Addition Of ZrO2 Research Articles

Phosphate adsorption and desorption on two-stage synthesized amorphous-ZrO2/Mg–Fe layered double hydroxide composite

Although different treatment techniques have been developed to eliminate phosphorus contamination, including for wastewater treatment, treated water often fails to meet quality regulations. Amorphous-ZrO2/Mg–Fe layered double hydroxide (LDH) composites with different molar ratios (Zr/Fe = 0.5–2) were prepared in two-stage synthesis by the combination of coprecipitation and hydrothermal methods. The requirement of high-temperature calcination in the LDH for phosphate adsorption could be eliminated by the synthesis of the composite. Moreover, the phosphate adsorption ability of the composite was higher than that of the individual LDH and amorphous-ZrO2. The addition of ZrO2 increased the phosphate adsorption ability of composite at low pH. The adsorption capacity was increased by decreasing the pH and increasing the temperature (from 290 to 324 K). The bicarbonate (HCO3−) was the most competitive anion for phosphate adsorption. The pseudo-second-order model provided the best description of the kinetic adsorption data. Furthermore, the adsorbed phosphate was easily desorbed by 1 N of NaOH solution. The results suggest that the amorphous-ZrO2/Mg–Fe LDH composite is a promising material for phosphate removal and recovery from wastewater. Ongoing research will investigate the performance of the composite for real wastewater as well as the mechanism of phosphate adsorption on the composite surface.

Effect of CO2 Laser on Glazed Zircon Surface Complemented by ZrO2 Oxide

In this paper, the effect of CO2 laser on glaze-dental Zirconia ceramics after adding ZrO2 nanoparticles to glaze is introduced, and its improvement methods are studied. Specimens have been prepared using CAD/CAM dental machines and sintered at 1530o-C. Then the surface was glazed with VITA glaze plus (5% and 10%) Nano ZrO2. A 15W continuous CO2 laser was used as the indicator power to irradiate the glaze layer. The main phase of the ceramic substrate is tetragonal Zirconia, and the alumina content in the corundum phase is a certain percentage. The appearance of the varnish on the ceramic substrate changes the X-ray diffraction pattern through the appearance of new phases, which changes the crystallite size and the percentage of lattice strain. The range of grain size measured by atomic force microscopy was 88.46 nm to 62.18nm. In addition, the surface roughness was changed due to the appearance of crystal cores and grain growth. In addition, the addition of ZrO2 and laser irradiation changed the residual stress on the surface, which was reflected in the hardness value increased from 575 kg/mm2 to 1215 kg/mm2 after the laser treatment with the addition of 5% ZrO2. Generally, in terms of the structure and hardness of the surface of the glaze layer, the addition of 5% ZrO2 is better than 10%. SEM tests also showed no cracks in the central part of the treated area. These characteristics increase hardness.

Optical and nuclear radiation protection characteristics of lithium bismo-borate glasses: Role of ZrO2 substitution

The current study is intended to examine the optical, structural and photon/neutron shielding qualities of a group of different ZrO2 content doped 60B2O3 +20Bi2O3+(20-x)Li2O + xZrO2 glasses, labeled as BBLZ1, BBLZ2, BBLZ3, BBLZ4 and BBLZ5 manufactured via the melt quenching technique. The specific gravity of the glasses was boosted with increasing ZrO2 additive and molar volume exhibited the opposite trend versus the density. XRD patterns were obtained to reveal the amorphous structure of the glasses. Spectra of optical absorption for BBLZ glasses were recorded in the wavelength region 200–1100 nm. The direct band gap (Eg) values dropped from 4.24 to 3.87 eV with the boosting ZrO2 content while the indirect Egs declined from 3.78 to 3.18 eV. The refractive index grew as the ZrO2 substitution ratio enhanced. To determine photon shielding parameters of BBLZ glasses, the mass attenuation coefficients (MAC) were gained viz Py-MLBUF online program for the 0.015–15 MeV gamma ray energies. Several shielding parameters of BBLZ glasses such as Half Value Layer (HVL), Exposure Buildup Factor (EBF) and Mean Free Path (MFP) were reached using MAC values. The highest MACs differ from 68.188 cm2/g to 0.036 cm2/g for BBLZ5 glass while the lowest μ/ρ values varying from 69.413 cm2/g to 0.036 cm2/g belong to the BBLZ1 glass. The thinnest MFP and HVL values were observed in the BBLZ5 glass with the highest ZrO2 contribution (4 mol %). Adding ZrO2 to the fabricated glasses reduced photon buildup. BBLZ5 glass was determined to be the safest neutron shield due to its high density. It can be concluded that ZrO2 addition with increasing rates to lithium bismo-borate glasses reinforced both optical properties and nuclear radiation security qualities.

