Pure Zirconium Research Articles

Osteoblastic response to biomaterials surfaces: Extracellular matrix proteomic analysis.

The cellular response to surfaces is mediated, among other factors, by the extracellular matrix (ECM). However, little is known about the ECM proteome during mineralization. Our objective was to compare the ECM composition formed by osteoblast on different materials surfaces with proteomic analysis. Three types of biomaterial surfaces (pure titanium, anodized titanium, and zirconia) were used. Osteoblasts (MC3T3 linage) cells were cultivated on the biomaterials for 7, 14, and 21 days with the osteogenic medium. For the proteomic analysis, the specimens were washed, decellularized, and the ECM was collected. The majority of the typical ECM proteins, out of a total of 24 proteins identified, was expressed and regulated equally on the three biomaterials tested. Alpha-1,4 glucan phosphorylase was found to be down-regulated on zirconia on the seventh day, while at the same time, glycogen phosphorylase brain form was up-regulated on anodized titanium, both when compared with pure titanium (ratio: 1.06 and 0.97, respectively). And after 14 days of culture, glycogen phosphorylase brain form was downregulated on zirconia when compared with pure titanium (ratio: 0.90), suggesting the influence of material surface roughness and chemical composition on energy metabolism. Proteins related to bone development like Transforming growth factor beta-3 and Fibroblast growth factor 8 were found exclusively on pure titanium on the 21st day. Altogether, our results show a possible influence of material surfaces on the composition of ECM.

SYNTHESIS OF CERIUM YTTRIUM COSTABILIZED ZIRCONIUM DI-OXIDE BY SOLGEL PROCESS

The Sol–gel route was used to synthesize Ceria– Yttria co-stabilized Zirconia (CYSZ) nanoparticles. The addition of stabilizing oxides to pure Zirconia, such as CaO, MgO, CeO2, and Y2O3, allows for the formation of multiphase materials, which are referred to as CoStabilized Zirconia. Cerium Oxide CeO2 and Yttrium Oxide Y2O3 are co-stabilized with Zirconium Oxide in this study. The creation of nanostructured coatings has been shown to boost the efficiency of TBCs by lowering thermal conductivity, increasing bonding power, and increasing thermal cycling lifetime, according to researchers. The crystallinity and stabilization of cubic crystalline phases were studied by energy dispersive X-ray spectroscopy (EDAX) at different calcination temperatures in the range of 500°C to 1200°C, and surface morphology and compositional analysis were studied by scanning electron microscopy using the sol-gel process (SEM). The research yielded interesting results, but it was discovered that when Zirconium Dioxide was synthesized using the sol-gel process, the tetragonal phase was not present; thus, other methods to obtain the tetragonal phase would be needed in the future for the application of Thermal Barrier Coating.

Effect of Raw Material Purity on Structure and Properties of Metallic Glasses

Zirconium base metallic glasses [Zr0.73(Cu0.59Ni0.41)0.27]87Al13 was fabricated by industrial zirconium with low purity and high purity zirconium according to different quality ratios in order to study the effect of raw material purity on the structure and properties of metallic glasses. The results showed that the complete metallic glasses was failed to be fabricate with low purity zirconium. And the compression process was typical brittle fracture with low compressive strength and without plastic strain. The glasses forming ability of low purity zirconium metallic glass with different purity was significantly improved after the addition of yttrium element. The compression experiments showed that the compressive strength and plasticity of metallic glasses were improved, and the microhardness was also increased. It indicates that yttrium element can eliminate the adverse effect of impurity in low purity zirconium on the glasses forming ability of the alloy and improve the structural properties of the metallic glasses.

Steam oxidation behavior of ZrO2/Cr-coated pure zirconium prepared by plasma electrolytic oxidation followed by filtered cathodic vacuum arc deposition

Plasma electrolytic oxidation (PEO) and filtered cathodic vacuum arc deposition (FCVAD) techniques were employed to fabricate a ZrO2/Cr composite coating on pure zirconium. The steam oxidation properties of bare and ZrO2/Cr-coated pure Zr were performed in water vapor environment at 900–1100 °C. Their morphologies, microstructures and phase constituents before and after steam oxidation were analyzed. Meanwhile, their composition depth profiles were measured by glow discharge optical emission spectroscopy (GDOES). It was found that the mass gain of ZrO2/Cr-coated Zr was about 22–45% of that of bare Zr after 3600 s steam oxidation at 900–1100 °C, and the PEO and FCVAD composite treatments significantly improved the steam oxidation resistance of Zr. After steam oxidation, the phosphorous element in the outer layer of PEO film from phosphate electrolyte diffused into the residual Cr layer, however, most of the phosphorous in the interior of PEO layer was remained although the phosphorus diffusion in the region was accelerated with the increase of steam temperature. The ZrO2 to Zr3O phase transformation in PEO intermediate layer occurred in high temperature steam. Furthermore, the PEO zirconia interlayer suppressed hydrogen permeation into the Zr substrate during steam oxidation at 900–1100 °C.

