ZrO2 Composites Research Articles

Aero acoustic levitation to unveil the solidification of complex oxides: Case study of the system Al2O3–ZrO2

Binary or multi-component phase mixtures are of particular technical importance. Despite the wide field of application of Al2O3 and ZrO2 composites, the literature reveals contradictions about the liquidus region. Containerless processing avoids typical problems of conventional techniques like melt contamination or lack of suitable container materials. Composition ranging from 0–80 mol% ZrO2 were melted and solidified in an aero acoustic levitator. A high-speed camera recorded the crystallization, allowing a direct correlation with the observed microstructures. Due to homogeneous nucleation, all samples exhibited significant undercooling before crystallization. The nucleation temperature of the different compositions roughly followed the slope of the liquidus line. Undercooling, solidification kinetics, and local reheating played a considerable role in microstructure formation. A lamellae eutectic microstructure was created over a large compositional range from 36–48 mol% ZrO2. On the hypoeutectic side, the effect was attributed to solidification within the coupled zone. However, hypereutectic samples also exhibit a zirconia-rich eutectic as well. We assume impaired ZrO2 nucleation or growth favors alumina precipitation from the melt. Aero acoustic levitation proved to be an excellent technique for studying complex high melting oxide systems, enabling a better understanding of their crystallization process.

Influence of the Change of Phase Composition of (1 - x)ZrO2-xAl2O3 Ceramics on the Resistance to Hydrogen Embrittlement.

The article describes the influence of the change in the phase composition of ceramics on the stability of the crystal structure and retention of thermo-physical parameters during hydrogenation of the surface layer in the proton irradiation process. The selection of irradiation conditions allows modeling the degradation processes of ceramics associated with gas swelling during hydrogenation, as well as revealing the patterns of the effect of phase composition on embrittlement, de-strengthening, and structural degradation resistance. In the course of the conducted studies, dose-dependencies of irradiation-induced structural changes and consecutive accumulation of radiation-induced damage in ceramics as a result of hydrogenation of the damaged near-surface layer were established. It was found that the maximum structural changes are observed at doses above 1015 protons/cm2. Dependencies of the change in the degree of structural order as a function of the dose of accumulated damage and the concentration of accumulated protons were obtained. It was established that the variation of the ceramics phase composition due to the formation of solid solutions of ZrO2/Al2O3 and ZrO2/Al2O3/AlZr3 type leads to an enhancement of resistance to swelling by 3-5 times in comparison with monoclinic ZrO2 ceramics. The general analysis of the variation of strength and thermo-physical parameters of ceramics as a function of irradiation fluence for ceramics with different phase compositions showed a direct dependence of the decrease in hardness, resistance to cracking, and thermal conductivity on the concentration of deformation structural distortions caused by irradiation.

Study on Mechanical Behaviour of Al-15Si-10Zn/x ZrO2 Composites Synthesized by Stir Cast Method

In this research, the microstructure and mechanical properties of Al-15Si-10Zn-xZrO2 (x = 5, 7 and 10 wt.%) composites synthesized by the stir-casting process have been investigated. The matrix and composite samples were characterized using an X-ray diffraction test (XRD) and their microstructures were studied using optical microscopy and scanning electron microscopy (SEM). The microstructure of different phases was analyzed using energy-dispersive spectroscopy (EDS). The microstructure of the Al-15Si-10Zn/ZrO2 composites consisted of coarse primary Si, needlelike eutectic Si, and Zn-rich phases, with ZrO2 reinforcement particles distributed homogeneously in the composites. The micro-hardness and tensile properties of the matrix and composites were determined at room temperature. The results show significant improvements in the micro-hardness and tensile strength of the composites compared to the matrix alloy. The micro-hardness of the stir-cast composites increased by 24%, 44%, and 58% in the 5, 7, and 10 wt% ZrO2 reinforcement composites, respectively. The ultimate tensile strength (UTS) of the 5, 7, and 10 wt% ZrO2 composites increased by 17%, 30%, and 44%, respectively, compared to the matrix alloy. The increased content of ZrO2 resulted in an increase in hardness, ultimate tensile and yield strengths and a decrease in ductility.