Composite film based on potato starch/apple peel pectin/ZrO2 nanoparticles/ microencapsulated Zataria multiflora essential oil; investigation of physicochemical properties and use in quail meat packaging

In this study, a composite film made of potato starch (St)/apple peel pectin (Pec) was prepared. The St/Pec film was modified with microencapsulated Zataria multiflora essential oil (MEO) and zirconium oxide (ZrO2) nanoparticles (St/Pec/MEO/ZrO2). The physicochemical and antimicrobial properties of the film were studied. The optimum films were used for packing quail meat. According to the results, the addition of MEO to the film increased the moisture content while the addition of ZrO2 to the film decreased the moisture content. Water vapor permeability increased with increasing MEO and decreased with increasing ZrO2 concentration. The MEO and ZrO2 greatly increased the antioxidant properties, melting point and glass temperature of the film. According to the SEM (Scanning electron microscope) images, the encapsulated essential oil and ZrO2 created porosity in the film structure. The FTIR (Fourier-transform infrared) results revealed the electrostatic interactions between the composite components. XRD (X-ray diffraction) study showed that the MEO reduced the crystal structure of the film. Packaging of quail meat with St/Pec based active films increased shelf life of the meat. The film contained the highest amount of MEO and ZrO2 had the greatest effect on the stability of quail meat. The study of releasing the essential oil from the film showed that the release of the essential oil occurs gradually. The encapsulation of the essential oil has increased the effectiveness time of the essential oil.

The corrosion kinetics of cordierite-based ZrO2 composites obtained from natural zeolite in dilute HCl acid solution

Being a versatile ceramic, which can be used in various applications, cordierite has always been subject to optimization and research. Nevertheless, the corrosion resistance of the ceramic, synthesized from natural zeolite, has not been widely investigated. In this study, cordierite with 2:2:5 compositions of MgO/Al2O3/SiO2, respectively, was obtained from the natural zeolite. Following sintering at 1250°C for 1 h, of cordierite with 10 and 20% amount of added zirconia (ZrO2), the mechanical properties exhibited proportional amelioration, accompanied by an enhanced homogeneity and reduced microcracks. The corrosion properties were investigated via the weight loss method in 2 vol. % and 5 vol. % HCl acid solutions maintained for up to 480 h at 25, 50, and 75°C. The corrosion kinetics were evaluated from corrosion curves, followed by a calculation of the activation energies of corrosion. The results revealed that ZrO2 addition enhances the resistance, with an optimum observed for the 10% zirconia doped cordierite samples, with varying activation energies between 113 kJ/mol for 5 vol. % HCl acid solution and 119 kJ/mol for 2 vol. % HCl acid solution.

