Tribological Properties of Multi-Walled Carbon Nanotube-Cr and Graphene Oxide-Cr Composite Coating

Abstract

Chromium (Cr)-based coatings have been widely used to strengthen the friction reduction and wear resistance on various kinds of surface. Here, the stable aqueous dispersion of oxidized multi-walled carbon nanotube (MWCNT) and graphene oxide nanosheets (GOS) was obtained by ultrasonic oxidation treatment. Then, MWCNT-Cr and GOS-Cr composite coatings were prepared using the direct current electrochemical co-deposition process on 420 stainless steel in the electrolyte with the addition of MWCNT and GOS under different current density and temperature. The morphology, structure, hardness and tribological properties of MWCNT-Cr and GOS-Cr composite coating are comparatively studied using pure Cr coating as a baseline. The friction reduction performance of MWCNT-Cr and GOS-Cr composite coatings was improved at optimum current density and temperature. The anti-wear properties of MWCNT-Cr and GOS-Cr composite coatings were enhanced by uniform embedment of MWCNT and GOS in coatings increasing the hardness and lubricity. This study suggests that the introduction of oxidized MWCNT and GOS with good dispersion could enhance the wear resistance and friction reduction of pure Cr coating due to their excellent dispersion, mechanical, and lubricant properties.