Addition Of ZrO2 Research Articles

Synergistically enhanced nitrate removal by capacitive deionization with activated carbon/PVDF/polyaniline/ZrO2 composite electrode

• Mixture design to optimize composite electrode toward nitrate removal in CDI cell. • 75.13% increase of Cs and 55.47% reduction in R ct for composite vs. AC electrode. • E3 as optimum electrode with ion electrosorption capacity of 6.01 mg g −1 at 2.0 V. • Maximum specific capacitance of 58.67F g −1 and Rct of 1.26 Ω for E3 electrode. • Highest water recovery of 72.94% and nitrate removal efficiency of 60.01% in the CDI. This work aims to introduce a novel ternary composite electrode to improve the performance of the capacitive deionization process toward nitrate removal from water through enhancing the specific capacitance of the carbon-based electrode. The mixture design methodology was utilized to find the optimum composite electrode containing activated carbon (AC), PVDF, ZrO2, and polyaniline as emeraldine salt (PANi-ES) with the highest specific capacitance. The morphology, specific surface area, functional groups and wettability, electrochemical behavior, specific capacitance, and charge transfer resistance of the electrode were evaluated by field emission scanning electron microscopy, Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, contact angle, cyclic voltammetry, and electrochemical impedance spectroscopy, respectively. The optimum E4 electrode containing 80 wt% AC, 6.0 wt% ZrO 2 , and 6.0 wt% PANi–ES and 8 wt% PVDF was compared to E1 (AC/PVDF), E2 (AC/PVDF/PANi-ES) and E3 (AC/PVDF/ZrO 2 ) electrode. The addition of ZrO 2 into AC as the E3 electrode could attain 19.43% increase in specific capacitance and 34.27 %decrease in charge transfer resistance. In comparison, incorporating both PANi-ES and ZrO 2 into AC led to 75.13% and 51% increase of specific capacitance and wettability, respectively, and 55.47% reduction in charge transfer resistance. This behavior was attributed to the synergistic improvement of specific capacitance by increasing its electrical conductivity and wettability (hydrophilic) and consequently improved the performance of nitrate ion separation by mesoporous structure. Based on the optimum applied voltage of 2.0 V on the E3 electrode, the electrosorption capacity, the maximum nitrate removal efficiency, the water recovery, and specific capacitance were calculated 6.01 mg g −1 , 60.01%, 72.94%, and 58.67F g −1 in the batch mode CDI cell, respectively.

Characteristic of heat transfer nanofluid of Al2O3 improved by ZrO2 addition

Efforts to replace conventional fluids as coolants for heat transfers with new fluids are continuously being made to improve heat transfer efficiency. Nanofluids are currently widely studied around the world as candidates for conventional fluids substitutes. In this research, the synthesis of Al2O3-ZrO2 nanocomposites for heat transfer nanofluid applications was carried out. The synthesis of the nanoparticles was conducted by the hydrothermal method. Here, we used ZrO2 to improve the characteristics of Al2O3. The results of XRD analysis showed that the nanocomposite had an Al2O3 gamma structure. The Al2O3 nanoparticles and Al2O3-ZrO2 nanocomposite have a crystallite size of 7.41 nm and 6.84 nm, respectively. The addition of 0.1 % ZrO2 decreased the crystallite size and BET particle size and increased the zeta potential, hence the stability of the nanofluids. The increase of stability increased the heat transfer coefficient of the Al2O3 nanofluids, making them suitable for heat transfer.

Crystallization, structure, and properties of TiO2-ZrO2 co-doped MgO-B2O3-Al2O3-SiO2 glass-ceramics

TiO2–ZrO2-codoped MgO–B2O3–Al2O3–SiO2 glass-ceramics were prepared using the traditional melting method. The effects of replacing TiO2 with ZrO2 on the glass stability (GS), crystallization behavior, structures, and properties of the obtained samples were studied. Results showed that the addition of ZrO2 increased the GS, which decreased the crystallization ability of the samples. When the heat treatment temperature was increased from 900 °C to 1000 °C, the mullite and quartz phases first precipitated in the glass matrix, and then converted into cordierite. Because of the low solubility of TiO2 and ZrO2 in this glass system, the rutile and zircon phases will precipitate from the parent glasses. Owing to changes in the composition and structure of the samples, the density and Vickers hardness increased, while the coefficient of thermal expansion of the samples first decreased and then increased when TiO2 was replaced with ZrO2.

