Addition Of ZrO2 Research Articles

Research on the interfacial structure and property improvement of the Cfiber/2Si-B-3C-N ceramic matrix composite

A mixture of the mechanically alloyed 2Si-B-3C-N powder and short carbon fiber was hot pressed at 1800 °C for 30 mins in nitrogen. Careful investigation to the prepared Cfiber/2Si-B-3C-N ceramic matrix composite revealed that the composite was very difficult to be densified. Heterogeneous nucleation, abnormal grain growth and severe interface reaction occurred on the fiber surface or between the fiber and the ceramic matrix, leading to a small density and weak mechanical properties of the composite. For the prepared composite without any additive, the relative density, flexural strength, elastic modulus and fracture toughness is 71.7%, 64.6 MPa, 14.7 GPa and 1.47 MPa·m1/2, respectively. The average size of the SiC grains close to and far away from the carbon fiber is 249.10 nm and 50.45 nm, respectively. However, with the addition of ZrO2 (7.5 mol%), the above mentioned phenomenons are changed noticeably, and those properties are significantly increased to 88.5%, 112.4 MPa, 111.1 GPa and 2.94 MPa·m1/2, respectively. At the same time, the SiC grains close to or far away from the carbon fiber almost have the same average size of about 448.21 nm, and almost no interface reaction occurs. It shows that the addition of ZrO2 not only facilitates the sintering and densification process, but also depresses the interface reaction, promotes the homogeneous nucleation and grain growth, and hence significantly improves the mechanical properties of the Cfiber/2Si-B-3C-N composite. This interesting finding is favorable for the preparation of carbon fiber reinforced ceramic matrix composite, which requires both a large relative density and well controlled interface reaction.

New Observations on High-Speed Machining of Hardened AISI 4340 Steel Using Alumina-Based Ceramic Tools

High-speed machining (HSM) is used in industry to improve the productivity and quality of the cutting operations. In this investigation, pure alumina ceramics with the addition of ZrO2, and mixed alumina (Al2O3 + TiC) tools were used in the dry hard turning of AISI 4340 (52 HRC) at different high cutting speeds of 150, 250, 700 and 1000 m/min. It was observed that at cutting speeds of 150 and 250 m/min, pure alumina ceramic tools had better wear resistance than mixed alumina ones. However, upon increasing the cutting speed from 700 to 1000 m/min, mixed alumina ceramic tools outperformed pure ceramic ones. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to investigate the worn cutting edges and analyze the obtained results. It was found that the tribo-films formed at the cutting zone during machining affected the wear resistances of the tools and influenced the coefficient of friction at the tool-chip interface. These observations were confirmed by the chip compression ratio results at different cutting conditions. Raising cutting speed to 1000 m/min corresponded to a remarkable decrease in cutting force components in the dry hard turning of AISI 4340 steel.

Preparation and characterization of Mo/ZrO2–Y2O3 composites

Mo/ZrO2–Y2O3 composites were successfully prepared through high-energy ball milling and powder metallurgy technique. The morphologies of the composite powders, the microstructures and properties of the sintered compacts and rotary swaged compacts were studied. The results show that ZrO2 addition refined the grains of composite powders and Mo alloys by promoting grains nucleation and inhibiting grains growth. Tetragonal zirconia (t-ZrO2) was completely stabilized at room temperatures by Y2O3 and evenly distributed in the molybdenum matrix. Moreover, ZrO2 was bonded with Mo matrix by an interfacial bonding zone. All above microstructures improve the mechanical properties and recrystallization temperature of the composites. The added values of yield strength, tensile strength and elongation of the doped Mo alloys after annealing all exceed 30% at room temperature, compared with pure Mo. ZrO2 particles make an effect on dispersion strengthening and improving recrystallization temperature by hindering dislocations movement.

