METHOD OF PREPARING MAGNETOSENSITIVE SUSPENSION FOR VIEWING MAGNETIC FIELDS FOR RECORDING AND MAGNETIC-TAPE TESTING Russian patent published in 2010 - IPC H01F1/28 

FIELD: physics.

SUBSTANCE: to prepare magnetosensitive suspension, magnetic liquid of the magnetite type in kerosene is dried for a long period of time at room temperature. The crushed dry residue is added to water, after which ultrasonic dispersion is carried out while adding a surfactant (sodium oleate) to prevent coagulation. A thin layer of the magnetosensitive suspension is deposited onto a magnetic recording medium. The effect of the uniform magnetic field gives rise to ponderomotive forces acting on the magnetised particles. The latter move in the direction of increase of magnetic induction, i.e. are pulled and fall in the region with a stronger field, which can be viewed. During magnetic-tape testing, a thin layer of the magnetosensitive suspension is poured into a dish in form of an aluminium ring with diametre of 2 cm, attached to one side of the thin film. The dish is placed on the analysed ferromagnetic object which is magnetised by a permanent magnet. Magnetograms of the analysed specimens are viewed.

EFFECT: reduced material and time expenditure, increased stability, useful life and resolving power of the magnetosensitive liquid.

2 cl, 3 dwg