Deposition and characterization of hybrid filtered arc/magnetron multilayer nanocomposite cermet coatings for advanced tribological applications

Abstract

The demand for low-friction, wear and corrosion resistant components, which operate under severe conditions, has directed attention to advanced surface engineering technologies. The large area filtered arc deposition (LAFAD) process has demonstrated atomically smooth coatings at high deposition rates over large surface areas. In addition to the inherent advantages of conventional filtered arc technology (superhardness, improved adhesion, low defect density), the LAFAD technology allows functionally graded, multilayer, and nanocomposite architectures of multi-elemental coatings via electro-magnetic mixing of two plasma flows composed of different metal vapor ion compositions. Further advancement is realized through a combinatorial process using a hybrid filtered arc–magnetron technique to deposit multilayer nanocomposite TiCrN + TiBC cermet coatings. Multiple TiCrN + TiBC coating architectures were reviewed for their ability to provide wear resistance for Pyrowear 675 and M50 steels used in aerospace bearing and gear applications. Coating properties were characterized by a variety of methods including SEM/EDS, HRTEM, and XRD. Wear results were obtained for high contact stress boundary lubricated sliding and advanced bearing simulation testing for wear performance under oil-off operating conditions. The best coating candidates demonstrated order of magnitude increases in resistance to sliding wear, and extended low friction operation during simulated oil-off events. Coating failure mechanisms were brittle in nature and suggestions are presented for the further optimization of TiCrN + TiBC coating architectures.