Characterization of novel Ni–Al2O3–SiC nanocomposite coatings synthesized by co-electrodeposition

Abstract

In the present work, Ni–Al2O3, Ni–SiC and novel Ni–Al2O3–SiC metal matrix composite (MMC) coatings were electrodeposited onto pure copper samples using a modified Watt’s nickel electroplating bath containing nano alumina and silicon carbide particles with an average particle size of 50 nm. The composition, crystalline structure and surface morphology of the deposits were characterized by X-ray diffractometry (XRD), energy-dispersive X-ray spectroscopy (EDS) and field emission scanning electron microscopy (FESEM). The results indicated that Ni–Al2O3–SiC hybrid composite films with an acceptable homogeneity and granular structure having 9.2 and 7.7 % vol. Al2O3 and SiC nanoparticles, respectively were developed successfully. The nanoparticles incorporated in the nickel layer effectively increased the micro hardness and wear resistance owing to dispersion and grain-refinement strengthening, changing the nickel matrix morphology as well as the texture and preferred grain growth direction from <100> to the close-packed <111>. The oxidation resistance of the Ni–Al2O3–SiC hybrid composite coatings was measured to be approximately 41 % greater than the unreinforced Ni deposit and almost 30 % better than the Ni–Al2O3 composite coatings.