ZrO2 Content Research Articles

Mechanical properties of alumina/zirconia composites

Fracture toughness, bending strength, Young's modulus, hardness and subcritical crack growth were determined for six different alumina/zirconia composites. The bending strength was modelled using Weibull distribution. The fracture toughness, bending strength and resistance to subcritical crack growth increase as a function of ZrO2 content (stabilized with 3 mol% Y2O3). The authors claim that a threshold stress in a three-parameter Weibull distribution may correspond to a threshold stress intensity factor in which the subcritical crack growth is negligible.

Photocatalytic properties of zirconium oxide\u2013zinc oxide nanoparticles synthesised using microwave irradiation

ZrO2–ZnO nanoparticles with different mass concentrations of ZrO2 (1%, 5%, 10%, 20%) were prepared using a two-stage precipitation method with microwave irradiation. The ZrO2–ZnO with 10% of ZrO2 had the highest photocatalytic activity. The obtained material was characterised using XRD, which confirmed a high crystal structure in the synthesised material, and transmission electron microscopy (TEM) analysis, which depicted that micro and nano needle-shaped particles had been obtained and that irregularly shaped nanoparticles were present on the surface of those particles. TEM–EDX analysis confirmed the presence of both ZnO and ZrO2 in the product. FT-IR analyses showed that the positions of peaks related to Zn–O and Zr–O absorption bands did not change in ZrO2–ZnO NPs. The initial concentration of Methylene Blue (MB), the pH of the solution, and the mass of the photocatalyst were investigated to determine the photocatalytic efficiency of the material and the degree of removal of the MB. The highest efficiency (97%) was obtained in the following conditions: 30 mg/dm3 of the MB solution, pH 9 and 70 mg ZrO2–ZnO after 30 min of reaction time under UV irradiation.

Effects of nano ZrO2 content on the comprehensive properties of BN-SiC composites

Hot-pressed BN-SiC composites applied for the steel casting application were enhanced using nano Al2O3 and ZrO2 additives. The influences of nano ZrO2 content on the mechanical properties, thermal shock resistance, oxidation resistance, and steel corrosion resistance of BN-SiC composites were investigated. The results showed that the collaborative addition of nano ZrO2 and Al2O3 dominated the densification behavior due to the enhanced solid diffusion and pore filling effects. the improved densification and induced microstructure evelopment contributed to enhanced mechanical properties and thermal shock resistance. Consequently, the flexural strength and fracture toughness of 15 wt% nano ZrO2 containing specimens reached to 334.6 ± 0.1 MPa and 4.60 ± 0.13 MPa m1/2, respectively. Furthermore, no catastrophic fracture was observed during thermal shock tests even under a temperature difference at 1200 °C. In addition, the prepared composites exhibit excellent steel corrosion resistance at 1600 °C, attributing to the much finer grain size and quick formation of protective ZrO2 layer at the interface.

Properties of zirconia-containing glass-ionomer cement

Abstract Glass-ionomer cements (GICs) are used as restorative dental materials due to their capacity to chemically adhere to enamel and dentin, low thermal expansion coefficient, and compatibility with dental structures. However, these materials have low resistance to wear and fracture. In this work, zirconia-reinforced GICs were prepared to evaluate the influence of particle size as well as ZrO2 content on their properties. All evaluated composites presented compressive strength values above the pure GIC strength. The highest compressive strength values were obtained with the addition of 8.5 wt% ZrO2. The average roughness obtained was not significantly changed compared to commercial GIC and the lowest value was for the composite with 10 wt% ZrO2 (50 mesh). In the microhardness test, the highest values were obtained with the addition of 8.5 wt% of ZrO2. Therefore, the results indicated that the addition of ZrO2 to GIC is an effective alternative to improve the quality of dental restorations.