Hardness prediction in the upsetting process of Al%ZrO2—an approach to machine learning using regression and classification models

The current study focuses on the prediction of metal hardness distribution in upsetting tests for different compositions of ZrO2 embedded with an aluminum matrix using machine learning algorithms and finite element (FE) analysis. The mass fraction of the ZrO2 particles varied from 4% to 8%, and three sets of solid cylindrical rods with Al4%ZrO2, Al6%ZrO2, and Al8%ZrO2 were prepared using the stir casting method. The upsetting process was simulated, and an equation for predicting hardness was developed from the equivalent strain distributions. Artificial neural networks (ANNs), multilinear regression (MLR) along with equations developed from FE analysis were used to train the model for regression analysis, considering the principal stresses, friction factor, anisotropy ratio, effective strain, and hoop strain as input and the magnitude of hardness as output parameters. Regression analysis reveals that ANN (tri-layer network), XGBoost, and MLR algorithms are the best suitable for the given data sets with a root mean square ( R2) greater than 0.95. XGBoost, ANN (narrow), and SVM are linear and are the most recommendable classifier algorithms for the current investigation. Hardness data from ring compression tests were used to validate the results obtained from the trained models with the test results.

An Insight into Synergistic Metal-Oxide Interaction in CO2 Hydrogenation to Methanol over Cu/ZnO/ZrO2

The metal-oxide interaction is of significance to the construction of active sites for Cu-catalyzed CO2 hydrogenation to methanol. This study examines the effect of ZnO and ZrO2 composition on the Cu/ZnO/ZrO2 catalyst structure and surface properties to further tune the catalytic activity for methanol synthesis. The ZnO/ZrO2 ratio can impact the CuZn alloy formation from strong Cu-ZnO interactions and the surface basic sites for CO2 adsorption at the Cu-ZrO2 interface. The proportional correlation of the CuZn alloy content and CO2 desorption amount with the space-time yield (STY) of methanol reveals a synergistic interaction between Cu and oxides (ZnO and ZrO2) that enhances methanol synthesis. The optimized Cu/ZnO/ZrO2 catalyst exhibits higher STY relative to the traditional Cu/ZnO/Al2O3 catalyst. The obtained results presented herein can provide insight into the catalyst design for methanol synthesis from CO2.

Efficiency Dependence of Radiation-Assisted Ceramic Synthesis Based on Metal Oxides and Fluorides on Initial Powder Particle Sizes

The study is devoted to investigating the efficiency dependence of radiation-assisted ceramic synthesis based on metal oxides and fluorides on initial powder particle sizes. The synthesis was performed for 30 series of ceramic samples, including MgO, Al2O3, ZnO, ZrO2, MgF2, and complex compositions: cerium-activated yttrium-aluminum garnet (Y3Al5O12), spinel AlMgO4, and tungstate MgWO4. The synthesis efficiency was evaluated on the mixture weight magnitude losses, morphology, and relative weight of the obtained ceramic samples. Based on the analysis of the synthesis results and measuring the particle distribution spectra of the initial materials, the criteria for selecting the initial materials were established, and possible explanations for the correlation between synthesis efficiency and the initial materials morphology were proposed.

Interaction of SiC with Al2O3−(t + m)ZrO2(Y2O3) Oxide Composition

We employed contact alloying in the range 1000–1860°С to study the reaction specifics between SiC and Al2O3−(t + m)ZrO2(Y2O3) oxide composition. Real-time experiments with photographic recording of the changing size and shape of the Al2O3−(t + m)ZrO2(Y2O3) sample on a SiC ceramic substrate showed that Al2O3−(t + m)ZrO2(Y2O3) compositions react with the silicon carbide substrate in the range 1720–1860°С to melt and penetrate into (impregnate) the substrate. X-ray powder diffraction patterns were measured for samples taken from the contact area of the oxide composition with SiC directly on the substrate and in a chipped-off 1-mm-deep near-surface layer. ZrС, Al2Y4O9, and Al3.21Si0.47 were formed in the contact area via redox reactions involving oxide melt, in addition to 6H-SiC, Si and Al2O3, t-ZrO2 phases, which are the initial components of the substrate and oxide composition, respectively.

