Abstract
Increasing gear performance through applying a thin film coating on gear tooth flanks is attracting considerably attention. Several different gear tests show an increase in carrying load capacity or prolonged lifetime with tungsten-carbide doped DLC (W-DLC) coated gears, however the exact mechanisms by which the performance additives work in lubricated W-DLC coated contact are still unclear. In general, there are no guidelines for selection of lubricant for coated machine components subjected to high loads. The conventional lubricants have been primarily developed or tailored to interact with ferrous materials and are probably far from optimal for amorphous carbon-based coatings. In this paper, several different base oils and functional oil blends with single additives were tested on a ball-on-disc test rig with W-DLC/W-DLC coated specimens. One perspective oil blend was identified and was subjected to the further investigation on FZG gear test rig. Under conditions of reduced oil immersion depth scuffing load carrying capacity was determined.
