The influence of mean particle size on magnetic properties ofSm （ Co0.72Fe0. 15 Cu0. 1Zr0. 03 ） 7.5 sintered magnets, prepared by the conventional powder metallurgy method, was studied. With increasing ballmilling t...The influence of mean particle size on magnetic properties ofSm （ Co0.72Fe0. 15 Cu0. 1Zr0. 03 ） 7.5 sintered magnets, prepared by the conventional powder metallurgy method, was studied. With increasing ballmilling time, mean particle size decreases, specific surface increases, and sintering temperature decreases. The optimum sintering temperature of powders fabricated by baH-milling for 5, 7, 9 and 11 h are 1225, 1225, 1215 and 1215℃ respectively. The optimum value of Br, （BH）max, Hob and Hci of Sm （ Co0.72Fe0. 15 Cu0. 1Zr0. 03 ） 7.5 sintered magnets with powders ball-milling for 9 h and sintering at 1215 ℃ can reach 0.94 T, 708.4 kA·m^-1, 171.9 kJ·m^-3 and 2276.6 kA·m^-1 respectively, and the irreversible flux loss is less than 5 % after the sample ageing at 550 ℃ for 2 h, so the temperature stability improves and the magnets may be expected to be applied in the circumstances of 550 ℃.展开更多
Rare earth permanent magnets Sm（Co, Fe, Cu, Zr）z with outstanding performance and high-temperature thermal stability were fabricated. Optimized by Fe content and process, Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5 magnet with...Rare earth permanent magnets Sm（Co, Fe, Cu, Zr）z with outstanding performance and high-temperature thermal stability were fabricated. Optimized by Fe content and process, Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5 magnet with B1〉0.75 T and Hci〉1300 kA/m at 300 ℃ can be obtained. According to the performance data of Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5, the magnetic field along central axis Bz in periodic permanent magnet （PPM） focusing system was simulated using electromagnetic field analysis software Maxwell 2D/3D. The Bz exhibited typical cosine curve along central axis, and the peak value of Bz was high enough to meet the demand of PPM focusing system at room temperature even at 200±20 ℃. Additionally, a kind of simple cooling structure for PPM focusing system was designed by setting cooling pipe between polepieces. Simulated results showed that smooth cosine curve of Bz was successfully achieved with good control of the thickness of cooling pipe.展开更多
Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS...Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS. The results indicate that the antioxidation effect of the alloy powder treated in silane solution is better than that of the other methods. The alloy powders treated in stearic acid （SA） solution and polymethyl methacrylate （PMMA） solution can prevent powders from oxidation for a short period of time. Silane solution is not suitable for metal injection molding （MIM） because it severely damages the magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets. SA solution can not only prevent powders from oxidizing in MIM, but also does not damage magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z magnets. The oxygen content of Sm（Co, Cu, Fe, Zr）z-sintered magnets by MIM is 3300μg·g^-1.展开更多
Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated...Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated. As a result, the density of the magnet is obviously improved with the increase of sintering pressure, but the coercivity drops since Sm2Fe17Nx has decomposed into SmN, α-Fe and N2. When sintering temperature was only above 200 ℃ under 1 GPa sintering pressure, the coercivity even begins to decrease, which indicates that high pressure promotes the decomposition of the Sm2Fe17Nx at lower temperature. The decomposition is also proved by the decrease of nitrogen and increase of α-Fe in the magnets.展开更多
High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decompo...High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decomposition dynamic of the magnets were investigated.It is found that higher sintering temperature improves the densification of the magnets, while deteriorates their magnetic properties simultaneously due to the decomposition of the Sm2Fe17Nx.Sintering at lower temperature can preserve the crystal structure of Sm2Fe17Nx compound, while the powders cannot be consolidated into a fully dense compact.An increased compressive pressure leads to better magnetic properties and higher density for the magnet at the same sintering temperature.展开更多
文摘The influence of mean particle size on magnetic properties ofSm （ Co0.72Fe0. 15 Cu0. 1Zr0. 03 ） 7.5 sintered magnets, prepared by the conventional powder metallurgy method, was studied. With increasing ballmilling time, mean particle size decreases, specific surface increases, and sintering temperature decreases. The optimum sintering temperature of powders fabricated by baH-milling for 5, 7, 9 and 11 h are 1225, 1225, 1215 and 1215℃ respectively. The optimum value of Br, （BH）max, Hob and Hci of Sm （ Co0.72Fe0. 15 Cu0. 1Zr0. 03 ） 7.5 sintered magnets with powders ball-milling for 9 h and sintering at 1215 ℃ can reach 0.94 T, 708.4 kA·m^-1, 171.9 kJ·m^-3 and 2276.6 kA·m^-1 respectively, and the irreversible flux loss is less than 5 % after the sample ageing at 550 ℃ for 2 h, so the temperature stability improves and the magnets may be expected to be applied in the circumstances of 550 ℃.
