scholarly journals Microstructure and Phase Composition of Yttria-Stabilized Zirconia Nanofibers Prepared by High-Temperature Calcination of Electrospun Zirconium Acetylacetonate/Yttrium Nitrate/Polyacrylonitrile Fibers

Fibers ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 82
Author(s):  
Vyacheslav V. Rodaev ◽  
Svetlana S. Razlivalova ◽  
Alexander I. Tyurin ◽  
Andrey O. Zhigachev ◽  
Yuri I. Golovin
Keyword(s):  
Fiber Diameter ◽  
Tetragonal Zirconia ◽  
Nitrogen Adsorption ◽  
Grain Structure ◽  
Yttrium Nitrate ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Calcination Temperatures ◽  
Fine Grain ◽  
First Time

For the first time, dense nanofibers of yttria-stabilized tetragonal zirconia with diameter of ca. 140 nm were prepared by calcination of electrospun zirconium acetylacetonate/yttrium nitrate/polyacrylonitrile fibers at 1100–1300 °C. Ceramic filaments were characterized by scanning electron microscopy, X-ray diffractometry, and nitrogen adsorption. With a rise in the calcination temperature from 1100 to 1300 °C, the fine-grain structure of the nanofibers transformed to coarse-grain ones with the grain size equal to the fiber diameter. It was revealed that fully tetragonal nanofibrous zirconia may be obtained at Y2O3 concentrations in the range of 2–3 mol% at all used calcination temperatures. The addition of 2–3 mol% yttria to zirconia inhibited ZrO2 grain growth, preventing nanofibers’ destruction at high calcination temperatures. Synthesized well-sintered, non-porous, yttria-stabilized tetragonal zirconia nanofibers can be considered as a promising material for composites’ reinforcement, including composites with ceramic matrix.

scholarly journals Preparation of Zirconia Nanofibers by Electrospinning and Calcination with Zirconium Acetylacetonate as Precursor

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1067 ◽  
Author(s):  
Vyacheslav V. Rodaev ◽  
Svetlana S. Razlivalova ◽  
Andrey O. Zhigachev ◽  
Vladimir M. Vasyukov ◽  
Yuri I. Golovin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heterogeneous Catalysts ◽  
Tetragonal Zirconia ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
High Specific Surface Area ◽  
X Ray ◽  
Adsorption Analysis

For the first time, zirconia nanofibers with an average diameter of about 75 nm have been fabricated by calcination of electrospun zirconium acetylacetonate/polyacrylonitrile fibers in the range of 500–1100 °C. Composite and ceramic filaments have been characterized by scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption analysis, energy-dispersive X-ray spectroscopy, and X-ray diffractometry. The stages of the transition of zirconium acetylacetonate to zirconia have been revealed. It has been found out that a rise in calcination temperature from 500 to 1100 °C induces transformation of mesoporous tetragonal zirconia nanofibers with a high specific surface area (102.3 m2/g) to non-porous monoclinic zirconia nanofibers of almost the same diameter with a low value of specific surface area (8.3 m2/g). The tetragonal zirconia nanofibers with high specific surface area prepared at 500 °C can be considered, for instance, as promising supports for heterogeneous catalysts, enhancing their activity.

Cost-Effective Grinding of Zirconia Using the Dense Vitreous Bond Silicon Carbide Wheel

2003 ◽  
Vol 125 (2) ◽  
pp. 297-303 ◽  
Author(s):  
Albert J. Shih ◽  
Ronald O. Scattergood ◽  
Adam C. Curry ◽  
Thomas M. Yonushonis ◽  
Darryl J. Gust ◽  
...  
Keyword(s):  
Monoclinic Phase ◽  
Base Material ◽  
Ground Surface ◽  
Cost Effective ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Wheel Wear ◽  
X Ray ◽  
Fine Grain ◽  
Measurement Results

Results of grinding zirconia using wheels with fine grain size SiC and dense vitreous bond are presented. Wheel wear results demonstrated that this type of SiC wheel could grind fully and partially stabilized zirconia (PSZ) very effectively. X-ray diffraction was used to analyze the percentage of monoclinic phase in the PSZ base material, ground surface, and debris. As expected, due to the stress- and temperature-induced phase transformation during grinding, the percentage of monoclinic phase on the ground surface was increased relative to the base material. However, X-ray diffraction showed no monoclinic phase in the PSZ debris. This suggests that, during grinding, the low thermal conductivity of zirconia and SiC, compared to that of diamond, facilitates heat retention in the chip and softens the work-material. This makes the efficient grinding of PSZ possible. Grinding temperature measurement results supported this hypothesis.