Effect of diameter and content of zirconium dioxide on the microstructure and mechanical properties of the TC17 titanium alloy repaired by wire arc additive manufacture

Wire arc additive manufacturing (WAAM) has many advantages of high efficiency and low cost to repair blades or blisk made of titanium alloy. In this work, different contents and sizes of ZrO2 particles were added in the single-layer deposition and the multi-layer deposition fabricated by the WAAM technology to investigate the microstructure and mechanical properties of the repaired TC17 titanium alloy. Results show that the content and size of ZrO2 particles have a great influence on the geometry shape and β grain morphology. Especially, the deposition height (dH) increased and the deposition width (dW) decreased with the increased content of 75 µm ZrO2 under the direct current arc. The silicides are promoted to form with the addition of ZrO2, and more silicides tend to precipitate between the heat affected bands (HABands). The addition of ZrO2 can extremely increase the ultimate strength and make the plasticity meet the standard requirements. Especially, the ultimate strength of the multi-layer deposition with 0.5 wt% +50 nm ZrO2 was highest, 1116 MPa, which is 100 MPa higher than that of the deposition without ZrO2 addition. Meanwhile, the strength of the multi-layer deposition with the addition of 1 wt%+ 75 µm ZrO2 have less of an uplifting effect compared with that of 0.5 wt%+ 75 µm ZrO2.

Raw glass-ceramics glazes from SiO2–Al2O3–CaO–MgO–Na2O–K2O system modified by ZrO2 addition – Changes of structure, microstructure and surface properties

In this paper, raw glazes from the SiO2–Al2O3–CaO–MgO–K2O–Na2O system were examined. Zirconium oxide, in five different amounts – 1.5, 3, 6, 12 and 24 wt%, was added to the chosen system and heat treated at 1230 °C, where they were kept for an hour. The addition of zirconium oxide, especially in greater amounts, caused the crystalline phase of zirconium silicate and intact ZrO2 grains to appear. The amounts of these crystalline phases indicate that zirconium cations are present in the amorphous phase. Analysis of structural measurements showed that zirconium ions (Zr4+) have a depolymerizing effect on the glassy matrix of the glazes; however, it does not change subnets of an aluminum-silicon subnetwork. This is a new perspective on the matter, because it confirms that the addition of zirconium oxide causes those ions to be present not only in crystalline phases, but also some Zr4+ cations are located in the aluminosilicate subnetwork (Si–O–Si(Al)), in interstitial spaces, and it interacts only with silicon-oxygen bonds. Measurements of the color in the CIE L*a*b* system of the obtained glazes confirmed that the addition of zirconium oxide results in glaze with significantly higher whiteness (L* parameter increases) and a more monochromatic color (a* and b* parameters tend toward zero). The results of the surface smoothness were also presented, which clearly confirm that the higher content of zirconium crystalline phases results in obtaining a surface with higher roughness.

Dry reforming of methane over Ni-based catalysts: Effect of ZrO2 and MgO addition as support

The increasing content of greenhouse gases (GHG’s) in earth’s atmosphere is the main reason for global warming. Dry reforming of methane (DRM) is an encouraging technique to utilize the two main GHG’s (i.e., CO2 and CH4). Three different Ni based nano-catalysts i.e., Ni/Al2O3, Ni/Al2O3-ZrO2 and Ni/Al2O3-MgO were synthesized by wet-impregnation method and tested for DRM. The prepared catalysts were characterized via BET, XRD, FESEM-EDX, and TEM analysis, to determine the textural properties, phases, morphology, and elemental composition of catalysts. The catalysts were then tested for DRM at low reaction temperature of 650 °C. The Ni/Al2O3-MgO catalyst showed the optimum performance with elevated conversions of CH4 and CO2, followed by Ni/Al2O3 and Ni/Al2O3-ZrO2 catalysts, respectively.

