Relationship between Residual Loss and Microstructure of Mn-Zn Ferrites

The core loss characteristics of the Mn-Zn ferrite cores with various grain sizes, electric conductivities and cross sectional areas are analyzed. Apart of the residual loss depends on the grain size. It is 4 orders of magnitude larger than the intragrain eddy current loss estimated classically. On the other hand, the cote loss calculated by using the dynamic magnetic loss parameter recently introduced by Saotome and Sakaki includes the part. This indicates that the part of the residual loss is related to the interaction between the applied field and the induced magnetic flux

Atmosphere Controlled Roller Hearth Kiln for High Performance Mn-Zn Ferrites

A new roller hearth kiln(RHK) has been developed, which satisfies not only the highest quality of Mn-Zn ferrites, but also large quantity of production. Using the RHK (the length is 50m), the total sintering time is reduced to less than 11 hours, that is shorter than the half of the case of pusher kiln. Then the productive capacity of the RHK achieved 100 ton per month. Moreover, the control of oxygen content during sintering and the subsequently cooling is performed precisely, so that two different types of Mn-Zn ferrite, i.e. high-permeability and low power loss materials, can be sintered simultaneously in the RHK. The electromagnetic properties of these materials reach to the highest level in mass production. This paper describes the basic structure and the characteristics of the new RHK, and shows the magnetic properties of Mn-Zn ferrites which are sintered by the RHK