Addition Of Yttria Stabilized Zirconia Research Articles

ENHANCEMENT IN MICROSTRUCTURAL CHARACTERISTICS AND MECHANICAL PROPERTIES OF A6082-BASED MMCS VIA YTTRIA STABILIZED ZIRCONIA INCORPORATION AND T6 HEAT TREATMENT

This study investigates the impact of Yttria Stabilized Zirconia (YSZ) and T6 heat treatment on the mechanical and microstructural properties of A6082-based Metal Matrix Composites (MMCs) prepared using the conventional stir casting route. A6082 is widely used in various industrial applications due to its excellent physical, structural and functional properties with good corrosion resistance. YSZ with superior mechanical and thermal properties that can enhance the strength and wear resistance of aluminium-based composites. T6 heat treatment is a widely adopted technique to improve the material properties of aluminium alloys. The results of this study indicate that the T6 heat treatment significantly refines the grain structure of the composites, resulting in improved hardness and tensile values compared to untreated samples. Mechanical properties are also enhanced by YSZ's integration into the composites, with a 9wt.% YSZ addition to the matrix alloy leading to a noticeable improvement in hardness for both the untreated and treated composites. The tensile parameters show a similar trend, with a gain in Ultimate Tensile Strength and Yield Strength up to 6wt.% YSZ addition, after which the findings follow a downtrend (at 9wt.%). The results of this research show that A6082/YSZ composites subjected to T6 heat treatment have great promise as a high-performance material.

Microstructure and biocorrosion studies of spark plasma sintered yttria stabilized zirconia reinforced Ti6Al7Nb alloy in Hanks' solution

A study of spark plasma sintered Ti6Al7Nb alloy reinforced with yttria stabilized zirconia (YSZ) has been carried out to assess the biocorrosion response in Hank's solution. The results indicate that the microstructural changes resulting from YSZ addition to Ti6Al7Nb were considerably different from pure Ti6Al7Nb. All the Ti6Al7Nb + YSZ composites showed a higher Vickers microhardness value with Ti6Al7Nb + 10%YSZ exhibiting the most enhanced hardness value of 955.3 HV0.1. Furthermore, all Ti6Al7Nb + YSZ present higher corrosion resistance in Hank's solution than Ti6Al7Nb alloy except Ti6Al7Nb + 1YSZ which shows a significant drop in Ecorr and Icorr values. This could be due to grain refinement with less stable oxide film growth kinetics. The combination of mechanical property and corrosion resistance of the fabricated Ti6Al7Nb + YSZ alloy could make it a suitable material for dental implant in the nearest future.

Sintering and thermal expansion behaviors of glass and glass–YSZ composites as self‐repairable seals for SOFC

AbstractGlass and glass–ceramics are used as sealants in solid oxide fuel cell (SOFC) because their thermophysical properties can be tailored to meet the stringent requirements of the SOFC stack. The processing, sintering, and thermal expansion behaviors of self‐healing and non‐crystallizing glass and glass containing 10%–30 wt.% non‐reacting yttria‐stabilized zirconia (YSZ) are studied. The addition of inert YSZ to glass significantly retarded the sintering behavior. Thermal expansion behaviors of glass and glass–YSZ are also measured to study the role of YSZ addition on the glass transition, softening point, and coefficient of thermal expansion (CTE). It is shown that the densification is controlled by the viscous sintering mechanism, in which the addition of YSZ increased the effective viscosity of the glass–YSZ as evident from higher glass transition and softening temperatures and decreased CTE. These results demonstrated that the addition of YSZ to glass is promising for achieving optimum thermophysical properties useful as seals for SOFC.

