Addition Of ZrO2 Research Articles

Synthesis and slurry spray coating of barium strontium alumino silicate on SiC substrate

Barium strontium alumino silicate (BSAS); (Ba0.6Sr0.4Al2Si2O8) was synthesized through solid state reaction between BaCO3, SrCO3, Al2O3 and SiO2 subjected to wet milling in isopropanol for about 24 h. The sequence of the solid state reaction was studied by subjecting to DG/DTG from room temperature to 1550 °C. The crystallographic phase evolution was confirmed by X-ray diffraction of the powders calcined in the range 1000 to 1300 °C for 2 h. The monoclinic celsian phase obtained at 1300 °C, pelletized through uniaxial pressing was sinterable to 67 to 78% density in the temperature range of 1300 to 1500 °C. The density improved to 75 to 94% after ball milling for 76 h, while ZrO2 addition further improved the density by 2%. The celcian phase of BSAS was dispersed in isopropyl alcohol, milled for about 24 h and spray coated on to plain SiC and mullite precoated SiC substrates. Sintering of coated samples and characterization for weight gain/loss, microstructure, scratch test prove that mullite + BSAS coating is more effective than single layer coating of BSAS on SiC substrates.

Effects of ZrO2 nanoparticle content on microstructure and wear behavior of titanium matrix composite

The Ti-ZrO2 nanocomposites were fabricated by powder metallurgy route. The influence of ZrO2 additions on the microstructure and properties of the Ti-based composites were examined by X-ray diffraction, scanning electron microscopy, microhardness and wear properties tests. The result showed that spread of ZrO2 nanoparticles in the Ti matrix. XRD refers to no new phase are formed between Ti and ZrO2 during the sintering process. In addition, a good microstructure is achieved. The densification behavior of the sintered nanocomposites is increased with increasing ZrO2 percent. The highest microhardness was measured as 570 HV for titanium matrix nanocomposites fabricated by using 10%wt of ZrO2 nanoparticles content. 290 HV was obtained for the titanium matrix. Results showed that the sliding wear rate increase with increasing the normal load and decrease via increasing the addition of ZrO2 nanoparticles. In addition, the friction coefficient decreases with increasing the normal load and via increasing the addition of ZrO2 nanoparticles. The microstructure refines due to ZrO2 addendums illustrated a considerable function in the wear behavior of the Ti matrix.

Tensile, compressive and heat transfer analysis of ZrO2 reinforced aluminum LM6 alloy metal matrix composites

In the present investigation, aluminum LM6 alloy is used as a matrix and it was reinforced with various weight fractions of ZrO2 Such as 0, 3, 6, 9 and 12 wt%. The composite materials were cast using the stir casting method. The various stir cast samples were subjected to Energy Dispersive Spectrometry (EDS) analysis, mechanical and thermal analysis. The mechanical analysis of tensile and compressive strength was carried out for the five various weight proportions of ZrO2. The EDS analysis confirmed that the presence of aluminum and, ZrO2 particles in developed composites. Tensile and compressive strength was increased by the addition of ZrO2. In this work, mainly deals with the analysis of heat transfer for the newly developed aluminum-based composite materials when it is used as a pin fin for varying the weight percentages of ZrO2 with the aluminum particles. The Heat transfer analysis was carried out for the Aluminum LM6 matrix in addition to that varying the weight proportions of ZrO2. The efficiency and effectiveness of each fin were measured during this test. From the analysis, it was revealed that heat transfer rate was increased for the increased weight fraction of ZrO2. Similarly, the efficiency of the pin and effectiveness was increased for the increasing weight percentages of zirconium dioxide. A similar test was carried out for the same materials for varying the input voltage and current. From that test, it was identified that heat transfer is gradually increased for the increasing supply of voltage and current.

