Innovative hybrid coatings: Uniting boron carbide and graphite for enhanced performance in electroless nickel boron coating process

Abstract

In this study, two different powders were harmonized to develop electroless nickel-boron coatings with enhanced hardness and wear resistance. For this purpose, a new hybrid electroless nickel boron composite coating process was developed by using two different characteristic particles which are i) boron carbide and ii) graphite. The surface analysis showed that harmonizing two particles into one single coating bath exhibited good tribological and mechanical properties as compared to conventional single-particle composite and non-composite electroless nickel boron coatings. After the coating process, two different heat treatment procedures were carried out which are i) 250°C-5 hours and ii) 400°C-1 hour. Chemical composition, crystal structures, microhardness, tribological, and corrosion behaviors of the coatings were investigated. The comprehensive results showed the dual effect of different particles which have different characteristics lubricious and abrasive on hardness and tribological properties. The heat treatment process had also a positive effect on the tribological behavior of the hybrid composite coatings. Microhardness values of the hybrid composite coating improved by around 24–37% compared to electroless nickel boron coating alone whereas heat treatment processes led to an increment in hardness of around 50–87%. Besides it was observed that wear rates were 79–93% lower than classic nickel boron coating while heat treatment also decreased the wear rate by 154–165%. The corrosion resistance of the hybrid coating is similar to electroless nickel boron coating however it decreases slightly after the heat treatment process. Overall, the hybrid electroless nickel boron composites were successfully achieved and provide promising features for the coating employed in industrial applications.