Development of Optimum Preparation Conditions of Fe-Deficient M-Type Ca-Sr-La System Hexagonal Ferrite Magnet

• Published in: IEEE transactions on magnetics Vol. 57; no. 2; pp. 1 - 7
• Main Authors: Huang, Ching-Chien, Lin, Shih-Hao, Mo, Chin-Chieh, Hsiao, Tsung-Han, Tai, Yen-Hua, Hung, Yung-Hsiung, Chiu, Chun-Hao, Hsu, H.-H., Cheng, C.-H.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-02-2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Additives; By-product; Calcination; circular economy; Cobalt; Cobalt oxides; Composition; Ferrites; hard ferrite; Iron; iron oxide powder; Iron oxides; Low temperature; magnet; Magnetic properties; Magnetism; motor; Permanent magnets; Physical properties; Powders; Roasting; Saturation magnetization; Silicon dioxide; Sintering (powder metallurgy); Stoichiometry; Strontium
• ISSN: 0018-9464; 1941-0069
• DOI: 10.1109/TMAG.2020.3042095

In this work, an experiment was carried out to investigate the preparation condition of anisotropic Fe-deficient M-type Ca-Sr-La system ferrite with optimum magnetic and physical properties using the raw material Fe 2 O 3 from steel industrial iron oxide waste. The compositions of the calcined ferrites were chosen according to the stoichiometry <inline-formula> <tex-math notation="LaTeX">{\mathrm {Ca}}_{1-x-y} </tex-math></inline-formula>La x Sr y Fe 10.9 Co z O 19 , where M-type single-phase calcined powder was synthesized with a composition of <inline-formula> <tex-math notation="LaTeX">x = 0.45 </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">y = 0.18 </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">z= 0 </tex-math></inline-formula>. The effect of CaO, SiO 2 , and Co 3 O 4 inter-additives on the Ca-Sr-La system ferrite was also discussed in order to obtain low-temperature sintered magnets. The magnetic properties of <inline-formula> <tex-math notation="LaTeX">B_{r} = 4570 </tex-math></inline-formula> Gauss, <inline-formula> <tex-math notation="LaTeX">_{b}H_{c} = 4320 </tex-math></inline-formula> Oe, <inline-formula> <tex-math notation="LaTeX">_{i}H_{c} = 5260 </tex-math></inline-formula> Oe, and (<inline-formula> <tex-math notation="LaTeX">BH </tex-math></inline-formula>)<inline-formula> <tex-math notation="LaTeX">_{\mathrm {max}}= 5.16 </tex-math></inline-formula> MGOe were obtained for Ca-Sr-La system hard magnets with low cobalt content at 1.85 wt%. The magnetic properties of the prepared magnets really good compared to that of the traditional Sr-La-cobalt (Co) M-type ferrite, which has been the highest grade M-type hard ferrite. The remarkable steel industrial iron oxide waste Fe 2 O 3 is recycled to produce high-end permanent magnets under an output power of < 1 kW, which will eventually be used in high-efficiency motors.