SBIR Phase I: Carbon Nitride for Superhard Coatings

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This Small Business Innovation Research Phase I project will synthesize a C3N4 phase and develop a method to stabilize the C3N4 films. The hardest material which can be synthesized is based on a combination of B, C, and N. However, materials and compounds based on these elements are metastable at standard pressures and temperatures. Therefore, one needs a novel, non-equilibrium method to process and synthesize them. The firm has developed such methods, including ion beam assisted deposition (IBAD) and deposition from electron cyclotron resonance (ECR). (C3N4 should be harder than diamond. The synthesis of C-N films with a hardness about half that of diamond and a smoothness of about 0.5 nm has been documented. These films were adherent on most substrates, including steel and magnetic thin-film materials (as in computer disks), however, no direct evidence of a carbon nitride phase was demonstrated. IBAD is an advanced, low-temperature, thin-film deposition process combining evaporation with simultaneous ion bombardment; it is capable of depositing adherent films on virtually any substrate. The Phase I project will deposit carbon nitride films using IBAD with an ionized-vapor source for carbon. Ionizing both carbon and nitrogen would enhance the probability of forming carbon nitride films. Stress is the major obstacle in the formation of thick films with the theoretically expected hardness value; stress reduction will be addressed by a number of methods, including the introduction of a third element such as boron. A process designed to deposit super-hard films on essentially any shape substrate has extremely high commercial promise. Carbon nitride films are inexpensive, extremely hard and scratch resistant, and easily applied to metal surfaces or polymers.