Contact-focusing electron flow induced nanosized graphene sheet formation in amorphous carbon films for fast low-friction

摘要

We report a method of contact-focusing electron flow (CFEF) by applying direct current (DC) at the sliding interface between a-C film and steel ball. With the CFEF-method, nanosized graphene sheets were in-situ fabricated at contact area, which induced a fast low-friction behavior. The developments of the friction behavior with different DC values and normal loads were examined for investigating the CFEF-induced low-friction. The friction coefficient dropped one order of magnitude from 0.2 to 0.02 under CFEF-condition, and the run-in period was close to zero. Three key factors for the fast low-friction were found in this study: (1) CFEF at the contact area excited the carbon structural transition from amorphous to graphene sheets. (2) Friction transferred the nanosized graphene sheets to the steel ball. (3) CFEF-friction coupling effect supplied the nanosized graphene sheets into the sliding interface for low-friction. This work shed light on the in-situ fabrication of nanosized graphene sheets at carbon surface and the low-friction application with CFEF-method. (C) 2019 Elsevier Ltd. All rights reserved.