Evaluation of structure and mechanical properties of Ni-P-Al2O3 nanocomposite coatings

In this article, alumina nanoparticles were co-deposited within Ni-P electroless coating on mild steel samples and then isothermal heat treatment was done at 400â., for 1 h. The size distribution of nanoparticles was evaluated by transmission electron microscopy and the concentration of alumina reinforcements in Ni-P matrix was determined using field emission scanning electron microscopy and image analysis software. The phase transformation of coatings was analysed by X-ray diffraction and differential thermal analysis. Also, mechanical properties of coatings were evaluated by microhardness and indentation tests. The results showed that mechanical properties of Ni-P-Al2O3 nanocomposite coatings strongly influences by dispersion and/or precipitation hardening mechanisms.