Static pressure gas bearing assembly

A static pressure gas bearing assembly, comprising:

• a porous graphite member disposed to provide a bearing surface;
• and
• means for supplying a gaseous fluid to said porous graphite member so that the gaseous fluid is discharged from said bearing surface of said porous graphite member;
• wherein said porous graphite member has a degree of swelling of not more than 0.02% when the degree of swelling is defined by the following equation:
• S={(Lw-Ld)/Ld}.times.100
• where S is the degree of swelling, Ld is the size of a test piece which is in a dry state, and Lw is the size of the test piece when it is a wet state.

A combination, comprising:

• a static pressure gas bearing assembly;
• and
• a member to be supported by said bearing assembly,
• wherein said bearing assembly includes a porous graphite member disposed to provide a bearing surface, and means for supplying a gaseous fluid to said porous graphite member so that the gaseous fluid is discharged from said bearing surface,
• wherein said member to be supported has a titanium nitride film formed on the surface thereof to be opposed to said bearing surface of said porous graphite member, and
• wherein said porous graphite member is made by molding, calcining and graphitizing carbon particles, having particle diameters distributed in a range not more than approximately 40 microns, such that a number of pores are substantially uniformly distributed in said porous graphite member.

A combination, comprising:

• a static pressure gas bearing assembly;
• and
• a member to be supported by said bearing assembly,
• wherein said bearing assembly includes a porous graphite member disposed to provide a bearing surface, and means for supplying a gaseous fluid to said porous graphite member so that the gaseous fluid is discharged from said bearing surface,
• wherein said member to be supported has a titanium nitride film formed on the surface thereof to be opposed to said bearing surface of said porous graphite member, and
• wherein said porous graphite member is made by molding, calcining and graphitizing carbon particles having particle diameters not more than approximately 40 microns, with approximately 80% of the carbon particles having particle diameters ranging from 1 to 20 microns, such that a number of pores are substantially uniformly distributed in said porous graphite member.

A combination, comprising:

• a static pressure gas bearing assembly;
• and
• a member to be supported by said bearing assembly;
• wherein said bearing assembly includes a porous graphite member disposed to provide a bearing surface, and means for supplying a gaseous fluid to said porous graphite member so that the gaseous fluid is discharged from said bearing surface,
• wherein said member to be supported has a titanium nitride film formed on the surface thereof to be opposed to said bearing surface of said porous graphite member, and
• wherein said porous graphite member has a degree of swelling of not more than 0.02% when the degree of swelling is defined by the following equation:
• S={(Lw-Ld) /Ld}.times.100
• where S is the degree of swelling, Ld is the size of a test piece which is in a dry state, and Lw is the size of the test piece when it is in a wet state.