Photocatalytic activities of CTAB assisted ZrO2, V2O5, and ZrO2-V2O5 composite by precipitation process and their studies on structural, morphological and optical properties

Nanocrystalline core/shell structures of cetytrimethylammonium bromide (CTAB)-assisted ZrO2, V2O5, and ZrO2-V2O5 composite was successfully prepared by co-precipitation method calcined at 500 °C. CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite were characterized by different techniques such as, X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Brunauer-Emmett-Teller (BET), Ultra-Violet (UV) and Photoluminescence (PL). The formation of ZrO2, V2O5, and ZrO2-V2O5 composite material has been confirmed by XRD studies. Surface morphology with grain size of CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite was determined by SEM and TEM studies. EDX analysis confirms the presence of compositional elements of ZrO2-V2O5 composites in the lattice such as zirconium, vanadium and oxygen. Optical studies reveal a strong absorption and emission peaks were presented in the UV and visible regions and it useful for optoelectronic device applications. In comparison, ZrO2, V2O5, and ZrO2-V2O5 composite exhibited the higher band gap energies with a significant blue-shift and enhanced UV light absorption compared to bulk counterparts. As-prepared photocatalysts, CTAB-assisted ZrO2, V2O5, and ZrO2-V2O5 composite showed strong photocatalytic activity towards the degradation of Rhodamine B (RhB) dye under UV light irradiation, which can facilitate the efficient separation and migration of photo generated electron-hole pairs. Among result, the ZrO2-V2O5 composite exhibited the synergistic enhanced photocatalytic performance and also the possible photocatalytic mechanism was discussed in detail.

Vacuum annealing effects on the microstructure and properties of HfO2-based bilayer antireflective coatings by magnetron sputtering

Hafnia (HfO2) retains thermal stability, mechanical resilience, and chemical resistivity, which makes it feasible in various high-tech applications in optics and integrated circuit technology. This work presents the effects of thermal annealing on the microstructure, optical performance, and wettability of HfO2/Al2O3 and HfO2/ZrO2 bilayer thin films prepared by magnetron sputtering. The films were deposited on silicon (Si) and glass substrates and then annealed at a certain temperature (300–500 °C) in the ambient vacuum condition for 5hrs. XRD results of as-deposited and annealed films revealed the polycrystalline nature of the monoclinic phase. The core level orbitals of Hf 4f, Zr 3d, and Al 2p spectra showed the formation of stoichiometric compositions of HfO2, ZrO2, and Al2O3 films and exhibited a slight shift in binding energy after annealing. The AFM and SEM analysis were utilized to inspect the roughness and surface morphology and correlated with the change in hydrophobicity to the self-cleaning nature of the prepared bilayer coatings. The observed upsurge in refractive indexes of the coatings is allied to the packing density that causes lattice contraction and enhances the attraction between dipoles. The negligible effect of negative temperature on the antireflection efficiency makes it suitable for future applications in optoelectronic, photovoltaic devices operated in a cold or humid environment.

CO2 methanation over Ni supported on Carbon–ZrO2: An optimization of the composite composition

