- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Fabrication of fine-grained undoped Y2O3 transparent ceramic using nitrate pyrogenation synthesized nanopowders
摘要： Y2O3 ceramic is a promising optical material for mid-infrared (IR) windows and domes. Improvements in the mechanical and thermal performance of this material have become urgent if it is to perform adequately under extreme conditions. Herein, Y2O3 nanopowders were produced through the nitrate pyrogenation method. The final Y2O3 transparent ceramics were fabricated with a hybrid sintering method combining low temperature presintering and a subsequent hot isostatic pressing (HIP) treatment. The synthesis of nanopowders and the fabrication of the final ceramic products were investigated in detail. The Y2O3 ceramic sample that was presintered at 1350 °C provided the optimum microstructure for HIP treatment and resulted in an average grain size of 0.5 μm. Owing to the reduced grain size, the flexure strength and Vickers hardness of the sample were improved to 180 MPa and 8.4 GPa, respectively. Furthermore, the achieved pure Y2O3 ceramic demonstrated an excellent thermal conductivity at high temperature.
关键词： Nanopowders,Y2O3,Nitrate pyrogenation,Fine-grained transparent ceramic
更新于2025-09-23 15:23:52
-
Peculiarities of the dielectric properties of ternary 0.5(Y0.1Zr0.9O2) – 0.5(0.6SrTiO3 – 0.4BiScO3) ceramic system
摘要： Ceramic samples of ternary 0.5(Y0.1Zr0.9O2) – 0.5(0.6SrTiO3 – 0.4BiScO3) system consisting of individual Y0.1Zr0.9O2 and 0.6SrTiO3 – 0.4BiScO3 subsystems were synthesized via solid-state processing techniques. By XRD analysis, a coexistence of tetragonal P42/nmc phase related to the Y0.1Zr0.9O2 subsystem, and cubic Pm m3? and tetragonal P4mm phases associated with the 0.6SrTiO3 – 0.4BiScO3 subsystem was found. A deviation of real composition from nominal one for both Y0.1Zr0.9O2 and SrTiO3 – BiScO3 subsystems due to Sc substituting for Zr in the Y0.1Zr0.9O2 subsystem and, vice versa, Zr substituting for Sc in the SrTiO3 – BiScO3 subsystem was also observed. Peculiarities of the dielectric properties related to both di?use ferroelectric phase transition and dielectric relaxation processes were found and analyzed in comparison with the dielectric properties of two-component 0.6SrTiO3 – 0.4BiScO3 system. It was found that the di?use phase transition in ternary system, ?rstly, shifts to lower temperatures and, secondly, has a less degree of di?useness as compared to two-component system. Such kind of behavior could be attributed to a di?erence of ionic radii of ions Zr4+ and Sc3+. Dielectric relaxation processes associated with the O2- ions migration were observed within temperature 500–800 K for both ternary and two-component systems. Two dielectric relaxation processes related to the Y0.1Zr0.9O2 and 0.6SrTiO3 – 0.4BiScO3 subsystems were found in ternary system, whereas one dielectric relaxation process was observed in two-component system. The activation energies for the dielectric relaxation processes were estimated as ~ 1.3 eV and ~ 0.9 eV for Y0.1Zr0.9O2 and 0.6SrTiO3 – 0.4BiScO3 subsystems, respectively, for ternary system, and ~ 0.75 eV for two-component system.
关键词： Dielectric relaxation process,Two-component ceramic system,Y0.1Zr0.9O2 and 0.6SrTiO3 – 0.4BiScO3 subsystems,Ternary ceramic system,Di?use phase transition
更新于2025-09-23 15:22:29
-
[IEEE 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - Xuzhou (2018.7.21-2018.7.24)] 2018 Cross Strait Quad-Regional Radio Science and Wireless Technology Conference (CSQRWC) - The Design and Experimental Verification of Broadband Absorbing Structure Combined by A1<inf>2</inf>O<inf>3f</inf>/ Al<inf>2</inf>O<inf>3</inf>Compositesand Metamaterials
摘要： With the aim to design a particular electromagnetic (EM) wave absorbing structure for broadband frequency used at high temperature, a multi-layer structure was proposed by combing the dielectric materials and square patch metamaterial. The absorbing structure was fabricated by precursor infiltration and pyrolysis technique and screen printing process. The computational and experimental results showed that a maximum reflection loss could be lower than ?7dB at 2-18GHz with a total thickness of 9mm. This effective enhancement on EM wave absorption property was believed to be a consequence of multi-layer and resonance effect induced by combining the traditional EM absorbing materials with metamaterial structure.