Toughening cemented carbides by phase transformation of zirconia

Yttria partially stabilized zirconia was introduced into WC-Co cemented carbides to enhance their mechanical performance. The hardness and fracture toughness were improved simultaneously with the addition of ZrO2. Particularly, the fracture toughness of the cemented carbides was significantly enhanced. The mechanism was mainly attributed to the stress-induced phase transformation of tetragonal ZrO2 to monoclinic ZrO2. This phase transformation introduced a compressive stress field and deflected the micro-cracks. In addition, the ZrO2 particles dispersed homogeneously in the WC skeleton and had good interfacial bonding with both WC and Co phases, which was beneficial to the mechanical properties of the cemented carbides. This study provides a new promising approach to break the trade-off between the hardness and fracture toughness of cemented carbides to achieve excellent comprehensive mechanical properties. The new strategy will be also promising to be applied in a variety of cermets or ceramic-based composites.

Effect of zirconia on low cycle fatigue and energy absorption of molybdenum alloy

Pure molybdenum and ZrO2 dispersion strengthened Mo alloy were prepared by liquid-liquid doping method. The effects of adding ZrO2 on their microstructure and properties were investigated by tensile test and low cycle fatigue (LCF) test at room temperature, and the fracture mode and energy absorption were analyzed. The research shows that ZrO2 can refine the grain size and increase the recrystallization temperature of molybdenum alloy. The enhancement of yield strength by ZrO2 is mainly reflected in grain boundary strengthening. The tensile fracture mode is related to grain size, and changes from transgranular fracture to transgranular-intergranular fracture with the decrease of grain size. At the initial stage of the cycle, the increase of strain amplitude changes the cyclic hardening into cyclic softening, and the addition of ZrO2 accelerates the cyclic hardening/softening. With the increase of strain amplitude, the loading energy and absorption energy of a single stable cycle increase, while the unloading energy is basically unchanged. ZrO2 can increase the total fatigue absorption energy of molybdenum alloy at the same strain amplitude, and the single cycle absorption energy is lower than that of pure Mo, thus increasing the fatigue life.

Mixed Films Based on MgO for Secondary Electron Emission Application: General Trends and MOCVD Prospects

Doping process is widely used to improving emission performance of MgO films thicker than 10 nm via assisting the surface recharge and changing in electron structure. The present paper briefly reviews this strategy in a search for the new materials and structures being effective for secondary electron emission (SEE) and their diagnostics. Then, Metal-Organic Chemical Vapor Deposition (MOCVD) coupled with the specially selected precursor is suggested here as a new technique that transforms the refractory oxides to nanoscale, defect-disordered materials able to solid-solid interaction at 450 °C. Primary experiments have been performed for demanded mixed films based on MgO with ZrO2 and CeO2 additions. A dopant impact on facilitating the formation of oxygen vacancies in the host oxide and on the features of new mixed phases have been studied by new diagnostic means, based primarily on chemical method of differential dissolution. The method brought out the effective solvents that were the probes for identifying the nanoscale and amorphous phases possessing by the different defects on the surface of MgO films and determining contents of these phases. This approach allowed us to explain the origin of mixed phases and to estimate contribution of each from them in the macroscopic SEE properties.

Sinterability and Luminescence Property of the MgO-YAG:Ce Phosphor Ceramic with Sintering Aids

MgO-YAG:Ce phosphor ceramics with the addition of Y2O3, SiO2, TiO2 and ZrO2 as sintering aids were developed from commercial powders by hot-pressing. In this work, the effects of Y2O3, SiO2, TiO2, ZrO2 on the phase composition, microstructure, sinterability and luminescence intensity of MgO-YAG:Ce phosphor ceramic were investigated. By comparison, the relative density of MgO-YAG:Ce phosphor ceramic with 2 wt.% SiO2 was satisfying, reaching 98.4%, and the luminescence intensity reached the maximum. Because SiO2 and MgO react to form interstitial solid solution Mg2SiO4, which leads to the increase of the grain boundary energy of the MgO matrix, thereby increasing the sintering performance of MgO-YAG:Ce phosphor ceramics. And SiO2 does not react with YAG, maintaining the excellent luminescence properties of YAG itself.

Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering

Effects of ZrO2 and Al2O3 Addition on the Physical Properties of Cu-Mo-Cr Alloy by Liquid Phase Sintering

Effect of ZrO2 addition on electrical and mechanical properties of B2O3–PbO–Li2O3 glasses

In this work, the electrical and mechanical properties of 40B2O3+40PbO+ 20Li2O3+xZrO2 (where x = 0.0, 0.25, 0.5, and 1.5 wt%) were experimentally investigated. The electrical and dielectric data were measured in the temperature range of 20–300 °C. Based on Makishima–Mackenzie's model, a total of dissociation energy (Gt) and the ionic packing density (Vt) for the investigated specimens were calculated. Then, the mechanical features, including Poisson's ratio and elastic moduli, were calculated. It was found that Vt decreased in the range of 0.3708–0.3051 m3 mol−1, while the Gt was enhanced in the range of 34.74 × 106 - 35.8803 × 106 kJ m−3 as the ZrO2 content increased. Young's modulus changed from 25.7637 to 21.8953 GPa. At the same time, the shear modulus was found to change from 11.4460 to 10.4782 GPa. The bulk modulus varied from 11.464 to 8.0167 GPa; the longitudinal modulus varied from 26.7255 to 21.9877 GPa. The values of Poisson's ratio were found to change from 0.1254 to 0.0448. The electrical results revealed that the addition of ZrO2 minimized the electrical conductivity in the temperature range of 20–300 °C; besides, it maximized the activation energy.

Effects of various sintering additives on the properties of β-SiAlON–SiC ceramics obtained by liquid phase sintering

β-SiAlON–SiC ceramics were obtained by the liquid phase sintering method under N2 atmosphere. The effects of various sintering additives (including Y2O3, ZrO2, ZrSiO4, Suzhou kaolin, petalite, and cordierite) on the structure, thermal expansion coefficients (room temperature–1000 °C), and high-temperature (1400 °C) mechanical properties of β-SiAlON–SiC ceramics were studied. The results indicate that 10 wt% Y2O3 promoted the formation of columnar β-SiAlON crystals resulting in samples with the highest room-temperature bending strength of 103.7 MPa, but an increased thermal expansion coefficient of 4.7 × 10−6 °C−1. A 10 wt% addition of ZrO2 (or ZrSiO4) fractured the samples greatly due to the transformation of cubic ZrO2 to monoclinic ZrO2 during the cooling stage, and the use of Y2O3 as a stabilizer was indispensable for the ZrO2-containing sintering additives. The combined use of Y2O3, ZrO2, and ZrSiO4 exhibited a better effect on the densification of the ceramics than the other sintering additives, and the lowest water absorption of 12.1% was obtained. Y2O3-containing additives caused severe oxidation of the β-SiAlON–SiC ceramics at 1400 °C, decreasing the high-temperature bending strength to 10.3–25.3 MPa. Suzhou kaolin, petalite, and cordierite were also helpful for increasing the nitridation ratio by carbothermic or aluminothermic nitridation of SiO2 and endowed the samples with low thermal expansion coefficients of 3.7–4 × 10−6 °C−1. The addition of Suzhou kaolin resulted in the highest high-temperature bending strength of 50.5 MPa by improving the oxidation resistance of β-SiAlON–SiC ceramics.

Effects of ZrO2 Addition Amount on Microstructure and Mechanical Property of WC-6Co Prepared by Spark Plasma Sintering

Effects of ZrO2 Addition Amount on Microstructure and Mechanical Property of WC-6Co Prepared by Spark Plasma Sintering

Zirconia-Alumina Composites Obtained by Centrifugal Slip Casting as Attractive Sustainable Material for Application in Construction.

