Thickness Of Yttria-stabilized Zirconia Research Articles

Using Planar Metamaterials to Design a Bidirectional Switching Functionality Absorber—An Ultra-Wideband Optical Absorber and Multi-Wavelength Resonant Absorber

This study aimed to investigate a bidirectional switching functionality absorber, which exhibited an ultra-wideband characteristic in one direction, while in the other direction it demonstrated the absorption of three different resonant wavelengths (frequencies). The fully layered planar structure of the absorber consisted of Al2O3, Zr, yttria-stabilized zirconia (YSZ), Zr, YSZ, Al, YSZ, and Al. The simulations were conducted using the COMSOL Multiphysics® simulation software (version 6.1) for analyses, and this study introduced three pivotal innovations. Firstly, there had been scarce exploration of YSZ and Zr as the materials for designing absorbers. The uses of YSZ and Zr in this context were a relatively uncharted territory, and our research endeavored to showcase their distinctive performance as absorber materials. Secondly, the development of a planar absorber with multifunctional characteristics was a rarity in the existing literature. This encompassed the integrations of an ultra-wideband optical absorber and the creation of a multi-wavelength resonant absorber featuring three resonant wavelengths. The design of such a multi-wavelength resonant absorber holds promise for diverse applications in optical detection and communication systems, presenting novel possibilities in related fields. Lastly, a notable discovery was demonstrated: a discernible redshift phenomenon in the wavelengths of the three resonant peaks when the thickness of YSZ, serving as the material of resonant absorber layer, was increased.

Effect of Top-Coat Thickness and Interface Fluctuation on the Residual Stress in APS-TBCs

This study focused on the numerical simulation of the distribution of residual stress in yttria-stabilized zirconia (YSZ) coatings prepared with atmospheric plasma spraying (APS). We particularly investigated the stress distribution around the interface between the top coat and bond coat. During thermal spray deposition, droplets and particles deposit on the substrate in a complex manner, causing interface waviness and non-uniform stress distribution. Therefore, residual stress is an important consideration when preparing thermal barrier coatings (TBCs). Residual stresses directly affect the performance of bond coats (BCs) and ceramic top coats (TCs). To accurately evaluate residual stress, we considered interface waviness and the thickness of the ceramic top coat and conducted a detailed analysis of stress distribution. The results show that compressive stress exists at the TC/BC interface, which may be caused by the mismatch in the thermal expansion coefficient between the YSZ top coat and the substrate, potentially leading to coating delamination. Moreover, the residual stress at the TC/BC interface significantly increases with an increasing YSZ thickness. When the top-coat thickness exceeds 300 μm, stress concentration and failure of the coating are likely to occur. Meanwhile, the optimized thermal spray experiment results confirm that the residual stress at the BC/YSZ interface of the thermal barrier coating is tensile stress, with a maximum value of 155 MPa, which is consistent with the finite element calculation results. Furthermore, the failure modes of TBCs with rough interface conditions are discussed in detail. Our research provides important guidance for TBC design and optimizing their performance.

Characterization and Performance Evaluation of Yttria-Stabilized Zirconia (YSZ) Thickness on ZnO Nanorods-Based Photoelectrochemical Cell

Photoelectrochemical cell (PEC) has the same working principle as solar cell which convert solar energy into electricity. PEC consists of photoanode, electrolyte, and counter electrode, where electrolyte plays an important role in determining PEC performance. Yttria-stabilized zirconia (YSZ) is the most suitable electrolyte used due to its high ionic conductivity and chemically stable. In this study, YSZ was deposited to ZnO Nanorods (NRs) by doctor blade method with thickness variation of 100 μm (PEC10) and 120 μm (PEC12). X-ray diffraction (XRD), scanning electron microscope (SEM), and UV-Vis spectroscopy were used to distinguish the phase, morphology, and band gap of the formed materials, respectively. Moreover, I-V test was also conducted to evaluate the performance of the fabricated PEC with different YSZ thickness. SEM image confirmed the deposition thickness of YSZ layer on NRs which formed rough and irregular interface due to grain boundary fusion of YSZ and NRs. In addition, there is little difference XRD pattern from PEC10 and PEC12 which shows ZnO and YSZ peaks with peak shifting observed. Meanwhile, slightly difference noticed on band gap value where PEC10 has 3.25 eV and PEC12 has 3.58 eV. Even though, the characteristic of PEC10 and PEC12 is similar, the I-V test shown a significant difference of solar efficiency where PEC10 has higher efficiency of about 0.328% than PEC12. This difference is contributed by smaller grain size which has higher specific surface area and porosity. Based on this study, the thickness of electrolyte layer YSZ doesn’t affect the basic characteristic of PEC but affect the efficiency of PEC significantly.

