Abstract: A magneto-fluidic seal includes a shaft; a sleeve surrounding the shaft; a housing made of soft magnetic material surrounding the sleeve; a magnet conducting a magnetic flux to the sleeve; and a magnetic fluid in a gap between the sleeve and the shaft, and/or in a gap between the sleeve and the housing. Optionally, the sleeve includes a channel on a longitudinal side, and wherein the magnet is positioned in the channel. The channel can be substantially circular or polyhedral. The magnet is preferably offset from a bottom of the channel, and oriented radially. Preferably, the magnet includes a plurality of segments, or flat plate-shaped magnets, arranged substantially evenly and circumferentially around the shaft.

Abstract: The present approach pertains to colloidal chemistry and methods of manufacturing magnetic fluid such as ferrofluid. In particular, the present approach is directed to methods of manufacturing magnetic fluid that is resistant to aggregation and clumping, and is more stable over time. The process according to the present approach comprises sedimentation of magnetic particles; mixing the magnetic particles with an aqueous acetic acid solution, a surface-active agent and a polarizing composition; applying pulsed magnetic fields; removing excess surface-active agents and polarizing composition; ferrite desalination; and peptization of the surface-active agent in a non-polar, dispersing fluid. Magnetic fluids made according to the process of the present approach can be used, e.g., for ferrofluidic seals, inclinometers, accelerometers, or as magnetic lubricants.

Abstract: The present approach pertains to colloidal chemistry and methods of manufacturing magnetic fluid such as ferrofluid. In particular, the present approach is directed to methods of manufacturing magnetic fluid that is resistant to aggregation and clumping, and is more stable over time. The process according to the present approach comprises sedimentation of magnetic particles; mixing the magnetic particles with an aqueous acetic acid solution, a surface-active agent and a polarizing composition; applying pulsed magnetic fields; removing excess surface-active agents and polarizing composition; ferrite desalination; and peptization of the surface-active agent in a non-polar, dispersing fluid. Magnetic fluids made according to the process of the present approach can be used, e.g., for ferrofluidic seals, inclinometers, accelerometers, or as magnetic lubricants.

Abstract: A magneto-fluidic seal includes a shaft; a sleeve surrounding the shaft; a housing made of soft magnetic material surrounding the sleeve; a magnet conducting a magnetic flux to the sleeve; and a magnetic fluid in a gap between the sleeve and the shaft, and/or in a gap between the sleeve and the housing. Optionally, the sleeve includes a channel on a longitudinal side, and wherein the magnet is positioned in the channel. The channel can be substantially circular or polyhedral. The magnet is preferably offset from a bottom of the channel, and oriented radially. Preferably, the magnet includes a plurality of segments, or flat plate-shaped magnets, arranged substantially evenly and circumferentially around the shaft.