Designing Ultra-hard Coatings of Q-carbon and Diamond Related Materials

North Carolina State University, Raleigh NC

Investigators

Abstract

NON-TECHNICAL DESCRIPTION: Ultrahard protective coatings are critical in applications ranging from microelectronics packaging to cutting tools needed for oil and gas extraction and high-speed machining. Performance improvement directly scales with the hardness enhancement of protective coatings. This proposal focuses on design and synthesis of ultrahard materials, striving to be harder than diamond — the hardest material known so far. By using a novel approach based upon rapid laser melting and quenching, it is possible to create diamond or new Q- phases of carbon which are significantly harder. Since this process can be performed at ambient temperatures and pressures, there is a significant reduction in energy usage and manufacturing of Q-carbon and diamond-related materials. This research is being integrated with the curriculum development and related educational activities, such as M.S. Nano program. The proposal addresses training of graduate and undergraduate students in collaboration with ORNL, Kopin Corporation and NC A&T to attract minority students into the graduate studies. TECHNICAL DETAILS: Diamond and Q-phase related materials are synthesized by nanosecond laser melting of carbon films and rapid quenching from the undercooled state. The degree of undercooling determines this direct conversion into diamond or Q-carbon or a mixture of the two. Modeling is carried out to understand laser-solid interactions and correlations between hardness and number density of atoms. In this project, different Q-carbon and diamond mixtures are synthesized by controlling laser, film and sapphire substrate variables. These phases are characterized by using high-resolution electron microscopy, electron-energy-loss spectroscopy and Raman techniques, and direct correlations with enhanced hardness and toughness established. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.