ZrO2 Composites Research Articles

Biological evaluation of ZrO2 composites modified with different ceramics additives

In this work, zirconia (ZrO2) composites modified with bioactive hydroxyapatite (HAp), hexagonal boron nitride (hBN), bioglass (BG), and bioglass with copper (BGCu) via the hydrothermal method were synthesized. The aim was to obtain highly bioactive and cytocompatible materials that could combine beneficial properties of inert and bioactive ceramics. Such materials could be applied as fillers for tooth extraction cavities, guaranteeing osseintegration without the need to introduce additional bone cements or other adhesives. It was proven that while all materials were favourable towards cells adhesion and growth, the HAp and BG-doped ones facilitated early adhesion, especially when compared to unmodified ZrO2. Only the HAp-doped materials showed satisfactory bioactivity results, with a well-developed apatite layer forming on their surfaces. This study confirms that the Hap-doped ZrO2 is suitable for treating bone defects.

Mechanical Properties of ZrO<sub>2</sub> Particles Reinforced Al2219 Alloy Metal Composites Prepared by Stir Casting Process

The current research focuses on the preparation of Al2219 with micron-sized ZrO2 composite using a liquid metallurgy technique. Al2219 alloy was used to make composites with ZrO2 particles. Microstructural analysis was performed on the created composites using SEM. Hardness, tensile strength and ductility were measured as per ASTM norms. Graphs taken using a scanning electron microscope showed that the boron carbide particles were evenly dispersed throughout the Al2219 alloy. The hardness, ultimate and yield properties of Al alloy were increased by adding ZrO2 particles. Further, Al2219 with 3 and 6 wt.% of ZrO2 composites showed lesser ductility than Al2219 material.

Dynamic creep of Al2O3 whisker-reinforced ZrO2 ceramic composite

Previous studies on the creep behavior of ceramic materials were primarily conducted under static loads. However, the majority of applications for ceramic materials are subject to dynamic loads, and there is a paucity of research conducted in this area. In this work, we report for the first time the creep behavior of Al2O3 whisker-reinforced ZrO2 composites under dynamic pressure. The results showed that the sample crept under dynamic pressure produced higher creep rate and lower activation energy compared to static pressure. By analyzing the creep data and microstructures, we showed that the dynamic pressure can enhance dislocation motion and transform the creep mechanism from diffusion-controlled grain-boundary sliding to dislocation-controlled grain-boundary sliding. This work provides a foundation for subsequent detailed studies of the creep behavior of ceramic materials under dynamic pressure.

Microstructure and fracture behaviour of biomimetic Al2O3-ZrO2 composite with 2-levels of structural hierarchy

We report new class of natural nacre-like alumina toughened by zirconia fabricated by the simple two-step approach of unidirectional freeze-casting and spark plasma sintering. The biomimetic alumina-zirconia with a relative density of more than 98 % was achieved by consolidating at temperature of 1300–1425 °C with 50 MPa pressure. The resultant microstructure consists of two levels of structural hierarchy, i.e. level-1: bulk lamellar brick phase (alumina platelets) and level-2: mortar phase (yttria stabilized tetragonal zirconia polycrystals). The increase in volume fraction of zirconia (in tetragonal form) from 0 to 15 vol% was effective in progressively reducing the size of alumina platelets from 12 to 9 μm, and significantly improved the flexural strength of the composite by 60 % (from 172 to 270 MPa). By optimizing the hierarchical architecture from micro to macroscopic level, the structural performance of our synthetic nacre, where strength and toughness of 270 MPa and 13.5 MPa√m respectively are superior to that of natural nacre and many other engineering materials (illustrated in the form of Ashby map). The exceptional damage resistance is rationalized by both intrinsic (stress induced tetragonal to monoclinic phase transformation of zirconia) and extrinsic (crack deflection, crack branching and bridging, multiple cracking, platelets interlocking) toughening mechanisms. For 15 vol% ZrO2 composition, the contribution of intrinsic and extrinsic toughness was quantitatively evaluated as 0.9 ± 0.03 and 4.3 ± 0.07 MPa√m respectively (with experimentally measured toughness at crack initiation as 5.2 ± 0.2 MPa√m).

