Addition Of ZrO2 Research Articles

Titanium carbide – Titanium boride composites by self propagating high temperature synthesis approach: Influence of zirconia additives on the mechanical properties

Abstract This work presents the fabrication of high-dense titanium carbide – titanium boride (TiC-TiB2) composites by self-propagating high temperature synthesis (SHS) under-load methodology. The influence of particle size of boron carbide (B4C) and the amount of titanium (Ti) on the TiC-TiB2 composites properties is explored. The structural features and crystalline structures of the prepared composites were systematically characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The influence of zirconia (ZrO2) additives on the mechanical properties of prepared composites is explored and explained. The obtained results reveal that ZrO2 additives have a significant influence on the mechanical properties of TiC-TiB2 composites. An addition of 20 wt% ZrO2 results in a maximum enhancement of 1805 HV in comparison to 1683 HV for as-produced TiC-TiB2 composite. Detailed thermodynamic study of the effect of ZrO2 on the combustion process is also presented. Our results provide novel insights into the fabrication of TiC-TiB2 – based composites, establishing for the first time the influence of zirconia additives on the mechanical properties of the resulting composites, opening new opportunities to develop advanced composites for structural applications.

Vpliv dodatka ZrO2 na izdelavo ZrO2/Mg kompozitov z vrtilno-tornim postopkom

Vpliv dodatka ZrO2 na izdelavo ZrO2/Mg kompozitov z vrtilno-tornim postopkom

A Novel Method for Adding Graphite Flakes to Al2O3–ZrO2‐Graphite Composites and Performance Testing

A novel method to produce graphite flakes was invented, and this method is good for homogeneous of graphite among the Al2O3‐ZrO2‐Graphite composite powder. Graphite ball, alumina ball, and alumina powder are put into planetary muller together, and the graphite flakes are produced by shear forces between the surface of graphite and alumina ball during the ball mill process. Al2O3‐χwt%ZrO2‐3wt%Graphite (A‐χZ‐3Gr, χ = 5, 10, 15, 20) composites powder are developed by this new method and then are sintered using microwave at a temperature of 1500 °C for 30 min in argon atmosphere. Actually 3wt%Graphite (Gr) is fully capable of forming a lubricating film on the rubbing surface of A‐χZ‐3Gr composites to ensure a low friction coefficient. On the other hand, the ZrO2 addition is good for the mechanical properties. The effect of ZrO2 addition on the relative density, hardness, fracture toughness and bending strength of the various A‐χZ‐3Gr composites are investigated. The performance of A‐χZ‐3Gr composites has been greatly improved as compared with Al2O3‐3 wt% Graphite sintered under the same condition. The A‐10Z‐3Gr composite exhibited excellent performance such as its relative density, hardness, fracture toughness, bending strength, friction coefficient, and wear rate are 95.4%, 323.7Mpa, 5.8Mpa · m1/2, 9.3Gpa, 0.31 and 5.19 × 10−6mm3 Nm−1, respectively.

Sol-Gel synthesis of high-temperature aluminosilicate glass-ceramics and composite materials on its basis

Powders of strontium aluminosilicate glass-ceramics were synthesized by a sol-gel method. Composite materials based on them with the addition of industrial powders α-Si3N4, β-Si3N4, Y2O3, ZrO2 and HfO2 were obtained by the method of spark plasma sintering. It was found that reinforcement with silicon nitride leads to an increase in K1C of glass-ceramics by more than 2 times. The temperature of sintering and the properties of composite materials (CM) are complexly dependent on the nature of the refractory oxide. Maximum strength is typical for CM containing Y2O3 additive, and maximum microhardness is for material with HfO2 additive. Modification by refractory oxides leads to an improvement in oxidation resistance of composite materials.

Effect of ZrO2 Addition on Mechanical Properties and Microstructure of Al-9Zn-6Mg-3Si Matrix Composites Manufactured by Squeeze Casting

Steel is used because of its high strength and toughness, but it has high density, therefore lighter material with comparable toughness is developed. One alternative is aluminum matrix composite with zirconia (ZrO2) as the reinforcement with high fracture toughness. Al-9Zn-6Mg-3Si (wt. %) composites were developed with addition of 2.5, 5, and 7.5 vol. % ZrO2 through squeeze casting. To improve toughness, the composite was solution treated at 450 °C for 1 h, then aged at 200 °C for 1 h. Materials characterization included Optical Emission Spectroscopy (OES), Rockwell B hardness testing, impact testing, fractography analysis, microstructure analysis using Optical microscope (OM) and Scanning Electron Microscope (SEM) / Energy Dispersive X-Ray Spectroscopy (EDS), as well as X-Ray Fluorescence (XRF). The results showed that the more ZrO2 particles, the higher porosity and the lower the hardness and the impact values, both in as-cast condition and after ageing at 200 °C at 1 h.

