GOALI: Ultra-Low Wear Plasma Enhanced Atomic Layer Deposited Nitride Thin Films: Exploring Processing, Structure, Properties and Mechanisms

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Friction and wear of materials accounts for enormous losses in performance and lifetime of materials, devices and structures, at considerable cost to the US manufacturing, energy, and infrastructure sectors. Approaches to mitigate friction and wear are thus beneficial to the US economy. This Grant Opportunities for Academic Liaison with Industry (GOALI) award supports scientific research to understand mechanisms of friction and wear in metal nitride coatings. Preliminary studies revealed metal nitride coatings are among the most wear-resistant materials ever discovered, showing promise for significantly reducing the financial and environmental impacts of wear. In this research project, thin layers of metal nitride compounds are synthesized and their friction and wear properties are investigated. The aim of this work is to identify the relationships between how the films were created (processing) and their wear behavior (properties). Understanding these relationships allows for enhanced control of the mechanical behavior, and can lead to high-performance wear-resistant materials for coatings. The new materials developed are of broad importance for increasing efficiency and lifetime of mechanical systems, on both large and small scales. The work is performed in collaboration with an industrial partner, Veeco CNT. The industry team is integrally involved in the studies, which provides both educational opportunities for students involved in the research and a path to commercialization for high-performance wear-resistant coating materials. This research examines the fundamental relationships among processing, microstructure, and mechanical behavior in a class of transition metal nitrides deposited using plasma-enhanced atomic layer deposition. The high degree of synthetic tunability in this deposition technique allows for tailoring of the film composition and microstructure. Specifically, the fundamental role of composition on wear mechanism is investigated to determine the role of solid solution strengthening versus the formation of a lubricious wear-generated film in films with both vanadium and titanium cations. The impact of crystallite size on mechanical properties is determined for crystallite sizes in the 1-30 nm range using four independent synthesis parameters that control crystallite size. Adhesion and interface chemistry between the nitride films is investigated and related to macroscopic mechanical behavior, such as delamination, that is relevant to applications. Taken together, these studies reveal fundamental wear mechanisms of this highly promising material that can be related directly to the synthesis and processing parameters.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.