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51.
《Ceramics International》2019,45(16):20033-20039
Ceramic dual-phase oxygen transport membranes with the composition of 60 wt% Ce0.9Pr0.1O2-δ-40 wt%Pr0.6Sr0.4Fe1-xAlxO3-δ (x = 0.05, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1.0) (60CPO-40PSF1-xAxO) based on 60Ce0.9Pr0.1O2-δ-40Pr0.6Sr0.4FeO3-δ doped Al was successfully synthesized through a modified Pechini method. Crystal structure, surface microtopography and oxygen permeability are investigated systematically. The cell parameters of perovskite phase first increased and then decreased with the increase of Al content, which is related to the radius of the Al3+ and the formation of impurity phase. As x ranges from 0.1 to 0.8, the oxygen permeability of the materials first increases and then decreases, and the maximum value of oxygen permeation rate for 60CPO-40PSF1-xAxO membranes with 0.4 mm thickness at 1000 °C is 1.12 mL min−1 cm−2 when x = 0.4. XRD measurements revealed high temperature stability and CO2-tolerant property of the dual-phase composites. The partial replacement of Fe3+/Fe4+ by Al3+ causes the material not only to exhibit good stability, but also to increase the oxygen permeability of the membranes. 相似文献
52.
《Journal of the European Ceramic Society》2023,43(14):6337-6348
A novel series of ZnAl2O4:Eu3+ aerogels (ZAE) and mullite ceramic phase reinforced ZnAl2O4:Eu3+ aerogels (MZAE) with high fluorescence thermal stability have been firstly synthesized for the encapsulation of high-power optical devices. However, due to the intrinsic structural brittleness of the aerogel, the structure of ZAE tends to collapse during the heat treatment and the fluorescence performance falls short of expectations. To this end, we propose a simple and effective strategy to enhance the structural rigidity of fluorescent aerogels by introducing the mullite ceramic phase into the network structure of ZAE. This can effectively suppress the agglomeration of Eu3+ caused by the collapse of the structure during the heat treatment, thus enhancing the optical properties of the aerogel. Compared with ZAE, MZAE has higher fluorescence thermal stability. The fluorescence intensity of MZAE at 498 K is still 75 % of that at 298 K, and the chromaticity shift is only 22 × 10−3. 相似文献
53.
《Ceramics International》2016,42(7):8140-8150
To develop a high emissivity coating on the low thermal conductivity ZrO2 ceramic insulation for reusable thermal protective system, the MoSi2–ZrO2–borosilicate glass multiphase coatings with SiB6 addition were designed and prepared with slurry dipping and subsequent sintering method. The influence of SiB6 content on the microstructure, radiative property and thermal shock behavior of the coatings has been investigated. The coating prepared with SiB6 included the top dense glass layer, the surface porous coating layer and the interfacial transition layer, forming a gradient structure and exhibiting superior compatibility and adherence with the substrate. The emissivity of the coating with 3 wt% SiB6 addition was up to 0.8 in the range of 0.3–2.5 μm and 0.85 in the range of 0.8–2.5 μm at room temperature, and the “V-shaped grooves” surface roughness morphology had a positive effect on the emissivity. The MZB-3S coating showed excellent thermal shock resistance with only 1.81% weight loss after 10 thermal cycles between 1773 K and room temperature, which was attributed to the synergistic effect of porous gradient structure, self-sealing property of oxidized SiB6 and the match of thermal expansion coefficient between the coating and substrate. Thus, the high emissivity MoSi2–ZrO2–borosilicate glass coating with high temperature resistance presented a promising potential for application in thermal insulation materials. 相似文献
54.
以氟化铵为矿化剂、四丙基溴化铵为模板剂,在负载晶种的钇稳定氧化锆(YSZ)中空纤维支撑体表面合成了MFI型分子筛膜,并用于乙醇/水的分离;系统考察了氟硅比(nNH4F/nSiO2)、合成时间等条件对膜分离性能的影响,在nNH4F/nSiO2为0.8、合成时间为8 h下合成出高性能膜,其通量达8.2 kg·m-2·h-1、乙醇/水分离因子为47;同时研究了MFI型分子筛膜在乙醇/水体系中的分离稳定性,揭示出该方法所合成膜表面无Si-OH,从而避免了Si-OH与乙醇反应而带来膜分离性能的下降. 相似文献
55.
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57.
《Parallel Computing》2004,30(5-6):611-628
We present in this work a wide spectrum of results on analyzing the behavior of parallel heuristics (both pure and hybrid) for solving optimization problems. We focus on several evolutionary algorithms as well as on simulated annealing. Our goal is to offer a first study on the possible changes in the search mechanics that the algorithms suffer when shifting from a LAN network to a WAN environment. We will address six optimization tasks of considerable complexity. The results show that, despite their expected slower execution time, the WAN versions of our algorithms consistently solve the problems. We report also some interesting results in which WAN algorithms outperform LAN ones. Those results are further extended to analyze the behavior of the heuristics in WAN with a larger number of processors and different connectivities. 相似文献
58.