Effects of ZrO2 and Y2O3 on physical and mechanical properties of ceramic bond and ceramic CBN composites

In order to optimize the structure performances of ceramic cubic boron nitride (CBN) grinding wheels, the effects of ZrO2 and Y2O3 addition on the physical and mechanical properties of ceramic bond and ceramic CBN composites were systematically investigated. The basic ceramic bond was composed of B2O3, Al2O3, SiO2, Li2O and Na2O. The additions of ZrO2 and Y2O3 had a certain effect on refractoriness, liquidity, flexural strength of ceramic bonds. The experimental results demonstrated that in the ceramic bonds, both ZrO2 and Y2O3 could promote the formation of glass grid, while the ceramic bond strength would further increase. In addition, the new phase of YBO3 appeared in the ceramic bond, due to the filling of Y2O3. When the contents of ZrO2 and Y2O3 were 4 wt% respectively, the strength of the ceramic bond was highest, increasing by 23% (16.1 Mpa) compared to the basic ceramic bond. The last point required to be pointed out was that the phase transformation toughening of ZrO2 cannot be achieved and it was limited by low temperature sintering.

On the Yttrium Tantalate – Zirconia phase diagram

The phase diagram for the YTaO4-ZrO2 quasi-binary has been determined up to 1600 °C. There are three distinct compositional regimes: an extensive YTaO4 solid solution, an extensive ZrO2 solid solution and a two-phase intermediate region. The addition of ZrO2 to YTaO4 decreases the M–T transition temperature almost linearly from 1426 °C to approximately 450 °C at the solubility limit (∼28 mol% ZrO2), and then remains constant until the ZrO2 solid solution phase boundary is reached. Within the intermediate region, there exists an extensive two-phase tetragonal (T + t) phase field above the M–T transformation temperature. The transformation exhibits no hysteresis on heating and cooling but nonetheless there is a distribution with temperature in the mass fraction of the monoclinic and tetragonal phases so no unique transformation temperature can be identified. No other high temperature phases were observed but it is suggested that a higher temperature solid solution phase is likely above 1700 °C, based on the similarity in crystallographic relationship between the two tetragonal solid solution structures.

An effective and magnetic Fe2O3-ZrO2 catalyst for phenol degradation under neutral pH in the heterogeneous Fenton-like reaction

Abstract A novel Fe2O3-ZrO2 catalyst was prepared by the sol-gel method, and investigated for phenol degradation in the Fenton-like reaction under neutral pH condition. The ZrO2 addition increased the surface areas of the catalyst. Scanning electron microscopy (SEM) showed that ZrO2 nano-particle dispersed on the surface of Fe2O3. X-ray photoelectron spectroscopy (XPS) indicated that the Fe2+ amount increased with the increase of the Zr content on the surface. The Fe2O3-ZrO2 catalyst produced hydroxyl radicals (OH ) and superoxide radicals (O2 −/HO2 ), and exhibited good catalytic performance in the reaction. Total phenol conversion and 56% TOC removal were achieved after 210 min under neutral pH at 60 °C in the heterogeneous Fenton-like reaction. In addition, the prepared Fe2O3-ZrO2 catalyst had good magnetism.

Improvement of energy storage density with trace amounts of ZrO2 additives fabricated by wet-chemical method

Lead-free (1-x)[0.6SrTiO3-0.4Na0.5Bi0.5TiO3]-xZrO2 ceramics (STNBT-xZr) were synthesized in single perovskite phase. The average grain size decreased from 3.2 μm (x = 0.1 mol%) to 1.6 μm (x = 0.6 mol%) related to the addition of ZrO2 powders prepared by microwave hydrothermal method. With the increasing of ZrO2 content, the permittivity decreased gradually, and the breakdown strength (Eb) was remarkably improved due to composition induced disturbing of long range ferroelectric order. The increase of Eb led to the improvement of the recoverable energy storage density (Wre) from 1.80 J/cm3 (x = 0.1 mol%) to 2.84 J/cm3 (x = 0.5 mol%). However, when Zr4+ content was more than 0.5 mol%, the Wre decreased from 2.84 J/cm3 to 2.26 J/cm3 (x = 0.6 mol%) due to the reduction of the maximum polarization. The best energy storage properties were achieved in STNBT-xZr ceramic with Zr4+ content of x = 0.5 mol%, which exhibited the Wre of 2.77–2.84 J/cm3 in the range of 4–40 Hz, revealing an excellent frequency stability. All these results demonstrate the STNBT-xZr (x = 0.5 mol%) ceramics are quite promising for frequency-stable energy storage applications.

