IBS Magnet - Magnetic and Physical Properties of Magnet Materials

What Does it Mean?

The energy product (B x H) max. indicates the magnetic quality. The higher the product, the more "energy" is stored in a magnet material. It results from the largest B and H to be drawn inside the demagnetisation curve.

The remanence Br is measured in Tesla (T) or Millitesla (mT). In the CGS system, the term is Gauss (G). The remanence is the magnetisation or flux density remaining in a magnet material after saturation, measured in a closed magnetic circuit.

The coercivity Hc is the negative field strength in kA/m or Oersteds (Oe) which is necessary to bring the remanence to zero again. The higher the value, the better the ability of a magnet to withstand negative or alternating fields. A distinction is made between _BH_C and _JH_C. The coercivity _JH_C is important for magnet materials with low resonance and high coercivity, e.g. BaFe. _JH_C results from the hysteresis loop.

The permeability is the "magnetic conductivity". For almost all magnet materials, the permeability is only slightly less than for air, while for iron it may reach more than a thousandfold.

The temperature coefficient indicates the reversible decrease of the remanence, based on normal room temperature (20°C) in percent per 1 °C increase in temperature.

The max. temperature is only an approximate value as it depends upon the dimensions of a magnet system (L/D-ratio). The given value can only be reached if the product of B and H reach a maximum (see magnetic design).

The density or the "specific weight" is given in g/cm³.

If the Curie temperature is reached every magnetic material loses its magnetism.