Feasibility study of GO Coated WC Co-Cr porous powder for improved wear resistance in HVAF coatings

Wear-induced failures in mechanical components remain a critical challenge in industrial applications, necessitating advanced surface engineering solutions. Thermal spraying, particularly high-velocity air fuel (HVAF), is a potential technique for depositing wear-resistant coatings. WC Co-Cr is extensively used due to its exceptional hardness, ductility, and corrosion resistance. Recent studies have explored the incorporation of carbon nanomaterials to enhance the tribological performance of WC Co-Cr coatings, with promising results. Among these, graphene oxide (GO) offers distinct advantages, including cost-effectiveness, processing versatility and layered structure, making it a suitable candidate for wear-resistant coatings. However, achieving uniform distribution and strong interfacial bonding within the matrix remains a challenge. This work presents a feasibility study of a novel approach for incorporating GO into HVAF sprayed WC Co-Cr coatings using a non-commercial porous powder. GO was bonded to the powder surface through a molecular-level mixing process, allowing partial coverage of both the outer surface and inside the pores. The GO-coated powders and the resulting HVAF coatings were characterized using SEM, Raman spectroscopy, TGA, and XPS. GO was found throughout the HVAF coatings, illustrating the advantages of the molecular-level mixing process and the use of porous powder to protect the GO in the spraying process. Tribological tests showed that the GO-reinforced coatings exhibited 10.5% higher hardness, reduced the average friction coefficient in the as-sprayed state from 0.68 to 0.58, and reduced porosity from 13% to 9% compared to coatings with the virgin porous WC Co-Cr powder. The results show that GO can be successfully incorporated into HVAF coatings, leading to improved lubrication and wear resistance compared with the original powder. Nevertheless, prolonged wear testing indicated that GO gradually degrades over time.