Synthesis of γ‐Bi 2 O 3 /YSZ composite powders using a facile precipitation method

Low melting point and high ionic conductivity of γ-Bi2O3 make it a promising additive to decrease the sintering and operation temperatures of yttria stabilized zirconia (YSZ)-based electrolyte for solid oxide fuel cell application. Herein, γ-Bi2O3/YSZ composite powders with good uniformity and precise control of morphology and phase were successfully synthesized via a low cost chemical precipitation method. Both the concentration of NaOH solution and the reactant adding sequence affect the morphology and synthesis of γ-Bi2O3/YSZ composite powders. When the concentration of NaOH was in the range of 1.25–1.875 M, tetrahedron γ-Bi2O3/YSZ powders were synthesized. While, cubic structural γ-Bi2O3/YSZ powders were obtained when adding Bi3+ and YSZ suspension into 1.5 M NaOH solution. The addition of YSZ facilitates the fabrication of γ-Bi2O3 and widens its process window to a higher NaOH concentration. Thus synthesized γ-Bi2O3/YSZ composite powders effectively decrease the sintering temperature of YSZ to 1050°C due to the uniform distribution of γ-Bi2O3 inside YSZ powders. This work provides a facile method to fabricate γ-Bi2O3/YSZ composite powder with controlled morphology and phase, which will promote the mass production of low cost YSZ-based electrolyte for SOFC applications.

The influence of yttria-stabilised zirconia and cerium oxide on the microstructural morphology and properties of a mica glass-ceramic for restorative dental materials

ABSTRACT The addition of yttria-stabilized zirconia and cerium oxide to this mica glass ceramic was found to increase mechanical properties and decrease chemical solubility. They were also found to be able to control translucency. X-ray diffraction showed no significant change in phase formation with phlogopite-Ca mica, fluorapatite and tetragonal zirconia the main phases present with their addition. Scanning electron microscopy showed that the additives did affect the grain morphology significantly and this was the controlling factor in the observed changes in strength, hardness, and solubility. The microstructures consisted of mainly plate-like and interlocking crystals. The largest increased in strength and hardness and the largest decreased in chemical solubility can be attributed to the largest change in grain morphology by the addition of both the YSZ and CeO2. The values of hardness, biaxial flexural strength and chemical solubility were 3.5–6.2 GPa, 105–120 MPa and 142–732 µg/cm2, respectively making them acceptable for dental materials according to ISO 6872:2015. The addition of YSZ increased the opacity, whilst the CeO2 improved translucency and influenced the color to a yellowish to yellow-brownish shade close to Thais’ teeth.

Influence of yttria-stabilized zirconia content on rheological behavior and mechanical properties of zirconia-toughened alumina fabricated by paste-based stereolithography

Improvement of the mechanical properties of advanced ceramics fabricated by additive manufacturing has been a prerequisite for their wide applications. In this work, zirconia-toughened alumina (ZTA) parts with a variety of yttria-stabilized zirconia (YSZ) content were fabricated by stereolithography (SL) technology, based on the appropriate self-holding ability of the viscoelastic paste and application of conformal contactless support strategy. Combining microstructural analysis and mechanical assessment by three-point bending and indentation tests, the influence of YSZ content on the SL process and subsequent mechanical properties was discussed. The results showed that the optimized matching of flexural strength (477.54 MPa) and fracture toughness (6.56 MPa m1/2) was acquired by ZTA ceramic with a YSZ content of 20 wt%. When the YSZ content reached 30 wt%, agglomerations formed and led to a negative influence on the properties of ZTA ceramics. It is confirmed that the combined contribution from the addition of YSZ on the improvement of mechanical property and influence of the SL process should be synthetically considered during the design of ceramic paste feedstock for such additive manufacturing.

Nickel, Graphene, and Yttria-Stabilized Zirconia (YSZ)-Added Mg by Grinding in Hydrogen Atmosphere for Hydrogen Storage