Interfacial engineering of (Ce,Zr)O2 composite barrier layers for enhancing the durability of solid oxide fuel cells

The dense GdxCe1-xO2 (GDC) barrier layer can't prevent the diffusion of small amounts of Sr through grain boundaries. Recent studies indicate that the (Ce,Zr)O2 composite, placed between GDC and YSZ (Y2O3 stabilized ZrO2) electrolyte, can effectively suppress SrZrO3 formation. In this study, we successfully designed and prepared an anode-supported solid oxide fuel cell (SOFC) with a dense GDC/IDL (interdiffusion layer) composite barrier layer, demonstrates excellent inhibition of elemental diffusion through grain boundaries. Compared with the cell with a single dense GDC barrier layer, the cell with GDC/IDL composite barrier layer exhibits largely improved durability, with a two-fold decreased degradation rate of 2.7 %/kh, operated under constant current density of 400 mA/cm2 at 720 °C. The cell with GDC/IDL barrier layer presents decreased initial performances, with lager Rohm of 0.085 Ω cm2 than 0.075 Ω cm2, and smaller initial Pmax of 0.905 W/cm2 than 1.019 W/cm2 at 750 °C. However, the cell performance surpasses the cell with single GDC barrier after 230 h. Thus, we obtain a new strategy to achieve improved cell durability by sacrificing the cell's initial performance. The in-situ constructed continuous and dense GDC/IDL composite optimizes the electrolyte/cathode interface while maintaining decent electrochemical performance, providing a new horizon to design and prepare high performance and durable SOFCs.

Prediction of specific wear rate of Al7050-12 wt% ZrO2 composite using box-behnken design approach

Prediction of specific wear rate of Al7050-12 wt% ZrO2 composite using box-behnken design approach

Improved sinterability and thermal shock resistance of MgO–ZrO2 composites due to in-situ formed MgAl2O4

To solve the problems of high cost and high firing temperature of ZrO2 inserted rings of slide plates, the in-situ MgAl2O4 (MA) toughened MgO–ZrO2 new ring materials were prepared using lightly calcined MgO, m-ZrO2 and nanoscale Al2O3. The effects of MgO/ZrO2 ratio and the amount of nanoscale Al2O3 on properties of samples were investigated. The results showed that the sinterability and mechanical properties of MgO–ZrO2 composites improved significantly due to the MA formed in situ by reaction between MgO and Al2O3, which promoted reactive sintering and densification of the samples. The improved thermal shock resistance (TSR) in MA-toughened MgO–ZrO2 composites was attributed to microcracks developed due to thermal expansion mismatch, MA and ZrO2 also acted as bridging particles, improving the ability to prevent crack propagation of the composites. The optimum MgO/ZrO2 ratio and addition amount of nanoscale Al2O3 were 7/3 and 3 wt%, respectively.

Determination of gamma radiation shielding efficiency by radiation-resistant composite ZrO2–Al2O3 – TiO2–WO3 – Nb2O5 ceramics

This work examines the prospects of using composite ZrO2–Al2O3 – TiO2–WO3 – Nb2O5 ceramics as shielding and radiation-resistant materials as structural materials in conditions of heightened radiation background, including gamma radiation and exposure to heavy ions. The key objective of the study is to determine the impact of the variation in composite ceramic composition on resistance to radiation damage caused by exposure to heavy ions comparable to nuclear fuel fission fragments, and to establish the effect of the radiation damage accumulation on the shielding characteristics of these ceramics, the maintenance of which determines the stability of the operation of nuclear materials by eliminating the ionization factor caused by the interaction of gamma quanta. During the studies, it was found that alterations in the phase composition of composite ceramics associated with the formation of ZrTiO4, AlWO3 and Nb2W3O14 phases in the structure lead not only to strengthening of the ceramics, but also to a rise in resistance to radiation damage, and associated changes in the damaged layer degradation, having an adverse impact on the shielding characteristics.

