| Title |
Preparation of Quasi-nano-sized of Ba-Zn Ferrites Powders by Self-Propagating High Temperature Synthesis and Mechanical Milling |
| Authors |
최경숙(Choi, Kyung-Suk) ; 이종재(Lee, Jong-Jae) ; 김혁돈(Kim, Hyuk-Don) ; 최용(Choi, Yong) ; 이상헌(Lee, Sang-Heon) |
| Keywords |
SHS ; Mechanical milling ; Quasi-nano ; Ferrite powder |
| Abstract |
Ba-Zn ferrite powders for electromagnetic insulator were synthesized by self-propagating high-temperature synthesis(SHS) with a reaction of xBaO_2+(1-x)ZnO+0.5Fe_2O_3+Fe{ rightarrow}Ba_xZn_{1-x}Fe_2O_4. In this study, phase indentification of SHS products was carried out by using x-ray diffractometry and quasi-nano sized Ba-Zn powders were prepared by a pulverizing process. SHS mechanism was studied by thermodynamical analysis about oxidation reaction among BaO_2, ZnO, Fe_2O_3, and Fe. As oxygen pressure increases from 0.25 MPa to 1.0 MPa, the SHS reactions occur well and make clearly the SHS products. X-ray analysis shows that final SHS products formed with the ratio of BaO_2/ZnO of 0.25, 1.0 and 4.0, are mainly Ba_xZn_{1-x}Fe_2O_4. Based on thermodynamical evaluation, the heat of formation increases in the order of ZnFe_2O_4, BaFe_2O_4, and Ba_xZn_{1-x}Fe_2O_4. This supports that Ba_xZn_{1-x}Fe_2O_4 phase is predominately formed during SHS reaction. The SHS reactions to form Ba_xZn_{1-x}Fe_2O_4 depends on oxygen partial pressure, and the heat of formation during the SHS reaction. The SHS reactions tends to occur well with increasing the oxygen partial pressure and BaO2/ZnO ratio in the reactants This means that the SHS reaction for the formation of Ba-Zn ferrite includes the reduction of BaO2/ZnO and the oxidation of Fe. Ba_xZn_{1-x}Fe_2O_4 powders after pulverizing is agglomeratedwith a size of about 50μm, in which quasi-nano sized particles with about 300nm are present. |