Abstract
The addition of graphene-based nanomaterials is known to improve the tribology properties of materials by lowering the coefficient of friction and reducing wear. The covering of small areas with thin graphene-based films is routinely carried out; however, a fast and efficient way of covering large areas represents an outstanding challenge. Here we present a method for the deposition of graphene nanoplatelets (GNPs) on stainless steel substrates based on suspension high-velocity oxy fuel thermal spray. GNPs were radially injected into the combustion jet, providing sufficient momentum and moderate heat transfer to facilitate effective bonding with the substrate. Upon unlubricated ball-on-disc wear testing against an alumina counterbody, GNPs undergo gradual exfoliation, covering the substrate and thus lowering the friction coefficient (<0.1). We have reported the formation of a thin layer, composed of GNPs having different amounts of disorder, which protects the underlying substrate from wear. GNP structural ordering is studied throughout deposition and wear tests, showing an increase of inter- and intralayer disorder at the nanoscale, whilst largely preserving the GNP microstructure.
Highlights
The setup we propose here is based on a commercial TopGun stainless steel (SS) (GTV GmbH, Germany) suspension spray gun, where the feedstock is injected radially using a 450 μm diameter injector pointed towards the jet with 15◦ downstream tilt at 10 mm from the gun exit
Higher resolution images obtained with Field Emission Gun (FEG) Scanning Electron Microscopy (SEM) shown in Figure 1b allow better insight into the microstructure of an area of densely packed graphene nanoplatelets (GNPs), revealing a stratification of GNPs stacked in a parallel fashion on top of each other
It is important to assess the structural integrity of GNPs as they are processed into suspension or sprayed
Summary
The choice of this combination of parameters follows an optimization process that aimed at maximizing feedstock penetration in the jet and momentum transfer, while minimizing its permanence in the jet to hinder mechanical and thermal degradation of GNPs. The experimental setup and injection imaging are shown in supplementary material Figure S1.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