基金the National Basic Research Program (973) (2007CB31407)the International S&T Cooperation Program of China (2006DFA53410)
文摘Rare earth permanent magnets Sm（Co, Fe, Cu, Zr）z with outstanding performance and high-temperature thermal stability were fabricated. Optimized by Fe content and process, Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5 magnet with B1〉0.75 T and Hci〉1300 kA/m at 300 ℃ can be obtained. According to the performance data of Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5, the magnetic field along central axis Bz in periodic permanent magnet （PPM） focusing system was simulated using electromagnetic field analysis software Maxwell 2D/3D. The Bz exhibited typical cosine curve along central axis, and the peak value of Bz was high enough to meet the demand of PPM focusing system at room temperature even at 200±20 ℃. Additionally, a kind of simple cooling structure for PPM focusing system was designed by setting cooling pipe between polepieces. Simulated results showed that smooth cosine curve of Bz was successfully achieved with good control of the thickness of cooling pipe.
基金Project supported by Specialized Research Fundfor the Doctoral Programof Higher Education (20040008015)ProgramforNew Century Excellent Talents in University (NCET)
文摘Antioxidation effects on Sm （Co, Cu, Fe, Zr）z-sintered magnets treated by different methods were studied through TGA and DTA. Microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets was analyzed through SEM and EDS. The results indicate that the antioxidation effect of the alloy powder treated in silane solution is better than that of the other methods. The alloy powders treated in stearic acid （SA） solution and polymethyl methacrylate （PMMA） solution can prevent powders from oxidation for a short period of time. Silane solution is not suitable for metal injection molding （MIM） because it severely damages the magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z-sintered magnets. SA solution can not only prevent powders from oxidizing in MIM, but also does not damage magnetic properties and microstructure of Sm（Co, Cu, Fe, Zr）z magnets. The oxygen content of Sm（Co, Cu, Fe, Zr）z-sintered magnets by MIM is 3300μg·g^-1.
文摘Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated. As a result, the density of the magnet is obviously improved with the increase of sintering pressure, but the coercivity drops since Sm2Fe17Nx has decomposed into SmN, α-Fe and N2. When sintering temperature was only above 200 ℃ under 1 GPa sintering pressure, the coercivity even begins to decrease, which indicates that high pressure promotes the decomposition of the Sm2Fe17Nx at lower temperature. The decomposition is also proved by the decrease of nitrogen and increase of α-Fe in the magnets.
文摘High performance Sm2Fe17Nx magnetic powders were fabricated by ball-milling method and were compacted using spark plasma sintering(SPS) technique.Effects of processing conditions on the magnetic properties and decomposition dynamic of the magnets were investigated.It is found that higher sintering temperature improves the densification of the magnets, while deteriorates their magnetic properties simultaneously due to the decomposition of the Sm2Fe17Nx.Sintering at lower temperature can preserve the crystal structure of Sm2Fe17Nx compound, while the powders cannot be consolidated into a fully dense compact.An increased compressive pressure leads to better magnetic properties and higher density for the magnet at the same sintering temperature.
