Friction and wear of electroless Ni alloy plated gear under non-lubricating condition in high vacuum

A gear test and a two-cylinder test were carried out under non-lubricating condition in high vacuum to investigate the friction and wear behaviors of electroless Ni based alloy plated gears in vacuum. The gear test results were compared with the two-cylinder test results. 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 PTEE 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 cylinders 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.