Highly active cathode catalysts for efficient formation/decomposition of Li_(2)O_(2)are essential for the performance improvement of lithium-oxygen batteries(LOBs).In this study,a grain-refining Co_(0.85)Se catalyst w...Highly active cathode catalysts for efficient formation/decomposition of Li_(2)O_(2)are essential for the performance improvement of lithium-oxygen batteries(LOBs).In this study,a grain-refining Co_(0.85)Se catalyst with a lattice spacing of 2.69 A of(101)plane closely matching with the(100)plane(2.72A)of Li_(2)O_(2)was applied for high-performance LOBs.Highly(101)plane exposed Co_(0.85)Se@CNT was synthesized by a simple one-pot hydrothermal method.The Co_(0.85)Se with the lattice matching effect not only led to the efficient conversion and polarized growth of Li_(2)O_(2),but also prevented the formation of byproducts.Density functional theory(DFT)calculations reveal that Co_(0.85)Se(101)plane has the intrinsic catalytic ability to generate/decompose Li_(2)O_(2)during ORR/OER process,due to its homogeneous electron distribution,suitable adsorption energy,and promoted Li_(2)O_(2)growth kinetics.As a consequence,the(101)plane highly exposed Co_(0.85)Se@CNT-80 electrode exhibited remarkable cycle stability over 2400 h at 100 mA/g and 290cycles at 500 mA/g,which is about 2 times longer than other electrodes.展开更多
The precipitation behavior of V-N microalloyed steel during normalizing process was studied by physicochemical phase analysis and transmission electron microscopy（TEM）. The effect of precipitation behavior on mechan...The precipitation behavior of V-N microalloyed steel during normalizing process was studied by physicochemical phase analysis and transmission electron microscopy（TEM）. The effect of precipitation behavior on mechanical properties was investigated by theoretical calculations. The results showed that 32.9% of V（C,N） precipitates remained undissolved in the austenite during the soaking step of the normalizing process. These precipitates prevented the growth of the austenite grains. During the subsequent cooling process, the dissolved V（C,N） re-precipitated and played a role in precipitation strengthening. The undissolved V（C,N） induced intragranular ferrite nucleation and refined the ferrite grains. Consequently, compared with hot-rolled steel, the normalized steel exhibited increased grain-refining strengthening but diminished precipitation strengthening, leading to an improvement of the impact energy at the expense of about 40 MPa yield strength.展开更多
The influence of Ti, B, RE (cerium-rich mixtures of rare earth) and Sr, applied in modification and refining processes, on A356 aluminum alloys has been studied with the aids of OM, etc. The results show that the grai...The influence of Ti, B, RE (cerium-rich mixtures of rare earth) and Sr, applied in modification and refining processes, on A356 aluminum alloys has been studied with the aids of OM, etc. The results show that the grain refining efficiency of Grain-Refining Aluminium Ingot (GRAI) and Al-Ti master alloys is similar. But the Tiaddition from GRAI has lower costs than that with Al-Ti master alloys. So A356 aluminum alloys produced with GRAI are feasible in economy. Grain refining with GRAI with 0.01%Ti plus additional 0.03% B offers significant advantages over that from GRAI with 0.1% Ti only in A356 aluminum alloys, which made the dendrite α(Al) grain structure transform into equiaxed α(Al) grain structure, plus a partially modified eutectic silicon structure. RE addition to A356 aluminum alloys with Sr modifier is enable to achieve small DAS, reduced pores, well-refined fibrous silicon, small and dispersive eutectic colonies.展开更多
The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the gr...The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.展开更多
基金supported by National Natural Science Foundation of China(Nos.52173286,52207249)Major basic research project of Natural Science Foundation of Shandong Province(No.ZR2023ZD12)+1 种基金the State Key Laboratory of Marine Resource Utilization in South China Sea(Hainan University)(No.MRUKF2023013)Open Program of Guangxi Key Laboratory of Information Materials(No.221024-K)。
