| Recently high temperature permanent magnets whose using temperature must be higher than 400℃ are needed. 2:17 type SmCo permanent magnets are firstly chosen because of their high Curie temperature, low temperature coefficient, good anti-corrosive and good temperature stability. In order to study the effect factors of the components and heat-treatment process of high temperature 2:17 type SmCo permanent magnets on magnetic properties and microstructure, according to the component design principle of high temperature 2:17 type SmCo permanent magnets, the author studied heat-treatment process of Sm ( CobalFe0.1Cu0.16Zr0.04 )6.7 magnets and the relationship of components and magnetic properties. Lots of experiments and theoretic analysis have been carried out by use of modern analysis means including Scanning Electron Microscopy(SEM), Energy Dispersive Analysis(EDA), X-ray Diffra ction Analysis(XRD), Electron Probe Spectrum Analysis and Magnetic Force Microscopy Analysis(MFM), etc.The results of studying to Heat-treatment process of Sm(CobalFe0.1-Cu0.16Zr0.04)6.7 magnets show that the best magnetic properties of the magnet pre-sintered at 1190℃ for 40 minutes, sintered at 1200℃ for 1 hour, solid solution treated at 1185℃ for 2h, aged at 850℃ for 10h then quenched to 400℃ for 10h, have been obtained, Hci of 1931kA/m. Br and Ï increased with pre-sintering temperature increasing; Hci increased greatly with pre-sintering temperature increasing, especially at high temperature. Br and P changed slightly with sintering temperature changing when sintering temperature is low at 1190℃ to 1200℃. But when sintering temperature is higher than 1200℃,Br and Ï decreased greatly. Hci was very sensitive to sintering temperature; Hci decreased greatly when sintering temperature is lower or higher than 1200℃. The change of (BH)max with sintering temperature was the comprehensive results of the effect of Br and Hci. The magnetic properties of the studied magnet are better when the solid solution temperature is to 1185℃. The magnetic properties changed slightly at 850℃ aging for 3h or 10h.The effects of the components on microstructure and magnetic properties had been studied. The results show that There were more 1:5 phases and Br^ Hci and (BH)max was lower, but rectangle degree K was higher when magnets are of smaller z. So smaller z was benefit to high temperature magnetic 'properties. y\:5 would decrease, then Ay increase, then Hci increase with Cu content increasing. But non-magnetic phase would increase, then Br and (BH)max would decrease greatly when Cu content is too high and Sm content do not increase at the same time. The Sm ( CobaiFeo.iCuo.i6Zr0.o4 ) en magnet with low z and high Cu content had best magnetic properties at room and high temperature. Its microstructure was of fine, even non-hole and deposition along boundary depositing smoothly and evenly. Its MFM appearance picture was of cellular microstructure and bar and wave magnetic domain structure. The 2nd quadrant demagnetization curves was good at 400 °C yet, 3 of -0.15%/°C and Hci of 830kA/m, but began to worsen at 500 °C. |
