METHOD OF PRODUCING WATER-BASED FERROMAGNETIC LIQUID Russian patent published in 2013 - IPC H01F1/28 

FIELD: chemistry.

SUBSTANCE: method of producing ferromagnetic liquid involves depositing magnetite, stabilisation thereof with a surfactant in aqueous acetic acid solution while heating and stirring, treating the stabilised magnetite with a solvent while monitoring full removal of ion salts and excess surfactant, peptisation in a nonpolar dispersion medium (water), wherein treatment of the stabilised magnetite is carried out while heating and stirring with a nonpolar solvent first and then with a polar solvent, and stabilisation of the magnetite is carried out with a non-ionic surfactant first and then with an anionic surfactant. The ratio of the nonionic surfactant - stearic acid anhydride in stearic acid solution to the anionic surfactant - sodium stearate is equal to 1:1. Peptisation of the stabilised magnetite is carried out at temperature of 60°C for 2 hours.

EFFECT: high aggregative stability, low viscosity and high saturation magnetisation of the obtained liquid.

5 cl