Mechanical and Optical Properties of ZrO2 Doped Silicate Glass Ceramics

In the present study, we report the physical and optical properties of low-cost glass (soda-lime silicate glass) fabricated from local minerals, obtained from Hazara division Khyber Pakhtunkhwa, Pakistan. Zirconium dioxide (1–3%) was added as a nucleating agent to investigate its effect on phase, density, hardness, and optical properties of soda-lime silicate glass. In the obtained glass-ceramic materials, the major crystalline phase was cristobalite. It was found that an increase in ZrO2 content and heat treatment of the samples, resulted in an increase in bulk crystallization of the samples. The mechanical properties were found to be improved with ZrO2 addition. The bandgap of the sample was in the range 3.78–4.09 eV.

Catalytic performance of Pd catalyst supported on Zr:Ce modified mesoporous silica for methane oxidation

Catalytic oxidation of methane is critical for exhaust after-treatment systems where cold-start emissions and lean combustion still pose serious challenges. In this work, the effect of support materials on the complete catalytic oxidation of methane over palladium is studied in dry and wet conditions. A series of metal oxides (CeO2, ZrO2, n-SiO2) and mixed metal oxides (Zr0.65Ce0.35O2, Zr0.33Ce0.33/n-Si0.33O2, Zr0.66Ce0.17/n-Si0.17O2) supported Pd catalysts were synthesized, characterized and tested for methane oxidation. Pd/n-SiO2 was found to be highly active catalyst with the lowest initial (T10%) and final (T100%) conversion temperatures as compared to Pd supported on CeO2 and ZrO2. Methane combustion over mixed oxide supports, prepared with different ratios of Zr:Ce:Si, showed improved catalytic performance. Catalyst with equal ratios of Zr:Ce:Si (Pd/Zr0.33Ce0.33/n-Si0.33O2) showed similar performance to that of Pd/n-SiO2 with approximately ~8 (±2) °C higher light-off temperature. Additionally, cyclic wet (8 vol% H2O) and dry reactions were performed to evaluate the hydrothermal stability and activity regeneration when switching from wet to dry conditions. Optimal addition of ZrO2 and CeO2 to n-SiO2 resulted in higher stability of palladium catalyst over wide ranges of temperatures (350–600 °C). Catalysts were characterized by various analytical techniques, including TEM, XRD, XRF, N2-BET, O2-TPD, and CO chemisorption. TEM results demonstrate that mixed oxide support stabilized Pd nanoparticles, and n-SiO2 encapsulation prevented sintering and deactivation. Activity tests and characterization results demonstrate overall superior catalytic properties of Pd supported on Zr0.33Ce0.33/n-Si0.33O2. This catalyst can be quite promising for practical applications due to its high activity for total methane oxidation and excellent thermal stability.

Effect of ZrC and ZrO2 Additions on the Microstructure and Properties of ZrB2–SiC Ceramics

We have studied the effect of ZrC and ZrO2 additions on the microstructure and properties of ceramic composites based on ZrB2???5% SiC, produced by pressure-sintering mechanically activated powders at a temperature of 1600??C. The results demonstrate that the addition of ZrO2 increases the density, hardness, and fracture toughness of ceramic composites based on ZrB2???5% SiC. In particular, the KIc of the ZrB2???5% SiC ceramic is 4.6 ?? 0.3 MPa m1/2 and that of the composite containing 20% ZrO2 is 7.3 ?? 0.4 MPa m1/2.

Effects of Transition Metal Oxides ZrO2, Y2O3, and Sc2O3 on Radiative Heat Transfer of Low-Reactive CaO-Al2O3-Based Mold Slag

To control heat transfer between the solidifying shell and the water-cooled mold during continuous casting, the transition metal oxides, ZrO2, Y2O3, and Sc2O3, were separately added into the developed low-reactive CaO-Al2O3-based mold slags to investigate the effect on radiation heat transfer. Two kinds of master mold slags were taken into account, one included 18 pct Al2O3 and 18 pct SiO2, and the other one included 28 pct Al2O3 and 8 pct SiO2. The slag viscosity and melting temperature were measured with rotating cylinder viscometer and hemisphere-point method, respectively. The optical parameters of the slag films having different contents of transition metal oxides were measured by Fourier transform infrared spectrometer, and an optical-process model was constructed to consider the radiation from the shell surface and hot and cold sides of the solid films to the mold plate. When ZrO2, Y2O3, and Sc2O3 contents up to 4 pct, the viscosity at 1573 K fluctuated in the range of 0.05 Pa s, the melting temperature varied within a range of 15 K, except for the case of 2 pct Sc2O3, for which the melting temperature was 27 K lower than that of the master mold slag with 8 pct SiO2 and 28 pct Al2O3. The incorporation of the three transition metal oxides up to 4 pct did not have a notable effect on the viscosity or melting temperature. The addition of ZrO2 and Y2O3 effectively decreased the radiation, whereas Sc2O3 had no direct relationship with radiation. When the ZrO2 (Y2O3) concentration was increased from 0 to 4 pct, the reduction rate of radiation transfer was 26.6 pct (13.3 pct) for the mold slag containing 18 pct Al2O3 and 18 pct SiO2. The current study provides a new direction for developing low-reactive mold slag and reducing heat transfer during continuous casting.

