Nanostructured Protective Coatings

Abstract : Recent developments in the field of "superhard" coatings are of interest to the Air Force for their potential superior wear resistance properties. The Nanostructured Protective Coatings (NPC) program was designed to establish a collaborative team of three entities having complementary hard materials competencies. The long-term goal was to enhance the fundamental understanding of superhard coatings and utilize this understanding to develop practical coatings needed by the Air Force. Work during the first phase focused on the two component system of nanocrystalline titanium nitride (nc- TiN) and amorphous silicon nitride (a-SiNx) where remarkable hardness values (45-80GPa) were first reported. Because scale-up to industrial-scale processes is the long-range goal of the program, the emphasis has been on physical vapor deposition (PVD) rather than the chemical vapor deposition (CVD) methodologies. The objectives of the first phase were accomplished, particularly in enhancing the understanding of PVD parameters, depositing coatings on practical substrates such as the Ti6Al4V used for turbine blades, and developing a versatile laboratory-scale erosion test relevant to this application.