Magnetic properties and mechanical strength of MnZn ferrite

From MnZn ferrite ("6H20" of FDK production), cores having grain size of about 8/spl sim/10 /spl mu/m were produced by controlling the calcination temperature, after-calcination milling time, and sintering conditions. The ferrite powder production conditions and core microstructure were examined to determine their effects on the magnetic properties and mechanical strength of MnZn ferrite cores. A tendency of core loss to decline with a decrease in grain size was confirmed. Strength increased also with a decrease in grain size. Thus, a relation similar to that between strength and fracture toughness in the equation of Griffith-Irwin was noted. By these findings, it has become possible to produce MnZn ferrite cores with lower loss and greater strength.