Redox-Driven Restructuring of FeMnZr-Oxygen Carriers Enhances the Purity and Yield of H2 in a Chemical Looping Process

Chemical looping-based approaches allow for the production of high purity hydrogen from methane with an inherent separation of the coproduced carbon dioxide. In such a process, first methane is oxidized using lattice oxygen from a solid oxygen carrier. In the second half-cycle, the reduced oxygen carrier is reoxidized with steam to yield hydrogen. In this work, we report on the development of an iron-based oxygen carrier with an excellent redox stability and probe the synergistic effect of adding Mn2O3 and ZrO2, leading to an enhancement of the reactivity of iron oxide with methane and increasing the hydrogen yield over multiple redox cycles. The promoting effects of Mn2O3 and ZrO2 in the oxygen carrier were elucidated by combining TPR, STEM-EDX, reactivity tests, and conductivity measurements complemented by SIMS analysis. The addition of ZrO2 promoted the oxidation reactivity of the material, whereas the addition of Mn2O3 accelerated the reduction of iron oxide. Conductivity measurements revealed that t...

The Difference of Impact Strength in Acrylic Resin Self-Cured with the Addition of Zirconium Dioxide (ZrO2) Nanoparticles

<p><strong><em>Background:</em></strong><em> Self-cured acrylic resin is a material used for repairing broken and fractured dentures. Zirconium dioxide (ZrO2) is a reinforcing material that is being developed as an additive to the acrylic resin. <strong>Objective:</strong> to determine the effect of zirconium dioxide (ZrO<sub>2</sub>) addition on self-cured acrylic resin on impact strength. <strong>Material and Methods:</strong> This study was a true experimental laboratory study with the design of a post-test only control group design, using 24 pieces of self-cured acrylic resin measuring 65 x 10 x 2.5 mm divided into 4 groups with and without zirconium addition dioxide (ZrO<sub>2</sub>) nanoparticles. Zirconium dioxide (ZrO<sub>2</sub>) nanoparticles were silanized first by mixing the silane coupling agent. Furthermore, the impact strength was tested on the plate. The data obtained were analyzed using the One Way ANOVA test. <strong>Results:</strong> there were significant differences in the impact strength between the groups with a significance value of 0,000 (p <0.05). <strong>Conclusion:</strong> there was a difference in the increase of impact strength in acrylic resin self-cured with the addition of ZrO<sub>2</sub> nanoparticles concentrations of 3%, 5%, and 7%.</em></p><p><em><br /></em></p><p><strong><em>Key words:</em></strong><em> Self cured acrylic resin, zirconium dioxide, impact strength</em><em></em></p><p><strong><em> </em></strong></p><strong><em>Correspondence </em></strong><em>: Widaningsih, Department of Prosthodonti, Faculty of Dentistry, Hang Tuah University, Arif Rahman Hakim 150, Sukolilo, Surabaya, Phone 0818312757, Email: </em><a href="mailto:widaningsih2008@yahoo.com"><em>widaningsih2008@yahoo.com</em></a>

Extraction of Scandium and Zirconium from Their Oxides during the Electrolysis of Oxide–Fluoride Melts

The main features of scandium and zirconium extraction from their oxides to aluminum during the aluminothermic and electrolytic preparation of Al–Sc and Al–Zr alloys and master alloys in the KF–AlF3, NaF–AlF3, and KF–NaF–AlF3 oxide–fluoride melts with Sc2O3 and ZrO2 additives are studied. The influence of the melt composition and temperature, the synthesis time, the contents of oxides Sc2O3 and ZrO2 in the melts, the mechanical stirring of aluminum, and the cathodic current density on the contents of scandium and zirconium in aluminum and on their extraction from the oxides is determined. The average values of scandium and zirconium extraction are 20–75 and 40–100%, respectively, depending on the synthesis parameters. The electrolytic decomposition of the oxides in the KF–AlF3, NaF–AlF3, and KF–NaF–AlF3 melts results in the enhancement of scandium and zirconium extraction to aluminum. The parameters of the preparation of Al–Sc and Al–Zr alloys and master alloys with the scandium content to 10 wt % and zirconium content to 15 wt % during the electrolysis of oxide–fluoride melts are chosen as a result of the results obtained.

Effect of nanostructured zirconium dioxide incorporation in an experimental adhesive resin.

