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31.
Xiaoqing Si Jian Cao Sheng Liu Xiaoguo Song Junlei Qi Yongxian Huang Jicai Feng 《International Journal of Hydrogen Energy》2018,43(5):2977-2989
A novel low-temperature sealing method was developed to seal solid oxide fuel cells. The 3D Ni nanosheet array was pre-fabricated on faying surfaces of Crofer22APU interconnect and NiO-YSZ anode-support. Then it was covered with Au film without changing its morphology. This special nanostructure improved sintering efficiency between Ag nanoparticles and substrates. A dense joint was obtained at the low-temperature between 250 °C–300 °C. This method effectively avoided the oxidation of interconnect during sealing. When joints were sealed at 300 °C, the shear strength reached 16 MPa. The fracture was mainly located in the central Ag layer, presenting a significant plastic deformation. Due to the effective protection of Ni layer, joints also possessed excellent oxidation resistance in oxidizing atmosphere at 800 °C for 400 h. After high-temperature oxidation, the shear strength was increased to 23 MPa, revealing an increasement of 43.8% compared with the as-sealed condition (16 MPa). This sealing method has great potential in sealing solid oxide fuel cells. It also can be extended to seal other energy-conversion devices. 相似文献
32.
Corrosion of a salt-coated Ni-superalloy has been studied at 900°C under a wet air and sulfur vapor ambient. The corrosion thickness, after an incubation of ~60 hr, linearly increases with the corrosion time t and the onset of surface spallation occurred at t ≈ 60 hr. The corroded layer consists of a corrosion front dominated by Cr3S4 scales and linear precipitate structures, an inner corrosion layer dominated by Ni3S2 and NiO, and an outer corrosion layer dominated by Al2O3 networks surrounding the Ni3S2 and/or NiO scale structures. The corrosion mechanism is discussed based on the coexistence of H2O, sulfur, and oxygen. 相似文献
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34.
《中国稀土学报(英文版)》2020,38(4):384-394
In this paper,CeO_2 with a pore size of 2-4 nm was synthesized by hydrothermal method.The CeO_2 modified graphene-supported Pt catalyst was prepared by the microwave-assisted ethylene glycol reduction chloroplatinic acid method,and the effect of the addition of CeO_2 prepared by different hydrothermal reaction time on the catalytic performance of Pt-based catalysts was investigated.The microstructures of CeO_2 and catalysts were characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),specific surface area and pore size analyzer(BET),scanning electron microscopy(SEM) and electron spectroscopy(EDAX),transmission electron microscopy(TEM),and the catalysts electrochemical performance was tested by electrochemical workstation.The results show that the catalytic performance of the four catalysts with CeO_2 is better than that of the catalyst without CeO_2.Adding CeO_2 with a specific surface area of 120.15 m~2/g prepared by hydrothermal reaction time of 39 h to Pt/C synthesis catalyst,its electrocatalytic performance,stability and resistance to poisoning are the best.The electrochemical active surface area is 102.83 m~2/g,the peak current density of ethanol oxidation is 757.17 A/g and steady-state current density of 1100 s is 108.17 A/g which shows the lowest activation energy for ethanol oxidation reaction.When the cyclic voltammogram is scanned for 500 cycles,the oxidation peak current density retention rate is 87.74%. 相似文献
35.
This study investigated the oxidation kinetics of silicon-containing steel at 1150–1300 °C using a Simultaneous Thermal Analyzer under atmospheric conditions similar to that of an industry reheating furnace. There is a critical time point for the oxidation kinetics at an oxygen concentration of 4·0 vol.-%., following which the oxidation rate constant increases with the increasing oxidation temperature. The model coefficient A in the kinetic oxidation equation was found to be constant. However, before the critical time point, the oxidation rate constant remained unchanged; the model coefficient A decreased with the increasing temperature. Therefore, the kinetic model of silicon-containing steel for isothermal oxidation was observed to be a modified one on the basis of the experimental data. In addition, the critical time point was prolonged with the increasing isothermal oxidation temperature. Moreover, the oxidation activation energy of the tested silicon-containing steel was 366·16 kJ mol?1. 相似文献
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37.
热后硬孔攻丝螺纹变形量小、尺寸稳定、强度高。该工艺方法对刀具强度要求较高,使用普通高速钢丝锥和螺纹铣刀加工时,普通高速钢丝锥无法承受热后硬孔攻丝所产生的大扭矩而频繁折断,报废率较高,同时螺纹铣刀成本高,不适合大批量生产。针对热后硬孔攻丝工艺复杂、成本高的问题,专门设计了硬孔攻丝用高性能先端丝锥,解决硬孔攻丝难题,并与其他种类丝锥进行了切削力对比。 相似文献
38.
During present investigations, an attempt was made to understand the effect of mean stress and oxidation on low cycle fatigue (LCF) behaviour of CM 247 DS LC alloy at T?=?850°C. A significant reduction in fatigue life was observed during LCF tests conducted at strain ratio (R) of 0 as compared to R?=??1. Reduction in fatigue life is attributed to the synergistic effect of mean stress, oxidation and the expanding precipitates within the grain boundaries which imparts high stresses at the grain boundary leading to the intergranular cracking. Additionally, to account the effect of mean stress on fatigue life of the alloy CM 247 DS LC empirical relations developed by Smith–Watson–Topper (SWT) and Morrow were used. 相似文献
39.
Ozone (O3) chemistry is thought to dominate the oxidation of indoor surfaces. We consider the hypothesis that reactions taking place within indoor boundary layers result in greater than anticipated hydroxyl radical (OH) deposition rates. We develop models that account for boundary layer mass‐transfer phenomena, O3‐terpene chemistry and OH formation, removal, and deposition; we solve these analytically and by applying numerical methods. For an O3‐limonene system, we find that OH flux to a surface with an O3 reaction probability of 10?8 is 4.3 × 10?5 molec/(cm2 s) which is about 10 times greater than predicted by a traditional boundary layer theory. At very low air exchange rates the OH surface flux can be as much as 10% of that for O3. This effect becomes less pronounced for more O3‐reactive surfaces. Turbulence intensity does not strongly influence the OH concentration gradient except for surfaces with an O3 reaction probability >10?4. Although the O3 flux dominates OH flux under most conditions, OH flux can be responsible for as much as 10% of total oxidant uptake to otherwise low‐reactivity surfaces. Further, OH chemistry differs from that for ozone; therefore, its deposition is important in understanding the chemical evolution of some indoor surfaces and surface films. 相似文献
40.
Wenhui Zhu Haizhen Huan Ying Bu Xuepeng Li David Shiuan Jianrong Li Xiaotao Sun 《International Journal of Food Science & Technology》2019,54(6):2159-2168
Protein oxidation is considered as an important issue in food preservation process. In the present study, the potential influence of protein oxidation on water holding capacity and protein structure of jumbo squid (Dosidicus gigas) mantle was investigated. After the hydroxyl radical oxidation, it was found that the carbonyl, surface hydrophobicity and dityrosine content of myofibrillar protein significantly increased (P < 0.05), while the content of total sulphydryl decreased significantly (P < 0.01). Meanwhile, the fluorescence intensity of squid was weakened, and the maximum absorption peak of fluorescence red shift as the H2O2 concentration increased. The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) showed that not only the protein cross-linking but also degradation could have occurred. The content of α-helix decreased, the content of β-sheet, β-turn and the unordered structures increased after oxidation. In addition, oxidation resulted in a decrease in water holding capacity. Taken together, oxidation resulted in the damage of the myofibrillar structure, the increase in muscle loss rate and the decrease in water holding capacity. 相似文献