文摘Highly active cathode catalysts for efficient formation/decomposition of Li_(2)O_(2)are essential for the performance improvement of lithium-oxygen batteries(LOBs).In this study,a grain-refining Co_(0.85)Se catalyst with a lattice spacing of 2.69 A of(101)plane closely matching with the(100)plane(2.72A)of Li_(2)O_(2)was applied for high-performance LOBs.Highly(101)plane exposed Co_(0.85)Se@CNT was synthesized by a simple one-pot hydrothermal method.The Co_(0.85)Se with the lattice matching effect not only led to the efficient conversion and polarized growth of Li_(2)O_(2),but also prevented the formation of byproducts.Density functional theory(DFT)calculations reveal that Co_(0.85)Se(101)plane has the intrinsic catalytic ability to generate/decompose Li_(2)O_(2)during ORR/OER process,due to its homogeneous electron distribution,suitable adsorption energy,and promoted Li_(2)O_(2)growth kinetics.As a consequence,the(101)plane highly exposed Co_(0.85)Se@CNT-80 electrode exhibited remarkable cycle stability over 2400 h at 100 mA/g and 290cycles at 500 mA/g,which is about 2 times longer than other electrodes.
基金Item Sponsored by National Science and Technology Pillar Program of China(2011BAE25B01)
文摘The precipitation behavior of V-N microalloyed steel during normalizing process was studied by physicochemical phase analysis and transmission electron microscopy（TEM）. The effect of precipitation behavior on mechanical properties was investigated by theoretical calculations. The results showed that 32.9% of V（C,N） precipitates remained undissolved in the austenite during the soaking step of the normalizing process. These precipitates prevented the growth of the austenite grains. During the subsequent cooling process, the dissolved V（C,N） re-precipitated and played a role in precipitation strengthening. The undissolved V（C,N） induced intragranular ferrite nucleation and refined the ferrite grains. Consequently, compared with hot-rolled steel, the normalized steel exhibited increased grain-refining strengthening but diminished precipitation strengthening, leading to an improvement of the impact energy at the expense of about 40 MPa yield strength.
文摘The influence of Ti, B, RE (cerium-rich mixtures of rare earth) and Sr, applied in modification and refining processes, on A356 aluminum alloys has been studied with the aids of OM, etc. The results show that the grain refining efficiency of Grain-Refining Aluminium Ingot (GRAI) and Al-Ti master alloys is similar. But the Tiaddition from GRAI has lower costs than that with Al-Ti master alloys. So A356 aluminum alloys produced with GRAI are feasible in economy. Grain refining with GRAI with 0.01%Ti plus additional 0.03% B offers significant advantages over that from GRAI with 0.1% Ti only in A356 aluminum alloys, which made the dendrite α(Al) grain structure transform into equiaxed α(Al) grain structure, plus a partially modified eutectic silicon structure. RE addition to A356 aluminum alloys with Sr modifier is enable to achieve small DAS, reduced pores, well-refined fibrous silicon, small and dispersive eutectic colonies.
基金financially supported by National High Technical Research and Development Program of China(No.G2002AA336080)National Natural Science Foundation of China(No.50374012)Natural Science Foundation of Jiangxi Province(No.0650047).
文摘The semi-solid slurry of A356 alloy, which is grain-refined by Al-Ti-B master alloy, is prepared by low superheat pouring and slight electromagnetic stirring. The effects of grain refining on the morphology and the grain size of the primary α phase in the slurry manufactured are researched. The results indicate that the slurry with particle-like and rosette-like primary α phases can be prepared by low superheat pouring and slight electromagnetic stirring from liquid A356 alloy grain-refined, in which the pouring temperature can be suitably raised. Compared with the A356 samples without grain refining, the grain size and particle morphology of primary α phase as well as the distribution of the grain with particle-like or rosette-like along radial in the ingot in A356 are markedly improved by grain refining.
