Developed in the 1970s, ferrofluidic seals have been utilized in various specialized applications, including computer disk drives, vacuum systems, and nuclear technologies.
The ball bearings provide two functions: maintaining the shaft's centering within the seal gap and supporting external loads.
The bearings are the only mechanical wear items, as the dynamic seal is formed with a series of rings of ultra-low vapor pressure, oil-based liquid, held magnetically between the rotor and stator.
Ferrofluid-sealed feedthroughs can operate in environments including ultra-high vacuum (below 10−8 mbar), temperatures over 1,000 °C, tens of thousands of RPM, and multiple-atmosphere pressures.
Necessary features may include multiple ferrofluid stages, water cooling, customized materials, permanent magnets, and exotic bearings.