The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature c...The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature chemical corrosion, low and high current level electrochemical corrosion, four types of porous structures, including uneven corrosion pits, hybrid porous, haystack type and bicontinuous model were prepared by chemically and electrochemically dealloying the porous Cu-34.6%Mn alloy made by the Gasar process. Then, the surface diffusion coefficient(DS) and the diffusion frequency(kD) of Cu atom, as well as the dissolution frequency(kE) of Mn atom were calculated with dealloying condition. The dealloyed morphologies for room temperature chemical corrosion and low current level electrochemical corrosion were similar due to the same DS. While the dealloyed structures changed from bulk hybrid porous structure to bicontinuous porous film with decreasing kD/kE.展开更多
Nucleation of gaseous hydrogen bubbles is the initial stage of GASAR process. Through the theoretical analysis, it has been identified that heterogeneous nucleation of bubbles as caps on the solid surfaces of impuriti...Nucleation of gaseous hydrogen bubbles is the initial stage of GASAR process. Through the theoretical analysis, it has been identified that heterogeneous nucleation of bubbles as caps on the solid surfaces of impurities is impossible and only the heterogeneous nucleation in pits and cracks in impurities is the most feasible way in the GASAR process. The results also show that the probability of bubble nucleation progressively decreases from Al, Cu and Ni to Fe molten metal, which is the result of the increasing adhesion work of liquid metal on alumina.展开更多
The effect of gas pressures on the mean pore size, the porosity and the pore size distribution of lotus-type porous magnesium fabricated with Gasar process were investigated. The theoretical analysis and the experimen...The effect of gas pressures on the mean pore size, the porosity and the pore size distribution of lotus-type porous magnesium fabricated with Gasar process were investigated. The theoretical analysis and the experimental results all indicate that there exists an optimal ratio of the partial pressures of hydrogen PH2 to argon PAr for producing lotus-type structures with narrower pore size distribution and smaller pore size. The effect of solidification mode on the pore size distribution and pore size was also discussed.展开更多
基金National Natural Science Foundation of China(51864026,51964030)Kunming University of Science and Technology Research Start-up Fund(KKSY201765025)Fund of Yunnan Provencal Education Department(2021J0048)。
基金Project(51371104)supported by the National Natural Science Foundation of China
文摘The evolution of nanoporous structure with dealloying condition was investigated, thus, the mechanism of porous structure evolution was uncovered. The Gasar Cu-Mn alloy was dealloyed by room and elevated temperature chemical corrosion, low and high current level electrochemical corrosion, four types of porous structures, including uneven corrosion pits, hybrid porous, haystack type and bicontinuous model were prepared by chemically and electrochemically dealloying the porous Cu-34.6%Mn alloy made by the Gasar process. Then, the surface diffusion coefficient(DS) and the diffusion frequency(kD) of Cu atom, as well as the dissolution frequency(kE) of Mn atom were calculated with dealloying condition. The dealloyed morphologies for room temperature chemical corrosion and low current level electrochemical corrosion were similar due to the same DS. While the dealloyed structures changed from bulk hybrid porous structure to bicontinuous porous film with decreasing kD/kE.
文摘Nucleation of gaseous hydrogen bubbles is the initial stage of GASAR process. Through the theoretical analysis, it has been identified that heterogeneous nucleation of bubbles as caps on the solid surfaces of impurities is impossible and only the heterogeneous nucleation in pits and cracks in impurities is the most feasible way in the GASAR process. The results also show that the probability of bubble nucleation progressively decreases from Al, Cu and Ni to Fe molten metal, which is the result of the increasing adhesion work of liquid metal on alumina.
基金This research was supported by the National Natural Science Foundation of China （No. 50404002）National Program on Key Basic Research Projects （No. 2004CCA05100）.
文摘The effect of gas pressures on the mean pore size, the porosity and the pore size distribution of lotus-type porous magnesium fabricated with Gasar process were investigated. The theoretical analysis and the experimental results all indicate that there exists an optimal ratio of the partial pressures of hydrogen PH2 to argon PAr for producing lotus-type structures with narrower pore size distribution and smaller pore size. The effect of solidification mode on the pore size distribution and pore size was also discussed.