This paper focuses on the possibility of adapting the centrifugal slip casting method to obtain zirconia–alumina composite materials in the form of finished tube-shaped products. These types of products, due to their unique properties, can be utilised, for example, in the transport of aggressive substances, even in extreme temperatures or corrosive conditions. The study reports on the two series of zirconia–alumina composites differing in the content of ZrO2—2.5 and 25 vol%. The fabricated and sintered materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and stereological analysis. Moreover, a life cycle assessment (LCA) was provided in accordance with the requirements of the ISO 14044 and EN 15805 standards. The obtained data clearly show that the centrifugal slip casting method allows obtaining samples with high density and extremely uniform distribution of the ZrO2 phase in the alumina matrix. The stereological analysis results proved also that the addition of ZrO2 is effective in reducing the growth of Al2O3 grains during the sintering process. The phase analysis carried out by means of XRD showed that during the sintering process, in the case of composites with a lower ZrO2 content (2.5 vol%), the monoclinic to tetragonal transformation of ZrO2 was total, while for samples containing 25 vol% ZrO2, the monoclinic phase remained in a small amount in the final product.

ВЛИЯНИЕ МОДИФИЦИРУЮЩЕЙ ДОБАВКИ ОКСИДА ЦИРКОНИЯ НА СВОЙСТВА КЕРАМИЧЕСКИХ МАТЕРИАЛОВ СИСТЕМЫ Y2O3–Al2O3–SiO2, ПОЛУЧЕННЫХ ЗОЛЬ-ГЕЛЬ МЕТОДОМ

The effect of the modifying additive ZrO2 on the rheological properties, the processes of structure and phase formation of the compositions of the Y2O3–Al2O3–SiO2 system obtained by the sol-gel method has been investigated. It was found that the temperature range of crystallization of the compositions of the Y2O3–Al2O3–SiO2 system with the addition of ZrO2 is 1020–1270 °C and with an increase in the concentration of zirconium oxide, the amount of the main crystalline phase of yttrium pyrosilicate (β-Y2Si2O7) decreases and the concentration of the zirconium-containing phase – the tetragonal modification of zirconium oxide and zirconium silicate ZrSiO4 -increases.

Synthesis of Zirconia Doped Molybdenum Oxide as Efficient Catalysts for Ultrasound Assisted Synthesis of Substituted Pyrazoles

To explore green methodology for the synthesis of mixed oxide, its catalytic activity and temperature stability of series of ZrO2/MoO3 and ZrO2 were prepared by sol-gel method and characterized by XRD, FT-IR, X-ray photoelectron spectroscopy (XPS), temperature programmed Desorption (TPD), Raman spectroscopy and transmission electron microscopes (TEM). These mixed oxides were showed high stability with nanocrystalline nature. Due to highly acidic nature of the catalysts, ultra sound assisted synthesis of substituted pyrazoles was carried out successfully with high yield. The reaction was carried out in solvent free medium, which showed green approach and energy saving reaction. Condensation of dibenzoyl methane and hydrazine to form substituted pyrazoles with 97.7% yield. The acid strength and acid amount of synthesized catalysts were determined by temperature programmed desoprtion (TPD), incorporation of zirconia into the molybdenum, network has changed its surface acid properties due to the Zr2+ and Mo6+ ions. After addition of ZrO2 on MoO3, it showed weak and strong acid sites.

Evaluating the tribological properties of aluminium based hybrid composites reinforced with Al2O3 & ZrO2 nano particles

Metal matrix composites are being increasingly identified in now a days as new wear resistant material. The main purpose of this paper is to investigate the wear and hardness of the composite material Al-6061 alloy strengthened with Al2O3 and ZrO2 particulate and constructed with the help of stir casting method. The wear rate and frictional properties of the composite were conducted in pin and disk type of wear testing machine. The investigation was carried out with constant length of sliding distance and sliding velocity over different load ranges for aluminium metal matrix composite. The testing result indicated that the wear resistance increases when there is increase in the load. Additionally, an effort was made by keeping Al2O3 as constant of 2.5% along with increase in 1, 2, 3 and 4% of ZrO2. It was observed that, the strengthened aluminium metal matrix in addition of Al2O3 and ZrO2 decreases the range of damage due to friction.