The activation and conversion of carbon dioxide on the surface of zirconia-promoted ceria oxides

This study reports the conversion of carbon dioxide (CO2) by ceria (CeO2)-zirconia (ZrO2) composites with various ZrO2 contents (0, 20, 50, 80 and 100 %). The modification introduced by ZrO2 altered the structural properties of the ceria samples, affecting their reducibility and subsequent activity to convert CO2. The characterisation results showed a clear relationship between the structural properties of the materials and the activity for CO2 conversion. The addition of ZrO2 was effective to improve a close interaction between CeO2 and ZrO2 and induced the formation of structural defects that further promoted oxygen transport and facilitated the creation of oxygen vacancies that were critical for CO2 conversion. All samples investigated were found to be effective in converting CO2 into carbon monoxide (CO) at 450 °C, and the addition of ZrO2 was also found to be effective in improving the thermal resistance and stabilising the crystalline structure of the samples especially when the ZrO2 content was > 50 %. When the content of ZrO2 controlled between 50 % and 80 %, the onset temperature for CO2 conversion was found to be 285 °C, which was about 80 °C lower than that required for the sample without ZrO2 modification. Thus, modifying CeO2 by ZrO2 was effective to prevent both the textural and structural alteration of the samples under a high temperature environment as well as cyclic redox operations, resulting in a constant and high degree of CO2 conversion into CO.

Morphology, Microstructure and Improved Mechanical Properties of TiB2/TiB/TiN Reinforced Ti3Al Matrix Composite Coating with ZrO2 Addition

Ti3Al matrix composite coatings were synthesized on a TC4 titanium alloy with Ti, Al and BN mixed powder by in situ laser cladding. Then, the effect of ZrO2 addition to the composite coatings was investigated. The phase composition, microstructure and element distribution of the composite coatings were characterized by scanning electron microscopy, x-ray diffraction and electron probe microanalysis. Results showed that the Ti3Al matrix composite coatings were reinforced by TiB2, TiB and TiN phases. The quality and mechanical properties of the composite coating can be significantly improved with ZrO2 addition under optimum laser power of 1000 W. The microhardness of the composite coatings was 2-3 times higher than that of the substrate, and the wear resistance of the composite coating without and with ZrO2 addition was enhanced by nearly 4 and 7 times compared to the substrate. The better properties of the composite coating with ZrO2 addition were mainly attributed to the formation of a ZrO2 network. The network-like distribution of ZrO2 provided dispersion strengthening and grain refinement effects. This research is expected to provide a new coating material to obtain high-performance Ti3Al matrix composite coating.

Assessment of the Impact of the Addition of Nanoparticles on the Properties of Glass-Ionomer Cements.