Currently, the most common catalysts for CO2 methanation reaction are based on Ni supported on metal oxides. However, such catalysts require high operation temperatures and present stability issues, which have been tackled by the use of expensive metal oxides such as CeO2 or ZrO2.In this study, the decrease in the amount of ZrO2 in ZrO2-based catalysts was addressed through the preparation of composites of ZrO2 and carbon materials (activated carbon (AC) and carbon nanotubes (CNTs)). The optimization of the carbon:ZrO2 ratio demonstrated an optimal value of 50:50 in the case of AC:ZrO2, and 70:30 for CNT:ZrO2. With this composite composition, the possibility of enhancing the performance of the catalyst by functionalizing the carbon material was evaluated, and it was demonstrated that reduced AC (AC-R) with increased Lewis basic sites showed the best performance for AC-based composites, achieving a CO2 conversion of 79 % and CH4 selectivity of 98.9 % at 400 °C, whereas the catalysts supported on the pristine CNT:ZrO2 composite presented the highest CO2 conversion of 82.1 % and CH4 selectivity of 99.3 % at 400 °C.Notably, promotion with Fe was studied in the best performing support (CNT:ZrO2 (70:30) and it was shown that it enabled an improvement in terms of CO2 conversion and optimal temperature, achieving a CO2 conversion of 85 % and CH4 selectivity of 99.5 % at a lower temperature of 370 °C. This catalyst demonstrated to be highly stable for 70 h of time on stream with no apparent modifications on its chemical composition or microstructure.This work demonstrates that combining the properties of carbon materials and ZrO2 can be an interesting approach to obtain high performing catalysts for CO2 methanation.

Synthesis and Rapid Sintering of Ultra Fine TiB2-ZrO2 Composite

TiB2 is considered candidate materials for ultra-high temperature ceramics and cutting tools because of its a high thermal conductivity, a low coefficient of thermal expansion, a high hardness and high melting temperature. Despite these attractive properties, TiB2 applications are limited because it has a low fracture toughness below the brittle-ductile transition temperature. To improve on its mechanical properties, the approach universally utilized has been to add secondary materials to form a composite and to fabricate an ultra - fine material. A dense ultra - fine TiB2- ZrO2 composite was rapidly sintered using pulsed high current activated heating (PHCAH) methods within 3 min in one step from the mechanically synthesized the powders of TiB2 and ZrO2 . Consolidation was reached using an effective combination of mechanical pressure and the pulsed high current. A highly dense TiB2-ZrO2 material with relative density of 97.2% was made by the simultaneous application of 75 MPa pressure and a pulsed 2500 A current. The grain sizes of TiB2 and ZrO2 in the composite were 135 nm and 84 nm, respectively. The fracture toughness and hardness of the TiB2 -ZrO2 composite were 11.2 MPa.m1/2 and 957 kg/mm2 , respectively. The fracture toughness of the TiB2 -ZrO2 composite was three times higher than that of monolithic TiB2 .

Fabrication of the novel hybridized AZ31B Mg/CeO2+ZrO2 composites via multiple pass friction stir processing

The mixture of the rare-earth CeO2 and ZrO2 particulates was used for fabricating the hybridized AZ31BMg/(CeO2+ZrO2)p composites by utilizing friction stir processing with a multiple-tool pass strategy. The structure, mechanical properties (tensile strength and hardness), tribological performances (wear properties) and corrosion behaviours of the hybrid composites were examined. The findings reveal the elimination of tunnel-like defects and clustering of the CeO2+ZrO2 particles in the composite after the multiple passes of the tool due to the successive mechanical stirring-assisted material flow. The rise in the tool passes reduced the mean grain sizes (7.91–3.02 μm), the particle sizes (5.47–2.28 μm), the average friction coefficient (0.45–0.18) and the specific wear rate (4.26 × 10−5–2.17 × 10−5 mm3/Nm) of the composite. The tensile strength (172–239 MPa), and the corrosion performance of the hybrid composite were also improved via the multiple tool pass strategy. Multiple tool pass is thus recommended for the fabrication of Mg-based hybrid composites.