Tribological and Mechanical Behaviour of Hybrid Al 6061 Metal Matrix Composites

Metal matrix composites (MMCs) possess significantly improved properties including high specific strength, specific modulus, damping capacity and good wear resistance compared to unreinforced alloys. The metal matrix choices for Al6061 matrix were silicon carbide (SiC), magnesium oxide (MgO) in constant proportions with either zirconium dioxide (ZrO2) or alumina (Al2O3) as the reinforcements. The stir casted samples were tested for their tensile strength, impact strength and wear. The results confirmed that stir formed Al6061 with Al2O3, MgO, SiC, ZrO2 reinforced composites is clearly superior to base Al6061. It is found that elongation tends to decrease with increasing particles weight percentage, which confirms that alumina and ZrO2 addition increases brittleness. It appears from this study that ultimate tensile strength and yield strength trend to increase with an increase in weight percentage of the reinforcements in the matrix. Impact strength is increased by adding Al2O3 and MgO, SiC, ZrO2.

Enhanced mechanical properties in ceramic multilayer composites through integrating crystallographic texture and second-phase toughening

Inherent brittleness and low mechanical reliability usually inhibit the application of ceramic materials in many structural applications. In this work, we demonstrate that integrating crystallographic texture and second-phase toughening strategies can effectively improve fracture resistance and mechanical reliability in alumina multilayer composites. Composites consisted of equiaxed (1-x)Al2O3-xZrO2 and highly [0001]-textured Al2O3 layers were fabricated, and effects of ZrO2 amount on fracture behavior and mechanical properties of the composites were studied. Increasing ZrO2 amount x results in larger thermal expansion difference between equiaxed and textured layers. The composites with equiaxed layers containing 30 vol% ZrO2 exhibit high apparent fracture toughness Kapt, c ~11.7 MPa·m1/2 and work of fracture γWOF ~1540 J/m2, which correspond respectively to about 260% and 410% enhancements relative to those without ZrO2 addition. Moreover, adding ZrO2 remarkably reduces sensitivity of failure stress to flaw size in the multilayer composites, and the failure stress substantially increases with increasing ZrO2 content. The greatly enhanced mechanical performance achieved here can be mainly attributed to higher magnitude of compressive stresses, more crack bifurcations and longer crack deflection paths within the textured layers. This work can provide important guidelines for developing novel “bio-inspired” materials with improved fracture resistance and flaw tolerance behavior.

Deoxygenation of pyrolysis vapor from palm fruit cake over NiMo/γ-Al2O3 catalyst: Effect of CeO2, TiO2, and ZrO2 additives

Deoxygenation of pyrolysis vapor from palm fruit cake by different catalysts was prior investigated by using Ni/γ-Al2O3, Mo/γ-Al2O3, and NiMo/γ-Al2O3 prepared by wet impregnation method. NiMo/γ-Al2O3 showing the highest degree of deoxygenation (%DOD) activity was subsequently mixed with metal oxides: CeO2, TiO2, and ZrO2. Effects of the catalysts on upgrading of pyrolysis vapor from palm fruit cake at 450°C under N2 atmosphere in a semi-batch process were investigated. The oil products were analyzed for CHNO elements by elemental analyzer, chemical compositions by a gas chromatograph coupled to a mass spectrometer (GC-MS), and higher heating values (HHV) by Dulong's equation. Catalysts have been characterized and discussed related to the product yields and properties. Acidity and acid strength of the catalyst mixture play an important role on the products. NiMo/γ-Al2O3 improved properties of the crude bio-oil by increasing organic phase yield, %DOD, and HHV. Addition of CeO2 to NiMo/γ-Al2O3 reduced phenol compound in the liquid products while addition of TiO2 to NiMo/γ-Al2O3 provided high aromatics and hydrocarbons comparable to those obtained from NiMo/γ-Al2O3/ZrO2. Addition of ZrO2 to NiMo/γ-Al2O3 exhibited the highest organic phase yield (%), %DOD (71%), and HHV (37 MJ/kg).

