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91.
In order to understand the relation between microstructure of superalloy powders and its solidification progress, the processing parameters are optimized during plasma rotating electrode processing (PREP). It was predicted from the results that the droplet velocities, droplet temperature, and fractional solidification with flight time about FGH95 superalloy droplet have been carried out based on Newtonian heat transfer formulation coupled with the classical heterogeneous nucleation and the specific solidification process. It has been found that the droplet dynamic and thermal behavior is strongly affected by the distribution of droplet diameters, the proportion of cooling atmosphere, but is relatively unaffected by the droplet superheat. 相似文献
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Tong Wei Bo Liu Lichao Jia Renhong Li 《International Journal of Hydrogen Energy》2021,46(48):24441-24460
SOFC (solid oxide fuel cell, SOFC) is recognized to be efficient green energy technology in the 21st century. However, when hydrocarbons are directly used as fuel, carbon deposition is easy to occur in Ni-based anode, thus losing electrochemical catalytic activity. Fuel pre-reforming is also called on-cell reforming of hydrocarbons, which has been a promising solution for alleviating the carbon deposition problem in cermet anodes to varying degrees. And the key factor is to find an efficient and stable fuel reforming catalyst. Perovskite oxides have stable structure, highly catalytic activity and adjustable thermal expansion coefficient for using on the cells, showing great potentials of application for fuel reforming. In this paper, we summarize the application of perovskite catalyst in CH4 fuel reforming based on the research of our group and other scholars, and puts forward the corresponding views and perspective, especially in perovskite catalyst with Ni exsolution. 相似文献
95.
Daniel Leidermark David AspenbergDavid Gustafsson Johan Moverare Kjell Simonsson 《Computational Materials Science》2012,51(1):273-280
Coarse grained superalloys are of large interest in high temperature applications, and can be found in e.g. gas turbine components, where great care must be given with respect to high temperature fatigue. Due to the large grain size, the material behaviour at e.g. sharp notches cannot be considered homogeneous. As a consequence, the fatigue behaviour is likely to expose a large variation. In order to numerically investigate this variation, a Monte Carlo analysis has been carried out by 100 FE-simulations of notched specimens, where placements and orientations of the grains were randomised. Furthermore, each grain was modelled as a unique single-crystal, displaying both anisotropic elastic and plastic behaviour and tension/compression asymmetry. The effect of randomness was investigated by the obtained dispersion in fatigue crack initiation life. It was concluded that the fatigue life behaviour of coarse grained nickel-base superalloys may show a considerable variation, which cannot be captured by one single deterministic analysis based on data for a homogenised material. Furthermore, the dispersion is of such a magnitude that it needs to be taken into account in industrial applications where highly stressed coarse grained materials are used. 相似文献
96.
Internal nitride dispersion strengthened superalloy is a new type of high performance superalloy for combustion chamber. The background and development of this alloy were firstly introduced. And then the microstructure and properties of NS163 which is a typical internal nitride dispersion strengthened alloy were investigated. The results show that the microstructure of NS163 is simple in the temperature range of 900??1250??, which is composed of austenite matrix and MC carbide. The recrystallization behavior of the cold- rolled sheet under the test condition was studied systematically. It is found that the solid solution temperature of the finished product should be 1200??, and after solid solution at 1200??, the sheet has 5 grade average grain size, excellent cold workability and low tensile strength at high temperature. The above results can help to optimize the microstructure of NS163 alloy sheet before nitriding and provide a basis for the evaluation of the strengthening effect of the alloy after internal nitriding. 相似文献
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The residual stress induced by laser shock processing and the thermal relaxation behaviors of residual stress in Ni-based alloy GH4169 were investigated by means of three-dimensional nonlinear finite element analysis. To study the effect of different given exposure time and different temperatures on residual stress in laser shock processing Ni-based alloy GH4169, Johnson–Cook material model was used in order to account for the nonlinear constitutive behavior. The influence of heating temperature and exposure time on the stress thermal relaxation was studied. It was concluded that stress relaxation mainly occured during the initial period of exposure, and the degree of relaxation increased as the temperature risen. The results would provide a theoretical basis for controlling the laser shock processing and guiding subsequent experiments. 相似文献
100.
《International Journal of Hydrogen Energy》2022,47(2):984-992
The rational design and preparation of bifunctional electrocatalysts with pleasant oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance is crucial for extensive commercial applications of rechargeable Zn–air batteries (ZABs). Herein, we report a simple method to obtain multi-metal (Fe, Ni, Zn) embedded in N-doped carbon sheets entangled with carbon nanotubes (CNTs) as superior oxygen electrocatalysts (FeNi-NCS-2). The resultant FeNi-NCS-2 exhibits an impressive electrochemical performance, providing a reversible oxygen overpotential as low as 0.758 V. The ZAB with FeNi-NCS-2 as the air cathode shows a promising capacity of 639.71 mAh g?1 at 20 mA cm?2, a power density of 109.8 mW cm?2 and cycling stability of over 130 cycles at 10 mA cm?2 with an energy efficiency of about 55%, superior to the ZAB based on Pt/C–IrO2. The satisfactory electrocatalytic performance is mainly due to the Fe, Ni-based nanoparticles protected by graphitic carbon layers, hierarchical porous lamellar structures that promote the accessibility between the active centers and the electrolyte as well as self-growing tangled carbon nanotubes that provide fast transmission channels. This study presents a facile way for the synthesis of highly efficient ORR/OER bifunctional electrocatalysts for high-performance rechargeable ZABs. 相似文献