Demonstration of Graded Nanocomposite Coatings For Robust Gears and Bearings

The Air Force requires technologies that will improve the performance and lifetime of emerging bearing and gear materials used in complex jet-engine nozzle and lift/vectoring components. Stringent operating requirements indicate these alloys may degrade from PFPAE lubricant fouling, require surface strengthening, and require an improvement in high-temperature friction/wear resistance. The team of Engineered Coatings, Inc., CSM/CSU, and lubricant formulator DuPont propose to demonstrate a multifunctional thin-film coating for advanced gear/bearing steels. We propose to investigate: 1) amorphous nanocomposite SiC/Ni coatings, which should offer good corrosion resistance to PFPAE and chloride salt-fog and demonstrated durability to high contact stress and 2) either SiC or TiC / a-C:H nanocomposite coating which has been demonstrated by ECI to provide excellent toughness and dry-sliding wear resistance through a graded coating architecture. Coated coupons will be screened in PFPAE oil at elevated temperature to establish corrosion resistance. Standard tests will include scratch, indentation, friction/wear and RCF in PFPAE fluid to establish tribological performance under simulated operating conditions. A gear section will be coated to demonstrate tooth root coverage from an unbalanced magnetron source for the metal species in the background gases. Hohman Plating will serve as our larger coating vendor with established quality control/assurance programs.