Graphene-reinforced titanium coatings deposited by Cold Gas Spray: Study of microstructure, mechanical and wear properties

Abstract

This study integrates graphene-based nanostructures as reinforcement in a Ti matrix to produce coatings using the Cold Gas Spray (CGS) technique, aiming to enhance mechanical and tribological properties while overcoming some of the limitations of conventional thermal spray methods. The hypothesis holds that incorporating Carbon Nanofibers (GFs) into Ti matrices significantly reinforces these properties compared to pure Ti coatings. The study employed ball milling for the powders obtaining, CGS deposition, and various analytical tests to evaluate the performance of Ti-GFs and pure Ti coatings. Results revealed that Ti-GFs coatings significantly improved in mechanical properties, achieving ultimate tensile strength up to 456 MPa and a strain increase to 2.27%. These improvements are attributed to effective load transfer across the Ti-GFs interfaces, facilitated by strong chemisorption interactions. Additionally, heat treatments at 1000 °C relieved residual stresses and promoted microstructural changes via atomic diffusion, further contributing to the coatings’ strength and ductility. Tribological assessments revealed a 21% reduction in the coefficient of friction for Ti-GFs coatings compared to as-sprayed Ti, though was 2% higher than that of Ti-Bulk. This suggests the potential of graphene as a nanoscale lubricant, though further optimization of GFs dispersion and interface interactions may result in even lower coefficient. These findings highlight the potential of GFs reinforced metal matrix composites applied by CGS for critical applications in sectors such as aerospace and biomedical, which demand materials with high strength and reduced mechanical wear. The study also identifies key areas for future research, including the optimization of graphene dispersion and interface bonding, to fully exploit the benefits of GFs in CGS coatings.