Magnesium (Mg) has good hydrogen storage features except for its slow reaction kinetics with hydrogen and high hydride decomposition temperature. Yttria (Y2O3)-stabilized zirconia (ZrO2) (YSZ), nickel (Ni), and graphene were picked as additives to Mg to solve these problems. Samples with a composition of 92.5 wt% Mg + 2.5 wt% YSZ + 2.5 wt% Ni + 2.5 wt% graphene (designated as Mg + YSZ + Ni + graphene) were prepared by grinding in hydrogen atmosphere. The activation of Mg + YSZ + Ni + graphene was finished at the third cycle (n = 3). Mg + YSZ + Ni + graphene had an efficient hydrogen storage capacity (the amount of hydrogen absorbed for 60 min) over 7 wt% (7.11 wt%) at n = 1. Mg + YSZ + Ni + graphene contained Mg2Ni phase after cycling. The addition of Ni and Ni + YSZ greatly increased the initial hydride formation and decomposition rates, and the amount of hydrogen absorbed and released for 60 min, Ha (60 min) and Hd (60 min), respectively, of a 95 wt% Mg + 5 wt% graphene sample (Mg + graphene). Rapid nucleation of the Mg2Ni-H solid solution in Ni-containing samples is believed to have led to higher initial decomposition rates than Mg + graphene and Mg. The addition of YSZ also enhanced the initial decomposition rate and Hd (60 min) compared to a sample with a composition of 95 wt% Mg + 2.5 wt% Ni + 2.5 wt% graphene (Mg + Ni + graphene).

Microstructure and tribological properties of laser cladded TiAlSi composite coatings reinforced by yttria-stabilized zirconia

The YSZ (yttria-stabilized zirconia)/TiAlSi composite coatings were successfully fabricated on Ti–6Al–4V alloy substrates by laser cladding technology. The effects of YSZ content on the microstructure and properties of the laser cladding TiAlSi composite coatings were investigated by optical microscope, scanning electron microscope, x-ray diffractometer, hardness tester, as well as friction and wear testing apparatus. The results show that YSZ reinforced Ti-based composite coatings are mainly composed of TiAl, Ti3Al, Ti5Si3, Al2O3, TiO2, SiO2 and ZrO2. With the increase of YSZ content from 0%–5%, the microhardness of the coatings increases, which reaches a maximum of around 803 HV0.3 when the addition content is 5%. The average coefficient of friction of the coating without YSZ is 0.592, while that of the coatings with 1%, 3% and 5% YSZ contents is 0.433, 0.581 and 0.429, respectively. The composite coating with 5% content of YSZ particles possesses the lowest coefficient of friction. The average wear volume loss of the coating without YSZ is 0.78 mm3, which is higher than that of the coatings with the addition of YSZ. The composite coating with 5% content of YSZ particles possesses the lowest wear volume loss. Its worn surface is smoother than the other coatings.

Development of proton conducting fuel cells using nickel metal support

This research reports the fabrication of a metal supported fuel cell based on the well-known proton conducting electrolyte (PCE) BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) material. The impact of the addition of YSZ on the anode microstructure is also described. This solid oxide fuel cell (SOFC) consists of Ni:yttria stabilized zirconia (YSZ) support (with different weight ratios of Ni:YSZ), Ni-BZCYYb anode functional layer (AFL), BZCYYb electrolyte and LSCF-BZCYYb cathode. The results show that addition of only 10 wt% YSZ to the support improves the microstructure of the cell by preventing severe Ni grain growth inside the support, and providing more accessible triple phase boundaries (TPBs) at the contact surface of the support/AFL and better distribution of the fuel gas to the accessible TPBs. As a result of microstructural improvement, polarization resistance of the cells with 10 wt% YSZ decreases compared with the cell having pure Ni metal. The cell containing YSZ in the support shows 67 h of stable operation under potentiostatic SOFC condition without any degradation. The current metal supported tubular fuel cell shows promising electrochemical and microstructural features which has the possibility to replace the conventional (Ni-PCE) or even Ni-YSZ anode supports.