Effect of TiC addition on microstructure and properties of network structured TiC–ZrO2 composite conductive ceramics

Zirconia (ZrO2) ceramics have excellent mechanical properties and high-temperature conductivities. However, ZrO2 ceramics do not possess room-temperature conductivity, which significantly limits their application as functional components in smart communication devices and wearable smart products. To achieve room-temperature conductivity in ZrO2 ceramics, this study prepared a network-structured TiC–ZrO2 composite conductive ceramic with a low titanium carbide (TiC) addition using pressureless sintering. The influence of the TiC addition on the microstructure, mechanical properties, and electrical properties of the TiC–ZrO2 composite material was investigated. The results showed that the composite material consists of cubic zirconia (c-ZrO2), tetragonal zirconia (t-ZrO2), and titanium carbide (TiC) phases. When the TiC content was 11 vol %, the relative density, open porosity, flexural strength, and fracture toughness of the sample were 98.6 ± 0.1 %, 0.16 ± 0.06 %, 383 ± 38 MPa, and 4.66 ± 0.26 MPa m1/2, respectively. The electrical percolation threshold of the TiC–ZrO2 composite was between 8.0 and 11.0 vol %. When the TiC content is 18.8 vol %, the sample exhibited the lowest room-temperature resistivity of 3.00 × 10−5 Ω m. The electrical resistance of the TiC–ZrO2 composite material is mainly attributed to the grain boundary effect. With increasing TiC content, the resistivity of the composite material decreased, exhibiting linear conductivity and achieving conductive percolation characteristics.

Al2O3/Y3Al5O12 (YAG)/ZrO2 composites by single-step powder synthesis and spark plasma sintering

Alumina-yttrium aluminum garnet (YAG)-zirconia composites are often produced by the melt solidification method. In the present study, we investigated the fabrication of α-Al2O3/Y3Al5O12 (YAG)/ZrO2 composite by Spark Plasma Sintering (SPS) of powders synthesized by Pechini’s sol-gel method. The ternary composites with homogenous microstructure and high density were produced by SPS at 1300 °C for 15 min. The addition of ZrO2 promoted the sintering of composites, resulting in a higher density and, in turn, higher hardness. A change in the indentation fracture behavior as the result of ZrO2 addition was observed.

Effects of Ti Addition on the Characteristics of Al-10Zn-6Mg-2Si/ZrO2 Composites Produced by Squeeze Casting

Effects of Ti Addition on the Characteristics of Al-10Zn-6Mg-2Si/ZrO2 Composites Produced by Squeeze Casting

Phase Formation and Diamond Retention in Cdiamond–(WC–Co)–ZrO2 Composites Formed by Spark Plasma Sintering Method

Phase Formation and Diamond Retention in Cdiamond–(WC–Co)–ZrO2 Composites Formed by Spark Plasma Sintering Method

Toughening of (MgCoNiCuZn)O through addition of ZrO2(3Y) prepared by ultrafast high-temperature sintering

To achieve low-cost preparation of high-performance high-entropy oxide, ZrO2(3Y)-reinforced (MgCoNiCuZn)O matrix composite ((MgCoNiCuZn)O–ZrO2(3Y)) was prepared in a few seconds by ultrafast high-temperature sintering (UHS) technology in this work. Microstructure, phase composition, crystal structure, and mechanical properties of the (MgCoNiCuZn)O–ZrO2(3Y) composite were investigated systematically. The results indicated that, after UHS sintering with applied current of 22 A for 2 min, the enhancement of ZrO2(3Y) were well dispersed in the (MgCoNiCuZn)O matrix. The microhardness and fracture toughness of the UHSed (MgCoNiCuZn)O–ZrO2(3Y) were 6.43 GPa and 2.27 MPa·m0.5, which were much higher than those of the traditional sintered (MgCoNiCuZn)O–ZrO2(3Y) (1.65 GPa and 0.98 MPa·m0.5) and UHSed (MgCoNiCuZn)O without ZrO2(3Y) (4.06 GPa and 1.42 MPa·m0.5). The toughening mechanism of the UHSed (MgCoNiCuZn)O–ZrO2(3Y) was discussed in detail based on the microstructural feature and crack propagation behavior. In summary, this study provided insight into the advantages of incorporating ZrO2(3Y) and UHS technology to reinforce high-entropy oxides.

