Low Friction Coefficient Electroplated Solid-Lubricant/(WC)Ni Nanocomposite Coatings for Transmission Gear Surfaces

The US Navy seeks none-line-of-sight deposition technologies to produce gear coatings to meet the Navy~{!&~}s loss-of-lubricant requirement. Current rotary platform drive trains, coated with black oxide, barely meet the loss-of-lubricant survivability requirement, and consequently require an expensive auxiliary lubrication system adding additional weight to the drive system. Inframat Corporation proposes to demonstrate the feasibility of generating a high performance nanoparticle strengthened Ni nanocomposite gear lubricant coating which exhibits high lubricity. A solid lubricant consisting of Fe3O4 nanoparticles will be electrochemically co-deposited in a Ni matrix. To further increase the wear resistance of the nanocoatings, a small fraction of WC (5-10%) nanoparticles will be added to this nanocomposite system. The proposed program will (1) prepare colloidal bath compositions containing Fe3O4/(WC) nanoparticles in a nickel solution, (2) deposit Fe3O4(WC)/Ni nanocoatings suitable for low friction coefficient gear surfaces, and (3) conduct tests to evaluate coating feasibility including coating uniformity, adhesion, microstructure, hardness, friction coefficient and wear characteristics under projected gear to gear tooth contact stresses and pitchline velocities. The proposed program builds on Inframat~{!&~}s extensive experience in self lubricant and nanocomposite coatings. The proposed lubricant nanocoating is expected to exhibit high adhesion strength, low friction coefficient, and prolonged service with low maintenance cost.