Study of Crystallization Kinetics of Amorphous Zirconia in Fe<sub>2</sub>O<sub>3</sub> Matrix by Kissinger Method

The composite materials Fe2O3-ZrO2 with different content of zirconium oxide have been obtained by thermochemical synthesis. The process of crystallization of zirconium dioxide and the effect of the amount of zirconium dioxide on the phase transformation have been studied by DTA and microscopy. The activation energy of the crystallization process was calculated by the Kissinger method to be in average 170 KJ/mol. It is shown that an increase of the ZrO2 content leads to an increase of temperature of crystallization.

Preparation and Characterization of Gel Polymer Electrolyte Based on PAN- NH4CF3SO4 and Nano ZrO2 Filler –Application as an Electrochemical cell

In the present investigation, the Nano Composite Gel Polymer Electrolyte (NCGPEs) based on nano fillers ZrO2, Polyacrylonitrile (PAN), and Ammonium Triflate (NH4CF3SO4) doped at various wt% ratios prepared with the help of solution cast technique. The better amorphous nature observed for the 70PAN:30NH4CF3SO4 composition with addition of 1-4 wt% of ZrO2 nano fillers and structural, complexation studies of NCGPEs were confirmed by XRD technique. The micro structural studies and particle size can be revealed by SEM technique. DC Conductivity studies reveal the ionic conductivity performance on effect of temperature and composition wt% of nano powder. The ionic conductivity studies observed for 70PAN:30NH4CF3SO4 with nano powder ZrO2 concentration ranging from 1-4 wt%. The sample containing 3wt% of ZrO2 exhibits the highest conductivity order of 4.20x10-4 S cm-1 at room temperature (303K) and 4.65x 10-3 S cm-1 at 373K. The cell parameters like Open Circuit Voltage, Short Circuit Current, energy density and power density were perfectly determined which were useful to explain electrochemical cell behaviour.

Mixed valence effect of Se6+ and Zr4+ on structural, thermal, physical, and optical properties of B2O3–Bi2O3–SeO2–ZrO2 glasses

Conventional melt quench technique has been used to synthesize the highly polarizable glass system with composition (70B2O3–30Bi2O3), (70B2O3–25Bi2O3–5SeO2) and (70B2O3–23Bi2O3–5SeO2–2ZrO2)in (wt%)abbreviated as BB, BBS and BBSZ respectively. Structural, thermal, physical and optical properties of the modified glass system have been studiedusing XRD, DSC, FTIR, Raman and UV–Vis Spectroscopy. XRD have been performed to confirm the amorphous nature of samples. The calculated OPD values and DSC analysis confirmed decrease in Tg on the addition of SeO2 and ZrO2 content. FTIR and Raman data revealed the existence of characteristic bands of [BiO3], [BiO6], [BO3], [BO4], [SeO42−], [SeO32−] units and Zr–O–Zr linkages. The effect of ZrO2 on the structural stability has been observed using density and molar volume. Adecrease in band gap resulting from the increase in NBO's has been confirmed by UV–Vis spectroscopy as well as from physical parameters like metallization criterion and urbach energy. An increase in refractive index is observed on the addition of SeO2. The parameters electronic polarizability, optical basicity and electronegativity confirms the ionic character of the studied glass samples.

High temperature interaction of volcanic ashes with 7YSZ TBC's produced by APS: Infiltration behavior and phase stability

High-temperature infiltration behavior and phase stability of yttria-stabilized zirconia (7YSZ) thermal barrier coatings (TBC) produced by atmospheric plasma spray interacting with volcanic ashes (VAs) are presented here. Three VAs from the Colima, Popocatepetl, and Eyjafjallajökull volcanoes have been used in this work. Previous to infiltration experiments, physicochemical characterization of the VAs was carried out including thermal analyses by DSC, structural studies by XRD, and ICP chemical composition measurements. TBCs' infiltration tests were carried out at 1250 °C for different times. Results showed that infiltration depth as a function of time behaves in a non-linear way. Mainly two important infiltration behaviors were identified corresponding to high- and slow-speed infiltration regimes. Higher infiltration kinetics was detected for VAs with lower SiO2 content. The extent of chemical degradation of the 7YSZ is directly related to the silica content. For greater SiO2 values, a higher content of monoclinic ZrO2 was observed leading to maximum values at intermediate annealing times between 2 and 5 h. This behavior can be correlated with the high-speed tetragonal to monoclinic ZrO2 transformation at short times (between 2 and 5 h) until a maximum monoclinic content is reached. After that, the reaction follows by the interplay of ZrSiO4 formation at the expense of previously formed m-ZrO2 together with the incorporation of Y and Zr to the glass melt.