The aim of the study was to evaluate the effects of incorporation of Al2O3, ZrO2 and TiO2 nanoparticles into glass–ionomer cements (GICs). Two different GICs were used in the study. Four groups were prepared for each material: the control group (without nanoparticles) and three groups modified by the incorporation of nanoparticles at 2, 5 or 10 wt %, respectively. Cements were mixed and placed in moulds (4 mm × 6 mm); after setting, the samples were stored in saline (one day and one week). Compressive strengths were measured and the morphology of the fractured surfaces was analyzed by scanning electron microscopy. The elements released into the storage solutions were determined by Inductively coupled plasma-optical emission spectrometry (ICP-OES). Addition of nanoparticles was found to alter the appearance of cements as examined by scanning electron microscopy. Compressive strength increased with the addition of ZrO2 and especially TiO2 nanoparticles, whereas the addition of Al2O3 nanoparticles generally weakened the cements. The ion release profile of the modified cements was the same in all cases. The addition of Al2O3, ZrO2 and TiO2 nanoparticles into GICs is beneficial, since it leads to reduction of the microscopic voids in the set cement. Of these, the use of ZrO2 and TiO2 nanoparticles also led to increased compressive strength. Nanoparticles did not release detectable levels of ions (Al, Zr or Ti), which makes them suitable for clinical use.

Structural and Mechanical Properties of Chitosan Doped with Zirconium Oxide

Abstract In this work, chitosan (CTS) powder has been doped with zirconium oxide (ZrO2) at different wt.% in order to improve the mechanical strength of the composites for biomedical applications. The composites have been prepared by ball milling method and the sintering has been done at three temperatures 100°C, 150°C and 180°C for 3 hours in air. The crystalline structure of the composites was confirmed by X-ray diffraction (XRD) pattern and the crystallite size of the composites decreases with increasing the percentage of ZrO2 and sintering temperature. The improvement of mechanical strength of the composites with the addition of ZrO2 in CTS polymer matrix has been investigated using micro-Vickers hardness tester and observed that the hardness of the prepared composite increased to 536 MPa when 90 wt.% CTS doped with 10 wt.% ZrO2 at 180°C of sintering temperature, demonstrating that the composites can be a potential candidate in bone tissue engineering.

Oxidative ammonolysis of 3,4-dimethylpyridine on the vanadium oxide catalysts

Oxidative ammonolysis of 3,4-dimethylpyridine on an individual vanadium oxide (V2O5) catalyst and binary vanadium oxide catalysts, modified by additions of SnO2 and ZrO2, has been studied. A connection between ??- acidity of the methyl groups of the substrate in the gaseous phase and in the chemosorbed state and the sequence of their transformation into a cyano group has been established. It has been shown that nucleophilicity of vanadyl oxygen, calculated by the Density Functional Theory method, increases with V2O5 modification by SnO2 and ZrO2 additions. Herewith, an increasing yield of 3- methyl-4-cyanopyridine and imide of pyridine-3,4-dicarboxylic acid was observed. A proposed mechanism of the imide of pyridine-3,4-dicarboxylic acid formation has been discussed

Wear studies of spark plasma sintered ZrO2 reinforced Ti-6Al-4V alloy

The aim of this paper is to investigate wear and tribological properties of powder metallurgy processed Ti-6Al-4V with additions of ZrO2 to produce Ti-6Al-4V/ZrO2 composites consolidated via spark plasma sintering. The spark plasma sintered compacts were examined using optical microscopy (OM) and scanning electron microscopy (SEM) techniques. Dry sliding wear tests were carried out at 5 N and 10 N using a pin-on-disk tribometer. Optical micrographs showed that additions of ZrO2 to Ti-6Al-4V promoted the formation of agglomerated ZrO2-rich particles in the matrix of Ti-6Al-4V. The friction coefficient values were very similar for all compositions, with values ranging between 0.35 and 0.55, with the lowest COF value recorded for Ti6Al4V/5ZrO2 composite at 10 N applied load. Wear and microhardness results indicate that the hardness and the wear resistance improved with increasing content of ZrO2. The lowest surface degradation was observed for Ti-6Al-4V with 10% ZrO2. The low wear resistance of Ti-6Al-4V in comparison to Ti-6Al-4V/ZrO2 composites can be attributed to the low hardness of this alloy. Adding ZrO2 to Ti-6Al-4V was found to significantly improve the wear and hardness properties of Ti-6Al-4V and may therefore potentially broaden the scope of application and performance of Ti-based materials in critical applications; particularly where wear and friction are critical concerns.