Preparation of TiO2/Ga2O3 Nanowires by a Sol-Gel-Solvothermal Method

2010 ◽  
Vol 663-665 ◽  
pp. 965-968
Author(s):  
Yue Hui Wang ◽  
Dong Jun Wang ◽  
Ai Jun Song ◽  
Zhi Gang Zhang ◽  
Shi Tao Song
Keyword(s):  
Electron Microscopy ◽  
Near Infrared ◽  
Solvothermal Method ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Tetrabutyl Titanate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
First Time

TiO2/Ga2O3 nanowires were successfully prepared by a sol–gel-solvothermal method using tetrabutyl titanate as precursor, alcohol as solvent, Ga2O3 as templet and dopants, alginate as dispersant. The structures, morphologies,compositions and catalytic activity of products have been characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy ( FESEM ), nitrogen adsorption test, ultraviolet-visible near-infrared spectroscopy (UV–vis–NIR ),energy dispersive X-ray (EDX) analysis and spectrophotometer. The results revealed that the as-synthesized TiO2/Ga2O3 nanowires grew along [001] direction,which is reported for the first time, and the as-prepared product had better optical activity than TiO2 nanoparticles. Finally, the nanowires have a good adsorption capacity of 128.2 m2/g tested through nitrogen adsorption.

scholarly journals On the Reconstruction Peculiarities of Sol–Gel Derived Mg2−xMx/Al1 (M = Ca, Sr, Ba) Layered Double Hydroxides

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 470 ◽  
Author(s):  
Ligita Valeikiene ◽  
Marina Roshchina ◽  
Inga Grigoraviciute-Puroniene ◽  
Vladimir Prozorovich ◽  
Aleksej Zarkov ◽  
...  
Keyword(s):  
Layered Double Hydroxides ◽  
Pore Diameter ◽  
Sol Gel ◽  
Earth Metal ◽  
Nitrogen Adsorption ◽  
Xrd Analysis ◽  
X Ray ◽  
Double Hydroxides ◽  
Synthesized Materials ◽  
First Time

In this study, the reconstruction peculiarities of sol–gel derived Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides were investigated. The mixed metal oxides (MMO) were synthesized by two different routes. Firstly, the MMO were obtained directly by heating Mg(M)–Al–O precursor gels at 650 °C, 800 °C, and 950 °C. These MMO were reconstructed to the Mg2−xMx/Al1 (M = Ca, Sr, Ba) layered double hydroxides (LDHs) in water at 50 °C for 6 h (pH 10). Secondly, in this study, the MMO were also obtained by heating reconstructed LDHs at the same temperatures. The synthesized materials were characterized using X-ray powder diffraction (XRD) analysis and scanning electron microscopy (SEM). Nitrogen adsorption by the Brunauer, Emmett, and Teller (BET) and Barrett, Joyner, and Halenda (BJH) methods were used to determine the surface area and pore diameter of differently synthesized alkaline earth metal substituted MMO compounds. It was demonstrated for the first time that the microstructure of reconstructed MMO from sol–gel derived LDHs showed a “memory effect”.

The Effects of Composition and Sintering Conditions on Zirconia Toughened Alumina (ZTA) Nanocomposites

2010 ◽  
Vol 93-94 ◽  
pp. 695-698 ◽  
Author(s):  
H. Esfahani ◽  
Ali Nemati ◽  
E. Salahi
Keyword(s):  
Tetragonal Zirconia ◽  
Al2o3 Nanoparticles ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Constant Composition ◽  
X Ray ◽  
Different Temperatures ◽  
Lattice Network ◽  
Diffraction Patterns ◽  
Zirconia Toughened Alumina

Zirconia Toughened Alumina (ZTA) Nanocomposites were prepared using Nano sized Zirconia (ZrO2) powders doped with 3% mol of yttria (Y2O3) nanopowders. Diffusion of α-alumina (Al2O3) nanoparticles as well as yttria into the Zirconia lattice network drives monoclinic – tetragonal martensitic transformation. Zirconia toughened alumina (ZTA) composites containing different amount of partially stabilized Zirconia (PSZ) 5, 10, 15 and 20% mol, were prepared via wet mixing and axial pressing. After sintering at different temperatures,1450, 1550 and 1650 °C, phase change in the samples were monitored. X-ray diffraction patterns showed that at constant composition, tetragonal zirconia was increased by temperature increasing due to intensification of diffuse coefficient of alumina and yttria in the system. At constant temperature, remained monoclinic zirconia was increased with Zirconia content increasing.

