Impact of Concentrations of AlN Nanoparticles on Properties of Ni-P Coatings Synthesized by Electroless Process

Abstract This study reports the synthesis and characterization of Ni-P-AlN nanocomposite coatings with varying concentrations of aluminium nitride (AlN) nanoparticles. The coatings were deposited on carbon steel substrates using an electroless deposition technique. Structural (XRD, SEM) and compositional analyses (EDX) confirmed the successful co-deposition of AlN nanoparticles into the Ni–P matrix. A comparative analysis of the developed coatings indicates that Ni-P-AlN nanocomposite coatings exhibit their best mechanical and corrosion resistance performance with an optimum composition of AlN nanoparticles at 0.75 g/L. The improvement in microhardness of Ni-P-AlN nanocomposite coatings with increasing concentration of AlN nanoparticles can be attributed to the formation of a compact coating structure, grain refinement, and dispersion hardening effect. Similarly, an enhancement in corrosion protection efficiency of Ni-P-AlN nanocomposite by the gradual increase of AlN nanoparticles may be attributed to the reduction in the active area of the Ni-P matrix and reduced porosity due to the filling of pores by AlN nanoparticles. A decline in mechanical and corrosion-resistant properties beyond the optimal concentration (0.75 g/L) is observed, likely due to excessive agglomeration of AlN nanoparticles caused by their high surface area. These findings demonstrate that Ni-P-AlN nanocomposite coatings are suitable for many industries.