化学法制备Nd_2Fe_(14)B磁粉及其反应过程
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摘要
利用化学法制备Nd Fe B中间体,再通过两级还原退火成功制备了主相为Nd2Fe14B的Nd Fe B磁粉。采用X射线衍射(XRD)、透射电镜(TEM)及附带的X射线能谱仪(EDS)、差示扫描量热仪(DSC)和振动样品磁强计(VSM)等表征手段对样品的物相组成、微观组织结构、不同温度的相变和磁性能进行了分析,研究了Nd2Fe14B磁粉的形成过程。结果表明:采用化学法成功合成了分散良好的纳米尺寸的Nd Fe B中间体,中间体由球状Fe3O4颗粒和絮状物的Nd、B元素有机物配位体组成;中间体经过两级还原退火转变为Nd Fe B磁粉,通过800℃的一级还原退火使Nd Fe B中间体转化成NdFeO3、B_2O_3、Nd2O3和α-Fe相;二级还原退火在Ca H2辅助下的反应过程:首先B2O3在501℃下被还原成B相,接着678℃时,Nd2O3和Nd Fe O3被还原以形成α-Fe和Nd H2相,最后895℃时,B、Nd H2和α-Fe发生合金化反应形成Nd2Fe14B磁粉。
Nd Fe B intermediates were prepared by a chemical method and then Nd Fe B magnetic powder with a main phase of Nd2 Fe14 B was obtained by two-step reduction annealing. Phase, microstructure, phase transformation at different temperatures and magnetic properties of the samples were analyzed by XRD, TEM, DSC, VSM and so on. The formation mechanism of Nd2 Fe14 B magnetic powder was discussed. The results show that the nano-sized Nd Fe B intermediates with good dispersion, which are composed of spherical Fe_3O_4 particle and flocculent organic ligands of Nd and B elements, can be synthesized by the chemical method. In order to obtain Nd Fe B magnetic powder, the intermediate should be subjected to two-step reduction annealing. In the first-step reduction annealing process at 800 °C, the Nd Fe B intermediates are converted into Nd Fe O3, B2 O3, Nd2 O3 and α-Fe phases. The second-step annealing is performed with the aid of Ca H2, and the reaction process is as follows: firstly, B2 O3 is reduced into B phase at 501 °C, then Nd2O3 and Nd FeO3 are reduced into Nd H2 and α-Fe phases at 678 °C, and finally, B, Nd H2 and α-Fe are alloyed to form Nd2 Fe14 B magnetic powder at 895 °C.
Nd Fe B intermediates were prepared by a chemical method and then Nd Fe B magnetic powder with a main phase of Nd2 Fe14 B was obtained by two-step reduction annealing. Phase, microstructure, phase transformation at different temperatures and magnetic properties of the samples were analyzed by XRD, TEM, DSC, VSM and so on. The formation mechanism of Nd2 Fe14 B magnetic powder was discussed. The results show that the nano-sized Nd Fe B intermediates with good dispersion, which are composed of spherical Fe_3O_4 particle and flocculent organic ligands of Nd and B elements, can be synthesized by the chemical method. In order to obtain Nd Fe B magnetic powder, the intermediate should be subjected to two-step reduction annealing. In the first-step reduction annealing process at 800 °C, the Nd Fe B intermediates are converted into Nd Fe O3, B2 O3, Nd2 O3 and α-Fe phases. The second-step annealing is performed with the aid of Ca H2, and the reaction process is as follows: firstly, B2 O3 is reduced into B phase at 501 °C, then Nd2O3 and Nd FeO3 are reduced into Nd H2 and α-Fe phases at 678 °C, and finally, B, Nd H2 and α-Fe are alloyed to form Nd2 Fe14 B magnetic powder at 895 °C.
引文
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[4]Song Xiaoping(宋晓平),Wang Xiaotian(王笑天).Rare Metal Materials and Engineering(稀有金属材料与工程)[J],1994,23(3):1
[5]Yue Ming(岳明),Liu Xubo(刘旭波),Xiao Yaofu(肖耀福)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2003,32(7):490
[6]Huang Zhaohua(黄照华),Li Qiang(李强),Zhang Shiyan(张士岩)et al.Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2009,38(2):247
[7]Yu Lianqing(于濂清),Yan Mi(严密).Rare Metal Materials and Engineering(稀有金属材料与工程)[J],2008,37(9):1681
[8]Une Y,Sagawa M.Japan Inst Metals[J],2012,76(1):12
[9]Swaminathan V,Deheri P K,Bhame S D et al.Chemistry of Materials[J],2010,22(24):6509
[10]Deheri P K,Shukla S,Ramanujan R V.Journal of Solid State Chemistry[J],2012,186(2):224
[11]Bhame S D,Swaminathan V,Deheri P K et al.Advanced Science Letters[J],2010,3(2):174
[12]Rahimi H,Ghasemi A,Mozaffarinia R.Journal of Super conduct-ivity and Novel Magnetism[J],2016,29(8):2041
[13]Rahimi H,Ghasemi A,Mozaffarinia R et al.Journal of Magnetism and Magnetic Materials[J],2017,444(15):111
[14]Jadhav A P,Hussain A,Lee J H et al.New Journal of Chemistry[J],2012,36(11):2405
[15]Hussain A,Jadhav A P,Baek Y K et al.Journal of Nanoscience and Nanotechnology[J],2013,13(11):7717
[16]Ma H X,Kim C W,Kim D S et al.Nanoscale[J],2015,7(17):8016
[17]Haik Y,Chatterjee J,Chen C J.Journal of Nanoparticle Research[J],2005,7(6):675
[18]Zhang Q,Jiang Z,Yan B.Inorganic Chemistry Frontiers[J],2014,1(5):384
[19]Dong X L,Kim B K,Choi C J et al.Journal of Materials Research[J],2001,16(4):1083
[20]Boulanger J L,Autissier D.Journal de Physique IV[J],1993,03(C7):1305