Seizure Resistance of Thermally Diffused Ball after Sn-Plating in Four-Ball Test : Case of Grease with Molybdenum Disulfide Additive

Abstract

To clarify the seizure resistance of stainless steel balls of which the surface layer was thermally diffused after being Sn-plated, a four-ball test was carried out with grease lubrication. From the tests, the following results were obtained. The diameter of the wear scar of the ball lubricated with the grease containing a molybdenum disulfide additive was smaller than that of the ball lubricated with the grease without the additive, and the diameter of the wear scar increased with increasing concentration of the additive. The load at the incipient stage of seizure of the ball of which the diffused surface layer was about 6 μm thick was 2∼4 times larger than that of the ball without the diffused surface layer. Further, it was found that the seizure resistance of the balls could be estimated from the critical surface temperature and that the critical temperature increased with increasing concentration of the additive.