Promotional effect of acidic oxide on catalytic activity and N2 selectivity over CeO2 for selective catalytic reduction of NOx by NH3

The CeO2, CeO2‐ZrO2 and CeO2‐WO3 catalysts were prepared by hydrothermal method and used to the selective catalytic reduction of NOx by NH3. The addition of ZrO2 or WO3 into CeO2 was favorable for pore structure, and then improved the number of active sites. Besides, the introduction of ZrO2 into CeO2 could improve the Lewis acid sites while WO3 could contribute to the generation of Brønsted and Lewis acid sites, which could improve the catalytic performance and N2 selectivity. The CeO2‐WO3 catalyst exhibited optimal catalytic activity with above 90% NOx conversion performance at 220–425 °C and approximately 100% N2 selectivity at 150–425 °C.

Studies of Ceria and Zirconia Promotion of Nickel Catalyst for Carbon Dioxide Reforming of Methane

The CO2 reforming reactions of methane were carried out using three types of Ni/δ-Al2O3s and the effects of the addition of CeO2 were examined. In this study, the addition of a high weight percentage of CeO2 focused on reducing the amount of deposited carbon. It was revealed that a high Al2O3 surface area was necessary for the effective reduction of the deposited carbon by the addition of 50% CeO2 with the lowest conversion decrease. The addition of CeO2 and ZrO2 (Ni/Al2O3(A)-CeO2(45)-ZrO2(5)) further decreased the deposited carbon to 0.14 mmol per 1 mol of produced CO at 1073 K.

Highly Selective Syngas/H2 Production via Partial Oxidation of CH4 Using (Ni, Co and Ni–Co)/ZrO2–Al2O3 Catalysts: Influence of Calcination Temperature

In this study, Ni, Co and Ni–Co catalysts supported on binary oxide ZrO2–Al2O3 were synthesized by sol-gel method and characterized by means of various analytical techniques such as XRD, BET, TPR, TPD, TGA, SEM, and TEM. This catalytic system was then tested for syngas respective H2 production via partial oxidation of methane at 700 °C and 800 °C. The influence of calcination temperatures was studied and their impact on catalytic activity and stability was evaluated. It was observed that increasing the calcination temperature from 550 °C to 800 °C and addition of ZrO2 to Al2O3 enhances Ni metal-support interaction. This increases the catalytic activity and sintering resistance. Furthermore, ZrO2 provides higher oxygen storage capacity and stronger Lewis basicity which contributed to coke suppression, eventually leading to a more stable catalyst. It was also observed that, contrary to bimetallic catalysts, monometallic catalysts exhibit higher activity with higher calcination temperature. At the same time, Co and Ni–Co-based catalysts exhibit higher activity than Ni-based catalysts which was not expected. The Co-based catalyst calcined at 800 °C demonstrated excellent stability over 24 h on stream. In general, all catalysts demonstrated high CH4 conversion and exceptionally high selectivity to H2 (~98%) at 700 °C.

Synthesis and characterization of ZnZr composites for the photocatalytic degradation of phenolic molecules: addition effect of ZrO2 over hydrozincite Zn5(OH)6(CO3)2

AbstractBACKGROUNDThe composite materials ZrO2/Zn5(OH)6(CO3)2 were prepared in only one step by chemical co‐precipitation and thermal hydrolysis of urea. ZrO2 was added at 5, 8 and 10 mol%. The samples were dried at 80 °C and characterized by adsorption–desorption of N2 isotherms, X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, and diffuse reflectance (DRS), UV–visible, Fourier‐transform infrared (FTIR) and X‐ray photoelectron (XPS) spectroscopies. The materials were assessed in the photodegradation of phenol and polychlorinated phenolic molecules under UV‐light irradiation. The possible mechanism was discussed from studies that corroborated or discarded the formation of the species •OH, •O2− and h+.RESULTSThe addition of ZrO2 to Zn5(OH)6(CO3)2 resulted in a composite material with high photoactivity. The material containing 8 mol% of ZrO2 (ZnZr‐8.0%) was the sample with the best percentages of photodegradation and mineralization. The photodegradation enhancement was achieved partly by an increment in the specific surface area and principally due to localized states originating in the composite interphase which improved charge transfer. XPS study revealed that the ZrO2 addition increases the oxygen vacancies which enhanced the organic molecule photodegradation via direct hole attack.CONCLUSIONThe ZnZr composite system constitutes an excellent alternative for the photodegradation of persistent organic pollutants due to the low cost, high stability and null toxicity of the support Zn5(OH)6(CO3)2. © 2019 Society of Chemical Industry