关键词： Electromagnetic wave absorption properties,Computation,Ceramic matrix composites
更新于2025-09-23 15:22:29
-
[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Improved Surface Flashover Characteristics of Ceramic Vacuum Interface by Surface Treatment
摘要： In this paper, influences of surface Cr2O3 coating treatment on ceramic vacuum interface under a long pulse-duration voltage are reported. The surface properties of the treated ceramics have been measured by SEM, LSCM and XRD methods. Compared with the original untreated ceramics, the treated ceramic has a smoother surface, a lower SEE coefficient and a lower surface resistivity. As a result, a higher surface flashover voltage has been obtained. The surface treatment is an easy and convenient method to improve surface flashover characteristics of ceramic vacuum interface under a long pulse-duration high voltage.
关键词： surface treatment,ceramic vacuum interface,surface flashover,secondary electron emission,Cr2O3 coating
更新于2025-09-23 15:22:29
-
Rheological and Curing Behavior of Acrylate-Based Suspensions for the DLP 3D Printing of Complex Zirconia Parts
摘要： The present study demonstrates the possibility of fabricating zirconia parts with a complex shape and internal architecture using a low-cost stereolithography-based technique. One of the critical steps in ceramics stereolithography is the preparation of a photo-curable slurry with properties that fulfil specific requirements, such as having a low viscosity, high solids loading and appropriate curing characteristics. Slurries with different acrylic monomers and ceramic fillers were studied concerning their rheological and curing behavior. New formulations based on mono- and tri-functional acrylic monomers revealed the following excellent rheological properties: The viscosity of the mono-/tri-acrylate-based slurry with 75 wt.% of zirconia was 1.6 Pa·s at 30 s?1. Zirconia stabilized with 3 mol.% yttria was found to be more favorable than zirconia with 8 mol.% yttria for slurry preparation, because of its lower surface area and higher tapped density. It was shown that the cure depth of the suspensions was suitable for printing objects with a 50 μm layer thickness, good interlayers connection and surface finishing.
关键词： ceramic,digital light processing,additive manufacturing,zirconia,stereolithography
更新于2025-09-23 15:22:29
-
Processing and Characterization of ZrO<sub>2</sub>-TiO<sub>2</sub> Porous Films by Dip Coating for Application as Environmental Sensors
摘要： The main objective of this work is to study and characterize porous ZrO2-TiO2 films on alumina substrates that will be used for the production of porous ceramic sensors for the monitoring of air humidity in environments subject to the incidence of solar radiation. For the production of the films the dip coating technique was adopted. A viscosity study was performed to obtain stable suspensions of ZrO2-TiO2 in isopropyl alcohol with the para-aminobenzoic acid deflocculant (PABA), at concentrations of 10, 12.5 and 15% by weight of solids. X-ray diffraction (XRD) characterizations were performed for the identification of crystalline phases, morphological analyzes by scanning electron microscopy (SEM) and chemical analyzes by energy dispersive X-ray spectroscopy (EDS). The results allowed to determine the minimum value of viscosity and amount of deflocculant to stabilize the suspension. The sensor elements in the form of 1:1 (weight) ZrO2 - TiO2 porous films showed great potential to be used as sensors for the measurement of relative humidity the size and distribution of desirable pores in the porous film for application as moisture sensors was obtained with 12.5 and 15 % by weight ZrO2-TiO2
关键词： deflocculant,sensors,porous ceramic films,viscosity
更新于2025-09-23 15:22:29
-
Influence of C2H2 Flows on Microstructure and Corrosion Resistance of TiCN Films Doped with Carbon Atoms
摘要： Nanosized TiCN/TiN films were deposited on AZ31 by reactive magnetron sputtering under different acetylene flows. The microstructures of obtained films were characterized, and their corrosion behaviors were also investigated. The films doped with carbon atoms under different acetylene flows own different structures and grain sizes. The grain size decreased to some extent, and the film structure changed from polycrystalline to nanocrystalline, with an increase of C2H2 flow. The surface morphology also changed from rough to smooth, with an increase of C2H2 flow. The Tafel curves and electrochemical impedance spectroscopy (EIS) demonstrated that the composite films could greatly improve the corrosion resistance of bare substrates in a 3.5% NaCl solution, and the films' corrosion resistance is different, owing to their different structures and grain sizes.
