GOALI: Understanding Tribological Properties of Thermally-Synthesized Carbon

This Grant Opportunity for Academic Liaison with Industry (GOALI) award will support fundamental tribochemistry research that will elucidate the friction and wear behaviors of carbon materials. Carbon blocks and coatings are widely used to control friction and wear of sliding interfaces in manufacturing processes or manufactured goods. This project focuses on understanding and improving tribochemical properties of thermally-synthesized carbon (TSC) materials for the application where low friction is beneficial. Polycrystalline graphite powders and other TSC materials show relatively high friction, although superlubricity is readily observed on the basal plane of graphite and for hydrogenated diamond-like carbon produced via plasma enhanced deposition process. This raises an important question – what controls superlubricous behaviors of different types of carbon materials? Addressing this question can lead to a better design of carbon materials that can be used as carbon brushes for electrical motors or generators and/or mechanical seals in which oil or grease lubrication cannot be employed. Reduction of friction and wear of these components will greatly improve energy efficiency in manufacturing processes. These issues are important in new energy applications and hence US competitiveness. Morgan Advanced Materials is participating as the GOALI partner and will provide commercial and custom-designed carbon materials for the study. The project will provide research opportunities to undergraduate students in the Penn State Commonwealth system. The surface analysis results of this project will be integrated with graduate-level education. Two hypotheses will be studied: (i) Friction of carbon materials depends on the distribution of sp2 and sp3 hybridizations and how they are connected to form the amorphous network, which varies with synthesis method. (ii) The chemical activity of reactive sites exposed at the sliding interface also varies depending on how carbon materials are synthesized. Studying these hypotheses requires the analysis of shear-induced structural transforms and chemical reactions occurring at the frictional interface; but that interface is not readily accessible for in-situ characterization. Alternately, relevant information can be deduced from the ex-situ analysis of the transfer film on the counter-surface formed from different carbon materials. This is because friction is a non-equilibrium process, and the final state of the transfer film will be a function of the initial state and the condition during friction. Various spectroscopic techniques will be employed to analyze the transfer film to identify tribochemical parameters governing friction and wear behaviors of thermally-synthesized carbon materials. 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.