Bioactive Grain Refined Magnesium by Friction Stir Processing

2012 ◽  
Vol 710 ◽  
pp. 264-269 ◽  
Author(s):  
B. Ratna Sunil ◽  
T.S. Sampath Kumar ◽  
Chakkingal Uday
Keyword(s):  
Grain Refinement ◽  
Friction Stir Processing ◽  
Grain Structure ◽  
Nugget Zone ◽  
Near Surface ◽  
X Ray ◽  
Friction Stir ◽  
Promising Tool ◽  
Fine Grain ◽  
Angle Measurements

Magnesium and its alloys are promising candidates for temporary implant applications due to their combination of mechanical properties, biocompatibility and biodegradation. But higher degradation rate restricts their wider applications. Recently friction stir processing (FSP) has emerged as a promising tool to attain near surface fine grain structure in materials. In the present work commercial purity magnesium was processed by FSP to obtain fine grain structure and the effect of the grain refinement on the bioactivity was investigated. The microstructural observations were carried out at different locations of the processed regions, from an original grain size of 1500μm, grain refinement was achieved to a level of 6.2μm at the nugget zone. Microhardness was measured across the processed regions and improvement was observed at the nugget zone. Contact angle measurements were carried out to estimate the wettability of the material and the measurements indicate increased wettability due to the increased surface energy induced by grain refinement. For studying the bioactivity the FSPed samples were immersed in simulated body fluids (SBF 5X) for different intervals of time. The phases formed on the samples were investigated by X-ray diffraction (XRD) method, scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. The phases on the samples after 72hr of immersion were confirmed as magnesium hydroxide, hydroxyapatite and magnesium phosphate by XRD. Controlled degradation due to formation of these phases was observed. FSPed samples have more deposition of Ca/P than non FSP samples which implies better control over the degradation. Hence grain refinement by FSP can be a simple technique to control the degradation of magnesium for temporary implant applications.

Influence of Zirconium Doped Titanium Oxide towards Photocatalytic Activity of Paraquat

2015 ◽  
Vol 1107 ◽  
pp. 377-382 ◽  
Author(s):  
Nur Afiqah Badli ◽  
Rusmidah Ali ◽  
Leny Yuliati
Keyword(s):  
Photocatalytic Activity ◽  
Working Condition ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Treatment Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Adsorption Analysis ◽  
Scanning Electron

The heterogeneous photocatalyst based on titanium dioxide has been widely investigated as an attractive treatment method for water pollution. Herbicide like paraquat dichloride is one of the toxic organic pollutants which is harmful to human and animal and is still being used in agricultural sectors. TiO2doped with zirconium element has been proven to enhance the photocatalytic activity of TiO2from the previous study. Therefore in this study, photodegradation of paraquat dichloride (1,1-dimethyl-4,4’-bipyridylium dichloride) under UV irradiation was studied using TiO2and Zr doped TiO2prepared via modified sol gel method as photocatalysts. The photocatalytic activity was increased in the presence of zirconium as dopant compared to TiO2. Various calcination temperatures range from 450°C to 1000°C and dopant ratio (10:90, 20:80 and 30:70) were applied to optimize the working condition. Significant enhancement was obtained using Zr doped TiO2(20:80) calcined at 750°C which gave 79.63% degradation of paraquat compared to TiO2calcined at 450°C and 750°C which were 22.31% and 11.57%. X-ray diffraction (XRD) diffratogram of Zr doped TiO2photocatalyst showed a mixture of anatase/rutile TiO2crystalline structures at 750°C. Nanosized photocatalyst with spherical morphology was observed by Field Emission Scanning Electron Microscopy (FESEM). The surface area measured by nitrogen adsorption analysis showed an increment from 8.43m2/g to 46.35m2/g compared to undoped catalyst calcined at 450°C.

