A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching...A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching time on chemical composition,particle size and magnetic properties was investigated.Due to the low reduction potential of rare earth element(REE),the Nd-rich phase was preferentially leached.The use of an acid concentration of 0.5 mol/L,a solid to liquid ratio of 1/10 and a leaching time of 30 min was sufficient to leach the Nd-rich phase.Atomic resolution transmission electron microscopy was employed to examine the surface structure and chemistry of the leached Nd_(2)Fe_(14)B powder.It is revealed that the leaching process affects not only the Nd-rich phase but also the matrix grains,resulting in the formation of a predominant oxygen-rich amorphous reaction layer,25 nm thick.However,the oxygen content is reduced from 3500 to 2500 ppm and the magnetic saturation is increased by 8%.This method is a promising addition to the HPMS process,as the powder can be mixed with fresh,unoxidized grain boundary phase to produce recycled magnets with high remanence.展开更多
Texture evolution in nanocomposite Nd_2Fe_ 14B/α-Fe magnets prepared by direct melt spinning was investigated. The free surface and wheel-contacted surface exhibit different texture direction. Modification of composi...Texture evolution in nanocomposite Nd_2Fe_ 14B/α-Fe magnets prepared by direct melt spinning was investigated. The free surface and wheel-contacted surface exhibit different texture direction. Modification of composition not only enhances magnetic properties, but also changes texture direction of the ribbon. Low temperature heat treatment can increase the magnetic properties to some extent, and high temperature annealing decreases the magnetic properties. Both low and high temperature heat treatment have effects on grain orientation, but the difference still exists between the two surfaces of the ribbon. So it is infeasibility to prepare anisotropic Nd_2Fe_ 14B/α-Fe nanocomposite magnets by direct melt spinning.展开更多
基金Project supported by the German Federal Ministry of Education and Research as part of the program"FH-Kooperativ"the European Commission under the Horizon Europe Research and Innovation Program(101058598)。
文摘A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching time on chemical composition,particle size and magnetic properties was investigated.Due to the low reduction potential of rare earth element(REE),the Nd-rich phase was preferentially leached.The use of an acid concentration of 0.5 mol/L,a solid to liquid ratio of 1/10 and a leaching time of 30 min was sufficient to leach the Nd-rich phase.Atomic resolution transmission electron microscopy was employed to examine the surface structure and chemistry of the leached Nd_(2)Fe_(14)B powder.It is revealed that the leaching process affects not only the Nd-rich phase but also the matrix grains,resulting in the formation of a predominant oxygen-rich amorphous reaction layer,25 nm thick.However,the oxygen content is reduced from 3500 to 2500 ppm and the magnetic saturation is increased by 8%.This method is a promising addition to the HPMS process,as the powder can be mixed with fresh,unoxidized grain boundary phase to produce recycled magnets with high remanence.
文摘Texture evolution in nanocomposite Nd_2Fe_ 14B/α-Fe magnets prepared by direct melt spinning was investigated. The free surface and wheel-contacted surface exhibit different texture direction. Modification of composition not only enhances magnetic properties, but also changes texture direction of the ribbon. Low temperature heat treatment can increase the magnetic properties to some extent, and high temperature annealing decreases the magnetic properties. Both low and high temperature heat treatment have effects on grain orientation, but the difference still exists between the two surfaces of the ribbon. So it is infeasibility to prepare anisotropic Nd_2Fe_ 14B/α-Fe nanocomposite magnets by direct melt spinning.
