Low cost method for manufacturing ferrofluid
AssigneeFerrofluidic Corporation
InventorsKuldip Raj, Lutful M. Aziz
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Abstract
A ferrofluid manufacturing process applies energy to a nonmagnetic .alpha.-Fe.sub.2 O.sub.3 starting material to render it magnetic and suitable for use in a ferrofluid. The material is placed, together with a solvent and a surfactant, in a commercial attrition mill where the mill action converts the non-magnetic particles to magnetic particles. In order to eliminate a solvent replacement step which is necessary with oil carrier liquids, water is used as the grinding solvent and as the ferrofluid carrier liquid. The resulting water-based ferrofluid has a high saturation magnetization, low viscosity and good colloidal stability. Using the inventive method, a large volume of fluid can inexpensively be synthesized in a short time.
Claims12
A method for making a ferrofluid, the method comprising the steps of:
- (a) combining particles of .alpha.-Fe.sub.2 O.sub.3, water and a lignosulfonate-based surfactant to form a slurry;
- (b) placing the slurry in an attrition mill;
- and
- (c) operating the attrition mill for a period of time sufficient to convert the .alpha.-Fe.sub.2 O.sub.3 particles to magnetic iron oxide particles.
A method for making a ferrofluid, the method comprising the steps of:
- (a) forming a slurry which is, by weight, 19.4% .alpha.-Fe.sub.2 O.sub.3 powder, 73.3% water and 7.3% sodium salt of lignosulfonic acid;
- (b) placing the slurry in an attrition mill;
- and
- (c) operating the attrition mill for a period of time sufficient to convert the .alpha.-Fe.sub.2 O.sub.3 particles to magnetic iron oxide particles.
Dependencies are inferred from the claim text.