Effect of YSZ with different Y2O3 contents on toughening behavior of Al2O3/Ba-β-Al2O3/ZrO2 composites

Al2O3 matrix composites containing in-situ formed monoclinic zirconia (m-ZrO2) and BaO·7.3Al2O3 (one of Ba-β-Al2O3 compounds) were prepared via reactive sintering of Al2O3 and BaZrO3 powders. When yttria-stabilized zirconia (YSZ) with Y2O3 contents of 1.5 mol% (1.5YSZ), 2 mol% (2YSZ), and 3 mol% (3YSZ) as well as Y2O3 particles were introduced into Al2O3 and BaZrO3 powder mixtures, the in-situ formed m-ZrO2 was stabilized, resulting from the migration of Y3+ from YSZ or Y2O3 to m-ZrO2 during sintering. The incorporation of YSZ contributed to the refinement of Al2O3 grains, whereas Y2O3-added samples showed larger grain sizes of Al2O3 matrix. The samples with YSZ or Y2O3 addition exhibited high fracture toughness, which is attributed to crack deflection/bridging and transformation toughening of ZrO2. Although the phase transformation is mainly derived from ZrO2 formed during sintering, 1.5YSZ particles added in the composites still showed much higher phase transformability compared to 2YSZ and 3YSZ particles.

Effect of Addition of Multimodal YSZ and SiC Powders on the Mechanical Properties of Nanostructured Cr2O3 Plasma-Sprayed Coatings

In this research, the effect of the addition of multimodal yttria-stabilized zirconia (YSZ) and SiC reinforcements on the mechanical properties of Cr2O3 plasma-sprayed coatings was studied. For this purpose, the starting powders were ball milled for 5 h and then mixed and agglomerated, prior to spraying. Cr2O3, Cr2O3-20YSZ (CZ), and Cr2O3-20YSZ-10SiC (CZS) coatings were then deposited onto 304L steel substrates using the atmospheric plasma spray process. Microstructural evaluations of the initial/milled powders and the plasma-sprayed coatings were conducted through x-ray diffraction, field emission scanning electron microscopy (FESEM) equipped with energy-dispersive x-ray spectroscopy and porosity measurements. The microscopic images indicated that the multimodal milled powders resulted in nanostructured coatings. Mechanical tests including adhesive strength, fracture toughness, and micro-hardness were used to understand the dependence of the properties of coatings and their microstructure. Adding tough YSZ particles to the C coating considerably increased the toughness through the phase transformation-toughening mechanism of tetragonal zirconia while decreasing micro-hardness of the coating; therefore, intrinsically hard SiC particles were added to the CZ coating to deal with the reduced hardness. Moreover, when compared to pure C coating, CZ, and CZS Composite coatings showed comparable bonding strengths and higher porosities.

Assessment of the performance of Y2SiO5-YSZ/YSZ double-layered thermal barrier coatings

Y2SiO5 is a promising material for the thermal barrier coatings due to its low thermal conductivity, high temperature stability and exceptional resistance for molten silicate attack. However, it suffers low fracture toughness and low coefficient of thermal expansion compared with yttria-stabilized zirconia (YSZ). In this study, a composite coating approach, i.e., incorporating YSZ into Y2SiO5 coating, was employed to overcome those limitations. The double-layered Y2SiO5-YSZ/YSZ coatings were fabricated using atomospheric plasma spraying and tested under thermal cycling at 1150 °C. The phase compositions, microstructure, mechanical properties and the failure behavior were evaluated. It was found that the amorphous phase during spraying would crystallize at high temperature accompanied by volume shrinkage, leading to cracks and spallation in the coating. With YSZ addition, the composite coatings exhibited a much longer lifetime than the single phase Y2SiO5 coating due to a lower volume shrinkage and enhanced toughness.

Microstructure and improved mechanical properties of Al2O3/Ba-β-Al2O3/ZrO2 composites with YSZ addition

Al2O3/Ba-β-Al2O3/ZrO2 composites were fabricated by solid-state reaction sintering of Al2O3, BaZrO3, and yttria stabilized zirconia (YSZ) powders. The effects of YSZ addition on microstructure and mechanical properties have been investigated. The incorporation of YSZ promoted the densification of the composites and formation of tetragonal ZrO2 phase. The microstructure of the composites was characterized by elongated Ba-β-Al2O3 phase and equiaxed ZrO2 particles including added YSZ and reaction-formed ZrO2. The Al2O3/Ba-β-Al2O3/ZrO2 composites with YSZ addition exhibited improved fracture toughness, as a result of multiple toughening effects including crack deflection, crack bridging, crack branching, and martensitic transformation of ZrO2 formed by the reactions between Al2O3 and BaZrO3. Moreover, owing to the grain refinement of Al2O3 matrix, dispersion strengthening of the added YSZ particles, and an increase in density of the composites, the Vickers hardness and flexural strength of Al2O3/Ba-β-Al2O3/ZrO2 composites were dramatically enhanced in comparison with the composites without YSZ addition.

