Ferrite impeder cores are used fo r concentration of magnetic flux in high frequency, RF, induction welding of steel tubes and pipes. In this application ferrite core experiences temperature upto 150 C and the core properties must be optimized for this environment. Properties which influences the efficiency and the speed of the process are :
• A high permeability (u) material to ensure high degree of magnetic flux concentration.
• A high Saturation flux density Bs, at the working temperature, which determines, the maximum field in which the ferrite core can usually perform.
• A high curie temperature at which the material ceased to concentrate magnetic flux, due to loss of ferrimagnetic properties.