Effect of ZrB2 and its oxide impurities (ZrO2 and B2O3) on hot-pressed Si3N4 ceramics at low temperature

Based on the previous work on Si3N4-ZrB2, the addition of 2.5 vol.% ZrB2 promoted α- to β-Si3N4 phase transformation, bimodal microstructure, and toughness and strength improvement after hot-pressing at 1500 °C. However, the mechanism needed to be further explored. In the present work, the effect of ZrB2 and its oxide impurities (ZrO2 and B2O3) on phase composition, microstructure and mechanical properties of Si3N4 ceramics with MgO-Yb2O3 additives were studied. Results showed that the addition of B2O3 had no influence on Si3N4 ceramics, whereas the addition of ZrO2 inhibited the α- to β-Si3N4 phase transformation, formed an uniform equiaxed microstructure, and deceased the toughness and strength. The positive effect of oxide impurities can be eliminated. Based on the STEM analysis, the possible reason was that the addition of ZrB2 led to the formation of Si-Mg-O-N-Yb-Zr-B liquid phase, and then promoted α- to β-Si3N4 phase transformation.

Effect of Zirconium Oxide Reinforcement on Microstructural, Electrochemical, and Mechanical Properties of TiNi Alloy Produced via Powder Metallurgy Route

Abstract Equiatomic TiNi alloy composites, reinforced with 0, 5, 10, and 15 vol% ZrO2, were synthesized using conventional sintering approach. Equiatomic TiNi pre-alloyed powder and ZrO2 powder were mixed in planetary ball mill for 6 h followed by cold compaction and pressure-less sintering, respectively. The sintered density was found to vary inversely with the addition of ZrO2 content. The X-ray diffraction (XRD) spectra have shown the formation of multiple-phases which were resulted from the decomposition of the B19′ and B2 phases of the equiatomic TiNi alloy due to the addition of ZrO2 and higher diffusion rate of Ni than that of Ti in the alloy composite. An increase in hardness was noted due to the addition of ZrO2, measured by micro and nanoindentation techniques. Potentiodynamic polarization scan revealed a 10% decrease in the corrosion rate of the composite containing 10 vol% ZrO2. Electrochemical impedance spectroscopy (EIS) results indicated an increase in passive layer resistance (Rcoat) due to the increase in charge transfer resistance (Rct) caused by the reduced leaching of ions from the surface.

Economic and Ultrafast Photocatalytic Degradation of Orange II Using Ceramic Powders

Different percentages of CuO and ZnO were added into a local kaolin ceramic-based powder (DD3) with and without ZrO2. The modified powders were first characterized, then, a test for the photocatalytic degradation of dyes with orange II (OII) was carried out. The DD3 powders that were obtained with the addition of ZrO2, ZnO, and CuO, were prepared by two different methods and have shown a large and very fast photocatalytic activity. Discoloration ratios of about 93.6% and 100% were reached after 15 min and 45 min, for CuO and ZnO respectively. Finally, an alternative photocatalysis mechanism, based purely on chemical reaction processes, is proposed. The photocatalysis results with modified powders are compared with the results obtained with thin films, made with the same materials.

Fabrication and thermal shock behavior of ZrO2 toughened magnesia aggregates

MgO-based refractories have been regarded as ideal linings for various furnaces owing to high refractoriness and excellent corrosion resistance to basic slag. However, thermal shock damage resulting from poor thermal shock resistance (TSR) of magnesia is the common failing. The present work aimed at improving TSR of magnesia aggregates by introducing microscale monoclinic ZrO2. The results showed that the ZrO2 added could increase cation vacancy concentration and inhibit abnormal growth of MgO grains, which therefore enhanced densification of the specimens. However, when the ZrO2 amount exceeded 15 wt%, densification decreased slightly due to agglomeration of ZrO2 and formation of more microcracks at the MgO grain boundaries. With increasing ZrO2 content, although the flexural strength degraded, the fracture toughness increased constantly because of the toughening effects of crack deflection and crack branching. Besides, although the addition of ZrO2 decreased the thermal conductivity, TSR of the specimens was significantly improved with increasing ZrO2 content due to the increase in toughness and decrease in strength, thermal expansion coefficient as well as Young's modulus. After thermal shock tests, 15 wt% ZrO2 containing specimen exhibited the highest TSR, whose residual strength ratio was about triple of that of the pure magnesia specimen. However, further increasing ZrO2 content to 20 wt% reduced the TSR attributing to the spalling of intergranular ZrO2 agglomerations.