Effect of different nanoparticles on microstructure, wetting and joint strength of Al–12Si–20Cu braze filler

The effect of nanoparticle additives (La2O3, SiC, and ZrO2) on microstructure and brazing characteristics of Al–12Si–20Cu alloy produced by induction melting was studied. The morphology and composition of the samples was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) analysis. The melting point of the fillers was determined by differential thermal analysis (DTA). Filler wettability was studied in terms of spread ratio (SR) on Al 3003 substrate. The joint strength was assessed by tensile shear study in brazed lap-joints of Al 3003 sheets. The results demonstrated that addition of La2O3 in Al–12Si–20Cu showed best wetting (79.6%) and melting (531.2 °C), while the addition of SiC alloy showed moderate tensile shear strength (79.1 MPa) and lowest wettability (76.34%) among Al–12Si–20Cu–La2O3 and Al–12Si–20Cu–ZrO2 and Al–12Si–20Cu–La2O3 SiC composites. The addition of ZrO2 in Al–12Si–20Cu alloy showed moderate wetting (78.2%) and lowest tensile strength (78.3 MPa) compared to Al–12Si–20Cu–La2O3 and Al–12Si–20Cu–SiC. The mechanism behind the microstructural modification of Al–12Si–20Cu alloy in the presence of nanoparticle additives has also been discussed.

Influence of ZrO2 Nanoparticles on the Microstructural Development of Cement Mortars with Limestone Aggregates

In this research, the effect of the addition of zirconium oxide-synthesized nanoparticles on the microstructural development and the physical–mechanical properties of cement mortars with limestone aggregates was studied. Zirconia nanoparticles were synthesized using the co-precipitation method. According to XRD analysis, a mixture of tetragonal (t) and monoclinic (m) zirconia phases was obtained, with average crystallite sizes around 15.18 and 17.79 nm, respectively. Based on the ASTM standards, a mixture design was obtained for a coating mortar with a final sand/cement ratio of 1:2.78 and a water/cement ratio of 0.58. Control mortars and mortars with ZrO2 additions were analyzed for two stages of curing of the mortar—7 and 28 days. According to SEM analysis, mortars with ZrO2 revealed a microstructure with a high compaction degree and an increase in compressive strength of 9% on the control mortars. Due to the aggregates’ characteristics, adherence with the cement paste in the interface zone was increased. It is suggested that the reinforcing effect of ZrO2 on the mortars was caused by the effect of nucleation sites in the main phase C–S–H and the inhibition of the growth of large CH crystals, and the filler effect generated by the nanometric size of the particles. This produced a greater compaction volume, suggesting that faults are probably originated in the aggregates.

Metal-oxide promoted Ni/Al2O3 as CO2 methanation micro-size catalysts

The Power-to-Gas concept has the challenge to convert the excess of renewable electricity to synthetic natural gas, composed mainly by methane, through CO2 methanation. The superior heat transfer capacity of micro-structured reactors offers a suitable alternative for an efficient control of the reaction temperature. In the present work, the strategy of adding large amount of metal oxide promoters (15 wt.%) to nickel supported on micro-size catalysts (dp = 400–500 μm) is presented. The addition of CeO2, La2O3, Sm2O3, Y2O3 and ZrO2 was clearly beneficial, as the corresponding metal-oxide promoted catalysts exhibited higher catalytic performance than Ni/Al2O3 and the commercial reference Meth® 134 (T = 200–300 °C, P = 5 bar·g). This increase of catalytic activity is attributed to the higher amount of CO2 adsorbed on the catalyst. Among the selected promoters, La2O3 showed the highest catalytic activity (XCO2=+20% at 300 °C) due to the enhancement of nickel reducibility, nickel dispersion and the presence of moderate basic sites. In addition, Ni-La2O3/Al2O3 was stable for one week, while the unpromoted catalyst exhibited a slight decline in its activity. Accordingly, the technical catalyst proposed in this study could be used directly in compact reactors for CO2 methanation with much higher activity than the commercial reference.