Novel reusable sulfate-type zirconium alginate ion-exchanger for fluoride removal

It is still a challenge to eliminate efficiently fluoride ion from groundwater, especially to design and synthesis an adsorbent possessing high adsorption capacity, recyclability and wide pH application conditions. Herein we present millimeter-sized sulfate-type zirconium alginate hydrogel beads with 3D network structure (AHB@Zr-SO42−) that exhibited a maximum adsorption capacity of 101.3 mg/g with wide pH applicability (pH 3−9). This material have ~2.5 times higher adsorption capacity than that of pure zirconium alginate hydrogel beads (AHB@Zr) and it was ascribed to ion exchange between SO42− and F− on the surface of AHB@Zr-SO42−, which was verified via ion chromatography measurement coupled with X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared Spectrometer (FTIR Spectrometer) analysis. Density functional theory (DFT) calculations indicated that the ion exchange process between SO42− and F− in AHB@Zr-SO42− was energetically favorable than OH− and F− in AHB@Zr. In addition, 310 bed volumes (BV) of effluent was realized via column adsorption of groundwater containing fluoride on AHB@Zr-SO42− and indicated that it is a promising candidate for mitigating the problem of fluoride-containing groundwater.

X-ray fluorescence determination of small quantities of hafnium in nuclear pure zirconium materials

An important chemical impurity in the composition of zirconium materials for nuclear power engineering is hafnium, the content of which should not exceed 0.05 and 0.01% for domestic and foreign alloy grades, respectively. Hafnium, being an analogue of zirconium in its chemical properties, is difficult to be analyzed using classical methods of analytical chemistry. Among the physical methods, the X-ray fluorescence method is the most expressive, which is important in conditions of continuous production. The method of X-ray fluorescence for measuring the content of hafnium in zirconium-containing material has been tested on the example of potassium fluorozirconate, a precursor for obtaining alloys. With various combinations of crystal analyzers, detectors, and collimators of the wave-dispersive spectrometer, the ratios of the intensities of the analytical lines of Hf and Zr in the second order of reflection were refined, and the degree of decrease in the fluorescence intensity of those lines was determined. The X-ray fluorescence spectra of hafnium lines in potassium fluorozirconate at the content characteristic of nuclear-pure zirconium are studied. The possibility of recording the intensity of the Hf analytical lines and methods of eliminating the interference from the Zr lines in the second order of reflection are considered. The metrological characteristics are calculated for Hf analytical lines. It is shown that the smallest error and the lowest detection limit (0.001%) is provided when using the HfLβ1 line at certain settings of the wave-dispersive spectrometer, including the X-ray tube operation mode, a combination of a crystal analyzer, a detector and a collimator, as well as the amplitude discriminator settings. The method of accounting for the background is recommended. The proposed method of hafnium determination is applicable to the materials with a constant content of zirconium.

Incommensurate modulated structure in zirconium under three-point bending deformation

Three-point bending tests (bending angle ~46°) were carried out on pure zirconium. The characteristic of microstructure after deformation was studied using transmission electron microscopy (TEM). Results showed that two types of face-centered cubic (FCC) phases were induced and a unique incommensurate modulated structure (IMS) was observed between these two FCC lamellae. In addition, the modulation wave vector q = −0.129b* + 0.318c*. Most importantly, the IMS was induced by periodic deformation fluctuations during hexagonal close-packed (HCP) to FCC phase transformation by the bending deformation.

Hf1−xZrxO2 and HfO2/ZrO2 gate dielectrics with extremely low density of interfacial defects using low temperature atomic layer deposition on GaN and InP