Tribological Investigation of Composite MoS2-TiO2-ZrO2 Coating Material by Response Surface Methodology Approach

Abstract Molybdenum disulfide (MoS2) is popularly used in tribological applications because of its excellent lubricating properties. However, its performance needs to be further improved. In the present study, an attempt has been made to improve the wear resistance of pure MoS2 coating by incorporating TiO2 and ZrO2 nanoparticles as a reinforcement material into the MoS2 base matrix. The composite MoS2-TiO2-ZrO2 coating was applied onto substrate surface by the bonding technique. The tribological performance of the coated specimens was evaluated by employing various operating conditions (such as wt% of compounding elements, contact pressure, and sliding speed) using pin-on-disc friction and wear test rig. A statistical model was developed to identify the significant factors affecting the friction coefficient (COF) and wear-rate of the composite coating material. The design of experiment (DOE) was formulated by response surface methodology (RSM) approach to cut down the number of experiments and to develop a mathematical model between the key process parameters such as wt% of compounding elements, contact pressures, and sliding speeds. Analysis of variance (ANOVA) was executed for checking the adequacy of the empirical models developed. It was discovered that the COF and wear-rate of composite MoS2-TiO2-ZrO2 coating significantly affected by the wt% addition of ZrO2. The SEM and optical microscopy analyses of the worn surfaces and transfer films indicated that the tribological properties of composite MoS2-TiO2-ZrO2 coating were significantly improved compared to pure MoS2 coating.

Influence of nucleating agents on crystallization and electrical properties of SiO2–MgO–MgF2–K2O mica glass-ceramics

The effects of adding ZrO2 and TiO2 at the expense of MgF2 on the crystallization, microstructure, mechanical properties, thermal properties and electrical properties of mica glass-ceramics based on the SiO2–MgO–MgF2–K2O system were investigated by the differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), microhardness tester and resistivity tester. The electrical properties were discussed emphatically. The results showed that the additions of ZrO2 and/or TiO2 at the expense of MgF2 effectively increase the viscosity, the glass transition temperatures (Tg) and the crystallization temperatures (Tp) of the glasses. The crystallization activation energy (Ec) of the amorphous glasses varied with the nucleating agents was discussed in depth. It was discovered that the nucleating agents had no effect on the crystal phase type but had a certain effect on the crystallinity and microstructure. Tetrasilicic fluoromica and enstatite were precipitated at different crystallization temperatures. Due to the non-stoichiometric ratio of tetrasilicic fluoromica crystal, the prepared glass-ceramics had high dielectric constant (24.4–34.3) and volume resistivity (>2 × 1011 Ω cm) at 25 °C, and the dielectric loss was almost zero.

Impact of ZrO2 additive on the microstructure, magnetic properties, and temperature dependence of the initial permeability of LiTiZn ferrite ceramics

The effect of the diamagnetic ZrO2 addition on the microstructure and magnetic properties of LiTiZn ferrite ceramics, including the shape and parameters of the temperature dependence of the initial permeability, has been investigated. The defect structure of ferrite ceramic samples is assessed according to our earlier proposed method based on the mathematical treatment of the experimental temperature dependencies of the initial permeability. It was found that the defect structure of ferrite ceramics increased by 350% with an increase in the concentration of the ZrO2 additive in the range of (0–0.5) wt.%. In this case, for the same samples, the increase in the true physical broadening of diffraction peaks is only 20%, and the coercive force by 50%. Simultaneously, the maximum of the experimental temperature dependence of the initial permeability dropped by 45%. The microstructure of all samples is characterized with a similar average grain size according to the SEM data. However, samples with 0.5 wt.% of ZrO2 are characterized by the formation of conglomerates. A linear relationship was obtained between the defect structure and the width of the diffraction peaks, which indicates that this parameter is related to the elastic stress of ferrite ceramics. These results suggest that the high sensitive proposed method can be recommended for impurity and defect monitoring of soft ferrite products.