Micro hardness and corrosion properties of A390 alloy + x vol.% zirconium dioxide (ZrO<SUB align="right">2) composites processed by P/M method

A390+X vol.% ZrO2 (X = 5, 10, 15) composites have been fabricated through P/M technique. The mixed aluminium alloy and zirconium oxide powders were cold compacted at 200 MPa and sintered at 580°C for 3 h. The influence of ZrO2 reinforcement on microstructure, physical, and electrochemical behaviour of fabricated composites were examined. The results convey that the composites have relative density of 99%. Potentio dynamic polarisation studies on A390 and A390+Xvol.% ZrO2 composites in 3.5 wt.% of NaCl solution revealed that the addition of ZrO2 in Al alloy shifts the corrosion potentials towards positive direction. The increase of ZrO2 content in A390 alloy increases the corrosion current density due to the expansion in particle-matrix interface area. The research goal is to develop a new metal matrix composite material, by powder metallurgy (P/M) technique and experimentally investigate the various mechanical, physical properties and corrosion study, for ensuring that the developed material could be used in pistons.

The effect of nano-zirconia on the morphology and mechanical properties of PVDF/PAN membrane as separators in super capacitors

The PVDF/PAN/ZrO2 (zirconia) composite fibrous membranes were fabricated by electrospinning. The effects of ZrO2 content on solution properties, mechanical properties and crystallisation behaviours as well as related morphology were systematically evaluated. The scanning electron microscopy (SEM) was used to investigate the effect of ZrO2 content on the morphology of PVDF/PAN/ZrO2 composite fibrous membranes, which showed that the diameter is only 0.8 μm when the ZrO2 is 0.4%. It could be attributed to the enhancement of solution conductivity by ZrO2 addition. Nitrogen adsorption based on Brunauer-Emmett-Teller (BET) principle was employed to measure the specific surface area, which indicated that the specific surface area increased about 1.8 times for composite membranes compared to the PVDF/PAN membrane when the ZrO2 content was 0.4%. The tensile strength of fibrous membranes increased from 2.74 of pure PVDF/PAN to 5.11 MPa of PVDF/PAN/ZrO2 when the ZrO2 content was 0.4%. The differential scanning calorimetry (DSC) results showed that the crystallinity and orientation enhanced with increasing of ZrO2, which was beneficial to improve the tensile strength. The Tg and Tc shifted to high temperature with ZrO2 increases, which demonstrated that ZrO2 promoted the heterogeneous nucleation and formed perfect crystal structure.

Properties of nisin incorporated ZrO2/poly (vinyl alcohol)-wheat gluten antimicrobial barrier films

ABSTRACTThe properties of manufactured nisin-ZrO2/poly (vinyl alcohol)-wheat gluten (ZPWG) films were characterized. The formation of hydrogen bonds among the PVA, WG, and ZrO2 units were detected and caused a decrease in the film crystallinity. Also, the degradation rate was increased with WG content. As expected, the addition of WG and ZrO2 influenced the light transmission, tensile properties, gas permeability and water vapor permeability of the films. Nisin-loaded films presented a low initial burst release of the antimicrobial agent, followed by a gradual release. The initial diffusion of nisin (Mt/M∞<2/3) from the ZPWG film was formulated by the Fickian diffusion equation, showing a linear relationship (R2 > 0.998) between Mt/M∞ and t1/2, and the diffusion coefficient D increased with increasing WG content. Antimicrobial activity testing of nisin-ZPWG films with 40 wt% WG showed excellent inhibitory activity against Staphylococcus aureus, indicating its potential as a new active food packaging material.

Effect of ZrO2 addition on densification and properties of Spark plasma sintered Ti6Al4V-Ni

Abstract This study investigates the effect of ZrO2 addition on Ti6Al4V-Ni fabricated using spark plasma sintering. The influence of ZrO2 content on the densification, microstructure and micro-hardness properties of the composites were examined. The SPS process parameters adopted for the sintering of the composites are sintering temperature of 1000 °C, holding time 10 min, heating rate 100 °C/min and applied pressure 50 MPa. Samples were characterized by SEM, and XRD. Relative density and hardness of the composite were also examined. The result revealed that adopted mixing and sintering process resulted in an even dispersion of Ni and ZrO2 particles in the Ti6Al4V matrix with the evolution of Nickel oxide phase. The densification behaviour of the composite showed three distinct densification stages relating to initial particle rearrangement, plastic deformation at powder contact point and mass transport respectively. The addition of ZrO2 resulted in an enhancement of the composite hardness but decreased the density.

