METHOD OF PREPARING FERROMAGNETIC LIQUID Russian patent published in 2011 - IPC H01F1/28 H01F1/44 

FIELD: chemistry.

SUBSTANCE: invention relates to colloidal chemistry and can be used to prepare magnetic liquid used in tilt sensors, accelerometers etc. The method involves precipitation of finely dispersed magnetite, treatment of the magnetite precipitate for 15 minutes with 50% aqueous solution of acetic acid at temperature 80±2°C and rate of stirring the suspension not less than 1500 rpm, stabilisation of the magnetite with a surfactant while heating and stirring, monitoring complete removal of iron salts and excess content of the surfactant, dissolving the stabilised magnetite in a reference liquid in a vacuum while heating and stirring at a rate of not less than 1500 rpm. The surfactant used is oleic acid heated to temperature of the water-acetic suspension of magnetite. After stabilisation and each washing cycle, the magnetite undergoes magnetic separation. The reference liquid used is jet fuel with an ethyl cellosolve additive.

EFFECT: invention provides low viscosity of magnetic liquid in the entire range of working temperatures and high saturation magnetisation, as well as stability of these properties over time.

1 ex