Effect of YSZ-dopant on microstructure and hardness property of the Al2O3–40%TiO2 plasma sprayed coating

The Al2O3–40%TiO2 (AT40) coating doped with the different contents of Yttria-stabilized zirconia (YSZ) on mild steel prepared by plasma spraying was studied. The different compositions of the YSZ powders are varied by 8 wt% and 20 wt%. The coating with 20 wt% YSZ exhibits a smaller wear rate and better hardness property than that with 8 wt% YSZ, which could be found through the wear resistance and Vickers hardness tests. The YSZ addition promotes the formation of Al0.1Zr0.9O1.95 and then increases the wear and hardness properties of the composite ceramic coating.

Effect of 3 mol% Yttria Stabilized Zirconia Addition on Structural and Mechanical Properties of Alumina-Zirconia Composites

Alumina-Zirconia (Al2O3-ZrO2) composites especially Zirconia Toughened Alumina (ZTA) shows better mechanical properties over alumina. Al2O3-ZrO2 composites were prepared by powder compaction method varying 3 mol% yttria stabilized zirconia (3Y-ZrO2) content from 0 to 20 vol% using small amount of MgO as sintering aid. The composites were sintered for two hours in air at 1580°C. At this temperature maximum density was achieved 99.31% of theoretical density for composite containing 20 vol% 3Y-ZrO2. Density measurement of sintered composites was carried out using Archimedes’s method. Hardness and fracture toughness measurement was carried out using Vickers indentation. Phase content and t-ZrO2 retention were detected by means of X-ray diffraction (XRD). Microstructure of the composites and grain size of alumina and zirconia was determined by Scanning Electron Microscopic (SEM) analysis. Maximum microhardness (17.46 GPa) was achieved for composite containing 5 vol% ZrO2 and maximum flexural strength (684.32 MPa) and fracture toughness (10.33 MPam0.5) was achieved for composite containing 20 vol% of 3Y-ZrO2. The aim of the present work is to investigate the optimum 3Y-ZrO2 content for obtaining maximum density, microhardness, flexural strength and fracture toughness of Al2O3-ZrO2 composites.

Development of storage materials for high-temperature rechargeable oxide batteries

A high-temperature rechargeable oxide battery (ROB) comprises a regenerative solid oxide cell (SOC) and oxygen-ion storage that consists of a porous Fe2O3 base redox material. This material possesses good redox kinetics, a high oxygen-ion storage capacity, and an acceptable long-term stability. Yet, observations demonstrate degradation effects such as particle coarsening and an outward diffusion of iron leading to layer formation during operation of the ROB at 800°C.To clarify the influence of the material composition on degradation, various oxides were added as a stabilizing scaffold for the Fe2O3 base material. Pressed samples of the binary mixtures were sintered in air at 900°C and subsequently redox-treated up to 20 times under conditions that simulate those present in an actual ROB (800°C, Ar–2%H2 or Ar–7%H2O–2%H2). Afterwards, the degradation properties were analyzed by laser microscopy and the phase composition was measured using X-ray diffraction. Results indicate that the addition of yttria-stabilized zirconia (8YSZ) or pure zirconia (ZrO2) can suppress structural degradation thus maintaining reaction kinetics. In contrast, the use of yttria (Y2O3) does not significantly mitigate degradation phenomena. Consequently, storage components consisting of 8YSZ and Fe2O3 were employed in an ROB test, resulting in more than 200 cycles with a current density of 150mA/cm2 and cycle durations of up to 70min.

