M型稀土永磁铁氧体的微观结构与磁性研究

采用粉末冶金工艺,结合CaSiO_3与BBSS助熔剂的复合掺杂技术,制备了M型稀土永磁铁氧体。用费氏粒度仪测量成形用颗粒料的平均粒度,用SEM、EDS、XRD、永磁铁氧体测量仪等分析测试样品的显微结构、物相、断面形貌及磁学性能,用浮力法测定样品表观密度。结果表明:CaSiO_3与BBSS助熔剂的复合掺杂促进了M型稀土永磁铁氧体晶粒的均匀生长,改善了产品的取向度,从而明显改善了产品的磁性能及内禀矫顽力HCJ的温度系数β(HCJ),但铁氧体的居里温度略为下降。对Ca_(0.45)La_(0.45)Sr_(0.1)Fe_(10.3)Co_(0.3)O_(19-δ)预烧料,细粉碎时添加0.7%的CaSiO_3、0.4%的助熔剂BBSS(均为质量分数),经成形、烧结之后,可获得Br为455 m T,HCJ为412 k A/m,M*值为6 275.3、Hk/HCJ为95.8%的M型高性能稀土永磁铁氧体。

Microstructure and magnetic properties of M-type rare-earth permanent ferrites

The powder metallurgy method was initially used to prepare M-type rare-earth permanent ferrites with the composite addition of CaSiO3 and BBSS flux. Then the average particle size of the forming materials were test-ed by Fisher particle size analyzers,meanwhile,the microstructure,phases,fracture surfaces and magnetic prop-erties of the samples were also measured by SEM,EDS,XRD and permanent magnetic ferrite meters,etc. Final-ly,the apparent density was tested by buoyancy method. Experimental results show that,the composite addition of CaSiO3 and BBSS flux promotes the uniform growth of M-type ferrite grains,and ameliorates the orientations, thereby significantly improves the magnetic properties and the temperature coefficient of HCJ. But the Curie tem-perature of ferrite decreases slightly. When 0.7%(mass percent) CaSiO3 and 0.4%(mass percent) BSSS flux are added into the sintered materials (Ca0.45La0.45Sr0.1Fe10.3Co0.3O19-δ) at the time of the fine pulverization,M-type high performance rare-earth permanent ferrite are obtained with Br of 455 mT,HCJ of 412 kA/m,M*of 6 275.3 and Hk/HCJ of 95.8%.