Al–Zr alloys synthesis: characterization of suitable multicomponent low-temperature melts

Al–Zr alloys as an advanced metal matrix composite material start to be attractive for various special applications. The electrochemical preparation of aluminium–zirconium alloy from cryolite melts seemed to be very perspective. Characterization of low-temperature sodium and potassium cryolite-based systems with the different additions of ZrO2 and Al2O3 (both as an electrochemical active compounds) was realized. The electrical conductivity of NaF–AlF3–Al2O3–ZrO2 and KF–AlF3–Al2O3–ZrO2 systems as a function of the temperature was studied. The addition of AlF3 varied from 33mol% to 42mol% in the sodium cryolite system and from 40.0mol% to 45.5mol% in the potassium cryolite system. Alumina and/or zirconia were added in amounts up to 1.2mol% and 2mol%, respectively (sodium system), and up to 2.8mol% and 3mol%, respectively (potassium system). The behavior of the electrical conductivity in the studied systems was described by the regression equations valid in a large temperature and concentration ranges.

Preparation of CaO-MgO-ZrO2 refractory and its desulfurization effect on Ni-based alloy in vacuum induction melting (VIM)

The effect of micromonoclinic ZrO2 addition on properties of CaO-based refractories was investigated in our work. Zero, 5 wt%, 10 wt%, and 15 wt% micromonoclinic ZrO2 powders were added into CaO-MgO (CaO-based) refractories. The obtained results indicated that with the introduction of micromonoclinic ZrO2, the density increased slightly after heated at 1600 °C for 3 h. The results indicated that the density and mechanical properties of the samples were improved after introducing micromonoclinic ZrO2. The hydration resistance of the samples was improved with appropriate proportion of ZrO2. However, excessive ZrO2 damaged the hydration resistance of the samples. The influence of monoclinic ZrO2 on the samples was mainly caused by CaZrO3, the reaction product of CaO and ZrO2. The details of the CaZrO3 effects on the samples were discussed in this paper. Besides, based on the experiment results, CaO-based crucible was prepared and used in desulfurization. The desulfurization effects were compared with desulfurizer: Al. Desulfurizer reduced the content of [O] and [S] in the alloy obviously.

Fabrication and analysis of lightweight magnesia based aggregates containing nano-sized intracrystalline pores

To efficiently reduce heat loss in high-temperature furnaces, the use of a working lining with low thermal conductivity, in lightweight refractories is a significant development. Conventional lightweight refractories focus on the fabrication of Al2O3-based, spinel-based, or Al2O3-spinel based refractories with micro-sized closed pores. In this study, lightweight magnesia-based aggregates with smaller nano-sized pores were fabricated by the decomposition of magnesite by using nano-sized Al2O3 and ZrO2 as additives. The lightweight magnesia containing nano-sized intracrystalline pores (100–300 nm) had a relatively low thermal conductivity of 4.539 W⋅m−1K−1 at 500 °C with a bulk density of 3.37 g/cm3 and a closed porosity of 4.3%. Moreover, the formation mechanism of nano-sized intracrystalline pores was proposed, and the effect of nano-sized additives on the sintering properties was discussed. We concluded that nano-sized Al2O3 and ZrO2 raise the number of nano-sized intracrystalline pores by increasing their migration distance required to separate from the magnesia grains. With the joint addition of nano-sized Al2O3 and ZrO2, the lightweight magnesia possessed the lowest thermal conductivity, as well as excellent strength, owing to the generation of intergranular MgAl2O4 spinel. Furthermore, the nano-sized Al2O3 and ZrO2 also promoted the sintering of magnesia resulting in the formation of cation vacancies (VMg⁎⁎).

Phosphoric acid doped composite proton exchange membrane for hydrogen production in medium-temperature copper chloride electrolysis