Fast-setting and anti-washout tricalcium silicate/disodium hydrogen phosphate composite cement for dental application

Although Mineral trioxide aggregate (MTA) has been widely used in endodontic treatments and gained great clinical success, development of fast-setting tricalcium silicate (TCS)-based cements with good anti-washout performance remains a huge challenge. Hence, this study was aimed at engineering a novel TCS-based endodontic material to meet abovementioned requirements via introduction of disodium hydrogen phosphate (Na2HPO4) as the hydration accelerator. The setting time, flowability, mechanical strength and anti-washout property of the composite cements were evaluated. Furthermore, bioinert ZrO2 was used as radiopacifier and the effects of ZrO2 content on the radiopacity, physicochemical properties, apatite-formation ability, pH, antibacterial activity, cement-dentin interface and cell cytocompatibility of radiopaque composite cements with an optimal component were also investigated. The results showed that the setting time of cement pastes notably shortened from 169 to 33 min with adjusting the amount of Na2HPO4 from 0 to 30 wt%, whereas flowability and compressive strength of cements exhibited a decreasing trend. Meanwhile, cement pastes displayed good anti-washout performance because of acceleratory effect of Na2HPO4 on hydration process of TCS and formation of additional binding phase. Furthermore, the radiopacity of hybrid cements obviously enhanced with the addition of ZrO2 while a little increase in setting time was observed, and washout resistance of composite pastes was slightly reduced with the increase in ZrO2 amount. The radiopaque composite pastes could induce apatite deposition on their surfaces and showed good marginal adaptation at cement-dentin interface. Additionally, the addition of ZrO2 content had no significant influences on alkaline formation ability, antibacterial activity, and cell cytocompatibility of cement pastes. Our results indicated that TCS/Na2HPO4/ZrO2 cement exhibited a great potential to be used as a novel dental material and might be a promising candidate for endodontic treatments.

TiO2-ZrO2 membranes of controlled pore sizes with different Ti/Zr ratios for nanofiltration

TiO2-ZrO2 colloidal and polymeric sols were successfully prepared using the sol-gel method. The effects of aging and Ti/Zr molar ratios on TiO2-ZrO2 sols and powders were investigated. The particle size of colloidal sols was decreased with an increase in aging time, while the particle size of the polymeric sols increased. TiO2-ZrO2 polymeric sols with Ti/Zr molar ratios that varied from 10/0 to 0/10 showed an increase particle size with an increase in the Zr-content. In addition, TiO2-ZrO2 powders derived from colloidal sols had a crystalline structure even without firing. With firing at temperatures that approached 500 °C, however, TiO2-ZrO2 powders derived from polymeric sols had a structure that was more amorphous than that of pure TiO2 and ZrO2 powders, but the most amorphous structure was achieved at a Ti/Zr molar ratio of 5/5. TiO2-ZrO2 nanofiltration (NF) membranes, which were prepared by coating colloidal and polymeric sols onto α-Al2O3 porous supports, showed an average pore size and molecular weight cut-offs (MWCOs) in the NF range. Average pore size, N2 permeance, water permeability (Lp), and MWCOs of the membranes were generally decreased with an increase in ZrO2 content with an optimum addition of ZrO2 that approached an equimolar composition. TiO2-ZrO2 (9/1, 7/3, 5/5) membranes showed a relatively low MWCO and a moderate Lp, which suggested that these membranes would be good for nanofiltration.