External Solvent‐Free Catalytic Hydrodeoxygenation of Softwood Lignin to Aromatics over Carbon–ZrO2 Supported Ni/MoS2 Catalysts

AbstractThis work aims to convert black liquor‐ derived softwood lignin into industrially vital aromatic compounds by catalytic hydrodeoxygenation (HDO), without the use of external solvent. Lignin melts serve as the solvent itself under HDO conditions. Activated carbon supported NiMoS2 catalysts are prepared by a water/oil micro–emulsion method and the required support acidity is tailored by addition of ZrO2 (10–50%) to the support. The maximum deoxygenation of 82.2% is observed along with a monomer yield of 69.1% in 3 h reaction time, when 10% ZrO2 is added to the carbon support. The yield of monomers is distributed in the following order: alkyl phenolics (23.1%) > guaiacolics (18.1%) > aromatic hydrocarbons (17.5%) > alkanes (10.5%). Interestingly, aromatic hydrocarbons yield increases with increase in time. The catalyst is found to be stable, without any significant loss in the activity and product selectivity when tested for up to five reaction cycles.

Effect of ZrO2 Addition on Microstructure and Mechanical Properties of Al-Zn-Mg Alloy Matrix Composite

Aluminum – based metal matrix composite are widely used in industrial applications compared with conventional and unreinforced alloy. The composite materials usually exhibit a higher strength both at elevated and ambient temperature, as well as wear resistance. The production of composite materials which contain different weight percentage of ZrO2 (0.5, 1.5 and 2.5wt %) by stir casting process. The mechanical properties of the base alloy and composite were evaluated by using tensile and hardness tests. The microstructure inspection by optical microscopy, scanning electron microscope and energy dispersive spectroscopy (EDS) were utilized to study the fracture surface topography. The results represent that the hardness, strength of yield and tensile strength increased with increasing the weight % of ZrO2 to 2.5 % while the elongation decreased. The microstructure inspection by optical microscope shows that the dendrites structure and the particles distribution in matrix without any voids. Furthermore, the grain size refining with the weight percentage of weight reinforcement elevated.

Material modifications enhancing the antibacterial properties of two biodegradable poly(3-hydroxybutyrate) implants

The aim of this study was to evaluate the antimicrobial efficacy of adding a gentamicin palmitate (GP) coating and zirconium dioxide (ZrO2) to biodegradable poly(3-hydroxybutyrate) (PHB) to reduce biofilm formation. Cylindrical pins with and without a coating were incubated in Müller-Hinton broth inoculated with 2 × 105 colony-forming units (CFU) ml-1 of Staphylococcus aureus for 2 d or 7 d, then sonicated to disrupt biofilms. Pure PHB (PHB + GP) and PHB pins with ZrO2 added (PHBzr + GP) were coated with GP and compared with PHB pins lacking a coating (PHB). Cells (CFU) were counted to quantify the number of bacteria in the biofilm and a cell proliferation assay was employed to evaluate metabolic activity, and scanning electron microscopy (SEM) was performed to visualize the structure of the biofilm. After 2 d of incubation there were significantly more cells in biofilms on PHB pins than PHB + GP and PHBzr + GP pins (p < 0.0001), and cells in the sonication fluid obtained from GP-coated pins exhibited significantly lower metabolic activity than cells from uncoated PHB pins (p < 0.0001). After 7 d of incubation metabolic activity was lowest for PHBzr + GP, with significant differences between PHB and PHBzr + GP (p = 0.001). SEM revealed more cells attached to the surface, and more structured biofilms, on pins without a coating. Coating pins with GP significantly reduced early biofilm formation on PHB implants. This could lower the potential risk of surgical site infections when using PHB implants. Addition of ZrO2 might further enhance the antibacterial properties. Such modification of the implant material should therefore be considered when developing new biodegradable PHB implants.