The aim of this study was to evaluate the influence of nanostructured zirconium dioxide incorporation in an experimental adhesive resin. ZrO2 particles were characterized by X-ray diffraction (XRD), micro-Raman spectroscopy and Brunauer-Emmett-Teller (B.E.T). Experimental adhesive resins were formulated with 0, 0.5, 1, 4.8, and 9.1% ZrO2 in weight. The adhesives were evaluated based on degree of conversion (DC), radiopacity, softening in solvent and microtensile bond strength (μTBS) 24h and after 1year of aging. Mineral deposition at the hybrid layer was assessed with micro-Raman spectroscopy at the baseline and after 14days. XRD showed monoclinic and tetragonal phases of ZrO2.particles. B.E.T data revealed a surface area of 37.41m2/g, and typical chemical groups were shown on the Raman spectra. The addition of ZrO2 did not influence the radiopacity. The addition of 4.8% and 9.1wt.% ZrO2 showed higher initial hardness with increased softening in solvent (P < 0.05) and promoted mineral deposition at the dentin interface. DC was significantly increased in the group with 1% ZrO2 (P < 0.05). The μTBS test showed difference on the group with 9.1wt.% of ZrO2, with a significant reduction after aging. The incorporation of ZrO2 promoted mineral deposition on the adhesive interface and the addition of 1wt.% caused a significant increase on the DC without compromising the other physicochemical characteristics, which may prove promising for the development of new dental adhesive systems. The mineral deposition on the hybrid layer can result in a longer stability of the adhesive, thus delaying the hydrolytic degradation.

Sensor Properties of Nanostructured Systems Based on Indium Oxide with Co3O4 or ZrO2 Additives

The effect of Co3O4 and ZrO2 additives on the sensory response of In2O3-based nanostructured composites to H2 and CO is studied. It is shown that the addition of small amounts of Co3O4 or ZrO2 to In2O3 leads to a sharp increase in the sensory response to hydrogen. The maximum sensory response of the ZrO2−In2O3 composite to 1100 ppm of hydrogen increases from 80 to 270 as the ZrO2 content changes 0 to 20 wt %. The response to CO varies only slightly. For Co3O4−In2O3 composites, the maximum response to H2 and CO increases with the Co3O4 content within 0−10 wt %. A further increase in the Co3O4 content leads to a significant decrease in the response, with composites containing ∼60 wt % Co3O4 being characterized by a very low efficiency. In the Co3O4−In2O3 system with a content of up to 60 wt % Co3O4, electronic conduction is realized, which changes to hole conduction at Co3O4 within 80−100 wt %. In the ZrO2−In2O3 system, electric current flows through In2O3 nanocrystals, i.e., n-type conduction takes place. Possible reasons for the observed effects are discussed.

Effect of nano ZrO2 on nano zinc phosphating of mild steel

A low temperature zinc phosphating processing accelerated by an eco friendly nano ZrO2 and nano ZnO is developed. The effects of nano ZrO2 on the nano zinc phosphating of mild steel were studied by Scanning Electron Microscopy (SEM),X-ray Diffraction(XRD), Transmission Electron Microscopy(TEM) and Electrochemical measurements. Results showed that the addition of nano ZrO2 of varying concentration from 0.5 to 3 g/L in the phosphating bath has larger influence on the phosphate coating weight and the corrosion resistance of the coatings. Nano ZrO2 was adsorbed on the coating, increases the number of nucleation sites, refined the grain size and accelerated the precipitation of phosphates. Addition of nano ZrO2 in the phosphating bath decreased the corrosion current density and increased the corrosion resistance of the coatings. Better corrosion resistance was observed for coatings derived from phosphating baths containing 1.0 to 1.5g/L of nano ZrO2.

Corrosion, adhesion and erosion study of MZ and ML system using thermal plasma

Mullite processed through thermal plasma has been identified as promising material in ceramic industry for thermal barrier coating (TBC) applications. Addition of ZrO2 as impurities reduces the fracture toughness property of mullite coatings. In the current study, effort has been taken to compare the performance of La2O3 as an equivalent material to ZrO2. Here MZ (Mullite-ZrO2) and ML composites (Mullite-La2O3) have been prepared in different weight proportions of 10%, 20% and 30%. The MZ and ML composites are ball milled for 2 hr and sprayed over AISI 1045 steel specimen at 15 cm and 20 cm spray distance using 15kW thermal plasma torch. The MZ and ML coated samples were studied for SEM, XRD, adhesion test, roughness, wear, sliding test and coating thickness. Though the ML material has not been tested for exact application, but the study reveals that La2O3 can be used as cost effective material for TBC applications.

