paper is placed on metallic-ceramic composites based on a titanium alloy matrix (Ti-6Al-4V) with a 20 wt.% addition of aluminium oxide (Al2O3), hydroxyapatite ceramics (Ca10(PO4)6(OH)2) and YSZ (zirconia stabilized with 8 wt.% yttria Y2O3) obtained using the spark plasma sintering method. The specimens were compressed at 35 MPa and sintered in a shielding gas (argon) medium at the temperature of 1000°C in an SPS HP 5 apparatus manufactured by FCT for 25 min. The obtained composites were subjected to microstructural analysis using an Axiovert light microscope and X-ray quality analysis using a D8 DISCOVER Bruker diffractometer. Hydrostatic weighing in deionized water according to the PN-EN ISO 2738:2001 standard was also used to evaluate the density (apparent and relative), porosity (open and total) and water absorption capacity. The topology of the surface of the metallic-ceramic composites was determined using a Hommel T1000 profilometer. The mechanical properties (microhardness) were measured using a semi-automatic microhardness tester (FM-7, FutureTech) with a Vickers indenter at a load of 100 G. The resistance to wear was evaluated by means of a ball wear testing stand. In this study, Ti6Al4V/HAp(ZrO2, Al2O3) composites were prepared using spark plasma sintering (SPS) to obtain highly compact composites. The aim of the study was to evaluate the ability of spark plasma sintering to obtain metallic-ceramic composites based on titanium alloy with an addition of inert ceramics and bioactive ceramics for medical applications.

PL

W ostatnim czasie można zauważyć ogromny postęp w dziedzinie materiałów dla medycyny, niejako wymuszony zwiększonym zapotrzebowaniem na tego typu materiały. Ogromną nadzieję upatruje się w materiałach kompozytowych pozwalających na swobodne modelowanie właściwości elementów predestynowanych do konkretnych zastosowań medycznych. Przedmiotem badań przedstawionych w niniejszym artykule są wytwarzane metodą iskrowego spiekania plazmowego (SPS - spark plasma sintering) kompozyty metaliczno-ceramiczne na osnowie stopu tytanu Ti-6Al-4V z 20% mas. dodatkiem tlenku aluminium (Al2O3), ceramiki hydroksyapatytowej (Ca10(PO4)6(OH)2) oraz ceramiki cyrkonowej YSZ (tlenek cyrkonu modyfikowany 8% mas. tlenku itru Y2O3). Próbki prasowano przy ciśnieniu 35 MPa i spiekano w atmosferze gazu ochronnego (argonu) w temperaturze 1000°C w urządzeniu typu SPS HP 5 firmy FCT przez 25 min. Otrzymane kompozyty poddano analizie mikrostrukturalnej przy użyciu mikroskopu świetlnego Axiovert, rentgenowskiej analizie jakościowej na dyfraktometrze rentgenowskim D8 DISCOVER Bruker, oceniono metodą ważenia hydrostatycznego w wodzie dejonizowanej (zgodnie z normą PN-EN ISO 2738:2001) ich gęstość (pozorną i względną), porowatość (otwartą i całkowitą) oraz nasiąkliwość. Określono ponadto topografię powierzchni otrzymanych kompozytów metaliczno-ceramicznych, stosując profilometr Hommel T1000, oceniono właściwości mechaniczne (mikrotwardość) przy wykorzystaniu półautomatycznego mikrotwardościomierza Microhardness Tester FM-7 firmy FutureTech z zastosowaniem wgłębnika Vickersa przy obciążeniu 100 G, jak również ich odporność na ścieranie za pomocą kulotestera. Celem przeprowadzonych badań było określenie przydatności metody iskrowego spiekania plazmowego do wytwarzania kompozytów metaliczno-ceramicznych na bazie stopu tytanu z dodatkiem ceramiki inertnej oraz bioaktywnej do zastosowań medycznych.