China Nonferrous Metallurgy

In response to the issue of value-added resource utilization of steel slag, this paper took low-iron electric furnace steel slag, high-density soil, and talc as raw materials, and Fe₂O₃ as additive, and prepared SiO₂-CaO-MgO(15%)-Al₂O₃ system ceramics under air atmosphere and N₂ atmosphere. It was focused on the iron distribution state and magnetic performance in this system, and examined the feasibility of using steel slag to prepare functional ceramics with soft magnetic characteristics, in order to avoid adding hard magnetic, Y-type ferrite, NiZnCu ferrite and other materials in the preparation process of soft magnetic ceramic materials, and to reduce the cost. The experimental results showed that using electric furnace steel slag, it was possible to prepare soft magnetic ceramics with a saturated magnetization intensity of 6.38 emu/g under the sintering conditions of N₂ atmosphere and 1150℃. There were three iron distribution states in the pyroxene system ceramics, the pyroxene phase with solid solution Fe²⁺, the magnetite and the hematite phase. The change process of iron element in the air sintering process was that the hematite had undergone decomposition reaction before 1150℃, and the part of magnetite generated in the range of 1150-1200℃ melted with the generated pyroxene, which promoted densification of the ceramics, and the decomposition reaction ended at 1200℃, and the hematite was converted into the magnetite phase with magnetic. Some of the test samples showed hematite after sintering, which was due to the oxidation of magnetite generated at high temperature during the cooling of the test sample in air atmosphere. The magnetic properties of the samples sintered in N₂ atmosphere were significantly better than those sintered in air atmosphere, and the magnetic properties were positively correlated with the content of theite phase in the samples. The magnetic properties parameters of the test sample sintered at 1150℃ in N₂ atmosphere optimal, with Ms and Mr of 6.38emu/g and 1.38emu/g, respectively. There was a certain gap between the Ms value of the samples prepared in this study and of the plasma sintered MnZn ferrite laminated composite ceramics (33.05emu/g), but the results could provide reference for subsequent preparation of soft magnetic ceramic materials from steel slag.