Thick PVD Cermet and Graded DLC Coatings for Lubrication-Free Weapon Parts

Engineered Coatings, Inc. (ECI) and Southwest Research Institute (SwRI) propose to investigate thick ceramic & metal (cermet) and semiconductor or metal-doped diamondlike carbon (DLC) physical vapor deposited (PVD) coatings over thick PVD metal underlayers as low-friction, corrosion-resistant surfaces for small-arm weapon components. Engineered Coatings and SwRI plan to mitigate the issues with electro and electroless-deposition coatings (e.g., tensile residual stress, reduced adhesion/durability and hazardous effluents) by using dry PVD processing and coating-compositional-grading to control coating stress and thus improve coating adhesion/toughness and durability. In addition, using a thick, dense PVD metal barrier underlayer will eliminate migration of the corrosion solution to the underlying substrate. Doping of DLC coatings will substantially improve coating adhesion/toughness without appreciably affecting the inherent low-friction solid lubricating and wear-resistant behavior. In addition, SwRI will investigate plasma ion immersion processing (PIIP) as a non-line-of-sight method with integral ion implantation followed by coating growth to ensure good coating adhesion. Coatings will be tested for corrosion resistance by salt-fog immersion and mechanical/tribological performance by scratch, indentation, and ball-on-disk friction/wear testing (in dry and contaminated oil). Weapon component parts will be demonstration-coated in the Phase I option program.