Study on Inclusions in Almandine Garnet from Vemireddipalle Area, Krishna District, Andhra Pradesh, India

Almandine Garnet is purplish red in colour. The mineral samples are collected from Vemireddipalle area, Krishna District, Andhra Pradesh. Dataset/points are examined using EPMA. It is found that P2O5 (29.34%) and Ce2O3 (22.47%) are abundant and the major oxides support the presence of Monazite inclusion. The high concentration of ZrO2 and SiO2 helped to confirm the other inclusion as Zircon.

Coating Y2O3 nano-particles with ZrO2-additive via precipitation method for colloidal processing of highly transparent Y2O3 ceramics

In the present work, transparent Y2O3 ceramics were prepared via colloidal processing method using ZrO2-coated nano-sized Y2O3 powders. The chemical precipitation method was adopted for the coating of Y2O3 raw powder. The evolution of the coated-ZrO2 layer upon calcination was studied. The rheological behaviors of the slurries of Y2O3 powders coated with different content of ZrO2-additive were investigated. The pHIEP of ZrO2-coated Y2O3 powders shows intermediate values between that of raw Y2O3 and ZrO2 powders. As the ZrO2-coating concentration increased from 0 to 5.0 at%, the magnitude of the negative zeta potential at pH > pHIEP shows a general trend of increment, whereas it decreased at pH < pHIEP. The viscosity decreases pronouncedly with the increase of ZrO2 content from 0.5 at% to 3.0 at%. The suspensions with low viscosity and high stability was achieved for a solid loading of 35.0 vol% using Y2O3 powders coated with 5.0 at% ZrO2. The dispersed suspensions were consolidated by centrifugal casting method and the green bodies shown improved homogeneity. Transparent Y2O3 ceramics were fabricated by vacuum sintering at 1800 ℃ for 5 h. Transmittance at wavelength 800 nm (1.0 mm thick) reached 80.8%, close to the theoretical value of Y2O3.

Evaluations of Hot Corrosion Behavior of Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Thermal Spray Coatings with ZrO&lt;sub&gt;2&lt;/sub&gt; Reinforcements on T-91 Steel

Different coating with varying quantities of Al2O3 and ZrO2 were fabricated on the SA213 T-91 steel using plasma spray method to study hot corrosion resistance behavior. Experiment was conducted under the molten salt environment of 60% Na2SO4-40%V2O5 at a temperature of 900℃ inside a furnace for 50 cycles. Each cycle consisted of 1hr heating and 20 min cooling at room temperature. Results were examined using the visual inspection, weight change measurement, X-ray diffraction technique and Scanning Electron Microscopy/ Energy Dispersive X-Ray Spectroscopy (SEM/ EDS) analysis. Results showed that uncoated T-91 steel was more prone to hot corrosion as compared to coated steel specimens. It was noticed that ZrO2 reinforcements in Al2O3 coating matrix helped to enhance corrosion resistance of these coatings. The corrosion resistance increased with increase in ZrO2 content in coating matrix.

Characterisation and properties of Ni–W–Y2O3–ZrO2 nanocomposite coating

ABSTRACTIn this work, nickel-based composite coatings were deposited using ultrasonic electrodeposition under pulse current condition at different current densities, temperatures and concentrations of Y2O3 and/or ZrO2 dispersed in the plating solution. The morphology and electrochemical properties were investigated. The electrochemical test methods (such as chronopotentiometry, potentiodynamic polarisation and electrochemical impedance spectroscopy) were used to investigate the stability of electrode potential during deposition and the corrosion resistance of Ni-based coating reinforced using Y2O3 and ZrO2. It was demonstrated that, when the deposition current density was 1.5 A dm−2, the temperature was 60°C and the added amount of Y2O3 and ZrO2 nanoparticles was 10 g L−1 each, the coating was compact, stable and free of cracks. The results of electrochemical tests showed that, under the optimal deposition parameters, the deposition process was stable, while the corrosion current density decreased by an order of magnitude compared to Ni–W alloy.