Achieving a negative capacitance field effect transistor with a subthreshold swing beyond the Boltzmann limit requires a “defect-free” dielectric-semiconductor interface. We grew alloyed (Hf1−xZrxO2) and stacked (HfO2/ZrO2) gate dielectrics on GaN and InP substrates using low temperature plasma enhanced atomic layer deposition. In situ ellipsometry data show that alloying hafnia with zirconia reduces the refractive index and widens the bandgap. The stacked and alloyed structures reveal very low capacitance-voltage hysteresis of 35 and 45 mV, respectively, on GaN. The density of interfacial traps as low as 1.12 × 1010 cm−2 eV−1 was achieved on GaN mainly due to the combination of very low dielectric growth temperature (100 °C) and high postfabrication heat treatment temperature (510 °C). The conduction and valence band offsets of the alloyed gate dielectrics on InP were measured and compared to pure zirconia using a combination of x-ray photoelectron spectroscopy and ellipsometry. The alloyed structures show a wider bandgap, larger conduction band offset, and smaller valence band offset compared to pure zirconia. This was attributed to the increase in the valence band width with hafnia addition, which reduces the alloyed gate dielectric’s valence band offset. We resolved the band structure alignement to be type I with band offsets of 3.53 eV for electrons and 1.03 eV for holes in Hf0.25Zr0.75O2/InP heterojunctions. The results allow for a clear and detailed picture of two distinct growth procedure that affect the interfacial defect concentration.

Ferroelectric properties of pure ZrO2 thin films by chemical solution deposition

Ferroelectricity in pure zirconia (ZrO2) thin films, manufactured on Si (100) substrates via the chemical solution deposition method using all-inorganic aqueous salt precursor, has been demonstrated for the first time. The influence of thickness on the crystalline structure and ferroelectric properties of the thin films were measured and showed that they were strongly affected by the film thickness. The structural data indicated that as the film thickness increased from 30 nm to 50 nm, the m-phase fraction increased, and a phase transition from orthorhombic to cubic and then tetragonal occurred near the main diffraction peak of 30.7°. The lowest m-phase fraction of 15.4% was obtained in the pure ZrO2 film with a thickness of 30 nm, and after 103 field cycling, it exhibited the highest relative permittivity of 39.6 as well as the highest residual polarization of 8.5 μC/cm2.

Thermal Conductivity and Oxygen Tracer Diffusion of Yttria Stabilized Zirconia by Molecular Dynamics

One of the most technologically beneficial engineering ceramics is yttria stabilized zirconia (YSZ). As a result, research interest about YSZ has been intensive for many years. In this study, the lattice thermal conductivity and oxygen diffusion coefficient of YSZ are investigated at different temperatures (from 700 K to 1300 K) and zero pressure with the Green-Kubo formalism. We find that the lattice thermal conductivity decreases as the temperature increases, particularly at low temperatures and it shows a slightly temperature independence at high temperatures. The results demonstrate that the YSZ has quite a low thermal conductivity compared with pure zirconia. We also show that the oxygen tracer diffusion coefficient, as calculated from the mean square displacements, has an activation energy of 0.85eV.

Huge local elastic strains in bulk nanostructured pure zirconia materials

From the liquid state to room temperature, two successive solid-state phase transitions occur in pure zirconia. It is well-known that the last one (tetragonal to monoclinic) is martensitic and induces large volume variations and shear strains. Elastic and inelastic behaviors of zirconia-based materials are strongly influenced by this transition and the associated strain fields that it induces. Knowledge of strain and stress at the crystal scale is thus a crucial point. Using fully dense pure zirconia polycrystals obtained by a fuse casting process, we have determined at a sub-micrometric scale, by X-ray Laue microdiffraction, the strains map at room temperature in as-cast specimens and after a post elaboration high temperature thermal treatment. We observed that the fluctuation of deviatoric elastic strain is huge, the standard deviation of normal component being in the range of 1–2%. The heat treatment tends to even further increase this range of fluctuation, despite the development of a multiscale crack network formed during the cooling. Correspondingly, the associated stress level is also huge. It lies in the 5 GPa range with stress gradient amounting 1 GPa μm−1.

Instantaneous phenomena during the pulsed fiber laser welding of pure zirconium in a hyperbaric environment

The instantaneous evolutions of the molten pool and plasmas during the pulse fiber laser welding of pure zirconium (Zr) under different high pressure environment were explored. Furthermore, the mechanism and influence law of the increase of the pressure on the weld penetration of pure Zr were analyzed. The result indicated that the weld penetration of pure Zr significantly reduced with the ambient pressure’s growth. That is because of it could lead to the strengthening of the shielding effect of plasmas generated during laser welding on laser energy and improve the evaporating temperature required to produce the recoil pressure. The research result can enrich the theory on laser process under hyperbaric conditions and is favorable for the development of the laser manufacturing technology in the nuclear industry.

