Nanocrystalline Superhard, Ductile Ceramic Coatings for Roller Cone Bit Bearings

41126 November 20, 1996 Spire Corporation Ultra-fine-grained ceramics possess extraordinary properties which include increased ductility and decreased permeability, thus improving their effectiveness as a protective coating. When crystallites are smaller than 10 nm, these coatings demonstrated an increase in hardness about 2-3 times greater than those with larger crystallites. Phase I will demonstrate the advantage of nanocrystalline ceramics as a protective coating for metals and compare them to ceramics which consist of microcrystals. Nano-size crystallite films will be fabricated using ion beam assisted deposition, and the relationship between crystallite dimension and mechanical film properties (hardness, wear resistance, friction, and ductility) will be investigated. Phase II will further investigate the effect of nanostructures and relate them to ductility and shock resistance, optimize deposition, and demonstrate the technology on high performance journal bearings. Commercial Applications and Other Benefits as described by the awardee: Superhard, ductile, nitride coatings would significantly extend the life time of critical bearings in bits used in rock drilling applications. The hard, ductile films could also be used to reduce friction (allowing energy saving redesign) of components such as gears and bearings in other (e.g., transportation) applications.