The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder f...The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1 wt.% and 3 wt.%. The addition was done during casting of the metal in the mold at the last cooling step of the melt cast iron. These additions have a significant impact on the phenomenon of solidifi cation as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat. The cooling rate directly affects the microstructure and electrochemical behavior. This is confirmed by SEM observations and electrochemical tests. Furthermore, the addition of niobium transforms the microstructure of gray cast iron from cellular structure into totally dendritic structure. As a consequence, the niobium addition affected the shape and size of graphite, thus considerably reducing the corrosion current density by increasing the polarization resistance Rp.展开更多
This work describes the scandium doping effect on the structural and magnetic properties of delafossite-type oxides CuCr1?- xScxO2. The lattice parameters were found to vary according to Vegard’s low. A reflection br...This work describes the scandium doping effect on the structural and magnetic properties of delafossite-type oxides CuCr1?- xScxO2. The lattice parameters were found to vary according to Vegard’s low. A reflection broadening is observed, that is ascribed to local lattice distortion due to the ionic radius difference between Cr3+ and the non-magnetic dopants. Magnetic susceptibility measurements show that the dominant interactions are antiferromagnetic (AFM) but that doping induces significant changes. The coupling between the local spins at the Cr sites and doped metal transition may enhance spin fluctuations at the Cr sites, which break the residual magnetic degeneracy as fluctuation-induced symmetry breaking in a highly magnetic degenerate ground state manifold of some frustrated systems.展开更多
文摘The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1 wt.% and 3 wt.%. The addition was done during casting of the metal in the mold at the last cooling step of the melt cast iron. These additions have a significant impact on the phenomenon of solidifi cation as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat. The cooling rate directly affects the microstructure and electrochemical behavior. This is confirmed by SEM observations and electrochemical tests. Furthermore, the addition of niobium transforms the microstructure of gray cast iron from cellular structure into totally dendritic structure. As a consequence, the niobium addition affected the shape and size of graphite, thus considerably reducing the corrosion current density by increasing the polarization resistance Rp.
文摘This work describes the scandium doping effect on the structural and magnetic properties of delafossite-type oxides CuCr1?- xScxO2. The lattice parameters were found to vary according to Vegard’s low. A reflection broadening is observed, that is ascribed to local lattice distortion due to the ionic radius difference between Cr3+ and the non-magnetic dopants. Magnetic susceptibility measurements show that the dominant interactions are antiferromagnetic (AFM) but that doping induces significant changes. The coupling between the local spins at the Cr sites and doped metal transition may enhance spin fluctuations at the Cr sites, which break the residual magnetic degeneracy as fluctuation-induced symmetry breaking in a highly magnetic degenerate ground state manifold of some frustrated systems.
基金National High Technology Research and Development Program of China(2006AA03Z202,2006AA03Z204)Supported by the French Embassy in Beijing,the International Laboratory for the Applications of Superconductor and Magnetic Materials(LAS2M-CNRS-NIN)
