Patent ID: 7786637

Claim:
A touchdown bearing for use in a turbo-molecular pump, comprising: a rotor supported by a magnetic bearing, wherein, only at a time of stop of the rotor or at a time of abnormal rotation, an inner ring or an outer ring contacts the rotor to support the rotor, wherein a calcium zinc phosphate coating is formed on at least one of surfaces of a plurality of members that forms the bearing and contacts other members, microscopic pits and projections due to crystal grains of the calcium zinc phosphate coating are formed on a surface of the calcium zinc phosphate coating, and a molybdenum disulfide coating is formed on the surface of the calcium zinc phosphate coating on which the microscopic pits and projections are formed, wherein the touchdown bearing comprises a full complement ball bearing, wherein the plurality of members comprise a plurality of balls, wherein the plurality of balls are made of high speed tool steel, wherein the calcium zinc phosphate coating is formed on a surface of the plurality of balls, and wherein the molybdenum disulfide coating is formed on the calcium zinc phosphate coating.