Microstructure and mechanical properties of synthetic opal: A chemically bonded ceramic

1986 ◽  
Vol 1 (5) ◽  
pp. 667-674 ◽  
Author(s):  
Thomas C. Simonton ◽  
Rustum Roy ◽  
Sridhar Komarneni ◽  
Else Breval
Keyword(s):  
Room Temperature ◽  
Thermal Analyses ◽  
Tetragonal Zirconia ◽  
Synthetic Opal ◽  
X Ray ◽  
Optical Scanning ◽  
Thermally Activated ◽  
Mean Size ◽  
Microscopy Techniques ◽  
First Time

Among chemically bonded ceramics (i.e., those not utilizing thermally activated diffusion for bonding) the French synthetic opal gilsonite provides an excellent existence theorem. By using optical, scanning, and electron microscopy techniques and x-ray, chemical, and differential thermal analyses, it is shown for the first time that the synthetic opal is composed of two separate phases: noncrystalline silica and crystalline (tetragonal) zirconia balls. The zirconia balls with sizes ranging from 7-50 nm appear to be present in an extraordinary regular “lattice” in the void spaces of the silica “balls” of mean size 200 nm. A comparison of the fracture toughness, Kic, data for the gilsonite and natural opal shows that the former is significantly tougher than the latter. The KIC values for gilsonite fall between those of the Corning 0337 Glass Ceramic and Wesgo Al-500 alumina, showing that surprisingly tough ceramics can be made near room temperature by resorting to chemical bonding.

Synthesis and characterization of partially and fully stabilized zirconia fibers made from an inorganic precursor

2001 ◽  
Vol 16 (8) ◽  
pp. 2384-2390 ◽  
Author(s):  
A. Hartridge ◽  
M. D. Taylor ◽  
A. K. Bhattacharya
Keyword(s):  
Single Phase ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
High Quality ◽  
Creep Properties ◽  
X Ray ◽  
Cubic Structure ◽  
Sol Precursor

Continuous high-quality fibers of yttria-doped zirconia with 4 and 8 mol% yttria were blow spun using an inorganic sol precursor. The fibers were heated and analyzed using scanning electron microscopy, x-ray diffraction, differential thermal/thermogravimetric analysis, and surface area/porosity by nitrogen adsorption. The fibers were of a single-phase cubic structure after crystallization at 529 °C and typically 3.3–5.5 or 7.5–11.5 μm in diameter depending on the composition. Samples of fibers were heated to various temperatures and their friability index and creep properties analyzed using the bend stress relaxation technique and compared to other fibers of similar composition prepared by different solution techniques and commercially available fibers.

scholarly journals Synthesis of stabilized zirconia without dopants

Cerâmica ◽  
2008 ◽  
Vol 54 (330) ◽  
pp. 253-258 ◽  
Author(s):  
R. C. Pessoa ◽  
M. Cerqueira ◽  
R. S. Nasar ◽  
I. V. P. Yoshida
Keyword(s):  
Tetragonal Zirconia ◽  
Monoclinic Zirconia ◽  
X Ray Diffraction ◽  
Small Particles ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Pechini’S Method ◽  
Diffusion Interface ◽  
Complex Polymer ◽  
Kinetics Of

ZrO2-SiO2 powders were synthesized through Pechini's method starting with D4Vi, PMS and zirconium citrate. The complex polymer was decomposed to form different phases at high temperatures. During the resin decomposition, the phase transformation from monoclinic to tetragonal zirconia was detected by thermal analysis. The crystallization and the diffusion process of Si and Zr were analyzed by X-ray diffraction, XRD, scanning electron microscopy and microanalysis by EDS. Tetragonal zirconia at 1000 ºC, monoclinic zirconia at 1200 ºC and monoclinic zirconia with cristobalite silica from 1300 º to 1400 ºC were formed. From 1000 ºC to 1300 ºC a diffuse amorphous band was related to the silica phase. The mapping of Kα line of Zr and Si showed low diffusion of Si into the ZrO2 structure. The kinetics of crystallization formed macroparticles of silica and small particles of zirconia. A diffusion interface between SiO2 and ZrO2 to form ZrSiO4 phase was not observed, confirmed by XRD.

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