Tribological Properties of Graphene Oxide Nanosheet Coating Fabricated by Using Electrodynamic Spraying Process

Graphene oxide nanosheet (GONS) coatings were fabricated by using electrodynamic spraying process (ESP) with the aim to utilize the coatings as a solid lubricant. Well-dispersed GONSs in a mixture of EtOH/H₂O solution was deposited on Si (100) substrates. The characteristics of the coatings such as surface roughness and thickness were assessed with respect to the coating process parameters. Tribological properties of the GONS coatings with different thickness were investigated using a pin-on-reciprocating type of a tribotester under various applied loads. Surface morphology and chemical bonding composition of the coatings inside and outside of the wear track were characterized with atomic force microscope and Raman spectroscopy, respectively. The experimental results revealed that with proper ESP conditions, GONS coatings resulted in a low friction coefficient of ~0.1. This outcome was largely attributed to GONS transferred to the counter surface which remained stable throughout the sliding process. Furthermore, GONS coatings showed better surface protection ability and lower frictional property compared with single-layer graphene coatings. The results of this work demonstrate the feasibility of employing ESP to fabricate graphene-based solid lubricants cost effectively.