Cracking evolution of atmospheric plasma-sprayed YSZ thermal barrier coatings subjected to isothermal heat treatment

It is known that residual stress is the main factor causing the final failure of thermal barrier coatings (TBCs). However, it is still unclear how the stress governs the cracking sequence. In this paper, atmospheric plasma-sprayed (APS) 8 wt% yttria-stabilized zirconia (YSZ) TBCs were subjected to isothermal heat treatment at 1050 °C for different time. The cracking evolution and the underlying mechanical mechanisms for cracking were investigated. Residual stress distribution through the YSZ thickness was evaluated using Raman spectroscopy. It is found that, after thermal exposure, the in-plane residual compression in the top-coat (TC) near the TC/thermally grown oxide (TGO) interface increases as the TGO thickens, inducing tensile stresses normal to the interface in the TC close to the undulation crests. A spherical analytical model is used to evaluate this tensile stress, and the result shows that it rises with the TGO growth. This normal tensile stress is the driving force for cracking of TBCs. Cracking parallel to the TGO/TC interface first initiates in the TC near the interface, and then coalesces with the cracks within the TGO and at the bond-coat (BC)/TGO interface, leading to the final delamination. Because TC has a relatively low fracture toughness, the delamination trajectory is primarily in the TC near the TGO/TC interface and along the pathway that contains inter-splat cracks, pores and weak splat boundaries. The results indicate that the large in-plane compressions play a significant role in the cracking evolution of TBCs because they induce normal tensile stress in the TC or at the TGO/BC interface. A cracking pattern dominated by the stress evolution is established in this work and it will provide an informed basis for improving the durability of APS-TBCs.

The sintering behavior of plasma-sprayed YSZ coating over the delamination crack in low temperature environment

The sintering behavior of plasma-sprayed yttria-stabilized zirconia (YSZ) coating over the delamination crack and its influence on YSZ cracking were investigated via gradient thermal cycling test and finite element model (FEM). The gradient thermal cycling test was performed at a peak surface temperature of 1150°C with a duration of 240s for each cycle. A three-dimensional model including delamination cracks with different lengths was employed to elaborate the temperature evolution characteristics in YSZ coating over the delamination cracks. The temperature over the delamination crack increases linearly with the crack propagation, which continuously promotes the sintering of YSZ coating in the region. As a result, the YSZ coating over the delamination crack sinters dramatically despite of the low temperature exposure. Meanwhile, the temperature distribution difference in YSZ coating induces an nonuniform sintering along both free surface and thickness of YSZ coating. Correspondingly, the maximum vertical crack driving force locates at the YSZ free surface over the delamination crack center, which makes the vertical cracks generate in this region and propagate to the interface of YSZ /bond coat with YSZ further sintering. The vertical crack promotes the delamination crack propagation via accelerating the oxidation velocity of the bond coat. The influence of temperature rise on delamination crack propagation can be divided into two stages: the little contribution stage and the promotion stage. For the actual engine exposure to low temperature, the study of phase transformation of YSZ over the delamination crack is indeed needed because of an extended remarkable temperature rise period.

Conductivity of Yittria-Stabilized Zirconia Nanostructure Electrolyte for Solid Oxide Fuel Cell Application by Using RF Magnetron Sputtering

Yttria-stabilized zirconia (YSZ) thin films were deposited successfully using RF magnetron sputtering. The substrate had been used are sapphire glass. A pure ceramic of Zr-Y is synthesized and processed into a planar magnetron target which is reactively sputtered with an Argon-Oxygen gas mixture to form Zr-Y-O nanostructure. The aim of this research is to study the conductivity and roughness YSZ thin film by using RF magnetron sputtering by varying the temperature deposition parameter. By lowering the YSZ thin film into nanostructure would enable for SOFC to be operate at lower temperature below 400°C. The YSZ nanostructure were controlled by varying the deposition parameters, including the deposition temperature and the substrate used. The crystalline of YSZ structure at 100W and temperature 300°C. The surface morphology of the films proved that at 300°C temperature rate deposition showed optimum growth morphology and density of YSZ thin films. Besides, the high deposition subtrate temperature affected the thickness of YSZ thin film at 80nm by using surface profiler. A higher rate of deposition is achievable when the sputtering mode of the Zr-Y target is metallic as opposed to oxide. YSZ is synthesizing to obtain the optimum thin film for SOFC application.