《Ceramics International》2019,45(15):18924-18930
Composite ceramic membrane is one of the most attractive concepts which combines the advantages of different phases into a single membrane matrix. Recently, the reported significant increased oxygen surface kinetics on the Perovskite/Ruddlesden-Popper composite system because of the formation of novel and fast oxygen transport paths along the hetero-interface has been implanted into the oxygen permeation membrane system. In this work, a novel La0.6Sr0.4Co0.2Fe0.8O3-δ-(La0.5Sr0.5)2CoO4+δ (LSCF-LSC) composite hollow fiber membrane is synthesized with oxygen permeation flux of 4.52 mL min−1 cm−2 at 950 °C. It presents round 4 times and 2.3 times of that of the single LSCF membrane and LSC-coated LSCF membrane at 900 °C. For better comparison, (La0.576Sr0.424)1.136Co0.3Fe0.7O3-δ (LSCF-new) is prepared based on the composition of LSCF-LSC composite. The enhanced oxygen permeability was further investigated through electrochemical impedance spectroscopy (EIS) measurements. We also confirm that LSCF-LSC shows significantly lower area specific resistance (ASRs) for LSCF-LSC|Ce0.8Sm0.2O1.9 (SDC)|LSCF-LSC symmetrical cell relative to other symmetrical cells. This novel LSCF-LSC composite membrane also presents high CO2 tolerance, with stable oxygen permeation fluxes round 2.6 mL min−1 cm−2 at 900 °C for 100 h. 相似文献
59.
《Ceramics International》2019,45(11):13747-13760
TiO2-rGO nanocomposite coatings were obtained by electrophoretic deposition (EPD) technique of TiO2 nanoparticles and graphene oxide (GO) on stainless steel substrate. First, GO particles were synthesized using a modified Hummers' method. GO was reduced electrochemically to form a coating in the presence of nano-sized TiO2 particles. The influences of different parameters such as GO concentration, coupling co-electro-deposition parameters (electrophoretic duration and voltage) on thickness, surface morphology and, corrosion behavior of the as-synthesized TiO2-rGO nanocomposite coatings were systematically surveyed. The morphology and microstructure were investigated by field emission scanning electron microscopy (FE-SEM), Raman spectra and X-ray diffraction (XRD) techniques. Atomic force microscopy (AFM) was harnessed to evaluate the topography of the as-prepared GO powder. The bonding characteristics of as-synthesized and as-reduced GO were examined after deposition, by Energy Dispersive Analysis of X-Ray (EDX) and Fourier-transform infrared spectroscopy (FT-IR). Corrosion behavior of coatings and that of the pure TiO2 layer were evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques (by applying potentiodynamic polarization spectroscopy (PDS)). Detailed SEM studies showed that increasing EPD voltage brings about a coating with increased porosity and microcracks with higher thickness. In addition to that, the presence of rGO reduced corrosion current density (icorr) and shifted corrosion potential (Ecorr) toward more noble values in 3.5% NaCl at room temperature. Also, Analyses revealed that the optimum electrophoretically synthesized coating was obtained at GO concentration of 1 g/L, 30 V and 30 min at room temperature. The corrosion current density of the corresponding coating was remediated up to 0.2 μA cm−2, which means an anti-corrosion ability of about 30 times compared to TiO2-coated and bare 316L stainless steel. The results of impedance spectroscopic studies demonstrated that this coating renders as a barrier layer and resistance increased from 2.95 KΩ cm2 for TiO2-coated layer to 10.49 KΩ cm2 for the optimized layer. 相似文献
60.
《Ceramics International》2019,45(16):19888-19894
Porous solid-state-sintered SiC (S–SiC) membrane supports were successfully fabricated by pressureless sintering at 2150 °C in argon, using fine and coarse graded SiC powders as the main starting material. There were uniformly distributed and fully interconnected pores in as-acquired S–SiC membrane supports, accompanied with similar apparent porosities for all of them. When increasing the size of coarse SiC powder, their average pore sizes were distinctly enlarged from ∼1.6 μm to ∼2.3 μm, which significantly enhanced their nitrogen permeability from 0.9 × 10−13 m2 to 2.6 × 10−13 m2. Moreover, S–SiC membrane supports possessed outstanding flexure strengths of 134.1 ± 21.3 MPa at room temperature and 88.7 ± 8.4 MPa at 1000 °C owing to strong interface bonding between SiC grains. Compared with the traditional SiO2 -bonded and mullite-bonded SiC supports, S–SiC membrane supports presented their great superiority in high-temperature flexure strength as well as acid and alkali corrosion resistance, which permitted them to be potentially applied in high-temperature and strongly corrosive environments. 相似文献