Microstructure characterization of gradient structured surface layer in pure zirconium

A gradient nanostructure with thickness of 150 μm at surface layer was produced on pure zirconium (Zr) by ultrasonic shot peening (USSP). The microstructure of the gradient layer was characterized by electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results indicate that multiple gradient features that consist of grain size gradient, strain gradient (low angle grain boundaries (LAGBs) gradient and geometrically necessary dislocation (GND) density gradient) and deformation twinning gradient are observed. By high resolution EBSD analysis, it is found that 101¯2<101¯1>/112¯1<1¯1¯26> twinning and dislocation slip are observed in the highly deformed surface layer. The deformation twins are parallel or intersected with each other and subdivide the coarse grains into small blocks. The movement and accumulation of dislocations gradually transform into LAGBs which finally forms finely distributed equiaxed grains. The mutual promotion between slip and twinning accelerates the process of grain refinement. The combination of twin-twin intersections and twin-LAGBs interactions ultimately leads to the formation of nano grains in pure Zr during USSP process

Modified wet chemical method synthesis of nano-ZrO2 and its application in preparing membranes

In this study, pure tetragonal zirconia (t-ZrO2), with an average size of approximately 7 nm, was prepared by a modified hydrothermal method using zirconium nitrate (Zr(NO3)4) as the zirconium source and glycerol as the additive. The effects of pH and glycerol content on the phase and morphology of the ZrO2 were investigated, and the mechanism is discussed herein. The tetragonal phase gradually increased with an increase in pH, while the grain size of the powder gradually decreased. The effect of glycerol addition on the crystal phase of the powder was also investigated, and the results showed that the monoclinic phase gradually decreased with an increase in the amount of glycerol added. With a glycerol to zirconium molar ratio of 3:1, a single tetragonal phase was produced. In addition, a high-performance ZrO2 ultrafiltration membrane was prepared by coating the inner surface of the tubular ZrO2 membrane. The characterization results show that the thickness of the membrane was approximately 1.5 μm, the pure water flux was approximately 84 L m−2 h−1·bar−1, and the molecular weight cut-off was approximately 7000 Da. The reproducibility of the high-performance ZrO2 ultrafiltration membranes was also evaluated. It was found that the synthesised ZrO2 membrane has high reproducibility and stability.

Controllable synthesis of pure monodispersed zirconia nanopowders with tetragonal phase

AbstractNanopowders of pure zirconia have been synthesized using citric acid (CA)‐assisted lamellar liquid crystal template method. The microstructure of the zirconia powder prepared at the different mole ratios of CA to zirconium oxynitrate (ZN) was characterized by FT‐IR, X‐ray diffraction (XRD), laser particle size analyzer, Raman spectroscopy, and scanning electron microscope (SEM) methods. The phase structure of the sodium dodecyl sulfate (SDS)/C10H21OH/H2O system before and after adding mixing solution CA and ZN was determined by POM (Polarizing Optical Microscope). The results show that lamellar structure of the SDS/C10H21OH/H2O system after adding mixing solution CA and ZN is stable. The presence of CA inhibits agglomeration and growth of zirconia particle. The crystallite size of zirconia powders decreases and agglomerates lowly with addition of CA. Fourier transform infrared spectrometry (FI‐IR) analyses reveal that the structure of chelating organic complex is maintained in zirconia structure at high‐temperature calcination to cause oxygen vacancies which stabilizes the tetragonal phase of zirconia. The zirconia powders remained the single metastable tetragonal phase at the molar ratios of CA to ZN ranging from 1:3 to 5:1. The crystallite size of zirconia with spherical morphology varied from 32.2 to 20.1 nm with the increase of the molar ratio of CA to ZN in the range of 1:3 to 5:1.

Tribological and Mechanical Properties of Multicomponent CrVTiNbZr(N) Coatings

Multi-element material coating systems have received much attention for improving the mechanical performance in industry. However, they are still focused on ternary systems and seldom beyond quaternary ones. High entropy alloy (HEA) bulk material and thin films are systems that are each comprised of at least five principal metal elements in equally matched proportions, and some of them are found possessing much higher strength than traditional alloys. In this study, CrVTiNbZr high entropy alloy and nitrogen contained CrVTiNbZr(N) nitride coatings were synthesized using high ionization cathodic-arc deposition. A chromium-vanadium alloy target, a titanium-niobium alloy target and a pure zirconium target were used for the deposition. By controlling the nitrogen content and cathode current, the CrNbTiVZr(N) coating with gradient or multilayered composition control possessed different microstructures and mechanical properties. The effect of the nitrogen content on the chemical composition, microstructure and mechanical properties of the CrVTiNbZr(N) coatings was investigated. Compact columnar microstructure was obtained for the synthesized CrVTiNbZr(N) coatings. The CrVTiNbZrN coating (HEAN-N165), which was deposited with nitrogen flow rate of 165 standard cubic centimeters per minute (sccm), exhibited slightly blurred columnar and multilayered structures containing CrVN, TiNbN and ZrN. The design of multilayered CrVTiNbZrN coatings showed good adhesion strength. Improvement of adhesion strength was obtained with composition-gradient interlayers. The CrVTiNbZrN coating with nitrogen content higher than 50 at.% possessed the highest hardness (25.2 GPa) and the resistance to plastic deformation H3/E*2 (0.2 GPa) value, and therefore the lowest wear rate was obtained because of high abrasion wear resistance.

