NSF Award
9960578
Ultrahard materials (UHM) possess many superior properties, making them highly desirable as industrial materials. Unfortunately, these materials, particularly the hardest of all, diamond-like materials, cannot be used in many high-volume applications due to their low oxidation resistance, low thermal stability, and high cost. For this reason, new, low-cost UHMs with comparable or even superior properties are required. Calculations based on known thermodynamic and structural data predict that cubic carbon nitride, alpha-C3N4, will be significantly harder and much more thermally oxidation-resistant than diamond. Despite significant progress made by researchers over the last decade, the formation of pure phases of this material, as well as others like it, has not as yet been accomplished. In the project, Ultramet will generate novel UHMs such as alpha-C3N4, cubic carbonazenide (cubic C(HN)), and composite ternary nitrides consisting of metal nitride nanocrystals and an amorphous silicon nitride (Si3N4) phase using a novel chemical vapor deposition (CVD)-based process. This new process, which is kinetically driven, allows the formation of a large variety of ceramic materials at or near room temperature.<br/><br/>Applications: The proposed novel CVD processes will yield new UHMs such as alpha-C3N4, cubic C(HN), and composite ternary nitride/Si3N4 phases with hardness and oxidation stability equal to or exceeding those of cubic boron nitride and diamond. The new processes will allow these new UHMs to be produced at lower cost and used in a much wider range of applications than current UHMs.<br/><br/>Keywords: ultrahard materials, cubic carbon nitride, cubic carbonazenide, ternary metal nitrides, chemical vapor deposition, thin films, superabrasives
