The Manufacture of High Permeability Mn-Zn Ferrites by Atmospherical Protect

Abstract
For the manufacture of high permeability Mn-Zn ferrite cores, the zinc loss from the surface of sintering cores causes poor yield rate of final products. This experiment uses the atmospherical protection to reduce the evaporation of zinc. The control of the oxygen partial pressure and flow rate precisely can reduce the zinc loss about 20% to 35%, but it is not enough to get a good distribution of permeability of products, i.e. the distribution of initial permeability from 12000 to 15000 per products about 14% before atmospherical control and 25% after atmospherical control, respectively. Combination with precise control and zinc vapor compensation can increase the yield rate 9% to 15%. Another experiment to manufacture high permeability Mn-Zn ferrite cores for 15000±30% in a batch type furnace (about 13 Kg / batch), is to use a new engineering method to protect sintering core to avoid vaporizing zinc vapor, the yield rate can be rapidly increased from 25% to 75% and the effective capacity of furnace can be at least twofold. It is successful to manufacture homogeneous and high permeability of Mn-Zn ferrites both increasing the quality of products and decreasing the operating costs.