変成ガスふんい気中でのMn-Znフェライトの焼成

Abstract

Since Mn-Zn ferrite is to be oxydized in air atmosphere at a temperature range between 500°C and 1100°C, αFe2O3 and Mn2O3 are easily precipitated in the manufacturing process and magnetic properties of Mn-Zn ferrite are usually detoriorated. In order to remedy such a fault in the manufacturing process of Mn-Zn ferrite, rapid cooling method in air or slow cooling method in N2 is used. In former case, however, many cracks may occur in ferrite body and even in latter case the technical problems about oxygen partial pressure are remained. In this report, the authors tried to fire Mn-Zn ferrite in N2+CO2 gas atmosphere converted from air and town gas or commercial propane gas. The magnetic properties of Mn-Zn ferrites fired in converted gas atmosphere are shown in the relations among Bm (maximum flux density in core subject to alternating magnetizing force), Hm (maximum magnetizing force in core subject to alternating magnetizing force), μAC (amplitude permeability) and W (hysteresis loss). The results show that the magnetic properties of Mn-Zn ferrite fired in the converted gas atmosphere are equal to the magnetic properties of Mn-Zn ferrite fired in N2+0.5%O2 atmosphere which is most suitable for the firing of Mn-Zn ferrite. So that, even if CO2 gas in converted gas had the effect of oxidizing ferrite body, the effect might be only exerted on the oxidation of metal ions in spinel ferrite because the effect is not so strong. This has a good advantage in making Mn-Zn ferrite in commercial production which is connected with financial and O2 partial pressure problems.