Use of zirconium balls in emergency bearings of turbomolecular pumps with magnetic bearings

摘要

The vacuum pump consists of a rotor turning inside a stator with a magnetic radial bearing which has rotor (12) and stator (13) rings with inner stainless steel races for balls (14a, 14b, 14c, 14d). At least some of the balls have an outer surface of zirconium dioxide for mechanical strength and to protect against chemical attack. Variants of the design can have solid balls of zirconium dioxide that can alternate with stainless steel balls, with both sets of balls having the same diameter for operating at normal temperatures.