Strength evaluation of glass–ceramic composites containing yttria stabilized zirconia after thermal cycling

The effect of YSZ (yttria stabilized zirconia) on the thermal cycling stability of commercial glass–ceramics powders as a solid oxide fuel cell (SOFC) sealant material is investigated. Four different composite sealants are prepared including 1, 3, 5 and 10wt% of YSZ with respect to the total powders. A sealant without YSZ is also prepared as the base case for comparison. The fabrication of the sealant is achieved by using cost-effective tape casting routes. The samples are then placed between two metallic interconnectors and a high temperature glass forming process is performed. The mechanical performances are measured via tensile tests before and after a number of thermal cycles. The results indicate that the fracture strength is adversely affected by the amount of YSZ loading due to reduced glass–ceramics powders in the composites. However, when the thermal cycling stability is the issue, the samples with YSZ show relatively small rate of decrease. Therefore, the addition of YSZ is found to be beneficial for improving the thermal cycle stability of glass–ceramics. The optimum YSZ content is determined to be 5wt%, since these samples exhibit almost a stable mechanical performance after each thermal cycles considered in this study.

Application of advanced morphology Au–X (X = YSZ, ZrO2) composites as sensing electrode for solid state mixed-potential exhaust NOx sensor

Among various NOx sensors developments, mixed potential sensor based on Yttria Stabilized Zirconia (YSZ) with a simple planar architecture Au/YSZ/Pt is of practical interest. Au composites electrodes were investigated to improve sensing performances. Such potentiometric solid-state gas sensors – were fabricated by screen-printing and tested for NO2 detection. Electrochemical impedance spectroscopy has shown that the addition of YSZ in the Au electrode decreased the polarization resistance in air. In addition, the (Au+10wt% YSZ)/YSZ/Pt sensor has a shorter response time and higher sensitivity to NO2 (range 20–100ppm) at 450–550°C in comparison with a reference Au/YSZ/Pt sensor. On the other hand, the addition of non-conductive ZrO2 does not significantly modify the electrochemical property but strongly damages the sensor responses toward NO2.

The Effects of YSZ-Al<sub>2</sub>O<sub>3</sub> Addition on Hydroxyapatite Fabricted by Powder Metallurgy

Yttria-stabilized zirconia (YSZ) becomes popular alternative to alumina (Al2O3) especially for hard tissue applications. Both zirconia and alumina own their good biocompatibility due to chemical inertness in body environment. Considering the bioactive of hydroxyapatite (HAP) will allow interfacial bond formation, it is desirable to combine the advantages of both materials, YSZ and Al2O3with HAP. Various amounts (30, 40, 50, 60 wt. % of YSZ-Al2O3)/10HAP of composites have been prepared by powder metallurgy method. Several tests have been conducted to determine the effect YSZ addition on physical, mechanical properties and the microstructure of composites. The results showed that density and compressive strength increased with increasing wt. % of YSZ. Microstructural characterization has been observed by scanning electron microscope (SEM) showed the presence of pores reduced slightly in increasing of wt. % of YSZ. The prepared YSZ-Al2O3/10HAP composite is expected as a potential candidate for biomedical application.

The Role of Mixed Conduction in W-WO3 Redox Kinetics

The tungsten - tungsten trioxide (W-WO3) materials system has recently shown excellent promise as a medium for grid level energy storage and for solar energy conversion. In both these applications the thermal energy transfer is accompanied by a redox reaction in the W-WO3 couple. For viability of this system as an energy storage medium, it is important to have facile redox kinetics that allows us to rapidly store and release energy. Facile kinetics are also required in the utilization of this system in solar syngas production. In this paper we show that the addition of an ionic conducting phase, namely yttria stabilized zirconia (YSZ) greatly enhances the redox kinetics of the W-WO3 couple. Specifically, the reduction kinetics of the WO3-W reaction are facilitiated by the addition of YSZ. As a control experiment, a redox experiment with a filler material that is not an ionic conductor did not show such an enhancement in the kinetics. Chemical reaction rates were determined by transient thermogravimetry, and the data were analyzed using relevant kinetic and transport theory.