動圧気体軸受面へのスパッタリング (第2報)

Abstract

MoS2 dry lubricant film was deposited onto the surface of self-acting gas bearings by sputtering technique to improve the frictional properties for start-stop conditions. The sputtered MoS2 films (0.5-3 μm) were deposited on highly-finished metal surfaces. The low-speed sliding test shows that MoS2 films have a low coefficient of friction. To evaluate their lubricating properties for start and stop conditions, MoS2 films were deposited on spiral grooved thrust gas bearings (flatness of bearing surface 1 μm). Bearing coated with MoS2 film of more than 2 μm thickness could bear over 250 start-stop cycles. The frictional coefficient μ (calculated value from measured torque) of the MoS2 film coated bearings for start and stop conditions reached μ=0.3. Although the TiN film reported by the 1st report served mainly for surface hardening and prevention of surface damage, but the MoS2 film reported here was useful for improving the frictional property for start and stop conditions, particularly to decrease the starting torque. For practical use, TiN and MoS2 films were deposited onto the surface of self-acting gas bearings of a centrifugal helium compressor which operates in temperature about 80 K. These films showed the good friction and wear properties in low temperature operation.