Corrosion, adhesion and erosion study of MZ and ML system using thermal plasma

Mullite processed through thermal plasma has been identified as promising material in ceramic industry for thermal barrier coating (TBC) applications. Addition of ZrO2 as impurities reduces the fracture toughness property of mullite coatings. In the current study, effort has been taken to compare the performance of La2O3 as an equivalent material to ZrO2. Here MZ (Mullite-ZrO2) and ML composites (Mullite-La2O3) have been prepared in different weight proportions of 10%, 20% and 30%. The MZ and ML composites are ball milled for 2 hr and sprayed over AISI 1045 steel specimen at 15 cm and 20 cm spray distance using 15kW thermal plasma torch. The MZ and ML coated samples were studied for SEM, XRD, adhesion test, roughness, wear, sliding test and coating thickness. Though the ML material has not been tested for exact application, but the study reveals that La2O3 can be used as cost effective material for TBC applications.

Advanced technology for Al-Zr alloy synthesis: Electrochemical investigation of suitable low-melting electrolytes

Aluminium-zirconium alloys start to be attractive in various fields such as military, aerospace industry, nuclear reactions or atomic energy. The investigation of low-temperature sodium and potassium cryolite based melts with the different additions of ZrO2 was realized in order to develop the scientific basis of the technology for aluminium-zirconium alloy synthesis. The electrical conductivity of NaF-AlF3-ZrO2 and KF-AlF3-ZrO2 systems as a function of temperature was studied by a tube-type cell with fixed distance between the electrodes, applying ac-techniques with a sine wave signal with small amplitude in the high frequency range. The addition of the aluminium fluoride varied in the range (33–38) mol % in sodium cryolite melts (molar ratio MR = n(Na(K)F)/n(AlF3) = 2.0–1.6) and from 40 mol % to 45.5 mol % (MR = 1.5–1.2) in the potassium cryolite system. Zirconia was added into the basic two-component melts in amounts of (1–4) wt % for sodium system and (1.7–5.2) wt % for potassium system. All measured data were evaluated by the regression analysis (the least square method) for calculation of the electrical conductivities in both investigated melts.

Effect of Nano-ZrO2 on the Properties of Al-Al2O3 Nanocomposites Prepared by Mechanical Alloying

In the present work, mechanical alloying was used to prepare Al-20wt.% Al2O3 metal-matrix nanocomposites having up to 4wt.% ZrO2 at the expense of Al2O3. The powders were milled for different time intervals. To characterize the powders after milling, x-ray diffraction and transmission electron microscopy were used to identify the phase composition, crystallite size and morphology. In order to study the sinterability, the milled powders were cold pressed and sintered in argon atmosphere at different firing temperatures up to 470 °C for 1 h. The relative density and apparent porosity of the sintered composites were determined according to Archimedes principle. Moreover, the microstructure was examined by a scanning electron microscope attached with an energy dispersive spectrometer (EDS). Microhardness and AC conductivity of sintered composites were also measured. The results pointed out that the increasing of milling time is responsible for uniform distribution of Al2O3-ZrO2 particles in the Al matrix as well as remarkable increases in relative density, microhardness and AC conductivity of the sintered specimens. Also, the relative density was affected considerably by the increasing of sintering temperature. Moreover, increasing of ZrO2 content led to a significant decrease in the crystal size of the milled powders and increase in the microhardness of the sintered compacts. No changes were observed on the conductivity after addition of ZrO2.

