Dilution Stable Water Based Magnetic Fluids.
Khalafalla-SE; Reimers-GW; Rholl-SA
U S Pat 4 208 294 1980 Jun; :
A dilution-stable water-based ferrofluid is made by dispersing magnetic particles in water with the aid of a c12-c15 aliphatic monocarboxylic acid. The magnetic particles are preferably particles of magnetite, prepared by the precipitation of dissolved iron chlorides from aqueous solution using ammonia. The preferred acids used in preparing the dispersions are dodecanoic (c12) and tridecanoic (c13). For example, a magnetic fluid that can be diluted with water at a 50:1 ratio without flocculation was obtained by adding dodecanoic acid 4.8 G to a precipitate obtained by adding concentrated nh4oh 50 ml to a 50 ml solution of fecl2.4H2o 12 g and fecl3 24 g.
U.S. Pat. 4,208,294; June 17, 1980; Chem. Abstr. 91:221,542J