Ferromagnetic material properties

The article Ferromagnetic material properties is intended to contain a glossary of terms used to describe (mainly quantitatively) ferromagnetic materials, and magnetic cores. == Terms == Hysteresis loop Induction B as function of field strength H for H varying between Hmin and Hmax; for ferromagnetic material the B has different values for H going up and down, therefore a plot of the function forms a loop instead of a curve joining two points; for perminvar type materials, the loop is a "rectangle" (Domain Structure of Perminvar Having a Rectangular Hysteresis Loop, Williams, Goertz, Journal of Applied Physics 23, 316 (1952); in fact it is rectangle if B-μ0H is used instead B on the plot); Remanence, Br; "induction which remains" After magnetization to saturation, a value of induction B in the material in a closed magnetic circuit without external field H; the point where hysteresis loop crosses B axis; Coercivity, Hc After magnetization to saturation, a value of field strength H at which induction B in the material becomes 0; the point where hysteresis loop crosses H axis; Maximum energy product, (BH)max Largest possible field of a rectangle on the hysteresis loop plot, which has two edges on the B and H axes, and a vertex on the hysteresis loop in the second quadrant (B positive, H negative); range from below 1 J/m3 for some soft materials (permalloy, 3E4 ferrite), to above 400 kJ/m3 for hard ones (neodymium magnets); Magnetic viscosity When an external field H is changed, and then kept at a new value, the induction B first changes almost at once, then some smaller change of B follows in a time; for a permanent magnet typically the time dependence is B(t) = B(t0) − S·ln(t/t0), where t is time since H change, t0 is some reference time, and S is a constant of the process (but not of the material, as it varies with magnitude of the H and its change); a theory describing this kind of time dependency was developed by Louis Néel (J. de Phys.

Source: Wikipedia — Ferromagnetic material properties (CC BY-SA 4.0)

Ferromagnetic material properties

The article Ferromagnetic material properties is intended to contain a glossary of terms used to describe (mainly quantitatively) ferromagnetic materials, and magnetic cores. == Terms == Hysteresis loop Induction B as function of field strength H for H varying between Hmin and Hmax; for ferromagnetic material the B has different values for H going up and down, therefore a plot of the function forms a loop instead of a curve joining two points; for perminvar type materials, the loop is a "rectangle" (Domain Structure of Perminvar Having a Rectangular Hysteresis Loop, Williams, Goertz, Journal of Applied Physics 23, 316 (1952); in fact it is rectangle if B-μ0H is used instead B on the plot); Remanence, Br; "induction which remains" After magnetization to saturation, a value of induction B in the material in a closed magnetic circuit without external field H; the point where hysteresis loop crosses B axis; Coercivity, Hc After magnetization to saturation, a value of field strength H at which induction B in the material becomes 0; the point where hysteresis loop crosses H axis; Maximum energy product, (BH)max Largest possible field of a rectangle on the hysteresis loop plot, which has two edges on the B and H axes, and a vertex on the hysteresis loop in the second quadrant (B positive, H negative); range from below 1 J/m3 for some soft materials (permalloy, 3E4 ferrite), to above 400 kJ/m3 for hard ones (neodymium magnets); Magnetic viscosity When an external field H is changed, and then kept at a new value, the induction B first changes almost at once, then some smaller change of B follows in a time; for a permanent magnet typically the time dependence is B(t) = B(t0) − S·ln(t/t0), where t is time since H change, t0 is some reference time, and S is a constant of the process (but not of the material, as it varies with magnitude of the H and its change); a theory describing this kind of time dependency was developed by Louis Néel (J. de Phys.

Source: Wikipedia "Ferromagnetic material properties" · CC BY-SA 4.0

Share this article: X · Bluesky
Privacy Policy