Shape influence on the tribological properties of hexagonal boron nitride nanoplates and nanospheres reinforced epoxy coating

Hexagonal boron nitride was known for its excellent lubricating capacity, however, the shape influence on the tribological properties of hexagonal boron nitride modified epoxy composite coatings was still a challenging requirement. Herein, the boron nitride nanoplates (BNNP) and nanospheres (BNNS) were modified by polydopamine to improve their dispersion in epoxy coatings and the shape influence of two nanoparticles on the tribological property was proved by the micro-morphologies of wear debris. When the mass content of polydopamine-modified BNNS was 0.25 wt%, the friction-reduction and anti-wear effects were the best, and the coefficient of friction and wear rate was reduced by 13.75% and 60.77%, respectively, compared with the pure epoxy coating. The 'ball effect' of BNNS provided rolling friction and the layer-structured debris exhibited good lubricating properties. The enhanced wear mechanism of BNNS provided wider potential application in the mechanical industry, automotive, aerospace, and infrastructure fields.