Simulation of the Ionic Conductivity, Thermal Conductivity and Thermotransport of Doped Zirconia Using Molecular Dynamics

This study focuses on a number of transport phenomena in yttria-stabilised zirconia (YSZ). A molecular dynamics simulation based on the Green-Kubo formalism is applied to calculate the lattice thermal conductivity, oxygen diffusion coefficient, ionic conductivity and thermotransport at different concentrations (i.e., 4, 8, 10, 12, 16 and 20 mol% of Y 2 O 3 ) over a temperature range from 700 K to 1500 K. The results show that the YSZ has a low thermal conductivity in comparison with pure zirconia. The oxygen tracer diffusion coefficient, as calculated from the mean square displacements, and also the ionic conductivity show an activation energy of 0.85eV. The Onsager cross coefficient associated with thermotransport is negative, meaning that the drift of anions in a temperature gradient would be from a cold region to a hot region. All of the simulation results presented show reasonable agreement with available experimental data.

Insight of precursor concentration, particle size and band gap of zirconia nanoparticles synthesized by co-precipitation method

Zirconia (ZrO2), an inorganic material, is a very fascinating material due to its high mechanical strength and fracture toughness. The synthesis is carried out by using co-precipitation method using optimum content of zirconium oxychloride octahydrate (ZrOCl2.8H2O) with NaOH solution at calcination temperature of 700°C. The synthesized samples were characterized to ensure structural, functional, morphological and chemical composition by several techniques. The monoclinic structure has been confirmed from XRD, SAED and Raman spectra. The Zr-O stretching vibration and Zr-O2-Zr bending vibrations were confirmed through FTIR analysis. The well dispersed particles with spherical morphology were established through SEM and TEM analyses. EDX spectra confirmed the formation of pure zirconium oxide. The band gap was calculated with the help of UV-Vis spectra and particle size was determined form XRD data using Debye Scherrer’s equation. The variation of band gap and particle size compared with different concentrations of precursor solution was studied.&#x0D; BIBECHANA 18 (2021) 1-9

Model of Cathode Spots Crater Formation and Deuterium Desorption Process on Zirconium Deuterium Electrode

In this article, the model including cathode spot process and deuterium desorption process on zirconium deuterium cathode is developed. Five kinds of particle fluxes on cathode surface and three mechanisms affecting deuterium diffusion in cathode are considered. The model not only describes the deformation of cathode metal, but also describes the variation of deuterium concentration with time. On pure zirconium cathode, the mean charge state is larger but on zirconium deuterium cathode, the total ion number density is larger since there are additional deuterium ions, and simulation results show the discharge currents are very close on the two cathodes, the energy flux density on ZrD0.66 cathode is larger so cathode spot crater develops faster on ZrD0.66 cathode. Ablation rates caused by different mechanisms are calculated and the results show in cathode spot development process, mass loss caused by evaporation is ignored, most of the liquid metal will resolidify on cathode surface, and droplets are the main reason for cathode ablation. The ablation rates due to the ejection of droplets are close to experimental results. The ratios of deuterium ion from different mechanisms in this process are also calculated and it is 93.5% in simulation. Simulation results are in agreement with the other researchers’ works.

Strengthening effect of grain and twin boundaries in zirconium bi-crystal micropillars

ABSTRACT In this work, the effect of crystallographic orientations and the strengthening due to grain/twin boundaries were investigated by uniaxial compression of single- and bi-crystal micropillars of pure zirconium (Zr) with ≥99.9% purity. Micropillars fabricated using focused ion beam (FIB) milling were compressed using a flat punch tip in a nanoindenter to obtain stress–strain curves for individual orientations of Zr. Only near-basal-oriented samples were deformed by multiple slip, while samples with other orientations were deformed by a single slip. Bi-crystal samples had significantly higher flow stress than single-crystal samples – the increment in flow stress arising from grain boundaries being higher than that arising from twin boundaries. Our analysis shows that while twin-boundary strengthening can be explained based on a size effect according to the Hall-Petch equation, the higher strengthening effect of grain boundaries appears to arise from a combination of a sample-size effect as well as dislocation accumulation at boundaries.