Friction and Wear of Surface Modified Stainless Steel Gears and Rollers in High Vacuum

In this study the authors examined possibility of applying surface modification treatments frequently used under oil lubrication to gears in high vacuum. Friction and wear performance of surface modified spur gears and rollers made of stainless steel was investigated. A spur gear test and a two-cylinder test were carried out under non-lubricating condition in high vacuum to investigate friction and wear behaviors of surface modified gears in vacuum at room temperature. The gear test results were compared with the two-cylinder test results. Sulfurizing treatment, Sn plating with thermal diffusion, three kinds of electroless Ni based alloy platings, and two kinds of composite platings with dispersed particles were employed here. In case of the Ni-P alloy plated gear with dispersed PTFE particles, the wear was almost uniform along the tooth profile and the fluctuation of the dynamic load was small. In cases of the Ni-B alloy plating, the Ni-P-B alloy plating and the Ni-P alloy plating with dispersed BN particles, the wear of the gear pairs was large, while the wear of the rollers was rather small. Though the wear in the two-cylinder test was much smaller than that in the gear test, the average friction coefficients in both the two tests were almost the same with each other.