Enhanced sulfur‐resistant methanation performance over MoO3–ZrO2 catalyst prepared by solution combustion method

Sulfur‐resistant methanation of syngas was studied over MoO3–ZrO2 catalysts at 400°C. The MoO3–ZrO2 solid‐solution catalysts were prepared using the solution combustion method by varying MoO3 content and temperature. The 15MoO3–ZrO2 catalyst achieved the highest methanation performance with CO conversion up to 80% at 400°C. The structure of ZrO2 and dispersed MoO3 species was characterized using X‐ray diffraction and transmission electron microscopy. The energy‐dispersive spectrum of the 15MoO3–ZrO2 catalyst showed that the solution combustion method gave well‐dispersed MoO3 particles on the surface of ZrO2. The structure of the catalysts depends on the Mo surface density. It was observed that in the 15MoO3–ZrO2 catalyst the Mo surface density of 4.2 Mo atoms nm−2 approaches the theoretical monolayer capacity of 5 Mo atoms nm−2. The addition of a small amount of MoO3 to ZrO2 led to higher tetragonal content of ZrO2 along with a reduction of particle size. This leads to an efficient catalyst for the low‐temperature CO methanation process.

Effect of Zirconium Oxide Nano-Fillers Addition on Transverse Strength And Impact Strength of Heat-Polymerized Acrylic Resin, An in Vitro Study

Aim: The purpose of this study was to evaluate the effect of Zirconium oxide (ZrO2) nanofillers powder with different concentration (1.5%, 3%, 5% and 7%) on the transverse strength and impact strength of heat-polymerized acrylic resin. Materials and Methods: Zirconium oxide powders with different concentrations (1.5%, 3%, 5% and 7%) were incorporated into heat-cure acrylic resin (PMMA) and processed with optimal condition (2.5:1 Powder/monomer ratio, conventional packing method and water bath curing for 2 hours at 95˚C) to fabricate test specimens of PMMA of dimensions (65 x 10 x 2.5mm) for the transverse strength and (60 x 7 x 4mm) for impact strength. PMMA without additives was prepared as a test control. Two types of mechanical tests; transverse strength and impact strength were carried out on the samples. The recorded values transverse strength in (MPa) and impact strength in (J) were collected, tabulated and statistically analyzed. One way analysis of variance (ANOVA) and Tukey’s tests were used for testing the significance between the means of tested groups which are statistically significant when the P value ≤ 0.05. Results: Addition of Zirconium oxide nanofillers to PMMA significantly increased the transverse strength and impact strength Conclusion: Zirconium oxide nanofillers added to PMMA has a potential as a reliable denture base material with increased transverse strength and impact strength. According to the results of the present study, the best mechanical properties were achieved by adding 7%wt ZrO2 concentration.

Electrical and magnetic properties of ZrO2-doped lithium-titanium-zinc ferrite ceramics

Abstract This report documents the effect of 0–3 wt% ZrO2 additive on the electrical and magnetic properties of LiTiZn ferrite. Ferrite powder of Li0.65Fe1.6Ti0.5Zn0.2Mn0.05O4 composition was synthesised at 900 °C for 4 h in air. Ferrite ceramics doped with ZrO2 were sintered at 1010 °C for 2 h in air. A spreading resistance analysis showed that LiTiZn ferrites exhibited nonuniform distribution of depth DC resistivity, which varied in the range of (0.25–2.3) × 109 Ω⋅cm depending on the amount of additive. Zirconia also affected the magnetic properties of ferrite so that the magnetisation increased and the initial permeability decreased as the ZrO2 content increased. In addition, the Curie temperature varied. The permeability spectra measured in the frequency range from 10 MHz to 18 GHz changed depending on the zirconia content.

