The Gem Of Magnetic Fluids

The Gem Of Magnetic Fluids

Ahmed Al-Jamel

1.1 PRELUDE:

The phenomenon of ferromagnetism is associated only with the solid state of matter; like iron, nickel, cobalt and some rare earth metals and their alloys. Thus, up to now, there is no intrinsic homogeneous fluid having ferromagnetic properties; although, theories admit the possibility of ferromagnetism in the liquid state, and suggest that there is no inherent reason why they should not exist [1-3,5]. Ferromagnetism occurs when paramagnetic ions in a solid lock together in such a way that their spins all point (on the average) in the same direction . At a certain temperature this locking breaks down and ferromagnetic materials become paramagnetic. This transition temperature is called the Curie point (TC), which is invariably well below the melting point of the corresponding material [1,8,12].

1.2 MAGNETIC FLUIDS:

Magnetic fluids ( MF ) are stable colloidal suspensions of ultrafine ferro- or ferri- magnetic particles ( D100Ao ), coated with a surfactant like oleic acid, in a suitable liquid carriers such as Isopar-M, kerosene, decalin, etc., [1,2].

The idea of MF was put forward independently and almost simultaneously by several investigators. The first prepared MF was developed by Stephen Papell of the National Aeronautics and Space Administration (NASA) in the early 1960s. After that, Ronald E. Rosensweig and his colleagues succeeded in formulating MFs that were 10 times as strong magnetically as Papell`s orig...

The Gem Of Magnetic Fluids

Login

Join