关键词： acetylene flows,ceramic coatings,microstructure,vacuum,corrosion behavior
更新于2025-09-23 15:22:29
-
Microwave transmission performance of fused silica ceramics in microwave high-temperature heating
摘要： Compared with traditional heating methods, microwave heating is widely used in many industrial heating fields because of its advantages, such as material-selective heating, volumetric heating and high-efficiency heating. However, previous studies have shown that the heating mode depends on the transmission performance of refractory insulation materials. In this study, a commonly used refractory material (fused silica ceramics) for microwave heating was studied, according to the law of electromagnetic wave propagation in a single-layer plate, the power transmission coefficient (PTC) of the material at different thickness, temperature and frequency (915 MHz and 2360 MHz) was calculated and analysed, in order to design the refractory structure which has good microwave transmission performance in the whole microwave heating process. The results show that the transmission performance of fused silica ceramics fluctuates regularly with increasing thickness, and there are several microwave transmission peaks in the PTC patterns, the thicknesses corresponding to the transmission peaks at frequency 2360 MHz are in order 0.033 m, 0.065 m and 0.098 m; as the temperature increases, the position of the transmission peaks will shift to a smaller thickness, the transmission performance of fused silica ceramics decreases slightly with increasing temperature. Comparing the transmission performance of mullite, alumina (Al2O3) and fused silica ceramics, it was found that the fused silica ceramics have excellent transmission properties; especially it is at high temperature. The results of this study can provide guidance for the selection of refractory structure materials and sizes as well as the optimization of heating process parameters in high-temperature microwave heating.
关键词： A. Microwave heating,D. Transmission performance,B. Fused silica ceramic,C. High temperature wave transmitting material
更新于2025-09-23 15:22:29
-
Influence of Structure Modification of Silicon Carbide Materials on Their Dynamic Properties
摘要： SiC ceramic materials were prepared both by reactive and liquid-phase sintering. Structure was modified during preparation by introducing reinforcing SiC-filaments and by synthesizing grains self-reinforcing the structure. The armor-protection capacity was determined by estimating the bullet penetration delay time.
关键词： reinforced materials,bullet resistance of the ceramic material,cracking resistance,liquid-phase sintered silicon carbide (LPS-SiC),reaction-sintered silicon carbide (SiSiC)
更新于2025-09-23 15:21:21
-
Effect of dissolved silica on photocatalytic water purification with a TiO2 ceramic catalyst
摘要： If photocatalytic water purification technologies will find practical applications, the impact of total dissolved solids in the source water on the activity of the photocatalyst must be evaluated. In this study, we evaluated the effects of SiO3 2? in water on a TiO2 ceramic photocatalyst; specifically, we determined the effects of SiO3 2? on the rate of photocatalytic degradation of formic acid (as a model contaminant) and on the rate of photocatalytic inactivation of Escherichia coli in an aqueous solution. Both the rate of formic acid degradation and the sterilization rate decreased with increasing SiO3 2? concentration. On the other hand, at a given SiO3 2? concentration, the activity of the photocatalyst did not decrease over the course of 120 h, and the surface structure of the photocatalyst did not change (i.e., no precipitate formed on the surface). The decreases in photocatalytic activity due to the presence of SiO3 2? could be recovered by flushing the experimental apparatus with distilled water. These results show that the reason for the lower photocatalytic activity in the presence of SiO3 2? than in its absence was due to adsorption of SiO3 2? onto the surface of the TiO2 photocatalyst and that SiO3 2? adsorption was an equilibrium process in water.
关键词： TiO2 ceramic photocatalyst,SiO3 2?,Photocatalysis,formic acid,E. coli
更新于2025-09-23 15:21:21