Effect of Addition Of Zirconium Oxide Nanoparticles on Flexural Strength and Porosity of Heat Cure Acrylic Resin

Heat cure denture base is the most commonly used material for fabrication of removable prosthesis to the present day. However difficulties persist in fabrication of satisfactory prosthesis due to poor mechanical properties which have resulted in frequent repairs in dental practice. The present study is aimed to investigate the effect of Zirconium oxide nanoparticles (ZrO2NPs) on flexural strength and porosity of denture base and its correlation. X-ray diffraction (XRD) was used to check the purity of NPs. NPs was dispersed at 1%, 3%and 5% by weight to the monomer of methyl methacrylate with aid of probe sonicator. In addition, Scanning Electron Microscope (SEM) was used to observe agglomeration of particles within the acrylic. The results revealed significant flexural strength difference (p&lt;0.05) between each concentration of ZrO2NPs. The analysis showed 17% and 11% reduction for 1% and 3% ZrO2NPs respectively while 5% caused a drastic reduction by 32% in reference to control. In regards to porosity, the results present no statistically significant difference among the concentrations in contrast to control. Pearson correlation showed strong and a negative relation (-0.83) between flexural strength and porosity. However, the results was not statistically significant (p=0.369). Within the limitations of this study, it can be concluded that the addition of ZrO2 caused reduction in flexural strength for all concentrations added. While it caused non-significant effect on porosity of acrylic. Considering the negative effect it had no mechanical strength it won't be considered a suitable additive to enhance the properties of PMMA.

Sintering behavior and properties of lithium stabilized sodium β'' - alumina ceramics with YSZ addition

In this study, investigations of sintering behavior and properties were performed on lithium-stabilized Na-β''-alumina (LiSBA) ceramics with and without 15 wt% 8 mol% Y2O3 stabilized ZrO2 (8YSZ) addition synthesized by solid phase reaction. Changes of phase composition, relative density, and grain size in the ceramics sintered at different temperature were analyzed. It was shown that phase transformation in sintering ceramics was controlled by relationship between the Na2O evaporation and Li+ ions stabilization, while microstructure evolution was controlled by pore-boundary interaction. LiSBA with YSZ addition (Zr-LiSBA) showed more significant variation of β'' phase fractions, slower grain growth and faster densification with increasing sintering temperature, which were caused by enhanced Na2O evaporation and gas transport by oxygen ion conductor ZrO2 as well as the drag effect by second phase particles of YSZ in Zr-LiSBA ceramics. Zr-LiSBA specimens sintered at optimized condition achieved higher Vickers microhardness and intermediate Na+ ion conductivity.

Preparation of ZrO2 fiber modified Al2O3 membrane supports with enhanced strength and permeability

In this paper, Al2O3 membrane support with both enhanced permeability and strength was fabricated by introducing zirconia fiber (ZrO2(f)). Effects of the ZrO2(f) content and sintering temperature on the open porosity, shrinkage rate, microstructure, water permeance, bending strength and pore size of the support were investigated. Results reveal that apart from fiber reinforcement, ZrO2(f) was found to promote open porosity and permeability by changing pore morphology and reducing flow resistance. However, it damages the porous structure if the sintering temperature is excessive. Compared with the un-added sample, the bending strength and water permeance of the support with a ZrO2(f) addition of 4 wt% sintered at 1550 °C increased by 261% and 52%, respectively. The modified support meets the requirement for more demanding operation conditions and may achieve the objects of miniaturizing and lightening the final products.

Effects of ZrO2 Addition on Mechanical Strength and Thermal Shock Resistance of Cordierite-Mullite Ceramics

Cordierite composed of an alumina-silica-magnesia compound has a low coefficient of thermal expansion(CTE) and excellent thermal shock resistance. It also has a low dielectric constant and high electrical insulation. However, due to low mechanical strength, it is limited for use in a ceramic heater. In this study, ZrO2 is added to an 80 wt% cordierite-20 wt% mullite composition, and the effect of ZrO2 addition on the mechanical strength and thermal shock resistance is investigated. With an increasing addition of ZrO2, cordierite-mullite formed ZrO2, ZrSiO4 and spinel phases. With sintering conducted at 1400 °C with the addition of 5 wt% ZrO2 to 80 wt% cordierite-20 wt% mullite, the most dense microstructure forms along with an excellent mechanical strength with a 3-point flexural strength of 238MPa. When this composition is quenched in water at ΔT = 400 °C, the 3-point flexural strength is maintained. Moreover, when this composition is cooled from 800 °C to air, the 3-point flexural strength is maintained even after 100 cycles. In addition, the CTE is measured as 3.00 × 10−6·K−1 at 1000 °C. Therefore, 80 wt% cordierite-20 wt% mullite with 5 wt% ZrO2 is considered to be appropriate as material for a ceramic heater.