Fabrication and characterization of ZrO2 reinforced Fe-20Cr alloy composites

The reinforcement effects of the ZrO2 and the wear and mechanical behaviour of (Fe,Cr)-based alloy composites were investigated. The (100−x) (Fe80Cr20) -(x) ZrO2 composites were fabricated via powder metallurgy. The iron-chromium and ZrO2 powders were efficiently milled and mixed in ball mill. In the Fe80Cr20 alloy, the effect was investigated by changing the ZrO2 composition by 5%, 10%, and 15%. The blended powder mixture was cold compacted and sintered at 1030 °C. Scanning electron microscopy (SEM), elemental mapping, and x-ray diffraction techniques were utilized to assess the microstructural properties of the sintered composites. In addition, the mechanical properties such as hardness, flexural strength, and porosity were examined with variations in ZrO2 composites. The dry sliding wear tests with various normal loads and a constant sliding distance were used to find the composite’s wear behaviour. The composite containing 10% ZrO2 has shown the maximum flexural strength with 1470 MPa, and hardness 359.8 HV10 respectively, compared to 5% ZrO2 and 15% ZrO2. With a concentration of 10 wt.% ZrO2, the wear resistance is found to be significantly enhanced, while after 10 wt.% ZrO2, its properties deteriorate. In addition to having improved interfacial bonding, lower porosity, and microstructure uniformity, Fe80Cr20 (Fe-20 Cr) −10 wt% ZrO2 composites exhibit superior mechanical properties compared to other materials.

Improving the wear resistance and mechanical properties of hybridized AZ80 Mg/CeO2+ZrO2 surface composite by friction stir processing: Effect of pin geometry

Geometrically modified pins were utilized for the development of the hybrid AZ80 Mg/CeO2+ZrO2 composite by using the friction stir processing method. The local shear punching strength, structure, hardness, and wear of the hybrid AZ80 Mg/CeO2+ZrO2 composite were investigated. A change of the tool profile from cylindrical to conical pin profile eliminates particle clusters and inherent voids while the nugget shape, vortex width, and surface flash are also affected due to the tool's volumetric difference. Microstructural changes (grain and particle sizes) are also positively improved by the tapered pin tool, and these have about 24% improvement on the local shear strength of the composite while the hardness and the wear performances of the composite are also improved.

Experimental investigation of mechanical properties of AA6063/ZrO2 metal matrix composites

The experimental investigation of AA6063/ZrO2 metal matrix composites was made by a stir casting method by differing the weight fraction of zirconium dioxide such as 0 wt%, 2 wt%, and 4 wt% and the mechanical properties are studied successfully through various test methods such as microhardness, tensile, and wear. The AA6063/ ZrO2 metal matrix composites of hardness, UTS, and wear test specimens were prepared as per the ASTM standard. From the hardness and UTS test results, the maximum hardness of 71.0 HV, and the maximum ultimate strength of 168.384Mpa were obtained in the sample of AA6063 with 4 wt% ZrO2 composites. A Pin-on-Disc wear test result revealed the lower wear rate of 2.5*10-6 mg/m identified in the test sample of AA6063 with 4 wt% ZrO2 composites. The morphology of AA6063/ ZrO2 composites was studied with help of an SEM test and from its microstructure, uniformly distributed ZrO2 particulates are identified.

Investigations on mechanical behaviour of nano zirconium oxide and graphite particles reinforced copper-tin alloy metal composites

Due to its fundamental mechanical qualities, copper matrix composites (CMC) with reinforcement of graphite (Gr) and nano zirconium oxide (ZrO2) are a more popular composite material for applications in the automotive, aerospace, and marine industries. The properties and quality of the composite material are directly impacted by how difficult it is to distribute reinforcement uniformly throughout the matrix. In the present study, ZrO2 and Gr particles are used to strengthen Cu alloy composites, and their microstructure and mechanical behaviour are examined. In this study, the mechanical characteristics of an alloy consisting of 90% Cu and 10% Sn were compared to various nano ZrO2 and graphite particle compositions. SEM and EDS were used to conduct microstructural study of the mechanical parameters such as hardness, tensile strength, and particle dispersion in matrix composites with reinforcement. After testing, it was discovered that hardness and tensile strength of the composite Cu-Sn alloy with ZrO2 mixture were greater than copper alloy matrix.

