Synthesis and characterization of Ni-B/Al2O3 nanocomposite coating by electrodeposition using trimethylamine borane as boron precursor

A novel Ni-B/Al2O3 nanocomposite coating was synthesized through electrodeposition by reinforcing Ni-B matrix with Al2O3 nanoparticles using trimethylamine borane as boron precursor. The effects of trimethylamine borane, Al2O3 nanoparticle, current density, thermal treatment on the properties of the electrodeposited coatings were examined. The morphology, microstructure, corrosion behavior and wear resistance of the Ni-B/Al2O3 coating in their as-deposited states were investigated by SEM, EDX, XRD and electrochemical techniques. It demonstrates that boron content has a beneficial effect on grain refinement and facilitates the formation of the amorphous phase. The hardness and wear resistance of Ni-B coating can be improved by the addition of Al2O3 particles due to the dispersion hardening of the hard Al2O3 particles. Both the boron and Al2O3 nanoparticle content in the deposited Ni-B/Al2O3 coating decreases as the current density increased from 1 to 7 A dm−2. The incorporation of Al2O3 nanoparticles alters the chemical composition, enhances the microhardness, improves the crystallinity of the Ni-B matrix. Owing to the grain refinement of Ni-B matrix, dispersion hardening of the added nanoparticles, as well as the reduction in the active surface area of Ni-B matrix by the presence of inert particles, Ni-B/Al2O3 nanocomposite coating with dense structure shows superior anti-corrosion and wear resistance than Ni/Al2O3 or Ni-B coating.