SYNTHESIS OF MULTICOMPONENT ZRO<SUB>2</SUB>:WO<SUB>3</SUB>:AL<SUB>2</SUB>O<SUB>3</SUB>:MGO

In this work, the phase composition and microstructure of multicomponent ZrO2:WO3:Al2O3:MgO ceramics were studied depending on the concentration of the components. The dependences between the concentration of elements in the initial charge and the phase composition, volume shrinkage, density and microstructure of synthesized samples are determined. It was found by Raman spectroscopy that the addition of an Al2O3:MgO mixture to the initial ZrO2:WO3 matrix does not lead to the formation of a ZrO2:WO3:Al2O3:MgO solid solution. With an increase in the content of Al2O3:MgO, there is an increase in volumetric shrinkage and density, which may be associated with the formation of the liquid phase of the WO3:Al2O3 system at a temperature of 1450 °C and, as a result, more efficient migration of pores and defects to the surface. The analysis of the SEM images of the cross sections of the obtained samples showed that all samples have a developed morphology with different grain shapes.

Attaining translucency in binder/additive-free, nanograined, tetragonal 1.5 mol.% yttria-stabilized zirconia ceramics

In the quest of minimum yttria content to stabilize tetragonal zirconia system, we report the synthesis of ultrafine (∼9 nm), near-spherical, phase-pure tetragonal 1.5 mol.% yttria-stabilized zirconia (1.5YSZ) nanoparticles. The pressureless sintering process (at 1100 °C) involved of 1.5YSZ nanopowders (without any slurry processing) and did not need any binders, additives, or sintering aid to attain high-density (>98.5%) and refined grain size (∼50 nm) for the consolidated fully tetragonal 1.5YSZ nanoceramics. A promising transmittance value of 46% (at 630 nm) was obtained, making it comparable/higher in optical properties with respect to the transmittance values of existing 3 mol.% yttria-doped ZrO2 compositions. This result is credited to our synthesized phase-pure (validated via X-ray Diffraction and Raman analysis) near-spherical nanoparticles with improved tetragonality (c/a ratio = 1.439, obtained via Rietveld analysis) that paved the way for low-temperature conventional sintering for possible large-scale industrial applications.

Processing of ZrO2 strengthened and toughened WC matrix composites based on ML

Binderless WC matrix cemented carbide was considered a novel material with the potential to replace WC-Co cemented carbide. However, current research was insufficient to address the trade-off between strength, toughness, and strength in binderless WC matrix cemented carbide. In this work, the machine learning was employed to estimate mechanical property and optimize the composition of WC matrix cemented carbide. WC-MgO-ZrO2 composites were successfully developed with uniform microstructure and excellent mechanical properties. The experimental results showed that the grain size of WC reached 1.05μm where the mass fraction of ZrO2 was 2%. The WC-MgO-2 wt%ZrO2 composite exhibited superior Vickers hardness, fracture toughness, and flexural fracture strength, which were 1851HV, 11.2 MPa·m1/2 and 1368 MPa, respectively. The fracture mode of WC-MgO-ZrO2 composites was mainly a mixture of transgranular fracture and intergranular fracture. The main toughening mechanisms were crack deflection, crack bridging, grain pull out and phase transformation. The comprehensive mechanical properties of WC-MgO-2 wt%ZrO2 composites rank at a superior level compared to similar binderless WC matrix composites reported in the current literature. Meanwhile, the wear behaviors of WC-MgO-ZrO2 composites were examined under three different loads. And the wear behavior and mechanism of WC MgO-2 wt% ZrO2 composite were revealed.