Comparison of thermal insulation capability between conventional and nanostructured plasma sprayed YSZ coating on Ni3Al substrates

Conventional and nanostructured yttria-stabilized zirconia(YSZ) as thermal barrier coatings were directly deposited on Ni3Al intermetallic compound substrates without bond coating by atmospheric plasma spraying. The adherence, thermal insulation capability, microstructure, porosity and sintering resistance of these two kinds of coatings were studied. For the thickness of 150µm YSZ coating without bond coating, the temperature drop (∆T=98℃) of the nanostructured YSZ coating at 1200℃ increases by 50.8% compared with that of the conventional YSZ coating (∆T=65℃). It is shown that the nanostructured YSZ coating has higher thermal insulation capability than the conventional YSZ coating, which is mainly due to its special microstructure with more semi-molten particles (21.78±0.54%), higher porosity (8.81±0.35%) and better sintering resistance.

High-temperature stability of yttria-stabilized zirconia thermal barrier coating on niobium alloy—C-103

Thermal barrier coatings (TBCs) of yttria-stabilized zirconia (YSZ) of different thicknesses with an intermediate bond coat were deposited on C-103 Nb alloy using the air plasma spraying technique. The coatings were subjected to rapid infra-red (IR) heating (∼25°C s−1) up to ∼1250°C and exposed up to 100 s at this temperature with heat flux varying from 55 to 61 W cm−2. The TBCs were found to be stable and intact after the heat treatment. In contrast, at the same conditions, the uncoated C-103 alloy specimen showed extensive oxidation followed by weight loss due to spallation. A maximum temperature drop of ∼200°C was observed on the opposite side of the coated alloy with 600 μm YSZ coat; as against negligible temperature drop in case of bare alloy specimen. The temperature drop was found to increase with the coating thickness of YSZ. The coatings before and after IR heating were investigated by scanning electron microscopy, X-ray diffraction, electron probe microanalysis, microhardness and residual stress measurements in order to understand the effect of thermal shock on the properties of the TBC. On account of these high-temperature properties, YSZ coating along with the bond coat is expected to find potential thermal barrier coating system on niobium alloys for supersonic vehicles.

Thermal stability and effect of typical water gas shift reactant composition on H2 permeability through a Pd-YSZ-PSS composite membrane

This work comprises a study of hydrogen separation with a composite Pd-YSZ-PSS membrane from mixtures of H2, N2, CO and CO2, typical of a water gas shift reactor. The Pd layer is extended over a tubular porous stainless steel support (PSS) with an intermediate layer of yttria-stabilized-zirconia (YSZ). YSZ and Pd layers were incorporated over the PSS using Atmospheric Plasma Spraying and Electroless Plating techniques, respectively. The Pd and YSZ thickness values are 13.8 and 100 μm, respectively, and the Pd layer is fully dense. Permeation measurements with pure, binary and ternary gases at different temperatures (350–450 °C), trans-membrane pressures (0–2.5 bar) and gas composition have been carried out. Moreover, thermal stability of the membrane was also checked by repeating permeation measurements after several cycles of heating and cooling the system. Membrane hydrogen permeances were calculated using Sieverts' law, obtaining values in the range of 4·10−5–4·10−4 mol m−2 s−1 Pa−0.5. The activation energy of the permeance was also calculated using Arrhenius' equation, obtaining a value of 16.4 kJ/mol. In spite of hydrogen selectivity being 100% for all experiments, the hydrogen permeability was affected by the composition of feed gas. Thus, a significant depletion in H2 permeate flux was observed when other gases were in the mixture, especially CO, being also more or less significant depending on gas composition.

Oxygen-permeating zirconia membrane: The effect of thickness and surface coating

The oxygen flux of yttria-stabilized-zirconia (YSZ) was measured as a function of membrane thickness and surface coating, under controlled P O 2 gradient (permeate side: ∼3 × 10 −12 atm; feed side: 2 × 10 −12 to 2 × 10 −8 atm) in reducing atmosphere at 1600 °C. The oxygen flux was determined by measuring the change of CO 2 content in CO gas stream of permeate side with gas chromatograph. In order to study the effect of surface-exchange kinetics, YSZ membranes with or without LaCrO 3 coating were used. The oxygen flux increased with decreasing YSZ thickness from 0.7 mm to 0.2 mm. The oxygen flux was controlled by both the bulk diffusion and surface exchange kinetics. Permeation experiment was possible for the membrane as thin as 200 μm by a new experiment setup. Characteristic membrane thickness ( L C) which divides the bulk diffusion and surface-exchange limits was calculated as 0.365 mm. Based on this study, the increased permeation flux is expected for YSZ with different coating layer.

