A method and apparatus is provided for allowing a molecularly thin film to
be established on a surface of the gas fluid dynamic bearing. The film can
be controllably replenished so that the problem of liquid lubricant
starvation is overcome. A suitable non-sludging lubricant of low surface
tension is held in a porous reservoir within the stationary portion of the
bearing. This fluid migrates out of the reservoir to coat the contiguous
bearing surfaces. Alternatively, the lubricant may be held in a porous
reservoir within the rotating portion of the bearing; due to centrifugal
force, as the rotating portion spins, the fluid is spun out and coats the
opposite non-rotating surface. The reservoir may be replaced by a singular
reservoir such as a simple hole, depression, cavity or groove filled with
lubricant. The liquid may also migrate by capillary force through natural
surface asperities or roughness by texturing the surface to promote
capillary migration; or the distribution of the lubricant is accomplished
by evaporation and condensation. The reservoir may be located in a region
of the bearing that reaches a relatively higher operating temperature than
the wear surfaces of the bearing. The transport of the lubricant then
occurs by evaporation at the warmer reservoir, and condensation at the
cooler bearing surface.