Experimental study on mechanical properties of Al5083/ZrO2/B4C hybrid aluminum metal matrix composites

In this paper aluminium metal matrix composite samples are prepared by reinforcing B4C and ZrO2 in Al5083 using stir casting furnace. In this work, two types of AMMCs are prepared. In first type composite, different weight percentages (wt.%) of the nano reinforcement (ZrO2) are added from 0.6 to 1.8 in aluminium matrix. In the second composite, two nano reinforcements ZrO2 and B4C are combinedly added in the wt.% from 0.6 to 1.8 in AMMCs. The prepared composite samples are tested for their tensile strength, hardness, impact strength and wear rate. The hybrid composites show better values compared to ZrO2 composites for same weight percentages and thereby, weight of material could be reduced. Hardness increases with increase in wt.% of Zro2/B4C reinforcements compared to hardness of Zro2 composites for the same quantity of reinforcement. The impact Strength is high for hybrid composite and the low wear rate for same composite. The SEM study revealed that there is uniform distribution of reinforcements in the matrix material and also observed the better bonding between the base metal and the reinforcements. This material is more useful for aerospace application where high strength to weight ratio is required.

Microstructure and Formation Mechanisms of Nanowires and Nanoplates ZrO<sub>2</sub> during the ZrB<sub>2</sub> Deposition Process

Preparation of boride by chemical vapor deposition (CVD) is sensitive to oxygen, subtle changes in oxygen concentration during the deposition of ZrB2 can induce the formation of Zirconium dioxide (ZrO2) with a novel nanoplate-stacked structure and nanowire structure. The ZrO2 nanostructure changed with - oxygen concentration. Nanowires with uniform size of 50-100 nm in diameter and over 100 μm in length were obtained at high oxygen concentration, while highly-ordered nanoplate arrays were obtained at low oxygen concentration. Both of these nanostructures were grown in situ on the surface of ZrB2-coating. In this paper, the preparation method of novelty ZrO2 nano-structures grown in situ was provided, the morphologies and compositions of the nano-structural ZrO2 were characterized and the formation mechanism was proposed, which also provides experimental basis for the industrial morphology control of ZrB2 deposited by CVD method.

Gene Expression Programming Model for Tribological Behavior of Novel SiC-ZrO2-Al Hybrid Composites.

In order to improve product format quality and material flexibility, variety of application, and cost-effectiveness, SiC, ZrO2, and Al hybrid composites were manufactured in the research utilizing the powder metallurgy (PM) technique. A model was created to predict the tribological behavior of SiC-ZrO2-Al hybrid composites using statistical data analysis and gene expression programming (GEP) based on artificial intelligence. For the purpose of examining the impact of zirconia concentration, sliding distance, and applied stress on the wear behavior of hybrid composites, a comprehensive factor design of experiments was used. The developed GEP model was sufficiently robust to achieve extremely high accuracy in the prediction of the determine coefficient (R2), the root mean square error (RMSE), and the root relative square error (RRSE). The maximum state of the RMSE was 0.4357 for the GEP-1 (w1) model and the lowest state was 0.7591 for the GEP-4 (w1) model, while the maximum state of the RRSE was 0.4357 for the GEP-1 (w1) model and the minimum state was 0.3115 for the GEP-3 model (w1).

Interfacial reaction and interface mechanical behaviors of the 2.5D aluminosilicate fiber reinforced ZrO2 composites

The interfacial reaction and interface mechanical behaviors were carefully studied in the 2.5D aluminosilicate fiber reinforced ZrO2 (ASf/ZrO2) composites which had been prepared by polymer impregnation and pyrolysis. The study confirmed that the interfacial reactions can be attributed to the contact of Si-OH with Zr-OH groups and the diffusion of Si4+ in ZrO2 matrix. A chemical bonding significantly formed between the fiber and the matrix. The investigation showed that the interfacial bonding strength enhanced slowly from 113.13 ± 4.83 MPa to 153.01 ± 11.35 MPa with the temperature increasing from 800 °C to 1000 °C, which could be attributed to the interfacial reaction and the great radial compressive stress. At 1100 °C, the interfacial bonding strength declined to 142.11 ± 6.66 MPa. The reason of the decrease could be the shear damage of the interfacial bonding induced by the axial residual stress which were − 476.52 ± 12.47 MPa and 492.57 ± 12.90 MPa in the fiber and in the matrix, respectively.