Isotropic Sm-Fe-N bonded magnets were obtained by additive manufacturing(AM). The technique used was the so-called powder bed fusion(PBF) and the feedstock was composed of a polymeric binder(PA-12) and Sm-Fe-N flake p...Isotropic Sm-Fe-N bonded magnets were obtained by additive manufacturing(AM). The technique used was the so-called powder bed fusion(PBF) and the feedstock was composed of a polymeric binder(PA-12) and Sm-Fe-N flake particles(Nitroquench-P). The AM set-up equipment uses a computer-controlled CO2 laser beam to melt the binder and constructs magnets layer-by-layer. In order to develop this study, a cylinder with 10 mm of both height and diameter was selected as the shape of samples. Specimens were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Magnetic properties were measured in a hysteresis graph. XRD results indicate that there is no degradation of the main magnetic phase(SmFe7 Nx). In the AM component, porous regions were identified on SEM micrographs, as well as magnetic particles and polymeric binder. Remanence values(Br) as great as 0.3 T are achieved, while intrinsic coercivities remain in the range from 616 up to 642 kA/m. An additional isostatic compression of the parts results in greater remanence, which is directly proportional to the density increase. Coercivity is also sensitive to the porosity decrease, probably due to a better interlocking of particles. Current results indicate AM as a promising route for near net-shape manufacturing of Sm-Fe-N permanent magnets, a market niche yet to be widely explored.展开更多
Using pure Sm and Fe powders as starting materials,high coercive Sm-Fe-N mag- nets have been prepared by mechanical alloying in combination with beat treatment and nitriding.The best result is:_iH_c=33.1 kA/cm(41.6 kO...Using pure Sm and Fe powders as starting materials,high coercive Sm-Fe-N mag- nets have been prepared by mechanical alloying in combination with beat treatment and nitriding.The best result is:_iH_c=33.1 kA/cm(41.6 kOe)and(BH)_(max)=98.7 kJ/cm^3(12.4 MGOe).The phases formed in the specimens during mechanical alloying, crystallizing and nitriding processes were examined by X-ray diffraction technique.The magnetic properties of the specimens were measured with the pulsed magnetometer in field up to 12 T.Experimental results show that mechanical alloying is an efficient ap- proach for preparing high coercive magnets.As an important factor for obtaining a high coercivity,the grain sizes of magnets are about tens of nanometer.The presence of some soft magnetic phases in the specimens leads to a neck on the demagnetization curve.展开更多
钐铁氮化合物(Sm_(2)Fe_(17)N_(3))因具有比钕铁硼(Nd_(2)Fe_(14)B)更高的磁晶各向异性场和居里温度值及更少的稀土含量,成为新型稀土永磁材料研究热点。但是,由于钐铁氮在600℃左右会分解导致永磁性能消失,因此常规的高温烧结工艺并不...钐铁氮化合物(Sm_(2)Fe_(17)N_(3))因具有比钕铁硼(Nd_(2)Fe_(14)B)更高的磁晶各向异性场和居里温度值及更少的稀土含量,成为新型稀土永磁材料研究热点。但是,由于钐铁氮在600℃左右会分解导致永磁性能消失,因此常规的高温烧结工艺并不适用于钐铁氮烧结磁体的制备,现只能将其与高分子材料复合用作塑磁材料,这就导致Sm_(2)Fe_(17)N_(3)的磁学性能无法得到充分发挥。因此,开发低温成型工艺制备全金属高密度块状磁体是获取高性能钐铁氮磁体的关键。经过30多年的努力,科研人员已开发出多种制备钐铁氮磁体的低温快速成型工艺,并获得最大磁能积达到199 k J/m^(3)的高性能磁体。本研究将从磁体的制备方法出发,总结当前块状钐铁氮磁体的研究现状及面临的问题,尤其针对不同成型方法出现矫顽力下降的现象提出分析,并对其今后的发展做出展望。展开更多
文摘Isotropic Sm-Fe-N bonded magnets were obtained by additive manufacturing(AM). The technique used was the so-called powder bed fusion(PBF) and the feedstock was composed of a polymeric binder(PA-12) and Sm-Fe-N flake particles(Nitroquench-P). The AM set-up equipment uses a computer-controlled CO2 laser beam to melt the binder and constructs magnets layer-by-layer. In order to develop this study, a cylinder with 10 mm of both height and diameter was selected as the shape of samples. Specimens were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Magnetic properties were measured in a hysteresis graph. XRD results indicate that there is no degradation of the main magnetic phase(SmFe7 Nx). In the AM component, porous regions were identified on SEM micrographs, as well as magnetic particles and polymeric binder. Remanence values(Br) as great as 0.3 T are achieved, while intrinsic coercivities remain in the range from 616 up to 642 kA/m. An additional isostatic compression of the parts results in greater remanence, which is directly proportional to the density increase. Coercivity is also sensitive to the porosity decrease, probably due to a better interlocking of particles. Current results indicate AM as a promising route for near net-shape manufacturing of Sm-Fe-N permanent magnets, a market niche yet to be widely explored.
文摘Using pure Sm and Fe powders as starting materials,high coercive Sm-Fe-N mag- nets have been prepared by mechanical alloying in combination with beat treatment and nitriding.The best result is:_iH_c=33.1 kA/cm(41.6 kOe)and(BH)_(max)=98.7 kJ/cm^3(12.4 MGOe).The phases formed in the specimens during mechanical alloying, crystallizing and nitriding processes were examined by X-ray diffraction technique.The magnetic properties of the specimens were measured with the pulsed magnetometer in field up to 12 T.Experimental results show that mechanical alloying is an efficient ap- proach for preparing high coercive magnets.As an important factor for obtaining a high coercivity,the grain sizes of magnets are about tens of nanometer.The presence of some soft magnetic phases in the specimens leads to a neck on the demagnetization curve.
文摘钐铁氮化合物(Sm_(2)Fe_(17)N_(3))因具有比钕铁硼(Nd_(2)Fe_(14)B)更高的磁晶各向异性场和居里温度值及更少的稀土含量,成为新型稀土永磁材料研究热点。但是,由于钐铁氮在600℃左右会分解导致永磁性能消失,因此常规的高温烧结工艺并不适用于钐铁氮烧结磁体的制备,现只能将其与高分子材料复合用作塑磁材料,这就导致Sm_(2)Fe_(17)N_(3)的磁学性能无法得到充分发挥。因此,开发低温成型工艺制备全金属高密度块状磁体是获取高性能钐铁氮磁体的关键。经过30多年的努力,科研人员已开发出多种制备钐铁氮磁体的低温快速成型工艺,并获得最大磁能积达到199 k J/m^(3)的高性能磁体。本研究将从磁体的制备方法出发,总结当前块状钐铁氮磁体的研究现状及面临的问题,尤其针对不同成型方法出现矫顽力下降的现象提出分析,并对其今后的发展做出展望。
