Functionally Graded, Nanocrystalline, Multiphase, Boron- and Carbon-Based Superhard Coatings--Spire Corporation, One Patriots Park, Bedford, MA 01730-2396; 781-275-6000
Dr. Fereydoon Namavar, Principal Investigator
Dr. Richard S. Gregorio, Business Official
DOE Grant No. DE-FG02-99ER82891
Amount: $749,921

Industrial and medical components require harder surfaces to increase durability and life. Attempts to coat metallic components with diamond or ceramic films, such as for earth drilling equipment, have failed due to the poor adherence of dissimilar materials and the brittleness of the films. This project will fabricate functionally graded, nanocrystalline, multiphase, superhard, adherent, low-friction, metallo-ceramic protective coatings. The nanocrystalline and multiphase structures reduce internal stress and enhance coating toughness. Due to the grading, the coatings will have metallic adherence to metal substrates, but posses ceramic-like wear resistance at the surface. The Phase I project demonstrated the fabrication of functionally graded, Ti/TiN/TiBN nanocrystalline multiphase (TiN, TiB₂ and BN) coatings with a hardness of 42 Gpa. The graded structure provided a gradual transition from metallic to covalent bonding through the thickness of the film, thereby enhancing adhesion. Wear resistance evaluation (pin-on-disk) for 5 million cycles (25 days) at 1 Gpa contact stress showed no wear, indicating the potential for the coating to extend the lifetime of substrate materials by several orders of magnitude. The Phase II project will fabricate and optimize nanocrystalline multiphase (Ti-B-C-N) graded layer structures. The ratios between the various film constituents (TiN, TiB₂, B₄C, BN) will be precisely controlled and related to adhesion, internal stress, hardness, and wear resistance. The coating will be deposited on earth drilling components and will be evaluated for incorporation into drilling products.

Commercial Applications and Other Benefits as described by the awardee: These coatings will find a wide market, particularly as protective coatings for engine components (turbine blades), orthopedic prostheses, other medical devices, and drilling equipment. A major supplier of earth drilling equipment (with a market share of about $1billion per year) will participate as a scientific and commercial partner in Phases II and III.