Synthesis of BaCe0.9-xZrxY0.1O3-δ nanopowders and the study of proton conductors fabricated on their basis by low-temperature spark plasma sintering

Using a citrate-nitrate process, BaCe0.9-xZrxY0.1O3-δ (x = 0, 0.5, 0.6, 0.7 and 0.8) nanopowders were synthesized, on the basis of which proton-conducting solid electrolytes (average size of coherent scattering region (CSR) - 15–53 nm) were obtained by spark plasma sintering (SPS) at a low temperature (900°С). The dependence of phase composition, microstructure and electrophysical properties of the obtained samples on ZrO2 content and consolidation conditions was established. It was found that the BaCe0.4Zr0,5Y0.1O3-δ solid solution had the highest electrical conductivity among zirconium-containing ceramic materials in the studied concentration range. It was shown that SPS is a promising method for obtaining solid electrolytes for proton-conducting solid oxide fuel cells (PCFC) at lower temperatures (by 400–500°С), compared to traditionally-used temperature conditions (1400–1800 °C).

Corrosion of SiO2–B2O3–Al2O3–CaF2-R2O (R=Na and K) enamels with different content of ZrO2 in H2SO4 and NaOH solutions

Abstract Corrosion of three SiO2–B2O3–Al2O3–CaF2-R2O (R = Na and K) based enamels with different ZrO2 contents in H2SO4 and NaOH solutions was studied. The addition of ZrO2 reduced acid resistance of enamels. Especially for enamel with 5 wt% zirconia, the weight loss reached 4.04 mg/cm2 after 30-day corrosion. On the contrary, substituting ZrO2 for SiO2 greatly improved the alkali resistance of enamel, since the weight loss of enamel with ZrO2 was only 0.3 mg/cm2 after 20-h corrosion, which decreased to less than one third of that of enamel without ZrO2. Corrosion mechanism was comparatively discussed in these two solutions.

Investigating the Mechanical Properties of ZrO2-Impregnated PMMA Nanocomposite for Denture-Based Applications.

Acrylic resin PMMA (poly-methyl methacrylate) is used in the manufacture of denture bases but its mechanical properties can be deficient in this role. This study investigated the mechanical properties (flexural strength, fracture toughness, impact strength, and hardness) and fracture behavior of a commercial, high impact (HI), heat-cured denture base acrylic resin impregnated with different concentrations of yttria-stabilized zirconia (ZrO2) nanoparticles. Six groups were prepared having different wt% concentrations of ZrO2 nanoparticles: 0% (control), 1.5%, 3%, 5%, 7%, and 10%, respectively. Flexural strength and flexural modulus were measured using a three-point bending test and surface hardness was evaluated using the Vickers hardness test. Fracture toughness and impact strength were evaluated using a single edge bending test and Charpy impact instrument. The fractured surfaces of impact test specimens were also observed using a scanning electron microscope (SEM). Statistical analyses were conducted on the data obtained from the experiments. The mean flexural strength of ZrO2/PMMA nanocomposites (84 ± 6 MPa) at 3 wt% zirconia was significantly greater than that of the control group (72 ± 9 MPa) (p < 0.05). The mean flexural modulus was also significantly improved with different concentrations of zirconia when compared to the control group, with 5 wt% zirconia demonstrating the largest (23%) improvement. The mean fracture toughness increased in the group containing 5 wt% zirconia compared to the control group, but it was not significant. However, the median impact strength for all groups containing zirconia generally decreased when compared to the control group. Vickers hardness (HV) values significantly increased with an increase in ZrO2 content, with the highest values obtained at 10 wt%, at 0 day (22.9 HV0.05) in dry conditions when compared to the values obtained after immersing the specimens for seven days (18.4 HV0.05) and 45 days (16.3 HV0.05) in distilled water. Incorporation of ZrO2 nanoparticles into high impact PMMA resin significantly improved flexural strength, flexural modulus, fracture toughness and surface hardness, with an optimum concentration of 3–5 wt% zirconia. However, the impact strength of the nanocomposites decreased, apart from the 5 wt% zirconia group.