Performance of Al2O3-CBN materials and perspective of using hyperspectral imaging during cutting tests

The performance of cutting tool materials (CTMs) influences the quality and lifetime of parts produced with their help. Unexpected fracturing or other failures of the tools lead to defects of parts that exaggerate materials fatigue and fracture processes. For the purpose of Industry 4 and future generations of factories it is important to enable in-situ monitoring of cutting processes while hyperspectral imaging can serve as a powerful tool. Cubic boron nitride (cBN) has extreme hardness and can provide improved wear resistance if mixed with other CTMs. Besides, such materials can be used without cooling liquids that helps to mitigate workplace health risks. The aim of the current work was to understand how well current hyperspectral imaging technologies can track the changes in performance of CTMs with addition of cBN. The paper presents the results of multiple in-situ (obtained during cutting with real lathe) and static (before or after cutting) tests performed with hyperspectral camera. The wear rate of CTMs and roughness of workpieces were measured with the help of scanning electron microscope and 3D optical profiler respectively. The effect of cBN content and effect of TiN or ZrO2 additives on performance of alumina-based CTMs produced by spark plasma sintering technique is presented.

Effect of rotary swaging and subsequent annealing on microstructure and mechanical properties of W-1.5ZrO2 alloys

W-1.5ZrO2 alloy bars with two diameters, named as D9 and D5, were prepared by liquid phase method and rotary swaging method. The effects of swaging and annealing on the microstructure and mechanical properties of tungsten alloys were investigated. Under the same swaging ratio, the compressive strength of D5 tungsten alloy and D9 tungsten alloy is 23.27% and 22.37% higty her than that of pure W, respectively. After multi-pass swaging, the diameter of tungsten alloy decreased from 9 mm to 5 mm, and the hardness and compressive strength increased by 14.6% and 21.93%, respectively. After multi-pass rotary swaging, the diameter of tungsten alloy is reduced from 9 mm to 5 mm, and the hardness and compressive strength are increased by 14.6% and 21.93% respectively. The fracture mode has gradually changed from intergranular fracture to trans-granular fracture. Therefore, the strength of tungsten alloy can be improved by adding zirconia and proper swaging process. With the increase of annealing temperature or time, recrystallization and grain growth will be caused. The addition of ZrO2 can delay the recrystallization of tungsten alloy during annealing, and inhibit grain growth. When the annealing temperature is lower than 1200 °C, the compressive strength of tungsten alloy remains unchanged, while the failure strain increases. After annealing at 1500 °C, the strength and failure strain of tungsten alloy decreased by 18.9% and 35.7% respectively. In order to obtain excellent strength and toughness, annealing at 1100–1200 °C for 1 h can be chosen for W-1.5ZrO2 alloy.

Enhanced performance of low-carbon MgO–C refractories with nano-sized ZrO2–Al2O3 composite powder

Low-carbon MgO–C refractories are facing great challenges with severe thermal shock and slag corrosion in service. Here, a new approach, based on the incorporation of nano-sized ZrO2–Al2O3 composite powder, is proposed to enhance the thermal shock resistance and slag resistance of such refractories in this work. The results showed that addition of ZrO2–Al2O3 composite powder was helpful for improving their comprehensive performances. Particularly, the thermal shock resistance of the specimen containing 0.5 wt% composite powder was enhanced significantly which was related to the transformation toughening of zirconia and in-situ formation of more spinel phases in the matrix; also, the slag resistance of the corresponding specimen was significantly improved, which was attributed to the optimization of pore structure and formation of much thicker MgO dense layer.

Improvement in Hardness and Wear Behaviour of Iron-Based Mn-Cu-Sn Matrix for Sintered Diamond Tools by Dispersion Strengthening.

The work presents the possibility of fabricating materials for use as a matrix in sintered metallic-diamond tools with increased mechanical properties and abrasion wear resistance. In this study, the effect of micro-sized SiC, Al2O3, and ZrO2 additives on the wear behaviour of dispersion-strengthened metal-matrix composites was investigated. The development of metal-matrix composites (based on Fe–Mn–Cu–Sn–C) reinforced with micro-sized particles is a new approach to the substitution of critical raw materials commonly used for the matrix in sintered diamond-impregnated tools used for the machining of abrasive stone and concrete. The composites were prepared using spark plasma sintering (SPS). Apparent density, microstructural features, phase composition, Young’s modulus, hardness, and abrasion wear resistance were determined. An increase in the hardness and wear resistance of the dispersion-strengthened composites as compared to the base material (Fe–Mn–Cu–Sn–C) and the commercial alloy Co-20% WC provides metallic-diamond tools with high-performance properties.