Effect of AlN and ZrO2 on the microstructure and property of the 2Si-B-3C-N ceramic

The mechanically-alloyed amorphous 2Si-B-3C-N powder was hot pressed at 1900°C for 30mins in argon. A small amount (5mol.%) of AlN and ZrO2 was added to investigate their effect on the sintering process, microstructure and properties of the 2Si-B-3C-N ceramic. XRD, SEM, TEM and property testing results show that, the addition of AlN or ZrO2 promotes the sintering process of the 2Si-B-3C-N composite powder, accelerates the crystallization and grain growth, and improves the density and mechanical properties of the prepared ceramic. Under an axial pressure of 80MPa and a gas pressure of 8bar, significant densification occurs to the 2Si-B-3C-N ceramic free from any additives just when the temperature is higher than 1830°C. The addition of AlN and ZrO2 decreases this critical temperature to about 1760°C and 1730°C, respectively. As a result, for the prepared bulk ceramic, the average grain size is increased from 80nm to 200nm and 250nm, the relative density is enhanced from 88.7% to 96.9% and 97.7%, and the bending strength is improved from 331MPa to 416MPa and 575MPa, respectively. Careful investigation reveals that in the prepared bulk ceramic, AlN forms solid solution with SiC, and ZrO2 exists in the form of t-ZrO2 and m-ZrO2 nanocrystals. Thus, the addition of AlN and ZrO2 may facilitate the atomic diffusion, the grain growth and the densification process of the 2Si-B-3C-N ceramic in difficult ways.

Tribological and corrosion behavior of (100-x)(Fe70Ni30)-(x)ZrO2 composites synthesized by powder metallurgy

The aim of the present work is focused on the effect of ZrO2 addition on the tribological and electrochemical behavior of (Fe,Ni) matrix based composites. (100-x)(Fe70Ni30)-(x)ZrO2 composites were prepared using powder metallurgy route, where x is 2.5, 5, 10 and 15 wt%. The formation of taenite γ-(Fe,Ni) and kamacite α-(Fe,Ni) phases in the matrix was evident from x-ray diffraction (XRD). ZrO2 particles have not participated in any intermediate phase formation and found to be dispersed in matrix as a unreacted phase. Corrosion test of prepared composites was conducted in 3.5% NaCl aqueous solution (simulated sea water) at room temperature. The pin on disc tribological tests has shown a strong impact of reinforcing hard ZrO2 particles in improving the wear resistance whereas the presence of both taenite and ZrO2 phases has contributed in improving the corrosion resistance. Increasing the fraction of ZrO2 reinforcement particles up to 10 wt% improves both the wear resistance and corrosion resistance. Beyond this limit, property degradation was evident. It is due to the high contact of ceramic to ceramic particles and weak metal/reinforcement interface at higher reinforcement content, resulting in brittle behavior. Electrochemical impedance spectroscopy (EIS) studies indicate the adsorption/diffusion phenomenon at the interfaces which is responsible for localized corrosion. Microstructural and surface roughness test before and after the tests were performed using scanning electron microscope (SEM) and profilometer studies.

Fast setting tricalcium silicate/magnesium phosphate premixed cement for root canal filling

MTA-based root-end filling is a promising therapeutic approach for root repair, however, difficult handling characteristics, presence of toxic elements in the material composition and long setting time are main drawbacks for clinical applications. The purpose of this study was to develop a novel fast setting silicate based premixed cement for endodontic use. The premixed cement contained tricalcium silicate (C3S) as the main constituent for hydration, magnesium phosphate cement (MPC) as setting accelerators and glycerol as water-miscible liquid. The physicochemical properties and antibacterial property of the novel cements were evaluated. Moreover, biocompatible zirconium oxide (ZrO2) was chosen as radiopacifying agent added into the premixed cement. The radiopacity, physicochemical properties, antibacterial property and cytotoxicity of the radiopaque premixed calcium silicate based cements were evaluated. The setting time of the premixed MPC/C3S cements could be modulated within the range from 70min to 205min by adjusting the content of MPC. Meanwhile, the premixed MPC/C3S cement displayed good flowability and injectability when the amount of MPC less than 20%. The addition of ZrO2 provided the premixed MPC/C3S cement with excellent radiopacity while had no significant effects on the setting time, flowability, film thickness, injectability and washout resistance. Moreover, the premixed cement with or without ZrO2 had good antibacterial property and cytotoxicity. Our results indicated that the premixed MPC/C3S/ZrO2 cement could be considered as a promising candidate for application in endodontics owing to its desirable physicochemical properties, antibacterial activity and cytocompatibility, especially relatively short setting time and good sealing ability.