Effect of Addition of ZrO2 on Biaxial Flexural Strength of Calcium Phosphate Ceramics

The aim of this study is to investigate the effect of addition of ZrO2 on the biaxial flexural strength (BFS) of ceramics fabricated using a conventional powder technology. Various compositions of hydroxyapatite (HAp) Ca10(PO4)6(OH)2 and zirconia powder ZrO2, ranging from 10 to 90 wt% ZrO2, were prepared using a wet mixing process. Ten compacts (13.5mm3mm) were made for each group, pressed and sintered in air at sintering temperatures from 1100 to 1450oC for up to 12 hours. The bulk density, porosity, linear shrinkage and BFS. The porosity reduced and linear shrinkage increased with increasing sintering temperature and amounts of zirconia, whereas the sintering time had little effect. The highest mean value achieved for the BFS was 26920 MPa for a composition of 70% ZrO2 and 30% HAp fired at 1450oCfor 6 hours. From the experimental results can be conclude that sintering temperature and composition affect densification behaviour of calcium phosphate/ ZrO2 composites. The BFS increases with a reduction of porosity and increases with both sintering temperature and additions of ZrO2. It was noted that there is considerable scope for improvement in the BFS values by reducing the porosity of these composites.

Retracted: Tribological Behavior of AA7075 Reinforced with Ag and ZrO2 Composites

Retracted: Tribological Behavior of AA7075 Reinforced with Ag and ZrO₂ Composites

Numerical analysis of the mechanical behavior of ceramic dental implants based on Ce-TZP/Al2O3 composite

This study aimed to identify the potential use of the ceramic composite ZrO2(CeO2)–Al2O3 as a dental implant due to its intrinsic geometry and different masticatory loads based on finite element simulations. Ceramic samples were sintered at 1500 °C-2h, and characterized: The mechanical properties of the ceramic composite (hardness, fracture toughness, flexural strength, Young's Modulus, and Poisson ratio) were determined, in addition to the relative density and its structural characteristics. Commercial dental implant designs (incisal and third-molar) on CAD models were used in this study as an initial implant geometry applied in a typical simulated mandible anatomy. Finite element models were generated for implant geometries using CAD and CAE techniques. Loading cases were considered based on different intensities (100–500 N) and orientation angles to the implant axis (0° and 45°) to reproduce human masticatory conditions. For comparison purposes, the numerical predictions were compared with finite element simulations of gold-standard titanium implants. Ce-TZP/Al2O3 sintered ceramics showed flexural strength of 952.6 ± 88 MPa, hardness and fracture toughness of 1427 ± 46 HV and 11.3 ± 0.4 MPa m1/2, respectively, beside Young's modulus of 228.3 ± 65 GPa and Poisson ratio of 0.28. For both Ce-TZP/Al2O3 dental implant geometries, the implant prototypes showed adequate mechanical behavior regardless of the masticatory load value or the orientation angle applied in the simulations: All finite element predictions are lower than the values established by Mohr Coulomb's failure criterion, allowing the feasibility, preliminarily, of the proposed ceramics for dental implant applications without fracture risk.

Compositional Grading of Al<sub>2</sub>O<sub>3</sub>/ZrO<sub>2</sub>/SUS304 Hybrid Materials Using Centrifugal Slurry Methods and Spark Plasma Sintering

Ceramic/ metal functionally graded materials (FGMs) have been promising to sustain coating structures working under super high temperature as well as high temperature gradient conditions. Compositional gradients in the FGMs can be engineered according to functional performance requirements. This study aims to fabricate Al2O3/ZrO2/SUS304 hybrid FGMs with continuous compositional gradient manners using a combination of centrifugal slurry methods and spark plasma sintering (SPS). The compositional gradients in the FGMs were investigated on microstructures with elemental distributions and hardness on the cross sections of the FGMs. It was demonstrated that the compositions of ZrO2 and SUS304 continuously varied in the FGMs, while Al2O3 resided only on ZrO2-rich sides, which can effectively enhance the fracture toughness of the ZrO2-rich layer. Ball milling treatments can make the Al2O3 layer more formed in the ZrO2-rich layer. With increasing the amount of Al2O3, the Al2O3 layer resided closer to the top of the ZrO2 surfaces in the FGMs subject to ball milling treatments, which can prevent the crack propagation from the ZrO2 top surfaces.