Iron based powder materials were put in appearance at the beginning of 20th century as a result of researching works coupled with a necessity to transmit telephone signals for maximum distances with lowest attenuations for a coil loading of telephone cables. At the beginning of 1902, a patent for inductance coils made of finely dispersed powder iron combined with a mixture for isolation of particles, was granted to Frederic Dolesalek, leading engineer of Siemens & Halske Co. Industrial production of sprayed iron based ring-shaped products was firstly started by Western Electric Co. in 1916. At beginning of 1921, up to 25 000 pounds of powder iron were produced weekly at the factory of this company in Illinois. By beginning of 21th century, powder iron cores found a wide application in different electronic devices.
Powder iron cores have lowest price as compared with other types of powder materials. The losses that are highest as compared with other classes of powder materials may be compensated by a use of larger standard sizes. In many applications where a size of wound product and its high heating temperature is not important and a saving in prices of ready-made wound product is important, a preference may be given to a use of inexpensive cores based on sprayed iron.
Powder iron cores are issued with initial permeability of up to 100 and have a high saturation magnetic flux density from 1.0 to 1.5 T (depending on mixture brand). In pulse power supplies, materials consisting of "26" mixture (μi = 75), "52" mixture (μi = 75) and "18" mixture (μi = 75) are generally used.
Sprayed iron based cores may be successfully used as magnetic circuits in:
- low-frequency output direct current chokes;
- power correction chokes;
- resonance inductance coils;
- input noise filters;
- accumulative chokes;
- light regulation chokes.
Configurations
There is a great configuration variety of cores made of sprayed iron. Due to a lowest stray inductance and to an absence of necessity to use additional measures for protection from occurring disturbances, in vast majority of cases sprayed iron based ring-shaped cores are used. In cases when requirements for occurring electromagnetic disturbances and for electromagnetic compatibility are not of critical importance, for reducing a price of ready-made wound product more complex configurations of cores (for example, dumb-bell and rod-shaped) of sprayed iron are used.
- Powder Iron Ring-Shaped Cores.
- Dumb-bell configured Powder Iron Cores.
- Sprayed Iron Based Rod-shaped Powder Cores.