A copper chloride (CuCl) electrolyzer that constitutes of composite proton exchange membrane (PEM) that functions at medium-temperature (>100 °C) is beneficial for rapid electrochemical kinetics, and better in handling fuel pollutants. A synthesized polybenzimidazole (PBI) composite membrane from the addition of ZrO2 followed with phosphoric acid (PA) is suggested to overcome the main issues in CuCl electrolysis, including the copper diffusion and proton conductivity. PBI/ZrP properties improved significantly with enhanced proton conductivity (3 fold of pristine PBI, 50% of Nafion 117), superior thermal stability (>600 °C), good mechanical strength (85.17 MPa), reasonable Cu permeability (7.9 × 10−7) and high ionic exchange capacity (3.2 × 10−3 mol g−1). Hydrogen produced at 0.5 A cm−2 (115 °C) for PBI/ZrP and Nafion 117 was 3.27 cm3 min−1 and 1.85 cm3 min−1, respectively. The CuCl electrolyzer efficiency was ranging from 91 to 97%, thus proven that the hybrid PBI/ZrP membrane can be a promising and cheaper alternative to Nafion membrane.

Thermophysical properties of urania-zirconia (U,Zr)O2 mixed oxides by molecular dynamics

Molecular dynamics simulations were used to investigate the thermophysical properties of (U,Zr)O2 between 300 K and 3500 K. For compositions with <25% UO2 the tetragonal phase is stable and beyond 25% the cubic fluorite phase becomes stable for all temperatures. Thermal expansion, heat capacity and thermal conductivity have been predicted. The addition of ZrO2 to UO2 causes a reduction in thermal conductivity however this effect decreases with increased temperature and becomes insignificant beyond 1000 K. Thermal expansion of (U,Zr)O2 mixtures with >25% UO2, which are in the cubic fluorite phase, is similar to that of UO2. A superionic transition is observed in cubic (U,Zr)O2 at temperatures between 1500 K and 3000 K, occurring at progressively lower temperatures with increasing ZrO2 content. The heat capacity of these mixed oxides increases from 80 J/mol.K up to 130 J/mol.K at temperatures relevant to accident conditions, possibly retarding temperature increase in fuels with a significant pellet-clad bonding layer.

An erosion and corrosion study on thermally sprayed WC-Co-Cr powder synergized with Mo2C/Y2O3/ZrO2 feedstock powders

The present study is based on erosion wear analysis of WC-Co-Cr powder thermally sprayed on super-duplex stainless steel (SDSS) 2507. A high-velocity oxy-fuel (HVOF) process was used to deposit the WC-Co-Cr thermal spraying powder. A small weight proportion of Mo2C, Y2O3 and ZrO2 feedstock powders was mechanically blended to WC-Co-Cr thermal spraying powder for analyze the improvement in erosion wear. Erosion wear experiments were conducted using a slurry pot tester at a rotational speed of 600–1500 rev/min for time duration of 90–180 min. Sand was used as the erodent medium; the concentration of solid particles was varied from 30% to 60% (by weight). Present study was extended to analyze the mechanical properties of coatings. Results show that the 3% addition of feedstock powders was beneficial to improve the erosion wear resistance of SDSS-2507. The addition of Y2O3 and Mo2C had improved the erosion wear performance of WC-Co-Cr coating. The addition of Y2O3 provided high erosion wear as compared to Mo2C addition. The addition of ZrO2 was helpful to significantly improve the corrosion resistance of WC-Co-Cr coating whereas it decreases the erosion wear resistance of coating.

Mechanical and tribological characteristics of ZrO2 reinforced Al2014 matrix composites produced via stir casting route

Metal matrix composites reinforced with fillers found many applications in several industries like aerospace and automobile in recent decades. In this current work, Al2014 was chosen as the matrix material and Zirconium Oxide (ZrO2) as reinforcing material. ZrO2 was varied at 2, 4, 6 wt% in Al2014 matrix while magnesium was maintained constant at 1 wt% for all compositions. Magnesium was added to the composite for increasing the wettability. The composites was produced by stir casting process. The dispersion characteristics of the manufactured specimens was studied by Field Emission Scanning Electron Microscope (FESEM) with EDS. The specimens were prepared according to ASTM standards to carry out tests like tensile strength, compressive strength, hardness and impact strength. The tribological properties of the manufactured Al2014 and Al2014 composites specimen were examined using two body wear tests. The mechanical properties and tribological properties of the Al2014 composites increased when the addition of ZrO2 by 6 wt%. The worn surface morphology of the abraded samples was studied by optical microscope which minimum level of damage when ZrO2 was added at 6 wt%.