Manganese-Zinc-Ferrites with Improved Magnetic and Mechanical Properties

The 3-component system of manganese-zinc-ferrites is being thoroughly investigated as regards its intrinsic properties. The macroscopic properties of these spinel are variable within broad limits over the process of microstructure formation. Oxides of the 3d and 4d elements are frequently used as additives to determine the temperature dependence of the initial permeability and the electrical conductivity of manganese-zinc-ferrites. Additives for acceleration of sintering based on oxides of the elements of the third, fourth and fifth main group of the periodic system require an improved knowledge about the process of microstructure formation of 8 - 10 components systems especially as regards grain growth, microchemistry and the structure of the grain boundary. Due to the increased application of silicon power semiconductors (IGBT, power MOSFET) high demands are made as well on the mechanical properties of ferrite components, especially on tensile strengths, crack toughness and thermal shock resistivity. Proceedings from the basics of linearly elastic fracture mechanics experimental results are presented as regards increase of tensile strength, reduction of the mechanical stress dependence of the initial permeability and improvement of the thermal shock resistivity of manganese-zinc-ferrites for commercial applications. An interpretation of the microstructure-properties ratio is carried out by means of microstructural and microchemical investigations using the high-resolving transmission electron microscopy