초전도 테이프 제작을 위한 니켈기판 상의 산화물 박막 증찰

High temperature superconducting coated conductor has a structure of <protecting layer>/<superconducting layer>/<buffer layer>/<metallic substrate>. The buffer layer consists of multi-layer, this study reports the deposition method and optimal deposition conditions of YSZ(Yttria-stabilized zirconia) layer which plays a important part in preventing the elements of substrate from diffusing into the superconducting layer. YSZ layer was deposited by DC reactive sputtering technique using water vapor for oxidizing deposited elements on substrate. To investigate optimal thickness of YSZ film, four YSZ/CeO<TEX>$_2$</TEX>/Ni samples with different YSZ thickness(130 nm, 260 nm, 390 nm, and 650 nm) were prepared. The SEM image showed that the surface of YSZ layer was getting to be rougher as YSZ layer was getting thicker and the growth mode of YSZ layer was columnar grain growth. After CeO<TEX>$_2$</TEX> layer was deposited with the same thickness of 18.3 nm on each four samples, YBCO layer was deposited by PLD method with the thickness of 300 nm. The critical currents of four samples were 0, 6 A, 7.5 A, and 5 A respectively. This shows that as YSZ layer is getting thicker, YSZ layer plays a good role as a diffusion barrier but the surface of YSZ layer is getting rougher.

RF-magnetron-sputtered heteroepitaxial YSZ and CeO 2/YSZ/Si(0 0 1) thin films with improved capacitance–voltage characteristics

Heteroepitaxial yttria-stabilized zirconia (YSZ) and CeO 2/YSZ thin films were prepared on Si(0 0 1) by radio frequency (RF)-magnetron sputtering using a combination of metal (Zr+Y), YSZ ceramic and CeO 2 ceramic targets. Optimal crystallinity and minimal surface roughness were obtained for a 2-nm thick layer of metallic (Zr+Y). For YSZ thin film, a considerably large threshold hysteresis (memory window) of approximately 2.2 V was observed in the capacitance–voltage characteristics. It was clarified that the memory window can be suppressed by decreasing the thickness of YSZ. The memory window of CeO 2(90 nm thick)/YSZ(5 nm thick) thin film was reduced to 0.4 V.

Effect of the Thickness of SiO2 under Layer on the Initial Stage of Epitaxial Growth Process of Yttria-Stabilized Zirconia (YSZ) Thin Film Deposited on Si(001) Substrate.

Epitaxial growth of yttria-stabilized zirconia (YSZ) thin films on Si(001) substrates containing SiO 2 layers of various thickness was in-situ monitored by reflection high-energy electron diffraction (RHEED). The in-plane lattice parameter of YSZ at the initial stage of the deposition (the thickness of YSZ was below 5 nm), was very close to that of the Si substrate when the thickness of SiO 2 was below 0.49 nm. The in-plane lattice parameter of YSZ was significantly decreased approaching that of bulk YSZ when the thickness of YSZ was over 5 nm. The relaxation of the lattice parameter was caused by the generation of misfit dislocations or regrowth of SiO 2 between the Si and YSZ interface. On the contrary, if the thickness of SiO 2 was between 0.68 and 1.1 nm, the epitaxial growth was also confirmed, however, the in-plane lattice parameter did not change with the thickness of YSZ. The reason for the change of this lattice relaxation with the thickness of SiO 2 was discussed.

Design and fabrication of coplanar YBCO structures on lithium niobate substrates

YBa/sub 2/Cu/sub 3/O/sub 7-/spl delta// (YBCO) with low RF losses has been successfully deposited onto lithium niobate (LNO) to improve the performance of electrooptic Mach-Zender modulators. Epitaxial, c-axis oriented superconducting YBCO thin films have been grown on X-cut LNO single crystals with a yttria-stabilized zirconia (YSZ) buffer layer by RF magnetron sputtering. This buffer layer is needed to obtain good superconducting properties of the YBCO grown. Numerical tools have been developed to analyze CPW structures based on YBCO/YSZ/LNO trilayers, and they indicate that YSZ thickness has to be kept to the minimum necessary for good YBCO growth. With this restriction, the RF losses of YBCO/YSZ/LNO samples have been measured. The results from these measurements are used to quantify the performance enhancement in a Mach-Zender modulator using YBCO electrodes.