FRICTION AND WEAR OF BALL BEARINGS IN LIQUID SODIUM.

An experimental study on the friction and wear properties of ball bearings has been conducted in liquid sodium at 400°C. Out of a number of materials compatible with sodium, Stellite 6, Hastelloy C and austenitic stainless steel (AISI 316) were chosen. A medium size, single-row, deep groove, radial type ball bearing was selected for the form of test bearings. The following conclusions were obtained from this study: (1) Of the three materials, the hardest material (Stellite 6) showed the highest resistance against wear, and the greatest recovery effect from friction. (2) Liquid sodium appears to contribute little as lubricant, due to its low viscosity and extremely high chemical activity. No tendency toward self-welding was, however, observed at temperatures up to 400°C, despite the mean compression stress applied having been over three times the yield strength. (3) The wear of ball bearings in liquid sodium is considered to be caused by local sliding friction. The wear rate is higher the softer the materi...