| 摘要 |
The present invention is a method for producing a fluid dynamic pressure bearing made of powder sintered metal and that grooves for generating dynamic pressure are formed on an inner peripheral surface and whose object is to facilitate forming a ferrosoferric oxide (Fe3O4) membrane on a surface of a bearing material, the method comprising compacting metal powder including at least not less than 70% by weight of particles with diameters of not more than 45 μm to gain a bearing material, sintering said bearing material, forming grooves for generating dynamic pressure on said sintered bearing material, and performing steam treatment to said sintered bearing material with said grooves to form a ferrosoferric oxide (Fe3O4) membrane on a porous surface of an inner surface or on porous surfaces of an inner surface and both end surfaces, so that gaps between particles become small because diameters of the particles of material powder of a powder sintered bearing material are approximately even and fine and are even small pores, as a result, sealing pores on the surface due to steam treatment is easy and dynamic pressure cannot be leaked.
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